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Biomedical subjects

J E Herrmann

Publications and source records attributed to J E Herrmann.

At least 37 records · Page 2Linked to original sources
PubMed1993

Etiology of acute diarrhea among United States military personnel deployed to South America and west Africa.

A study of acute diarrhea was conducted from 1985 to 1987 among U.S. military personnel participating in routine shipboard exercises in South America and West Africa and ground troops deployed to coastal Ecuador. An enteropathogen was identified in 146 (51%) of 289 acute cases of diarrhea. Enterotoxigenic Escherichia coli, found in 50 (17%) patients with diarrhea, was the most commonly identified enteropathogen. Viral enteropathogens were also found in a high percentage of acute cases of diarrhea: rotavirus was detected in 11% of the patients and Norwalk virus infection in 10%. Most enteric pathogens were acquired in equal frequencies in South America and West Africa, except for rotavirus infection which was identified more often in West Africa and enteroaggregative E. coli infection which was identified more often in South America. Bacterial enteropathogens were frequently resistant to trimethoprim/sulfamethoxazole, but no resistance to quinolone drugs was observed, indicating that quinolone drugs have become important agents for the treatment of diarrhea in South America and West Africa.

Acute Disease↗
PubMed1992

Detection of Norwalk virus in stool specimens by reverse transcriptase-polymerase chain reaction and nonradioactive oligoprobes.

A reverse transcriptase (RT)-polymerase chain reaction (PCR)-oligoprobe (OP), or RT-PCR-OP, method was developed for the detection of the Norwalk virus, which causes acute, epidemic gastroenteritis, in stool specimens. The Norwalk virus genome regions encoding the following two proteins were amplified by RT-PCR: the RNA polymerase (260-bp product) and a putative immunogenic protein (224-bp product). The resulting DNA fragments (amplicons) were hybridized to a digoxigenin-labeled internal OP specific to each amplicon. The detection limit of Norwalk virus, as determined by the endpoint of RT-PCR amplification for serially diluted, positive stool specimens, was similar to the actual virion titer as estimated by electron microscopy and at least 100-fold greater than the titer determined by radioimmunoassay (RIA). The RT-PCR-OP assay was specific for Norwalk virus and negative for other enteric viruses, including human and animal caliciviruses, hepatitis E virus, Snow Mountain agent, astroviruses, 16 human enteroviruses, and 5 human rotaviruses. Components of fecal specimens that interfere with RT-PCR were removed successfully by Sephadex G-200 gel chromatography. Of 20 stool specimens from human volunteers that were positive for Norwalk virus by RIA, a specific RT-PCR-OP result was obtained in 95% (19 of 20) of the samples by using the immunogenic protein primers and 75% (15 of 20) by using the polymerase primers. Twenty-six stool specimens from asymptomatic children and adults were negative by the Norwalk virus RT-PCR-OP. RT-PCR-OP detected Norwalk virus in the 4 of 21 coded fecal specimens that were also positive by enzyme immunoassay. Two samples that were positive by RIA or enzyme immunoassay were negative by RT-PCR, perhaps because viral RNA was not present or RT-PCR inhibitors were not adequately removed.

Adult↗
PubMed1992

Astrovirus-associated diarrhea among Guatemalan ambulatory rural children.

Fecal excretion of astroviruses was monitored in 321 children, 0 to 3 years old, living in the rural highlands of Guatemala. During the longitudinal study, from February 1987 to February 1989, we examined 5,000 stool specimens, including 1,805 collected during 1,369 episodes of diarrhea, 830 collected during the convalescent week, and 216 and 244 collected 2 weeks and 1 week, respectively, before the onset of diarrhea. Routine specimens were taken once a month from every child who had been free from diarrhea for at least three consecutive weeks. Of the children, 124 (38.6%) excreted astroviruses during the study. In total, we identified 184 infections by astroviruses. Of the samples collected 2 weeks and 1 week before the initiation of symptoms, 0.9 and 4.9%, respectively, were positive, while 7.3% of the diarrhea episodes were associated with astroviruses. Of the convalescent specimens, 3.4% were shown to be positive; 2.4% of the 1,905 specimens taken in diarrhea-free periods contained astroviruses. Infections by other potential enteropathogens were documented in 54 and 65% of the asymptomatic and symptomatic astrovirus infections, respectively. Diarrhea associated with astroviruses alone had a median duration of 5 days and was associated with vomiting in 8.6%, with fever in 17.1%, with dehydration in 5.7%, and with loss of appetite in 34.3% of the episodes. Diarrhea due to astroviruses was accompanied by negative changes in weight gain. Astrovirus diarrhea contributes to the high morbidity observed in young children living under poor conditions and has a deleterious effect on their nutritional status.

