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Biomedical subjects

R E Bailey

Publications and source records attributed to R E Bailey.

At least 37 records · Page 2Linked to original sources
PubMed1987

Detection of St. Louis encephalitis virus antigen in mosquitoes by capture enzyme immunoassay.

Surveillance methods that measure St. Louis encephalitis (SLE) virus activity in nature may provide forewarning of its epidemic occurrence in humans. An antigen capture enzyme immunoassay was developed to detect SLE virus in infected mosquitoes. The assay detected purified SLE viral antigen at a concentration of 62 pg/0.1 ml when antigen was incubated overnight; 250 pg/0.1 ml was detected in a single-day assay (antigen incubated for 3 h). The assay detected 67.9 and 70.8% of laboratory-prepared pools of infected mosquitoes after 3 h and overnight incubation, respectively. The sensitivity of the procedure was 90.5% in identifying pools with infectious titers greater than dex 3.0. The specificity of the assay was controlled by retesting positive pools preincubated with SLE virus and normal antibodies, which led to a diminution of signal in the pools containing viral antigen. The procedure was suitably specific in discriminating between SLE and related flaviviruses, detecting only high infectious doses of heterologous antigens.

Animals↗
PubMed1987

Effects of ethanol on gastric epithelial cell phospholipid dynamics and cellular function.

The lipid profile of isolated gastric superficial epithelial cells (SEC) was evaluated by proton nuclear magnetic resonance spectroscopy (1H-NMR). The most conspicuous resonance band in SEC spectra was due to the protons of +N(CH3)3 groups of phosphatidylcholine and, to a lesser degree, other phospholipid derivatives, on the basis of their chemical shift and addition of purified phospholipids. NMR of cell lysates and phospholipid extracts of SEC in deutero-chloroform provided further spectral resolution of these components. Phospholipase or ethanol treatments of SEC produced membrane disorganization reflected as increased peak intensity of the phospholipid signals. In addition, ethanol, in a dose-dependent manner, attenuated paranitrophenyl phosphatase activity, which correlated with inhibition of total and ouabain-sensitive 86Rubidium chloride uptake by SEC. This study suggests that NMR used in conjunction with other biochemical techniques can monitor SEC membrane structure-function relationships. NMR is a potentially powerful noninvasive probe to show changes in lipid membrane organization induced by low concentrations of ethanol (1%) and may indicate an early sign of "cytotoxicity" in intact SEC.

4-Nitrophenylphosphatase↗
PubMed1986

NMR studies of pig gastric microsomal H+,K+-ATPase and phospholipid dynamics. Effects of ethanol perturbation.

The effects of ethanol on the gastric H+,K+-ATPase activity and the degree of mobility of various microsomal phospholipids were assessed using 31P and 1H NMR. This illuminated the role of lipid-protein association in the function of pig gastric microsomes. Treatment of gastric microsomes with 15% ethanol for 1 min at 37 degrees C inactivated the H+,K+-ATPase activity, which could largely be reconstituted by supplementation with phosphatidylcholine isolated from the gastric microsomes. Under similar conditions, the 1H NMR profile of the microsomal +N(CH3)3 choline moiety showed dramatic enhancement of peak intensity as well as a break point at 25 degrees C which was restored to the untreated control value after reconstitution. This break, together with the dramatic enhancement in the overall lipid profile, compared to the control and reconstituted microsomes, suggested a greater degree of freedom of movement of the microsomal lipids following ethanol perturbation. The data demonstrate the unique ability that a combined approach using 31P and 1H NMR holds as a noninvasive probe to study the structure-function relationship of biomembranes.

Adenosine Triphosphatases↗
PubMed1985

Dengue transmission in two Puerto Rican communities in 1982.

Paired serologic, entomologic, and environmental surveys were performed in two Puerto Rican communities, Salinas and Manatí, in summer and fall 1982. Paired samples on 434 persons in Salinas and 324 persons in Manatí showed recent dengue infection rates of 35% and 26%, respectively. Ae. aegypti larval indices were higher in Salinas than in Manatí but were relatively high throughout both communities. Breteau indices in neighborhoods ranged from 43 to 172, and infection rates in the neighborhoods were 22% to 45%. With a multivariate technique, we analyzed possible associations of environmental variables with dengue incidence and prevalence of dengue antibody. Wood-constructed housing and low socioeconomic status were among the variables significantly associated with dengue incidence. Predictors of dengue antibody prevalence included socioeconomic level, tree height, shade, and window and door screens. Recent dengue infections clustered within the sampled members of households (P less than 0.05, binomial test). An estimated 35% of dengue infections were symptomatic, and no serious illnesses were reported. The potential for high dengue infection rates in Puerto Rico will continue unless substantial reductions in vector populations are achieved. Targeting dengue surveillance and vector control activities in areas with demonstrated environmental risk factors may limit transmission during future outbreaks.

Adolescent↗
PubMed1984

Acute hemorrhagic conjunctivitis in Puerto Rico, 1981-1982.

