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Biomedical subjects

R Yolken

Publications and source records attributed to R Yolken.

At least 19 recordsLinked to original sources
PubMed2007

Reduced expression of human endogenous retrovirus (HERV)-W GAG protein in the cingulate gyrus and hippocampus in schizophrenia, bipolar disorder, and depression.

The human endogenous retrovirus (HERV)-W multicopy family was identified in human DNA from the previously characterized multiple sclerosis associated retroviral element (MSRV). Upregulation of the HERV-W POL has been reported in cerebrospinal fluid of patients with schizophrenia. The expression of capsid (GAG) protein of HERV-W was studied by immunohistochemistry and western blotting in postmortem brain tissue of the anterior cingulate cortex and hippocampal formation of normal controls and of patients with schizophrenia, bipolar disorder and major depression. A physiological expression of GAG protein was detected in neurons as well as astroglial cells in normal brain both in the anterior cingulate cortex and in the hippocampal formation. There was a statistically significant reduction of this expression in neurons and astroglial cells in brains from individuals with schizophrenia, major depression, and bipolar disorder. The results from the present study confirm that GAG protein encoded by the HERV-W multicopy gene family is expressed in cells of the central nervous system under normal conditions. Our findings of a cell type-, brain region- and disease-specific reduced expression in schizophrenia, major depression, and bipolar disorder are compatible with a pathophysiological role of HERVs in human brain disorders. The causes and biological consequences of this differential regulation will be the subject of further investigations.

Astrocytes↗
PubMed1996

Analysis of the DRPLA triplet repeat in brain tissue and leukocytes from schizophrenics.

An expansion of the CAG triplet in the human gene called atrophin-1 or CTG-B37 causes the neuropsychiatric disease known as dentatorubral-pallidoluysian atrophy (DRPLA). We have examined the genomic DNA from brains and peripheral blood leukocytes (PBLs) of schizophrenic and non-schizophrenic individuals and PBLs from a cohort of monozygotic twins discordant or concordant for schizophrenia, for expansions of the CTG-B37 region. All samples, including non-schizophrenic/normal controls, had 7-22 CAG repeats in this region. Thus we found no evidence for an expansion of the DRPLA triplet repeat associated with schizophrenia when compared to controls. Our data suggest that an expansion in the CTG-B37 gene is not linked to or responsible for the disease schizophrenia.

Alleles↗
PubMed1995

Diarrhoeal diseases in the White Mountain Apaches: clinical studies.

Acute diarrhoeal diseases continue to be a major health problem in certain underprivileged populations in the United States, including native Americans living in reservations. To describe the features of patients with diarrhoeal diseases requiring medical care, those attending the medical facilities of the Fort Apache Indian Reservation, Whiteriver, Arizona, were studied during 1981-1985. Clinical and aetiological information was obtained on 535 patients which constitute a 20% sample of those attending the outpatient clinic and all 386 patients who required 550 hospitalizations. Rotavirus, enterotoxigenic Escherichia coli, and Shigella were the most common aetiologic agents, a pattern similar to that seen in the developing countries. The clinical features of diarrhoeal illness and the frequent associated occurrence of acute respiratory symptoms, however, were remarkably similar, regardless of aetiology.

Acute Disease↗
PubMed1995

Diarrhoeal diseases in the White Mountain Apaches: epidemiologic studies.

Acute diarrhoeal disease in children is known to be a major public health problem among native Americans living in reservations in the southwestern part of the United States. This study was undertaken to describe the epidemiology and causative agents of diarrhoea more completely, with the expectation that this information may help in the ultimate control of the disease in this population. Three interrelated epidemiologic studies were carried out in the White Mountain Apache Tribe, Whiteriver, Arizona, during 1981-1985: a three-year longitudinal study on a cohort of 112 newborns, a longitudinal two-year study in a cohort of 200 families, and a case-control study on 1,072 children with diarrhoea attending a medical facility. Both epidemiologic and microbiological patterns of diarrhoeal disease were found to be very similar to those seen in developing countries, indicating the need for basic improvements in sanitation and hygiene in this population.

