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Biomedical subjects

M Petric

Publications and source records attributed to M Petric.

At least 73 records · Page 4Linked to original sources
PubMed1995

Acute cytomegalovirus infection in a child with Ménétrier's disease.

The cause of Ménétrier's disease is unknown, although allergic, autoimmune, and infectious, particularly viral, causes have been postulated. This case report describes a 3-year-old child with Ménétrier's disease in whom evidence of acute cytomegalovirus (CMV) infection was found. To our knowledge, this is the first case with evidence of acute infection, indicated by the presence of CMV-specific immunoglobulin M antibody in the acute serum as well as a seroconversion to CMV. CMV was also found in a gastric mucosal biopsy specimen using monoclonal antibodies to the early antigen of CMV.

Acute Disease↗
PubMed1994

Modern therapeutic approaches to postmastectomy brachial lymphedema.

Over the past 10 years we have treated 36 patients affected by upper limb lymphedema, associated with mastectomy and axillary dissection, by either macrosurgical exeresis or microsurgical techniques. All cases had been unresponsive to prior drug or physical therapy (pressure and thermal therapy). Preoperative upper limb status was thoroughly examined by evaluating volume measurements, dynamic lymphoscintigraphy, venous Doppler fluximetry, ultrasonography, and nuclear magnetic resonance. Selected tests were repeated during follow-up to obtain more statistically significant results. Twenty-five of the 36 patients in our series presented a grade II lymphedema and underwent Degni-Cordeiro's microsurgical indirect lymphatico-venous shunt (L.V.S.) surgery. Fifteen of the 25 also received fasciotomies performed along the posterior aspect of the forearm. Three of the 36 patients presented grade II lymphedema and upper limb venous hypertension. These were treated with multiple fasciotomies alone. The remaining eight patients presented grade III lymphedemas. Seven underwent Kondoleon's partial superficial lymphangectomy, and one was treated with Servelle's total superficial lymphangectomy. Of the 36 patients who underwent surgery, only 27 were checked at 6 months; 22 were seen at 18 months. The remaining patients were followed up for too short of a period of time to be considered. Results were arranged into three groups. Classification criteria were: reduction of upper limb dimensions and the presence of the pre-existing symptoms (episodes of lymphangitis, pain, functional deficits. Results were considered good (class 3), fair (class 2), or poor (class 1). A positive clinical picture (class 2-3) was seen in 74% (20/27) at 6 months and in 59% (13/22) at 18 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Arm↗
PubMed1994

Electrophoretic migration of adenovirus hexon under non-denaturing conditions.

While SDS-PAGE/immunoblotting is a valuable approach for the characterization of monoclonal antibodies, the denaturing conditions involved can compromise the recognition of conformational epitopes. This report demonstrates that a group specific epitope on adenovirus hexon can be recognized by immunoblotting following SDS-PAGE provided that samples are not boiled prior to electrophoresis. Under these conditions, multiple bands corresponding to native forms of hexon were detected above the position of the denatured hexon monomer. Among representative serotypes of subgroups A, B and F, two predominant bands, corresponding to hexon trimers and 'group of nine' hexons (GONs), were routinely observed. In contrast, higher order structures, in addition to trimers and GONs, were characteristic of subgroup C adenoviruses. These serotypic differences in stability of hexon structures may reflect differences in protein-protein interactions within the corresponding virions.

Adenoviruses, Human↗
PubMed1994

Evidence that verotoxins (Shiga-like toxins) from Escherichia coli bind to P blood group antigens of human erythrocytes in vitro.

