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Biomedical subjects

R Hall

Publications and source records attributed to R Hall.

At least 199 records · Page 11Linked to original sources
PubMed1992

Effect of Pseudomonas aeruginosa rhamnolipids on mucociliary transport and ciliary beating.

Pseudomonas aeruginosa rhamnolipid causes ciliostasis and cell membrane damage to rabbit tissue, is a secretagogue in cats, and inhibits epithelial ion transport in sheep tissue. It could therefore perturb mucociliary clearance. We have investigated the effect of rhamnolipid on mucociliary transport in the anesthetized guinea pig and guinea pig and human respiratory epithelium in vitro. Application of rhamnolipid to the guinea pig tracheal mucosa reduced tracheal mucus velocity (TMV) in vivo in a dose-dependent manner: a 10-microgram bolus caused cessation of TMV without recovery; a 5-micrograms bolus reduced TMV over a period of 2 h by 22.6% (P = 0.037); a 2.5-microgram bolus caused no overall changes in TMV. The ultrastructure of guinea pig tracheal epithelium exposed to 10 micrograms of rhamnolipid in vivo was normal. Application of 1,000 micrograms/ml rhamnolipid had no effect on the ciliary beat frequency (CBF) of guinea pig tracheal rings in vitro after 30 min, but 250 micrograms/ml stopped ciliary beating after 3 h. Treatment with 100 micrograms/ml rhamnolipid caused immediate slowing of the CBF (P less than 0.01) of human nasal brushings (n = 7), which was maintained for 4 h. Mono- and dirhamnolipid had equivalent effects. The CBF of human nasal turbinate organ culture was also slowed by 100 micrograms/ml rhamnolipid, but only after 4 h (CBF test, 9.87 +/- 0.41 Hz; control, 11.48 +/- 0.27 Hz; P less than 0.05, n = 6), and there was subsequent recovery by 14 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Clinical pathology testing recommendations for nonclinical toxicity and safety studies. AACC-DACC/ASVCP Joint Task Force.

Clinical pathology testing in nonclinical toxicity and safety studies is an important part of safety assessment. In recent years, clinical laboratory testing has rapidly expanded and improved. Some government regulatory agencies provide guidelines for clinical pathology testing in nonclinical toxicity and safety studies. To improve these testing guidelines and the resultant safety assessments, the American Association for Clinical Chemistry's Division of Animal Clinical Chemistry and the American Society for Veterinary Clinical Pathology formed a joint committee to provide expert recommendations for clinical pathology testing of laboratory species involved in subchronic and chronic nonclinical toxicity and safety studies. These recommendations include technical recommendations on blood collection techniques and hematology, serum chemistry, and urinalysis tests.

Animals↗
PubMed1992

Reversible adrenocorticotropin deficiency due to probable autoimmune hypophysitis in a woman with postpartum thyroiditis.

The natural history and pathogenesis of lymphocytic hypophysitis remain poorly understood. We describe a 34-yr-old woman with postpartum thyroiditis and ACTH deficiency, studied at monthly intervals for 18 months after pregnancy. A significant titer of thyroid peroxidase autoantibodies was detected at 16 weeks gestation, and she was recruited into a prospective study of postpartum thyroid function. Four months postpartum she developed mild hyperthyroidism [free T4 (fT4), 27 pmol/L; TSH, less than 0.2 mU/L] and showed a rise in thyroid peroxidase and thyroglobulin autoantibodies. At 9 months postpartum, serum fT4 and fT3 levels were low normal (8.0 and 1.7 pmol/L, respectively), but TSH was not raised (0.4 mU/L). Subsequent investigation showed a low basal plasma cortisol level (28 nmol/L) in association with undetectable ACTH, and subnormal cortisol responses to depot Synacthen (535 nmol/L at 6 h) and hypoglycemia (peak, 145 nmol/L). FSH, LH, GH, and PRL function and computerized tomography of the pituitary were normal. Retrospective analysis of serum samples taken throughout the postpartum year showed developing hypocortisolemia between 3-9 months postpartum. Each sample was also tested for pituitary autoantibodies using a specific indirect immunofluorescent assay; none was detected. The ACTH deficiency recovered spontaneously, with normal cortisol responses to depot Synacthen (greater than 1380 at 6 h) and hypoglycemia (peak, 590) 14 and 18 months postpartum, respectively. This case illustrates that postpartum pituitary deficiencies are potentially reversible. The pattern of pituitary deficit and postpartum thyroiditis supported a diagnosis of autoimmune hypophysitis.

