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Biomedical subjects

K Yang

Publications and source records attributed to K Yang.

At least 307 records · Page 17Linked to original sources
PubMed1989

Fetal and adult sheep adrenal cortical cells contain glucocorticoid receptors.

Specific receptors for glucocorticoids were identified in the fetal and adult sheep adrenal cortex by a whole-cell binding assay using [3H]triamcinolone acetonide ([3H]TA) as the radiolabelled ligand. [3H]TA binding sites were saturable and of high affinity, with dissociation constant (Kd) of 2-3nM. Scatchard analysis revealed a single class of binding sites with a binding capacity (Bmax) of 207 and 5 fmol/10(6) cells for d100 fetuses and adults, respectively. By single point analyses at saturating [3H]TA concentration, we found that glucocorticoid receptors (GR) were present in the fetal adrenal cortex as early as d60. Highest concentrations were found at d100-110. GR decreased to d125, then increased to term (approx. d145) before declining again in newborn and adult animals. This demonstration of glucocorticoid receptors in ovine fetal adrenal cortical cells provides a mechanistic basis for the concept that glucocorticoids may act, perhaps in a paracrine or autocrine fashion, to influence adrenocorticotropin (ACTH)-induced activation of fetal adrenal function and the events leading to parturition.

Adrenal Cortex↗
PubMed1989

[Effect of the sympathetic nerve on the skeletal muscle blood flow at rest, during and after contraction].

The effects of the sympathetic nerve on the muscle blood flow were studied on the quadriceps muscles of anesthetized rabbits. The muscle blood flow was measured by heated thermocouple technique, electrolytic hydrogen clearance method and laser doppler flowmetry. There was significant correlation in the muscle blood flow measured by the above three methods. After blockage of the neuro-muscular junction with pancuronium bromide, the femoral nerve stimulations with pulse duration 0.1 msec, 6 V, at 2, 5 and 10 Hz caused no change in the muscle blood flow, while the stimulation with pulse duration 1 msec, 6 V, at 10 Hz caused reduction of the muscle blood flow. The higher the frequency of lumbar sympathetic trunk stimulation was, the lower the muscle blood flow became thus the longer the recovery time was. When femoral nerve and lumbar sympathetic trunk were stimulated simultaneously, increment of muscle blood flow during contraction became less prominent, especially, with a stimulation of 5 Hz, which caused a decrement of post-contraction hyperemia both in height and duration. These results suggest that sympathetic nerve activities have an influence on the muscle blood flow at rest, as well as during and after muscle contraction.

Animals↗
PubMed1988

Estrogen receptor and hormone responsiveness of medullary thyroid carcinoma cells in continuous culture.

We have examined the estrogen responsiveness and estrogen receptor in medullary thyroid carcinoma using a model of an established human cell line, TT. TT cells bind [3H]estradiol with high affinity. Scatchard analysis reveals a single class of binding site with a concentration of 173 fmol/10(6) cells and a dissociation constant of 2.1 x 10(-9) M, values which are comparable to those of a well established model cell line for estrogen responsiveness, MCF-7 human breast cancer cell line. Estradiol in physiological concentrations moderately stimulated TT cell proliferation, whereas in pharmacological concentrations it markedly inhibited cell growth. [3H]Thymidine incorporation into acid-insoluble material was also stimulated following a 5-day treatment with 5 x 10(-9) M estradiol. Tamoxifen at a concentration of 1 microM reduced cell proliferation by 43-48% after 5-7 days of treatment. The growth suppression induced by tamoxifen was reversed by addition of 10 nM estradiol. This is the first report of estrogen growth stimulation and tamoxifen growth inhibition of a tumor cell line derived from human medullary thyroid carcinoma.

Carcinoma↗
PubMed1988

Chronic intractable pain: an atypical presentation of multiple sclerosis.

