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Biomedical subjects

J L Chen

Publications and source records attributed to J L Chen.

At least 145 records · Page 8Linked to original sources
PubMed1990

Repeated sympathetic stimuli elicit the decline and disappearance of prostaglandin modulation and an increase of vascular resistance in humans.

To investigate the role of prostaglandins I2 and E2 in modulating the vasoconstrictor response to sympathetic stimulation, repeated and proximate cold pressor tests were performed in 23 healthy young volunteers. Limb vascular resistance (blood flow measured by venous occlusion plethysmography), prostaglandin I2 (as 6-ketoprostaglandin F1 alpha) and prostaglandin E2 plasma levels (detected by radioimmunoassay), and plasma catecholamines (detected by high-performance liquid chromatography and electrochemical detection) were measured. A progressive increase in the duration of the vasoconstrictor response was observed with repetition of cold applications (p less than 0.001, by analysis of variance for trends). This increase was associated with a progressive decrease in cold-induced elevation of 6-ketoprostaglandin F1 alpha and prostaglandin E2 plasma levels until, after five stimulations, neither prostaglandin was detectable. The maximum detected concentration of norepinephrine did not significantly change, but its area under the curve in time showed a trend toward an increase. Epinephrine levels did not significantly change. The increase of vascular resistance was significantly correlated with the decrease of both prostaglandins (r = 0.93, p less than 0.05 for prostaglandin E2 and r = 0.89, p less than 0.05 for 6-ketoprostaglandin F1 alpha), whereas no significant correlations were found between variations of vascular resistance and catecholamines. Prostaglandin blockade induced by diclofenac sodium administration caused, from the first cold application, a pattern of the vasoconstrictor response and plasma prostaglandin and norepinephrine changes similar to that observed at the fifth cold application in untreated subjects, when prostaglandins are no longer detectable in plasma. We conclude that an increased vasoconstrictor response to sympathetic stimulation in humans may result from a diminished inhibitory influence of prostaglandins on adrenergic transmission.

Adult↗
PubMed1990

Nuclear 3,5,3'-triiodothyronine receptors (T3R) of circulating human lymphocytes in hyper- and hypothyroidism and nonthyroidal diseases.

The clinical implications of nuclear T3R alterations of circulating lymphocytes in hyperthyroidism, hypothyroidism and nonthyroidal diseases were investigated. Nuclear T3R in lymphocytes was determined by radio-ligand binding analysis. The results showed that in hyper- and hypothyroid patients the nuclear affinity (Ka) for T3 was similar to that of normal subjects. In hyperthyroidism nuclear T3 maximal binding capacity (MBC) was unaltered, whereas in hypothyroidism the MBC was significantly increased. In the patients with diabetes mellitus, chronic renal failure and hepatic cirrhosis, the nuclear T3R MBC of lymphocytes was about 1.5-1.6 times of the normal controls. It was concluded that there existed hormonal regulation of nuclear T3R, and up-regulation was seen in hypothyroidism and low T3 syndrome.

Diabetes Mellitus↗
PubMed1990

Pituitary abscess-A case report.

Two hundred and five cases of pituitary lesion were treated in Tri-Service General Hospital up to March 1989. A case of pituitary abscess was diagnosed during operation. The primary clinical manifestations are consequent upon the pituitary dysfunction and the mass effect of the pituitary abscess. A pre-operative diagnosis of pituitary abscess is usually very difficult. Transsphenoidal drainage with an appropriate antibiotic coverage may provide an optimistic prognosis.

Abscess↗
PubMed1990

[Change in serum growth hormone in aged men and effect of kidney-warming and yang-restoring drugs].

