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C Chen

Publications and source records attributed to C Chen.

At least 1,171 records · Page 65Linked to original sources
PubMed1989

Vaginal reconstruction with an axial subcutaneous pedicle flap from the inferior abdominal wall: a new method.

A new method of vaginal reconstruction is reported. In the procedure, the left inferior abdominal wall flap with the subcutaneous pedicle containing epigastric superficial blood vessels and/or the circumflex iliac superficial vessel and the external pudendal vessel and their branches is raised and passed through an immediate extraperitoneal tunnel to be the artificial vagina. The operation is straightforward, quick, and safe. Thirty consecutive patients suffering from congenital absence of vagina have been treated. All flaps in the group, which were less bulky, survived completely. The follow-up survey was carried out from 6 months to more than 4 years postoperatively. There was no occurrence of hernia after surgery. The reconstructed vaginas in all patients were clean, soft, elastic, and expansible. Married patients indicated satisfaction with their sexual life.

Abdominal Muscles↗
PubMed1989

Electrophysiological responses to somatostatin of rat hypophysial cells in somatotroph-enriched primary cultures.

1. Somatotroph cells were obtained from pituitaries of adult male rats by dissociation, separation and enrichment on a continuous gradient of bovine serum albumin at unit gravity. They were kept in culture for 7-15 days before electrophysiological experiments. 2. Immunofluorescent staining of the resulting gradient fractions (numbered F2 to F9) indicated that the majority of somatotrophs (75-85%) were located in the heavy fractions (F8 and F9). However, a small percentage (15-20%) of cells in these fractions were identified as lactotrophs. 3. Perifusion experiments indicated that on the one hand release of growth hormone from somatotroph-enriched fractions was stable at the level of 6 ng (2 min)-1 (10(6) cells)-1 and was markedly inhibited by somatostatin (1.9 ng (2 min)-1 (10(6) cells)-1) but not by dopamine. On the other hand, in the same cell preparations, basal prolactin release (1.6 ng (2 min)-1 (10(6) cells)-1) was significantly reduced by dopamine (0.08 ng (2 min)-1 (10(6) cells)-1) but remained unchanged by somatostatin treatment. 4. The inhibitory effect of somatostatin on growth hormone release was dose dependent. This effect was not abolished by tetraethylammonium (40 mM) or 4-aminopyridine (5 mM), but somatostatin decreased high-potassium-induced release. 5. In all the cells recorded (n = 187), 14% (n = 26) displayed a low resting potential (less than -30 mV) and poor membrane resistance (less than 50 M omega). The recording was unstable and resting potentials decreased regularly to 0 mV in less than 5 min. The other 86% of the cells displayed resting potentials varying from -45 to -65 mV and had a membrane resistance of more than 150 M omega. Only cells which displayed these membrane characteristics showed clear responses to somatostatin or dopamine, and were therefore chosen for experiments. 6. In all the cells selected for the experiments (n = 161), 78% (n = 126) showed either triggered or spontaneous action potentials. The action potentials remained insensitive to sodium-free bath solution, but were reversibly blocked by the calcium channel blockers cobalt (5 mM) or nickel (5 mM). 7. When the cells were at resting potential, somatostatin induced a hyperpolarizing response associated with a decrease of membrane resistance. During this response, spontaneous or triggered action potentials were inhibited. The hyperpolarizing response induced by somatostatin was dose-dependent.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1989

FH3, a v-myc avian retrovirus with limited transforming ability.

We have isolated a new acute avian transforming virus which contains the oncogene myc. This virus, designated FH3, was isolated after injection of a 10-day-old chick embryo with avian leukosis virus. While FH3 shares many properties with other v-myc-containing avian retroviruses, it also has several unique properties. The primary target for transformation in vitro is chicken macrophages; infection of chicken fibroblasts does not lead to complete morphological transformation. FH3 also exhibits a limited host range, in that Japanese quail macrophages and fibroblasts are infected but are not completely transformed. FH3 induces in vivo a limited tumor type if injected into 10-day-old chick embryos; only a cranial myelocytoma, which does not appear to be metastatic, can be detected. The v-myc gene of FH3 is expressed predominantly as a P145 Gag-Myc protein which is encoded by a ca. 8-kilobase genomic RNA. This FH3-encoded polyprotein is localized in the nucleus of all infected cells, whether or not they are transformed.

