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Biomedical subjects

C B Hall

Publications and source records attributed to C B Hall.

At least 73 records · Page 4Linked to original sources
PubMed1993

Human herpesvirus-6.

Human herpesvirus-6 (HHV-6), a mature T-cell lymphotropic virus, is a newly recognized member of the herpes virus family and shares limited homology with human cytomegalovirus. HHV-6 has been identified as the etiologic agent of the childhood illness exanthem subitum (roseola infantum). Widespread acquisition of this virus has been demonstrated to occur early in childhood, with fever as the most consistent manifestation of primary infection. Reactivation of latent infection has been postulated and may be associated with lymphoproliferative disorders or other diseases of immune function.

Exanthema Subitum↗
PubMed1993

Missed opportunities for childhood vaccinations in office practices and the effect on vaccination status.

To determine the rate of childhood under-vaccination, rate and types of missed opportunities (MOs) for vaccinations, and the contribution of MOs to the undervaccination of preschool-age children, the authors conducted a retrospective medical chart review in seven primary care settings in the Rochester, NY, area: a hospital clinic, a neighborhood health center, a group-model health maintenance organization, an urban group practice, a suburban group practice, a rural health center, and a rural private practice. The random sample included 1124 children having birth dates between March 15, 1988, and September 15, 1989. The main outcome measures were cumulative undervaccination rate, defined as the proportion of patients from each practice who were ever > 60 days past-due for a vaccination by 12, 18, or 24 months of age; undervaccination time, defined as the median number of months during which children were undervaccinated; number of MOs; visit types and conditions associated with the MOs; and the duration of undervaccination time attributable to MOs. The cumulative undervaccination rate by 12 months was at least 20% in each practice except for the suburban practice, where it was 4%. The frequency of MOs varied from a high of 1.8 MO per patient per year at the rural private practice to a low of 0.3 MO per patient per year at the suburban practice. More than one quarter of MOs occurred during either health supervision or follow-up visits in all practices. In 28% of visits during which an MO occurred, patients had no fever or acute illness.(ABSTRACT TRUNCATED AT 250 WORDS)

Child Health Services↗
PubMed1993

Is an emergency department visit a marker for undervaccination and missed vaccination opportunities among children who have access to primary care?

The purpose of this study was to determine: (1) whether preschool-age patients who utilize the emergency department (ED) are undervaccinated compared with patients having the same primary care provider and (2) whether reducing missed vaccination opportunities in the primary care office can potentially reduce the differences in undervaccination between the groups. This retrospective cohort study involved two groups: 583 ED patients, aged 4 to 48 months, who had primary care providers; and 583 control subjects randomly selected from primary care sites and matched according to date of birth and primary care site. The major outcome variable was the point prevalence of undervaccination, defined as more than 60 days past due for a vaccine at the time of the ED visit, and for control subjects, at the time of their matched patient's ED visit. Demographic variables, vaccination history, presence of chronic illness, and office utilization history were abstracted from office charts. The mean age of all patients was 20.0 months. Emergency department patients were more likely to be boys (61% vs 50%) and had more chronic illness, but did not differ racially from those in the control group. Primary care sites included a hospital-based clinic (n = 137), neighborhood health centers (n = 172), and private practices (n = 274). The undervaccination rates by primary provider type were for (1) hospital clinic ED patients 21.1%, control subjects 19.7%; (2) neighborhood health center ED patients 29.1%, control subjects 22.7%; and (3) private practice ED patients 26.6%, control subjects 14.9%. Overall, the odds ratio of ED patients' being undervaccinated compared with control subjects was 1.8 (95% confidence interval 1.3 to 2.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1992

Primary human herpesvirus 6 infection in young children.

BACKGROUND: Human herpesvirus 6 (HHV-6) is a recently discovered virus that, on the basis of serologic evidence, appears to infect most children by the age of three years. However, the clinical manifestations of primary HHV-6 infection have not been well defined. METHODS: We studied consecutive children two years old or younger who presented to an emergency ward with febrile illnesses. Our evaluation included the isolation of HHV-6 from peripheral-blood mononuclear cells, an immunofluorescent-antibody assay, the detection of HHV-6 by the polymerase chain reaction (PCR), and restriction-endonuclease-fragment profiles of HHV-6 isolates. RESULTS: HHV-6 was isolated from 34 of 243 acutely ill children (14 percent). The children with viremia had irritability, high temperatures (mean, 39.7 degrees C), and inflammation of tympanic membranes (in 21), but few other localizing signs. Two children were hospitalized, but all 34 recovered after an average of four days of fever. The rash characteristic of roseola, which has been associated with HHV-6 infection, was noted in only three children. In 29 children (85 percent), serum samples obtained during convalescence had at least a fourfold increase in IgG antibody titers; 4 infants less than three months old who presumably had maternal antibody did not have this increase. HHV-6 was isolated from blood obtained during convalescence in only one child, but in two thirds of the children the virus could be detected by PCR. The isolates had genomic heterogeneity, indicating the presence of multiple strains. CONCLUSIONS: Primary infection with HHV-6 is a major cause of acute febrile illness in young children. Such infection is associated with varied clinical manifestations, viremia, and the frequent persistence of the viral genome in mononuclear cells.

