A. Mika - Academia.edu (original) (raw)

Papers by A. Mika

Research paper thumbnail of Changes of bioelectrical activity in cervical paraspinal muscle during gait in low and high heel shoes

Acta of bioengineering and biomechanics / Wrocław University of Technology, 2011

High heel footwear may be destructive for the spine because of an increased erector spinae muscle... more High heel footwear may be destructive for the spine because of an increased erector spinae muscle bioelectrical activity and increased ground reaction forces affecting lower limbs and the spine. The aim of this study was to evaluate the changes of bioelectrical activity in cervical paraspinal muscle during gait in low and in high heel shoes in different age groups. In 31 women aged 20-25 years and in 15 women aged 45-55 years without neck pain, the bioelectrical activity of the cervical paraspinal muscle was assessed during gait on flat surface with natural speed in three conditions: without shoes, in low (4 cm) and in high (10 cm) heel shoes. Higher bioelectrical activity cervical paraspinal muscle was noted during gait in high heel shoes in comparison to gait without shoes. The changes were more pronounced in the group of subjects aged 45-55 years. The prolonged wearing of shoes with stiletto type heels by individuals without neck pain is not safe for their spine and may lead to c...

Research paper thumbnail of Evaluation of the influence of low and high heel shoes on erector spine muscle bioelectrical activity assessed at baseline and during movement

Med Rehabil, 2009

Introduction: Back pain due to the wearing of high heel shoes may result from increased erector s... more Introduction: Back pain due to the wearing of high heel shoes may result from increased erector spine activity and also from higher proximal ground reaction forces or center of body mass dislocation. Aim: The assessment of changes in the erector spine muscle due to the non-physiological foot position in low and high heel shoes. Material and Methods: In 31 women aged 20-25 years (height 167, 6±5.8 cm; weight 60, 35±6, 49 kg) without back pain, the bioelectrical activity of the erector spine muscle was assessed. A ...

Research paper thumbnail of The Genetic Legacy of Paleolithic Homo sapiens sapiens in Extant Europeans: A Y Chromosome Perspective

Science, 2000

A genetic perspective of human history in Europe was derived from 22 binary markers of the nonrec... more A genetic perspective of human history in Europe was derived from 22 binary markers of the nonrecombining Y chromosome (NRY). Ten lineages account for >95% of the 1007 European Y chromosomes studied. Geographic distribution and age estimates of alleles are compatible with two Paleolithic and one Neolithic migratory episode that have contributed to the modern European gene pool. A significant correlation between the NRY haplotype data and principal components based on 95 protein markers was observed, indicating the effectiveness of NRY binary polymorphisms in the characterization of human population composition and history.

Research paper thumbnail of Diagnostische und prognostische Implikationen des ersten epileptischen Anfalls im Erwachsenenalter

Fortschritte der Neurologie · Psychiatrie, 1994

Actual epidemiological studies show a prevalence rate for active epilepsy in 0.5-1%, whereas sing... more Actual epidemiological studies show a prevalence rate for active epilepsy in 0.5-1%, whereas single seizures occur in up to 5% of the general population. Assessment of the significance of first epileptic reaction requires precise definition and classification of the episode, a careful analysis of the entire context including thorough case history, and indirect anamnesis. The value of EEG-techniques for this issue is part of a controversial discussion. By means of cranial computerized tomography (cCT), brain tumours were detected as structural correlate in 5 to 16% of first-seizure-patients. In recent studies, estimated risk of seizure recurrence after first unprovoked seizure ranged from 27% to 78%: most of the relapses were observed in the first 6 months after the first event. The wide range of relapse rates is due to the divergent methodological designs (retro- versus prospective design, selection of patients, length of time before study entry) in the different studies. There are conflicting results concerning risk factors and predictive value of the following variables: pathology in the neurostatus, focal seizure type or Todd's paresis, history of febrile seizures, symptomatic genesis, and specific epileptic potentials and time of day of seizure event. In an actual metaanalysis of recent studies, seizure etiology and EEG were the strongest predictors of recurrence. The preliminary results of our prospective study with a strict protocol and first-seizure-design are presented: we observed a seizure relapse in 26.7% of 78 adult patients (age range: 17-84 years) after a mean latency of 4.4 months. Until now, there is no evidence for potential predictors of seizure recurrence.(ABSTRACT TRUNCATED AT 250 WORDS)

