Shannon Lee Reed - Academia.edu (original) (raw)

Papers by Shannon Lee Reed

International Journal of Morphology, 2008

The digital flexor muscles of the thoracic limb of four llamas were dissected and illustrated to ... more The digital flexor muscles of the thoracic limb of four llamas were dissected and illustrated to provide data about the suspensory (support) apparatus and weight bearing structures. An extensive literature search was performed and yielded incomplete information about these anatomical structures. The popularity of the llama world wide as a domesticated animal used for show and fiber has increased in the recent years. It is helpful to describe the anatomy fully to aid in understanding of the species and treatment of pathologic conditions. The description of the anatomical structures and the original illustrations demonstrate genuine peculiarities and differences between the llama and domestic ruminants. In llamas, the three heads of the deep digital flexor muscle (DDF) originate and connect with each other in a very peculiar combination, with one tendon receiving an attachment from the flexor carpi ulnaris muscle (FCU). The superficial digital flexor muscle (SDF) has a thin tendon which is fused with the palmar fascia and then broadens. There are no interflexor muscles. Additionally, unexpected lumbricalis muscles are found in the distal limb and vary in number between the fore and hind limb. The anatomy of the suspensory apparatus in the thoracic limb is evaluated in this paper.

Veterinary Surgery, 2007

Objective-To evaluate closure strength (in vitro bursting pressure) of jejunal enterotomies in ll... more Objective-To evaluate closure strength (in vitro bursting pressure) of jejunal enterotomies in llamas. Study Design-In vitro experimental study. Sample Population-Jejunal specimens (n ¼ 72) from 6 llamas. Methods-Differences in bursting pressures and luminal diameters were compared between 2 layer enterotomy closures with an initial full thickness simple continuous pattern oversewn with either a continuous Lembert or Cushing suture pattern using 3 sizes (2-0, 3-0, 4-0) of polyglactin 910 and polydioxanone. Results-Bursting pressures were significantly higher for enterotomies closed with polydioxanone than polyglactin 910, independent of suture size, but there was no difference between Lembert and Cushing oversew patterns. Use of a Lembert pattern reduced intestinal diameter more than a Cushing pattern regardless of suture material or size. Conclusions-Although polydioxanone resisted higher bursting pressures than polyglactin 910, both suture materials should be considered satisfactory for jejunal enterotomy closure in llamas based on typical intraluminal pressures expected in clinical patients. The optimal oversew pattern may be continuous Cushing to maximize the luminal diameter in small intestinal enterotomy closures. Clinical Relevance-In vitro bursting pressures may help to predict which enterotomy sites would leak post-operatively, although further studies are necessary to determine the outcome in clinical patients.

Journal of the American Veterinary Medical Association, 2008

P eritoneal fluid analysis has been used in many species to diagnose abdominal disorders, includi... more P eritoneal fluid analysis has been used in many species to diagnose abdominal disorders, including gastrointestinal diseases, uterine diseases, bacterial infections, splenic or hepatic torsion or rupture, urinary tract leakage, neoplasia, and pancreatitis. Although reported occasionally, 1-9 this tool historically has been underused in New World camelids because of lack of reference values and the perception that adequate volumes of uncontaminated sample were difficult to obtain, or that the collection technique could lead to health complications for the patient. Similar to cattle, abdominocentesis performed in the cranioventral region of the abdomen in camelids bore the risk of puncture into the gastrointestinal tract or interference from the omentum, and unlike cattle, camelids appeared to deal poorly with accidental abdominal contamination. As a result, prominent reference works on New World camelids contain no information on peritoneal fluid values or suggest that the values presented are not based on a comprehensive study. 3,4 The purpose of the study reported here was to describe a technique for abdominocentesis in camelids

The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 1998

Studies of estrogen effects on growth hormone (GH) and its pulsatile release in postmenopausal wo... more Studies of estrogen effects on growth hormone (GH) and its pulsatile release in postmenopausal women have typically utilized estrogen replacement therapy (ERT) of relatively short duration (days to weeks). The purpose of this study was to compare GH measures from healthy postmenopausal women who were on oral ERT for 3 years or more (n = 24; mean ERT duration = 16.1 years) with women not on ERT (NERT; n = 40). Blood samples were drawn remotely every 20 minfor 24 h and then analyzed for mean 24-h GH, mean GH during sleep, and mean 24-h insulin-like growth factor-l (IGF-I). GH peak analyses were also performed. Mean 24-h GH and GH during sleep were significantly higher and IGF-I was significantly lower in ERT women compared with NERT women. In addition, use of long-term ERT was associated with more GH peaks relative to women not on ERT, but no change in GH peak amplitude or area. GH was not related to age in either group. GH was strongly and negatively correlated with measures of adiposity in NERT women but not in ERT women. In conclusion, long-term oral ERT is associated with increased circulating GH and decreased IGF-I levels, even after many years of treatment.

