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Biomedical subjects

C C Chen

Publications and source records attributed to C C Chen.

At least 721 records · Page 40Linked to original sources
PubMed1977

The effect of diethylcarbamazine treatment on the development of bancroftian microfilariae in Culex p. fatigans.

Bancroftian microfilarie survived after one to three courses of diethylcarbamazine treatment in carriers and the larvae able to reach the infective stage in Culex p. fatigans. The infection rate and the development of infective larvae per infected mosquito from DEC-treated carriers was much lower than from the untreated carrier. The fact that surving MF can develop to infective stage in their vector indicates that such filarial carriers may be important sources for transmission of filariasis in the endemic areas after suspension of control measures.

Adolescent↗
PubMed1977

The diagnostic value of serum lysozyme activity in inflammatory bowel disease.

Serum lysozyme (muramidase) activity was determined by the Lyso-Plate diffusion technic in 419 subjects consisting of normal persons and patients with Crohn's disease, ulcerative colitis, nonspecific diarrhea and various other disorders. Lysozyme activity in the normal subjects did not exceed 37.8 microgram/ml. The values in the several groups of patients overlapped markedly with each other and with the normal range. Approximately two-thirds (62.1%) of the 37 patients with Crohn's disease had values that were within the normal range. In about half (51.8%) of the patients with this disease in whom the process was clinically active, serum lysozyme activity was increased. Of 10 patients with Crohn's disease who had undergone resection, heightened serum lysozyme activity was found only in the three patients in whom there was clinical evidence of recurrence of the disease. It is concluded that serum lysozyme activity is not a dependable means of distinguishing Crohn's disease from ulcerative colitis or nonspecific diarrheas. The determination would appear to be of value, however, in helping to identify activity, recurrence, or extension of the disease in patients with Crohn's disease.

Adolescent↗
PubMed1976

Blood coagulation studies during six day heparinless venoarterial bypass in sheep.

Heparinless venoarterial bypass (HL-VAB) was carried out in 16 sheep for 6 days, by means of a closed circuit tubing coated with nonthrombogenic polyurethane-polyvinyl-graphite (PPG) and a roller pump. Nine experiments were completed uneventfully. Seven sheep died during bypass. The causes of death were pneumonia (2), caseous granulomatous lung abscess (3) or abdominal abscess (1), and thromboembolism (1). The last complication was caused by inadverten trauma to the PPG coating at the time of tubing connection. In the animals in which HL-VAB was uneventful, no significant changes were noted in the hematologic studies including white blood counts, platelet counts, hematocrit, plasma fibrinogen levels, prothrombin time, thrombin time, activated partial thromboplastin time, Factors V and VIII, and free plasma hemoglobin levels. Inconsistant changes in the above parmeters were noted in the animals which died of complications. In conclusion, prolonged HL-VAB has no adverse effects on blood coagulation mechanism.

Animals↗
PubMed1976

Ventilation in conscious dogs during acute and chronic hypercapnia.

Minute ventilation was measured in conscious dogs, at rest and during exercise (1 mph), over 60 min immediately following the acute inhalation of 5% carbon dioxide in air and at 2, 4, 7, and 14 days while breathing the same gas mixture in a chamber. The dogs were also studied in the immediate period of air recovery from chronic hypercapnia and 1 day later. Control studies were carried out with the dogs breathing air in the chamber under comparable conditions. A triphasic ventilation change was ovserved in dogs at rest over the 14 days of hypercapnia. After an initial marked increase in ventilation during acute hypercapnia, ventilation returned to control levels by 2 days and then appeared to be elevated above control studies from 4 to 14 days at a time when blood acid-base balance became compensated. When the same dogs were studied during exercise, ventilation was also not different from air control at 2 days of hypercapnia; however during exercise, unlike the resting studies, there was only a tendency for a secondary increase in ventilation at 7 and 14 days of hypercapnia. During the immediate recovery from chronic hypercapnia when the dogs breathed air there was no evidence of hypoventilation either at rest or exercise despite arterial alkalosis. At 24 h of recovery it appeared that dogs while at rest had a slightly reduced ventilatory response to 5% carbon dioxide relative to control studies. The findings provide suggestive evidence that other factors, in addition to acid-base balance, might contribute to the regulation of ventilation during chronic hypercapnia and the recovery from chronic hypercapnia.

