Biomedical subjects

C Pan

Publications and source records attributed to C Pan.

15 recordsLinked to original sources

PubMed1991

Soft filamentous woven polyester arterial prosthesis from China.

Woven polyester arterial prostheses have traditionally been known for their tight construction and smooth surface which has limited their healing capacity and resulted in poor attachment of their internal and external capsules. A new woven prototype has recently been developed in the Peoples' Republic of China. Among its unique features are its high physical porosity, softness and flexibility. This study undertook a series of in vitro tests to characterize its structure and physical properties in comparison with four commercial polyester grafts of North American origin. In addition, an animal trial was completed in which the new prototype was implanted as an infrarenal aortic substitute in 20 dogs for periods ranging from 4 h to 12 month. The in vitro tests confirmed a unique lightweight, highly porous, satin weave construction. Because of its high water permeability, preclotting was necessary before implantation. Once preclotted and installed, no significant blood loss was observed, and 19 of the 20 grafts remained patent at the sacrifice. Rapid full-width healing was achieved with tightly bound capsules, and more extensive tissue ingrowth was observed. Further work is needed to evaluate its long-term durability as an arterial substitute.

Animals↗

PubMed1991

Mesangial cell immune injury. Synthesis, origin, and role of eicosanoids.

The synthesis, cell origin, and physiologic role of eicosanoids were investigated in a model of mesangial cell immune injury induced by a monoclonal antibody against the rat thymocyte antigen Thy 1.1 also expressed in rat mesangial cells. A single intravenous injection of the antibody resulted in enhanced glomerular synthesis of thromboxane (Tx)B2, leukotriene (LT)B4, and 12-hydroxyeicosatetraenoic acid (HETE), whereas that of PGE2 and PGF2 alpha was either unaltered or impaired. The enhanced eicosanoid synthesis was associated with decrements in glomerular filtration rate (GFR) and renal blood flow (RBF). Complement activation mediated both the increments in TxB2, LTB4, and 12-HETE and the decrements in GFR and RBF. The decrements in GFR were abolished by the TxA2 receptor antagonist SQ-29,548. Although both neutrophiles and Ia (+) leukocytes infiltrated glomeruli, glomerular LTB4 originated mainly from the latter. Platelets entirely accounted for the enhanced 12-HETE synthesis in isolated glomeruli and to a lesser extent for that of LTB4 and TxB2. Glomerular PGE2 and PGF2 alpha originated from mesangial cells as their impaired synthesis coincided with extensive mesangial cell lysis. The observations indicate that in mesangial cell immune injury vasoactive and proinflammatory eicosanoids originate from recruited or activated Ia (+) leukocytes and platelets and may exert paracrine effects on mesangial cells.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1990

[An observation of protective effect of acupuncture on the gastric mucosa of Wistar rats and the relative histochemical changes of the neurotransmitters].

In this paper, changes of neurotransmitters and the protective effect of acupuncture on gastric mucosa have been studied by the histochemical methods of cholinesterase and catecholamine on 30 pairs of Wistar rats. 1. Sequential medical trials on rats of water-immersion induced gastric ulceration show that there was a protective effect of electro-acupuncture on gastric mucosa and it was statistically significant. 2. Under the protective effect of acupuncture on gastric mucosa, finally, both the cholinergic and adrenergic nerves undergo significant inhibition.

Acupuncture Therapy↗

PubMed1990

[The analysis of motivation and attitude of premarital medical examinees].

The study aims to analyse the motivation and attitude of premarital medical examinees. Ninety-two premarital medical examines, which include 46 self-paid persons and 46 government paid (subsidized by the Department of Health) visited the Family Clinic. They were studied from Oct. 27, 1988 to Nov. 8, 1989. Among 48 male and 44 female examinees, the sex ratio (male:female) was 1.09:1. The predominant age distribution was 26-30 y/o (58.2%); and the predominant level of education was college (54.4%). Questionnaires were sent to these premarital medical examinees. We received 70 questionnaires-47.1% from self-paid, and 52.9% from government paid. The recovery rate was 76.1%. The results of analysis were: 1) Concerning the motivation of examination, 35.1% of self-paid were introduced by relatives or friends; while 50% of government paid were introduced by newspapers; 41.2% of the total response were afraid of genetic disease. 2) Concerning the opinion of the examination fee, there were no significant differences between those of self-paid and government paid.

Adolescent↗

PubMed1990

The prevalence of subclinical hypothyroidism in adults with low-normal blood thyroxine levels.

The purpose of this study was to determine whether subclinical hypothyroidism, defined as the state in which there is an elevation of thyrotropin blood level (TSH) with a low-normal blood thyroxine level (T4), can be found in clinically healthy subjects. We identified, by screening of adults in an ambulatory patient care facility, 67 persons with T4 at the lower range of normal (4.5-6.0 micrograms/dL) who were free of acute nonthyroidal illness and who were not on medications known to affect T4, other than long term thyroxine therapy. TSH was determined in all 67 persons, whose ages ranged from 25 to 87 years. Nineteen persons in this population had a history of thyroid disease and 48 did not. Elevation of TSH was found in 13 subjects (19%), seven of whom had a history of thyroid disease. The prevalence of TSH elevation was 50% in those with T4 of 4.5- less than 5.0 micrograms/dL, 26% in those with T4 of 5.0-5.5 micrograms/dL, and 8% in those with T4 of greater than 5.5-6.0 micrograms/dL (p less than 0.02). Three of these 13 patients had been on thyroxine therapy at the time of the survey, and their thyroxine doses were adjusted, whereas five others were started on thyroxine therapy subsequent to the survey. Treatment doses as low as 0.05 mg/day increased the T4 and returned the TSH to normal in six patients. In two of five patients who went untreated, there was a substantial fall in T4 and/or a rise in TSH.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Normal free thyroxine in critical nonthyroidal illnesses measured by ultrafiltration of undiluted serum and equilibrium dialysis.

