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C Chen

Publications and source records attributed to C Chen.

At least 1,153 records · Page 64Linked to original sources
PubMed1990

Scapholunate advanced collapse: a common wrist abnormality in calcium pyrophosphate dihydrate crystal deposition disease.

Scapholunate advanced collapse (SLAC) is a pattern of wrist malalignment that has been attributed to posttraumatic or spontaneous osteoarthritis of the wrist. Its features, however, also have been observed in patients with idiopathic calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. To determine the frequency and characteristics of SLAC in this disease, the authors reviewed wrist radiographs in 168 well-documented cases of this disorder. Forty-four of the cases (26%) revealed wrist abnormalities typical of SLAC. Associated findings included bilateral involvement (63%); calcification in or near the triangular fibrocartilage (70%); scapholunate widening or dissociation (70%); and arthropathies of the trapezioscaphoid (57%), metacarpophalangeal (second through fifth) (52%), first carpometacarpal (40%), and radiolunate (14%) joints. Results strongly suggest that CPPD crystal deposition disease is one of the major causes of SLAC. Furthermore, radiolunate arthropathy was found in 14% of the patients with SLAC and CPPD crystal deposition disease, which is different from other observations.

Aged↗
PubMed1990

Somatostatin increases voltage-dependent potassium currents in rat somatotrophs.

To study the modulatory effects of somatostatin on membrane K+ currents, whole cell voltage-clamp recordings were performed on identified rat somatotrophs in primary culture. In the presence of Co2+ (2 mM) and tetrodotoxin (1 microM) in the bath solution to block Ca2+ and Na+ inward currents, two types of voltage-activated K+ currents were identified on the basis of their kinetics and pharmacology. First, a delayed rectifier K+ current (IK) had a threshold of -20 mV, did not decay during voltage steps lasting 300 ms, and was markedly attenuated by extracellular application of tetraethylammonium (TEA, 10 mM). Second, a transient outward K+ current (IA) was activated at -40 mV (from a holding potential of -80 mV) and persisted despite the presence of TEA. This IA was blocked by 4-aminopyridine (2 mM). Somatostatin (10 nM) increased IK by 75% and IA by 45% without obvious effects on steady-state voltage dependency of activation or inactivation, and these effects were reversible. This increase in K+ currents may contribute in part to the inhibitory effect of somatostatin on growth hormone release.

4-Aminopyridine↗
PubMed1990

Insufficiency fracture of the sternum caused by osteopenia: plain film findings in seven patients.

Sternal insufficiency fractures, whether nonbuckling (displaced or nondisplaced) or buckling, are rare and have been described in elderly osteopenic patients with accentuated kyphosis of the thoracic spine. We retrospectively analyzed the radiographs and clinical records in seven osteopenic patients with sternal insufficiency fractures and correlated the type of insufficiency fracture with the presence and degree of dorsal kyphosis, as well as the presence of chest pain, soft-tissue mass, and osteolysis. We found that displaced or nondisplaced nonbuckling fractures (five patients) may be associated with chest pain localized to the sternum (three patients), and may be present with (three patients) or without (two patients) associated thoracic kyphosis. This type of insufficiency fracture also may be accompanied by a soft-tissue mass and osteolysis (three patients), findings simulating pathologic fractures. All buckling insufficiency fractures (two patients) were associated with thoracic kyphosis and were asymptomatic. Our findings suggest that sternal insufficiency fractures may occur with or without exaggerated dorsal kyphosis. The fractures are an uncommon complication of osteopenia and may resemble pathologic fractures when osteolysis and soft-tissue swelling are present.

Adult↗
PubMed1990

The evaluation of subarachnoid administration of fentanyl for surgery and postoperative analgesia in patients undergoing cesarean section.