Acid-Base Equilibrium↗
PubMed1976

Successful prolonged heparinless venoarterial bypass in sheep.

In order to investigate the safety of prolonged heparinless venoarterial bypass (HL-VAB), we subjected 18 sheep to prolonged HL-VAB for up to 6 days. Three animals died of granulomatous lung abscess and one died from intra-abdominal abscess. One animal died of generalized thromboembolism secondary to mechanical damage of the nonthrombogenic coating occurring at the time of cannulation. HL-VAB was successfully carried out in 13 sheep. Although clots were found at all tubing connections where blood turbulence occurred, only the previously mentioned animal showed evidence of thromboembolism. Damage to the nonthrombogenic tubing exposed to the roller pump head was seen in all animals, and its severity appeared to be related to the duration of bypass. Scanning electron microscopic examination revealed scattered platelet aggregates on the nonthrombogenic coated surfaces without clinical evidence of embolization. Hematocrit values, leukocyte counts, platelet counts, prothrombin time (PT), activated partial thromboplastin time (PTT), thrombin time (TT), plasma fibrinogen levels, and factor V and VIII levels remained unchanged, whereas free plasma hemoglobin levels rose slightly during 6 days of HL-VAB. HL-VAB for up to 6 days appears to have little adverse effect on blood cells and blood coagulation factors. For current clinical use, the nonthrombogenic coated tubing circuit should be changed every 48 hours because of time-related trauma to the coated tubing from the roller pump.

Animals↗
PubMed1976

Mode of action of Vibrio cholerae enterotoxin in cultured adrenal tumor cells.

The effects of Vibrio cholerae enterotoxin on steroidogenesis and on formation of adenosine 3':5'-cyclic phosphate (cyclic AMP) in two adrenal tumor cell lines were compared. Steroidogenesis was half-maximal at concentrations of 1 ng of cholera toxin/ml in the mutant OS-3 cells and 3 ng of cholera toxin/ml in the parent Y-1 cells. At the end of an 8-hr incubation, toxin-induced formation of cyclic AMP in the mutant cell line was reduced by 90%. A molar ratio of GM1 ganglioside (galactosyl-N-acetylgalactosaminyl [sialosyl] lactosyl ceramide; GGnSLC) to cholera toxin of 3:1 caused half-maximal inhibition of steroidogenesis in both cell lines. When equine antiserum to choleragenoid was added to adrenal cells 15 min after cholera toxin, there was marked inhibition of cyclic AMP formation and of steroidogenesis. Pretreatment of Y-1 cells with adrenocorticotropin rendered them unresponsive to hormonal induction of cyclic AMP formation, but these cells had an unimpaired response to cholera toxin. These studies, utilizing two adrenal cell lines, suggest important differences between the mode of action of cholera toxin and that of adrenocorticotropin in cultured adrenal tumor cells.

Adenosine↗
PubMed1975

Negative arterial-mixed expired PC02 gradient during acute and chronic hypercapnia.

In resting conscious dogs physiological dead space was calculated using the Bohr equation and measurements of arterial and mixed expired carbon dioxide tension. Whenever dogs inhaled carbon dioxide mixtures (5-10%) that had normal or low oxygen concentrations, the calculated dead space became negative. This paradox was based on the fact that the mixed expired carbon dioxide tension in resting hypercapnic dogs. Under these circumstances carbon dioxide was produced from the lung as measured by gas analyses and blood analyses. By the lung as measured by gas analyses and blood analyses. By reasoning this implies that "alveolar" carbon dioxide tension was higher than pulmonary venous carbon dioxide tension. The negative carbon dioxide gradient persisted at 14 days of chronic hypercapnia and reverted to normal within 10 min of breathing air after chronic hypercapnia. These findings suggest that the exchange of carbon dioxide in the lung cannot be explained solely on the basis of passive diffusion.

Animals↗