M. Machuca | Universidad Nacional de La Plata (original) (raw)

Papers by M. Machuca

Transplantation Proceedings, 2016

Background. Intestinal ischemia-reperfusion injury occurs after different surgical treatments, in... more Background. Intestinal ischemia-reperfusion injury occurs after different surgical treatments, including intestinal transplantation. This harmful process may have an effect in remote organs, leading to multiple organ dysfunction syndrome and death. Therefore, to establish strategies to attenuate local and remote damage constitutes a challenge for experimental and clinical surgeons in the intestinal surgical field. Methods. We evaluated the effect of ischemic preconditioning and tacrolimus pretreatment applied alone and in combination against local and remote damage caused by prolonged intestinal ischemia-reperfusion injury in a mouse model of warm ischemia. Results. Ischemic preconditioning applied alone and in combination with tacrolimus decreased histological damage (P < .05), number of apoptotic cells (P < .05), nitrosative stress (P < .01), and serum lactate dehydrogenase activity (P < .05) and lowered uremia (P < .05) compared with untreated post-reperfused intestines. Regarding remote organ damage, combination therapy was the unique condition able to attenuate lung (mainly neutrophil infiltration and hemorrhage), liver (sinusoidal congestion and hepatic vacuolization), and kidney (acute tubular necrosis and hydropic degeneration) histological alterations (P < .05), compared with the untreated group. Conclusions. These results support the application of these strategies in combination to minimize the impact of ischemia-reperfusion injury in the whole organism as a strategy to prevent multiple organ dysfunction syndromes and minimize the clinical impact.

Revista De Medicina Veterinaria, 2000

Journal of Equine Veterinary Science, 2016

Lawsonia intracellularis (Li) is the causative agent of equine proliferative enteropathy (EPE), a... more Lawsonia intracellularis (Li) is the causative agent of equine proliferative enteropathy (EPE), an endemic infection in pigs and an emerging concern in horses. EPE has been reported in North America, Europe, Australia and Brazil, and is more frequent in weaned foals. The antemortem diagnosis of EPE is based on the detection of Liespecific antibodies by serology and the molecular identification of DNA in feces by PCR. The aim of this work is to report an outbreak of EPE in two horse farms in Buenos Aires province. Serology tests were performed both in mares and weanlings (9-12 months) while PCR of faecal samples was performed only in weanlings. The DNA was extracted (ZR MiniPrep Zymo Research, USA) and the PCR was applied according to Jones et al. 1993. The indirect immunofluorescence was carried out according to Knittel et al. 1997. In farm one, sera from 32 mares and two foals with diarrhea and clinical signs were analyzed, while in farm two, sera from 14 mares and 15 foals were processed, where only one had chronic diarrhea and an antibiotic treatment. The results are shown in table 1. Total positive sera were 79% (50/63) and positive PCR in foals 12% (2/17). Besides, at least one animal was positive by PCR in each farm. The high percentage of seropositive animals may indicate previous exposure to Li. The seropositivity of mares implies subclinical infection, a situation of constant exposure or long term persistence of serum antibodies. In a foal with diarrhea and positive PCR may confirm the EPE. However, in a foal with diarrhea and negative PCR, the disease could not ruled out, because a negative result is expected in situations such as a prolonged course or antibiotic therapy. The detection of positive PCR animals without diarrhea, as observed in farm two, can be related to a subclinical infection, a common condition seen in swine. In conclusion, to our knowledge, this is the first description clinical and subclinical case of EPE with confirmed diagnosis by serology and fecal PCR in horses in Argentina. The EPE must be considered among the possible diagnoses in cases of enteritis in foals. Use of these tests may aid in detection of the disease allowing for early and specific treatment to improve the prognosis of affected horses. *Acute diarrhea; 1 Without diarrhea; 2 Chronic diarrhea + antibiotictherapy.

Journal of Veterinary Medicine Series A, 2002

Peripheral neuroblastoma (PNB) is a rare neoplasia derived from neuroepithelial cells. PNB typica... more Peripheral neuroblastoma (PNB) is a rare neoplasia derived from neuroepithelial cells. PNB typically presents as a greyish mass, composed of round cells with features of neuronal differentiation. Necropsy, performed on a 1-day-old piglet, revealed a mass craniodorsally located in the abdominal cavity. Histologically, the predominant population consisted of small round to ovoid cells with scanty cytoplasm and dark round nuclei, besides, there were larger neurone-like cells. Neuronespecific enolase and S-100 protein were immunohistochemically detected, while glial fibrillary acidic protein was negative. Histological and immunohistochemical findings substantiated the diagnosis of a grade II peripheral neuroblastoma. This seems to be the first description of a PNB in a newborn piglet.