The interaction of verotoxins (VTs) with human erythrocytes (RBCs) in vitro was investigated, with particular reference to the role of P blood group glycolipids that are structurally related to the known VT receptors. RBC binding of purified VT1, VT2, VT2c, and VT2e was detected by direct and indirect immunofluorescence. Glycolipids were extracted from defined RBCs, separated by thin-layer chromatography, and assessed for VT binding in an overlay assay by adding toxin and specific antibodies. All VTs bound to P1 phenotype (Pk, P, and P1 antigens) and P2 phenotype (Pk and P antigens) RBCs but not to p phenotype (lacking the Pk, P, and P1 antigens) RBCs. Binding of VT1 and VT2 was approximately 10-fold greater to P1 and the rare Pk2 (Pk antigen but no P1 or P antigen) phenotype cells than to P2 phenotype RBCs, whereas VT2e bound equally well to P1 and P2 phenotype cells. The VT1 and VT2 immunofluorescence results correlated with the detection of P1 and/or increased amounts of Pk (globotriaosylceramide) antigen; VT2e immunofluorescence correlated with the detection of P (globotetraosylceramide) antigen. The Pk band pattern and VT binding observed in the thin-layer chromatogram of human P1 and P phenotype RBC extracts varied from that of human kidney and Pk1 phenotype (Pk and P1 antigens) RBCs. We conclude that each VT binds to human RBCs in vitro by utilizing specific P blood group glycolipids as receptors. On P1 and P phenotype RBCs, the accessibility of the Pk antigen for VTs appeared to be restricted. The occurrence of VT-RBC binding in natural VT-producing Escherichia coli disease and its relevance for the pathophysiology of hemolytic uremic syndrome remain to be established.

Bacterial Toxins↗
PubMed1994

Enzyme-linked immunosorbent assay for detection of immunoglobulin G antibodies to Escherichia coli Vero cytotoxin 1.

The frequency of Vero cytotoxin 1 (VT1)-neutralizing antibody (NAb) in serum specimens from 790 age-stratified (0 to 70 years) control individuals from Toronto was 61 of 790 (7.7%), with a peak of 19% in the 20- to 30-year-old age group and a second peak of 16.7% in the 60- to 70-year-old age group. A total of 568 serum specimens, including 538 from the 790 Toronto control subjects, 21 from patients from three outbreaks of VT-producing Escherichia coli (VTEC) infection, and 9 known VT1-NAb-positive serum specimens from patients with hemolytic-uremic syndrome (HUS), were then tested for the presence of anti-VT1 immunoglobulin G (IgG) by an enzyme-linked immunosorbent assay (ELISA). The mean ELISA values of 522 VT1-NAb-negative serum specimens and 46 VT1-NAb-positive serum specimens were 0.09 +/- 0.06 (range, 0 to 0.56) and 0.78 +/- 0.66 (range, 0.16 to 2.91), respectively (P < 0.001; Student's t test). With a breakpoint of 0.21 (mean ELISA value of the VT1-NAb-negative sera + 2 standard deviations), the sensitivity, specificity, positive predictive value, and negative predictive value of the VT1 IgG ELISA compared with those of the VT1-NAb assay were, respectively, 95.7, 98.7, 86.3, and 99.6%. There were nine discrepant serum specimens, of which seven were anti-VT1 IgG positive and VT1-NAb negative and two were anti-VT1 IgG negative and VT1-NAb positive. The ELISA was also used for testing 238 control serum specimens from The Netherlands, Japan, and India and acute- and convalescent-phase serum specimens from 42 Toronto patients with HUS. The frequencies of anti-VT1 IgG (with VT1-NAb frequencies in parantheses) in control sera from the Netherlands, Japan, and India were 6% (3%), 1.1% (0%), and 12% (10%), respectively, with no age clustering. The frequencies of anti-VT1 IgG seropositivity in HUS patients were 5 of 14 (35.7%) in patients with unknown toxin exposure, 2 of 22 (9.1%) in individuals with known exposure to VT1 plus VT2 or VT1 alone, and 0 of 6 (0%) in patients exposed to only VT2. Development of serum anti-VT1 IgG response appears to be the exception rather than the rule in sporadic HUS patients infected with VTEC expressing VT1. However, in two family outbreaks associated with VTEC strains expressing VT1 alone and VT1 plus VT2, respectively, the presence of anti-VT1 IgG in virtually all exposed individuals who remained symptom free suggests that the presence of antibody was associated with protection.

Adolescent↗
PubMed1994

Identification of minireovirus as a Norwalk-like virus in pediatric patients with gastroenteritis.

