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Biomedical subjects

S Harvey

Publications and source records attributed to S Harvey.

At least 127 records · Page 7Linked to original sources
PubMed1992

Risk of human infections with Crimean-Congo hemorrhagic fever virus in a South African rural community.

Crimean-Congo hemorrhagic fever (CCHF) virus is widely distributed in wild and domestic mammals, birds, and ticks throughout many regions of Africa, Europe, and Asia. Interviews were conducted with 484 individuals from nine farms in the Republic of South Africa from which recent human CCHF cases had originated and with individuals from 27 farms without recognized cases. Serum samples were obtained from all consenting individuals. Blood was also drawn from 2,212 farm animals. Human infection with CCHF virus was uncommon (point prevalence 12.6/1,000). Antibody prevalence in humans on farms increased with age (P less than 0.001), and was correlated with handling lambs. Overall, a greater number of older animals were antibody positive than animals less than one year of age (P less than 0.001), but 12.7% of young animals on farms with human were antibody positive compared with 5.8% on those farms without human infection (P less than 0.05). Physical contact with ticks or tick bite was also found to be a risk factor, but contact with animal blood or fresh meat was not. The risk of CCHF virus infection in the community increased seven-fold following contact with a recognized CCHF case, even when other risk factors were taken into account (point prevalence rate 4.7%). In contrast, antibody prevalence was less than 1% (1 of 128) in the local hospital staff who had cared for patients with CCHF. Prevention is best achieved by education of the farming community and establishing and maintaining awareness in the hospital staff.

Adult↗
PubMed1991

Serum/saliva correlations for theophylline in asthmatics.

Theophylline levels in mixed saliva (both stimulated and unstimulated) were compared with total and free (unbound) serum theophylline levels in 28 asthmatic outpatients using theophylline regularly. Stimulated saliva predicted both total and unbound serum theophylline concentrations within +/- 1 microgram/mL in 62.5% and 92.9%, respectively, of the samples examined. In addition, the total serum levels could be used to predict unbound serum concentrations to within +/- 1 mg/L in 100% of the cases that were examined. These results indicate that saliva levels predict the unbound serum theophylline levels with greater accuracy and precision than they predict total serum theophylline levels. In addition, total serum levels can be used to reliably predict unbound serum levels. The use of mixed stimulated saliva is recommended as a reliable non-invasive method for monitoring unbound serum theophylline levels. The therapeutic range for saliva, which corresponds to the accepted total serum concentration range of 10-20 mg/L, is approximately 5.6-11.3 mg/L.

Administration, Oral↗
PubMed1991

Central somatostatinergic regulation of growth hormone secretion in dwarf chickens.

1. Basal circulating growth hormone (GH) concentrations in sex-linked-dwarf (SLD) chickens were unaffected by the intracerebroventricular (icv) injection of 10, 50 or 100 micrograms somatostatin (SRIF). 2. The GH response to systemic thyrotropin-releasing hormone (TRH; 10 micrograms/kg, iv) was, however, 'paradoxically' enhanced 20 min after icv SRIF administration. 3. A lower dose (1.0 micrograms) of SRIF had no effect on basal or TRH-induced GH release. 4. High-titre SRIF antisera (4 microliters) also had no acute effect on basal plasma GH concentrations, but augmented the GH response to TRH challenge. 5. SRIF would appear to act at central sites to modulate stimulated GH secretion in SLD chickens.

Animals↗
PubMed1991

Differential effects of T4 and T3 on TRH- and GRF-induced GH secretion in the domestic fowl.