In June–July 2009, an outbreak of pandemic (H1N1) 2009 infection occurred on a pig farm in Argent... more In June–July 2009, an outbreak of pandemic (H1N1) 2009 infection occurred on a pig farm in Argentina. Molecular analysis indicated that the virus was genetically related to the pandemic (H1N1) 2009 infl uenza virus strain. The outbreak presumably resulted from direct human-to-pig transmission. Swine influenza viruses (SIVs) occur worldwide; they usually cause asymptomatic infection but occasionally cause outbreaks of varying intensity (1,2). In North America, the landscape of swine influenza has changed substantially since the late 1990s, when human (H3N2) viruses were first isolated from swine and triple reassortant viruses carrying influenza genes (TRIG) of avian, swine, and human origin and showing great reassortment flexibility emerged concurrently. TRIGs of influenza subtypes H3N2, H1N1, H3N1, and H1N2 appear to be circulating in swine in North America. Coincidentally, 1 of these TRIG viruses led to emergence of the pandemic (H1N1) 2009 virus

Veterinary parasitology, Jan 19, 2010

Toxoplasma gondii infection is frequently asymptomatic; however, it can be severe or even fatal t... more Toxoplasma gondii infection is frequently asymptomatic; however, it can be severe or even fatal to some hosts. In this study, diagnosis of disseminated toxoplasmosis in one red kangaroo (Macropus rufus) and one great grey kangaroo (Macropus giganteus) from the La Plata Zoo, Argentina and the isolation and molecular characterization of T. gondii are reported. Both male kangaroos showed depression and sudden death. Toxoplasma gondii infection was diagnosed by fresh examination, histopathology, immunohistochemistry, PCR and bioassay in mice. During fresh examination many protozoan cysts were observed in diaphragm, heart and hind limb muscles of M. rufus. Cysts were also observed in samples from M. giganteus, although in lower number. Cysts from both kangaroos stained strongly with T. gondii anti-serum by immunohistochemistry. The M. rufus showed more considerable histopathological lesions like non-suppurative meningoencephalitis, myositis and myocarditis. All mice inoculated with tissu...

Influenza and Other Respiratory Viruses, 2013

Background Influenza A viruses (IAV) are important pathogens responsible for economic losses in t... more Background Influenza A viruses (IAV) are important pathogens responsible for economic losses in the swine industry and represent a threat to public health. In Argentina, clinical, pathological, and virological findings suggest that IAV infection is widespread among pig farms. In addition, several subtypes of IAV, such as pH1N1, H3N2, d1H1N1, and d2H1N2, have been reported. Objectives To evaluate the infection patterns of influenza virus in nine pig farms in Argentina. Methods Clinical, serological, pathological, and virological crosssectional studies were conducted. Results Clinical and pathological results were characteristic of endemic influenza infection in eight of the nine farms studied. By rRT-PCR, six of the nine farms were positive to influenza. Five IAV were obtained. Genome analysis determined that four of the isolations were pH1N1 and that the remaining one was a reassortant human origin H3N2 virus containing pandemic internal genes. Serological results showed that all farms were positive to influenza A antibodies. Moreover, the hemagglutination inhibition test showed that infection with viruses containing HA′s from different subtypes (pH1, d1H1, d2H1, and H3) is present among the farms studied and that coinfections with two or more subtypes were present in 80.5% of positive pigs. Conclusions Because vaccines against IAV are not licensed in Argentina, these results reflect the situation of IAV infection in nonvaccinated herds. This study provides more information about the circulation and characteristics of IAV in a poorly surveyed region. This study provides more data that will be used to evaluate the tools necessary to control this disease.

Foodborne Pathogens and Disease, 2009

The aim of this surveillance was to study both Salmonella spp. shedding patterns and the time cou... more The aim of this surveillance was to study both Salmonella spp. shedding patterns and the time course of serological response in farrow-to-finish reared pigs from a subclinically infected farm. Antimicrobial resistance profile, molecular subtyping, and the relationship among the isolates were determined by pulsed-field gel electrophoresis (PFGE). A farrow-to-finish farm of 6000 sows, with a history of Salmonella Typhimurium septicemia, was selected. A longitudinal bacteriological and serological study was conducted in 25 sows before farrowing (M=S1) and in 50 offspring at 21 (M=S2), 35 (M=S3), 65 (M=S4), 86 (M=S5), 128 (M=S6), and 165 (M=S7) days of age. Serum antibodies were tested using Herdcheck Ò Swine Salmonella antibody test kit (Idexx Laboratories, ME). Bacteria were isolated from pooled fecal samples. Suspected isolates were confirmed by conventional biochemical assays, and those identified as Salmonella spp. were serotyped. A variation between seropositive percentages and positive fecal samples was observed. Serologically positive pigs decreased from S1 to S4, and subsequently increased from S4 to S7. The percentages of fecal positive culture increased from M1 to M3, and then declined in M4, increased in M5, and were negative in M6 and M7. In the study three serovars, Salmonella 3,10:e,h:-, Salmonella Muenster, and Salmonella Bovismorbificans, were identified with low pathogenicity for swine. Three multidrug resistance strains (one belonged to Salmonella 3,10:e,h:-and two belonged to Salmonella Muenster) were found. PFGE results showed three different but closely related patterns among the 13 isolates of Salmonella Bovismorbificans, and two patterns for the three Salmonella Muenster and Salmonella 3,10:e,h:-isolates. This longitudinal study established critical points of Salmonella spp. infection in the farm and the production stages, where appropriate control measures must be taken. PFGE showed clonal relationships in each serovar. Antibiotic resistance profiles should be periodically included due to public health concerns.