Body Weight↗
PubMed1991

Astroviruses as a cause of gastroenteritis in children.

BACKGROUND: Infection with astroviruses has been associated with gastroenteritis in children, and serologic surveys indicate that this infection may be frequent. The importance of astroviruses as agents of gastroenteritis has not been shown in a controlled study, however. METHODS: We used monoclonal antibody-based enzyme immunoassays to detect astroviruses, enteric adenoviruses, and rotaviruses in stool samples obtained from age-matched children with and children without gastroenteritis. The samples were obtained in two studies, three years apart, among patients attending an outpatient clinic in Bangkok, Thailand. RESULTS: In the first study, astroviruses were detected in 8.6 percent (96 of 1111) of the children with gastroenteritis and in 2.0 percent (19 of 947) of the children without gastroenteritis. In the second study the rates were 8.6 percent (50 of 580) and 2.1 percent (11 of 512), respectively. For both studies combined, enteric adenoviruses were detected in 2.6 percent of those with gastroenteritis and in 0.5 percent of the controls, whereas rotaviruses were detected in 19 percent of those with gastroenteritis and in 1.0 percent of the controls. The clinical findings associated with astrovirus infection were similar to those associated with rotavirus infection, except for a trend toward greater dehydration in the children infected with rotaviruses. CONCLUSIONS: These two controlled studies involving a total of 3150 Thai children provide evidence that astroviruses are a common cause of viral gastroenteritis. Astroviruses were found in association with gastroenteritis more frequently than were enteric adenoviruses, and with nearly half the frequency of rotaviruses.

Adenoviruses, Human↗
PubMed1991

Astrovirus and adenovirus associated with diarrhea in children in day care settings.

The relative importance of astrovirus and adenoviruses as etiologic agents of diarrhea among children in day care was examined. Stool specimens from this prospective study were screened for both astrovirus and adenovirus hexon with two new indirect double-antibody assays and for enteric adenoviruses with an EIA specific for serotypes 40 and 41. Astrovirus was detected in a significantly greater percentage of children with diarrhea (4%, 21/524) than of those without (less than 1%, 1/138) (P less than .05); however, no difference between such such children with adenovirus infections was found (8%, 43/565, and 8%, 10/129, respectively). Overall, 30% (13/43) of all adenovirus hexon-positive specimens were enteric serotypes, and by extrapolation, enteric adenoviruses were identified in an equal percentage of children (2%) with and without diarrhea. This study documents the presence of astrovirus and enteric adenoviruses among children in day care in the United States, associates astrovirus with diarrhea in this setting, and suggests that viral agents may be the most common enteric pathogens among children with diarrhea in day care.

Adenovirus Infections, Human↗
PubMed1991

Detection of astrovirus in pediatric stool samples by immunoassay and RNA probe.

Two new astrovirus assays, a rapid biotin-avidin enzyme immunoassay (EIA) and RNA probe hybridization, were developed and compared with an established astrovirus assay, an indirect EIA, and immune electron microscopy. Sensitivity and specificity were evaluated by using a screening panel of 22 astrovirus-positive and 305 astrovirus-negative fecal specimens. The biotin-avidin assay was equivalent in performance to the reference indirect assay, and both could detect about 10 ng of viral protein. Although the probe was more sensitive than either EIA and could detect higher dilutions of virus in tissue culture and stool specimens, it did not detect more astrovirus-positive fecal specimens. Of the 22 astrovirus-positive specimens detected by the EIAs, 20 were confirmed by immune electron microscopy with hyperimmune rabbit antiserum. To determine the usefulness of EIAs for large epidemiologic studies, EIAs were used to screen 1,289 stool specimens from three studies of children with and without diarrhea. Astrovirus was detected in 3.5% of specimens from children with diarrhea and 1.9% of specimens from those without diarrhea. Our results indicate that the biotin-avidin EIA is an efficient, sensitive, and specific method for routinely screening large numbers of fecal samples and that its application in epidemiologic studies may yield higher rates of astrovirus infection than have been found previously by other methods.

Avidin↗
PubMed1991

Temporal synthesis of proteins and RNAs during human astrovirus infection of cultured cells.

