Biomedical subjects
J M McKenzie
Publications and source records attributed to J M McKenzie.
Interactions of stress and endocrine status on rat peripheral lymphocyte responsiveness to phytomitogens.
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Selenium deficiency in total parenteral nutrition.
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Content of zinc in serum, urine, hair, and toenails of New Zealand adults.
The content of zinc in samples of serum, hair, and toenails and in a 24 hr urine from groups of the New Zealand population was investigated. The 110 normal healthy adults were mainly male and female students; the female students had a higher serum zinc and hair zinc concentration but a lower urinary zinc excretion than did the male students. The range in values within the normal groups was wide. No strong relationship was found with linear regression analysis or with multiple regression analysis of the data for the male or the female students. Other groups studied were oyster openers with a higher dietary intake of zinc from oysters, industrial workers exposed to zinc in their occupations, and hospital patients with leg ulcers or various dermatoses and with a potentially low zinc status. Only external exposure to zinc from an industrial source (galvanizing) or from the use of zinc-based creams increased the zinc concentration in the samples measured, and then only in hair and toenails. The hospital patients did not appear to have a lower zinc status comparable with adults from other countries. It was concluded that the measurement of zinc in serum, urine, hair, and toenails did not provide a sensitive indication of zinc status.
The cytochemical bioassay for thyroid -stimulating antibody of Graves' disease: further experience.
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Episodic and TRH induced growth hormone release in primary hypothyroidism of man and rat.
In 27 hypothyroid subjects studied over 20 to 120 minutes, the concentration of serum growth hormone (GH) was variable with the amplitude and frequency of the secretory patterns similar to those reported by others for normal individuals. Serum GH, after the administration of thyrotropin releasing hormone (TRH) did not differ from values observed as spontaneous surges, in contrast to a consistent increase in thyrotropin and prolactin. Episodic secretion of GH persisted in thyroidectomized rats and did not differ significantly from that present in intact controls. It is concluded that episodic GH secretion is not abolished in primary hypothyroidism and that TRH is not a constant GH secretagogue in human subjects with hypothyroidism.
Effects of altitude and two decongestant-antihistamine preparations on physiological functions and performance.
Fourteen men were studied to determine the combined effects of two altitudes--388 and 3,810 m or 1,274 and 12,500 ft--and three preparations--lactose placebo, Compound A (Actified, and Compound B (Dristan). Subjects reported least attentiveness with A and greatest with placebo. Fatigue increased significantly with time while energy, interest, and attentiveness decreased. The Multiple Task Performance Battery (MTPB) showed no effects of altitude, drugs, or time on overall performance; however, performance declined with time in several tasks, while problem solving improved. Subjects enjoyed the problem-solving tasks and may have given them preference as levels of interest declined. Though the MTPB overall composite scores did not change significantly, physiological parameters and subjective evaluations indicate that type of compound and time after ingestion are important. Declines in energy and attentiveness 2.5 h after ingestion could result in neglect of important--although routine--tasks. Hypoxia might enhance this effect and consequences might be worse in subjects whose medical conditions require these drugs.
Clinical, biochemical, and radiologic reversibility of hyperprolactinemic galactorrhea-amenorrhea and abnormal sella by thyroxine in a patient with primary hypothyroidism.
A case of primary hypothyroidism associated with postpartum galactorrhea-amenorrhea is reported. The configuration of the sella was compatible with pituitary adenoma, but prolactin dynamics did not support an autonomous secretory state. Replacement therapy with thyroxine led to complete reversal of clinical, radiologic, and biochemical abnormalities.
Pathogenesis of neonatal Graves' disease.
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Pituitary hyperthyroidism. Case report and review of the literature.
A 58 year old woman with an enlarged sella turcica was found to have hyperthyroidism with a supranormal concentration of serum thyrotropin. Transsphenoidal microsurgery resulted in the removal of a chromophobe adenoma comprised mainly of thyrotropes. Postoperatively, serum thyrotropin, thyroxine and triiodothyronine levels fell within normal limits, and the patient maintained normal thyroid and pituitary function.
Immune reactions in patients with Graves' disease.
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Humoral immunity in Graves' disease.
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The influence of normal human IgG and of thyroid-stimulating antibody (TSAb) on the binding of thyrotropin to thyroid plasma membranes.
The influence of serum IgG from normal and Graves' disease subjects on the binding of 125I-thyrotropin to isolated thyroid membranes was studied. IgG from either source inhibited binding in a concentration -dependent fashion. Human membranes were more sensitive to the human IgG than were bovine thyroid membranes and, when membranes were purified by discontinuous sucrose gradient centrifugation, they were more sensitive than were those less-purified, obtained by differential centrifugation. Using a Dixon plot, inhibition by normal IgG showed non-competitive kinetics. Fab fragments were more effective, on an equimolar basis, than was intact normal IgG, but were less potent when Graves' disease IgG was the parent molecule; this difference implies distinct modes of inhibition of thyrotropin-binding. The degree of inhibition by normal IgG was variable so that multiple control preparations are required to assess the additional effect characteristic of IgG from the subject with Graves' disease.
