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Biomedical subjects

S V Smith

Publications and source records attributed to S V Smith.

50 records · Page 3Linked to original sources
PubMed1983

Simultaneous determinations of uterine blood flow and plasma concentrations of placental lactogen in late-pregnant goats.

Blood flow in the middle uterine artery was measured with electromagnetic blood flow probes, and placental lactogen in jugular and uterine venous plasma was estimated as total lactogenic activity using a radioreceptor assay. There was no circadian variation in uterine arterial blood flow in late pregnancy (Days 105-124) and the pattern of blood flow varied between goats. Blood flow was quite stable for periods of up to 40 min although at other times a rapid fall (by up to 90%) was followed by a gradual recovery. These spontaneous changes lasting up to 30 min could not be consistently related to postural or behavioural changes. Acute decreases of about the same duration could also be induced by administration of adrenaline. In the short-term there was no association between uterine blood flow and total lactogenic activity in the peripheral circulation during spontaneous or adrenaline-induced depression of blood flow. More limited short-term observations on total lactogenic activity in the uterine vein also failed to show a relationship with blood flow in the uterine artery.

Animals↗
PubMed1983

Study of prolactin levels in the ferret.

A radioimmunoassay for canine prolactin has been used to measure prolactin in the ferret. Serial dilutions of extracts of ferret pituitary glands and of ferret plasma yielded curves that were parallel with the canine prolactin standard curve. The sensitivity, accuracy, reproducibility and precision of the assay were within acceptable limits. Plasma prolactin levels increased after the administration of thyrotrophin releasing hormone (TRH) or chlorpromazine, but not after giving luteinizing hormone releasing hormone. Female ferrets, which were anoestrous, oestrous or spayed, and male ferrets had similar basal prolactin levels when sampled under sodium pentobarbitone anaesthesia. These basal levels were higher than in conscious males and the latter also showed a lesser response to TRH. Hypophysectomy significantly reduced basal prolactin levels in female ferrets by 2 h postoperatively and abolished the response to TRH.

Animals↗
PubMed1981

Effects of bromocriptine and occlusion of nipples on prolactin receptor and lactose synthetase activity in the mammary gland of the lactating rat.

The response of prolactin receptor and lactose synthetase to suppression of plasma concentrations of prolactin was examined in normal and occluded (teat-sealed) mammary glands of Sprague-Dawley rats, Rats, with mammary glands unilaterally occluded, were given bromocriptine (2.5 mg/kg per 12 h) between 5 and 8 post partum. Bromocriptine reduced plasma prolactin concentrations from 460.4 +/- 120.8 (mean +/- s.e.m.) to 2.56 +/- 0.89 ng/ml within 12h whilst concentrations in control rats were 553.4 +/- 110.25 ng/ml. Lactose synthetase activity declined rapidly, within 24h, in occluded glands of both groups but was maintained for 24 h in normal glands of bromocriptine-treated rats and decreased thereafter. Prolactin receptors also declined significantly within 24h in occluded glands. Desaturation of the prolactin receptor by bromocriptine treatment in vivo was compared with desaturation by exposure of membranes to MgCl2 in vitro. Both treatments enhanced prolactin binding but the increase after treatment with MgCl2 may have been partly artefactual since there was a selective loss of protein from the membranes. These results indicate that the prolactin receptor in rat mammary gland may be maintained after acute suppression of prolactin secretion.

Animals↗
PubMed1980

Placental lactogen in the goat in relation to stage of gestation, number of fetuses, metabolites, progesterone and time of day.

Placental lactogen has been measured in goats throughout pregnancy by radioreceptor assay of prolactin-like activity. Lactogenic activity, which is not prolactin, increased from less than 5 nmol/l in week 8 to 27 nmol/l by week 16. There was no further change until term. Plateau concentrations (week 16 to term) were highest in animals carrying triplets, 49.5 nmol/l. There were marked functuations in placental lactogen over a 24 h period. These short-term fluctuations were not related to changes in glucose, non-esterified fatty acids or, in two animals, progesterone. However, there was a negative correlation between mean concentrations of placental lactogen and glucose in plasma of 20 goats sampled over a 24 h period between weeks 15 and 20 of gestation. There was no difference in placental lactogen concentration from week 16 to term between goats in their first and second pregnancies although the normal period of increase in placental lactogen was delayed by some 3 weeks in goats in their second pregnancy. In hemimastectomized goats, hypophysectomy on day 60 did not affect placental lactogen but daily treatment with bromocriptine (5 mg/day) from day 60 to day 120 blocked the normal rise in concentration.