Acute Disease↗
PubMed1993

Quantitative polymerase chain reaction by monitoring enzymatic activity of DNA polymerase.

Nucleic acid amplification by polymerase chain reaction (PCR) is a very powerful technique in terms of sensitivity but is limited in terms of ability to perform accurate quantitation. While there is a theoretical correlation between copies of input target sequence and those of PCR product, the quantitative nature of this relationship is obscured by unpredictable variations in reaction conditions and by inhibitory and/or stimulatory substances which might be present in sample preparations, especially those derived from biological fluids. To reliably estimate copies of input DNA target from PCR product, we designed a combination of internal and external control systems coupled to DNA/RNA hybridization and enzymatic immunodetection techniques. The internal control system served to monitor amplification efficiency and to correct for the effects of inhibitors or stimuli on the efficiency of the DNA amplification. The assay is quantitative, nonisotopic, and can be widely applied to assessment of the quantity of DNA present in a wide range of preparations.

Base Sequence↗
PubMed1993

Quantitative measurement of nonisotopically labeled polymerase chain reaction product.

A novel approach for evaluation of polymerase chain reaction product was described. A biotin-labeled DNA (or RNA) probe is hybridized to the digoxigenin-labeled target PCR product. The hybrids are retained on an anti-biotin antibody-coated plate. An anti-digoxigenin Fab conjugated with alkaline phosphatase is used for generating either a fluorescence or a chromagenic substance. Both fluorogenic and chromagenic systems can be used for quantitative measurement of the PCR product/probe hybrids. The method is specific, fast, nonisotopic, sensitive, quantitative, and practical.

Base Sequence↗
PubMed1993

Prevalence of rotavirus on high-risk fomites in day-care facilities.

STUDY OBJECTIVE: The objective of this study was to determine the prevalence of rotavirus contamination on environmental surfaces in day-care environments, using the polymerase chain reaction technique. DESIGN: High-risk fomites were identified in two day-care centers and sampled biweekly during a 6-month study period. Water samples from water-play tables in each center were also collected during the study period. During an infectious disease outbreak, fomites were sampled from the rooms in which the outbreak occurred. Reverse transcriptase/polymerase chain reaction was carried out for viral detection of rotavirus from the fomites, and standard bacteriologic measures were used to detect bacteria in samples from water-play tables. RESULTS: A total of 96 fomite samples were tested for presence of rotavirus from the two centers, of which 18/96 (19%) tested positive for rotavirus. The timing of the positive samples differed between the two centers. In the center that housed infants, a peak of rotavirus-positive fomites coincided with two enteric outbreaks. Rotavirus contamination was found on the telephone receiver, drinking fountain, water-play table, and toilet handles in both centers. Bacteria in large quantities were also identified in water-play table samples. CONCLUSIONS: Moist surfaces including the telephone, water fountains, and water-play tables are common sources of rotavirus contamination within the day-care environment. Until a safe and affordable drug or vaccine against rotavirus is available for general use, avoidance of rotaviral infections is the most effective method for the prevention of rotavirus gastroenteritis.

Baltimore↗
PubMed1992

Use of modified nucleotides and uracil-DNA glycosylase (UNG) for the control of contamination in the PCR-based amplification of RNA.

The inadvertent carryover of amplified fragments of nucleic acids (amplicons) is a potential source of contamination in the polymerase chain reaction. Recently, a method has been developed to generate amplicons with deoxyuracil triphosphate (dUTP) and to specifically hydrolyze these amplicons with uracil-DNA glycosylase (UNG) following the completion of the assay. We evaluated this system for the specific amplification of RNA from coxsackievirus A3 and B3. We found that RNA from both viruses could be amplified with dUTP, although the use of this triphosphate in place of TTP resulted in some loss of assay sensitivity. We also found that the dUTP-containing amplicons could be efficiently hydrolyzed by UNG, resulting in a 10,000,000-fold reduction in amplicon concentration with little effect on the native nucleic acid. The dUTP-UNG method has a great deal of potential for reducing amplicon contamination during the routine performance of nucleic acid amplification reactions.

