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Biomedical subjects

M Petric

Publications and source records attributed to M Petric.

At least 19 recordsLinked to original sources
PubMed2006

Design of a single tube RT-PCR assay for the diagnosis of human infection with highly pathogenic influenza A(H5) viruses.

Concerns about emergence of a pandemic strain of influenza have been increasing. The strains of highly pathogenic influenza A(H5N1) currently circulating are considered among the most plausible candidates for giving rise to a pandemic strain. In this study the design and development of a RT-PCR assay specific for these highly pathogenic influenza A(H5) strains is presented. This is achieved in part by the design of a primer targeting the coding region for the protease cleavage site of the hemagglutinin, and another primer derived from a pan-hemagglutinin RT-PCR assay also presented in this study. It is shown that the HPAI A(H5) specific assay amplifies only the nucleic acids of highly pathogenic A(H5), with a high sensitivity.

Animals↗
PubMed2006

Estimating vaccine effectiveness against laboratory-confirmed influenza using a sentinel physician network: results from the 2005-2006 season of dual A and B vaccine mismatch in Canada.

INTRODUCTION: We report a case-control design using a sentinel physician network to estimate vaccine effectiveness (VE) against laboratory-confirmed, medically attended influenza (LC-MAI) and provide results for the 2005-2006 season of dual A and B vaccine mismatch in Canada. METHODS: Participants were patients >or=5 years of age presenting with influenza-like illness (ILI) to a sentinel physician in British Columbia, Canada between November 1, 2005 and April 30, 2006. Cases were participants in whom influenza was identified; controls tested negative for influenza A and B by PCR, R-mix and culture. Isolates were characterized by gene-sequencing and hemagglutination-inhibition (HI) assays. Odds ratios (OR) for LC-MAI in vaccinated versus non-vaccinated persons were derived with adjustment for age and chronic conditions. VE was estimated as [1-OR (vaccinated/unvaccinated)]. RESULTS: The sample included 442 patient visits: median age was 26 years, 10% were >or=65 years, 15% had a chronic condition and 22% received the 2005-2006 trivalent inactivated influenza vaccine >or=2 weeks before ILI onset. Two hundred and six participants were positive for influenza; 107 (52%) had influenza A/H3N2 and 99 (48%) had influenza B/Victoria lineage. Gene sequencing identified mutations away from the vaccine strain at key antigenic binding sites of the hemagglutinin (HA) protein of H3N2 isolates; the neuraminidase (NA) protein was conserved. Based on HI assays, three-quarters of influenza A and all B isolates were mismatched to the 2005-2006 vaccine. Point estimates for VE against LC-MAI were in the range of 50 to 70% for both types of influenza. CONCLUSION: 2005-2006 was the third consecutive season of vaccine mismatch based on varying HA for the A/H3N2 component and the third also for the B component since 2001. Vaccine mismatch resulted in diminished VE but substantial cross-protection. More timely detection of drift variants through gene sequencing of isolates facilitates interpretation of VE results. Since it may be more antigenically conserved, the vaccine content and contribution of NA to overall VE should be further evaluated for both A and B components. Infrastructure for real-time epidemiologic assessment of vaccine performance is important annually and in preparation for a pandemic.

Adolescent↗
PubMed2005

Diagnostic accuracy of self collected vaginal specimens for human papillomavirus compared to clinician collected human papillomavirus specimens: a meta-analysis.

BACKGROUND/OBJECTIVES: Providing summary recommendations regarding self collection of vaginal specimens for human papillomavirus (HPV) testing is difficult owing to the wide range of published estimates for the diagnostic accuracy of this approach. To determine summary estimates from analyses of reported findings of the sensitivity, specificity and summary receiver operating characteristic curves (SROC) for self collected vaginal specimens for HPV testing compared to the reference standard, clinician collected HPV specimens. METHODS: Standard search criteria for a diagnostic systematic review were employed. Eligible studies were combined using a random effects model and summary ROC curves were derived for overall and for specific subgroups. RESULTS: Summary measures were determined from 12 studies. Six studies where patients used Dacron or cotton swabs or cytobrushes to obtain samples were pooled and had an overall sensitivity of 0.74 (95% CI 0.61 to 0.84) and specificity of 0.88 (95% CI 0.83 to 0.92), with diagnostic odds ratio of 22.3 and an area under the curve of 0.91. Self specimens using Dacron or cotton swabs or cytobrushes collected by women enrolled at referral clinics had an overall sensitivity of 0.81 (95% CI 0.65 to 0.91) and specificity of 0.90 (95% CI 0.80 to 0.95). Sensitivity and specificity of tampons ranged from 0.67-0.94 and 0.80-0.85 respectively. CONCLUSIONS: Our findings indicate that the combined sensitivity for HPV-DNA is more than 70% when patients use Dacron swabs, cotton swabs, or cytobrushes to obtain their own vaginal specimens for HPV-DNA evaluation. Self collected HPV-DNA swabs may be an appropriate alternative for low resource settings or in patients reluctant to undergo pelvic examinations.

