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Biomedical subjects

J Stuart

Publications and source records attributed to J Stuart.

At least 55 records · Page 3Linked to original sources
PubMed1996

A study of the prevalence of and risk factors for ear diseases and hearing loss in primary school children in Hat Yai, Thailand.

2,184 primary school children in Hat Yai Municipality, Southern Thailand were screened for ear diseases and hearing loss using screening audiometry, portable tympanometry and otoscopy to identify children with possible ear problems, 754 children failed the initial screen, 728 were retested and a group of 243 were referred for ENT examination and standard audiometry-tympanometry. Children with hearing loss and otitis media were thus identified. A questionnaire to identify possible risk factors was administered. The prevalence of otitis media in this population was found to be 3.25 per cent (AOM 0.69%, OME 1.14%, COM 1.74%). No risk factor identified as significant were found. Non-significant factors included sex, age, URI last month, father smoking, mother smoking and method of transport to school as an indication of social status. This study contrasts with a previous study in 1990 which showed a 3.5 per cent prevalence of COM.

Adolescent↗
PubMed1995

Functional haplodiploidy: a mechanism for the spread of insecticide resistance in an important international insect pest.

The coffee berry borer, Hypothenemus hampei, is the most important insect pest of coffee worldwide and has an unusual life history that ensures a high degree of inbreeding. Individual females lay a predominantly female brood within individual coffee berries and because males are flightless there is almost entirely full sib mating. We investigated the genetics associated with this interesting life history after the important discovery of resistance to the cyclodiene type insecticide endosulfan. Both the inheritance of the resistance phenotype and the resistance-associated point mutation in the gamma-aminobutyric acid receptor gene Rdl were examined. Consistent with haplodiploidy, males failed to express and transmit paternally derived resistance alleles. Furthermore, while cytological examination revealed that males are diploid, one set of chromosomes was condensed, and probably nonfunctional, in the somatic cells of all males examined. Moreover, although two sets of chromosomes were present in primary spermatocytes, the chromosomes failed to pair before the single meiotic division, and only one set was packaged in sperm. Thus, the coffee berry borer is "functionally" haplodiploid. Its genetics and life history may therefore represent an interesting intermediate step in the evolution of true haplodiploidy. The influence of this breeding system on the spread of insecticide resistance is discussed.

Alleles↗
PubMed1995

What mothers say about why poor children fall behind on immunizations. A summary of focus groups in North Carolina.

OBJECTIVES: To develop a more thorough understanding of the factors that impede poor parents' utilization of health care services for their children and to refine interventions to improve immunization rates. METHODS: We conducted focus group sessions with mothers whose children received care at the health departments in five North Carolina counties. Mothers were uninsured or were receiving Medicaid. A total of 50 women participated; group size varied from three to seven mothers. RESULTS: Socially disadvantaged mothers faced barriers at multiple points in the process of obtaining preventive care for their children. Organizational barriers, such as a lack of flexibility in scheduling and long waiting times, were exacerbated by personal barriers, such as a lack of reliable transportation, chaotic home environments, and employment conflicts. Lack of knowledge regarding the timing of childhood immunizations and misperceptions about the safety of immunizations were also important obstacles. Mothers made several suggestions, such as changes in scheduling, greater assistance with transportation, improved waiting facilities, and increased health education. CONCLUSIONS: Our study suggests that even with improved financing of well-child care, many important barriers to adequate immunization will remain. Many of the changes that mothers in our focus groups advocated are not related to insurance coverage and would be simple and inexpensive to implement. To help with these changes, we developed a checklist for use by health departments to determine which organizational barriers exist at their facility and suggest strategies to overcome the problems. Organizational, personal, and attitudinal barriers pose serious problems for socioeconomically disadvantaged families. To improve vaccination rates for children, new personnel and programs are probably less important than careful strategies to maximize existing resources.

Adolescent↗
PubMed1995

Importance of modified nucleosides to the structure and function of tRNAs.

Although a few modifications are found in DNA, 93 modified nucleosides have been found in the various RNAs. For the most part, the chemistry and structure that modified nucleosides, individually and in combination, uniquely contribute to DNA or RNA function have yet to be explained. However, there are ten physicochemical contributions that can be attributed to modified nucleosides. Of particular interest is the increasingly documented relationship between the presence of modified nucleosides in tRNAs, and the site and affinity of Mg2+ binding to RNA and its effect on function.

Binding Sites↗
PubMed1994

Additive in vitro effects of anti-sickling drugs.

To study the effect of anti-sickling drugs on cellular dehydration induced by entry of Ca, sickle cells were subjected to cyclical oxygenation-deoxygenation for 15 h in Ca-containing buffer. The consequential loss of cation (K) via the Ca-dependent K efflux (Gardos) channel caused cell dehydration and loss of deformability. Inhibition of a specific fraction of Ca entry by verapamil had no rheologically protective effect, whereas inhibition of the Gardos channel by clotrimazole or nitrendipine had a marked protective effect. When Gardos channel inhibition (by either clotrimazole or nitrendipine) was combined with stabilization of the oxy-conformation of sickle haemoglobin (by the substituted benzaldehyde 12C79), an additive protective rheological effect was achieved with 60-78% reduction in clogging rate of 5 microns diameter pores when compared with no drug. Therapeutic use of anti-sickling compounds in combination may achieve increased efficacy with lower toxicity.

Anemia, Sickle Cell↗
PubMed1994

Monitoring the acute phase response to vaso-occlusive crisis in sickle cell disease.