Both acute paroxysmal pains and a variety of chronic pain syndromes have been described in multiple sclerosis. These usually occur in the setting of well-established disease. Although paroxysmal pain has been recognized as a rare first symptom in this disorder, presentation with severe, continuous dysesthesias of long duration has not been previously appreciated. We report the cases of three patients in whom refractory continuous pain signalled the onset of demyelinating disease. These observations further define the clinical spectrum of multiple sclerosis and have implications for the evaluation of patients with chronic neuropathic pains of unknown etiology.

Adult↗
PubMed1988

Ovarian steroid hormone involvement in endogenous opioid modulation of LH secretion in mature ewes during the breeding and non-breeding seasons.

The opioid antagonist WIN-44441-3 (WIN-3, Sterling-Winthrop) caused significant increases in LH secretion in ovariectomized ewes treated with progesterone but not in ovariectomized animals treated with oestradiol-17 beta. In the non-breeding season, plasma LH concentrations in ovariectomized ewes without steroid therapy, given oestradiol-17 beta or oestradiol-17 beta and progesterone together were not affected by treatment with WIN-3 on Day 6 after ovariectomy (there was a significant increase in LH as a result of WIN-3 treatment 13 days after ovariectomy in sheep given no steroid therapy). However, WIN-3 treatment of ovariectomized sheep given progesterone resulted in a significant increase in plasma LH. WIN-3 was ineffective when given to intact ewes treated with progesterone during the non-breeding season. With ovariectomized sheep during the breeding season there was again no response to WIN-3 at 6 days after ovariectomy in sheep given oestradiol-17 beta, but significant LH elevations in animals given no steroid, those given progesterone and those given progesterone + oestradiol-17 beta. The lack of an LH response to WIN-3 in ovariectomized sheep treated with oestradiol-17 beta did not result from a reduced pituitary response to GnRH since such animals responded normally to exogenous GnRH treatment. Overall, these results are consistent with the idea that, irrespective of the time of year, progesterone exerts negative feedback upon LH release at least in part through an opioidergic mechanism, whereas oestradiol-17 beta exerts negative feedback through steps unlikely to involve opioids. Progesterone can override the effect of oestradiol-17 beta during the breeding season only. Further, there appears to be a steroid-independent opioid involvement in LH suppression, operating at both times of year.

Animals↗
PubMed1987

Comparative data on cytophotometric DNA in malignant lesions of the esophagus in the Chinese and Japanese.

Cell DNA content was microspectrophotometrically determined in tissues of advanced esophageal carcinoma of 50 Chinese and 82 Japanese subjects. DNA distribution patterns were classified into Types I, II, III, and IV, according to the degree of dispersion and the peak value on the DNA histogram. The proportions of high ploidy (Types III and IV) in Chinese and Japanese patients were 68% and 81.7%, respectively. Overall 5-year survival rates of the Chinese and Japanese were 25.3% and 19.8%, respectively. Five-year survival rates of patients with Types II, III and IV were 45.7%, 23.8% and 0% in Chinese patients and 57.1%, 16.1%, and 0% in Japanese patients, respectively. Thus, differences in nationality were not related to the prognosis. The incidences of high ploidy group in those with an advanced esophageal carcinoma were high and were associated with a poor prognosis in both races. DNA distribution pattern of esophageal carcinoma reflected the outcome and malignant potential in the Chinese and the Japanese.

Carcinoma, Squamous Cell↗
PubMed1987

Strontium phosphate transfection of human cells in primary culture: stable expression of the simian virus 40 large-T-antigen gene in primary human bronchial epithelial cells.

Strontium ion formed DNA-phosphate precipitates analogous to those formed by calcium but lacking the lethal and differentiation-inducing effects of calcium on many epithelial cell types in primary culture. Human primary bronchial epithelial cells were transiently and stably transfected by using strontium phosphate; the frequency of stable transformation with a plasmid carrying the simian virus 40 large-T-antigen gene was greater than 10(-4).

Antigens, Viral, Tumor↗