Search PubMed⌕ Search

Biomedical subjects

R Yolken

Publications and source records attributed to R Yolken.

At least 37 records · Page 2Linked to original sources
PubMed1989

Monoclonal antibody solution hybridization assay for detection of human immunodeficiency virus nucleic acids.

In this report we describe a novel, nonisotopic hybridization assay for the measurement of viral RNA in biological samples. The assay involved a solution-phase reaction between a biotinylated DNA probe and RNA target sequences. Labeled hybrids were detected in an immunoreaction by using a solid-phase anti-biotin antibody and an enzyme-labeled monoclonal antibody specific for DNA-RNA hybrids. This monoclonal antibody solution hybridization assay was compared with an antigen-capture immunoassay for the detection of human immunodeficiency virus in 436 cell culture samples from 60 seropositive patients. The sensitivity and specificity of the hybridization assay were 93.5 and 94.6%, respectively. Detection of human immunodeficiency virus solely by hybridization in the initial sample but not subsequent samples from seven cultures may reflect detection of virus that was present in the patients' lymphocytes but did not replicate in vitro. Since the assay method is adapatable to the detection of either RNA or DNA, it could provide a means for the detection of a wide range of viral nucleic acids.

Antibodies, Monoclonal↗
PubMed1988

Effect of continued oral feeding on clinical and nutritional outcomes of acute diarrhea in children.

One hundred twenty-eight nonmalnourished male patients between 3 and 36 months of age were randomly assigned to receive one of four lactose-free dietary treatments to determine the effect of dietary therapy on the severity and nutritional outcome of diarrheal illness. Group 1 received a formula diet composed of casein, sucrose, dextrin with maltose (Dextri-Maltose), and vegetable oil to provide 110 kcal/kg body weight/d (CSO-110). Group 2 received CSO to provide 55 kcal/kg/d (CSO-55) for 2 days and then CSO-110. Group 3 received only oral glucose-electrolyte solution (GES) for 2 days, CSO-55 for the next 2 days, and then CSO-110. Group 4 received the same diets as Group 3 except that only intravenous GES was used for the first 2 days. The GES maintenance solutions provided 24 to 30 kcal/kg/d. Therapeutic success rates were similar among dietary groups, ranging from 90% to 97%. Fecal excretion was initially lower in group 4 (P less than 0.05) but was similar initially among groups treated orally and among all four groups beginning on day 3. Net apparent absorption of nitrogen, fat, carbohydrate, and total energy; retention of nitrogen; and increments in body weight, arm circumference, and skin-fold thickness were positively related to the amounts of dietary energy consumed. Thus continued oral feeding with the CSO diets during the early phase of therapy yielded improved nutritional results.

Absorption↗
PubMed1988

Enzyme immunoassay for detection of human immunodeficiency virus antigens in cell cultures.

A sensitive and specific avidin-biotin enzyme immunoassay that uses immunoreagents from naturally infected individuals was formulated for the detection of human immunodeficiency virus (HIV) antigens. A total of 500 cell culture samples from 111 cultures were tested in this assay and in a reverse transcriptase (RT) assay. Of 353 samples that were positive in the immunoassay, 174 were positive and 179 were negative in the RT assay. The specificity of the immunoassay results was supported by the failure of samples to react with nonimmune serum, by the ability of an anti-HIV type 1 monoclonal antibody to block the reactivity of selected samples, and by the appearance of RT activity in samples drawn from some cultures after a longer period of cultivation. HIV antigens were detected in 174 of 176 RT-positive samples (sensitivity, 98.9%). A comparison of the kinetics of antigen production and RT activity revealed that detectable antigen levels frequently preceded the appearance of RT activity. Thus, 50% of virus-containing cultures were identified within 9 days by immunoassay compared with 14 days by RT assay. In addition, RT activity was often detected intermittently in cultures sampled on several days, whereas antigen levels did not decline after initial appearance. Enzyme immunoassays for HIV antigen detection that use easily obtained reagents and simple technologies could facilitate laboratory and clinical research which requires cultivation of viruses.

Antibodies, Monoclonal↗
PubMed1988

Identification of a group-reactive epitope of group B rotaviruses recognized by monoclonal antibody and application to the development of a sensitive immunoassay for viral characterization.