In 1977, 30- to 32-nm virus-like particles, named minireovirus because of their unique morphologic appearance, were detected by electron microscopy in the stools of infants and young children with gastroenteritis. Sequence analysis of approximately 2,800 consecutive bases derived from overlapping PCR clones of a recent minireovirus clinical isolate showed 52% nucleotide sequence identity with the Norwalk virus sequence and, in addition, demonstrated that the genomic organizations of these two viruses were similar. Our data show that minireovirus is a Norwalk-like virus and should now also be included in the Caliciviridae family.

Amino Acid Sequence↗
PubMed1994

Influenza A outbreak in a nursing home: the value of early diagnosis and the use of amantadine hydrochloride.

An outbreak of respiratory tract infection due to influenza A virus occurred in February 1994 among residents of an 88-bed long term care facility in Toronto, Ontario. Eighteen confirmed and four probable cases of influenza were identified for an attack rate of 25%. Seventy-one per cent of the residents were known to have been immunized with trivalent influenza vaccine, but vaccine efficacy was determined to be only 32%. Influenza A viral antigen was rapidly detected by immunofluorescence microscopy of nasopharyngeal swabs, and amantadine hydrochloride was started in 76 residents within 48 h of recognizing the outbreak. Only two of the residents (3%) at risk became ill more than 48 h after amantadine was started. Amantadine was discontinued in four residents (5%) because of adverse effects (agitation, confusion, unsteady gait). In conclusion, rapid identification of the outbreak and prompt administration of amantadine hydrochloride prophylactically appears to be safe and effective in preventing further spread of influenza A.

Amantadine↗
PubMed1993

Enzyme-linked immunosorbent assay reactivity of torovirus-like particles in fecal specimens from humans with diarrhea.

Toroviruses are recognized enteric pathogens of cattle and horses; in humans, similar pleomorphic particles have been described, but doubt has been raised concerning their identity as viruses. We screened fecal samples from humans with diarrhea for the presence of torovirus-like particles (TVLPs) by electron microscopy and subsequently used an enzyme-linked immunosorbent assay (ELISA) with bovine torovirus reference reagents to test for the presence of torovirus antigens. To add another selection criterion to this heterologous ELISA, we enriched the TVLPs from the stool specimens by using sucrose density gradients before testing. The results of ELISA and EM correlated significantly, the ELISA having a sensitivity of 68% and a specificity of 86% (chi-square, P < 0.0001). In the gradient, peaks of ELISA reactivity were found at a buoyant density of 1.16 g/ml and were parallel to those found when using bovine torovirus. Furthermore, in 50% of the ELISA-positive gradients, a hemagglutinin for human group O erythrocytes comigrated with the peaks of ELISA reactivity. We were unable to isolate human TVLPs in human colonic tumor or rectal tumor cells. We cloned and sequenced amplification products obtained by low-stringency polymerase chain reaction amplification using consensus primers mapping to the 3' end of the genome of animal toroviruses, but found no significant homologies with animals torovirus sequences. Rabbits were inoculated with material from the gradient peak fractions of human stool specimens, and their sera were assayed for immunologic comparison with bovine torovirus as a reference. A two-way antigenic cross-reactivity was seen between human TVLP and bovine torovirus reagents when tested by ELISA. The rabbit antisera to human TVLP detected a higher number of electron microscopy-positive stool specimens than did the rabbit antisera to bovine torovirus. The application of these assays and reagents should help to elucidate the roles of TVLPs and toroviruses in diarrheal disease in humans.

Animals↗
PubMed1992

Terminal sequence conservation among the genomic segments of a group B rotavirus (IDIR strain).

Terminal nucleic acid sequences were determined for all 11 segments of the IDIR strain of group B rotavirus. Consensus sequences were defined at both ends of the (+) RNA strands as 5' GGN(A/U)NA(A/U)(A/U)(A/U)---and---(A/U)NA(A/G)N(A/C)(C/A)CC3 '. The 5' and 3' terminal sequences of the (+) strand IDIR RNA were not complementary to one another. The IDIR terminal sequences and those of group A rotaviruses (GAR) were similar in that each of the (+) strands began with "GG" and ended with "CC." Otherwise, the IDIR terminal sequences did not match the consensus sequences that have been reported for the ends of the GAR genomic segments.