Basal and sleeping levels of serum growth hormone (GH) were measured in aged men and young men. GH levels after an intravenous bolus of growth hormone releasing hormone (1 microgram/kg) were also determined in healthy aged men with mild Kidney-Yang deficiency. The effect of Chinese herbs with Kidney-warming and Yang-restoring function was observed. The basal GH value in aged men was not significantly different when compared with young men, but the GH value during sleep evidently decreased (P less than 0.05). The response of GH to GRF was obviously decreased as compared with young people. The GH level following GRF stimulation was significantly different from that of young men. The Kidney-warming and Yang-restoring Chinese herbs could alleviate the symptoms of Kidney-Yang deficiency in aged men. The sleep value of GH and response of GH to GRF were increased after taking Chinese herbs. It suggested that the decrease of pituitary reserve might probably be the pathogenesis of Kidney deficiency. Together with the results of another animal experiments, the authors presumed that the Chinese herbs with Kidney-warming and Yang-restoring characteristics might effect through the increase of hypothalamic dopamine and the subsequent improvement of pituitary hormone reserve.

Aging↗
PubMed1989

The antihypertensive and renal activities of potassium canrenoate are associated with increased renal prostaglandin excretion.

1. In a double-blind, randomized, cross-over study the effects of potassium canrenoate administration (100 mg twice daily for 10 days orally) on renal prostaglandin synthesis (prostaglandin E2 and prostaglandin F2 alpha) were evaluated in 10 normotensive females and in 10 females with essential hypertension. 2. When compared with normotensive subjects, hypertensive patients in baseline conditions showed a reduced excretion of urinary prostaglandin E2 associated with an excessive prostaglandin F2 alpha production. 3. Potassium canrenoate significantly reduced mean blood pressure in hypertensive patients [from 118.9 +/- 8.7 mmHg (1.62 +/- 0.12 kPa) to a peak minimum value of 104.7 +/- 9.8 mmHg (1.42 +/- 0.13 kPa) on the seventh day of treatment; P less than 0.01 for the whole period] but not in control subjects [from 88 +/- 9.4 mmHg (1.20 +/- 0.13 kPa) to 84.3 +/- 8.3 mmHg (1.15 +/- 0.11 kPa) on the eighth day, NS] even though potassium canrenoate significantly increased sodium excretion in both groups. Renal prostaglandin excretion was affected differently in the two groups: in control subjects excretion of both prostaglandin E2 and prostaglandin F2 alpha was increased after drug administration, whereas in hypertensive patients only prostaglandin E2 excretion was enhanced.

Adult↗
PubMed1989

Haemodynamic and cerebrovascular responses to glycerol infusion in dogs.

1. The response of cerebral blood vessels to hyperosmolar agents in vivo remains controversial, and little is known about the effect of glycerol on cerebral vessels. In this study we investigated the cerebrovascular response to intravenous administration of glycerol (1 g/kg, infused over 25 min) in dogs under pentobarbital anaesthesia. 2. intracranial pressure, systemic arterial pressure, mean arterial blood pressure, serum osmolarity and packed cell volume were continuously monitored, and blood gases were checked frequently. Through a parietal cranial window, pial vessel diameter was measured by means of a surgical microscope and a video image-analyser. 3. Pial vessel diameter increased gradually with a maximum at 30 min after the beginning of glycerol infusion. The maximum increase in diameter in small (less than or equal to 100 microns) vessels was 14.3%, whereas that in large (greater than 100 microns) vessels was 10.3%. There was only a slight increase (less than 4%) in pial vessel diameter in vehicle-infused animals. The intracranial pressure decreased drastically after glycerol infusion, whereas the mean arterial blood pressure remained constant. There were correlations between the rise in serum osmolarity, fall in packed cell volume and vasodilatation, indicating that glycerol caused vasodilatation accompanied by plasma volume expansion. 4. Our data suggest that glycerol produces cerebral vasodilatation, which might be beneficial in cerebral ischaemia and vasospasm, in addition to its intracranial pressure-reducing effect on normal or oedematous brain. The degree of vasodilatation was not sufficient to affect the predominant intracranial pressure drop resulting from cerebral dehydration.

Animals↗
PubMed1989

[Influence of yang-restoring herb medicines upon metabolism of thyroid hormone in normal rats and a drug administration schedule].