The in vivo growth hormone (GH) response of immature domestic fowl to thyrotrophin-releasing hormone (TRH) and GH-releasing factor (GRF) was suppressed in birds fed diets supplemented (1 ppm) with triiodothyronine (T3) or given bolus intraperitoneal (ip) injections (100 micrograms/kg for 10 d) of T3. Supplementation (ppm) of the diet with T4 had no effect on secretagogue- induced GH release. Exogenous T3 or T4 suppressed basal, TRH- and GRF-induced GH release 2 h after daily ip administration (100 micrograms/kg for 10 d). 24 h after the last injection, only T3 was effective in inhibiting basal and stimulated GH secretion in vivo. The systemic administration of T3 was followed 2 h and 24 h later by a downregulation of pituitary TRH binding sites. T4 administration had no effect on pituitary TRH binding. When chicken pituitary glands were incubated in vitro, basal GH release was unaffected by the addition of 10(-9)-10(-5) M T3 or T4 to the incubation media. The in vitro GH response to TRH (10(-6) M) or GRF (10(-6) M) challenge was, however, suppressed in a dose-related manner by T3 but was unaffected by the coincubation of T4. These results demonstrate inhibitory effects of T3 and T4 on basal and secretagogue-induced GH secretion in fowl. T4 is less active than T3 and probably exerts some of its effects via T3-independent mechanisms.

Administration, Oral↗
PubMed1991

Post-transcriptional regulation of secretory protein production during the development of the guinea pig seminal vesicle.

To investigate the influence of androgens on secretory protein expression during the development of the guinea pig seminal vesicle epithelium, we examined the patterns of mRNA and protein accumulation during the first 2 wk after birth. Hybridization of total seminal vesicle RNA to cDNA probes revealed that the secretory protein genes were active as early as 5 days after birth. However, the accumulation of secretory proteins was barely detectable between Days 5 and 10, and could not be enhanced by treatment of neonatal animals with exogenous androgens. Secretory protein mRNA and protein levels both increased rapidly between Days 10 and 15. However, the 800-fold rise in protein levels between Days 5 and 15 greatly exceeded the magnitude of the increase in secretory protein mRNA that occurred during this interval. These data indicate that the rate of secretory protein accumulation in the guinea pig seminal vesicle is not determined strictly by the availability of secretory protein mRNA, and suggest that post-transcriptional mechanisms may contribute to the regulation of secretory protein accumulation in neonatal guinea pigs.

Aging↗
PubMed1991

Hemolytic and sphingomyelinase activities of Clostridium perfringens alpha-toxin are dependent on a domain homologous to that of an enzyme from the human arachidonic acid pathway.

The N-terminal domain of Clostridium perfringens alpha-toxin, homologous with the nontoxic phospholipase C of Bacillus cereus, was expressed in Escherichia coli and shown to retain all of the phosphatidylcholine hydrolyzing activity of the alpha-toxin, but not the sphingomyelinase, hemolytic, or lethal activities. The C-terminal domain of alpha-toxin showed sequence and predicted structural homologies with the N-terminal region of arachidonate 5-lipoxygenase, an enzyme from the human arachidonic acid pathway which plays a role in inflammatory and cardiovascular diseases in humans.

Amino Acid Sequence↗
PubMed1991

Hypo- and hypercalcemic peptides in fish pituitary glands.

Immunoreactive parathyroid hormone (irPTH), PTH-related peptide (PTHrp), and stanniocalcin-like peptides were detected in Coho salmon pituitary glands. The PTH, PTHrp, and stanniocalcin immunoreactivity of the salmon pituitary was separated by high-performance liquid chromatography purification into distinct peptide fractions that coeluted with pure preparations of these hormones. Stanniocalcin was localized by immunocytochemistry in the neurohypophysis and preoptic area of the platyfish brain, in areas in which irPTH has previously been detected in other teleosts. Although it is well established that the fish pituitary exerts hypercalcemic control over calcium metabolism, these results demonstrate the presence of hyper- and hypocalcemic peptides in teleost pituitary glands. The detection of PTHrp in the fish pituitary is the first report of its presence outside of mammalian species and suggests an early evolutionary divergence of PTH and PTHrp from an ancestral gene.

Animals↗
PubMed1991

Thyrotrophin-releasing hormone-induced growth hormone (GH) secretion in anaesthetized chickens: inhibition by GH-releasing factor at central sites.

