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Biomedical subjects

R W Chen

Publications and source records attributed to R W Chen.

34 records · Page 2Linked to original sources
PubMed1994

[Experimental study of myocardium protection with warm blood cardioplegia].

The present paper has shown the effects of myocardial protection of isolated rat heart which were infused with different kinds of cardioplegia, and made to be arrested in the state of ischemia and absence of oxygen for 120 min. The heart rate, left ventricular constraction pressure and cardiac output volume, the myocardium water content and calcium content and pathological examination of myocardium were observed. The isolated rabbit heart under the circumstances of ischemia and absence of oxygen at 37 degrees C for 20 min Observations of the different kinds of cardioplegia. was observed that the different pH and oxygen content between artery and vein of the heart during the infusion of cardioplegia, the value of left ventricular constraction pressure multiplied by heart rates after reperfusion with autologous artery blood for 20 min. The values of CPK and MDA in right atrial blood, the ATP and CP volume of myocardium and pathologic study of myocardium were carried out. The results demonstrated that the warm blood cardioplegia had a better myocardial protection effect in supplying sufficient oxygen to myocardium during heart arrest, preserving and increasing energy store; controlling reperfusion in jury after ischemia, buffering acidosis and preserving heart status function. Therefore it has great value for improving the safety of the patients with complex and high risk heart diseases in perioperation.

Adenosine Triphosphate↗
PubMed1994

[Myocardium protection using warm blood cardioplegia in corrective operation of tetralogy Fallot].

In this paper, the children, who had undergone the operation with the approach similar to that of Tetralogy Fallot, were selected and divided into 4 groups, according to different kinds of cardioplegia were infused during corrective operation. St. Thomas group (CC group) 24 cases, cold blood cardioplegia group (CBC group) 21 cases, terminal warm blood cardioplegia group (TWBC group) 12 cases, and continuous warm blood cardioplegia group (CWBC group) 12 cases. Through the measurement of left ventricular contraction pressure and CK-Mb release in the postoperative period, the effect of myocardial preservation was better in TWBC and CWBC groups than in CC and CBC groups (P < 0.05), ATP volume of myocardium in TWBC and CWBC groups were higher (17.1 and 18.2 mumol/g) than that in CBC group (2.48 mumol/g) (P < 0.01) CP values were respectively 8.74 mumol/g, 7.63 mumol/g and 5.5 mumol/g (P < 0.05). 9 cases (37%) in CC group needed inotropic drug to assist circulation postoperation, 4 cases (16%) in CBC group, 2 cases (12%) in both TWBC and CWBC group. The results demonstrated that WBC had a better myocardial protection effect.

Bicarbonates↗
PubMed1977

Accumulation and depletion of zinc in rat liver and kidney metallothionens.

The accumulations of zinc in liver and kidneys of rats fed various dietary levels of this element was investigated. Zinc started to accumulate in rat liver when 1,000 ppm or higher levels of this element were fed in the diet, but not when the dietary zinc level was 500 ppm less. Almost all of the accumulated zinc in the soluble fraction was found to be present in the metallothionein (MT) fractions. When rats were fed a diet supplemented with 2,000 ppm, zinc, the metal rapidly accumulated in MT in the liver and kidneys. The accumulated zinc was, however, depleted to the pre-supplementation level after only 3 days of feeding a zinc deficient diet. While rats were fed the zinc deficient diet, in which the element was simultaneously depleted from MT, significant increased excretion of the metal occurred in the feces urine. No evidence was found to indicate that zinc was excreted in the bile in association with MT. It was therefore concluded that MT is probably, as one of its possible biological roles, more involved in accumulation of excessive zinc rather than in storage of the metal for later utilization.

Animals↗
PubMed1976

Influence of dietary selenite on the binding characteristics of rat serum proteins to mercurial compounds.

