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Biomedical subjects

D McDonald

Publications and source records attributed to D McDonald.

At least 109 records · Page 6Linked to original sources
PubMed1987

Postpartum sit-ups.

Explore the source record for details and available documents.

Abdominal Muscles↗
PubMed1987

Factor structure of Calhoun's Youth Suicide Scale.

To assess the factor structure of Calhoun's Youth Suicide Scale (YSS), 191 consenting undergraduates in one sample and 240 consenting undergraduates in a second sample wee given the YSS during class. From the second sample, 152 subjects also took the YSS a second time about 1 month later. In the first sample, three factors, which accounted for 50.0% of the variance, emerged. They were: How the Parents were Viewed (in terms of psychological disturbance, likability, and blame); Expected Responses to the Bereaved Family (terms of tension and sympathy); and Empathy with Parents (whether the newspaper was viewed as correct in reporting the cause of death, how long parents were expected to grieve, and whether parents were expected to be liked). In the second sample, the same three factors emerged (accounting for 55.5% of the variance), with the exception of one item on Factor 3: expecting to like the parents. Congruence coefficients between the three factors in the two samples were .98, .94, and .78, respectively. Reliability correlations on individual items ranged from a low of .30 to a high of .61. These results indicate that the YSS is valid, stable, and moderately reliable for assessing reactions to youth suicide; thus, it would be a viable instrument for use in future research on reactions to suicide.

Adaptation, Psychological↗
PubMed1986

Antibody response of mice to lactate dehydrogenase-elevating virus during infection and immunization with inactivated virus.

BALB/c and Swiss mice were infected with lactate dehydrogenase-elevating virus (LDV) or immunized with glutaraldehyde-inactivated or ether-extracted virus and their plasma was monitored for anti-LDV IgG and IgM levels by ELISA and indirect fluorescent antibody staining, for neutralizing antibodies, for sensitized antibody-virus complexes, for immune complexes, and for total plasma IgG and IgM. In infected mice, anti-LDV IgM was transiently formed during the first 2 weeks post infection (p.i.) but only at a low level. Anti-LDV IgG was produced in a biphasic manner with an initial peak at about 10 days p.i. and a secondary rise reaching a maximum level 30-80 days p.i. which was retained throughout the persistent phase of infection. The concomitant appearance of comparable levels of low molecular weight immune complexes suggests that most anti-LDV IgG was complexed with LDV proteins. Also, as early as 10 days p.i., infectious antibody-LDV complexes developed, which were neutralizable by rabbit anti-mouse IgG, whereas antibodies that neutralize the infectivity of exogenously added LDV appeared only 1-2 months p.i. Throughout infection, most of the anti-LDV IgG was directed to VP-3, the envelope glycoprotein of LDV, which was found to exist in at least 10 distinct forms ranging in molecular weight from 24 to 42 kDa. Anti-LDV IgG levels as high as those observed in infected mice developed in mice immunized with inactivated LDV. Antibodies to glutaraldehyde-inactivated LDV were also mainly directed to VP-3, but exhibited no neutralizing activity. The polyclonal B cell activation associated with a persistent LDV infection and the formation of immune complexes were not observed in mice immunized with inactivated virus.

Animals↗
PubMed1986

Selectivity of some ergot derivatives for 5-HT1 and 5-HT2 receptors of rat cerebral cortex.

The affinities of several ergot derivatives for 5-HT1 and 5-HT2 receptors were evaluated using [3H]5-HT and [3H]mianserin, and membranes prepared from rat frontal cortex. CQ 32-084, which had a Ki value against the 5-HT2 component of [3H]mianserin binding of 9 nM, had little effect on [3H]5-HT binding and was selective for the 5-HT2 receptor. Lisuride and LY-158A also displayed preferential affinity for the 5-HT2 receptor. Dihydroergocryptine, CM 29-712, lergotrile and LY-062 were more selective for the 5-HT1 receptor. Bromocriptine showed little selectivity for either subtype. Overall, the ergot derivatives displayed markedly different affinities and selectivities for central 5-HT receptors suggesting that their serotonergic actions should be considered when evaluating their pharmacological spectrum of activity.

Animals↗
PubMed1985

The impact of aging on luteinizing hormone (LH) and thyroid-stimulating hormone (TSH) in the rat brain.