Large dose of Yang-restoring herb medicines. (Radix Codonopsis Pilosulae, Astragalus membranaceus, Radix Aconiti Praeparata, Epimedium brevicornum, Cortex Cinnamomi and Herba Cistanchis) may exert an unfavorable effect on normal rats, i. e. natural weight gain reduced (P less than 0.01), serum T3 decreased (P less than 0.05), rT3, TRH levels raised (P less than 0.01) and TSH showed a raising tendency. Lower T3 and higher rT3 levels may be the effects of Yang-restoring herb medicines on the peripheral metabolism of thyroid hormones, i. e. more thyroxine was degraded to rT3 with little biological effect and less was transformed to T3 with strong hormonal effect. This unfavorable effect, however, can be avoided by Forward-Backward method. It was advised that large dose of Yang-restoring herb medicines could not be given to the organisms without symptoms of Yang-deficiency. If it were tried to do so, Forward-Backward method might be recommended.

Animals↗
PubMed1989

[On the types and distribution of crystals in medical plants].

Crystals in medical plants are classified into organic and inorganic according to their chemical components. This paper gives an account of the types, chemical compositions, appearances structures and existing ways in plant tissue and distribution patterns in plant kingdom of various kinds of crystals.

Calcium Oxalate↗
PubMed1989

[Effects of yang-restoring herb medicines on the levels of plasma corticosterone, testosterone and triiodothyronine].

It had been found that Yang-restoring herb medicines Radix Aconiti Praeparata (AP), Cortex Cinamomi(CC), Herba Cistanchis(HC) and Epimedium brevicorum (EB) reduced the cold-resistant potential of normal mice and disturbed the balance of thyroid hormones in normal rats. The aim of this study was to further investigate the effects of these four herb medicines on the levels of plasma corticosterone (B), testosterone (T) and triiodothyronine (T3) in rats by administering herbs together (mixed group) or individually. It was shown that all four Yang-restoring herbs tended to raise plasma B level and it was significant in HC, EB and mixed groups, especially in HC administered rats (P less than 0.001). Rise of plasma T level was seen in CC and mixed groups. All four herbs could decrease plasma T3 level and it was significant in AP, CC and mixed groups, particularly evident in AP administered rats (P less than 0.001). This may be one of the adaptating-protecting mechanisms of normal organism against the toxicity of AP. Combination of the four herb medicines did not result in the cumulation of effects of the given medicines, however, this did reflect the average effect of these four herbs, which showed a restraining and harmonious relationship in a Chinese medical prescription.

Animals↗
PubMed1989

[Changes of the sex hormones in female type II diabetics, coronary heart disease, essential hypertension and its relations with kidney deficiency, cardiovascular complications and efficacy of traditional Chinese medicine or qigong treatment].

In this study 31 normal child-bearing women, 62 postmenopausal women, 93 cases of female type II diabetes (18 child-bearing and 75 postmenopausal cases), 53 cases of coronary heart disease (11 child-bearing and 42 postmenopausal cases) and 38 cases of essential hypertension (8 child-bearing and 30 postmenopausal cases) were investigated. The average score of Kidney deficiency was 22.9-8. 5 before treatment with the combination of TCM and WM. With the treatment of TCM in diabetes and coronary heart disease and of Qigong in essential hypertension, the score decreased to 11.5-4. 4 (P less than 0.001). Serum/saliva estradiol (E2), the ratio of E2 to testosterone (T, E2/T) and progesterone (P) decreased before treatment of TCM or Qigong. After treatment E2 and P value increased; the ovarian endocrine function was improved; the special symptoms of the diseases relieved, fasting blood glucose levels in diabetics, the frequency and severity of angina pectoris in coronary heart disease and the blood pressure in essential hypertension significantly decreased respectively (P less than 0.01). The study suggested that there are certain relations between ovarian endocrine disfunction and Kidney deficiency. The more severe the "Kidney deficiency" was, the more significant the changes of sex hormone were.

Adult↗
PubMed1989

[Studies on the fine structure of Toxoplasma gondii tachyzoite].