Research paper thumbnail of MS363 CHANGES OF sEMG ACTIVITY IN PROXIMAL AND DISTAL LEG MUSCLES IN PATIENTS WITH CLAUDICATION OVER 12-WEEK TREADMILL TRAINING – THE PILOT STUDY

Atherosclerosis Supplements, 2010

The present era of the heath care places major emphasis on significantly reducing cost and resour... more The present era of the heath care places major emphasis on significantly reducing cost and resource utilization while maintaining quality of care and patient satisfaction. Off-pump coronary artery bypass surgery (OPCAB) avoids the potential complications of cardiopulmonary bypass, How ever; its acceptance depends on medical and economic out come. The aim of this study was to compare medical and economic out come of off pump and on pump surgery. Methods: 304 patients undergoing first time coronary artery bypass surgery were randomized in to conventional on-pump and off pump group. Variables and fixed direct costs were obtained for each group and the data were analyzed using parametric methods. Results: There was no difference between the groups with respect to pre-and intraoperative patient variables. OPCAB significantly reduced the incidence of postoperative transfusion requirement (p < 0.05) and showed a trend toward reduced morbidity which did not reach statistical significant (p > 0.05). Although the use of an off pump procedure was associated with a decrease in risk adjusted operative mortality from 2.6% with conventional CABG to 0.7% in the off pump group but both off pump and on pump procedures produced excellent early clinical results. There were no statistically significant difference in surgical reexploration, length of stay and costs two groups. Conclusion: Based on the results of this study there was no significant difference between OPCAB and on-pump CABG.

Research paper thumbnail of Changes of bioelectrical activity in cervical paraspinal muscle during gait in low and high heel shoes

Acta of bioengineering and biomechanics / Wrocław University of Technology, 2011

High heel footwear may be destructive for the spine because of an increased erector spinae muscle... more High heel footwear may be destructive for the spine because of an increased erector spinae muscle bioelectrical activity and increased ground reaction forces affecting lower limbs and the spine. The aim of this study was to evaluate the changes of bioelectrical activity in cervical paraspinal muscle during gait in low and in high heel shoes in different age groups. In 31 women aged 20-25 years and in 15 women aged 45-55 years without neck pain, the bioelectrical activity of the cervical paraspinal muscle was assessed during gait on flat surface with natural speed in three conditions: without shoes, in low (4 cm) and in high (10 cm) heel shoes. Higher bioelectrical activity cervical paraspinal muscle was noted during gait in high heel shoes in comparison to gait without shoes. The changes were more pronounced in the group of subjects aged 45-55 years. The prolonged wearing of shoes with stiletto type heels by individuals without neck pain is not safe for their spine and may lead to c...

Research paper thumbnail of Salicylic acid changes the properties of extracellular peroxidase activity secreted from wounded wheat (Triticum aestivum L.) roots

Protoplasma, 2003

Wheat ( Triticum aestivum L.) roots released proteins showing peroxidase activity in the apoplast... more Wheat ( Triticum aestivum L.) roots released proteins showing peroxidase activity in the apoplastic solution in response to wound stress. Preincubation of excised roots with 1 mM salicylic acid at pH 7.0 enhanced the guaiacol peroxidase activity of the extracellular solution (so-called extracellular peroxidase). The soluble enzymes were partially purified by precipitation with ammonium sulfate followed by size exclusion and ion exchange chromatography. Despite an increase in the total activity of secreted peroxidase induced by pretreatment of excised roots with salicylic acid, the specific activity of the partially purified protein was significantly lower compared to that of the control. Purification of the corresponding proteins by ion exchange chromatography indicates that several isoforms of peroxidase occurred in both control and salicylic acid-treated samples. The activities of the extracellular peroxidases secreted by the salicylic acid-treated roots responded differently to c...

Research paper thumbnail of Recovery after chronic stress within spatial reference and working memory domains: correspondence with hippocampal morphology

