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Biomedical subjects

S Y Yu

Publications and source records attributed to S Y Yu.

At least 91 records · Page 5Linked to original sources
PubMed1982

Factors regulating lamellar body volume density of type II pneumocytes in excised dog lungs.

Pulmonary arterial occlusion (PAO) produces multiple alterations in the physiological/biochemical environment of lung cells as well as dysfunction of the lung's surfactant system, which is considered to play a significant role in mediating lung injury. The present studies were performed using 66 excised dog lungs to evaluate the impact of alterations in ventilation, substrate availability, alveolar CO2 tension, hydrogen ion and bicarbonate concentrations, and temperature and neural denervation on the lamellar body (LB) volume density of type II pneumocytes. Ventilating excised nonperfused dog lungs with room air (0% CO2) for 4 h at 38 degrees C resulted in severe reductions (68-77%) in LB volume density. Supplementing inspired gas with 5% CO2 prevented LB depletion, while ventilation with 2.5% CO2 moderated the severity of depletion to 17-27% of control. Ventilation with 10% CO2 tended to increase LB volume density by increasing the number of LBs per cell, whereas reductions in LB volume density predominantly resulted from a decrease in LB size. The level of ventilation had no significant effect on LB volume density independent of inspired CO2 concentration. Reducing temperature to 5 degrees C prevented LB depletion. Lung perfusion with autologous whole blood failed to moderate the severity of LB depletion during room air ventilation despite the increased availability of metabolic substrates for cellular metabolism. Adding hydrochloric acid to maintain physiologically normal hydrogen ion concentrations in the perfusing blood had a small effect in ameliorating the severity of LB depletion. These results indicate that alveolar CO2 tension and bicarbonate concentration are major factors regulating the LB content of type II pneumocytes and suggest an important link between the gas exchange and phospholipid metabolic functions of the lung.

Animals↗
PubMed1981

Urinary excretion of desmosine in patients with severe burns.

Urinary excretion of total desmosine was measured by a radioimmunoassay in severely burned adult males, as well as in normal adult males. Total urinary desmosine was significantly elevated in all the samples in the burned patients, who had injuries involving more than 19% of total body surface area. The values of 24-hr urinary desmosine for the burned patients ranged from 250--1,411 nmoles, as compared with 82--142 nmoles for normal controls. These were equivalent to 14--78 mg of elastin degraded for the burned patients and 5--8 mg for normal controls. Urinary desmosine values expressed as nmoles per g of creatinine were also higher than the corresponding normal values, ranging from 110--768 nmoles versus 63 +/- 6 nmoles for normal controls. Urinary excretion of total hydroxyproline in the burned patients was also higher than in normal controls, ranging from 56--471 mg per 24 hrs, or 36 to 413 mg per g of creatinine, vs. 31 +/- 6 mg per 24 hr, or 23 +/- 2 mg per g of creatinine, in burned patients and normal controls, respectively. These values of hydroxyproline were equivalent to 413--3,623 mg of collagen and 238 mg of collagen, respectively. In the burned patients, both urinary desmosine and hydroxyproline values were elevated from day 1 post-burn, and reached peak levels in days 2--12, declining thereafter but remaining higher than values for normal controls through day 60. The metabolism of elastin and collagen in skin of burned patients was probably highly accelerated for a long time, at least through day 60 post-burn.

Adult↗
PubMed1980

Desmosine radioimmunoassay for measuring elastin degradation in vivo.