Journal of Clinical Investigation, 1995

Infection with the protozoan parasite Entamoeba histolytica results in a high mortality worldwide... more Infection with the protozoan parasite Entamoeba histolytica results in a high mortality worldwide. To initiate infection, E. histolytica trophozoites in the bowel lumen penetrate the epithelium, and cause extensive lysis of host cells. The acute amebic lesions in animal models are characterized by infiltration with inflammatory cells, particularly neutrophils. The acute host response is likely important for determining whether the infection will spread systemically, but little is known regarding the signals which initiate an acute inflammatory response to E. histolytica. In the studies reported herein, we used an in vitro model system to define the proinflammatory signals produced by epithelial and other host cells in response to infection with E. histolytica trophozoites. Coculture of human epithelial and stromal cells and cell lines with trophozoites is shown to increase expression and secretion of an array of chemoattractant and proinflammatory cytokines, including IL-8, GROa, GM-CSF, IL-la, and IL-6. Moreover, high-level secretion of those cytokines is regulated by the paracrine action of cytolytically released IL-la. A second mechanism for trophozoite-induced IL-8 production involves trophozoite-target cell contact via a galactose-inhibitable amebic adherence protein, and appears to be mediated through increased intracellular calcium levels. These studies define novel mechanisms through which acute inflammation can be initiated in the host in response to a cytolytic pathogen, such as E. histolytica.

Journal of Biological Chemistry, 2010

Entamoeba histolytica cysteine proteinases (EhCPs) play a key role in disrupting the colonic epit... more Entamoeba histolytica cysteine proteinases (EhCPs) play a key role in disrupting the colonic epithelial barrier and the innate host immune response during invasion of E. histolytica, the protozoan cause of human amebiasis. EhCPs are encoded by 50 genes, of which ehcp4 (ehcp-a4) is the most up-regulated during invasion and colonization in a mouse cecal model of amebiasis. Up-regulation of ehcp4 in vivo correlated with our finding that co-culture of E. histolytica trophozoites with mucin-producing T84 cells increased ehcp4 expression up to 6-fold. We have expressed recombinant EhCP4, which was autocatalytically activated at acidic pH but had highest proteolytic activity at neutral pH. In contrast to the other amebic cysteine proteinases characterized so far, which have a preference for arginine in the P2 position, EhCP4 displayed a unique preference for valine and isoleucine at P2. This preference was confirmed by homology modeling, which revealed a shallow, hydrophobic S2 pocket. Endogenous EhCP4 localized to cytoplasmic vesicles, the nuclear region, and perinuclear endoplasmic reticulum (ER). Following co-culture with colonic cells, EhCP4 appeared in acidic vesicles and was released extracellularly. A specific vinyl sulfone inhibitor, WRR605, synthesized based on the substrate specificity of EhCP4, inhibited the recombinant enzyme in vitro and significantly reduced parasite burden and inflammation in the mouse cecal model. The unique expression pattern, localization, and biochemical properties of EhCP4 could be exploited as a potential target for drug design. Entamoeba histolytica is the causative protozoan parasite of amebic colitis and liver abscesses and the second leading cause of death from parasitic diseases (1). Invasive E. histolytica trophozoites secrete 10-1,000-fold more cysteine proteinases than non-invasive Entamoeba dispar (2), whereas EhCP 2-deficient trophozoites demonstrate reduced virulence in animal models (3). During amebic invasion, EhCPs degrade the mucus barrier and destroy the extracellular matrix (4) underlying the epithelium, thereby causing epithelial detachment and ulceration (4, 5). Amebic penetration through ulcers facilitates entry into the mucosa and subsequently spread to the liver (3-5). Furthermore, EhCPs interrupt the function of the host immune system by cleaving immune molecules, including IgA and IgG (6, 7), processing complement C3 (2) and inactivating complement C3a and C5a (8). They also generate mature IL-1␤ from pro-IL-1␤ (9) but inactivate pro-IL-18 (10). These alternations of the immune response contribute to ineffective host defenses and thereby excessive inflammation and tissue damage. Genome-wide homology searches have identified 50 E. histolytica genes encoding cysteine proteases (11, 12), most of which belong to the C1 papain superfamily. These enzymes are expressed as zymogens with a hydrophobic pre-domain of 12-20 residues, a pro-domain of 55-148 residues, a catalytic domain of 190-488 residues, and six cysteine residues that form the disulfide bridges to stabilize the tertiary structure (13, 14). The EhCPs that have been characterized to date include EhCP1 (EhCP-A1) (15, 16), EhCP2 (EhCP-A2) (14), EhCP3 (EhCP-A3) (10, 14), EhCP5 (EhCP-A5) (15, 17), and EhCP112 (EhCP-B9) (18). These enzymes all undergo autocatalytic activation in which the inhibitory pro-domain is cleaved from the zymogen. They also have a cathepsin L-like structure, but like cathepsin B, these enzymes can also accommodate Arg at P2 (14). Among the remaining EhCPs,