Antibodies, Viral↗
PubMed1992

Phenotypic and genetic polymorphisms among human herpesvirus-6 isolates from North American infants.

Fifteen human herpesvirus-6 (HHV-6) isolates from North American infants with primary infection manifest as febrile or roseola (exanthem subitum) like illnesses were characterized phenotypically on the basis of their in vitro growth in continuous T-cell lines and primary human mononuclear cells and by their reactivity with monoclonal antibodies. All isolates replicated efficiently in primary human cord blood mononuclear cells, but five distinct patterns of viral replication in human cells lines were observed. Two of the HHV-6 isolates from infants were found to replicate in HSB-2 cells, a property associated with so-called group A viruses, which had previously been isolated only from adults. These same isolates also reacted with a panel of A-specific monoclonal antibodies. Genomic characterization of viral isolates using well-characterized restriction site polymorphisms indicated that these two isolates contained a mixture of both A- and B-type genomes, in different proportions. These data suggest that not all HHV-6 isolates can be categorized into one of two broad groups and that such segregation of HHV-6 isolates may in fact be misleading.

Cell Line↗
PubMed1992

Impaired thyroid hormone status and thermoregulation during cold exposure of zinc-deficient rats.

Forty-five male, weanling Sprague-Dawley rats were matched by weight into three groups (n = 15). One group was fed ad libitum a semipurified diet containing all essential nutrients and 30 ppm of zinc (control). A second group was fed ad libitum a similar diet but with a deficient zinc intake of less than 1 ppm (ZnD). A third group was pair-fed (PF) the control diet in amounts equal to that consumed by the matched ZnD animals. After 42 days, the animals were fasted for 12 hr then five animals from each group were sacrificed and the remainder was exposed to 3 degrees C for 6 hr. Rectal temperatures were lower (p less than 0.05) in ZnD at 23 degrees C and during cold exposure. Plasma thyroxine (T4) and triiodothyronine (T3) concentrations were reduced (p less than 0.05) at room temperature in ZnD rats. During cold exposure, the ZnD animals had depressed (p less than 0.05) plasma thyrotropin, T4 and T3 concentrations. Thus, ZnD adversely affects thermoregulatory performance of rats acutely exposed to cold by influencing thyroid hormone metabolism.

Adipose Tissue, Brown↗
PubMed1992

Evaluation of new anti-infective drugs for the treatment of respiratory tract infections. Infectious Diseases Society of America and the Food and Drug Administration.

These guidelines deal with the evaluation of anti-infective drugs for the treatment of respiratory tract infections. Five clinical entities are described: streptococcal pharyngitis and tonsillitis, otitis media, sinusitis, bronchitis, and pneumonia. A wide variety of microorganisms are potentially pathogenetic in these diseases; these guidelines focus on the bacterial infections. Inclusion of a patient in a trial of a new drug is based on the clinical entity, with the requirement that a reasonable attempt will be made to establish a specific microbial etiology. Microbiologic evaluation of efficacy requires isolation of the pathogen and testing for in vitro susceptibility. Alternatively, surrogate markers may be used to identify the etiologic agent. The efficacy of new drugs is evaluated with reference to anticipated response rates. Establishment of the microbial etiology of respiratory tract infections is hampered by the presence of "normal flora" of the nose, mouth, and pharynx, which may include asymptomatic carriage of potential pathogens. This issue is addressed for each category of infection described. For example, it is suggested that for initial phase 2 trials of acute otitis media and acute sinusitis tympanocentesis or direct sinus puncture be used to collect exudate for culture. Acute exacerbations of chronic bronchitis also present difficulties in the establishment of microbial etiology. These guidelines suggest that clinical trials employ an active control drug but leave open the possibility of a placebo-controlled trial. For pneumonia, the guidelines suggest the identification and enrollment of patients by the clinical type of pneumonia, e.g., atypical pneumonia or acute bacterial pneumonia, rather than by etiologic organism or according to whether it was community or hospital acquired. For each respiratory infection, the clinical response is judged as cure, failure, or indeterminate. Clinical improvement is not acceptable unless quantitative response measures can be applied.

Anti-Bacterial Agents↗
PubMed1991

Altered metabolic response of iron-deficient women during graded, maximal exercise.

Metabolic responses during a standardized, progressive, maximal work capacity test on a cycle ergometer were studied in 11 women, mean age 28 (SEM 2) years, at admission to the study, after their body iron stores were depleted by diet, phlebotomy and menstruation for about 80 days and after iron repletion by diet for about 100 days, including daily iron supplementation (0.9 mmol iron as ferrous sulfate) for the last 14 days of repletion. Iron depletion was characterized by a decline (P less than 0.05) in hemoglobin, ferritin and body iron balance. Iron repletion, including supplementation, increased (P less than 0.05) hemoglobin, ferritin and iron balance. No changes were observed in cardiovascular and ventilatory responses or peak oxygen uptake. Iron depletion was associated with a reduced (P less than 0.05) rate of oxygen utilization, total oxygen uptake and aerobic energy expenditure, and elevated (P less than 0.05) peak respiratory exchange ratio and post-exercise concentration of lactate. Reduction of body iron stores without overt anemia affects exercise metabolism by reducing total aerobic energy production and increasing glycolytic metabolism.

