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Biomedical subjects

C Lee

Publications and source records attributed to C Lee.

At least 1,009 records · Page 56Linked to original sources
PubMed1980

The action of dantrolene on transmitter mobilization at the rat neuromuscular junction.

Dantrolene sodium (20 microM) was found to decrease transmitter mobilization and the apparent available store of acetylcholine at frequencies of nerve stimulation of 50 and 100 Hz at the neuromuscular junction of the rat hemidiaphragm preparation treated with 2 microM (+)-tubocurarine. This effect of dantrolene sodium was not as marked at frequencies of nerve stimulation of 25 Hz or less, also no significant effect of the drug was observed on the amplitude of endplate potentials (EPPS) at any frequency of nerve stimulation. No effect of dantrolene sodium (20 microM) on mean miniature EPP amplitude or frequency was observed. It is suggested that the action of dantrolene sodium on mean EPP quantal content may be due to an action on stores of bound calcium within the motor nerve terminal. This effect of the drug is unlikely to be of physiological consequence in vivo, since it was only observed at high frequencies of nerve stimulation and did not cause a significant reduction of EPP amplitude during trains of stimuli.

Animals↗
PubMed1980

Energy-linked quinacrine fluorescence changes in submitochondrial particles from skeletal muscle mitochondria. Evidence for intramembrane H+ transfer as a primary reaction of energy coupling.

Submitochondrial particles obtained from skeletal muscle are open membrane fragments which show energy coupling yet cannot sustain transmembrane ion gradients. An energy-linked decrease in fluorescence emission of the fluorescent probe quinacrine is observed with skeletal muscle particles which is enhanced by the anion SCN-. This is essentially the same reaction observed with beef heart submitochondrial particles, in which the reaction is known to be a monitor of intramembrane H+ transfer. The results with skeletal muscle particles show that this intramembrane H+ transfer occurs in the absence of any electrochemical potential across the membrane. Further, it occurs independently of the direction of H+ exchange with the suspendingly medium, since energization of skeletal muscle submitochondrial particles is known to give H+ efflux into the medium, while energization of beef heart particles gives H+ uptake from the medium. We conclude that a primary reaction of energy coupling is intramembrane H+ transfer linked to electron transport but shielded from the suspending medium. Movements of H+ between membrane and medium are secondary reactions derived from the primary one, possibly linked by a series of intramembrane conformational changes comprising a sequential membrane Bohr effect.

Animals↗
PubMed1980

Thalifaurine and dehydrodiscretine, new quaternary protoberberines from Thalictrum fauriei.

Two new quaternary protoberberines, thalifaurine and dehydrodiscretine, were isolated from the ethanolic extract of Thalictrum fauriei Hayata. Based on spectral analysis and correlation with compounds of known structure, thalifaurine was shown to be 3-hydroxy-2-methoxy-10,11-methylenedioxyberbinium chloride and dehydrodiscretine was established as 3-hydroxy-2,20,11-trimethoxyberbinium chloride. The structural assignment was confirmed by synthesis of both compounds. Magnoflorine also was isolated and identified.

Alkaloids↗
PubMed1980

Biochemical profiles of prostatic fluid from normal and diseased prostate glands.