Base Sequence↗
PubMed1992

Molecular cloning, sequence analysis, in vitro expression, and immunoprecipitation of the major inner capsid protein of the IDIR strain of group B rotavirus (GBR).

The sixth genomic segment of the infectious diarrhea of infant rats (IDIR) strain of group B rotavirus (GBR) was cloned from double-stranded RNA purified from infected rat feces. Sequence comparison with group A rotaviruses (GAR) and the human ADRV strain of GBR indicated that IDIR gene 6 encoded the major inner capsid protein. The nucleic acid sequences of the two GBR genes were 72.9% conserved, and 83.4% of the amino acids were identical. Sequence substitutions between IDIR and ADRV were more numerous than reported for heterologous GAR strains, indicating that the two GBR strains may have diverged from one another over a longer period of time. Despite the sequence heterogeneity exhibited by the major inner capsid proteins of ADRV and IDIR, hydrophilicity plots of the two gene products were nearly indistinguishable. The GBR hydrophilicity plots displayed little similarity with those of rotavirus groups A or C, indicating substantial differences in the structures of those major inner capsid proteins. In vitro transcription and translation of IDIR gene 6 yielded a polypeptide product consistent in size with that predicted from the deduced amino acid sequence and the virion major inner capsid protein. The IDIR 6 polypeptide was immunoprecipitated by antisera directed against IDIR as well as antisera directed against ADRV and a heterologous bovine strain of GBR. No immunoprecipitation was observed with control sera or antisera directed against GAR. These results confirmed that group-specific epitopes were displayed by the major inner capsid protein encoded by IDIR gene 6. Reactivity with heterologous GBR antisera also indicated that the IDIR gene 6 product may prove useful as a standard reagent in immunoassays for the detection of GBR.

Amino Acid Sequence↗
PubMed1992

Baculovirus expression of pestivirus non-structural proteins.

Bovine viral diarrhoea virus (BVDV) belongs to the pestivirus group, a genus within the Flaviviridae family. It possesses a positive-sense ssRNA genome with a single large open reading frame (ORF) encoding about 4000 amino acids. Here we report the continuation of our studies of pestivirus protein biogenesis, involving expression from the viral non-structural protein-encoding region. The 3'-terminal 60% of the BVDV ORF was cloned into a plasmid transfer vector which was then used to construct a recombinant baculovirus. Infection of Spodoptera frugiperda Sf9 cells with this recombinant virus resulted in the production of the expected mature viral proteins. Polyprotein processing by the BVDV p80 proteinase appeared to be nearly identical to that observed in authentic BVDV-infected bovine cells, and as previously shown to occur when expression of the same region was studied in a mammalian cell transient expression system. However, one viral proteolytic cleavage did not occur in the baculovirus-infected insect cells; the viral p80 proteinase failed to act at its own N terminus. This recombinant baculovirus/insect cell expression system provides an abundant source of BVDV non-structural proteins. Therefore we explored the utility of the proteins produced in this system for the detection of anti-BVDV antibodies in bovine sera. In preliminary experiments using these antigens in an ELISA we found a positive correlation between the presence of ELISA-reactive antibody and virus-neutralizing activity.

Animals↗
PubMed1992

Experimental verocytotoxemia in rabbits.