Adult↗
PubMed1991

Immunity to and frequency of reinfection with respiratory syncytial virus.

To better understand the duration of immunity against respiratory syncytial virus (RSV) and the role of serum antibodies to the surface glycoproteins, F and G, in susceptibility to reinfection, 15 adults with previous natural RSV infection were challenged with RSV of the same strain group (A) at 2, 4, 8, 14, 20, and 26 months after natural infection. By 2 months about one-half and by 8 months two-thirds of the subjects became reinfected. Each challenge resulted in infection in at least one-fourth of the subjects. Within 26 months 73% had two or more and 47% had three or more infections. The duration of immunity tended to increase after two closely spaced infections. Higher neutralizing, F and GA antibody levels before challenge correlated significantly with protection against infection. However, even in subjects with the highest antibody levels, the risk of reinfection was 25%. Specific nasal IgA antibody titers did not correlate significantly with protection. This suggests that humoral neutralizing, F, and G antibodies correlate with resistance to reinfection, but protection is far from complete and is of short duration.

Adult↗
PubMed1991

Use of intravenous gamma globulin to passively immunize high-risk children against respiratory syncytial virus: safety and pharmacokinetics. The RSVIG Study Group.

Infants with cardiopulmonary disease develop severe illness from respiratory syncytial virus (RSV) infection. Safety, feasibility, and pharmacokinetics of intravenous gamma globulin (IVIG) to prevent RSV illness were studied in 23 high-risk infants in a phase I trial. IVIG with an RSV neutralizing antibody titer of 1:1,100 in 5% solution was given monthly over a 2- to 4-h period in a clinical setting during the RSV season. The first group (n = 7) received 500 mg/kg of body weight, the second group (n = 9) received 600 mg/kg, and the third group (n =7) received 750 mg/kg. Serum was drawn prior to infusion and 2, 14, and 30 days after infusion. Total immunoglobulin G and RSV A2 and RSV B neutralizing antibody levels were obtained after the first IVIG infusion. Two children developed mild reversible pulmonary edema (group receiving 600 mg/kg per dose), and one developed hives and wheezing during one infusion (group receiving 500 mg/kg per dose). Twelve children developed subsequent RSV infection during two RSV seasons (November to April) over a 2-year follow-up period; 9 of 12 developed infection during the infusion year. Eleven illnesses were mild; one child died of progressive RSV illness (group receiving 500 mg/kg per dose). A cumulative infusion effect was not observed. IVIG appears safe and feasible in an outpatient setting, and at 750 mg/kg per dose, a target RSV antibody level of greater than or equal to 1:100 was achieved.

Child, Preschool↗
PubMed1991

Respiratory syncytial virus infection in C57BL/6 mice: clearance of virus from the lungs with virus-specific cytotoxic T cells.

We describe respiratory syncytial virus (RSV)-specific cytotoxic T-cell (CTL) lines and clones developed from the spleens of C57BL/6 and BALB/c mice. Line 7 and clones derived from it were H-2Kb restricted, whereas line 12 had both Kb and Db components. Both lines, and all the clones except one, could lyse targets infected with either strain A or strain B RSV. Line 7 or 7-11E1 cells (8 x 10(6) to 10 x 10(6) given intravenously cleared RSV from the lungs of infected mice. There was no morbidity or mortality in any of the infected mice whether or not they received T cells. The C57BL/6 mouse is a useful model system in which to study the role of the CTL response in protective immunity to RSV. CTL lines and clones can mediate clearance of RSV from the lungs of normal mice without producing any associated morbidity.

Animals↗
PubMed1990

On the use of excision repair defective cells in the wing somatic mutation and recombination test in Drosophila melanogaster.

Ten chemical mutagens were tested in the wing somatic mutation and recombination test in Drosophila melanogaster. This assay makes use of genetic markers expressed on the wing of adult flies. Larvae which are trans-heterozygous for mwh (multiple wing hairs) and flr (flare) were fed with the compounds either acutely (2, 4, or 6 hr) or chronically (48 or 72 hr), or were treated by inhalation (1 hr). Genetic changes induced in the somatic cells of the wing imaginal discs lead to the formation of mutant clones on the wing (mwh and/or flr). Single spots are produced by point mutation, chromosome breakage, and mitotic recombination; twin spots are produced exclusively by mitotic recombination. All 10 mutagens belonging to different chemical classes were clearly positive in this assay. However, the choice of the optimal treatment conditions (concentration of compound, duration of treatment, age of larvae at treatment) is essential. Eight of the compounds were also tested in excision repair defective cells by introducing the mei-9L1 mutation into the test system. This seems not to improve the detection capacity of the assay, mainly because only small spots are found in excision repair defective wings. In addition, the frequencies of spots in these wings are enhanced four to five times, which makes the scoring more tedious. For these and other practical reasons the use of this specific cross is not recommended in the wing spot test for routine screening purposes.

Animals↗