The use of spinal opioids for postoperative analgesia has gained popularity in recent years. In this study, subarachnoid fentanyl 20 micrograms was evaluated to determine its efficacy for postoperative analgesia, its possible side effects and its effects on the newborn. Sixty ASA class I or II at-term parturients undergoing elective cesarean section were randomly divided into two groups. In one group fentanyl 20 micrograms (0.4 ml) with 0.5% heavy marcaine 2.0 ml was given intrathecally and in the other group only 0.5% heavy marcaine 2.0 ml with CSF 0.4 ml was given intrathecally. The average time for patients in the fentanyl group to demand the first dose of narcotic for pain was 6.8 +/- 3.2 h and in the control group it was 3.9 +/- 1.1 h. The incidences of postoperative nausea and vomiting were higher in the fentanyl group than in the control group. Pruritus was only found in the fentanyl group and amounted to 50%. Early or late respiratory depression was not found in the fentanyl group. During operation, all patients were wakeful and alert. Neonatal condition as determined by 1-min and 5-min Apgar score was satisfactory and showed no significant difference in both groups. Examination on neurobehavior and reflexes done at the baby room showed no abnormality in both groups.

Adult↗
PubMed1990

Cloning and identification of a rabbit sperm membrane protein gene.

Antibodies raised against rabbit sperm membrane protein (rSMP-B) interacted with a rat testis cytosolic protein with an estimated molecular weight of 70 kD. The clone expressing rSMP-B was isolated by epitope selection from a rat testis lambda gt11 vector cDNA library. An Eco R1-cut 2.0 kb cDNA fragment encoding rSMP-B was identified. The cDNA fragment (RSD-1) was isolated, subcloned and restriction mapped. Dot hybridization analysis of mRNA prepared from human, rabbit and rat testes showed that the gene encoding rSMP-B is expressed in the testes of all three mammals.

Animals↗
PubMed1990

Ilioinguinal nerve block with 0.375% marcaine for postoperative pain relief in cesarean section.

Bilateral ilioinguinal nerve block with local anesthetic drugs to treat postoperative pain in lower segment cesarean section (Pfannestiel incision) under general anesthesia had show profound effective by P. Bunting and I. McConachie. We used the same method but with lower concentration 0.375% marcaine 10 ml to each side in 12 patients. We compare the pain score and the requirement for pethidine intramuscular injection to 12 patients as control group. Pain score were less in the block patients within 8h after surgery, and total amount of pethidine given was 700 mg. In control group, the pain score were higher at the first 8 h than nerve block group during the study (p less than 0.05), and the total amount of pethidine requirement was 1250 mg. There were no observed adverse effect during the study.

Adult↗
PubMed1990

[Ilioinguinal nerve blockade with or without epinephrine for analgesia after caesarean section].

The analgesic effect of bilateral ilioinguinal nerve blockade with or without epinephrine after caesarean section with Pfannenstiel incision was investigated in 36 ASA class 1-2 parturients. They were randomly classified into 3 groups of 12 each. Before the patients were extubated from standard general anesthesia, bilateral ilioinguinal nerve blockade was performed. Group A patients were the control group. Group B patients received 0.375% plain marcaine 10 mL to each side. Group C patients received 0.375% plain marcaine with 1:200000 epinephrine 10 mL to each side. The pain scores and requirement for post operative analgesia of group B and C were compared with the control group A. The pain scores of group B and C were decreased 30% and 37% respectively during the first eight hours after operation. However, group C patients had lower pain scores during the first day after operation. There was an increased time from anesthesia to the first injection of pethidine in group B and C when compared with group A (4.57 +/- 2.94, 4.38 +/- 2.72 and 1.8 +/- 0.9 hr, respectively). However, no significant difference between group B and C. The total pethidine requirement were decreased in group B and C although the mean pethidine dose was not statistically significant. The results suggest that bilateral ilioinguinal nerve blockade improve the quality of postoperative analgesia. The adding epinephrine can prolong the duration of nerve blockade.

Adult↗
PubMed1990

Optimization of asymmetric polymerase chain reaction for rapid fluorescent DNA sequencing.