Artifacts↗
PubMed1992

Detection of rotaviruses in the day care environment by reverse transcriptase polymerase chain reaction.

Group A rotavirus is an important cause of morbidity among infants and toddlers in day care centers. Transmission by the fecal-oral route is well established, but fomites and environmental surfaces may also play an important role in transmission. A highly sensitive polymerase chain reaction (PCR) assay was used to detect rotavirus RNA in day care environments. Areas sampled included floors, diaper change areas, toy balls, and other surfaces. In two centers undergoing outbreaks of rotavirus, 7 (39%) of 18 toy balls had detectable rotavirus as did 8 (21%) of 39 swabs from environmental surfaces. By comparison, only 1 (5%) of 21 toy balls and 1 (2%) of 44 environmental surface swabs had detectable rotavirus in centers without rotavirus outbreaks (P = .0001). Thus, rotaviruses are highly prevalent in day care centers during outbreaks of diarrhea. The monitoring of environments by sensitive nucleic acid amplification techniques may lead to strategies for the diminution of disease transmission within the day care environment.

Base Sequence↗
PubMed1991

Improved detection of rotavirus shedding by polymerase chain reaction.

To improve identification of children excreting rotavirus a method for the amplification of rotavirus RNA by the polymerase chain reaction (PCR) was developed. The assay was compared with a solid-phase enzyme immunoassay in the detection of rotavirus shedding by infants in hospital during the winter peak of rotavirus infections. Forty children were studied in an intermediate care unit after transfer from intensive care units. Only two were admitted primarily because of diarrhoea; the other thirty-eight were admitted for management of various other disorders. Rotavirus shedding was detected by enzyme immunoassay in twenty of the infants, and nine of these (aged 1 week to 8 months) remained in hospital for more than 5 days after the initial detection of rotavirus and could be studied long term. Of 103 faecal samples from the nine infants, 60 (58%) contained rotavirus RNA detected by reverse-transcriptase (RT)/PCR, whereas only 37 (36%) were positive for rotavirus antigen by the immunoassay (chi 2 = 10.3, p less than 0.002). The geometric mean time of rotavirus shedding was 9.5 (range 1-19) days as detected by RT/PCR and 5.7 (range 1-17) days by the immunoassay (p less than 0.018). In five of the nine children, RT/PCR detected rotavirus shedding for 2-7 days longer than the immunoassay and in four children RT/PCR was positive 1 or more days before rotavirus antigen was detected. Further studies should attempt to find out whether infected infants are capable of spreading wild-type virus during periods when they are not shedding antigen as detectable by enzyme immunoassay.

Antigens, Viral↗
PubMed1991

Efficacy and pharmacokinetics of intravenous immune globulin administration to high-risk neonates.

UNLABELLED: OBJECTIVE--To determine whether intravenous immune globulin (IVIG) administration modifies the incidence of infections in high-risk neonates. DESIGN--Randomized, double-blind study. SETTING--Neonatal intensive care unit at a tertiary care center. PARTICIPANTS: A total of 170 infants were enrolled, 82 of whom received IVIG and 88 of whom received the placebo preparation. Infants were stratified by birth weight into one of three groups (category 1, those weighing less than 1000 g; category 2, those weighing between 1000 and 1500 g; and category 3, those weighing more than 1500 g). INTERVENTIONS--Intravenous immune globulin (750 mg/kg of body weight), or albumin placebo was administered within 72 hours of admission to the tertiary care center and every 14 days thereafter until discharge from the neonatal intensive care unit or age 3 months. Serum IgG levels were measured and data collected relating to the incidence of systemic and localized infections and to the course of hospitalization. MEASUREMENTS AND MAIN RESULTS--The administration of IVIG had no major side effects and resulted in higher serum IgG levels in infants in all birth weight categories compared with infants receiving the placebo. Systemic infections developed in five IVIG-treated infants and five placebo-treated infants. Administration of immunoglobulin had no significant effect on the rate of localized infections or necrotizing enterocolitis. It also did not affect hospital course of the infants as measured by length of hospitalization or the number of days on assisted ventilation, supplemental oxygen, or antibiotics was required. CONCLUSIONS--The general administration of IVIG using this dosage regimen has limited effects on the clinical course of infants in a neonatal intensive care unit.