Group B rotaviruses (GBRs) are fastidious agents which cause enteric disease in humans and a number of other animal species. Detailed study of the role of GBRs in human disease has been hampered by the lack of immunoreagents suitable for large-scale studies. We developed a monoclonal antibody which recognizes a group-reactive antigen contained in a number of strains of GBRs. When utilized in conjunction with a hyperimmune guinea pig antiserum to GBR, this monoclonal antibody can be used in an enzyme immunoassay system to detect a wide range of GBRs. Alternatively, this monoclonal antibody can be combined with sera obtained from GBR-infected animals to devise assays which are largely specific for the homologous strain of GBR. Reactivity was not noted in either system with strains of group A or group C rotaviruses or with other members of the family Reoviridae. These results indicate that GBRs contain both group-reactive and species-specific antigens which are distinct from those found in group A rotaviruses. The availability of well-defined immunoreagents will facilitate detailed studies of GBR infections in humans and animals.

Animals↗
PubMed1987

Epitope-specific immune responses to rotavirus vaccination.

Rotavirus gastroenteritis is a leading cause of infant mortality in developing countries and an important cause of morbidity in children under 2 yr of age in the United States. Vaccine programs have evaluated animal rotavirus strains that are attenuated in humans but antigenically similar to some human strains. Whether a single vaccine strain can elicit protective immunity in humans to rotaviruses of the same or different serotypes is an important question in determining vaccine efficacy. We used characterized serotype-specific monoclonal antibodies directed at VP7 in a competitive solid-phase immunoassay to measure epitope-specific immune responses to serotypes 1, 2, and 3 in sera of children who received a candidate serotype-3 rotavirus vaccine. Antibodies to serotype 3 were detected in 72% of sera samples, and to serotype 1 and 2 in only 11% each. Also, a VP3-specific monoclonal antibody which neutralizes three serotypically distinct strains of rotavirus was used to detect the presence of similar antibodies in 56% of the test sera. This finding suggests a mechanism of heterotypic immunity.

Antibodies, Monoclonal↗
PubMed1987

Specificity of dot hybridization assay in the presence of rRNA for detection of rotaviruses in clinical specimens.

Nucleic acid hybridization is used to identify viral genomic sequences in clinical and environmental samples. However, RNA virus genomes have been reported to hybridize to mammalian rRNA from uninfected cells under stringent conditions, and caution has therefore been advised in the use of nucleic acid probes for detection of RNA viruses. To evaluate the effect of rRNA on a diagnostic assay for an RNA virus, we tested the specificity of a rotavirus dot hybridization assay with clinical specimens which contained eucaryotic rRNA. The cDNA probe used in this assay contained sequences complementary to all 11 rotavirus genes. Preliminary experiments indicated that hybridization between rRNA and the cDNA probe occurred only with greater than 50 ng of rRNA, and this interaction was easily distinguished from the hybridization of the rotavirus probe with homologous or heterologous strains of the same rotavirus group. When 95 clinical specimens were tested, the rotavirus dot hybridization assay had a specificity of 98.8%. The predictive value of a negative test was 94.2%, although nearly all of the specimens contained rRNA and also reacted with an rRNA probe. Although the specificity of all dot hybridization assays should be individually evaluated, we conclude that our dot hybridization assay for rotaviruses is highly specific even in the presence of quantities of rRNA that may be anticipated in extracts of fecal specimens.

DNA, Viral↗
PubMed1986

Safety and immunogenicity of bovine rotavirus vaccine RIT 4237 in 3-month-old infants.

To assess the safety and immunogenicity of bovine rotavirus vaccine, we administered attenuated strain RIT 4237 to 54 inner-city infants randomized to one of three groups in a double-blind fashion to receive a dose at 3 and 5 months of age of either placebo, vaccine virus at 10(7) TCID50/ml, or vaccine virus at 10(8) TCID50/ml. Vaccination began in early fall 1984, and continued through spring 1985. Forty-nine infants received one dose of vaccine or placebo; 43 received both doses of vaccine or placebo. At 2 and 3 months after vaccination, homologous geometric mean neutralizing antibody titers were significantly higher in children who received either dose of vaccine compared with placebo recipients. Cumulative seroconversion to bovine rotavirus after either dose of vaccine virus was 87% at 6 months of age. Seroconversion was significantly higher (P less than 0.01) in both vaccine groups compared with the placebo group. No ill effects were associated with vaccine administration. RIT 4237 vaccine appears to be safe and immunogenic when administered to young infants living in the United States.