Immunoreactive and bioactive luteinizing hormone (LH), thyroid-stimulating hormone (TSH) and growth hormone (GH) have been described by this and other laboratories to be present in discrete areas of the rodent and primate brain. In the present studies, LH and TSH concentrations in serum, pituitary, hypothalamus, brainstem, cerebellum, cerebral cortex and hippocampus were measured in male Sprague-Dawley rats at 2.5 months of age, when 11-12 months old and at 24 months of age. There was a significant decrease in hypothalamic TSH concentrations in the 11-12-month-old rats compared to younger animals (672 +/- 127 ng/mg vs 86 +/- 17 ng/mg, P less than 0.001). This was unaccompanied by any changes in TSH levels in serum, anterior pituitary, or in any of the extrahypothalamic brain areas that were examined. In contrast, there was a significant 50% drop in LH concentrations in the anterior pituitary gland of 11-12-month-old animals when compared with young controls (72 +/- 58 micrograms/mg vs 137.2 +/- 27 micrograms/mg, P less than 0.05) without any noted change in serum or brain LH concentrations. Similar decreases in LH concentration were also seen in the anterior pituitary glands of two-year-old animals. These discordant profiles between pituitary and brain LH and TSH provide additional circumstantial evidence that these brain peptides do not represent contaminants from the anterior pituitary. Further, these significant changes in TSH and LH concentrations that develop with aging may implicate these particular peptides in the development of certain features of senescence.

Aging↗
PubMed1985

Prolactin levels in pregnancy: comparison of normal subjects with patients having micro- or macroadenomas after early bromocriptine withdrawal.

14 previously infertile patients, 11 with radiologically abnormal fossae, and a mean prolactin level of 761 ng/ml (range 49-4,500 ng/ml) conceived on 19 occasions during bromocriptine treatment. So far, 15 healthy infants have been delivered. Treatment was withdrawn soon after conception and the subsequent prolactin changes compared with those of 44 normal subjects. Prolactin levels returned to pretreatment values in 7, but stayed within our normal range (less than 350 ng/ml) in the 6 remaining patients studied. No patient developed signs or symptoms of tumor enlargement. 2 patients, 1 of them with the largest tumor, have now normal prolactin levels and can be considered as cured. Bromocriptine treatment can restore fertility and be safely withdrawn during pregnancy even in patients presenting with large tumors. Nevertheless, patients should be carefully monitored and treatment with bromocriptine re-introduced if necessary.

Adenoma↗
PubMed1985

Attention to television: intrastimulus effects of movement and scene changes on alpha variation over time.

Central and occipital EEG alpha were used as an on-line measure of momentary changes in covert attention during television viewing. Alpha was recorded during nine 30-second commercials shown embedded in a half-hour situation comedy. Two time series were constructed for data analysis. A stimulus series consisted of codes representing the presence or absence of scene changes or person and object movement for each half-second interval of the commercials. The alpha series consisted of median alpha scores for each half-second interval, aggregated across 26 subjects. The alpha series was regressed on the movement and scene change series, both of which produced significant increments in R, even after autocorrelational effects inherent in the alpha series were removed. As a validity check on the attentional interpretation of alpha, it was shown that mean alpha for each commercial was significantly (negatively) correlated with recall and recognition of commercial contents. The results are discussed in terms of their implications for further use of continuously-recorded alpha in research on factors that influence attention to television.

Adult↗
PubMed1984

Release of immunoreactive luteinizing hormone (LH) from rat hypothalamus-pars tuberalis explants.

A luteinizing hormone (LH)-like molecule has been described in the rodent central nervous system and has been shown to have immunologic, chromatographic, and biologic activity similar to that of pituitary LH. In this communication we report that a depolarizing stimulus, high potassium concentration in the presence of calcium, causes in vitro release of LH from hypothalamic explants containing the pars tuberalis. Release from other brain areas containing LH was not seen nor was release of LH, in vitro, significantly provoked from dorsal segments of the hypothalamus, thus suggesting that most, if not all, of the releasable LH from intact hypothalamic explants may come from cells of the pars tuberalis.

Animals↗
PubMed1984

Binding and function of serotonin 2 receptors following chronic administration of imipramine.