Animals↗
PubMed1977

Selection of medical specialties: preferences versus choices.

This study was undertaken to examine the extent to which there are differences between preferences and choices of specialty areas among medical students. A total of 350 medical students completed a questionnaire dealing with various aspects of a career in medicine, including specialty preference and choice decisions. The Intolerance of Ambiguity Scale was included as part of the questionnaire. Differences between specialty preference and choice were found for the total group as well as for male and female comparisons. Intolerance of ambiguity was found to be associated with the specialty decision process. Factors contribution to the differences were examined and recommendations for further research were discussed.

Career Choice↗
PubMed1973

Blood volume determination in the mouse.

1. The blood volume of the mouse has been measured using (59)Fe-labelled red cells to determine the red cell volume and (131)I-labelled human serum albumin to determine the plasma volume.2. Values for the blood volume of 95.0 +/- 1.5, 96.3 +/- 2.7 and 84.7 +/- 1.2 ml./kg body wt. were found for CSI female, CBA female and CBA male mice respectively.3. A marked discrepancy was observed between the venous (cardiac) haematocrit and the whole body haematocrit.4. The blood volume of the mouse must be determined from the red cell volume and the plasma volume, measured using appropriate labels, and not from the red cell volume or the plasma volume using the venous haematocrit.

Animals↗
PubMedDate not supplied

Rapid characterization of chemically-modified proteins by electrospray mass spectrometry.

Electrospray mass spectrometry (ESI-MS) has been used to examine monoclonal antibodies (MAbs), antibody fragments (Fab and Fc), modified fragments, and a range of other chemically-modified proteins as part of a study aimed at establishing ESI-MS as a method for the characterization of radioimmunoconjugates. This has been approached from two angles. Firstly, ESI-MS of complexes formed between chelators and other small molecules conjugated to hen egg white lysozyme (HEL) (14 kDa) demonstrate the considerable advantages of this powerful new technique compared with existing methods for the characterization of chemically-conjugated proteins. Molecular weights can be determined rapidly to within 0.01-0.05% and with good sensitivity (10-50 pmol total), thus providing specific structural information and opening the way for ESI-MS to be applied widely for the structural characterization of radioimmunoconjugates. Secondly, the conditions for ESI-MS of intact antibodies and antibody fragments have been examined in detail, and we have shown that the addition of up to 10 biotin molecules to the 50 kDa Fab fragment can be easily detected in ESI mass spectra, thus demonstrating the potential for the characterization of modified MAb fragments and metabolites. Finally, the strengths and limitations of ESI-MS of intact antibodies are discussed, and these results indicate that it may only be possible to detect average shifts in the mass of intact antibodies following modification.

Animals↗
PubMedDate not supplied

Laboratory analysis of cerebrospinal fluid.

OBJECTIVE: To review the physiology of cerebrospinal fluid (CSF), normal laboratory reference values, and key aspects of CSF sample collection, gross and microscopic examination, microbiologic testing, and chemical analysis. DATA SOURCES: Recent professional literature. STUDY SELECTION: Selected manually by the authors. DATA EXTRACTION: Articles manually by the authors. DATA SYNTHESIS: CSF is formed by a combined process of plasma ultrafiltration and active secretion. Mechanical and osmotic barriers exist between plasma and CSF and between CSF and brain. Lumbar puncture is the preferred technique for CSF sampling. Normal CSF should be clear, colorless, and free of clotted material. CSF can be examined for presence of microbes using stains. Additionally, the chemical composition of CSF can be examined; tests of interest include glucose, protein, lactate, enzymes, glutamine, specific amino acids, biogenic amines, and various drugs. CONCLUSION: Visual, microscopic, and chemical examination of CSF is essential to the clinical management of patients with CNS disease.

Cerebrospinal Fluid↗