Adrenocorticotropic Hormone↗
PubMed1992

Postpartum thyroiditis: an organ specific syndrome which is not associated with a postpartum polyclonal B-cell activation.

Recent reports have detailed the presence of autoantibodies characteristic of non-organ specific autoimmune diseases in the serum of patients with autoimmune postpartum thyroiditis (PPT). These observations suggest that PPT could be part of a polyclonal B-cell activation postpartum. We have measured 4 non-organ specific autoantibodies (anti-DNA, anti-cardiolipin, anti-nuclear factor (ANF) and antibodies against extractable nuclear antigens (ENA)) together with autoantibodies against thyroglobulin and thyroid peroxidase in a group of PPT women at 4 time points during the first year postpartum (early, time of hyperthyroidism, time of hypothyroidism, late). Whilst 18/18 patients showed thyroid specific autoantibody changes there was only a low frequency of occurrence of the non-organ specific autoantibodies (ENA 2/18; ANF 1/18; anti-DNA 2/18; anti-dsDNA 0/18; anti-cardiolipin 0/18) and, when positive, the response was poor. We conclude that PPT is not associated with a polyclonal b-cell activation but is a postpartum rebound of a thyroid specific autoimmune phenomenon.

Antibodies, Antinuclear↗
PubMed1991

The pharmacokinetic behaviour of opioids administered during cardiac surgery.

Cardiac surgery with hypothermic cardiopulmonary bypass (CPB) is among the most commonly performed operations in Canada today. The potential effects of hypothermia and CPB on the disposition of certain opioids are reviewed. Reasons for prolongation of the elimination half-time of the opioids used during cardiac surgery are explored. The roles that age, hypothermia, protein binding and drug sequestration may play in changing opioid pharmacokinetic behaviour are examined and suggestions for future research are made.

Cardiac Surgical Procedures↗
PubMed1991

Ribosomal RNA sequences of Sarcocystis muris, Theileria annulata and Crypthecodinium cohnii reveal evolutionary relationships among apicomplexans, dinoflagellates, and ciliates.

Sarcocystis muris is a coccidium with a two-host life cycle involving the domestic cat and the mouse, Mus musculus. S. muris and Theileria annulata belong to the phylum Apicomplexa, but the latter organism is a tick-borne protozoon in the subclass Piroplasmea and causes tropical theileriosis in cattle. The small-subunit ribosomal RNA (16S-like rRNA) coding regions of these organisms as well as that of the free living dinoflagellate Crypthecodinium cohnii were amplified using polymerase chain reaction techniques and compared to 16S-like rRNA sequences from other eukaryotes. The 16S-like rRNA genes of S. muris and T. annulata are more similar to each other than either is to Plasmodium falciparum, the cause of malignant tertian malaria of humans or Plasmodium berghei, the agent of the commonly studied malaria of rodents. Evolutionary trees inferred from the rRNA sequence similarities support a close phylogenetic relationship between the Apicomplexa and Dinoflagellata as represented by Prorocentrum micans and C. cohnii. Apparently members of these related phyla arose from an ancestral stock that gave rise to the ciliated protozoa.

Animals↗
PubMed1991

Salt-split human skin substrate for the immunofluorescent screening of serum from patients with cicatricial pemphigoid and a new method of immunoprecipitation with IgA antibodies.

In patients with cicatricial pemphigoid, immunoglobulins (usually IgG) and complement are deposited within the dermoepidermal junction and are detected by direct immunofluorescent staining of perilesional mucous membrane and/or skin with fluorescein-labeled antibodies to human immunoglobulins. Although rare, some patients also have circulating low-titer, anti-basement membrane zone autoantibodies. In this study, we report 11 patients with the clinical, histologic, and immunologic criteria for cicatricial pemphigoid who had circulating anti-BMZ autoantibodies as demonstrated by positive indirect staining of a normal human skin that had been fractured through the dermoepidermal junction by prolonged incubation in a cold, 1 mol/L sodium chloride solution. On this salt-split human skin substrate, 9 of the 11 patients (82%) had autoantibodies that bound to the epidermal roof, one serum stained only the dermal floor, and one serum stained both sides of the separation. The predominant class of immunoglobulin in the patients' sera that bound to the substrate was IgA; IgA was the single immunoglobulin in 55% and was associated with IgG in 18%. IgG was the only immunoglobulin detected in 27% of the cases. No specific protein was detected by either Western immunoblot or a new IgA immunoprecipitation procedure.