Emerging Infectious Diseases, 2010

Brazilian journal of …, 2009

Clostridium difficile is a Gram-positive opportunistic anaerobic bacterium found in the soil, wat... more Clostridium difficile is a Gram-positive opportunistic anaerobic bacterium found in the soil, water as well as the digestive tract of several species of mammals. Currently in high-health herds and not related with antibiotic treatment, C. difficile has been emerged in association with neonatal catarrhal, fibrinous or purulent colitis in 2 to 7 day-old piglets. Mesocolon edema and colitis with a "volcano" lesion are pathological key marks of C. difficile infection. In farm 1, the prevalence of neonatal piglet mesocolon edema and colitis was evaluated in an extensive study of postmortem preweaning mortality. Lectinhistochemistry pattern of normal colon and colon with edema and colitis were analyzed in order to provide more accurate information related with pathogenesis of C.difficile infection. In farm 2, a clinical description of an outbreak of neonatal colitis in piglets due to C. difficile infection was reported. A total 820 piglets were post-mortem examined, from them, 8 cases were classified as suspected of C. difficile infection (0.1%). Age of affected piglets varied between 3 to 14 days. In all of them, the key mark was the severe mesocolon edema and 2 cases were characterized by focal necrosis and loss of epithelial cells associated with a focal infiltration of neutrophils and macrophages in the lamina propria and lumen like erupted volcano. Lectins SBA and DBA that has affinity to α Gal epitope were negative in normal samples but reacted strongly positive at the glycocalix of the villi enterocytes of the affected samples indicating a change in the carbohydrates pattern of the cells surfaces that might favor the binding of C. difficile toxin A (TcdA). In farm 2, from 11 examined piglets, 6 of them (54%) showed different degree of mesocolon edema and in only 2 of them; volcano lesions were the main histopathological findings. Rectal swab from 8 diarrheic and 5 postmortem examined piglets were surveyed for eltA estI estII and stx 2e virulence gens of E. coli and all samples were negative. Clostridium difficile toxins A and B were identified only in the sample with severe gross and microscopic changes. Isolation of C. difficile was unsuccessfully. Infection of C. difficile is present in Argentinean pig farms. Diagnosis of subclinical infection might be negligent if post-mortem studies of preweaning mortality at weekly intervals are not performed. However, when clinical disease appeared, mortality might be high as it was reported in the farm 2. Comparative lectinhistochemistry studies from field cases added further information of the carbohydrates present on glycocalix of villi enterocytes related with toxin receptors.

Archivos de medicina veterinaria, 1999

Los objetivos de este trabajo fueron caracterizar los lechones mortinatos provenientes de tres gr... more Los objetivos de este trabajo fueron caracterizar los lechones mortinatos provenientes de tres granjas de cria intensiva en confinamiento de ]a provincia de Buenos Aires, Argentina, sobre ]a base de los hallazgos anatomopatologicos macroscopicos y determinar, mediante estudios inmunoserologicos del liquido pleural, la presencia de algunos agentes infecciosos que inciden en su presentacion. Se realizo ]a necropsia de 1.024 mortinatos, los que se clasificaron en intraparto, anteparto momificados y anteparto no momificados, Se tomaron muestras de liquido pleural, de las cuales 200 fueron procesadas para la determinacion de anticuerpos contra parvovirus porcino, virus de la enfermedad de Aujeszky, Leptospira interrogans (4 serogrupos) y Brucella suis, Para Toxoplasma gondii fueron procesadas 738 muestras. Los porcentajes de mortinatos totales en las granjas A, B Y C fueron 4, 1, 3.4 Y 10.8%, respectivamente, En las granjas A y C e] mayor porcentaje fue para los intraparto (61.8 y 92.2%), mientras que en ]a B fue para los anteparto momificados (54, 8%). En A y C, el alto porcentaje de mortinatos intraparto se asocio con la presencia de anticuerpos contra L. Interrogans serogrupo Icterohemorrhagiae, mientras que en la B el alto porcentaje de momias se relaciono con la presencia de anticuerpos contra parvovirus porcino. En las 3 granjas se observo positividad al T. Gondii, en particular en la B, siendo este hallazgo coincidente con la presencia de gatos. La determinacion de anticuerpos contra virus de la enfermedad de Aujeszky y B. Suis fue negativa en las 3 granjas. La caracterizacion de los mortinatos asociada a la determinacion de anticuerpos en liquido pleural constituyo un metodo simple y efectivo, resultando de utilidad como herramienta complementaria en la determinacion del perfil sero]ogico de exposicion a patogenos que producen trastornos reproductivos.

Archivos de medicina veterinaria, 1999

A new viral agent was found associated with the endoplasmic reticulum of epithelial cells of the ... more A new viral agent was found associated with the endoplasmic reticulum of epithelial cells of the Paci®c white shrimp Litopenaeus vannamei (Boone) sampled during mass mortalities. A 40% mortality rate affected nursery and grow-out ponds during the ®rst 50±60 days of culture, and peak mortality in ponds occurred when shrimp reached 2±4 g. Histopathological changes of affected shrimp showed different grades of necrosis in epithelial cells and, in some cases, other tissues were affected. Transmission electron microscopy (TEM) of columnar cells of the cuticular epithelium showed the accumulation of viral particles, either dispersed in the cytoplasm or in a string-like or paracrystalline array. These arrays of virions were within membrane-bound vesicles formed from the endoplasmic reticulum (ER), in orderly arrays on the outer nuclear membrane or along the ER. The virus particles had apparently proliferated in the ER. The virions had an opaque area with an approximate diameter of 20 nm and an electron-lucent surface layer. The approximate diameter of the nonenveloped virions was 25 nm. The cytological changes observed are similar to those associated with the Picornaviridae and Nodaviridae families. The histopathology and ultrastructure of a new disease in L. vannamei is associated with the presence of a putative new virus. Until further isolation and characterization is performed, it is recommended to refer to the agent as Litopenaeus vannamei viral-like particles (LvVLPs).