Intracerebroventricular (i.c.v.) administration of GH-releasing factor (GRF) (at 1 or 10 micrograms) to anaesthetized immature (6- to 8-weeks-old) or adult (greater than 24-weeks-old) domestic fowl had no effect on basal GH concentrations in peripheral plasma, but suppressed (after 20 min) the acute GH response to exogenous (i.v.) thyrotrophin-releasing hormone (TRH) (1 micrograms/kg). The i.c.v. injection of GRF also reduced the content of somatostatin (SRIF) and dopamine (DA) in the hypothalamus, while increasing the concentration of the DA metabolite 3,4-dihydroxyphenyl acetic acid (DOPAC) and the DOPAC/DA ratio. The release of SRIF from hypothalamic tissue was stimulated in vitro by 100 nmol GRF/l. The inhibitory effect of i.c.v. GRF on TRH-induced GH secretion was blocked when it was simultaneously injected i.c.v. with SRIF antiserum. These results demonstrate central effects of GRF on avian hypothalamic function and suggest an inhibitory role for this peptide in GH regulation, possibly mediated through increased SRIF secretion.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

Growth hormone receptor gene: novel expression in pituitary tissue.

Specific hybridization of polyadenylated RNA, extracted from rat, rabbit and human pituitary glands with a 638 bp rabbit GH receptor (rGHR) cRNA was demonstrated by Northern analysis. In-situ hybridization of tissue sections with the probe demonstrated the localization of rGHR mRNA throughout the rat pituitary gland and its presence in the anterior lobe of the rabbit pituitary. Growth hormone binding sites on pituitary membranes were not, however, demonstrated by radioligand binding studies. Thus, although the GH receptor gene is expressed in pituitary tissue, functional GH receptors may not be inserted into pituitary plasma membranes.

Animals↗
PubMed1991

Thyroidal inhibition of chicken pituitary growth hormone: alterations in secretion and accumulation of newly synthesized hormone.

Hypothyroidism reduces GH synthesis and release in several mammalian species, in which thyroid hormone directly stimulates GH gene transcription. In contrast, hypothyroidism stimulates GH secretion in birds, in which thyroid hormone directly inhibits pituitary GH release. We have, therefore, investigated the effects of thyroid status on the accumulation of newly synthesized GH in the pituitaries of 8- to 10-week-old Leghorn cockerels in vitro and in vivo. The incorporation of [35S]methionine into immunoprecipitable GH ([35S] GH) was increased, over a 4-h incubation period, in glands from birds made hypothyroid by injections of methimazole (50 mg/kg day for 10 days) in comparison with glands from vehicle-injected controls. Treatment with tri-iodothyronine (T3, 100 micrograms/kg per day for 10 days) in vivo did not significantly alter the accumulation of [35S]GH in vitro but did block the release of [35S]GH in response to a GH secretagogue (thyrotrophin-releasing hormone; exposure to 280 nmol/l for 30 min) and reduced immunoassayable pituitary GH content. Pretreatment of glands from euthyroid birds with T3 (100 nmol/l) in vitro (for 20 h) reduced the basal accumulation of [35S]GH as well as that induced by another GH secretagogue (GH-releasing factor; 100 nmol/l) during a 6-h labelling period. These results show that, unlike the generally stimulatory action of thyroid hormone in mammals, in birds, T3 exerts a direct inhibitory effect on the accumulation of newly synthesized pituitary GH.

Animals↗
PubMed1991

Development of a mental health home care program.

Serving the mental health patient at home requires the coordination and teamwork of a psychiatrist, a mental health nurse, and family members, as well as an extensive planning process.

Community Mental Health Services↗
PubMed1990

Urokinase secretion from human colon carcinomas induced by endogenous diglycerides.

Colon tumor cells are more responsive to certain growth modulators in their local environment in vivo than are normal colonocytes. Examples of this class of compounds are the fecal diglycerides (DGs)(E. Friedman et al., Cancer Res., 49: 544-548, 1989), which may act as endogenous tumor promoters. At the concentration found in vivo, fecal DGs composed of oleic, myristic, and palmitic fatty acids induced mitogenesis of all classes of benign tumor cells and of half of the resected carcinomas tested in primary culture, but induced no detectable mitogenesis of normal colonocytes. Colon tumor cells also exhibit selective responses to these endogenous modulators as measured by another biological parameter, secretion of urokinase from carcinomas than from normal colonocytes. Fecal DGs also induced a 13-fold increase in urokinase mRNA synthesis in colon carcinoma cells and induced secretion of active urokinase from each of five resected carcinomas. Colon carcinomas, at both the primary site and metastatic to the liver, secreted the Mr 55,000 form of urokinase constitutively and secreted the same form upon treatment with fecal DGs. An increase in the steady-state level of urokinase secretion by saturated-chain DGs exhibited a strong dependency on the chain length of the fatty acid residues, those of 14 and 16 carbons having the greatest activity. Thus, fecal DGs composed of oleic, myristic, and palmitic acid residues induce two biological activities selectively in colon tumor cells, each of which would enhance tumor development. Selective mitogenesis would increase adenoma and carcinoma cell number relative to normal colonocyte number, and induction of the proteolytic enzyme urokinase would aid local invasion of the carcinoma within the bowel wall.