Astroviruses are nonenveloped particles with a distinctive star-shaped surface structure that have been detected by electron microscopy in stool samples from humans and animals with gastroenteritis. We examined the patterns of macromolecular synthesis in astrovirus-infected cells with a goal of establishing a molecular basis for taxonomic classification. Trypsin is required for continuous replication of astrovirus in cultured cells; however, during a single cycle of infection, astrovirus antigen was synthesized earlier and at higher levels when serum, rather than trypsin, was included in the growth medium. This enhanced production of antigen, as measured by enzyme immunoassay, was accompanied by the appearance of aggregates of virus particles in the cytoplasm of infected cells. During astrovirus replication in cells cultured in the presence of serum, we detected a single infection-specific protein (90 kDa) beginning at 12 h postinfection. This protein was recognized by antiastrovirus rabbit serum and was sensitive to trypsin digestion in vitro, with the concomitant appearance of three smaller immunoreactive proteins (31, 29, and 20 kDa). We also detected two dactinomycin-resistant RNAs (7.2 and 2.8 kb), both of which were polyadenylated, in the cytoplasm of astrovirus-infected cells. The larger of these two RNAs is presumably the viral genome, whereas the smaller species may be a subgenomic messenger. Comparison of the proteins and RNAs synthesized in astrovirus-infected cells with those of the recognized families of nonenveloped single-stranded RNA animal viruses suggests that astroviruses should not be classified as members of either Caliciviridae or Picornaviridae.

Antigens, Viral↗
PubMed1990

Immunological characterization of the Marin County strain of astrovirus.

Marin County virus (MCV) was isolated from a stool suspension and serially propagated in human embryonic kidney cell cultures. MCV particles in stool and cell-propagated virus stocks showed reactivity by immune electron microscopy (IEM) with rabbit antiserum to astrovirus type 5. MCV antigen was also detected in two MCV stool samples by enzyme immunoassay (EIA) with an astrovirus group-specific monoclonal antibody. Acute and convalescent sera from 3 of 3 MCV-infected patients showed seroconversion to cell-propagated MCV by EIA. Immunofluorescence of MCV propagated in cell culture showed positive reactivity with an astrovirus group specific monoclonal antibody and astrovirus type 5 antiserum, with some cross-reactivity with astrovirus type 1. Similar results were obtained with the prototype strain of astrovirus type 5. However, in plaque-reduction assays, both the prototype astrovirus type 5 and MCV were neutralized by type 5 antiserum only. We conclude that MCV can be serially propagated by techniques used for previously described astroviruses and is serotypically an astrovirus type 5.

Antibodies, Monoclonal↗
PubMed1990

Effect of rimantadine on cytotoxic T lymphocyte responses and immunity to reinfection in mice infected with influenza A virus.

Administration of rimantadine to mice via drinking water, following a prophylactic dose, reduced lung virus titers by greater than 3 log10 plague-forming units (pfu)/ml but caused only marginal reductions in lung virus titers when therapy was started 8 h after exposure to virus. Mice given rimantadine prophylactically plus therapeutically were resistant to rechallenge with virus at a dose equivalent to that used for the primary infection (50 pfu/mouse) but not to a high dose (1 x 10(5) pfu/mouse). Virus-neutralizing-antibody titers were reduced only by rimantadine treatment, which included prophylaxis, whereas the cytotoxic T lymphocyte (CTL) response was depressed by treatment given with or without prophylaxis. Mice infected with rimantadine-resistant virus had no decrease in CTL or antibody responses when treated with rimantadine. Therefore, the depression in CTL and antibody responses associated with rimantadine treatment appears to be due to a decrease in the amount of viral antigen available or interference with viral antigen processing and not to nonspecific immunosuppressive effects.

Adamantane↗
PubMed1990

Diagnosis of astrovirus gastroenteritis by antigen detection with monoclonal antibodies.

An enzyme-linked immunosorbent assay (ELISA), based on monoclonal antibodies to the astrovirus group antigen, was designed for the detection of astroviruses in stools of patients with gastroenteritis. Compared to immune electron microscopy used as the standard test, the sensitivity of the astrovirus ELISA was 91% (31/34) and the specificity was 96% (54/56). All five of the known astrovirus serotypes could be detected in 16 samples on which serotyping was done. In tests on 155 stools containing other enteric viruses, including adenoviruses, rotaviruses, caliciviruses, Hawaii virus, Snow Mountain virus, and Norwalk virus (30, 20, 70, 24, 4, and 7 samples, respectively), only 3 were positive in the astrovirus ELISA. The combined specificity for all astrovirus immune electron microscopy-negative samples was 98% (206/211). The results demonstrate that the new ELISA provides a sensitive and specific means for the diagnosis of astrovirus gastroenteritis.