European Journal of Neuroscience, 2011

Chronic stress results in reversible spatial learning impairments in the Morris water maze that c... more Chronic stress results in reversible spatial learning impairments in the Morris water maze that correspond with hippocampal CA3 dendritic retraction in male rats. Whether chronic stress impacts different types of memory domains, and whether these can similarly recover, is unknown. This study assessed the effects of chronic stress with and without a post-stress delay to evaluate learning and memory deficits within two memory domains, reference and working memory, in the radial arm water maze (RAWM). Three groups of 5-month-old male Sprague-Dawley rats were either not stressed [control (CON)], or restrained (6 h/day for 21 days) and then tested on the RAWM either on the next day [stress immediate (STR-IMM)] or following a 21-day delay [stress delay (STR-DEL)]. Although the groups learned the RAWM task similarly, groups differed in their 24-h retention trial assessment. Specifically, the STR-IMM group made more errors within both the spatial reference and working memory domains, and these deficits corresponded with a reduction in apical branch points and length of hippocampal CA3 dendrites. In contrast, the STR-DEL group showed significantly fewer errors in both the reference and working memory domains than the STR-IMM group. Moreover, the STR-DEL group showed better RAWM performance in the reference memory domain than did the CON group, and this corresponded with restored CA3 dendritic complexity, revealing long-term enhancing actions of chronic stress. These results indicate that chronic stress-induced spatial working and reference memory impairments, and CA3 dendritic retraction, are reversible, with chronic stress having lasting effects that can benefit spatial reference memory, but with these lasting beneficial effects being independent of CA3 dendritic complexity.

Research paper thumbnail of Extracellular superoxide production in the liverwort Dumortiera

Research paper thumbnail of Chronic stress impairs prefrontal cortex-dependent response inhibition and spatial working memory

Behavioral Neuroscience, 2012

Chronic stress leads to neurochemical and structural alterations in the prefrontal cortex (PFC) t... more Chronic stress leads to neurochemical and structural alterations in the prefrontal cortex (PFC) that correspond to deficits in PFC-mediated behaviors. The present study examined the effects of chronic restraint stress on response inhibition (using a response-withholding task, the fixed-minimum interval schedule of reinforcement, or FMI), and working memory (using a radial arm water maze, RAWM). Adult male Sprague-Dawley rats were first trained on the RAWM and subsequently trained on FMI. After acquisition of FMI, rats were assigned to a restraint stress (6h/d/28d in wire mesh restrainers) or control condition. Immediately after chronic stress, rats were tested on FMI and subsequently on RAWM. FMI results suggest that chronic stress reduces response inhibition capacity and motivation to initiate the task on selective conditions when sucrose reward was not obtained on the preceding trial. RAWM results suggest that chronic stress produces transient deficits in working memory without altering previously consolidated reference memory. Behavioral measures from FMI failed to correlate with metrics from RAWM except for one in which changes in FMI timing imprecision negatively correlated with changes in RAWM working memory errors for the controls, a finding that was not observed following chronic stress. Fisher's r-to-z transformation revealed no significant differences between control and stress groups with correlation coefficients. These findings are the first to show that chronic stress impairs both response inhibition and working memory, two behaviors that have never been directly compared within the same animals after chronic stress, using FMI, an appetitive task, and RAWM, a nonappetitive task.

Research paper thumbnail of Host complement inhibition links scabies and associated GAS skin disease

Research paper thumbnail of Complement Inhibitors from Scabies Mites Promote Streptococcal Growth – A Novel Mechanism in Infected Epidermis?

PLoS Neglected Tropical Diseases, 2012

Background: Scabies is highly prevalent in socially disadvantaged communities such as indigenous ... more Background: Scabies is highly prevalent in socially disadvantaged communities such as indigenous populations and in developing countries. Generalized itching causes discomfort to the patient; however, serious complications can occur as a result of secondary bacterial pyoderma, commonly caused by Streptococcus pyogenes (GAS) or Staphylococcus aureus. In the tropics, skin damage due to scabies mite infestations has been postulated to be an important link in the pathogenesis of disease associated with acute rheumatic fever and heart disease, poststreptococcal glomerulonephritis and systemic sepsis. Treatment of scabies decreases the prevalence of infections by bacteria. This study aims to identify the molecular mechanisms underlying the link between scabies and GAS infections.

Research paper thumbnail of Complement evasion of the scabies mite Sarcoptes scabiei

Molecular Immunology, 2009

Research paper thumbnail of Scabies mite complement inhibitors promote growth of Group A Streptococcus

Molecular Immunology, 2011

Research paper thumbnail of Novel scabies mite serpins inhibit the three pathways of the human complement system

Molecular Immunology, 2011

Scabies is a parasitic infestation of the skin by the mite Sarcoptes scabiei that causes signific... more Scabies is a parasitic infestation of the skin by the mite Sarcoptes scabiei that causes significant morbidity worldwide, in particular within socially disadvantaged populations. In order to identify mechanisms that enable the scabies mite to evade human immune defenses, we have studied molecules associated with proteolytic systems in the mite, including two novel scabies mite serine protease inhibitors (SMSs) of the serpin superfamily. Immunohistochemical studies revealed that within mite-infected human skin SMSB4 (54 kDa) and SMSB3 (47 kDa) were both localized in the mite gut and feces. Recombinant purified SMSB3 and SMSB4 did not inhibit mite serine and cysteine proteases, but did inhibit mammalian serine proteases, such as chymotrypsin, albeit inefficiently. Detailed functional analysis revealed that both serpins interfered with all three pathways of the human complement system at different stages of their activation. SMSB4 inhibited mostly the initial and progressing steps of t...