Machuca, M.; Cappuccio, J.; Piñeyro. P.;Quiroga, A. y Vigo, G.*. 2006. Vº Congreso de Produccion ... more Machuca, M.; Cappuccio, J.; Piñeyro. P.;Quiroga, A. y Vigo, G.*. 2006. Vº Congreso de Produccion Porcina del Mercosur, Río Cuarto. Facultad de Ciencias Veterinarias, UNLP, La Plata. www.produccion-animal.com.ar Volver a: Vº Congreso

Veterinary Parasitology, 1999

Fetal fluids of 738 stillborn piglets from three swine farms in Argentina were examined for antib... more Fetal fluids of 738 stillborn piglets from three swine farms in Argentina were examined for antibodies to Toxoplasma gondii. Antibodies were detected in 15 samples at a 1:20 dilution in the indirect fluorescent antibody test and 10 samples were positive in the modified agglutination test (MAT) at a dilution of 1:25; four of these samples had a MAT titer of &gt; or = 1:100. This survey indicates a low rate of congenital T. gondii infection in stillborn pigs in Argentina.

Veterinary Parasitology, 2005

Generalized neosporosis was diagnosed in a 2-month-old boxer puppy. The dog had a history of prog... more Generalized neosporosis was diagnosed in a 2-month-old boxer puppy. The dog had a history of progressive paralysis and muscle atrophy, followed by cervical weakness, stiff jaws and dysphagia. The dog had a 1:12,800 antibody titer for Neospora caninum and was negative for antibodies to Toxoplasma gondii by the indirect fluorescent antibody test (IFAT). After euthanasia a complete necropsy was carried out. The puppy had a megaesophagus. Microscopically, tachyzoites and tissue cysts were observed in histologic brain sections. Severe myositis was observed in esophagus and striated muscle sections and several groups of tachyzoites were associated with these lesions. Immunohistochemically, parasites in the brain and striated muscle reacted to anti-N. caninum antiserum. Western blot analysis allowed the identification of three major and four minor antigens of N. caninum tachyzoites corresponding to 30, 37, 29, 43, 47 and 67-kDa bands, respectively. Cerebral homogenate of the dog was inoculated into four Mongolian gerbils (Meriones unguiculatus). Forty-nine days after inoculation, all the gerbils had positive IFAT titers to N. caninum (1:200, 1:400, 1:100 and 1:400). Genomic DNA was isolated from the brain, lung and striated muscle from the puppy and from the brain of one of the inoculated gerbils. The N. caninum specific primer pair Np 6/21 produced 328 bp amplicons on electrophoretic gels. This is the first confirmed clinical case of generalized canine neosporosis in Argentina. #

Transplantation Proceedings, 2012

Among the abdominal organs, the intestine is probably the most sensitive to ischemia reperfusion ... more Among the abdominal organs, the intestine is probably the most sensitive to ischemia reperfusion injury (IRI), a phenomenon that occurs in many intestinal disorders. Few studies have reported in detail the impact of intestinal ischemia time in mice. We evaluated the effect of various warm intestinal ischemia times in an intestinal IRI model in mice. Adult male Balb/c mice were divided into 4 groups that differed in intestinal ischemia time: G1, 30; minutes; G2, 35 minutes; G3, 40 minutes; and G4, 45 minutes. Histological evaluation showed average Park scores as follows: G1 0.6 Ϯ 0.55; G2 1.8 Ϯ 0.45; G3 4.8 Ϯ 2.25; and G4 5 Ϯ 1.79. All animals from G1 survived 30 hours. G2 animals showed intermediate behavior with all succumbing between 18 and 30 hours postprocedure. G3 and G4 displayed similar survival results with animals succumbing before 6 hours after intestinal reperfusion. These data showed that Park index scores of 3 or higher were related to early death. We concluded that the 5 minutes between 35 and 40 minutes is the critical limit, after which all mice die after reperfusion. This result may represent a valuable tool for future research in mice. Address reprint requests to Pablo Luis Stringa, Instituto de Transplante Multiorgánico Fundación Favaloro, Avenida Belgrano 1782 (7 no piso), CABA (1093),

Transplantation Proceedings, 2013

The intestine is highly sensitive to ischemia-reperfusion injury (IRI), a phenomenon occurring in... more The intestine is highly sensitive to ischemia-reperfusion injury (IRI), a phenomenon occurring in different intestinal diseases. Several strategies to mitigate IRI are in experimental stages; unfortunately, no consensus has been reached about the most appropriate one. We report a protocol to study ischemic preconditioning (IPC) evaluation in mice and to combine IPC and tacrolimus (TAC) pretreatment in a warm ischemia model. Mice were divided into treated (IPC, TAC, and IPC þ TAC) and untreated groups before intestinal ischemia. IPC, TAC, and IPC þ TAC groups were able to decrease postreperfusion nitrites levels (P < .05). IPC-containing groups had a major beneficial effect by preserving the integrity of the intestinal histology (P < .05) and improving animal survival (P < .002) compared with TAC alone or the untreated group. The IPC þ TAC group was the only one that showed significant improvement in lung histological analysis (P < .05). The TAC and IPC þ TAC groups down-regulated intestinal expression of interleukin (II)-6 and IL1b more than 10-fold compared with the control group. Although IPC and TAC alone reduced intestinal IRI, the used of a combined therapy produced the most significant results in all the local and distant evaluated parameters.