Area Under Curve↗
PubMed2003

Mapping ganciclovir resistance in the human herpesvirus-6 U69 protein kinase.

Human herpesvirus-6 (HHV-6) is a growing concern in immunocompromised individuals, such as in the transplant setting. Alone, or in concert with human cytomegalovirus (HCMV), infections with HHV-6 are often severe enough to require antiviral therapy, generally in the form of ganciclovir (GCV). GCV resistance in HCMV is well documented, both clinically and in the laboratory, and has been shown to result from mutations in the UL97 protein kinase and/or UL54 DNA polymerase. GCV resistance in HHV-6 has been documented. However, to date, it has only been investigated to a limited extent. The baculovirus system has previously been shown to be useful in studying GCV resistance with respect to herpesvirus protein kinase mutations. Using the baculovirus system, we created recombinant baculoviruses expressing either a wild-type HHV-6 U69 protein kinase or a mutated form containing homologous mutations to those documented in the UL97 protein kinase of GCV resistant HCMV isolates. The recombinant baculoviruses were used to infect Sf-9 cells and cultured in the presence of GCV to determine the effect of the HHV-6 U69 protein kinase mutations on GCV susceptibility. Mutations in the HHV-6 U69 protein kinase, homologous to those in the HCMV UL97 protein kinase documented to cause GCV resistance, result in GCV resistance in the recombinant baculoviruses.

Animals↗
PubMed2002

Histological improvement with lamivudine therapy for de novo hepatitis B occurring in an anti-HBs-positive child after bone marrow transplantation.

We describe a 14-year-old bone marrow transplant recipient who was anti-HBs-positive before the procedure and afterwards developed acute infection with hepatitis B virus (HBV). Liver biopsies taken while symptomatic showed portal fibrosis progressing to cirrhosis. The patient responded to lamivudine treatment with HBeAg seroconversion and significant regression of fibrosis. Although the source and timing of HBV exposure remain unclear, the potential for severe hepatitis B infection following bone marrow transplant warrants caution. This case demonstrates that a symptomatic HBV infection can occur in an immunocompromised patient who had originally been anti-HBs-positive.

Adolescent↗
PubMed2002

Rapid painless diagnosis of viral respiratory infection.

The concordance of nasal compared with nasopharyngeal swabs was assessed for the diagnosis of respiratory viral infections, and the degree of discomfort associated with each procedure was compared. The use of nasal swabs was shown to be as accurate but significantly less painful than nasopharyngeal swabs for virus diagnosis.

Adolescent↗
PubMed2002

Cross-protection against challenge by intravenous Escherichia coli verocytotoxin 1 (VT1) in rabbits immunized with VT2 toxoid.

Rabbits challenged intravenously with Escherichia coli verocytotoxin (VT1, Shiga toxin 1, Stx1) die after developing diarrhea and paralysis, and this outcome can be prevented by pre-immunization with VT1 toxoid. In nonimmune rabbits, intravenously administered 125I-VT1 binds to the central nervous system and gastrointestinal tract, whereas in immunized animals, these organs are spared and the toxin localizes in the liver and spleen. In rabbits immunized with either VT1 or VT2 toxoids, both the homologous or heterologous toxins are prevented from binding to target organs. This has lead to the advancement of a hypothesis that cross-protection in vivo can be induced to both toxins by immunization with a toxoid even though these toxins do not exhibit cross-neutralization in vitro. It was shown that rabbits immunized with VT2 were fully protected from the intravenous administration of 10 LD50 and 50 LD50 of VT1, and this correlated directly with the protection from binding of this toxin to target organs. These findings have important implications on the design of the vaccination strategies to prevent human VT-mediated diseases and also validate the concept of testing for immunity to VT by monitoring the inhibition of binding of the 125I-VT to target organs in preference to performing LD50 assays.