AIMS: To identify suitable acute phase proteins as objective markers of tissue ischaemia during painful vaso-occlusive crises in sickle cell disease. METHODS: The prodromal and established phases of 14 vaso-occlusive crises were studied longitudinally in 10 patients with sickle cell anaemia. Automated solid phase enzyme immunoassays were used to measure the fast responding acute phase proteins C-reactive protein and serum amyloid A protein. Slower responding glycoproteins (fibrinogen, orosomucoid, sialic acid and concanavalin-A binding) were measured in parallel. RESULTS: C-reactive protein and serum amyloid A protein increased early in crisis, sometimes within the early (prodromal) phase. Crises that resolved within 24 hours in hospital showed a minor and transient rise compared with crises that required treatment for four days or more. In eight crises treated by patients at home the acute phase response ranged from minor to a level consistent with extensive tissue ischaemia. CONCLUSIONS: Sensitive enzyme immunoassays for C-reactive protein and serum amyloid A protein are of potential value for monitoring the onset of tissue ischaemia in sickle cell crisis and for confirming subsequent resolution.

Acute-Phase Proteins↗
PubMed1994

Progesterone receptor detection in paraffin sections of human breast cancers by an immunoperoxidase technique incorporating microwave heating.

We sought to establish an easily interpretable and highly sensitive immunohistochemical method for detecting progesterone receptor protein in formalin-fixed, paraffin-embedded samples of breast carcinomas. Beginning with a conventional immunoperoxidase staining procedure, we incorporated microwave heating to compensate for the effects of conventional fixation and processing and then applied the method to 90 samples of primary breast carcinomas. We used the results of hormone binding assays as true values to establish the sensitivity, specificity, positive predictive value, and negative predictive value of the staining method. Our technique yielded good preservation of morphological detail and low nonspecific staining of background tissue. Comparisons of the results of staining and biochemical assays revealed that this progesterone receptor immunostaining procedure shows high sensitivity and acceptable specificity. We believe its performance characteristics make reliable study of small specimens and archival material possible.

Adult↗
PubMed1993

Serotonin and genetic differences in sensitivity and tolerance to ethanol hypothermia.

Mice have been selectively bred for genetic sensitivity (COLD) or insensitivity (HOT) to acute ethanol-induced hypothermia. COLD mice readily develop tolerance to the hypothermic effects of ethanol (EtOH) when it is chronically administered, while HOT mice do not. A number of studies have implicated serotonergic systems in both sensitivity and the development of tolerance to the hypothermic and ataxic effects of EtOH. In the experiments reported here, we administered the serotonin (5HT) neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) to HOT and COLD mice before the acute and chronic administration of equipotent doses of EtOH. 5,7-DHT lesions significantly reduced (by about 65%) whole brain levels of 5HT in both selected lines. This treatment reduced sensitivity to acute EtOH hypothermia in COLD, but not in HOT mice, and blocked the development of tolerance only in COLD mice. Metabolites of 5HT, norepinephrine, and dopamine were generally increased in hypothalamic and brain stem tissue after acute EtOH injection, but HOT and COLD mice were not differentially susceptible to these effects. These results suggest that genes affecting 5HT systems may mediate some of the differences in response to the hypothermic effects of EtOH characterizing HOT and COLD mice.

5,7-Dihydroxytryptamine↗
PubMed1993

Effect of transdermal oestradiol on the haemostatic balance of menopausal women.

OBJECTIVE: To determine the effect of transdermal oestrogen replacement therapy on the haemostatic balance of menopausal women. DESIGN: Open, parallel group, prospective study. SETTING: Three hospital-based menopause clinics. SUBJECTS: Fifty-two postmenopausal women receiving transdermal hormone replacement therapy (Estrapak 50) for 6 months. Comparison group of 48 untreated postmenopausal women studied in parallel. MAIN OUTCOME MEASURES: Changes in platelet number, plasma concentrations of coagulation factors and their natural inhibitors, fibrinolytic activity, and rheological parameters. RESULTS: Estrapak 50 had no significant thrombophilic effect on any of the outcome measures. CONCLUSION: The haemostatic balance and thus the risk of thrombosis would not appear to be upset by this dose of transdermal oestrogen.

Administration, Cutaneous↗
PubMed1993

Effect of patient age on tests of the acute-phase response.

Tests of the acute-phase response are used to screen for occult disease in the elderly, but there is little consensus as to their diagnostic value because of uncertainty as to the effect of age on reference ranges. We have therefore measured, as a function of age, the blood concentration of acute-phase proteins (C-reactive protein, alpha 1-acid glycoprotein, fibrinogen, albumin, and globulin) in parallel with three screening tests of the acute-phase response (erythrocyte sedimentation rate, plasma viscosity, and zeta sedimentation ratio). The study included 164 healthy individuals (age range, 25 to 84 years) plus 91 elderly ill but ambulant patients (age range, 65 to 84 years) from a family practitioner screening clinic. Reference ranges for the erythrocyte sedimentation rate, plasma viscosity, and zeta sedimentation ratio rose with age, with the erythrocyte sedimentation rate showing a particularly wide reference range. Healthy individuals aged 75 to 84 years, compared with those aged 65 to 74 years, showed a trend to a lower reference range for all three screening tests that may have reflected survival of the fittest individuals to the higher decade. Precise reference ranges are therefore required in the elderly; when these were used, the three screening tests showed a significant difference between elderly well and ill individuals.

Acute-Phase Proteins↗