Considerable controversy exists concerning the assessment of thyroidal state in critically ill patients with decreased serum T4 and T3 concentrations, in part because serum free T4 values are often low in such patients no matter what method of measurement is used. We developed an ultrafiltration method to measure free T4 and free T3 in undiluted serum and compared the results with those obtained using a standard equilibrium dialysis method to measure free T4 and T3. In 30 consecutive intensive care unit (ICU) patients, serum free T4 values were similar to or higher than those in 12 normal subjects by both methods in most patients and were clearly distinguishable from those in hypothyroid patients. The serum total T4 concentrations in these patients ranged from 12.9-131.3 nmol/L (mean, 68.2; normal mean, 115.8). Free T4 by equilibrium dialysis was highly correlated with free T4 by ultrafiltration in the ICU group (r = 0.91; P less than 0.001). Serum free T3 levels, however, whether measured by equilibrium dialysis or ultrafiltration, were decreased in the ICU patients, confirming other reports of lowered free T3 in critically ill clinically euthyroid patients. Our findings suggest that the use of equilibrium dialysis of undiluted serum or ultrafiltration to measure serum free T4 concentrations will distinguish euthyroid hypothyroxinemic ICU patients from those with hypothyroidism.

Adult↗

PubMed1988

Amelioration of normothermic canine liver ischemia with prostacyclin.

A model of hepatic ischemia was developed in dogs using a pump-driven splanchnic-to-jugular vein bypass during crossclamping of the portal triad. An LD50 was established with three hours of ischemia. PGI2 given for one hour before the ischemic insult ameliorated the ischemic injury and increased survival.

Animals↗

PubMed1987

Prolongation of pig-to-dog renal xenograft survival by modification of the inflammatory mediator response.

The pathogenesis of hyperacute renal rejection consists of a nonspecific effector cascade that invokes most of the components of a typical acute inflammatory response. Platelet-activating factor (PAF) represents the most recent and perhaps the most significant mediator and promoting agent of this phenomenon. These studies evaluated SRI 63-441, a novel, synthetic, and the most potent PAF receptor antagonist available, alone and in combination with other prostanoids, for their ability to influence this response and to prolong renal xenograft survival and function in a model of pig-to-dog heterotransplantation. Inhibition of PAF by SRI 63-441 alone, at the dosage and schedule used in these experiments, did not significantly prolong xenograft survival or function. However, the combination of SRI 63-441 with either prostacyclin (PGI2) or prostaglandin E1 (PGE1) infusion demonstrated significant synergism, and resulted in a 6-9-fold increase in kidney survival and a 3-20-fold increase in urine output. Neither PGI2 nor PGE1 infusions alone significantly influenced this xenograft model. Electromagnetic flow studies demonstrated significantly delayed diminution in renal artery blood flow in the combination-treated animals. Serial and end-stage histologic examination of kidneys receiving combination therapy demonstrated a delayed onset of the pathologic deterioration and an overall amelioration of the entire process. These studies demonstrate that significant abrogation of a rapid and violent form of hyperacute rejection can be achieved solely by the pharmacologic manipulation of the inflammatory mediator response.

Alprostadil↗

PubMed1984

Thyroid hormone levels in diabetic mothers and their neonates.

Infants born to diabetic mothers have decreased activity of many metabolic pathways which might be regulated by thyroid hormone. Serum TSH, T4, T3, and reverse T3 levels were measured in 22 term infants of diabetic mothers and in 9 normal term babies at 2, 12, 24, and 72 hours of age, as well as in maternal and cord sera. T4 binding index and free T4 levels were measured in 11 diabetic mothers and their babies and 5 normal mothers and babies. Mean TSH levels did not differ between diabetic and normal mothers or their infants. Mean T4 of the diabetic mothers (9.6 micrograms/dl) was significantly (p less than 0.005) less than the mean T4 of the normal mothers (12.8 micrograms/dl). Mean T4 of neonatal specimens was lower in infants of diabetic mothers for each determination, but this difference achieved statistical significance at the 12-hour sample only (p less than 0.001). Mean serum T4 binding index was similar in the neonatal specimens at each time period studied. Mean T3 of diabetic mothers (149 ng/dl) was significantly (p less than 0.001) less than that of normal mothers (217 ng/dl). At each time interval, mean T3 concentration in infants of diabetic mothers was significantly lower than that of normal infants. Levels of reverse T3 were not significantly different between normal and diabetic mothers or their neonates. These data suggest that there is an effect of maternal diabetes on T3 secretion or conversion of T4 to the more active hormone, T3, in the fetus and early newborn.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1983