Animals↗
PubMed1989

Electrophysiological responses of rat pituitary cells in somatotroph-enriched primary culture to human growth-hormone releasing factor.

The in vitro effects of human growth hormone releasing factor (hGRF, 1-44) were studied in somatotroph-enriched cultures (75-85%) obtained from adult male rat pituitaries. Cells perifused with hGRF showed an up to 800% increase in growth hormone (GH) release over basal values in a dose-dependent manner. Calcium current blockers (5 mM of Co2+, Ni2+ or Cd2+) completely inhibited this stimulating effect but sodium-free (choline) medium did not. Using a single-intracellular-electrode recording technique, it was found that hGRF induced a dose-dependent depolarizing response concomitant with a decrease in membrane resistance in 38% of the cells recorded (98 of 258 cells). The reversal potential of this response was close to -40 mV. This depolarizing response was recorded in both excitable and unexcitable cells with no marked difference. Co2+ and Ni2+ (5 mM) completely and reversibly inhibited the membrane response to hGRF. Application of hGRF and somatostatin (SRIF), a hormone that inhibits GH release, to the same cell cultures showed the existence of two subpopulations: one was responsive to both hGRF and SRIF (53%, n = 62), another was only responsive to SRIF (47%, n = 62). Human GRF did not affect prolactin release and did not modify the electrical properties of cells responding to dopamine and therefore considered as lactotrophs. These results suggest that (1) hGRF leads to an increase in growth hormone release and a modification of membrane electrical properties by means of an extracellular Ca2+-dependent pathway, and (2) according to their responses to SRIF and hGRF, there are at least two subpopulations of somatotrophs.

Animals↗
PubMed1989

The calcium channel blocker diltiazem lowers serum parathyroid hormone levels in vivo and in vitro.

PTH secretion is inversely related to the extracellular and cytosolic calcium (Ca2+) concentrations and, therefore, might be affected by calcium channel blockers such as diltiazem. To investigate the effects of diltiazem on parathyroid function in vivo, 15 subjects were treated with diltiazem (120-360 mg/day), and 15 subjects were treated with the nonspecific vasodilator hydralazine (75-150 mg/day). Diltiazem lowered serum PTH levels from 1.07 +/- 0.07 to 0.87 +/- 0.07 pg/L (P = 0.001), and increased urinary calcium and decreased urinary phosphate excretion (P less than 0.001 and P less than 0.01, respectively). The hydralazine-treated subjects had no significant differences in any of these parameters. To investigate this effect further, dispersed bovine parathyroid cells were incubated for 2 h with or without diltiazem. Regression analysis of PTH released vs. the concentration of diltiazem (10(-7)-10(-4) mol/L) revealed a significant negative relationship (P less than 0.01) with 40% inhibition of PTH release at 10(-4) mol/L (P less than 0.01). The cytosolic Ca2+ concentration, measured using the Ca2+-sensitive fluorescent dye fura-2, was significantly increased in the presence of 10(-4) mol/L diltiazem (P less than 0.01). In summary, diltiazem lowered PTH levels in vivo and in vitro, perhaps acting as a Ca2+ channel agonist in the parathyroid cell and inhibiting PTH release through a rise in the cytosolic Ca2+ concentration.

Adult↗
PubMed1989

Overview of a workshop on quantitative models for developmental toxicity risk assessment.

A workshop was held to discuss potential advancements to improve the precision of risk estimates for developmental toxicity. This paper presents an overview of the discussions at the workshop, focusing on the risk assessment process and science policy considerations important in the use of quantitative models. Some of the pertinent biological considerations are reviewed, particularly those related to the repair capacity of the developing organism and how this affects the concept of a threshold for developmental toxicity effects, as well as the maternal and litter influences on developmental toxicity outcomes. Finally, the current status of use of quantitative approaches is described, possible short-term approaches are discussed, and future research needs in this area are outlined.

