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Biomedical subjects

J Davidson

Publications and source records attributed to J Davidson.

At least 181 records · Page 10Linked to original sources
PubMed1989

Seizures and bupropion: a review.

The relationship between seizure occurrence and use of bupropion was examined on the basis of manufacturer's reports. The observed incidence of seizures with bupropion doses of 450 mg/day or less ranged from 0.35%-0.44%, depending on the method of calculation. The cumulative 2-year risk of seizures in patients receiving the maximum recommended dose of 450 mg/day or less was 0.48%. The risk of seizure appears to be higher with bupropion doses above the recommended maximum, and predisposing factors were noted in over half of the 37 reported cases. Possible risk factors are presented and recommendations are given for the use of bupropion.

Adolescent↗
PubMed1988

Pyrogenic immunomodulators increase the level of prostaglandin E2 in the blood simultaneously with the onset of fever.

Blood prostaglandin E2 (PGE2) levels, estimated by radioimmunoassay, and body temperatures of conscious rabbits were measured simultaneously during fever in response to polyinosinic: polycytidylic acid, lipopolysaccharide and interleukin 1/endogenous pyrogen. The effects of the antipyretic agent ketoprofen on both parameters was also studied. Significant rises (in the order of 6- to 8-fold) in the PGE2 level were observed after injection of either of the three pyrogens and occurred simultaneously with the rise in temperature. Ketoprofen given after the onset of fever in response to the pyrogens produced an immediate defervescence and a simultaneous decrease in plasma PGE2. Ketoprofen given before the pyrogens prevented any rise in either body temperature or plasma PGE2 level. When animals were subjected to an environmental temperature of 34 degrees C a hyperthermia was observed without any change in the blood PGE2 level. These results suggest that an increase in the blood PGE2 level may contribute to the pathogenesis of fever.

Animals↗
PubMed1988

Complement C4B-null alleles in Felty's syndrome.

C4A and C4B allotypes were compared in 20 patients with Felty's syndrome (FS), 52 patients with rheumatoid arthritis (RA), and 55 control subjects. Nineteen of the FS patients had HLA-DR4. A C4B-null allele was more frequent in the patients with FS (60%) than in either the RA patients (15%) or the control subjects (26%). Only the differences between patients with FS and those with RA remained statistically significant when DR4 positive subjects were compared. The C4B null allele may identify individuals within the rheumatoid population who are at risk of developing particular systemic complications.

Alleles↗
PubMed1988

Irradiation-reduced human chromosome 21 hybrids.

Rodent-human somatic cell hybrids have been constructed which contain fragments of human chromosome 21 as their only human material. This was done by irradiating rodent-human somatic cell hybrids containing a complete chromosome 21 to fragment the genome and then rescuing human GAR synthetase and various amounts of flanking chromosome 21 DNA by fusing with GAR synthetase-deficient hamster cells and selecting for growth in purine-free medium. Four irradiation-reduction hybrids were produced by this method and contain the distal, proximal, and central portions of the long arm of human chromosome 21, all centered about GAR synthetase. These irradiation-reduction hybrids were used as a panel to regionally map single-copy and individual copies of repetitive sequences. Using these hybrids along with another independently constructed hybrid, the GAR synthetase gene was mapped distal to SOD-1 and proximal to CP21G1(D21S60). Of special interest is the regional mapping of the gene for the amyloid beta-protein distal to pPW236B(D21S11) and proximal to SOD-1.

Animals↗
PubMed1988

The Sambia "turnim-man": sociocultural and clinical aspects of gender formation in male pseudohermaphrodites with 5-alpha-reductase deficiency in Papua New Guinea.

Continuing controversy surrounding the Dominican Republic studies of 5-alpha-reductase deficiency and the development of gender identity in male pseudohermaphrodites concerns the roles of culture and biology in determining the ambiguity of gender socialization in an unsophisticated population. The present paper provides a cross-cultural perspective on these problems through description of anthropological and clinical data for a sample (N = 14) of subjects suffering from 5-alpha-reductase deficiency. Nine of these male pseudohermaphrodites were reared ambiguously as male and five as female. Female subjects changed from the female to male-identified role, but in circumstances of social trauma. The authors find ambiguity here related to the presence of a third sexual category available for sex-assignment and typing. Cultural valuation of the male role makes gender-switching from female to male pragmatically adaptive. The study concludes that social-experiential and cultural factors are significant in the formation of gender identity change in male pseudohermaphrodites with 5-alpha-reductase deficiency.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1988

A study of depressive typologies using grade of membership analysis.

Grade of Membership (GOM) analysis, a multivariate technique for studying disease, was used to explore depressive typology and relationships between depression and anxiety. One hundred and ninety patients with RDC diagnoses of major or minor depression were assessed by the Hamilton and SCL-90 symptom rating scales, the Newcastle diagnostic indices for endogenous depression and for anxiety and depression. Demographic, family and treatment response information were used as external validators. Five pure types provided the most satisfactory solution to these data. One group corresponded to classical melancholia, occurring in older, stable, in-patients, who lacked panic-phobic symptoms. All patients with agoraphobia fell into two distinct in-patient and out-patient groups, which differed from each other in several ways. In one group, a link was found between panic attacks, agitated melancholia and familial pure depression. The second group was less symptomatic and had more atypical vegetative symptoms. Two more groups comprised mildly symptomatic, hypochondriacal, depression, and a highly neurotic, obsessive, anxious, non-phobic depression, which was commonly related to a physical stressor.