Animals↗
PubMed2002

Transhiatal surgical resection for adenocarcinoma of the cardia.

Aim of this study is to define feasibility and effectiveness of the transhiatal esophagogastric resection in cardia adenocarcinoma. From 1981 to 2001, we submitted to surgery 85 patients affected by cardia adenocarcinoma. Since 1994, 34 patients, in consideration of clinical, anatomosurgical (Siewert II-III) and pathologic (T1-3, cN mediastinal negative) findings, underwent transhiatal esophagogastric resection according to Pinotti's technique. This consisted in the midline opening of the central tendon of the diaphragm, ligature and section of the left inferior phrenic vessels, exposure and anterior retraction of the pericardium. The approach allowed in all cases a satisfactory esophageal mobilization and a good dissection of the inferior mediastinal structures avoiding thoracotomy. Postoperative complications were observed in 8 patients (24%). In 4 cases the complications were medical (11.8%) and in 4 cases surgical (11.8%). Death occurred in 4 cases (11.8%): in 3 patients (8.8%) for local complications (2 anastomotic leaks and 1 hemorrage) and in 1 (2.9%) for cardiac failure. The 26 non complicated cases had an uneventful postoperative course and were discharged 12 days after surgery. Middle and long term results were evaluated in terms of locoregional recurrence rate and actuarial survival. At 1 and 2 years locoregional recurrence occurred in 8.8% and 11.8% of cases respectively. Five-year overall survival was 22.5%. In selected cases (Siewert type II-III, T1-3 tumors with clinically negative mediastinal lymphnodes) the procedure in study appears technically feasible, it provides a satisfactory volume of esophageal exeresis and an adequate extension of mediastinal lymphadenectomy, representing a safe and effective alternative to thoracotomy in cardia cancer surgery.

Adenocarcinoma↗
PubMed2002

Sentinel node in gastric cancer surgery.

Sentinel Node (SN) biopsy studies have been recently applied to gastric cancer. In this series, 40 selected patients operated for gastric adenocarcinoma located in the lesser curvature and/or anterior wall of the body and antrum, underwent an intraoperative dye lymphography. The lymphatic ducts and nodes were visualized and a SN was evidenced in all cases. This was removed and a frozen section examined. In all cases a radical D2-3 gastrectomy was performed and histology, molecular biology, RT-PCR research of micrometastases (CEA-mRNA), were determined on the specimens. Correlations between T and histological status of SN and regional nodes were done. In 16 cases the SN was negative and all the resected regional nodes were negative too. In 15 cases the SN node was positive and other nodes in other stations were found to be positive as well. In 2 cases the SN was negative but other nodes, in the same stations and in others, were positive (false negative = 5%). In 7 cases the SN was the only node in which metastases occurred, 3 demonstrated by conventional histology and 4 detected by RT-PCR. In these 7 cases the SN was the only involved node out of all resected nodes, thus demonstrating to be the real first node along the lymphatic routes from the tumour. This experience seems to confirm the existence of a Sentinel Node and that each gastric adenocarcinoma has its own lymphatic basin in which metastasis can occur. Although a prudent attitude towards the indications resulting from these observations is required, in selected cases a controlled and tailored lymphoadenectomy could be adopted.

Humans↗
PubMed2001

The role of infections in primary hemophagocytic lymphohistiocytosis: a case series and review of the literature.

There is a paucity of literature addressing infection-related morbidity and mortality in children with primary hemophagocytic lymphohistiocytosis (HLH), a rare condition characterized by abnormal proliferation of macrophages, hypercytokinemia, and T cell immunosuppression. Therefore, a retrospective chart review was done of patients diagnosed with primary HLH over a 15-year period. Significant infections present at diagnosis, during the course of illness, and just prior to death or at autopsy were noted. Of the 18 children identified with primary HLH, an infectious agent was documented at the initial presentation of HLH in 5. Significant infections occurred during therapy in 10 (56%) of 18. Of the 12 fatal cases, invasive infection was the cause of death in 8 children, and 6 of these deaths were directly attributable to invasive fungal infection. Significant infections were common during therapy in children with primary HLH, and fungal infections were an important cause of mortality in this group.

