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Biomedical subjects

M Daniels

Publications and source records attributed to M Daniels.

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

Immune and neuroendocrine changes during bereavement.

Several studies document an association between bereavement and both suppressed lymphocyte responses to mitogen stimulation and impaired NK activity. In addition, women who are bereaved and have depressive symptoms show alterations in T cell subpopulations including a loss of T suppressor-cytotoxic cells and an increase in the ratio of T helper to T suppressor-cytotoxic cells. Although depressive symptoms may possibly mediate the immunologic changes during bereavement, the processes that modulate the immune system and link bereavement, changes in CNS activity, and immune function remain unknown. The increased secretion of cortisol in bereaved persons does not appear to mediate the suppression of NK activity, and further studies are necessary to explore the potential role of neuropeptides or catecholamines in altering immune function during bereavement.

Adrenal Cortex Hormones↗
PubMed1986

Group therapies for rheumatoid arthritis. A controlled study of two approaches.

An important unanswered question about rheumatoid arthritis (RA) is how the patient's psychological or emotional state relates to disease activity and functional status. No controlled studies of psychotherapeutic interventions in RA have been reported. To test the hypothesis that a psychosocial intervention would lead to improvement in functional status or disease activity, 57 RA patients were randomly assigned to 1 of 3 groups, which received: 1) conventional group psychotherapy; 2) group assertion/relaxation training; or 3) no treatment (control group). Patient and physician questionnaires collected at baseline, immediately after the interventions, and 12 months after baseline provided outcome data on functional status, social and psychological adaptation, psychological symptoms, and disease activity. There were few outcome measures for which either treatment resulted in significantly higher scores than were seen in controls, though more improvement did occur among patients who received conventional group psychotherapy.

Activities of Daily Living↗
PubMed1986

Growth hormone secreting pituitary adenomas are heterogeneous in cell culture and commonly secrete glycoprotein hormone alpha-subunit.

Cell culture methods were used to assess whether human pituitary adenomas secreting GH and associated with clinical acromegaly also secreted the structurally unrelated glycoprotein hormone alpha-subunit. Thirty-two tumours, together with peri-adenomatous tissue from two of them and three normal pituitaries were studied. Anterior pituitary hormones were measured by radioimmunoassay and included PRL, TSH, LH, FSH, and ACTH, as well as GH and alpha-subunit. Normal pituitary tissues secreted all hormones assayed. All 32 tumours secreted GH ranging from 241 to 5556 ng/2 X 10(5) cells/24 h and 12 (37.5%) secreted alpha-subunit in amounts which could not be accounted for by cross-reaction of other hormones or contamination by normal pituitary tissue, and which ranged from 10.3 to 73.5 ng/2 X 10(5) cells/24 h. Ten other tumours also secreted alpha-subunit but in very small amounts, not exceeding 1.8 ng/2 X 10(5) cells/24 h. PRL was secreted from 21 tumours (66%), and small amounts of other hormones, chiefly LH and TSH, were occasionally secreted from tumours. These cell culture studies would suggest that pituitary adenomas causing acromegaly are hormonally heterogeneous and that PRL and glycoprotein alpha-subunit are commonly detected in addition to GH.

Adenoma, Acidophil↗
PubMed1986

Methods of time sampling: A reappraisal of momentary time sampling and partial interval recording.

We compared the accuracy of momentary time sampling (MTS) and partial interval recording (PIR) in estimating both absolute behavioral levels and relative change. A computer randomly generated runs of pseudobehavior varying in duration and rate and simulated MTS and PIR of each run. Results indicated that when estimating absolute behavioral levels, duration rather than rate should be used as the dependent measure, and MTS is more accurate than PIR. In contrast, PIR is the more sensitive method for detecting relative changes in behavioral levels, although, at high rates, PIR tends to underestimate the degree of change.

Journal Article↗
PubMed1985

Effects of growth hormone-releasing factor (1-44) on growth hormone release from human somatotrophinomas in vitro: interaction with somatostatin, dopamine, vasoactive intestinal peptide and cycloheximide.

The effect of GH-releasing factor(1-44)(GRF) alone, or together with somatostatin (SRIF), dopamine (DA), vasoactive intestinal peptide (VIP) or cycloheximide was studied in a total of ten human somatotrophinomas using a static cell culture system. Growth hormone-releasing factor (2.0 X 10(-8) mol/l) significantly (P less than 0.05) stimulated GH release from nine out of ten tumours over 4-h incubations, and a dose-related effect (2.0 X 10(-10) -2.0 X 10(-8) mol/l) was observed in five tumours thus studied. Repeated GRF (2.0 X 10(-8) mol/l)-mediated GH release was seen during 96% (n = 25) of experiments performed on six tumours over 4 h and up to 27 days in culture. Growth hormone-releasing factor (2.0 X 10(-8) mol/l) also stimulated GH release from five out of seven somatotrophinomas during 60-min incubations. Somatostatin (6.1 X 10(-9) mol/l) completely inhibited GRF-induced GH secretion from four tumours studied over 4 h, but in each case there was significant (P less than 0.05) 'rebound' of GH release from cultures exposed to both GRF and SRIF during a subsequent recovery period. Dopamine suppressed basal GH release from two out of four tumours, but in each case had a greater inhibitory effect on GRF-mediated GH release. Vasoactive intestinal peptide directly stimulated GH release from two out of three tumours, and the effects were additive to maximal stimulatory doses of GRF. Cycloheximide significantly (P less than 0.01) enhanced GRF-stimulated release of GH during a 60-min incubation, but inhibited both basal and GRF-stimulated release over 4 and 8 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗
PubMed1984

Velocity of sarcomere shortening in rat cardiac muscle: relationship to force, sarcomere length, calcium and time.