Adolescent↗
PubMed1988

Tribulin in post-traumatic stress disorder.

Tribulin (endogenous monoamine oxidase inhibitor/benzodiazepine receptor binding inhibitor) output was measured in the urine of 18 patients with post-traumatic stress disorder (PTSD) and 13 controls. The level of the two inhibitory activities was highly significantly correlated in the group as a whole. There was no difference between output of either inhibitor in patients and controls. However, when the PTSD group was subdivided according to various psychometric ratings, a pattern of output did emerge. Levels of both inhibitory activities were higher in agitated compared with non-agitated subjects, and lower in extroverts compared with introverts. This finding supports the view that tribulin output is raised in conditions of greater arousal.

Arousal↗
PubMed1988

Phosphinic acid inhibitors of D-alanyl-D-alanine ligase.

We report the synthesis of a series of phosphinic acid dipeptide analogues, NH2CH(R1)PO(OH)CH2CH(R2)CO2H, related to DAla-DAla. The best of these compounds are potent, essentially irreversible inhibitors of DAla-DAla ligase, and their preferred stereochemistry was shown by chiral synthesis of (1(S)-aminoethyl)(2(R)-carboxy-1-n-propyl)phosphinic acid, 12b, and by X-ray crystallography of its derivative benzyl [1(S)-[(benzyloxycarbonyl)-amino]ethyl](2(R)-carbomethoxy-1-propyl) phosphinate, 13, to correspond to the stereochemical configuration of DAla-DAla at both centers. A mechanism for the inhibition of DAla-DAla ligase by these compounds is proposed to involve an ATP-dependent formation of phosphorylated inhibitor within the enzyme's active site. The antibacterial activities of these compounds are modest although their spectra include both Gram-positive and Gram-negative susceptible organisms. The best antibacterial activity was shown by (1(S)-aminoethyl) [2-carboxy-2(R)-(methylthio)-1-ethyl]phosphinic acid, 3e, whose MIC's range from 4-128 micrograms/mL on nine of a panel of 11 bacterial organisms. Combination of one of the more active phosphinic acids 12b with the alanine racemase inhibitor fluoro-D-alanine enhances the antibacterial spectrum of the latter on several strains of bacteria and inhibits fluoro-D-alanine's self-reversal, which normally occurs at concentrations several fold higher than its MIC level. This inhibition of fluoro-D-alanine self-reversal is consistent with an involvement of DAla-DAla ligase inhibition in the antibacterial activity of these compounds.

Adenosine Triphosphate↗
PubMed1988

Maternal narcotic abuse and the newborn.

In 50 infants born to women who continued to take heroin during all or part of their pregnancy the drug withdrawal symptoms were mild and were noted in 21 infants (42%). Only nine infants required treatment. Sudden infant death syndrome occurred in two infants at 4 and 6 months.

Adolescent↗
PubMed1988

Use of nebulised saline and nebulised terbutaline as an adjunct to chest physiotherapy.

To determine whether sputum clearance is increased by using nebulised saline or terbutaline as an adjunct to chest physiotherapy, a radioaerosol method (using technetium-99m labelled human albumin millimicrospheres) was employed in eight patients with stable bronchiectasis on four occasions, for comparison of sputum clearance with four different regimens. These were: control, with the patient resting in an upright position; chest physiotherapy, by the forced expiration technique with postural drainage; and chest physiotherapy following five minutes' inhalation of either nebulised normal saline or nebulised terbutaline 5 mg. Use of both nebulised saline and nebulised terbutaline immediately before chest physiotherapy gave a significantly greater yield of sputum than did physiotherapy alone, and terbutaline also significantly increased radioaerosol clearance from the whole lung and from regions of interest. The mechanism is unclear, but this method may provide a simple way of increasing the efficacy of conventional chest physiotherapy.

Adult↗
PubMed1988

Glomus vagale tumors.

We present a case of a multicentric chemodectoma, with the unusual combination of a glomus vagale and a glomus tympanicum tumor. Multicentricity was suspected before selective carotid arteriography. Our patient, although asymptomatic, had elevated levels of urinary catecholamines preoperatively, which returned to normal postoperatively, suggesting biochemical activity of the tumor. Intraoperative hemostasis was assisted by the use of preoperative selective embolization of the tumor mass and the peripheral location of the injected Ivalon was confirmed histologically. The vagus nerve was anatomically spared and complete function was restored within 10 months. The asymptomatic small glomus tympanicum tumor was treated with embolization alone, as the patient chose to defer treatment at this time, but only time will reveal the effectiveness of this method of management.

Adult↗
PubMed1988

The parathyroid adenoma: an imaging/surgical perspective.

The clinical picture of hyperparathyroidism has changed since the implementation of routine serum calcium testing, resulting in more asymptomatic patients undergoing early surgical exploration. Although operative complications (e.g., recurrent laryngeal nerve paralysis, hypocalcemia, etc.) are not prevalent, the risk can be minimized by minimizing tissue dissection. For this reason, we feel that preoperative tumor localization is of great importance. We report our imaging results of parathyroid adenomas, utilizing ultrasonography, technetium-thallium subtraction scanning, digital subtraction angiography and magnetic resonance imaging. We also present an imaging protocol which, we have found, maximizes preoperative identification of these tumors.

Adenoma↗