Research paper thumbnail of Anti-complement activity of scabies mite serine proteases

Molecular Immunology, 2011

Research paper thumbnail of Lectin pathway inhibition by parasitic scabies mites: Molecular characterisation of host–pathogen immune mechanisms

Molecular Immunology, 2013

Research paper thumbnail of Experimental analysis, modeling, and theoretical design of McMaster pore-filled nanofiltration membranes

Journal of Membrane Science, 2004

Research paper thumbnail of Pore-filled nanofiltration membranes based on poly(2-acrylamido-2-methylpropanesulfonic acid) gels

Journal of Membrane Science, 2005

Strong polyacid gel-filled membranes have been prepared by UV-initiated copolymerization of 2-acr... more Strong polyacid gel-filled membranes have been prepared by UV-initiated copolymerization of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and N,N -methylenebisacrylamide within the pores of a microporous polypropylene (PP) substrate. These poly(2-acrylamido-2methylpropanesulfonic acid) (PAMPS) gel-filled membranes were readily prepared with predictable amounts of the incorporated gel polymer (mass gain, MG) provided that threshold values of the degree of cross-linking and monomer concentration were exceeded. Most of the membranes showed large dimensional changes, particularly in their thickness on incorporation of the PAMPS. These changes were related to the amount of PAMPS incorporated into the membranes. In order to determine the polymer volume fractions of the incorporated gels, the partial specific volume of PAMPS (0.575 cm 3 /g) was obtained from density measurements using pycnometry. As a result of increase in thickness (volume) of the membranes, the polymer volume fractions of the PAMPS pore-filling gels were limited to values between 0.01 and 0.06, relatively low values compared to values achieved with other gel-filled membranes based on the same substrate. The Darcy permeability of PAMPS gel-filled membranes exhibits a typical relationship with polymer volume fraction, but the absolute values obtained are much lower than those of other gel-filled membranes previously studied. The lower permeability could be attributed to tightly bound water molecules along polymer chains, which effectively enlarges the hydrodynamic size of polymer chains and narrows the channels for water transport. Using the sphere model based on the Odijk's theory of semidilute polyelectrolyte solutions, the Darcy permeability of PAMPS gel-filled membranes could be calculated with good precision.

Research paper thumbnail of Chemical valves based on poly(4-vinylpyridine)-filled microporous membranes

Journal of Membrane Science, 1999

Microporous membranes containing poly(4-vinylpyridine) anchored within the pores exhibit very lar... more Microporous membranes containing poly(4-vinylpyridine) anchored within the pores exhibit very large chemical valve effects with pressure-driven permeability changing by more than three orders of magnitude as a function of pH. The factors affecting the magnitude of this valve have been examined with a series of well characterized, poly(4-vinylpyridine)-modi®ed, microporous polypropylene membranes. The permeability of these membranes to HCl/H 2 O at different pHs was measured as a function of pore size of the starting base membrane and the amount of poly(4-vinylpyridine) anchored within the pores. An analysis of these results shows that the magnitude of the chemical valve is largely determined by the permeability of the membranes in their open-valve states, i.e., high pH. While the magnitude of the chemical valve effect exhibited by the membranes varied, the pH at which the valve closed was in each case found to be similar and independent of pore size of the starting membrane or amount of poly(4-vinylpyridine) anchored within the pores. The permeability of the membranes at low pH (when the anchored poly(4-vinylpyridine) is ionized) was examined using two existing models of hydrodynamic permeability, namely, the pressure-driven¯ow through a right-cylinder pore partly obscured by a graft layer of a hydrodynamic thickness L H (brush model) and the hydrodynamic¯ow through supported hydrogels (pore-®lled model). The theory of polyelectrolytes in the semi-dilute region was used to estimate the chain parameters of the incorporated polyelectrolyte. The results obtained show that the applicability of each model depends on the pore size of the substrate membranes and the molecular weight of the polyelectrolyte. #