Bacteremia↗
PubMed1991

Detection of animal and human group B rotaviruses in fecal specimens by polymerase chain reaction.

A combined reverse transcriptase reaction-polymerase chain reaction (RT-PCR) was developed to achieve the sensitive detection of group B rotaviruses (GBR). Sequences derived from genomic segment 3 of the IDIR (intestinal disease of infant rats) strain of GBR permitted the detection of greater than or equal to 0.08 pg of purified IDIR genomic RNA (4,000 genome copies). Primers complementary to the terminal sequences of gene 11 of GBR strain ADRV (adult diarrhea rotavirus) allowed for the detection of as little as 0.008 pg of purified ADRV genomic RNA. Detection of heterologous strains of GBR was also observed with these primer pairs. IDIR gene 3 primers recognized greater than or equal to 8 pg of RNA from bovine GBR obtained from a variety of geographic locations. RNA from IDIR, but not bovine GBR, strains was detected by means of RT-PCR with ADRV gene 11 primers. Neither set of GBR primers was reactive in RT-PCR with fecal specimens containing group A rotaviruses or fecal specimens from uninfected controls. This RT-PCR assay permits the sensitive and specific detection of a variety of GBR in fecal specimens.

Animals↗
PubMed1990

Immunoglobulins and other modalities for the prevention and treatment of enteric viral infections.

Viral infections of the gastrointestinal tract constitute a major health problem during the first years of life. In addition to causing acute diarrhea, rotaviruses and other enteric viruses may be involved in the pathogenesis of necrotizing enterocolitis and other neonatal enteric diseases. There are several potential methods for the prevention and treatment of gastrointestinal viral infections. Antiviral immune globulins, administered by the parenteral or oral route, might prove useful for the inhibition of intestinal viral replication. Alternatively, specific glycoprotein inhibitors of viral-cell binding might be used to prevent the productive infection of intestinal epithelial cells. In addition, since many enteric viruses require proteolytic enzymes for protein cleavage, protease inhibitors may prove to be effective agents for the inhibition of intestinal viral replication. At this point in time, these methods have proven useful for the inhibition of rotavirus infection in experimental animals. The successful application of these and other methods for the prevention of enteric infections in humans might substantially reduce the morbidity and mortality associated with enteric diseases.

Animals↗
PubMed1990

Occurrence of infectious symptoms in children in day care homes.

Transmission of enteric pathogens is facilitated in child day care centers, including family day care homes, by frequent and intimate exposure among susceptible hosts, with diaper changing as the highest-risk procedure for such transmission. The objective of this study was to evaluate the effectiveness of an intervention program in decreasing the incidence of infectious disease symptoms in children attending family day care homes during a 12-month period. Each of 24 family day care homes was randomly assigned to an intervention or control group. The intervention included four components: (1) a handwashing educational program and (2) use of vinyl gloves, (3) use of disposable diaper changing pads, and (4) use of an alcohol-based hand rinse by the day care provider. Symptoms of enteric disease (diarrhea and vomiting) were significantly reduced in intervention family day care homes (p less than or equal to 0.05), whereas respiratory symptoms were not significantly different between intervention and control family day care homes (p = 0.35). Diarrhea was reported in 1 of every 100 child care days, representing one diarrhea episode per month in a typical family day care home.

1-Propanol↗
PubMed1990

Enzyme immunoassay for detection of hybrids between PCR-amplified HIV-1 DNA and a RNA probe: PCR-EIA.