In late 1981, the Western Hemisphere's pandemic of acute hemorrhagic conjunctivitis spread to Puerto Rico. Over 6,000 cases of conjunctivitis were reported to the Puerto Rico Department of Health from November 1981 to March 1982. Enterovirus 70 was isolated from one of 19 eye-swab specimens tested, and 10 of 13 (77%) individuals with acute hemorrhagic conjunctivitis had neutralizing antibody titers to enterovirus 70 of greater than or equal to 1:4. These data suggest that enterovirus 70 was the etiologic agent of the acute hemorrhagic conjunctivitis outbreak in Puerto Rico. In a study of a lower middle socioeconomic sector with relatively intense transmission, 152 of 670 (23%) persons reported illness consistent with acute hemorrhagic conjunctivitis. The highest attack rate was in the 5- to 14-year-old group (30%), and a disproportionate number of household index cases were in the predominantly school age group (5-19 years old). Twelve per cent (3/25) of asymptomatic household contacts of acute hemorrhagic conjunctivitis cases had sera with neutralizing antibody to enterovirus 70. Retrospective surveillance through ophthalmologists and neurologists identified one patient with a neurologic complication, a seventh nerve palsy temporally associated with recent enterovirus 70 infection. Household transmission was significantly associated with crowding and sharing of beds (p less than 0.05). This and other recent studies in Florida suggest that school age children play an important role in the transmission of acute hemorrhagic conjunctivitis. This study also suggests that asymptomatic enterovirus 70 infection is uncommon, and that in Puerto Rico, neurologic complications associated with acute hemorrhagic conjunctivitis were quite rare.

Adolescent↗
PubMed1984

Immunoglobulin M antibody capture enzyme-linked immunosorbent assay for diagnosis of St. Louis encephalitis.

Sera from patients with St. Louis encephalitis were tested with an immunoglobulin M (IgM) antibody capture enzyme immunoassay (MAC ELISA). The assay used five reagents: antihuman IgM, test serum, sucrose-acetone-extracted mouse brain antigen, broadly cross-reactive flavivirus monoclonal antibody conjugated to alkaline phosphatase, and substrate (p-nitrophenyl phosphate). MAC ELISA endpoint titers correlated (r = 0.893) with the absorbance value of a 1:100 dilution of patient serum. Significant (fourfold or greater) changes in the endpoint titers between paired sera corresponded to a critical ratio (ratio of absorbance values at the 1:100 dilution) of greater than or equal to 1.3. IgM antibodies were detected in 71% of patients bled at 0 to 3 days after the onset of illness, in 99% bled at 4 to 21 days, and in 91% bled at 22 to 67 days. Thereafter, the IgM seropositivity rate declined; however, 29% of sera were still positive at 115 to 251 days after the onset of illness. MAC ELISA titers were significantly correlated with hemagglutination inhibition (r = 0.258) and neutralization (r = 0.711) titers. Because IgM antibodies appeared early and waned rapidly, a diagnosis was made on the basis of a decrease in titer more often by MAC ELISA than by hemagglutination inhibition, complement fixation, or neutralization tests. IgM antibodies generally showed a high degree of specificity; heterologous cross-reactions were, however, present in 4 of 14 sera examined. The MAC ELISA is useful for the rapid, early diagnosis of St. Louis encephalitis.

Antibodies, Viral↗
PubMed1983

Symptomatic upper extremity venous thrombosis associated with permanent transvenous pacemaker electrodes.

Symptomatic arm vein thrombosis secondary to permanent transvenous cardiac pacing electrodes is an uncommon occurrence with an incidence of 1 to 3 percent. Two patients with this problem are presented who were treated with streptokinase followed by conventional anticoagulation therapy with heparin and warfarin. Near total resolution of the thromboses was accomplished in both patients. In follow-up periods of nine and 20 months, the patients have remained asymptomatic. An aggressive approach to this problem may decrease the current high morbidity.

Aged↗
PubMed1981

Serodiagnosis of La Crosse virus infections in humans.

Serological diagnoses of human infections with California serogroup viruses are usually made by means of complement fixation or hemagglutination inhibition tests or both. An analysis of antibody titers in sera from 128 humans with California (La Crosse) virus infections indicated that exclusive use of the complement fixation tests would have detected only 50% of the actual seroconversions, whereas hemagglutination inhibition and neutralization tests alone would have been sufficient to make the diagnosis in 79.3% and 84.8% of the cases, respectively. These and other results presented demonstrate that the complement fixation test is not sufficiently useful as a primary tool for diagnosis of La Crosse virus infections. We suggest the use of the hemagglutination inhibition test for preliminary screening of sera from individuals with suspect infections caused by California serogroup viruses. The neutralization test should then be used or confirmation and subtype identification. If hemagglutination inhibition and neutralization titers are high and stable, the complement fixation test should then be used as a last, but specific, resort.

Antibodies, Viral↗