Blotting, Western↗
PubMed1990

Chemistry of male dominance in the house mouse, Mus domesticus.

Two terpenic constituents, E,E,-alpha-farnesene and E-beta-farnesene, were found to be elevated in dominant male urine when compared to subordinate or control males. These two urinary compounds were absent in the bladder urine of males; however, they were the most prominent constituents of the perputial gland's aliquots. The results of a two-choice preference test, conducted on ICR/Alb subordinate males, gave a strong indication that these two terpenic constituents introduced into the previously attractive stimulus significantly discouraged prolonged investigations by male mice. The compounds, whether present in the urine matrix or water, rendered the stimulus with a quality behaviorally similar to the urine of dominant males. It appears that they may be synonymous with the previously described aversion signal produced by dominant males. We suggest that these compounds may play a wide-ranging role in the territorial marking behavior of male mice.

Animals↗
PubMed1990

"Paradoxical" growth hormone secretion in acromegaly: an avian model?

Acromegaly is a pathological human condition resulting from an excess of growth hormone (GH) secretion in adults. The regulation of GH secretion in acromegalics is characterised by "paradoxical" GH responses to dynamic tests of pituitary GH function. Many of these "paradoxical" responses appear to be normal, physiological GH responses in aves. Comparative studies on the control of GH secretion in immature birds may therefore provide an experimental model for testing the effects of therapeutic agents of GH secretion.

Acromegaly↗
PubMed1990

Thyroid regulation of body temperature in anaesthetized chickens.

1. Anaesthesia caused marked decreases in the plasma concentrations of triiodothyronine (T3) and thyroxine (T4) and in the body temperature of young fowl. 2. Exogenous T4 or a thyroid hormone secretagogue (somatostatin antiserum), increased endogenous T3 and T4 concentrations and body temperature in conscious birds and prevented the body temperature decline in anaesthetized fowl. 3. These results provide further evidence for a role of T3 and T4 in temperature regulation in birds, particularly during anaesthesia.

Anesthesia↗
PubMed1990

Enhanced removal of Exxon Valdez spilled oil from Alaskan gravel by a microbial surfactant.

Remediation efforts for the oil spill from the Exxon Valdez tanker in Alaska have focused on the use of pressurized water at high temperature to remove oil from the beaches. We have tested a biological surfactant from Pseudomonas aeruginosa for its ability to remove oil from contaminated Alaskan gravel samples under various conditions, including concentration of the surfactant, time of contact, temperature of the wash, and presence or absence of xanthan gum. The results demonstrate the ability of the microbial surfactant to release oil to a significantly greater extent (2 to 3 times) than water alone, particularly at temperatures of 30 degrees C and above.

Accidents↗
PubMed1990

A rapid and specific high-performance liquid chromatographic assay for theophylline in biological fluids.

A rapid, specific high-performance liquid chromatographic analysis of theophylline in plasma, serum, and saliva is described. Proteins present in the biological samples are precipitated with 6% perchloric acid and the clear supernatant is chromatographed on a reversed-phase column. Only 100 microL of serum is required and concentrations as low as 0.07 micrograms/mL can be measured accurately. Other xanthines do not interfere in the assay. Within- and between-day variation is less than or equal to 2.2%. The method shows less bias and greater precision than the TDx (Abbott Diagnostics) procedure commonly used in clinical laboratories.

Chromatography, High Pressure Liquid↗