Animals↗
PubMed1986

T-cell-deficient mice display normal recovery from experimental rotavirus infection.

Rotaviruses are common causes of diarrhea in animals and humans. Little is known, however, about the components of the host response to these viruses. Rotavirus infection was studied in athymic mice experimentally infected with murine rotavirus. Neonatal T-cell-deficient mice experienced a self-limited gastrointestinal infection which was identical to that observed in age-matched immunocompetent mice. Adult T-cell-deficient seronegative mice and age-matched normal mice showed a similar extent of resistance to symptomatic rotavirus infection. In both cases, the infection was resolved without the generation of antirotavirus antibody. These studies indicate that host defense against murine rotavirus requires neither functional T-lymphocytes nor specific antiviral antibody.

Animals↗
PubMed1985

Detection of enteric adenoviruses by dot-blot hybridization using a molecularly cloned viral DNA probe.

Enteric adenoviruses (EAds) (candidate adenoviruses 40 and 41, subgroups F and G) have been implicated in the etiology of gastroenteritis in infants, but their clinical significance has been unclear because a rapid test to distinguish these agents from other adenovirus (Ad) types has not been available. We developed a dot-blot hybridization assay for EAd DNA using a cloned DNA fragment that has little homology to non-EAd DNAs. The dot-blot system detected less than 20 pg of EAd DNA, while showing minimal cross hybridization to representative strains from all other Ad groups. There was no detectable hybridization to extracts of samples known to contain other enteric viruses. It was further shown that low levels of EAds in specimens could be amplified by culturing for 1 day in 293 cells. Stool samples and tissue culture lysates prescreened by electron microscopy, cell culture or ELISA were tested in a blind fashion. Using endonuclease analysis as the standard for typing the isolates, we found the dot-blot system to have a 91% sensitivity and 71% specificity for detecting EAds and distinguishing them from other Ads. False-positive and equivocal dot-blot results appeared to be caused by other Ads.

Adenoviridae Infections↗
PubMed1985

Rapid diagnosis of viral infections: a new challenge for the pediatrician.

Pediatricians are likely to encounter a limited number of viruses causing a significant number of problems. Many of these infections, such as the common cold, do not currently require specific viral diagnosis. On the other hand, the rapid diagnosis of some viral infections has become clinically and epidemiologically more important as a result of improved understanding of viral transmissability and recent developments in preventive and therapeutic approaches. Concomitantly, several new diagnostic methods have been applied to many of these agents with increasing numbers of commercial kits. This double-edged sword of the predictably greater availability of means to obtain a rapid specific diagnosis of many viral infections, together with the various problems discussed here which can lead to erroneous management of patients, is becoming an important new challenge to the pediatrician.

Antibodies, Viral↗
PubMed1985

Role of soy-based, lactose-free formula during treatment of acute diarrhea.

A controlled study was conducted comparing the standard method of treating hospitalized infants with acute diarrhea (limited starvation) with the initiation of "early feeding" using a soy-based, lactose-free formula in infants of an American Indian tribe 12 months of age or younger. Forty-three patients, randomly assigned to group A, were given a soy-based, lactose-free formula four hours after hospitalization, and 44 patients, randomly assigned to group B, received standard therapy (food was withheld for the first 48 hours of hospitalization). After the first 48 hours, the same soy-based, lactose-free formula was given to the group B patients. Fluid intake and output of stool, urine, and vomitus were measured until the diarrhea resolved. Overall, group A patients showed less mean stool output (121 +/- 129 (SD) mL/kg) than group B patients (299 +/- 319 mL/kg) (P less than .001). Furthermore, the duration of illness was significantly shorter in group A patients (54 +/- 28 hours v 93 +/- 56 hours) (P less than .001). It was concluded that soy-based, lactose-free formulas can be safely used during the acute phase of diarrheal illness in infants and that their use shortens the duration of illness and decreases stool output in comparison with standard therapy.

Combined Modality Therapy↗
PubMed1984

A search for cytomegalovirus and herpes viral antigen in brains of schizophrenic patients.