The attempt to identify changes in the biochemical composition of prostatic fluid that might accompany and characterize disease states in the prostate was stimulated by two assumptions based on observations. First, the composition of prostatic fluid was judged to be likely to reflect the metabolic status of at least the epithelial cells accurately. Secondly, the metabolic changes preceding or associated with the development of carcinoma in the prostate seemed likely to be diffuse rather than limited to the histologically abnormal prostatic cells. As a consequence of these assumptions, prostatic fluid obtained from the urethra by digital massage of the prostate was evaluated microscopically and subjected to numerous analytical procedures. Differences in lactate dehydrogenase (LDH) isoenzymes, complement C3, and transferrin concentrations in the prostatic fluid of men with histologically identified carcinoma (Ca) and benign prostatic hyperplasia (BPH) have been observed. The ratio of LDH-5/ LDH-1 was found to have a mean value of 5.94 +/- 0.25(S.E.) in 98 determinations on 83 patients with Ca, and 1.84 +/- 0.14 in 212 determinations on 142 patients with BPH with 10 or less white blood cells per high power field (WBC/hpf) on microscopic examination of the prostatic fluid. Fluid from 52 patients with BPH with greater than 10 WBC/hpf (84 determinations) had a mean ratio of 5.85 +/- 0.88 and from 286 patients with greater than 10 WBC/hpf without an established histologic diagnosis (460 determinations) of 3.12 +/- 0.21. Two hundred twenty-two men under 45 years of age (255 determinations) judged to have a normal prostate clinically had a mean ratio of 0.67 +/- 0.05. The mean transferrin concentration in 44 patients (51 determinations) with Ca was 47.03 +/- 3.76mg/100 ml, in 59 patients with BPH (90 determinations) was 12.97 +/- 1.20, in 23 patients with BPH with > 10 WBC/hpf in the prostatic fluid (38 determinations) was 14.93 +/- 2.19, in 87 patients with > 10 WBC/hpf (92 determinations) was 13.42 +/- 1.41, and in 33 patients less than 45 years of age with clinically normal prostates (33 determinations) was 7.45 +/- 1.08. The mean complement C3 concentration in 46 patients with Ca (57 determinations) was 17.48 +/- 1.60, in 58 patients with BPH (85 determinations) was 3.83 +/- 0.55, in 24 patients with BPH with > 10 WBC/hpf (39 determinations) was 5.87 +/- 0.68, in 93 patients with > 10 WBC/hpf (98 determinations) was 4.47 +/- 0.53, and in 34 patients less than 45 years of age (34 determinations) was 2.06 +/- 0.43. The mean ratio of LDH-5/LDH-1 was significantly greater for Ca than BPH with 10 or less WBC/hpf in the prostatic fluid. The mean concentrations of transferrin and complement C3 were significantly greater in Ca than in all other groups studied. No obvious relationship between stage of disease and these findings was observed. These observations support the suggestion that determination of prostatic fluid composition assists in identifying men with a high risk of cancer of the prostate.

Acid Phosphatase↗
PubMed1980

Constrictive effect of pancuronium on capacitance vessels.

The effects of pancuronium 0.08 mg kg-1, metocurine 0.4 mg kg-1 and tubocurarine 0.4 mg kg-1 on vascular tone were studied in 26 patients undergoing open heart surgery during total cardiopulmonary bypass. With a fixed rate of perfusion, arterial pressure is related directly to total peripheral resistance, while the volume of blood remaining in the extracorporeal reservoir is related inversely to vascular capacity, which depends primarily on venous tone. Pancuronium increased the reservoir volume (average of 780 +/- SEM 250 ml (P less than 0.01). We conclude that under certain circumstances pancuronium constricts capacitance vessels in man.

Adult↗
PubMed1980

4-Aminopyridine reversal of sympathetic ganglionic blockade in the anesthetized cat.

The effects of 4-aminopyridine on the blockades of transmission of the superior cervical ganglion produced by hexamethonium, d-tubocurarine, and polymyxin B were investigated in 15 anesthetized cats. Isometric contractions of the nictitating membrane resulting from pre- and postganglionic stimulation were quantified. A 75-85 per cent ganglionic blockade produced by hexamethonium, 3 mg/kg, or by d-tubocurarine, 1.0 to 1.2 mg/kg, was completely reversed by 4-aminopyridine, 1 mg/kg. After injection of 4-aminopyridine, the times required for the contractions of the nictitating membrane to increase from 25 to 75 per cent of control with preganglionic stimulation were 6 +/- 3 (mean +/- SEM) and 7 +/- 2 min for hexamethonium and d-tubocurarine, respectively. Both values are significantly (P less than 0.05) shorter than their respective control spontaneous recovery times of 26 +/- 8 and 25 +/- 7 min. Polymyxin B, 20-35 mg/kg, depressed the contractions of the nictitating membrane resulting from pre- and postganglionic stimulation by 84 +/- 2 and 66 +/- 10 per cent, respectively. 4-Aminopyridine, 1 mg/kg, lessened the polymyxin B-induced depression of the contractions of the nictitating membrane resulting from preganglionic stimulation to 50 +/- 13 per cent, but had less effect, 61 +/- 13 per cent, on the contractions resulting from postganglionic stimulation. It is concluded that 4-aminopyridine rapidly and completely reverses the sympathetic ganglion blackade produced by hexamethonium or d-tubocurarine, and is partially effective in the reversal of the autonomic effects of polymyxin B.