Journal of Biological Chemistry, 2006

Cysteine proteases play key roles in apicomplexan invasion, organellar biogenesis, and intracellu... more Cysteine proteases play key roles in apicomplexan invasion, organellar biogenesis, and intracellular survival. We have now characterized five genes encoding papain family cathepsins from Toxoplasma gondii, including three cathepsin Cs, one cathepsin B, and one cathepsin L. Unlike endopeptidases cathepsin B and L, T. gondii cathepsin Cs are exopeptidases and remove dipeptides from unblocked N-terminal substrates of proteins or peptides. TgCPC1 was the most highly expressed cathepsin mRNA in tachyzoites (by real-time PCR), but three cathepsins, TgCPC1, TgCPC2, and TgCPB, were undetectable in in vivo bradyzoites. The specific cathepsin C inhibitor, Gly-Phe-dimethylketone, selectively inhibited the TgCPCs activity, reducing parasite intracellular growth and proliferation. The targeted disruption of TgCPC1 does not affect the invasion and growth of tachyzoites as TgCPC2 is then up-regulated and may substitute for TgCPC1. TgCPC1 and TgCPC2 localize to constitutive secretory vesicles of tachyzoites, the dense granules. T. gondii cathepsin Cs are required for peptide degradation in the parasitophorous vacuole as the degradation of the marker protein, Escherichia coli ␤-lactamase, secreted into the parasitophorous vacuole of transgenic tachyzoites was completely inhibited by the cathepsin C inhibitor. Cathepsin C inhibitors also limited the in vivo infection of T. gondii in the chick embryo model of toxoplasmosis. Thus, cathepsin Cs are critical to T. gondii growth and differentiation, and their unique specificities could be exploited to develop novel chemotherapeutic agents.

American Journal of Veterinary Research, 2008

Objective—To determine the effectiveness of administering multiple doses of phenylbutazone alone ... more Objective—To determine the effectiveness of administering multiple doses of phenylbutazone alone or a combination of phenylbutazone and flunixin meglumine to alleviate lameness in horses. Animals—29 adult horses with naturally occurring forelimb and hind limb lameness. Procedures—Lameness evaluations were performed by use of kinematic evaluation while horses were trotting on a treadmill. Lameness evaluations were performed before and 12 hours after administration of 2 nonsteroidal anti-inflammatory drug (NSAID) treatment regimens. Phenylbutazone paste was administered at approximately 2.2 mg/kg, PO, every 12 hours for 5 days, or phenylbutazone paste was administered at approximately 2.2 mg/kg, PO, every 12 hours for 5 days in combination with flunixin meglumine administered at 1.1 mg/kg, IV, every 12 hours for 5 days. Results—Alleviation of lameness was greater after administration of the combination of NSAIDs than after oral administration of phenylbutazone alone. Improvement in ho...

American Journal of Veterinary Research, 2013

Objective—To characterize serum trace mineral, sex steroid hormone, and vitamin D concentrations ... more Objective—To characterize serum trace mineral, sex steroid hormone, and vitamin D concentrations and identify factors associated with metacarpophalangeal and metatarsophalangeal hyperextension in llamas and alpacas. Samples—Serum samples from 79 llamas and 15 alpacas and owner survey data for 573 llamas and 399 alpacas. Procedures—Serum samples were stored at −20°C until analysis and were evaluated for trace mineral, vitamin D, estradiol, progesterone, and testosterone concentrations. Information regarding age of onset, number of affected animals in herd, feed and supplements given, type of housing, and management practices was obtained in an owner survey. Results—Higher serum zinc and iron concentrations were associated with metacarpophalangeal and metatarsophalangeal hyperextension in camelids, compared with controls. In summer and fall months, vitamin D concentrations were significantly higher in affected camelids than controls. Overall prevalence was 13.3% in llamas, compared wi...