Experiments were undertaken to determine whether alterations in the binding of 5-HT2 receptors in the cerebral cortex of rat brain, induced by antidepressant drugs, are related to behavioral changes observed in response to the administration of a precursor of serotonin. Chronic (5 days), but not acute, administration of an imipramine-yohimbine combination resulted in a significant decrease in the binding of 5-HT2 receptors in the frontal cortex and wet-dog shakes induced by 5-hydroxytryptophan (5-HTP). The decrease in the binding to 5-HT2 receptors was due entirely to a change in the concentration of binding sites with no modification in receptor affinity. The behavioral alteration resulted from a decrease in the maximal response to 5-HTP. Further experiments revealed that chronic (5 days) administration of imipramine alone altered the behavioral response to 5-HTP without changing the binding of 5-HT2 receptor binding and that changes in 5-HT2 binding in the cortex were not always accompanied by an alteration in the response to 5-HTP. These results suggest a lack of correlation between the drug-induced change in 5-HT2 binding in frontal cortex and the function of serotonin 2 receptors.

5-Hydroxytryptophan↗
PubMed1983

Genetic effects of 2-methoxyethanol and bis(2-methoxyethyl)ether.

2-Methoxyethanol and bis(2-methoxyethyl)ether were subjected to the following assays for genetic toxicity: Ames' test, unscheduled DNA synthesis (UDS) assay in human embryo fibroblasts, sex-linked recessive lethal (SLRL) test in Drosophila, dominant lethal test in male rats, bone marrow metaphase analysis in male and female rats, and the sperm abnormality test in mice. In vivo test animals were exposed to atmospheric concentrations of 25 or 500 ppm 2-methoxyethanol and 250 or 1000 ppm bis(2-methoxyethyl)ether. Point mutations in Ames' test and UDS in fibroblasts were not increased by either compound, while the SLRL test gave ambiguous results which deserve further investigation. Chromosomal aberration frequencies were not increased in rat bone marrow, but there was evidence from the dominant lethal tests that both compounds have profound effects upon male rat fertility during the meiotic phase. Pregnancy frequency was greatly reduced and preimplantation losses were large. In addition, there was evidence of postimplantation losses. Sperm abnormalities were increased in mice exposed to both compounds, but particularly bis(2-methoxyethyl)ether. These effects on male reproductive cells were confined to the higher concentrations of both compounds. It was concluded that the weak mutagenic and particularly the strong antifertility effects described here are important for the safety evaluation of these ethylene glycol ethers.

Animals↗
PubMed1983

Enzymic synthesis of steroid sulfates XVI. Specificity and regulation of human adrenal hydroxysteroid sulfotransferase.

Pure hydroxysteroid sulfotransferase (EC 2.8.2.2) of human adrenal glands possesses a wide substrate specificity towards steroids. This wide specificity has now been found to extend to simple alcohols; normal aliphatic alcohols from C3 onwards acting as substrates with C9 showing the highest rate. Increased rate was accompanied by a decrease in Km. In marked contrast to the sulfurylation of steroids such as dehydroepiandrosterone, which exhibit wave-like kinetics, the kinetics with simple alcohols were of the normal Michaelis-Menten type. By means of enzyme antibody and enzyme stability studies evidence was provided that one and the same enzyme was responsible for sulfurylation of hydroxyls on the 3- and 17- positions of steroids and simple alcohols. The data lend support to previous evidence that the enzyme controls the secretion of dehydroepiandrosterone sulfate via steroid-specific binding sites, enabling self-regulation in response to ACTH action.

Adrenal Glands↗
PubMed1983

Management of giant vesicovaginal and vesicourethrovaginal fistulas.

We herein report on 15 patients with giant vesicovaginal (7) and vesicourethrovaginal (8) fistulas repaired since July 1979. All fistulas were repaired by a suprapubic approach with or without a concomitant vaginal approach. All 7 patients with giant vesicovaginal fistulas underwent a standard racket incision of the bladder with excision of the fistula, closure of the vagina and bladder, and an omental interposition, and were cured. Four patients with giant vesicourethrovaginal fistulas had a similar successful closure but only 2 were cured of the incontinence, while 2 remained totally incontinent owing to failure of the bladder outlet sphincteric mechanism. The latter 2 patients were managed by a Tanagho bladder flap urethral reconstruction: 1 remained totally incontinent and finally underwent diversion, while 1 was improved but not cured totally. Four patients were managed by repair of the fistula simultaneously with a Tanagho bladder flap: 2 had no previous abdominal repairs and both achieved continence postoperatively, while 2 had numerous attempts at repair (including abdominal approaches) before referral and only 1 was cured. Giant vesicovaginal fistulas can be repaired successfully in almost all patients. Although vesicourethrovaginal fistulas can be closed as readily there is a high likelihood of sphincteric inadequacy in patients with extensive urethral involvement. A bladder flap urethral reconstruction is valuable in these patients, particularly in the absence of prior suprapubic procedures.

Female↗