Aminopyridines↗
PubMed1980

The association of diabetes insipidus with hypoparathyroidism. Addison's disease and mucocutaneous candidiasis.

A case of central diabetes insipidus is reported in association with idiopathic hypoparathyroidism, adrenal failure and mucocutaneous candidiasis. The diabetes insipidus was recognised at the same time as the discovery of aldosterone and cortisol deficiency, and occurred several years after the initial onset of mucocutaneous candidiasis and hypocalcaemia. Control of the diabetes insipidus was achieved initially with nasal aqueous lysine vasopressin and later with desmopressin. The development of diabetes insipidus may be a further aspect of endocrine secretory failure associated with idiopathic hypoparathyroidism.

Addison Disease↗
PubMed1980

Levels of cyclic nucleotides in autotransplanted 7, 12-dimethylbenz[a]anthracene-induced rat mammary tumors during their growth and regression.

Previous studies indicated that autotransplanted 7, 12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumors were hormone-dependent and, if derived from a single primary tumor, many of their metabolic parameters varied little. Therefore, these tumors transplanted in multiple sites provided an opportunity for serial sampling of individual tumors for repeated biochemical evaluations. In the present study, primary mammary tumors induced by DMBA in female noninbred Sprague-Dawley rats were autotransplanted at six sites. When these grafts grew to an average size of 6 cm, the hosts were ovariectomized. Eighteen days later when all tumors were apparently regressing, a silastic tubing 2 cm long containing crystalline estradiol was implanted sc into each host for 14 days. Individual tumors were serially removed from each host before ovariectomy, after ovariectomy, and after estrogen replacement. Levels of cyclic AMP (cAMP) and cyclic GMP (cGMP) in these tumors were measured by radioimmunoassay. Results indicated that tumor regression was associated with an elevation of cAMP levels and that tumor growth was accompanied by a decline in cAMP. The level of cGMP did not correlate with either tumor growth or regression. Therefore, the concept that cAMP is a biologic regulator for tissue proliferation and regression may be applied to the present model of autotransplanted, DMBA-induced rat mammary tumors.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1980

Predetermination of dose requirement of pancuronium.

The neuromuscular sensitivity of 71 patients (A.S.A. class I or II) was tested by scoring on a scale from 1 to 6 the ability to lift the upper eyelid 2 minutes after pretreatment with 1 mg of pancuronium. Subsequently, each patient also received an additional "intubation dose" pancuronium (in milligrams) equal to the eye-opening test score (group I), or either 1 mg (group II) or 2 mg (group III) in excess. The resultant depression of the neurally evoked muscle response of the little finger was quantified by another score (the response score) which allowed for assessment of neuromuscular block beyond the limit of 100% depression of the twitch. The criteria for the response score, in the response score, in the order of increasing magnitude of block, were: (1) visible twitch responses to all 4 of the train-of-four stimulation remained; (2) part of the train-of-four twitches was eliminated; (3) all twitches were eliminated; (4) tetanus was eliminated; (5) post-tetanic twitch following a 5-second 50 Hz tetanus was also eliminated; and (6) not even the post-tetanic twitch became elicitable again in 30 minutes. It was found that 1 mg of pancuronium depressed the eye-opening score to 4.0 +/- 0.2, from 5.1 +/- 0.1 (mean +/- SEM, p < 0.01). Following the additional "intubation dose" of pancuronium, patients in group I had an average response score of 2.2 +/- 0.3, those in group II a score of 3.4 +/- 0.2, and those in group III, a score of 4.8 +/- 0.6. Each additional 1 mg of pancuronium (increasing from group I to III) linearly increased the average response score. In terms of frequency response, patients in group I had more than a 50% change of being scored 1, while those in group II had a greater than 50% chance of being scored 3, 4, or 5, and those in group III had more than a 50% chance of being scored 6. It is concluded that sensitivity to pancuronium can be quantified by the ptotic response to a 1-mg test dose of pancuronium, and that a sensitivity-adjusted additional "intubation dose" of pancuronium can be predetermined in individual patients.

Adult↗