The clinicopathologic effects of intravenously administered purified verocytotoxin 1 (VT1; Shiga-like toxin 1) in 2-kg male rabbits was studied. The 50% lethal dose was 0.2 micrograms of protein per kg of body weight (2 x 10(4) 50% cytotoxic doses per kg). The clinical features included nonbloody diarrhea and a progressive flaccid paresis, usually culminating in death. The histopathology was characterized by edema and hemorrhage in the mucosa and submucosa of the cecum and edema, hemorrhage, and neuronal necrosis in the brain and gray matter of the spinal cord. Thrombotic microangiopathy, the characteristic histopathologic renal lesion in the hemolytic-uremic syndrome, was also found to be the underlying lesion in verocytotoxemic rabbits. To determine the specific distribution of VT1 in rabbit tissues, purified 125I-labelled VT1 was administered intravenously to 20 rabbits (both immunologically naive and VT1-immune rabbits). The highest specific uptake of 125I-VT1 was in the spinal cord, brain, cecum, colon, and small bowel in unimmunized animals but in the liver, spleen, and lungs in immune animals. Immunofluorescent staining of cecal and spinal cord tissues after intravenous administration of VT1 showed evidence of specific vascular endothelial cell binding of the toxin. The striking correlation of the central nervous system and gastrointestinal localization of 125I-VT1 with the sites of known histopathology is consistent with direct toxin-mediated injury to these tissues, initiated by the specific binding of VT1 to the vascular endothelium. We conclude that the vascular damage induced by VT1 in affected rabbit tissues is similar to that seen in the kidneys and other tissues in patients with verocytotoxin-producing Escherichia coli-associated hemolytic-uremic syndrome. This suggests that although the rabbit model fails to replicate human hemolytic-uremic syndrome, it is useful for studying the pathogenesis of the vascular lesions in verocytotoxin-producing E. coli-associated diseases.

Animals↗
PubMed1991

Hepatitis C infection in children with hemophilia A and B.

Antibodies to hepatitis C virus (anti-HCV) were quantitated in stored sera from selected groups of hemophilic children (less than or equal to 18 years of age). During the period 1987 to 1989, seropositivity rates were as follows: untransfused hemophiliacs 0% (0 of 11 cases), hemophiliacs treated exclusively with vapor-heated factor VIII or IX concentrates 0% (0 of 9 cases), hemophiliacs treated only with cryoprecipitate or single donor blood products 0% (0 of 9 cases), and hemophiliacs regularly treated with unheated or dry heat-treated factor VIII or IX concentrates 95% (21 of 22 cases). Corresponding alanine aminotransferase (ALT) results were similar: values were always below the upper limit of laboratory normal (40 U/L) in untransfused hemophiliacs, hemophiliacs treated with vapor-heated factor concentrates, or those who received only cryoprecipitate or single donor blood products. By contrast ALT values were greater than 40 U/L in 82% (18 of 22 cases) of hemophilic children regularly infused with unheated or dry heat-treated factor concentrates. Three conclusions are drawn from this data: (1) HCV is a major cause of chronic hepatitis in multitransfused hemophilic children, (2) unheated and dry heat-treated clotting factor concentrates carry a very high risk of transmitting HCV infection, and (3) clotting factor concentrates inactivated by vapor heating carry a very low and perhaps zero risk of transmitting HCV infection. These findings are of therapeutic significance for previously untransfused hemophiliacs susceptible to HCV infection.

Alanine Transaminase↗
PubMed1991

Syncytial giant-cell hepatitis. Sporadic hepatitis with distinctive pathological features, a severe clinical course, and paramyxoviral features.

BACKGROUND AND METHODS: We describe a new form of hepatitis, occurring in 10 patients over a period of six years, characterized clinically by manifestations of severe hepatitis, histologically by large syncytial giant hepatocytes, and ultrastructurally by intracytoplasmic structures consistent with paramyxoviral nucleocapsids. RESULTS: The patients ranged in age from 5 months to 41 years. The tentative clinical diagnosis before biopsy was non-A, non-B hepatitis in five patients and autoimmune chronic active hepatitis in the others. Five patients underwent liver transplantation; the others died. The diagnosis of syncytial giant-cell hepatitis was established pathologically. The liver cords were replaced in all 10 patients by syncytial giant cells with up to 30 nuclei. In 8 of the 10 the cytoplasm contained pleomorphic particles of 150 to 250 microns, filamentous strands, and particles of 14 to 17 nm with peripherally disposed spikes resembling paramyxoviral nucleocapsids. Structures resembling degenerated forms were found in the other two patients. One of two chimpanzees injected with a liver homogenate from the index patient had an increase in the titer of paramyxoviral antibodies, probably an anamnestic reaction to previous paramyxoviral infection, suggesting that a paramyxoviral antigen but not viable virus was present in the liver homogenate. CONCLUSIONS: Although further virologic studies will be required for precise classification, we believe that paramyxoviruses should be considered in patients with severe sporadic hepatitis.

