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Biomedical subjects

B Sun

Publications and source records attributed to B Sun.

At least 307 records · Page 17Linked to original sources
PubMed1987

Anatomical analysis of the cause of skin necrosis of the great toe after transplantation of the great toe nail flap.

Necrosis of skin on the medial side of the great toe has been a significant complication of the great toe nail flap. To investigate the reason for this, a study of the blood supply of the medial side of the great toe was carried out on 55 feet with the injection of red latex into the arteries and on 13 vascular cast specimens. It was found that, after the blood vessels from the plantar and dorsal sides of the great toe are severed during the operation, the skin of the medial side of the great toe is mainly supplied by the medial vascular network at the head of the first metatarsal bone. It is clear that the blood supply from this network may sometimes be insufficient to nourish the skin. It is suggested that the operative incision should be changed so as to increase the blood supply to the medial vascular network which may decrease the incidence of skin necrosis.

Humans↗
PubMed1986

Endocrine aspects of human uterine sarcoma: a preliminary study.

The biologic effect of estrogen and progesterone in human uterine sarcoma is poorly understood in comparison to that of endometrial adenocarcinoma. In an attempt to elucidate the endocrine status of these tumors, we have investigated the ability of these tumors to synthesize estrogen by measuring the aromatase activity and studied the effect of aromatase inhibitors on the activity. In addition, the effect of estrogen and progesterone on aromatase activity and the growth pattern of these tumors were studied in cell culture and athymic mice systems. Aromatase activities in eight uterine sarcomas ranged from 0.7 to 37 fmol/hr X mg protein, which were within the range or higher than the activity found in normal proliferative endometrium (0.5 to 3 fmol/hr X mg of protein, means = 1.6, n = 10). These results indicate that uterine sarcomas are capable of producing estrogen. However, the enzyme activity showed no correlation with the morphology of tumors or the age of patients. Results from the kinetic studies of aromatase activity in one of the uterine sarcomas indicated that 19-nortestosterone, testolactone, and aminoglutethimide (the most effective one) inhibited aromatase activity. In addition, induction of aromatase activity in two uterine sarcomas was investigated in cell cultures. Progesterone caused an eightfold increase in activity in a sarcoma that was estrogen and progesterone receptor positive but had no effect in a tumor that was estrogen and progesterone receptor negative. The growth rate of two estrogen/progesterone receptor-negative uterine sarcomas was studied in cell culture and in athymic mice. Progestin, but not estrogen, reduced the growth rate in both systems; 30 nmol/L of estrogen had no effect on the growth rate. In summary, we have found that human uterine sarcoma is able to synthesize estrogen. Progesterone is able to induce the aromatase activity in estrogen/progesterone receptor-positive tumors, and progesterone also suppresses the tumor growth rate in estrogen/progesterone receptor-negative tumors. These results suggest that a select group of uterine sarcomas is sensitive to steroid hormone and that progesterone may be potentially beneficial for therapeutic treatment of select uterine sarcomas.

Adult↗
PubMed1986

Modulation of aromatase activity in human endometrial stromal cells by steroids, tamoxifen and RU 486.

The regulation of aromatase activity (AA) in human endometrial stromal cells by various steroids was studied in primary cell culture. Various progestins, but not androgens or glucocorticoids, stimulated AA. Medroxyprogesterone acetate (MPA) was the most potent progestin. Estrogen (E) alone did not change the activity but it potentiated the stimulation of AA by progestin. Biphasic regulation of AA by progestin was noted in both time- and dose-dependent manners. Endometrial AA was stimulated by MPA and reached the maximum rate between 2-5 days of incubation with subsequent decline of AA in prolonged culture. When stromal cells were treated with MPA (0.03 to 30 microM) for 3 days, AA was increased over the control at all the concentrations tested. The maximum was found at doses between 0.1-1 microM. The activities reduced steadily from the maximum stimulation to less than 50% when the concentration of MPA increased from 1-30 microM. In addition, initial treatment of stroma cells with MPA (1-3 days) resulted in further increase of activity after progestin withdrawal. The enhancement of the induction of AA by E did not alter the biphasic pattern regulated by progestin alone, i.e. E enhanced both the stimulation and the decay of AA. The time study of the effect of E showed that enhancement of AA required at least 10 h of incubation of E with MPA conditioned cells. The effect of E is dose dependent between 0.04-40 nM and shows the greatest effect in the presence of MPA between 0.01-1 microM. The optimal concentrations of E and progestin that stimulate AA in culture are similar to the plasma concentrations after pregnancy, suggesting that the physiological function of the endometrial aromatase is at the time of decidualization. The effects of antiprogestin, Ru 486, and antiestrogen, tamoxifen (TAM), on AA were studied. Ru 486 or TAM alone did not alter AA. Ru 486 inhibited the MPA stimulated AA in a dose-dependent manner suggesting that the effect of progestin may be mediated through a receptor mechanism. Enhancement, but no inhibitory effect, was observed when cells were treated with TAM + MPA and TAM + MPA + E. The effectiveness of Ru 486 to inhibit the induction of AA in endometrial cells may be of primary importance for contraception.

Adult↗
PubMedDate not supplied

Discrete intracellular Ca(2+) pools coupled to two distinct Ca(2+) influx pathways in human platelets.

Ca(2+) influx is an important event associated with platelet activation and regulated by the content of intracellular Ca(2+). Previous studies have suggested two different Ca(2+) pools and two Ca(2+) influx pathways exist in platelets. In the present study, we have investigated the regulation of thrombin- and thapsigargin-induced Ca(2+) entry into human platelets, using fluorescent indicators to monitor Ca(2+) mobilization and membrane potential. It was found that depletion of thapsigargin-sensitive Ca(2+) stores was coupled to Ca(2+) influx through a Ca(2+)-selective pathway. Additional release of Ca(2+) from the thapsigargin-insensitive pool by thrombin caused the opening of a nonselective cation channel.

Blood Platelets↗
PubMedDate not supplied

Effect of amiloride and surfactant on lung liquid clearance in newborn rabbits.

Immature and nearly mature fetal rabbits (gestational age 27.5 and 29.5 days, respectively) were obtained by hysterotomy and tracheotomized at birth. Immature rabbits received, via the tracheal cannula, 2.5 ml/kg of either normal saline, porcine surfactant (60 mg/ml), 1 mM amiloride in normal saline, or a mixture of surfactant and amiloride; nearly mature rabbits received either normal saline, or 1 mM amiloride in saline. The neonates were ventilated with a tidal volume of approximately 10 ml/kg for 0-60 min (immature animals) or 0-120 min (nearly mature animals). The lungs were then excised for determination of wet lung weight/body weight ratio (LW/BW). The right lung was further processed for quantification of extravascular lung water (EVLW) per unit dry lung weight, and the left lung fixed for measuring the size of perivascular 'cuffs' (adventitial tissue including lymphatics) in histological sections, using vascular lumen as reference volume. Immature animals receiving surfactant had improved compliance and smaller perivascular cuffs in comparison with the other groups. In immature animals amiloride had no effect on compliance, LW/BW, and EVLW, but reduced perivascular cuff size at 15 min. Nearly mature animals receiving amiloride had higher values for LW/BW and EVLW at 120 min, and lower perivascular cuff size at 15, 60, and 120 min, in comparison with saline-treated litter-mates. We conclude that surfactant improves lung-thorax compliance and reduces perivascular fluid accumulation in immature newborn animals without influencing total lung water content, and that amiloride retards fetal lung liquid resorption in nearly mature newborn animals without affecting lung-thorax compliance during artificial ventilation.

Absorption↗