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Biomedical subjects

M A Gerber

Publications and source records attributed to M A Gerber.

At least 109 records · Page 6Linked to original sources
PubMed1992

Detection of hepatitis C virus RNA sequences by polymerase chain reaction in fixed liver tissue.

Currently, the most reliable method for the diagnosis of hepatitis C virus (HCV) infection is the detection of viral sequences by the reverse transcription double polymerase chain reaction (RT/PCR) in serum or liver samples. We demonstrate here that noncoding region sequences (NT) of HCV were amplifiable by RT/PCR in guanidinium extracts of formalin-fixed (for 6 to 48 h), paraffin-embedded liver sections of patients with chronic hepatitis C. In contrast, core and nonstructural region sequences of HCV were not detectable in fixed tissues by PCR amplification. Boiling of routinely processed tissue sections in water containing Chelex-100, a method for extraction of amplifiable hepatitis B virus DNA, was not successful. The amount of nucleic acid extracts from fixed liver sections needed for amplification of NT region sequences was over 1000 times larger than that of extracts from frozen tissue. This method will be useful for diagnostic and investigative studies of HCV infection.

Aged↗
PubMed1991

Development and application of an in vitro model for screening anti-hepatitis B virus therapeutics.

The development of effective anti-hepatitis B virus agents has been hampered by the lack of reliable in vitro systems for the screening of new therapeutics. In an effort to circumvent this problem, we have developed an in vitro system for screening anti-hepatitis B virus drugs using hepatitis B virus DNA-transfected Hep G2 cells. The cell line designated 2.2.15 produces replicative viral DNA intermediates, mature Dane particles and high levels of viral antigens. Subconfluent 2.2.15 cells were treated with a variety of commonly used anti-hepatitis B virus therapeutics, and their efficacy was determined by analyzing changes in the replicative cellular or extracellular hepatitis B virus DNA content by Southern blotting or slot-blot hybridization. The slot-blot method was sensitive, reproducible and rapid and correlated well with Southern blotting. Analysis of the media for hepatitis B virus DNA was indicative of changes in intracellular, replicative hepatitis B virus DNA, permitting sampling of the media. Therefore 2.2.15 cells may provide a valuable method for identifying and monitoring effective anti-hepatitis B virus therapeutics. Using this system to test various agents, we confirm that 2'-deoxyguanosine strongly inhibited viral replication, whereas others tested were less effective. Correlation with in vivo systems is now needed.

Antiviral Agents↗
PubMed1991

Comparative studies on the detection of hepatitis B virus DNA in frozen and paraffin sections by the polymerase chain reaction.

The polymerase chain reaction (PCR) is an extremely sensitive technique that has been used for detection of DNA sequences in formalin-fixed, paraffin-embedded tissues. In order to verify that hepatitis B virus (HBV) DNA sequences are adequately preserved in routinely processed liver tissues, we performed PCR with five different primer pairs for HBV sequences on DNA extracted by two different methods from paraffin and frozen liver sections. The amount of PCR products obtained with DNA templates extracted by the proteinase K-SDS method from frozen sections was significantly larger than that from paraffin sections. However, boiling of deparaffinized sections in water containing Chelex-100 resulted in ample amounts of PCR products irrespective of the primers used. On Southern blots, the location of the bands of amplified DNA obtained by the different methods was consistent with the predicted size, suggesting that the viral sequences had not been altered by processing. Although freezing of fresh tissue yields quantitatively more HBV DNA, formalin fixation qualitatively preserves the viral DNA sequences adequately for detection by PCR. Therefore, formalin-fixed, paraffin-embedded tissues may be used for the detection of viral DNA sequences by PCR. Application of the described procedure to routinely processed tissues significantly broadens the applicability of this powerful diagnostic and investigative method.

Base Sequence↗
PubMed1991

Immunohistochemical studies of human immunodeficiency virus-1 in liver tissues of patients with AIDS.

A wide spectrum of hepatic lesions has been reported in AIDS, but it is not known whether the changes are related to the presence of human immunodeficiency virus type 1 (HIV-1). Therefore, we examined liver sections from 15 consecutively autopsied patients with AIDS for the presence of HIV-1 antigens p24 (core) and gp41 (envelope) by the avidin-biotin-peroxidase complex method using monoclonal antibodies. The most common histologic abnormalities noted were steatosis, portal inflammation, Kupffer cell hyperplasia, and focal hepatocellular and bile duct damage. Intra-hepatic opportunistic organisms were detected in six of 15 (40%) cases, with Mycobacterium avium-intracellulare being the commonest (four cases). Immunoreactivity for HIV-1 antigens was demonstrated in 12 of 15 cases (80%), with staining limited to Kupffer cells and other mononuclear cells characterized by a lymphoid morphology. Approximately the same number and type of cells were stained with both monoclonal antibodies and did not bear any relation to the degree of histologic abnormalities nor to the presence of opportunistic infections. The data suggest that some pathologic changes in AIDS livers are more likely the result of an indirect effect mediated by infected resident and circulating mononuclear cells than a direct cytopathic effect of HIV-1.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Liver disease in rhesus monkeys infected with simian immunodeficiency virus.