Transplantation Proceedings, 2016

Background. Intestinal ischemia-reperfusion injury occurs after different surgical treatments, in... more Background. Intestinal ischemia-reperfusion injury occurs after different surgical treatments, including intestinal transplantation. This harmful process may have an effect in remote organs, leading to multiple organ dysfunction syndrome and death. Therefore, to establish strategies to attenuate local and remote damage constitutes a challenge for experimental and clinical surgeons in the intestinal surgical field. Methods. We evaluated the effect of ischemic preconditioning and tacrolimus pretreatment applied alone and in combination against local and remote damage caused by prolonged intestinal ischemia-reperfusion injury in a mouse model of warm ischemia. Results. Ischemic preconditioning applied alone and in combination with tacrolimus decreased histological damage (P < .05), number of apoptotic cells (P < .05), nitrosative stress (P < .01), and serum lactate dehydrogenase activity (P < .05) and lowered uremia (P < .05) compared with untreated post-reperfused intestines. Regarding remote organ damage, combination therapy was the unique condition able to attenuate lung (mainly neutrophil infiltration and hemorrhage), liver (sinusoidal congestion and hepatic vacuolization), and kidney (acute tubular necrosis and hydropic degeneration) histological alterations (P < .05), compared with the untreated group. Conclusions. These results support the application of these strategies in combination to minimize the impact of ischemia-reperfusion injury in the whole organism as a strategy to prevent multiple organ dysfunction syndromes and minimize the clinical impact.

Revista De Medicina Veterinaria, 2000

Journal of Equine Veterinary Science, 2016

Lawsonia intracellularis (Li) is the causative agent of equine proliferative enteropathy (EPE), a... more Lawsonia intracellularis (Li) is the causative agent of equine proliferative enteropathy (EPE), an endemic infection in pigs and an emerging concern in horses. EPE has been reported in North America, Europe, Australia and Brazil, and is more frequent in weaned foals. The antemortem diagnosis of EPE is based on the detection of Liespecific antibodies by serology and the molecular identification of DNA in feces by PCR. The aim of this work is to report an outbreak of EPE in two horse farms in Buenos Aires province. Serology tests were performed both in mares and weanlings (9-12 months) while PCR of faecal samples was performed only in weanlings. The DNA was extracted (ZR MiniPrep Zymo Research, USA) and the PCR was applied according to Jones et al. 1993. The indirect immunofluorescence was carried out according to Knittel et al. 1997. In farm one, sera from 32 mares and two foals with diarrhea and clinical signs were analyzed, while in farm two, sera from 14 mares and 15 foals were processed, where only one had chronic diarrhea and an antibiotic treatment. The results are shown in table 1. Total positive sera were 79% (50/63) and positive PCR in foals 12% (2/17). Besides, at least one animal was positive by PCR in each farm. The high percentage of seropositive animals may indicate previous exposure to Li. The seropositivity of mares implies subclinical infection, a situation of constant exposure or long term persistence of serum antibodies. In a foal with diarrhea and positive PCR may confirm the EPE. However, in a foal with diarrhea and negative PCR, the disease could not ruled out, because a negative result is expected in situations such as a prolonged course or antibiotic therapy. The detection of positive PCR animals without diarrhea, as observed in farm two, can be related to a subclinical infection, a common condition seen in swine. In conclusion, to our knowledge, this is the first description clinical and subclinical case of EPE with confirmed diagnosis by serology and fecal PCR in horses in Argentina. The EPE must be considered among the possible diagnoses in cases of enteritis in foals. Use of these tests may aid in detection of the disease allowing for early and specific treatment to improve the prognosis of affected horses. *Acute diarrhea; 1 Without diarrhea; 2 Chronic diarrhea + antibiotictherapy.

Journal of Veterinary Medicine Series A, 2002

Peripheral neuroblastoma (PNB) is a rare neoplasia derived from neuroepithelial cells. PNB typica... more Peripheral neuroblastoma (PNB) is a rare neoplasia derived from neuroepithelial cells. PNB typically presents as a greyish mass, composed of round cells with features of neuronal differentiation. Necropsy, performed on a 1-day-old piglet, revealed a mass craniodorsally located in the abdominal cavity. Histologically, the predominant population consisted of small round to ovoid cells with scanty cytoplasm and dark round nuclei, besides, there were larger neurone-like cells. Neuronespecific enolase and S-100 protein were immunohistochemically detected, while glial fibrillary acidic protein was negative. Histological and immunohistochemical findings substantiated the diagnosis of a grade II peripheral neuroblastoma. This seems to be the first description of a PNB in a newborn piglet.