The effect of dietary selenite on the binding characteristics of serum proteins was investigated with rats. In the control serum, the maximal binding of phenylmercuric acetate (PMA) and methylmercuric chloride (MMC) to rat serum protein was approx. 18 and 9 nmoles per mg protein, respectively. The binding of Hg2+ was biphasic and it did not reach a maximum at the concentrations used. Selenite treatment caused a reduction in binding capacity of serum proteins to Hg2+ and PMA, and an increase in the binding affinities. However, there were no such changes for the binding of MMC. Selenite protection from mercury toxicity, therefore, acts not only via a change in tissue distribution and a change in the formation of seleno-proteins but, also, via a change in the binding characteristics to some mercury compounds. In the case of methylmercury, a different mechanism of protection must exist as the modification of tissue distribution, its binding to subcellular and soluble proteins and the binding characteristics remained equivocal.

Administration, Oral↗
PubMed1975

Selenium - induced redistribution of cadmium binding to tissue proteins: a possible mechanism of protection against cadmium toxicity.

The mechanisms involved in the protection by Se against Cd toxicity in the rat were investigated. Se was found to significantly increase the Cd content in the blood and the testis, while decreasing that in the liver and kidney. Se diverted almost all the Cd in the soluble fraction of the testis from low-molecular-weight (MW) proteins to larger ones. Since the soluble fraction was the major subcellular Cd-binding component, the diversion of Cd by Se appears to be a mechanism involved in the protection by this element against the Cd-induced testicular injury. The diversion in binding of the Cd in the soluble fraction to higher MW proteins was also observed in the kidney and liver, and may be a second mechanism involved in the protection of these organs against Cd by Se, in addition to the reductive effect of Se on the tissue Cd concentration. Se was also found in these higher MW Cd-binding proteins. Based on a similarity of MW of about 115,000, the Cd-binding, Se-containing proteins found in these organs appear to be similar. A diversion of Cd from lower MW proteins to larger ones by Se was also found in the plasma, but the Cd-binding, Se-containing proteins in plasma appear to be different from those found in the other organs since they have a larger MW.

Animals↗
PubMed1975

Some properties of a unique cadmium-binding moiety in the soluble fraction of rat testes.

A 30,000 molecular weight testicular Cd-binding peak (30,000 MW Cd-BP) previously implicated in Cd-induced testicular injury was unstable during storage with respect to apparent molecular weight determined by Sephadex G-75 chromatography. Storage of testicular cytosol labeled with 109Cd in vivo or in vitro for several days at 4 degrees C under nitrogen resulted in disappearance of the 30,000 MW Cd-BP and increased 109Cd uptake in other protein fractions. Rechromatography of the previously isolated 30,000 MW Cd-BP after storage gave rise to a 109Cd peak eluting in the higher molecular weight region. The latter effect was prevented by 1 mM dithiothreitol, suggesting that sulfhydryl groups were involved in the apparent aggregation. The 30,000 MW Cd-BP found in testes of rats was not present in testes of roosters, nor in liver and kidney of either species, providing further evidence of a correlation between the occurrence of 30,000 MW Cd-BP protein in the tissue and susceptibility to Cd-injury. The inability of parenterally administered HgCl2 to induce testicular injury compared to the same dose of CdCl2(0.011 mmol/kg) is apparently related to the poor uptake of Hg in the testes (one-eighteenth that of Cd) rather than to an inability of Hg to bind to the 30,000 MW Cd-BP. Our studies indicate that binding of Cd to this unique 30,000 MW testicular component, as yet unidentified, is a possible basis for the unique sensitivity of the testis to Cd injury.

Animals↗
PubMed1975

Effect of selenium on methylmercury binding to subcellular and soluble proteins in rat tissues.