Antibodies, Monoclonal↗
PubMed1990

Accuracy of Chlamydia trachomatis antigen detection methods in a low-prevalence population in a primary care setting.

We compared a direct fluorescent-antibody stain (DFA) and an enzyme immunoassay (EIA) with a standard cell culture technique for the detection of Chlamydia trachomatis infection in women in an urban family practice setting. We also evaluated a DFA sample in a commercial laboratory to determine the interlaboratory reliability of this test. There were 268 women in the study; the EIA provided a higher sensitivity (83 versus 50%) and a higher positive predictive value (83 versus 69%) than the DFA test and comparably high specificity (99 versus 98%). Concordance between the two laboratories on the DFA test was not high when data were adjusted for chance agreement (kappa coefficient = 0.64). DFA validity was optimal with an elementary body cutoff of greater than 5, while EIA validity was optimal at the recommended cutoff of 0.1 optical density unit. None of 11 women with negative cultures after treatment had false-positive antigen tests. False-negative results with both tests were associated with low culture inclusion counts but were not strongly associated with the presence or absence of symptoms, menses, pregnancy, or recent antibiotic use. False-positive results with EIA were seen only for three women who had a chief complaint of vaginal discharge. Although the positive predictive value of DFA could be increased in high-prevalence subpopulations, EIA was still more valid in two such groups: teenagers and prenatal patients. These results indicate that EIA might be preferable for low- or moderate-prevalence populations in primary care settings and that a falloff in DFA sensitivity could be explained by lower infection burdens in low-prevalence groups.

Adult↗
PubMed1989

Plaque quantitation and virus neutralization assays for human astroviruses.

Astroviruses, 28 nm-diameter, RNA-containing viruses which have been implicated in gastroenteritis can be cultivated in cell cultures containing trypsin, but do not show distinguishable cytopathic effects. However, with the 5 known astrovirus serotypes which we have been able to cultivate, 3 (types 1, 2, and 5) formed well-defined plaques in LLCMK2 cell cultures under an agar overlay containing trypsin. A virus neutralization assay based on plaque reduction was applied to these 3 serotypes. It was found that rabbit antisera prepared against individual serotypes neutralized virus type-specifically, and no cross-neutralization titers were obtained with any of the antisera to the 5 astrovirus serotypes. The type-specific neutralization observed agreed with the specificities seen by immunofluorescence (IF), whereas ELISA tests with the same antisera show cross-reactivity among all 5 serotypes. There was no virus neutralization detected with astrovirus monoclonal antibodies which were reactive with 5 serotypes by ELISA and IF. The results we have obtained permit quantitative techniques to be applied to epidemiological and biological studies of the human astroviruses.

Antibodies, Viral↗
PubMed1989

Efficacy of rimantadine hydrochloride in the treatment of influenza infection of mice.

Rimantadine HCl was assessed for its effect on influenza A virus titer in lungs of infected BALB/c mice. Rimantadine administered orally via drinking water, with and without an intraperitoneal prophylactic loading dose, was compared to intraperitoneal administration. Mice were infected with a non-lethal dose of influenza A/Port Chalmers/H3N2 virus and the pulmonary virus titers were determined at intervals over a 21 day period. Prophylactic treatment with rimantadine followed by oral administration resulted in up to a 4 log10 reduction in pulmonary virus titer. The oral doses given to the mice were comparable on a mg/kg/day basis to those recommended for treatment of human infections. Reductions in pulmonary virus titers also occurred after intraperitoneal rimantadine treatment which included a prophylactic dose, but the reductions in pulmonary virus titers were less striking and not consistent over the course of infection. There were no significant reductions in pulmonary virus titers by either route if treatment was started 8 h after exposure to virus.

Adamantane↗
PubMed1989

Role of Norwalk virus in two foodborne outbreaks of gastroenteritis: definitive virus association.