In June–July 2009, an outbreak of pandemic (H1N1) 2009 infection occurred on a pig farm in Argent... more In June–July 2009, an outbreak of pandemic (H1N1) 2009 infection occurred on a pig farm in Argentina. Molecular analysis indicated that the virus was genetically related to the pandemic (H1N1) 2009 infl uenza virus strain. The outbreak presumably resulted from direct human-to-pig transmission. Swine influenza viruses (SIVs) occur worldwide; they usually cause asymptomatic infection but occasionally cause outbreaks of varying intensity (1,2). In North America, the landscape of swine influenza has changed substantially since the late 1990s, when human (H3N2) viruses were first isolated from swine and triple reassortant viruses carrying influenza genes (TRIG) of avian, swine, and human origin and showing great reassortment flexibility emerged concurrently. TRIGs of influenza subtypes H3N2, H1N1, H3N1, and H1N2 appear to be circulating in swine in North America. Coincidentally, 1 of these TRIG viruses led to emergence of the pandemic (H1N1) 2009 virus

Veterinary parasitology, Jan 19, 2010

Toxoplasma gondii infection is frequently asymptomatic; however, it can be severe or even fatal t... more Toxoplasma gondii infection is frequently asymptomatic; however, it can be severe or even fatal to some hosts. In this study, diagnosis of disseminated toxoplasmosis in one red kangaroo (Macropus rufus) and one great grey kangaroo (Macropus giganteus) from the La Plata Zoo, Argentina and the isolation and molecular characterization of T. gondii are reported. Both male kangaroos showed depression and sudden death. Toxoplasma gondii infection was diagnosed by fresh examination, histopathology, immunohistochemistry, PCR and bioassay in mice. During fresh examination many protozoan cysts were observed in diaphragm, heart and hind limb muscles of M. rufus. Cysts were also observed in samples from M. giganteus, although in lower number. Cysts from both kangaroos stained strongly with T. gondii anti-serum by immunohistochemistry. The M. rufus showed more considerable histopathological lesions like non-suppurative meningoencephalitis, myositis and myocarditis. All mice inoculated with tissu...

Influenza and Other Respiratory Viruses, 2013

Background Influenza A viruses (IAV) are important pathogens responsible for economic losses in t... more Background Influenza A viruses (IAV) are important pathogens responsible for economic losses in the swine industry and represent a threat to public health. In Argentina, clinical, pathological, and virological findings suggest that IAV infection is widespread among pig farms. In addition, several subtypes of IAV, such as pH1N1, H3N2, d1H1N1, and d2H1N2, have been reported. Objectives To evaluate the infection patterns of influenza virus in nine pig farms in Argentina. Methods Clinical, serological, pathological, and virological crosssectional studies were conducted. Results Clinical and pathological results were characteristic of endemic influenza infection in eight of the nine farms studied. By rRT-PCR, six of the nine farms were positive to influenza. Five IAV were obtained. Genome analysis determined that four of the isolations were pH1N1 and that the remaining one was a reassortant human origin H3N2 virus containing pandemic internal genes. Serological results showed that all farms were positive to influenza A antibodies. Moreover, the hemagglutination inhibition test showed that infection with viruses containing HA′s from different subtypes (pH1, d1H1, d2H1, and H3) is present among the farms studied and that coinfections with two or more subtypes were present in 80.5% of positive pigs. Conclusions Because vaccines against IAV are not licensed in Argentina, these results reflect the situation of IAV infection in nonvaccinated herds. This study provides more information about the circulation and characteristics of IAV in a poorly surveyed region. This study provides more data that will be used to evaluate the tools necessary to control this disease.

Foodborne Pathogens and Disease, 2009

The aim of this surveillance was to study both Salmonella spp. shedding patterns and the time cou... more The aim of this surveillance was to study both Salmonella spp. shedding patterns and the time course of serological response in farrow-to-finish reared pigs from a subclinically infected farm. Antimicrobial resistance profile, molecular subtyping, and the relationship among the isolates were determined by pulsed-field gel electrophoresis (PFGE). A farrow-to-finish farm of 6000 sows, with a history of Salmonella Typhimurium septicemia, was selected. A longitudinal bacteriological and serological study was conducted in 25 sows before farrowing (M=S1) and in 50 offspring at 21 (M=S2), 35 (M=S3), 65 (M=S4), 86 (M=S5), 128 (M=S6), and 165 (M=S7) days of age. Serum antibodies were tested using Herdcheck Ò Swine Salmonella antibody test kit (Idexx Laboratories, ME). Bacteria were isolated from pooled fecal samples. Suspected isolates were confirmed by conventional biochemical assays, and those identified as Salmonella spp. were serotyped. A variation between seropositive percentages and positive fecal samples was observed. Serologically positive pigs decreased from S1 to S4, and subsequently increased from S4 to S7. The percentages of fecal positive culture increased from M1 to M3, and then declined in M4, increased in M5, and were negative in M6 and M7. In the study three serovars, Salmonella 3,10:e,h:-, Salmonella Muenster, and Salmonella Bovismorbificans, were identified with low pathogenicity for swine. Three multidrug resistance strains (one belonged to Salmonella 3,10:e,h:-and two belonged to Salmonella Muenster) were found. PFGE results showed three different but closely related patterns among the 13 isolates of Salmonella Bovismorbificans, and two patterns for the three Salmonella Muenster and Salmonella 3,10:e,h:-isolates. This longitudinal study established critical points of Salmonella spp. infection in the farm and the production stages, where appropriate control measures must be taken. PFGE showed clonal relationships in each serovar. Antibiotic resistance profiles should be periodically included due to public health concerns.