American Journal of Veterinary Research, 2006

Objective—To assess effects of treatment with phenylbutazone (PBZ) or a combination of PBZ and fl... more Objective—To assess effects of treatment with phenylbutazone (PBZ) or a combination of PBZ and flunixin meglumine in horses. Animals—24 adult horses. Procedure—13 horses received nonsteroidal antiinflammatory drugs (NSAIDs) in a crossover design. Eleven control horses were exposed to similar environmental conditions. Treated horses received PBZ (2.2 mg/kg, PO, q 12 h, for 5 days) and a combination of PBZ and flunixin meglumine (PBZ, 2.2 mg/kg, PO, q 12 h, for 5 days; flunixin meglumine, 1.1 mg/kg, IV, q 12 h, for 5 days). Serum samples were obtained on day 0 (first day of treatment) and day 5, and total protein, albumin, and globulin were measured. Results—1 horse was euthanatized with severe hypoproteinemia, hypoalbuminemia, and colitis during the combination treatment. Comparisons revealed no significant difference between control horses and horses treated with PBZ alone. There was a significant difference between control and treated horses when administered a combination of PBZ a...

American Journal of Veterinary Research, 2010

Objective—To determine the molecular and histologic characteristics of hyperextension of the meta... more Objective—To determine the molecular and histologic characteristics of hyperextension of the metacarpophalangeal and metatarsophalangeal joints in adult llamas. Animals—12 adult llamas (6 with bilateral hyperextension of the metacarpophalangeal or metatarsophalangeal joints [affected] and 6 age- and sex-matched clinically normal control llamas). Procedures—Llamas were euthanized, and specimens of superficial digital flexor tendon, deep digital flexor tendon, and suspensory ligament were obtained from 4 areas and snap frozen in liquid nitrogen or suspended in neutral-buffered 10% formalin. Histologic evaluation of collagen fiber orientation, elastin content, and proteoglycan content was performed by use of Masson trichrome, picrosirius red, Verhoeff, and Alcian blue stains. Total RNA was isolated from frozen suspensory ligament specimens. Gene expression of collagen types I and III, lysyl oxidase, and matrix metalloproteinase-13 was evaluated with a real-time quantitative reverse tra...

American Journal of Veterinary Research, 2011

Objective—To evaluate molecular and histologic characteristics of the superficial digital flexor ... more Objective—To evaluate molecular and histologic characteristics of the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), and suspensory ligament (SL) and assess trace-mineral concentrations in serum, liver, and hair of juvenile llamas with metacarpophalangeal and metatarsophalangeal joint hyperextension. Animals—12 juvenile llamas (6 with bilateral hyperextension of metacarpophalangeal joints, metatarsophalangeal joints, or both and 6 clinically normal control llamas). Procedures—Radiography and ultrasonography of metacarpophalangeal and metatarsophalangeal regions were performed. Llamas were euthanized, and SDFT, DDFT, and SL samples were collected for histologic evaluation of collagen and elastin content and orientation, proteoglycan content, and collagen type III immunohistochemistry. Total RNA was isolated from SL tissue, and gene expression of collagen types I and III, lysyl oxidase, and matrix metalloproteinase-13 was evaluated via real-time quantitat...

American Journal of Veterinary Research, 2007

Objective—To determine the morphologic and biochemical characteristics of hyperextension of the m... more Objective—To determine the morphologic and biochemical characteristics of hyperextension of the metacarpophalangeal and metatarsophalangeal joints in llamas. Animals—12 adult llamas (6 with bilateral hyperextension of the metacarpophalangeal or metatarsophalangeal joints and 6 age- and sex-matched control llamas). Procedures—Llamas were evaluated by use of lameness examination, ultrasonography, and radiography. A CBC, serum biochemical analysis, and determination of concentrations of trace minerals in serum and liver samples were performed. Llamas were euthanized, and samples of the superficial digital flexor tendon, deep digital flexor tendon, and suspensory ligament were obtained from 4 areas and snap-frozen in liquid nitrogen or suspended in neutral-buffered 10% formalin. Immunohistochemical evaluation of collagen types I and III and assays for measurement of lysyl oxidase activity were performed. Results—2 affected llamas had a visible gait deficit associated with metacarpophala...