An enzyme immunoassay was developed to detect human immunodeficiency virus type 1 (HIV-1) DNA amplified by polymerase chain reaction (PCR-EIA). A set of primers (outer set) was used in PCR to amplify a segment of the HIV-1 gag gene from peripheral blood mononuclear cells. Hybrids between the amplified DNA and a RNA probe were measured in a microtiter plate immunoassay using a beta-D-galactosidase-conjugated monoclonal antibody to DNA-RNA hybrids and a fluorescent substrate. A second set of primers (nested set) located within the outer set was used in PCR with a known template to prepare the probe. One primer of the nested set included the T7 RNA polymerase promoter at its 5' end allowing transcription of a single-stranded RNA probe. Ten copies of HIV-1 DNA could be detected by PCR-EIA (42 fluorescent units with a background of 18 fluorescent units) compared with a detection limit of 1000 copies by ethidium bromide-stained agarose gel. HIV-1 DNA was detected by PCR-EIA in peripheral blood mononuclear cells from 32 of 33 seropositive patients (range 54-810 fluorescent units), and 0 of 25 seronegative patients (range 20-40 fluorescent units) (sensitivity 97%; specificity 100%). PCR-EIA offers a practical and nonisotopic method to objectively measure PCR-amplified HIV-1 DNA and has the potential for the measurement of other microbial pathogens in human body fluids.

Base Sequence↗
PubMed1990

Removal of inhibitory substances from human fecal specimens for detection of group A rotaviruses by reverse transcriptase and polymerase chain reactions.

A method was developed for the purification of rotavirus RNA from fecal extracts in order to permit the sensitive identification of group A rotavirus in fecal specimens by the polymerase chain reaction. Sequential reactions with reverse transcriptase and Taq polymerase with directed primers from rotavirus gene 6 yielded characteristic 259-base-pair fragments that were then visualized by silver stain on a polyacrylamide gel. As few as 500 genomic copies of purified rotavirus RNA could be detected in this manner. However, when the method was applied to fecal samples with added rotavirus virions, inhibition was noted in many of the fecal extracts which were tested. The inhibition could be reversed by dilution of the fecal extract, but sensitivity was also reduced by a corresponding dilutional factor. The inhibition was quantitatively removed by an added step in the extraction process that utilized chromatographic cellulose fiber powder (CF11 powder) to purify the rotavirus RNA during a series of rapid washing and elution steps. After CF11 purification, rotavirus RNA could be detected in experimental fecal samples at dilutions 1,000- to 10,000-fold beyond the detection limits of standard techniques such as enzyme immunoassay and the direct visualization of RNA following polyacrylamide gel electrophoresis. Furthermore, following purification by CF11, rotavirus RNA could be detected in all of seven enzyme-linked immunosorbent assay-positive fecal samples obtained from a child with rotavirus gastroenteritis; when CF11 purification was not performed, rotavirus RNA could be detected in only four of these samples, even after the removal of inhibitors by dilution of the extracts. Large-scale identification of rotavirus in fecal specimens may be possible by use of CF11 purification of viral RNA prior to sequential reactions with reverse transcriptase and Taq polymerase in a modified polymerase chain reaction.

Feces↗
PubMed1989

Infantile gastroenteritis associated with excretion of pestivirus antigens.

Faeces from children under 2 years old who had gastroenteritis that could not be attributed to recognised enteric pathogens were examined with a monoclonal-antibody-based immunoassay for Pestivirus antigens. Such antigens were detected in 30 of 128 episodes of gastroenteritis. Children without diarrhoeal disease and children infected with rotaviruses had little evidence of Pestivirus infection (faeces positive in 1 of 28 and 1 of 31, respectively). The diarrhoeal disease in children excreting Pestivirus antigens resembled that in other children except that it was more commonly associated with signs and symptoms of respiratory inflammation.

Antibodies, Monoclonal↗