Research paper thumbnail of Changes of bioelectrical activity in cervical paraspinal muscle during gait in low and high heel shoes

Acta of bioengineering and biomechanics / Wrocław University of Technology, 2011

High heel footwear may be destructive for the spine because of an increased erector spinae muscle... more High heel footwear may be destructive for the spine because of an increased erector spinae muscle bioelectrical activity and increased ground reaction forces affecting lower limbs and the spine. The aim of this study was to evaluate the changes of bioelectrical activity in cervical paraspinal muscle during gait in low and in high heel shoes in different age groups. In 31 women aged 20-25 years and in 15 women aged 45-55 years without neck pain, the bioelectrical activity of the cervical paraspinal muscle was assessed during gait on flat surface with natural speed in three conditions: without shoes, in low (4 cm) and in high (10 cm) heel shoes. Higher bioelectrical activity cervical paraspinal muscle was noted during gait in high heel shoes in comparison to gait without shoes. The changes were more pronounced in the group of subjects aged 45-55 years. The prolonged wearing of shoes with stiletto type heels by individuals without neck pain is not safe for their spine and may lead to c...

Research paper thumbnail of Evaluation of the influence of low and high heel shoes on erector spine muscle bioelectrical activity assessed at baseline and during movement

Med Rehabil, 2009

Introduction: Back pain due to the wearing of high heel shoes may result from increased erector s... more Introduction: Back pain due to the wearing of high heel shoes may result from increased erector spine activity and also from higher proximal ground reaction forces or center of body mass dislocation. Aim: The assessment of changes in the erector spine muscle due to the non-physiological foot position in low and high heel shoes. Material and Methods: In 31 women aged 20-25 years (height 167, 6±5.8 cm; weight 60, 35±6, 49 kg) without back pain, the bioelectrical activity of the erector spine muscle was assessed. A ...

Research paper thumbnail of The Genetic Legacy of Paleolithic Homo sapiens sapiens in Extant Europeans: A Y Chromosome Perspective

Science, 2000

A genetic perspective of human history in Europe was derived from 22 binary markers of the nonrec... more A genetic perspective of human history in Europe was derived from 22 binary markers of the nonrecombining Y chromosome (NRY). Ten lineages account for &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;95% of the 1007 European Y chromosomes studied. Geographic distribution and age estimates of alleles are compatible with two Paleolithic and one Neolithic migratory episode that have contributed to the modern European gene pool. A significant correlation between the NRY haplotype data and principal components based on 95 protein markers was observed, indicating the effectiveness of NRY binary polymorphisms in the characterization of human population composition and history.

Research paper thumbnail of Diagnostische und prognostische Implikationen des ersten epileptischen Anfalls im Erwachsenenalter

Fortschritte der Neurologie · Psychiatrie, 1994

Actual epidemiological studies show a prevalence rate for active epilepsy in 0.5-1%, whereas sing... more Actual epidemiological studies show a prevalence rate for active epilepsy in 0.5-1%, whereas single seizures occur in up to 5% of the general population. Assessment of the significance of first epileptic reaction requires precise definition and classification of the episode, a careful analysis of the entire context including thorough case history, and indirect anamnesis. The value of EEG-techniques for this issue is part of a controversial discussion. By means of cranial computerized tomography (cCT), brain tumours were detected as structural correlate in 5 to 16% of first-seizure-patients. In recent studies, estimated risk of seizure recurrence after first unprovoked seizure ranged from 27% to 78%: most of the relapses were observed in the first 6 months after the first event. The wide range of relapse rates is due to the divergent methodological designs (retro- versus prospective design, selection of patients, length of time before study entry) in the different studies. There are conflicting results concerning risk factors and predictive value of the following variables: pathology in the neurostatus, focal seizure type or Todd&amp;amp;#39;s paresis, history of febrile seizures, symptomatic genesis, and specific epileptic potentials and time of day of seizure event. In an actual metaanalysis of recent studies, seizure etiology and EEG were the strongest predictors of recurrence. The preliminary results of our prospective study with a strict protocol and first-seizure-design are presented: we observed a seizure relapse in 26.7% of 78 adult patients (age range: 17-84 years) after a mean latency of 4.4 months. Until now, there is no evidence for potential predictors of seizure recurrence.(ABSTRACT TRUNCATED AT 250 WORDS)