The peroxidase-antiperoxidase method was employed to search for evidence of cytomegalovirus (CMV) or herpes simplex virus (HSV) antigen in the brains of 25 patients with a diagnosis of schizophrenia, 25 nonschizophrenic neuropsychiatric patients, and 16 nonpsychiatric control subjects. Brain specimens from patients with acute CMV and herpes encephalitis served as positive controls. Although early results with low-titer CMV antisera suggested immunoreactivity in specific brain regions of a small number of schizophrenic and control cases, the present studies with high-titer anti-CMV IgG did not give a positive immunoperoxidase reaction in sections from the basal forebrain, hypothalamus, or midbrain. Scattered neurons in the lateral vestibular nucleus and hippocampus showed questionable staining with CMV IgG in one schizophrenic patient and none in control subjects. No schizophrenic or control cases demonstrated an immune reaction to HSV antisera.

Adult↗
PubMed1983

Serum antibody response to toxins A and B of Clostridium difficile.

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to toxins A and B of Clostridium difficile was developed. Serum samples from 340 patients were tested for determination of the age-related prevalence of antitoxin. Antibody to toxin A was present in 64% of patients more than two years old and antibody to toxin B in 66% of patients more than six months old. A strongly positive ELISA value correlated with the presence of cytotoxicity-neutralizing antibody (P less than 0.001). Strongly positive ELISA values were obtained more commonly in convalescent sera from 16 patients with C difficile-induced colitis than in sera from the control population (antibody to toxin A, P less than 0.05; antibody to toxin B, P less than 0.001). Testing of paired sera revealed significant increases in the titer of IgG antibody to toxin A or B. Ten of the 16 patients with colitis had IgM titers of greater than or equal to 1:160 to one or both toxins. The data presented suggest that antibodies to toxins A and B are present in the majority of older children and adults and that patients with C difficile-induced disease develop serologic responses to one or both toxins.

Adolescent↗
PubMed1982

Sudden infant death syndrome associated with rotavirus infection.

Rotavirus was detected in the stools of five children stricken with sudden infant death syndrome (SIDS) over a three-week period. While none of the children had acute gastroenteritis, four of the five had acute upper respiratory infections. Rotavirus was also identified in tracheal aspirates from two of the infants. Extensive investigations failed to reveal the presence of any other viruses or toxins in specimens obtained from the five children with SIDS. Rotavirus was not found in the stool specimens obtained from a control group of 36 infants including six who died of causes other than SIDS. Future attempts at the prevention of rotavirus infections should be directed at populations susceptible to sudden infant death syndrome.

Feces↗
PubMed1982

Enzyme-linked immunosorbent assay (ELISA) for the detection of antibody to cysticerci of Taenia solium.

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibody to cysticerci of Taenia solium has been developed that employs a pork muscle antigen control for the cysticercus test antigen, somewhat improving the serological distinction between infected and uninfected subjects. Serum antibody to cysticercus was detected in 79% of classical neurocysticercosis patients from Mexico, and in 61% of a group of cysticercosis patients with an unusually rapid invasion of the central nervous system in an endemic focus of disease in Irian Jaya. Antibody was absent in a group of healthy American laboratory personnel, and in residents of a non-endemic region of Papua New Guinea. Additional test on sera from patients with other parasitic diseases showed that cross-reactivity may occur in some patients with schistosomiasis, echinococcosis, and possibly angiostrongyliasis; however, these parasites are not known to cause human infection in Irian Jaya.

Animals↗
PubMed1982

Clostridium difficile in normal infants and sudden infant death syndrome: an association with infant formula feeding.

Large numbers Clostridium difficile were found in the stools of two victims of sudden infant death syndrome (SIDS). This prompted a study of normal infants in the SIDS age group. Thirty-two infants were studied, using two selective culture techniques and two assays for bacterial products. Thirteen of the normal infants (39%) were found to carry C difficile, and fecal toxins were detected in eight of these, four with cytotoxin detectable at 10(-4) or higher dilution. Colonization was observed in one of 13 (7%) breast-fed babies and 12 of 17 (71%) of those whose primary milk source was infant formula (P less than .01). Fecal C difficile toxin was detected only in the latter group. The isolation of C difficile or its toxins in the stools of infants with SIDS, diarrhea, or even if large quantities of fecal cytotoxin are present.

Antigens, Bacterial↗