Desmosine is a cross-link amino acid unique to elastin. Previous work has shown that during turnover in the body, desmosine is not reused, and that desmosine is not absorbed from the intestine. Instead, all desmosine released in the course of elastin metabolism is excreted in the urine attached to low molecular weight peptides. Therefore, measurement of desmosine in acid-hydrolysates of urine might be used to monitor elastin breakdown in several pathologic states, including pulmonary emphysema. In the present report, we have described a sensitive, highly specific radioimmunoassay capable of detecting as little as 200 pg of desmosine in acid-hydrolysates of urine. The assay was specific for desmosine; cross-reactivity with merodesmosine, isodesmosine, lysine, and mixed amino acids was 0.25%, 0.1%, less than 0.0003%, and 0%, respectively. Twenty-three normal, nonsmoking subjects had a mean 24-hr desmosine excretion of 47 +/- 15 microgram. In a group of smokers with evidence of chronic obstructive disease and/or lung infection, the values for desmosine excretion ranged from 40 to 400 microgram/24 h. Desmosine radioimmunoassay may find application in the study of diseases involving increased destruction of elastin in the body.

Adolescent↗
PubMed1979

Association of prealbumin deficiency with alpha-1-antitrypsin deficiency.

Prealbumin (PA) measurements were made by electrophoretic and radial immunodiffusion techniques in three alpha-1-antitrypsin deficient Pi-D) serum samples. The deficiency was characterized as phenotype ZZ (homozygous). In two out of three serums PA was undetectable, as revealed by the absence of radiothyroxine distribution in the PA area, whereas quantitative estimates of PA by radial immunodiffusion showed very low levels (2--7 mg/100 ml) thus corroborating electrophoretic observations; low PA binding of T4 tracer was noted in another Pi-D serum. The total protein and laboratory thyroid function (thyroxine, triiodothyronine, and free thyroxine index concentration) measurements were normal, and the decrease in PA could not be explained on the basis of surgery, protein malnutrition, or cirrhosis. These and other observations described in this preliminary communication have served to raise the possibility of severe prealbumin deficiency being associated with alpha-1-antitrypsin deficiency, while the presence of low-but-not-absent PA in another Pi-D case might also suggest subgroup classification of the phenotype ZZ based on degrees of PA deficiency.

Adult↗
PubMed1977

The fate of 14C-elastin in the peritoneal cavity of rats. I. Biochemical studies.

Degradation of elastin was studied in rats after intraperitoneal implantation of a suspension of 14C-elastin that had been prepared by labeling bovine elastin with 14C-formaldehyde. Most of the degradation of 14C-elastin, measured by releasing the radioactivity in urine and feces, occurred between 6 and 15 days after the implantation. During this period an increase of leukocytes and macrophages in the implanted site was observed. This followed a brief increase in neutrophils. Furthermore, an elevation of the elastolytic activity, measured by the 14C-elastin, was found in cell lysates of both macrophages and neutrophils, which were recovered by lavage of the peritoneal cavity. But the enzymatic activity was not found in the cell-free lavage. On the contrary, there was elastase inhibitor in the lavage, increased by the implantation. The mechanism of the elastin degradation in the peritoneal cavity was discussed.

Animals↗
PubMed1976

The induction of emphysema with elastase. II. Changes in connective tissue.

Both clinical and experimental evidence implicate proteolytic enzymes active against elastin in the pathogenesis of emphysema. Paradoxically, however, the elastin content of emphysematous human lungs at autopsy has been normal. When emphysema was produced in hamsters by a single intratracheal injection of 25 units of porcine pancreatic elastase, the elastin content of the lungs was reduced from 1.40 +/- 0.22 mg. in controls to 0.43 +/- 0.10 mg. 24 hours after injection, and histologic sections showed that many elastic fibers had disappeared. The elastin content of the lungs gradually increased, approaching normal values by 2 months after injection. The incorporation of 14C-proline into elastin was markedly elevated during the first 2 weeks after injection, decreasing nearly to normal by 2 months. The synthesis of collagen was also increased, indicated by an increase in the collagen content of the lung, an increase in the prolyl hydroxylase activity, and an increase in incorporation of labeled proline into collagen. During the period of active resynthesis of elastin, small clumps of microfibrils and elastic fibrils were visible by electron microscopy within grooves on the surface of septal connective tissue cells in the lungs. Many elastic fibers seen in histologic sections up to 4 months after injection were of abnormal configuration and disorganized.

Animals↗