Research paper thumbnail of MS363 CHANGES OF sEMG ACTIVITY IN PROXIMAL AND DISTAL LEG MUSCLES IN PATIENTS WITH CLAUDICATION OVER 12-WEEK TREADMILL TRAINING – THE PILOT STUDY

Atherosclerosis Supplements, 2010

The present era of the heath care places major emphasis on significantly reducing cost and resour... more The present era of the heath care places major emphasis on significantly reducing cost and resource utilization while maintaining quality of care and patient satisfaction. Off-pump coronary artery bypass surgery (OPCAB) avoids the potential complications of cardiopulmonary bypass, How ever; its acceptance depends on medical and economic out come. The aim of this study was to compare medical and economic out come of off pump and on pump surgery. Methods: 304 patients undergoing first time coronary artery bypass surgery were randomized in to conventional on-pump and off pump group. Variables and fixed direct costs were obtained for each group and the data were analyzed using parametric methods. Results: There was no difference between the groups with respect to pre-and intraoperative patient variables. OPCAB significantly reduced the incidence of postoperative transfusion requirement (p < 0.05) and showed a trend toward reduced morbidity which did not reach statistical significant (p > 0.05). Although the use of an off pump procedure was associated with a decrease in risk adjusted operative mortality from 2.6% with conventional CABG to 0.7% in the off pump group but both off pump and on pump procedures produced excellent early clinical results. There were no statistically significant difference in surgical reexploration, length of stay and costs two groups. Conclusion: Based on the results of this study there was no significant difference between OPCAB and on-pump CABG.

Research paper thumbnail of Changes of bioelectrical activity in cervical paraspinal muscle during gait in low and high heel shoes

Acta of bioengineering and biomechanics / Wrocław University of Technology, 2011

High heel footwear may be destructive for the spine because of an increased erector spinae muscle... more High heel footwear may be destructive for the spine because of an increased erector spinae muscle bioelectrical activity and increased ground reaction forces affecting lower limbs and the spine. The aim of this study was to evaluate the changes of bioelectrical activity in cervical paraspinal muscle during gait in low and in high heel shoes in different age groups. In 31 women aged 20-25 years and in 15 women aged 45-55 years without neck pain, the bioelectrical activity of the cervical paraspinal muscle was assessed during gait on flat surface with natural speed in three conditions: without shoes, in low (4 cm) and in high (10 cm) heel shoes. Higher bioelectrical activity cervical paraspinal muscle was noted during gait in high heel shoes in comparison to gait without shoes. The changes were more pronounced in the group of subjects aged 45-55 years. The prolonged wearing of shoes with stiletto type heels by individuals without neck pain is not safe for their spine and may lead to c...

Research paper thumbnail of Salicylic acid changes the properties of extracellular peroxidase activity secreted from wounded wheat (Triticum aestivum L.) roots

Protoplasma, 2003

Wheat ( Triticum aestivum L.) roots released proteins showing peroxidase activity in the apoplast... more Wheat ( Triticum aestivum L.) roots released proteins showing peroxidase activity in the apoplastic solution in response to wound stress. Preincubation of excised roots with 1 mM salicylic acid at pH 7.0 enhanced the guaiacol peroxidase activity of the extracellular solution (so-called extracellular peroxidase). The soluble enzymes were partially purified by precipitation with ammonium sulfate followed by size exclusion and ion exchange chromatography. Despite an increase in the total activity of secreted peroxidase induced by pretreatment of excised roots with salicylic acid, the specific activity of the partially purified protein was significantly lower compared to that of the control. Purification of the corresponding proteins by ion exchange chromatography indicates that several isoforms of peroxidase occurred in both control and salicylic acid-treated samples. The activities of the extracellular peroxidases secreted by the salicylic acid-treated roots responded differently to c...

Research paper thumbnail of Recovery after chronic stress within spatial reference and working memory domains: correspondence with hippocampal morphology