A high-throughput method for the preparation of single-stranded template DNA, which is suitable for sequence analysis using fluorescent labeling chemistry, is described here. In this procedure, the asymmetric polymerase chain reaction is employed to amplify recombinant plasmid or bacteriophage DNA directly from colonies or plaques. The use of amplification primers located at least 200 base pairs 5' to the site of sequencing primer annealing removes the need for extensive purification of the asymmetric polymerase chain reaction product. Instead, the single-stranded product DNA is purified by a simple isopropanol precipitation step and then directly sequenced using fluorescent dye-labeled oligonucleotides. This method significantly reduces the time and labor required for template preparation and improves fluorescent DNA sequencing strategies by providing a much more uniform yield of single-stranded DNA.

Animals↗
PubMed1990

Sequencing reactions in microtiter plates.

We describe a simple and inexpensive method of performing sequencing reactions for 24 single-strand M13 DNA clones in microtiter plates. To simplify elevated temperature incubations during sequencing reactions, two heating blocks were designed to accommodate microtiter plates and fit within common laboratory heating modules. With only slight modification of standard fluorescent and radioisotopic sequencing methods, the sequencing reactions for 24 clones can be done in as little as 40 minutes.

Bacteriophages↗
PubMed1989

Evaluation of issues relating to the carcinogen risk assessment of chromium.

Important issues in the carcinogenic risk assessment of chromium compounds are whether both trivalent and hexavalent chromium compounds are carcinogenic, the role of solubility in the carcinogenic response, and the carcinogenicity of ingested chromium. Hexavalent chromium compounds are carcinogenic to animals via several routes of exposure, while trivalent chromium compounds, although they demonstrate evidence of genotoxicity, have not been shown in animal studies to be carcinogenic. Workers in chromate production plants, where the risk of lung cancer is elevated, are exposed to both trivalent and hexavalent chromium compounds. A cancer unit risk estimate for Wistar rats exposed to a hexavalent chromium aerosol (sodium dichromate) is less than the risk estimate for workers in chromate production. If this difference is biologically real, a possible explanation may be that trivalent compounds also have a carcinogenic effect. For hexavalent chromium compounds, it is contended that only sparingly soluble hexavalent chromium compounds are carcinogenic. Recent evidence, however, indicates that highly soluble hexavalent chromium compounds are also carcinogenic. Animal ingestion studies have not found trivalent chromium compounds to be carcinogenic by ingestion; hexavalent compounds have not been studied. Research by EPA to address the issue of valence state and solubility with respect to carcinogenicity is currently being conducted.

Animals↗
PubMed1989

Glycolipid glycosyltransferases in human embryonal carcinoma cells during retinoic acid induced differentiation.

Retinoic acid induced differentiation of TERA-2-derived human embryonal carcinoma cells is accompanied by a dramatic reduction of extended globo-series glycolipids, including galactosyl globoside, sialylgalactosyl globoside, and globo-A antigen (each recognized by specific MoAbs). Associated with these glycolipid changes, the activities of two key enzymes, alpha 1----4 galactosyltransferase (for synthesis of globotriaosyl core structure) and beta 1----3 galactosyltransferase (for synthesis of galactosyl globoside), were found to be reduced 3- to 4-fold. The latter enzyme plays a key role in the synthesis of extended globo-series structures, and its characterization has not been reported previously. Therefore, its catalytic activity was studied in detail, including substrate specificity, detergent and phospholipid effects, pH and cation requirements, and apparent Km. During retinoic acid induced differentiation, a series of Lex glycolipid antigens (recognized by anti-SSEA-1 antibody) and their core structures (lacto-series type 2 chains) increase dramatically. In parallel with these changes in glycolipid expression, the activities of two key enzymes, beta 1----3 N-acetylglucosaminyltransferase (for extension of lacto-series type 2 chain) and alpha 1----3 fucosyltransferase (for synthesis of Lex structure), were found to increase by 4- and 2-fold, respectively. Similarly, an increase in the expression of several gangliosides (e.g., GD3 and GT3) during retinoic acid induced differentiation was mirrored by a 4-fold increase in the activity of alpha 2----3 sialyltransferase (for synthesis of ganglio core structure, GM3). The results suggest a coordinate regulation of key glycosyltransferases involved in core structure assembly and terminal chain modification.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