Rhesus monkeys infected with simian immunodeficiency virus (SIV) develop a syndrome very similar to patients with acquired immune deficiency (AIDS), including liver disease. This prospective study was undertaken to define the pathology, course, and pathogenesis of liver disease in 20 rhesus monkeys (Macaca mulatta) after intravenous inoculation with the standardized isolate SIV/DeltaB670. Tissue samples from liver and gallbladder between 2 and 24 weeks after inoculation were examined histologically and immunohistochemically for SIV gag protein p26, and by in situ hybridization with an SIV riboprobe. Histologically there was infiltration of portal tracts and around hepatic veins and venules by mononuclear inflammatory cells, focal bile duct damage, proliferation of bile ductules, and focal lobular inflammation as early as 2 weeks after infection. The severity and extent of these lesions were graded semiquantitatively and showed that bile duct damage and hepatic venulitis were the most significant changes. Simian immunodeficiency virus gag protein p26 and SIV RNA were detected in scattered mononuclear cells in portal tracts and sinusoids, but not in hepatocytes or bile duct epithelial cells. The data indicate that the liver is involved early during the course of SIV infection, followed by persistent changes until the terminal stage of the disease. Our findings suggest that the liver damage in SIV-infected rhesus monkeys is similar to the changes observed previously in AIDS patients.

Animals↗
PubMed1991

Community-wide outbreak of group G streptococcal pharyngitis.

Although several outbreaks of group G beta-hemolytic streptococcal (GGBHS) pharyngitis have been described, doubt still remains regarding the etiologic role of GGBHS in acute pharyngitis beyond a limited number of situations. In the winter/spring of 1986/87, throat cultures were obtained from 222 consecutive children seen at a private pediatric office with acute pharyngitis and group A beta-hemolytic streptococci (GABHS) were recovered from 91 children (41%) and GGBHS from 56 children (25%). One patient had both GABHS and GGBHS isolated. This isolation rate of GGBHS was dramatically greater than in previous and subsequent years, and 67% of the GGBHS isolates occurred during an 8-week period. Results of DNA fingerprinting of the 57 isolates of GGBHS demonstrated that 43 (75%) appeared to be the same strain. The patients with GGBHS were comparable to those with GABHS with respect to clinical findings, antistreptolysin-O titer response, and clinical response to antibiotic therapy. However, patients with GGBHS were significantly older (P less than .05). This is the first well-documented, community-wide outbreak of GGBHS pharyngitis and the first respiratory outbreak of GGBHS pharyngitis in a pediatric population. GGBHS may be a more important cause of acute, treatable pharyngitis than had been previously recognized.

Adolescent↗
PubMed1990

Lack of impact of early antibiotic therapy for streptococcal pharyngitis on recurrence rates.

To determine whether recurrence rates for group A beta-hemolytic streptococcal (GABHS) pharyngitis are related to the time of initiation of antibiotic therapy, we randomly assigned 113 patients with GABHS pharyngitis either to a group that began a 10-day course of penicillin V at the time of diagnosis or to a group that began the same antibiotic regimen after a dealy of 48 hours. Follow-up throat culture specimens were obtained 4 days, 2 months, and 4 months after the completion of antibiotic therapy, as well as during any interim episodes of acute pharyngitis. Serotyping of all GABHS isolates was performed to distinguish between recurrences with homologous serotypes and new acquisitions with heterologous serotypes. There was no significant difference between the two treatment groups in age, gender, duration of illness before enrollment in the study, initial clinical presentation, or compliance. Of the 50 patients in the immediate-treatment group, 6 (12%) had homologous serotypes of GABHS isolated on one of the follow-up throat cultures. Of the 63 patients in the delayed-treatment group, 9 (14%) had homologous serotypes of GABHS isolated on one of the follow-up throat cultures. These data indicate that a 48-hour delay in the initiation of penicillin therapy for GABHS pharyngitis does not reduce the recurrence rate.

Adolescent↗
PubMed1990

Evaluation of a new latex agglutination test for detection of streptolysin O antibodies.

Acute- and convalescent-phase serum specimens were collected from 50 patients with group A streptococcal pharyngitis. The anti-streptolysin O (ASO) titer for each serum specimen was determined by using both the standard neutralization assay and the latex agglutination (LA) test (Rheumagen ASO; Biokit Inc., New Britain, Conn.). When the ASO titers derived by the two methods were compared, the correlation coefficient was 0.93. When the ability of the LA test to demonstrate a significant ASO titer rise (greater than or equal to 2 dilutions) was compared with that of the standard neutralization assay, the LA test had a sensitivity of 91%, a specificity of 86%, a positive predictive value of 83%, and a negative predictive value of 92%. Triplicate LA test determinations were performed on a subset of 31 serum specimens, and for 29 (94%), the repeated ASO titers were all within 1 dilution of each other; the width of the 95% confidence interval for the triplicate measurements of each serum specimen was +/- 32.8 IU. We found the Rheumagen ASO to be a simple, rapid LA procedure for measuring ASO titers that produces results that are highly reproducible, show little lot-to-lot variability, and are comparable to the ASO titers obtained with the standard neutralization assay.

Adolescent↗
PubMed1990

Liposome immunoassay for rapid identification of group A streptococci directly from throat swabs.

The Q Test Strep (Becton Dickinson and Co., Franklin Lakes, N.J.) is a new solid-phase liposome immunoassay for the rapid diagnosis of group A beta-hemolytic streptococcal pharyngitis. Compared with blood agar plate cultures, the Q Test Strep had a sensitivity of 91%, a specificity of 83%, a positive predictive value of 88%, and a negative predictive value of 87%. Liposome technology can be used to facilitate the rapid diagnosis of group A beta-hemolytic streptococcal pharyngitis.

Humans↗