Abnormalities, Drug-Induced↗
PubMed1989

Alzheimer's disease: longitudinal CT studies of ventricular change.

A 3-year longitudinal study was conducted with 50 Alzheimer's disease patients and 45 elderly control subjects. All study participants received an extensive evaluation that included brain CT at baseline and follow-up. Quantitation of ventricular size, using both linear and volume methods, revealed highly significant cross-sectional and longitudinal differences between the Alzheimer patients and control subjects. Specifically, the annual rate of change in ventricular volume was approximately 9% in the Alzheimer patients and approximately 2% in the controls. The presence of age-related white matter lesions had no effect on the clinical course of the patients or on the changes in ventricular size. Among the Alzheimer patients, the rate of clinical decline was strongly related to the rate of change in ventricular size. Baseline ventricular measurements were of no value in predicting the subsequent rate of clinical deterioration or ventricular enlargement. The results suggest that changes in ventricular size closely reflect the clinical changes in Alzheimer patients.

Aged↗
PubMed1989

An analysis of intermediate fertility variables in Shanghai, Hebei and Shaanxi.

"On the basis of the data from China's first thorough survey on fertility [conducted in 1985], organized by the State Statistical Bureau, this study will analyze...intermediate fertility variables in Shanghai, Hebei and Shaanxi according to the [Bongaarts] Model. It will also provide a general survey of the model."

Asia↗
PubMed1989

Treatment of hyaline membrane disease by human amniotic fluid surfactant.

A case of hyaline membrane disease was treated successfully with pulmonary surfactant (PS) isolated from human amniotic fluid. Dosage was 150 mg phospholipid/kg. The exogenous surfactant was instilled into the airway via a tracheal cannula. Clinical symptoms, PO2 and FiO2 improved evidently 24 hours after administration. L/S ratio and phosphatidylglycerol recovered gradually in aspirates. Lung X-ray film manifested "white lung" before instillation of surfactant and showed a striking improvement 3 days after treatment. The duration of mechanical ventilation was 6 days. During the period of recovery complications of patent ductus arteriosus and bacterial pneumonia developed. However, the patient recovered completely and was discharged 32 days after admission.

Amniotic Fluid↗
PubMed1989

Coronary artery spasm complicating PTCA: role of intracoronary nitroglycerin.

During PTCA intracoronary (ic) nitroglycerin is used in our institution only in cases of suspected coronary artery spasm. In order to estimate the incidence of true spasm, records from 1400 consecutive PTCA procedures were retrospectively reviewed for use of ic nitroglycerin. For each of the 376 procedures where ic nitroglycerin was used, angiograms were reviewed to determine whether spasm had been present or whether there was some other complicating problem which had mimicked spasm. In 191 procedures (51%), spasm had apparently occurred. In 178 procedures (47%), there was evidence for dissection rather than spasm. Seven procedures (2%) had evidence for neither spasm nor dissection. These included three cases of guiding catheter injury, two procedures where unsuspected distal disease was found after opening of total occlusions, and one case each of branch vessel occlusion and no re-flow phenomenon. Spasm was more common during right coronary PTCA. It frequently occurred in areas remote from the PTCA site. In every instance spasm was reversed following administration of one or more boluses of ic nitroglycerin. On the basis of these data, coronary artery spasm occurs in 14% of PTCA procedures.

Angioplasty, Balloon↗
PubMed1989

[Studies on the analysis of some narcotic analgesics and CNS-stimulants].

Procedures for the separation and identification of 12 narcotic analgesics and 2 CNS-stimulants are described using GC/FID, GC/NPD and GC/MSD. The TFA and TMS derivatives were prepared by adding TFAA, MB TFA and MSTFA to the standard drugs. The mixture was heated at 70 degrees C for 30 min and chromatographed on FS capillary columns (SE-54, HP-5). Preliminary results show that all the derivatization with TFAA is better than that with MBTFA, but not much different from MSTFA derivatization. The method is reliable, fast and simple and may be used to screen these drugs and further applied to the analysis of biological fluids such as plasma and urine.