Emerging Infectious Diseases, 2010

Brazilian journal of …, 2009

Clostridium difficile is a Gram-positive opportunistic anaerobic bacterium found in the soil, wat... more Clostridium difficile is a Gram-positive opportunistic anaerobic bacterium found in the soil, water as well as the digestive tract of several species of mammals. Currently in high-health herds and not related with antibiotic treatment, C. difficile has been emerged in association with neonatal catarrhal, fibrinous or purulent colitis in 2 to 7 day-old piglets. Mesocolon edema and colitis with a "volcano" lesion are pathological key marks of C. difficile infection. In farm 1, the prevalence of neonatal piglet mesocolon edema and colitis was evaluated in an extensive study of postmortem preweaning mortality. Lectinhistochemistry pattern of normal colon and colon with edema and colitis were analyzed in order to provide more accurate information related with pathogenesis of C.difficile infection. In farm 2, a clinical description of an outbreak of neonatal colitis in piglets due to C. difficile infection was reported. A total 820 piglets were post-mortem examined, from them, 8 cases were classified as suspected of C. difficile infection (0.1%). Age of affected piglets varied between 3 to 14 days. In all of them, the key mark was the severe mesocolon edema and 2 cases were characterized by focal necrosis and loss of epithelial cells associated with a focal infiltration of neutrophils and macrophages in the lamina propria and lumen like erupted volcano. Lectins SBA and DBA that has affinity to α Gal epitope were negative in normal samples but reacted strongly positive at the glycocalix of the villi enterocytes of the affected samples indicating a change in the carbohydrates pattern of the cells surfaces that might favor the binding of C. difficile toxin A (TcdA). In farm 2, from 11 examined piglets, 6 of them (54%) showed different degree of mesocolon edema and in only 2 of them; volcano lesions were the main histopathological findings. Rectal swab from 8 diarrheic and 5 postmortem examined piglets were surveyed for eltA estI estII and stx 2e virulence gens of E. coli and all samples were negative. Clostridium difficile toxins A and B were identified only in the sample with severe gross and microscopic changes. Isolation of C. difficile was unsuccessfully. Infection of C. difficile is present in Argentinean pig farms. Diagnosis of subclinical infection might be negligent if post-mortem studies of preweaning mortality at weekly intervals are not performed. However, when clinical disease appeared, mortality might be high as it was reported in the farm 2. Comparative lectinhistochemistry studies from field cases added further information of the carbohydrates present on glycocalix of villi enterocytes related with toxin receptors.

Archivos de medicina veterinaria, 1999

Los objetivos de este trabajo fueron caracterizar los lechones mortinatos provenientes de tres gr... more Los objetivos de este trabajo fueron caracterizar los lechones mortinatos provenientes de tres granjas de cria intensiva en confinamiento de ]a provincia de Buenos Aires, Argentina, sobre ]a base de los hallazgos anatomopatologicos macroscopicos y determinar, mediante estudios inmunoserologicos del liquido pleural, la presencia de algunos agentes infecciosos que inciden en su presentacion. Se realizo ]a necropsia de 1.024 mortinatos, los que se clasificaron en intraparto, anteparto momificados y anteparto no momificados, Se tomaron muestras de liquido pleural, de las cuales 200 fueron procesadas para la determinacion de anticuerpos contra parvovirus porcino, virus de la enfermedad de Aujeszky, Leptospira interrogans (4 serogrupos) y Brucella suis, Para Toxoplasma gondii fueron procesadas 738 muestras. Los porcentajes de mortinatos totales en las granjas A, B Y C fueron 4, 1, 3.4 Y 10.8%, respectivamente, En las granjas A y C e] mayor porcentaje fue para los intraparto (61.8 y 92.2%), mientras que en ]a B fue para los anteparto momificados (54, 8%). En A y C, el alto porcentaje de mortinatos intraparto se asocio con la presencia de anticuerpos contra L. Interrogans serogrupo Icterohemorrhagiae, mientras que en la B el alto porcentaje de momias se relaciono con la presencia de anticuerpos contra parvovirus porcino. En las 3 granjas se observo positividad al T. Gondii, en particular en la B, siendo este hallazgo coincidente con la presencia de gatos. La determinacion de anticuerpos contra virus de la enfermedad de Aujeszky y B. Suis fue negativa en las 3 granjas. La caracterizacion de los mortinatos asociada a la determinacion de anticuerpos en liquido pleural constituyo un metodo simple y efectivo, resultando de utilidad como herramienta complementaria en la determinacion del perfil sero]ogico de exposicion a patogenos que producen trastornos reproductivos.

Archivos de medicina veterinaria, 1999

A new viral agent was found associated with the endoplasmic reticulum of epithelial cells of the ... more A new viral agent was found associated with the endoplasmic reticulum of epithelial cells of the Paci®c white shrimp Litopenaeus vannamei (Boone) sampled during mass mortalities. A 40% mortality rate affected nursery and grow-out ponds during the ®rst 50±60 days of culture, and peak mortality in ponds occurred when shrimp reached 2±4 g. Histopathological changes of affected shrimp showed different grades of necrosis in epithelial cells and, in some cases, other tissues were affected. Transmission electron microscopy (TEM) of columnar cells of the cuticular epithelium showed the accumulation of viral particles, either dispersed in the cytoplasm or in a string-like or paracrystalline array. These arrays of virions were within membrane-bound vesicles formed from the endoplasmic reticulum (ER), in orderly arrays on the outer nuclear membrane or along the ER. The virus particles had apparently proliferated in the ER. The virions had an opaque area with an approximate diameter of 20 nm and an electron-lucent surface layer. The approximate diameter of the nonenveloped virions was 25 nm. The cytological changes observed are similar to those associated with the Picornaviridae and Nodaviridae families. The histopathology and ultrastructure of a new disease in L. vannamei is associated with the presence of a putative new virus. Until further isolation and characterization is performed, it is recommended to refer to the agent as Litopenaeus vannamei viral-like particles (LvVLPs).