Adult↗
PubMed1991

The intrauterine contraceptive device, "Multiload Cu 250": a regulatory problem.

Reports to the control agencies in Sweden and Australia of fractures of the intrauterine contraceptive device. Multiload Cu 250, led to a review of the safety of this device in these countries. The review revealed that fractures of the device had occurred in 15 other countries but in these countries only 5% of reports had been directed to the relevant national control authorities. The remainder either had been reported to the sponsor or had appeared in the published literature. An additional problem identified was one of thread rupture with the resultant difficulty in removal and the need for surgical intervention. It is apparent that the sponsor of the device was aware of the problems for some time since it made several significant changes to the device marketed in Sweden. These changes were made in 1983, without informing the Swedish agency and without its approval. These were 1622 Multiload Cu 250 devices returned to the Swedish agency for examination from 1988 to 1989. An analysis of 1516 of them found that the overall incidence of device fracture was 1:405 and of broken threads, 1:8. However, evidence suggests that the modifications conducted in 1983 and 1984 resulted in a device with very much less chance of fracture and/or ruptured threads on removal. Stress testing of 106 used devices suggested that the risk of fracture may increase with the length of time left in utero. Regulatory action in both Sweden and Australia involved changes in the information provided to physicians and patients. In Sweden, the additional step of withdrawing all earlier devices suspected of being associated with fracture and/or ruptured threads was taken.(ABSTRACT TRUNCATED AT 250 WORDS)

Australia↗
PubMed1991

Women's experiences of sexual abuse in childhood.

This study reports the results of questioning 1,253 women about experiences of sexual abuse during childhood. An incidence of 3.5% was identified; many of those affected reported benefit from the opportunity to discuss what had happened, an aspect which should be facilitated during routine consultations. The study identified a substantial burden on emotional health presenting into adult life. The wide range of places where abuse occurred and of relationships between the abusers/victims has important implications for educating children.

Adolescent↗
PubMed1991

Mental health services for deaf people: a need identified.

The unique problems of deaf people suffering from mental health conditions have long been recognised but have received inadequate attention in many parts of the country. In the absence of a specialist psychiatric service for deaf people in Wales a prevalence survey was conducted to estimate the numbers of deaf patients occupying long-stay mental health beds and to assess facilities available to them. A high prevalence of prelingual deafness was found in long-stay psychiatric inpatients, approximating to a relative risk ten times that in the general population. Throughout Wales there are approximately 100 patients with either prelingual or profound postlingual deafness resident in long-stay psychiatric and mental handicap beds. An inadequate provision of specialist support and equipment for all categories of deaf in-patients is demonstrated by the results of this study. Purchasers of mental health services must ensure that an acceptable quality of provision, including both access to a specialist psychiatric service and a supportive in-patient environment, is secured from providers.

Deafness↗
PubMed1991

Increased risk of cancer mortality after vagotomy for peptic ulcer: a preliminary analysis.

Patients (1,643) undergoing vagotomy for peptic ulcer at York District Hospital were traced through the Office of Populations Censuses and Surveys (OPCS) and cause of mortality obtained for the 577 who had died. Expected mortality for the cohort was calculated using a years at risk calculation in 5 year bands. There was an excess risk of mortality from cancer of all sites (1.5-fold), stomach (1.6-fold), colorectum (1.7-fold), biliary tract (4.1-fold) and lung (1.6-fold). There was no excess risk or mortality from cancer of the oesophagus, pancreas and female breast. The numbers of deaths have been too few and length of follow-up too short to investigate latency. The findings are consistent with the production of carcinogens as a result of the hypoacidity following vagotomy.

Biliary Tract Neoplasms↗
PubMed1991

Non-secretory adenomas of the pituitary treated by trans-ethmoidal sellotomy.

A consecutive series of 35 clinically non-secretory pituitary adenomas treated surgically by the transethmodial approach is presented. Mean age at presentation was 60 years, with a male-to-female ratio of 2:1. These tumours present later than hormone secreting tumours: 90% were over 2 cm in diameter at operation. Seventy-one per cent of patients had impaired vision and 89% had hypopituitarism. Surgical treatment relieved or significantly improved visual fields in 79% of patients with impaired vision. Ninety-one per cent required permanent hormone replacement. Mean follow-up was for 4.4 years. Five tumours recurred, causing recurrent visual symptoms. No tumours recurred in those patients treated with postoperative radiotherapy, but follow-up in this group was only for a mean of 2.7 years.

Adenoma↗