Analgesics, Opioid↗
PubMed1989

The role of the nucleus tractus solitarius and the locus coeruleus in the abdominal vagal pressor response.

The central mechanism of the pressor response induced by stimulation of the central ends of abdominal vagi (SCAV) was studied in 33 anesthetized cats. The results of the experiments showed that both electro-stimulation to part of the nucleus tractus solitarius (NTS) and SCAV caused similar rises of blood pressure. The microinjection of kainic acid into the NTS (40 mmol/L, 2 microliters) evoked a prolonged rise of blood pressure but did not affect the pressor response induced by SCAV. Electro-stimulation of the locus coeruleus (LC) also elicited a pressor effect. Kainic acid at blocking dose (40 mmol/L, 2 microliters bilaterally injected into the LC induced an increase followed by a decrease in blood pressure and markedly attenuated the SCAV's pressor response. Bilateral microinjections of phentolamine (4 micrograms/2 microliters), propranolol (2 micrograms/2 microliters) or 6-hydroxydopamine (6-OHDA, 8 micrograms/2 microliters) into LC had no significant effect on the pressor response, but atropine could markedly attenuate it. These results suggest that the pressor afferents in abdominal vagi do not terminate in but pass through the NTS and the neurons in the LC play an important role in the SCAV pressor reflex. Cholinergic transmission rather than catecholaminergic transmission in the LC may be involved in this pressor response.

Animals↗
PubMed1989

Hypercalciuric hypophosphatemic rickets, mineral balance, bone histomorphometry, and therapeutic implications of hypercalciuria.

A 14-year-old Turkish boy had severe rickets that had been clinically evident since he was 2 years of age. When he was 5 years of age, he had normal serum calcium and phosphorus levels and increased alkaline phosphatase activity. Treatment with modest dosages of vitamin D (5000 U/d for 3 weeks) resulted in hypercalcemia. At 10 years of age, high-dose vitamin D (40,000 U/d) plus phosphorus (1.1 g/d) therapy for 20 days resulted in symptomatic nephrolithiasis. When, 14 years of age, he had normocalcemia, hypophosphatemia, increased alkaline phosphatase activity, and normal circulating parathyroid hormone concentration. Levels of 25-hydroxyvitamin D were normal but those of 1,25-dihydroxyvitamin D were markedly increased. Rickets and osteopenia were evident on radiographs, and osteomalacia was present on trabecular bone obtained at biopsy. Balance study results showed increased intestinal absorption of calcium and phosphorus, hypercalciuria, and increased urinary phosphorus excretion. This patient manifests an unusual form of hypophosphatemic rickets in which hypercalciuria is a cardinal feature. In contrast with most varieties of hypophosphatemia, this disorder is characterized by appropriately increased production of 1,25-dihydroxyvitamin D in response to hypophosphatemia. It is recommended that urinary calcium excretion be assessed in all patients with hypophosphatemic rickets so that appropriate therapy will be instituted.

Adolescent↗
PubMed1988

Association and dissociation of the murine T cell receptor associated protein (TRAP). Early events in the biosynthesis of a multisubunit receptor.

The T cell antigen receptor on most mature T cells consists of at least seven chains (the variable, clone-specific alpha and beta chains, and five constant chains, CD3-gamma, -delta, -epsilon, and -zeta 2). These chains assemble rapidly after synthesis in the endoplasmic reticulum. In this paper we describe an additional protein termed TRAP (T cell receptor associated protein) that is transiently associated with at least some of the newly synthesized murine receptor chains. TRAP remains bound to receptor subunits as they assemble for about 10-20 min after synthesis. Rapid dissociation of TRAP ensues. This can be blocked by manipulations that inhibit endoplasmic reticulum to Golgi transport or with agents that inhibit organelle acidification. In mutant T cells that fail to synthesize the beta chains, the partial complex fails to reach the Golgi system. Despite this, TRAP dissociates with kinetics similar to those observed in the parental T cells. Thus, our studies indicate that the dissociation of TRAP occurs in a pre-Golgi compartment by a process that requires an acidic intraorganellar pH.

Animals↗