European Journal of Neuroscience, 2011

Chronic stress results in reversible spatial learning impairments in the Morris water maze that c... more Chronic stress results in reversible spatial learning impairments in the Morris water maze that correspond with hippocampal CA3 dendritic retraction in male rats. Whether chronic stress impacts different types of memory domains, and whether these can similarly recover, is unknown. This study assessed the effects of chronic stress with and without a post-stress delay to evaluate learning and memory deficits within two memory domains, reference and working memory, in the radial arm water maze (RAWM). Three groups of 5-month-old male Sprague-Dawley rats were either not stressed [control (CON)], or restrained (6 h/day for 21 days) and then tested on the RAWM either on the next day [stress immediate (STR-IMM)] or following a 21-day delay [stress delay (STR-DEL)]. Although the groups learned the RAWM task similarly, groups differed in their 24-h retention trial assessment. Specifically, the STR-IMM group made more errors within both the spatial reference and working memory domains, and these deficits corresponded with a reduction in apical branch points and length of hippocampal CA3 dendrites. In contrast, the STR-DEL group showed significantly fewer errors in both the reference and working memory domains than the STR-IMM group. Moreover, the STR-DEL group showed better RAWM performance in the reference memory domain than did the CON group, and this corresponded with restored CA3 dendritic complexity, revealing long-term enhancing actions of chronic stress. These results indicate that chronic stress-induced spatial working and reference memory impairments, and CA3 dendritic retraction, are reversible, with chronic stress having lasting effects that can benefit spatial reference memory, but with these lasting beneficial effects being independent of CA3 dendritic complexity.

Research paper thumbnail of Extracellular superoxide production in the liverwort Dumortiera

Research paper thumbnail of Chronic stress impairs prefrontal cortex-dependent response inhibition and spatial working memory

Behavioral Neuroscience, 2012

Chronic stress leads to neurochemical and structural alterations in the prefrontal cortex (PFC) t... more Chronic stress leads to neurochemical and structural alterations in the prefrontal cortex (PFC) that correspond to deficits in PFC-mediated behaviors. The present study examined the effects of chronic restraint stress on response inhibition (using a response-withholding task, the fixed-minimum interval schedule of reinforcement, or FMI), and working memory (using a radial arm water maze, RAWM). Adult male Sprague-Dawley rats were first trained on the RAWM and subsequently trained on FMI. After acquisition of FMI, rats were assigned to a restraint stress (6h/d/28d in wire mesh restrainers) or control condition. Immediately after chronic stress, rats were tested on FMI and subsequently on RAWM. FMI results suggest that chronic stress reduces response inhibition capacity and motivation to initiate the task on selective conditions when sucrose reward was not obtained on the preceding trial. RAWM results suggest that chronic stress produces transient deficits in working memory without altering previously consolidated reference memory. Behavioral measures from FMI failed to correlate with metrics from RAWM except for one in which changes in FMI timing imprecision negatively correlated with changes in RAWM working memory errors for the controls, a finding that was not observed following chronic stress. Fisher's r-to-z transformation revealed no significant differences between control and stress groups with correlation coefficients. These findings are the first to show that chronic stress impairs both response inhibition and working memory, two behaviors that have never been directly compared within the same animals after chronic stress, using FMI, an appetitive task, and RAWM, a nonappetitive task.

Research paper thumbnail of Host complement inhibition links scabies and associated GAS skin disease

Research paper thumbnail of Complement Inhibitors from Scabies Mites Promote Streptococcal Growth – A Novel Mechanism in Infected Epidermis?

PLoS Neglected Tropical Diseases, 2012

Background: Scabies is highly prevalent in socially disadvantaged communities such as indigenous ... more Background: Scabies is highly prevalent in socially disadvantaged communities such as indigenous populations and in developing countries. Generalized itching causes discomfort to the patient; however, serious complications can occur as a result of secondary bacterial pyoderma, commonly caused by Streptococcus pyogenes (GAS) or Staphylococcus aureus. In the tropics, skin damage due to scabies mite infestations has been postulated to be an important link in the pathogenesis of disease associated with acute rheumatic fever and heart disease, poststreptococcal glomerulonephritis and systemic sepsis. Treatment of scabies decreases the prevalence of infections by bacteria. This study aims to identify the molecular mechanisms underlying the link between scabies and GAS infections.

Research paper thumbnail of Complement evasion of the scabies mite Sarcoptes scabiei

Molecular Immunology, 2009

Research paper thumbnail of Scabies mite complement inhibitors promote growth of Group A Streptococcus

Molecular Immunology, 2011

Research paper thumbnail of Novel scabies mite serpins inhibit the three pathways of the human complement system

Molecular Immunology, 2011

Scabies is a parasitic infestation of the skin by the mite Sarcoptes scabiei that causes signific... more Scabies is a parasitic infestation of the skin by the mite Sarcoptes scabiei that causes significant morbidity worldwide, in particular within socially disadvantaged populations. In order to identify mechanisms that enable the scabies mite to evade human immune defenses, we have studied molecules associated with proteolytic systems in the mite, including two novel scabies mite serine protease inhibitors (SMSs) of the serpin superfamily. Immunohistochemical studies revealed that within mite-infected human skin SMSB4 (54 kDa) and SMSB3 (47 kDa) were both localized in the mite gut and feces. Recombinant purified SMSB3 and SMSB4 did not inhibit mite serine and cysteine proteases, but did inhibit mammalian serine proteases, such as chymotrypsin, albeit inefficiently. Detailed functional analysis revealed that both serpins interfered with all three pathways of the human complement system at different stages of their activation. SMSB4 inhibited mostly the initial and progressing steps of t...