Toxoplasma gondii tachyzoite was crescent-shaped. The pellicle of the parasite consisted of two membranes. The anterior end contained the polar ring and conoid, the former being the thickened inner membrane and the latter a cylindrical organelle which was made up of about 10 filaments arranged in an oblique row. The subpellicular microtubules numbering 22 originated at the polar ring and extended to the posterior end. The rhoptries extended from the conoid and terminated anterior to the nucleus with a narrow dense neck and an enlarged posterior portion with a glandular structure. The rhoptries perhaps had a secretory function and the conoid might be related to the invasion of the tachyzoite into the host cell.

Animals↗
PubMed1988

Measurement of basilar artery diameter in dogs: CT evaluation correlated with arteriography.

In this study we have used a computed tomographic (CT) method using profile analysis to measure the diameter of the basilar artery. In a search for a noninvasive and repeatable method to substitute for the traditional arteriography in the evaluation of the degree of cerebral vasospasm, we employed both CT and arteriography to measure the diameter of the basilar artery in eight adult mongrel dogs weighing between 7 and 12 kg. In three of these animals, assessments were made before and after subarachnoid hemorrhage (SAH) induced by injecting autologous arterial blood into the cistern magna. It was found that the basilar artery diameter as evaluated by CT was 47% larger than that measured by arteriography. However, there was a very good correlation (n = 63, r = 0.75, p less than 0.001) between the two methods. This paper presents a new model for the measurement of the basilar artery diameter, one which may also provide a safer method for the evaluation of vasospasm in humans.

Animals↗
PubMed1988

Computed tomography and pathologic correlations of thymic lesions.

Computed tomographic and pathologic correlations of the thymus gland were assessed in 69 patients. The sensitivity of computed tomography (CT) for undifferentiated thymic pathology is 87.1%; the specificity is 85.7%. The sensitivity of CT for neoplasm or mass is 97.1%, the specificity is 97.1%. The sensitivity of CT for lymphoid follicular hyperplasia (LFH) is 71.4%, the specificity is 97.6%. Therefore, a normal-sized thymus gland on CT does not exclude LFH. Completely preserved fat planes between thymic mass and adjacent structures on CT usually indicate a benign (noninvasive) neoplasm; completely absent fat planes usually indicate a malignant (invasive) neoplasm; partially preserved fat planes are indeterminate in assessing invasiveness. CT is also useful in showing recurrence or remnants of thymic tissue in patients who have had a previous thymectomy.

Adolescent↗
PubMed1988

Cancer incidence of workers exposed to dimethylformamide and/or acrylonitrile.

This study was to determine whether exposure to dimethylformamide (DMF) and acrylonitrile (ACN) separately or in combination, was associated with increased cancer incidence. Workers exposed to DMF and/or ACN were observed from 1956 through 1984 for cancer incidence. The workers exposed to DMF but not ACN showed significant excesses in incidence for buccal cavity and pharynx cancer and malignant melanoma. A significant excess of prostate cancer incidence was observed among workers exposed to DMF and ACN. No dose-response relationships were observed between DMF or ACN exposure and cancer incidence. The significant excesses in cancer incidence among employees exposed to DMF and/or ACN could be due to statistical chance or other factors, such as tobacco and alcohol consumption. Further studies are warranted.

Acrylonitrile↗
PubMed1988

Mortality study of workers exposed to dimethylformamide and/or acrylonitrile.

Workers exposed to dimethylformamide (DMF) and/or acrylonitrile (ACN) were observed from 1950 through 1982 for mortality. The wage-roll workers exposed to DMF showed significant excess in total deaths attributable mainly to ischemic heart disease and external causes when compared with rates from E. I. Du Pont de Nemours & Co. However, there were no significant excesses in mortality when expected numbers were based on US or local statistics. No dose-response relationships were observed between DMF or ACN exposure and mortality. The significant excesses in mortality among employees exposed to DMF and/or ACN could be due to statistical chance or life-style factors

Acrylonitrile↗