Bacterial Infections↗
PubMed2001

Utility of semiquantitative polymerase chain reaction for Epstein-Barr virus to measure virus load in pediatric organ transplant recipients with and without posttransplant lymphoproliferative disease.

We examined the utility of Epstein-Barr virus (EBV) load as a test for the presence of posttransplant lymphoproliferative disease (PTLD). A semiquantitative (SQ) EBV polymerase chain reaction (PCR) on peripheral blood mononuclear cells (PBMC) was used to determine virus load. We compared the values from pediatric patients, both with and without PTLD, with those from healthy pediatric and adult subjects. The virus loads for asymptomatic healthy subjects had a range of 0-1 log10 cells/10(6) PBMCs. Among transplant recipients (n=135), the mean virus load (+/- standard deviation) at the time of diagnosis of PTLD was 3.1+/-1.2 log(10) cells/10(6) PBMCs versus a baseline value of 1.3+/-1.4 log(10) cells/10(6) PBMCs in children without PTLD (P<.0001). A cutoff of > or =3 log10 cells/10(6) peripheral blood leukocytes resulted in the following values for use of virus load as a test for PTLD: sensitivity, 69%; specificity, 76%; positive predictive value, 28%; and negative predictive value, 95%. We conclude that determination of EBV load by use of SQ PCR is more useful in ruling out than in indicating the presence of PTLD.

Adult↗
PubMed2001

Acute childhood encephalitis and Mycoplasma pneumoniae.

In a prospective 5-year study of children with acute encephalitis, evidence of Mycoplasma pneumoniae infection was demonstrated in 50 (31%) of 159 children. In 11 (6.9%) of these patients, M. pneumoniae was determined to be the probable cause of encephalitis on the basis of its detection in cerebrospinal fluid (CSF) by polymerase chain reaction (PCR) or by positive results of serologic tests for M. pneumoniae and detection of the organism in the throat by PCR. CSF PCR positivity correlated with a shorter prodromal illness (P=.015) and lack of respiratory symptoms (P=.06). Long-term neurologic sequelae occurred in 64% of probable cases. Thirty children (18.9%) who were seropositive for M. pneumoniae but did not have the organism detected by culture or PCR had convincing evidence implicating other organisms as the cause of encephalitis, suggesting that current serologic assays for M. pneumoniae are not sufficiently specific to establish a diagnosis of M. pneumoniae encephalitis.

Acute Disease↗
PubMed2001

The utility of plasma polymerase chain reaction for human herpes virus-6 among pediatric bone marrow transplant recipients: results of a pilot study.

We evaluated the utility of plasma polymerase chain reaction (PCR) for surveillance of human herpes virus 6 (HHV-6) infection among pediatric bone marrow transplant (BMT) recipients. We used a prospective, non-interventional design involving a study group and controls. BMT recipients and healthy controls were evaluated. BMT subjects had HHV-6 PCR done biweekly for 12 weeks post transplantation, while a single PCR test was done on controls. For the PCR assay, EDTA blood was collected and DNA extracted from whole blood and cell-free plasma using standard procedures. The PCR was first performed on DNA from whole blood and if a positive result was obtained, the test was repeated on the DNA from the plasma. Thirty BMT recipients (13 autologous and 17 allogeneic) were enrolled, on whom a total of 156 PCR tests were performed, while six tests were done on six healthy controls. The median age of BMT subjects was 6.2 years (range 0.5-17.5 years). The median age of the control subjects was 6.6 years (range 2-10 years). Among asymptomatic BMT patients who had PCR surveillance, the positivity rate was 3.3% (1/30) on whole blood and 0% (0/30) on plasma. None of the six healthy subjects had a positive PCR test on whole blood. During the period of the surveillance study, 14 patients had diagnostic evaluations for HHV-6 disease because of clinical symptoms. Two of these patients were diagnosed with disease associated with HHV-6 (graft failure and encephalitis) and had positive PCR tests on whole blood and plasma and whole blood and cerebrospinal fluid, respectively. We conclude that despite the fact that HHV-6 seropositivity rates are high among children, the frequency of HHV-6 plasma PCR positivity is low in pediatric BMT subjects who are asymptomatic for HHV-6 disease. Given that a positive test on plasma is consistent with active infection, this increases the utility of the PCR test as a diagnostic aid in evaluating syndromes presumed to be due to HHV-6 in pediatric bone marrow transplant recipients.

Adolescent↗