The relation between force and velocity was determined in sixteen trabeculae of rat right ventricle as a function of time during a twitch, of sarcomere length and of external Ca2+ concentration, [Ca2+]o. The trabeculae were studied in modified Krebs-Henseleit solution at 25 degrees C. Force was measured with a semiconductor strain gauge. Sarcomere length was measured with a laser diffraction system. A servomotor system was used in which control could be switched between sarcomere length, muscle length and force. Force-velocity relations were derived from load clamps and from contractions in which sarcomere length was initially held constant followed by a quick release and slower release of the sarcomeres at controlled velocity. Force-velocity relations were fitted by Hill's equation (Hill, 1938), (Po-P) b = (P+a) V, where P = force, V = velocity, Po = isometric force in mN/mm2 and a and b are constants. For [Ca2+]o = 2.5 mM, with both interventions the values (mean +/- S.D.) were: b = 1.00 +/- 0.45 micron/s; a = 9.52 +/- 5.60 mN/mm2; Vo measured = 13.6 +/- 3.0 micron/s; Vo calculated = 13.4 +/- 3.4 micron/s; Po measured = 96.5 +/- 25.0 mN/mm2; Po calculated = 119.3 +/- 34.5 mN/mm2. Vo rose with [Ca2+]o to a maximum at [Ca2+]o = 1.2 mM when Po was about 50% of maximum, while Po rose with [Ca2+]o to a maximum at above 2.5 mM. Vo rose with time during the twitch to a maximum at 25 ms following onset of contraction; Po was then about 50% of the maximum that was obtained at 120 ms. Vo increased with sarcomere length from zero at a sarcomere length of 1.6 micron to a maximum at 1.85 micron. Between 1.85 micron and 2.3 micron, Vo was constant. At 1.85 micron, Po was about 60% of maximum Po. These results are compatible with the hypothesis that Vo is more sensitive than Po to the amount of Ca2+ bound to the contractile proteins, and that Vo reaches a maximal value with an amount of Ca2+ bound to the contractile proteins at which Po has obtained only about 50% of its maximal value.

Animals↗
PubMed1984

Social and structural factors affecting psychiatric consultation in the ambulatory medical setting.

The kinds of help primary care physicians requested from a psychiatric consultant in an ambulatory medical clinic are described. Based upon data from 173 encounters involving fifty-four physicians over a five and one-half month period, no single issue characterized a majority of encounters, and the nature of the help requested was diverse. Female physicians were more likely to initiate encounters that dealt with personal feelings about themselves or their patients. Male physicians were more likely to ask for assistance in evaluating patients. Whether or not a patient was seen as part of the consultation also significantly influenced the type of interaction that ensued as did the location of the interaction (hallway, room, or telephone) and whether or not the interaction was planned. Implications of these findings with regard to the training of primary care psychiatrists as well as the use of their services in ambulatory medical settings are explored.

Ambulatory Care↗
PubMed1983

Binding specificity of monoclonal antibodies towards fragments of human growth hormone produced by plasmin digestion.

To help define the immunological epitopes on human growth hormone (hGH), interaction of fragments of the hormone with 7 monoclonal antibodies (McAbs) was studied. Plasmin-digested hGH, containing two peptides (hGH1-134 and hGH141-191) joined by a disulphide bond, bound to each McAb with affinity similar to that of intact hGH. The purified C-terminal fragment, hGH141-191, showed low affinity for each McAb. The N-terminal fragment, hGH1-134, bound with quite high affinity to 2 McAbs (EB1 and EB3) but not to the other 5. We conclude that residues 1-134 of hGH contain the epitope to which McAbs EB1 and EB3 bind.

Amino Acids↗
PubMed1983

Synchrotron excitation of DNA fluorescence. Decay time evidence for excimer emission at room temperature.

The first lifetime measurements of DNA fluorescence are reported. Natural and synthetic DNA have been excited by 1.76 ns pulses of synchrotron ultraviolet radiation (270 nm) and the time profile of the fluorescence has been measured by synchronous single-photon counting. A post-pulse exponentially decaying emission has been observed with a lifetime of 2.9 +/- 0.4 ns for calf thymus DNA and 3.0 +/- 0.3 ns for poly(dA-T); this is most likely an excimer fluorescence.

Journal Article↗
PubMed1983

Effects of trifluoperazine on rat prolactin, growth hormone, thyroid stimulating hormone and adrenocorticotrophin secretion in vitro.

We have studied the effects of trifluoperazine, a proposed inhibitor of calmodulin directed cellular function, on adrenocorticotrophic hormone (ACTH), thyroid stimulating hormone (TSH), prolactin (Prl) and growth hormone (GH) secretion from primary cultures of rat adenohypophyseal cells. 5 X 10(-6)M and 10(-5)M trifluoperazine caused a significant (P less than 0.005) reversible dose-related decrease in basal Prl secretion but was less effective on basal GH secretion, significant reversible inhibition (P less than 0.005) occurring only with 10(-5)M. Trifluoperazine did not consistently alter basal ACTH or TSH secretion but did inhibit 10(-2)M theophylline stimulation of ACTH, Prl and GH secretion and 1.5 X 10(-7)M TRH stimulation of TSH and Prl secretion. Paradoxically 10(-5)M trifluoperazine enhanced theophylline stimulation of TSH secretion. Our results show trifluoperazine to have differential effects on Prl, GH, ACTH and TSH secretion, which are consistent with the known calcium dependence of pituitary hormone secretion and may suggest a role for calmodulin in this process.

Adrenocorticotropic Hormone↗