Two separate food-associated outbreaks of gastroenteritis occurred among Erie County, New York residents in June 1986. In one outbreak, cases of illness were estimated to have occurred in 50% of the approximately 700 persons in 13 groups who ate at an out-of-county restaurant during a seven-day period, and, in the second outbreak, illness occurred in 26 (30%) of 87 persons who attended a graduation party held in a private home. Laboratory investigation included serology (blocking radioimmunoassay) to determine seroconversion to Norwalk virus and an enzyme immunoassay for detection of Norwalk virus antigen in stools, which the investigators have found to be more specific for Norwalk virus than serology. Seroconversion to Norwalk virus occurred in 11 (79%) of 14 restaurant-related cases and seven (100%) of seven graduation party cases. Seroconversion to Norwalk virus antigen was also found in four (40%) of 10 food handlers at the restaurant and in two (100%) of two food handlers at the graduation party. Antigen was detected in the stools of three (20%) of 15 restaurant-related cases and four (67%) of six graduation party cases. No stools for viral analyses were available for testing from food handlers. All seven of the patients with Norwalk virus-positive stools were also positive by seroconversion. Widespread availability of reagents for stool antigen detection would result in confirmation of more outbreaks due to Norwalk virus and in a more timely manner.

Disease Outbreaks↗
PubMed1988

Antigenic characterization of cell-cultivated astrovirus serotypes and development of astrovirus-specific monoclonal antibodies.

Cultivation of human astroviruses in human embryonic kidney or LLCMK2 cell cultures was corroborated for four of the five serotypes originally reported (types 1, 2, 4, and 5). By using type-specific rabbit antisera and immunofluorescence of virus-infected cells, we readily distinguished between serotypes of astrovirus; however, these serotypes showed a high degree of cross-reactivity by enzyme-linked immunoassay, a result indicating the presence of a group antigen. We prepared monoclonal antibodies to astrovirus type 2 antigen and selected them on the basis of group antigen reactivity. The antibodies were reactive with the four astrovirus serotypes that we could cultivate, as well as with the Marin County strain of astrovirus. A previously reported cell-cultivated astrovirus type 3 also reacted with the monoclonal antibodies. These monoclonal antibodies, and the finding of group reactivity among the human astroviruses, should facilitate studies on the importance of these viruses as agents of viral gastroenteritis.

Animals↗
PubMed1988

Application of DNA hybridization techniques in the assessment of diarrheal disease among refugees in Thailand.

The epidemiology and etiology of acute diarrheal disease were determined in a Hmong refugee camp on the Thai-Laotian border from April 11 to May 14, 1985. DNA hybridization techniques were used to detect Shigella species, enteroinvasive Escherichia coli, and enterotoxigenic E. coli. A monoclonal enzyme-linked immunosorbent assay was used to detect rotavirus, and standard microbiology was used to detect other enteropathogens. The age-specific diarrheal disease rates were 47 episodes per month per 1,000 children less than five years old and 113 episodes per month per 1,000 children less than one year old. Rotavirus, enterotoxigenic E. coli, Campylobacter, and Cryptosporidium were the predominant pathogens in children less than two years old. The DNA probe hybridized with 94% of 31 specimens identified as enterotoxigenic E. coli by the standard assays and with none of the specimens in which the standard assays were negative. The probe for Shigella and enteroinvasive E. coli hybridized in eight of 10 stools that contained Shigella and four of 314 stools from which Shigella and enteroinvasive E. coli were not isolated. The use of DNA probes allows specimens to be collected in remote areas with a minimum amount of equipment and technical expertise so that they can be easily transported to a central laboratory for further processing.

Acute Disease↗
PubMed1988

Isolation and propagation of enteric adenoviruses in HEp-2 cells.

Eighty-two stool samples from children with gastroenteritis in Canada, England, and Thailand which had been shown to contain adenovirus antigen (by a group-specific enzyme-linked immunosorbent assay) or adenovirus particles (by electron microscopy) or both, were tested for primary isolation of enteric adenoviruses in HEp-2 and Graham 293 cells. Graham 293 cells are known to support the replication of enteric adenovirus types (Ad40 and Ad41) on primary isolation, whereas HEp-2 cells reportedly do not. Of the 82 adenovirus isolates, 73 could be typed as Ad40 or Ad41 by type-specific monoclonal antibody enzyme-linked immunosorbent assay and by analysis of SmaI endonuclease digests. Of these 73, 30 (41%) could be isolated in HEp-2 cells, which included 43% (9/21) of those typed as Ad40 and 40% (21/52) of those typed as Ad41. On the basis of these results, the growth characteristics of adenoviruses in HEp-2 cell cultures, commonly used to distinguish enteric from nonenteric adenovirus types, are not valid for either diagnosis or epidemiological studies. For the samples studied here, use of these nondefinitive criteria would result in underestimation of the incidence of enteric adenoviruses in viral gastroenteritis.

Adenoviridae Infections↗