Machuca, M.; Cappuccio, J.; Piñeyro. P.;Quiroga, A. y Vigo, G.*. 2006. Vº Congreso de Produccion ... more Machuca, M.; Cappuccio, J.; Piñeyro. P.;Quiroga, A. y Vigo, G.*. 2006. Vº Congreso de Produccion Porcina del Mercosur, Río Cuarto. Facultad de Ciencias Veterinarias, UNLP, La Plata. www.produccion-animal.com.ar Volver a: Vº Congreso

Veterinary Parasitology, 1999

Fetal fluids of 738 stillborn piglets from three swine farms in Argentina were examined for antib... more Fetal fluids of 738 stillborn piglets from three swine farms in Argentina were examined for antibodies to Toxoplasma gondii. Antibodies were detected in 15 samples at a 1:20 dilution in the indirect fluorescent antibody test and 10 samples were positive in the modified agglutination test (MAT) at a dilution of 1:25; four of these samples had a MAT titer of &gt; or = 1:100. This survey indicates a low rate of congenital T. gondii infection in stillborn pigs in Argentina.

Veterinary Parasitology, 2005

Generalized neosporosis was diagnosed in a 2-month-old boxer puppy. The dog had a history of prog... more Generalized neosporosis was diagnosed in a 2-month-old boxer puppy. The dog had a history of progressive paralysis and muscle atrophy, followed by cervical weakness, stiff jaws and dysphagia. The dog had a 1:12,800 antibody titer for Neospora caninum and was negative for antibodies to Toxoplasma gondii by the indirect fluorescent antibody test (IFAT). After euthanasia a complete necropsy was carried out. The puppy had a megaesophagus. Microscopically, tachyzoites and tissue cysts were observed in histologic brain sections. Severe myositis was observed in esophagus and striated muscle sections and several groups of tachyzoites were associated with these lesions. Immunohistochemically, parasites in the brain and striated muscle reacted to anti-N. caninum antiserum. Western blot analysis allowed the identification of three major and four minor antigens of N. caninum tachyzoites corresponding to 30, 37, 29, 43, 47 and 67-kDa bands, respectively. Cerebral homogenate of the dog was inoculated into four Mongolian gerbils (Meriones unguiculatus). Forty-nine days after inoculation, all the gerbils had positive IFAT titers to N. caninum (1:200, 1:400, 1:100 and 1:400). Genomic DNA was isolated from the brain, lung and striated muscle from the puppy and from the brain of one of the inoculated gerbils. The N. caninum specific primer pair Np 6/21 produced 328 bp amplicons on electrophoretic gels. This is the first confirmed clinical case of generalized canine neosporosis in Argentina. #

Transplantation Proceedings, 2012

Among the abdominal organs, the intestine is probably the most sensitive to ischemia reperfusion ... more Among the abdominal organs, the intestine is probably the most sensitive to ischemia reperfusion injury (IRI), a phenomenon that occurs in many intestinal disorders. Few studies have reported in detail the impact of intestinal ischemia time in mice. We evaluated the effect of various warm intestinal ischemia times in an intestinal IRI model in mice. Adult male Balb/c mice were divided into 4 groups that differed in intestinal ischemia time: G1, 30; minutes; G2, 35 minutes; G3, 40 minutes; and G4, 45 minutes. Histological evaluation showed average Park scores as follows: G1 0.6 Ϯ 0.55; G2 1.8 Ϯ 0.45; G3 4.8 Ϯ 2.25; and G4 5 Ϯ 1.79. All animals from G1 survived 30 hours. G2 animals showed intermediate behavior with all succumbing between 18 and 30 hours postprocedure. G3 and G4 displayed similar survival results with animals succumbing before 6 hours after intestinal reperfusion. These data showed that Park index scores of 3 or higher were related to early death. We concluded that the 5 minutes between 35 and 40 minutes is the critical limit, after which all mice die after reperfusion. This result may represent a valuable tool for future research in mice. Address reprint requests to Pablo Luis Stringa, Instituto de Transplante Multiorgánico Fundación Favaloro, Avenida Belgrano 1782 (7 no piso), CABA (1093),

Transplantation Proceedings, 2013

The intestine is highly sensitive to ischemia-reperfusion injury (IRI), a phenomenon occurring in... more The intestine is highly sensitive to ischemia-reperfusion injury (IRI), a phenomenon occurring in different intestinal diseases. Several strategies to mitigate IRI are in experimental stages; unfortunately, no consensus has been reached about the most appropriate one. We report a protocol to study ischemic preconditioning (IPC) evaluation in mice and to combine IPC and tacrolimus (TAC) pretreatment in a warm ischemia model. Mice were divided into treated (IPC, TAC, and IPC þ TAC) and untreated groups before intestinal ischemia. IPC, TAC, and IPC þ TAC groups were able to decrease postreperfusion nitrites levels (P < .05). IPC-containing groups had a major beneficial effect by preserving the integrity of the intestinal histology (P < .05) and improving animal survival (P < .002) compared with TAC alone or the untreated group. The IPC þ TAC group was the only one that showed significant improvement in lung histological analysis (P < .05). The TAC and IPC þ TAC groups down-regulated intestinal expression of interleukin (II)-6 and IL1b more than 10-fold compared with the control group. Although IPC and TAC alone reduced intestinal IRI, the used of a combined therapy produced the most significant results in all the local and distant evaluated parameters.