The possible mechanism involved in the protection of Se against the toxicity of methylmercury was investigated with rats. Pretreatment with Se increased the Hg content slightly in the blood (30%), moderately in the testes (doubled), and markedly in the brain (5 times), while decreasing that in the kidneys by half. The Hg content in the liver, spleen, heart and plasma was not significantly affected. Of the subcellular fractions, most (40-50%) of the tissue Hg was found in the soluble fraction (cytosol) of the liver, kidneys and spleen, but not the brain which had 65% of its Hg located in the crude nuclear fraction and only 24% in the soluble fraction. Se did not significantly affect the subcellular Hg distribution other than that which could be accounted for by its effect on the whole tissue uptake. In the soluble fraction, most of the Hg was associated with hemoglobin-containing and low molecular weight (MW less than 5,000) fractions, which is in contrast to reported data for inorganic Hg which binds to metallothionein (MW = 10,000). The distribution pattern of methylmercury between different molecular weight proteins within the soluble fraction was not significantly affected by Se which is also in contrast to reported work on inorganic Hg. Thus, Se pretreatment may protect the kidneys by reducing their methylmercury uptake, but apparently protects other organs by a different mechanism. The possible mechanism of protection by Se against inorganic Hg in which this element is diverted to presumably less critical proteins in the soluble fraction is apparently not operating in the case of methylmercury.

Animals↗
PubMed1975

Relative cadmium-binding capacity of metallothionein and other cytosolic fractions in various tissues of the rat.

The Cd-binding capacity of soluble proteins in 10 tissues of normal rats not excessively exposed to heavy metals was measured by saturation of freshly isolated cytosol with 109CdCl2 in vitro followed by Sephadex G-75 chromatography. The Cd-binding capacity of a 10,000 molecular weight Cd-binding peak (10,000 MW Cd-BP), which had a high affinity for Cd and was probably metallothionein, was the highest in kidney (78nmol Cd/g fresh tissue), followed by testis (63 nmol/g), liver (38 nmol/g) and then by brain (14 nmol/g). The amount of the Cd-BP in these tissues (assuming that it was metallothionein and bound 9 mol Cd/10,000g) was calculated to be 87, 70, 42 and 16 mg/kg fresh tissue in kidney, testis, liver and brain, respectively, or in the order of 10(-5) to 10(-6) mol/kg tissue. A significant amount of the 10,000 MW Cd-BP was also found in small intestine. It was present in rather small amounts in heart and lung, and possibly in spleen and skeletal muscle as well. In contrast, the protein was not detectable by this technique in plasma. The results suggest that metallothionein is a rather ubiquitous, intracellular protein in tissues of normal animals and may have other biological functions, besides its possible fortuitous role in heavy metal detoxification. A 30,000 molecular weight Cd-binding peak (30,000 MW Cd-BP) having a very high affinity Cd, apparently higher than that of the 10,000 MW Cd-BP, was found only in testes, among the 10 tissues examined. Its estimated Cd-binding capacity was 51 nmol Cd/g of testis, slightly less than that of metallothionein in testis. These findings support the hypothesis that the 30,000 MW Cd-BP is a plausible target of Cd in Cd-induced testicular injury, and suggest a basis for the peculiar sensitivity of the rat testis to Cd.

Animals↗
PubMedDate not supplied

The development of the RISK tool for fall prevention.

The authors tailored a 26-item risk assessment tool (RAT) for falls based on a literature review and an analysis of causative factors of falls that had occurred over a 3-month period at the Olin E. Teague VA Medical Center, an 1,100-bed acute medical-surgical, psychiatric, and extended care facility in Temple, TX. The RAT was completed by nursing staff on 10 patient units (four medical, four surgical, and two nursing home units) for all admissions during the period. A 25% sample of the completed RATs was randomly selected (n = 208). Pearson's correlation coefficient was used to identify factors that would most likely predict falls from the RATs of the randomly selected group and of the patients who fell (n = 78). Only 4 of the 26 items were statistically related to falls. Based on findings from this study, the RAT was shortened to the four items and called the RISK (Reassessment Is Safe "Kare") tool.

Accidental Falls↗