Zinc anc copper status of Polynesian residents in the Tokelau Islands.
Analyses for zinc and copper were performed in samples of serum, hair, toenails, and a 24-hr urine from Polynesian men and women resident in the Tokelau Islands. Selection of subjects was according to rank of systolic blood pressure obtained in a previous survey. The only difference in zinc anc copper values between the men and the women was a higher hair zinc concentration observed for the men. Rank of blood pressure had no influence on the measurements for zinc or copper, although within blood pressure ranks the men again had a higher hair zinc concentration than the women. Analysis of Tokelauan foods showed that most contained very low concentrations of zinc anc also low concentrations of copper. Octopus was one of the few rich sources of zinc and copper. Estimated daily dietary intakes (excluding water) were 4.5 mg Zn and 1.5 mg Cu. The reliability of measurements in serum, urine, hair, and toenails for assessing zinc and copper status is questioned.
Alteration of the zinc anc copper concentration of hair.
A washing and analytical procedure for the analysis of the zinc and copper concentrations of hair samples is described. The treatment of samples with nonionic detergent + EDTA wash removed the most adsorbed zinc anc copper from hair and was the washing procedure chosen for routine analyses. Beauty treatments had a variable effect on hair zinc and copper concentrations; the most drastic procedures were cold waving and bleaching; conditioner, hair spray, tint, and a permanent dye had a less drastic or no effect. Increasing distance of the hair from the scalp was associated with a regular increase in copper concentration and also increases in zinc concentration for most subjects.
Hypothyroidism-induced changes in triiodothyronine binding to nuclei and cytosol-binding proteins in rat liver.
A tracer dose of [125I]T3 was given iv to normal, thyroidectomized, and propylthiouracil-fed rats and the distribution of radioactivity in serum and liver fractions was studied over 1 h. Total liver homogenate and serum 125I were higher at all times in hypothyroid rats and, in all groups, showed a continuous fall over the period studied. Hepatic nuclear 125I was maximal at 20 min in all and was greater in hypothyroid rats; there was more 125I in the hepatic cytosol of normal rats than in that from either thyroidectomized or propylthiouracil-fed animals. Binding studies with [125I]T3 and purified hepatic neclear preparations in vitro indicated that both the association constant, Ka (1.08-9.0 x 10(9) M-1) and the capacity (500-600 pg/mg DNA) in thyroidectomized and goitrogen-treated rats were similar to those obtained with normal animals. Cytosol, on the other hand, showed a decrease in binding capacity without change in affinity in livers of hypothyroid rats. Analysis of binding data by Hill plots indicated the presence of both positive and negative cooperativity in binding of T3 by rat liver cytosol proteins. In the in vitro experiments, higher serum radioactivity alone could not account for increases in the hepatic nuclear 125I in the hypothyroid rats because cytosol 125I (presumably in dynamic exchange with both blood and nuclei) was less. Consequently, cytosol T3-binding proteins may regulate the free T3 concentration in the cell and, thus influence the distribution of the hormone in other cellular compartments.
Isoelectric focusing of thyroid-stimulating antibody of Graves' disease.
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Zoological specificity of human thyroid-stimulating antibody.
The zoological specificity of human thyroid-stimulating antibody (TSAb) that occurs in the blood in Graves' disease was examined by assessing its effect on the thyroid of the dog, guinea pig, calf, and mouse as well as that of man. With all but murine glands, thyroid stimulation was assayed by measuring the increase in the concentration of cAMP in the thyroid slices or fragments after 2 h of incubation in buffer containing TSAb. Effects on the thyroid of the mouse were monitored by the in vivo bioassay for LATS. Sera from 33 patients with Graves' disease were obtained and concentrates of TSAb were prepared by precipitation of IgG with 1.64 M (NH4)2SO4. These all stimulated the human thyroid, 13 were LATS-positive, and they variably affected the tissues of other species; of 27 tested, 14 stimulated the thyroid of the dog, 8 out of 23 stimulated the thyroid of the guinea pig, and 12 out of 16 stimulated the gland of the calf. The more potent the TSAb as assayed with human tissue, the more likely was it to stimulate other species of thyroid; however, frequent exceptions occurred. In a separate analysis of 35 LATS-positive preparations of TSAb, correlation between the responses in the LATS and human thyroid slice assays was statistically significant (P less than 0.001). The data are compatible with the view that stimulation by TSAb of nonhuman thyroids, including the murine as in the LATS bioassay, reflects cross-reaction of this immunoglobulin with an antigen that has sufficient similarity to the human molecule to be recognized by the human antibody.