Research paper thumbnail of Anti-complement activity of scabies mite serine proteases

Molecular Immunology, 2011

Research paper thumbnail of Lectin pathway inhibition by parasitic scabies mites: Molecular characterisation of host–pathogen immune mechanisms

Molecular Immunology, 2013

Research paper thumbnail of Experimental analysis, modeling, and theoretical design of McMaster pore-filled nanofiltration membranes

Journal of Membrane Science, 2004

Research paper thumbnail of Pore-filled nanofiltration membranes based on poly(2-acrylamido-2-methylpropanesulfonic acid) gels

Journal of Membrane Science, 2005

Strong polyacid gel-filled membranes have been prepared by UV-initiated copolymerization of 2-acr... more Strong polyacid gel-filled membranes have been prepared by UV-initiated copolymerization of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and N,N -methylenebisacrylamide within the pores of a microporous polypropylene (PP) substrate. These poly(2-acrylamido-2methylpropanesulfonic acid) (PAMPS) gel-filled membranes were readily prepared with predictable amounts of the incorporated gel polymer (mass gain, MG) provided that threshold values of the degree of cross-linking and monomer concentration were exceeded. Most of the membranes showed large dimensional changes, particularly in their thickness on incorporation of the PAMPS. These changes were related to the amount of PAMPS incorporated into the membranes. In order to determine the polymer volume fractions of the incorporated gels, the partial specific volume of PAMPS (0.575 cm 3 /g) was obtained from density measurements using pycnometry. As a result of increase in thickness (volume) of the membranes, the polymer volume fractions of the PAMPS pore-filling gels were limited to values between 0.01 and 0.06, relatively low values compared to values achieved with other gel-filled membranes based on the same substrate. The Darcy permeability of PAMPS gel-filled membranes exhibits a typical relationship with polymer volume fraction, but the absolute values obtained are much lower than those of other gel-filled membranes previously studied. The lower permeability could be attributed to tightly bound water molecules along polymer chains, which effectively enlarges the hydrodynamic size of polymer chains and narrows the channels for water transport. Using the sphere model based on the Odijk's theory of semidilute polyelectrolyte solutions, the Darcy permeability of PAMPS gel-filled membranes could be calculated with good precision.

Research paper thumbnail of Chemical valves based on poly(4-vinylpyridine)-filled microporous membranes

Journal of Membrane Science, 1999

Microporous membranes containing poly(4-vinylpyridine) anchored within the pores exhibit very lar... more Microporous membranes containing poly(4-vinylpyridine) anchored within the pores exhibit very large chemical valve effects with pressure-driven permeability changing by more than three orders of magnitude as a function of pH. The factors affecting the magnitude of this valve have been examined with a series of well characterized, poly(4-vinylpyridine)-modi®ed, microporous polypropylene membranes. The permeability of these membranes to HCl/H 2 O at different pHs was measured as a function of pore size of the starting base membrane and the amount of poly(4-vinylpyridine) anchored within the pores. An analysis of these results shows that the magnitude of the chemical valve is largely determined by the permeability of the membranes in their open-valve states, i.e., high pH. While the magnitude of the chemical valve effect exhibited by the membranes varied, the pH at which the valve closed was in each case found to be similar and independent of pore size of the starting membrane or amount of poly(4-vinylpyridine) anchored within the pores. The permeability of the membranes at low pH (when the anchored poly(4-vinylpyridine) is ionized) was examined using two existing models of hydrodynamic permeability, namely, the pressure-driven¯ow through a right-cylinder pore partly obscured by a graft layer of a hydrodynamic thickness L H (brush model) and the hydrodynamic¯ow through supported hydrogels (pore-®lled model). The theory of polyelectrolytes in the semi-dilute region was used to estimate the chain parameters of the incorporated polyelectrolyte. The results obtained show that the applicability of each model depends on the pore size of the substrate membranes and the molecular weight of the polyelectrolyte. #