Acute Disease↗
PubMed1991

Comparison of group B rotavirus genes 9 and 11.

Group B rotaviruses (GBRs) were recognized recently as causative agents of gastroenteritis. Investigations into the relatedness of various heterologous GBR strains have been hindered by the difficulty of growing these viruses in cell culture. Viral RNA extracted from experimentally infected rats used to prepare cDNA clones. From these, the nucleotide sequences of genes 9 and 11 of the IDIR strain of GBR were determined and compared with the corresponding sequences of the human ADRV strain of GBR. IDIR gene 11 is 643 bp in length with a single open reading frame (ORF) encoding 174 amino acids; IDIR gene 9 is 804 bp in length with a single ORF encoding 246 amino acids. Comparison of the IDIR sequences with those of ADRV showed that nucleotide sequence similarity was 60.6% and 71.9% for genes 9 and 11, respectively. The deduced amino acid sequence similarity was 51.2% for the gene 9 and 66.5% for the gene 11 product. This sequence diversity indicates that GBRs are more distantly related than strains of group A rotavirus.

Amino Acid Sequence↗
PubMed1990

Cytomegalovirus infections in pediatric liver transplantation.

From 1986 to 1989, 26 consecutive pediatric liver transplant recipients were followed up at The Hospital for Sick Children, Toronto, Canada. The patients were reviewed to assess the incidence of infection with cytomegalovirus, the severity of disease, and the relationship of recipient and donor serostatus to cytomegalovirus disease. Overall, the incidence of infection was 54% (14/26). Over 90% of patients who were seropositive or whose donors were seropositive developed evidence of cytomegalovirus infection after transplantation. Forty-three percent (6/14) of those with cytomegalovirus infections developed severe, fatal cytomegalovirus disease, despite treatment with immunoglobulins and ganciclovir (Syntex Laboratories Inc, Palo Alto, Calif) or foscarnet sodium (Astra, Pharmaceutical Products Inc, Westborough, Mass). Of all posttransplant deaths, two thirds were associated with severe cytomegalovirus infection. Cytomegalovirus-related deaths occurred in three of four seronegative patients with seropositive donors and three of six seropositive patients with seropositive donors. Therefore, a seropositive donor appeared to be a major risk factor for severe cytomegalovirus disease.

Adolescent↗
PubMed1990

Nebulized albuterol in acute bronchiolitis.

In a double-blind, placebo-controlled trial, 40 infants between 6 weeks and 24 months of age who had a first episode of wheezing and other signs and symptoms of bronchiolitis were randomly assigned to receive either nebulized albuterol (0.15 mg/kg/dose) or placebo (saline solution) for two administrations 1 hour apart. The albuterol therapy resulted in a significantly greater improvement in the accessory muscle score (decreases 0.70 vs decreases 0.30; p = 0.03), oxygen saturation (increases 0.71% vs decreases 0.47%; p = 0.01) after one dose, and in the accessory muscle score (decreases 0.86 vs decreases 0.37; p = 0.02), respiratory rate (decreases 19.6% vs decreases 8.0%; p = 0.016), and oxygen saturation (increases 0.76% vs decreases 0.79%; p = 0.015) after two doses of the drug. The response to therapy was similar in infants younger and those older than 6 months of age. The heart rate rose slightly more in the albuterol group (increases 7.76 from baseline) versus the placebo group (decreases 6.79). There were no other side effects of the treatment. Of the 34 children from whom nasal specimens were obtained by swab for viral identification, 24 had positive test results (21 for respiratory syncytial virus, 1 for parainfluenza, 1 for paramyxovirus, and 1 for influenza A). We conclude that nebulized albuterol constitutes a safe and effective treatment of infants with bronchiolitis.

Acute Disease↗