Acute myocardial infarction in elderly Chinese. A clinical analysis of 631 cases and comparison with 389 younger cases

The purpose of this study was to define the clinical features of acute myocardial infarction in a group of elderly Chinese. The presenting symptoms, complications and mortality of acute myocardial infarction were compared in 631 patients (430 men and 201 women) aged 60 and over and 389 patients (333 men and 56 women) whose ages were under 60 years. The incidence of painless myocardial infarction was 17.6% in the elderly versus 5.9% in the younger group. Typical chest pain was present in 63.1% of the elderly and 84.3% of the younger Chinese. However, the incidence of other nonspecific presenting symptoms was higher in the elderly group. Likewise, the major complications in the elderly group were more severe than those in the younger group. For example, the incidences of cardiogenic shock, heart failure, arrhythmia, pulmonary infection and cardiac rupture in the older group were 19.8, 24.2, 77.2, 22.0 and 4.4%, versus 15.1, 19.5, 48.1, 9.5 and 1.1% in the younger group, respectively. The immediate (4 week) mortality rate of the older group was 21.9% (over 80 years 51.5%), but was only 11.0% in the younger group. Although the incidences of hypertension and pulmonary disease were significantly greater in the elderly group, these diseases alone did not account for the higher mortality rate in the elderly.

Selenium chemoprevention of liver cancer in animals and possible human applications

An inverse correlation between geographic distribution of liver cancer incidence and the selenium (Se) contents of whole blood and grains was observed in Qidong county, Jiangsu province, a high liver cancer area of the People's Republic of China. Animal experiments demonstrated that supplementation of Se reduced the incidence of liver cancer in rats exposed to aflatoxin B1. Se was also shown to inhibit the growth of transplanted tumors. A lower incidence of liver preneoplastic alterations and reduction of hepatitis B virus infection in ducks by Se-supplementation was observed, and three pilot studies for a Se-intervention trial on human liver cancer were carried out on the residents of Qidong county. A protective effect on the cellular DNA damage induced by aflatoxin B1 was observed in lympocytes from human with Se-supplements.

Biochemical and cellular aspects of the anticancer activity of selenium

Aberrant differentiation is a frequent hallmark of tumors, suggesting that modulators for differentiation and proliferation play a role in multistage carcinogenesis and that their use can also be exploited in cancer chemoprevention and therapy. We have demonstrated that selenium (Se) may be a modulator for the differentiation and proliferation of tumor cells. Evidence has been obtained that Se exerts the following effects: reversing changes of biochemical phenotypes toward normal levels, including reduction of cGMP level and cAMP-dependent protein kinase isozyme type I; increase in cAMP level and cAMP-dependent protein kinase isozyme type II, and altering membrane properties. Furthermore, we have obtained support for this hypothesis utilizing experiments on cultured human liver cell lines. It is demonstrated that Se can lead to the following changes: a. reduction of mitotic index; b. increase in the adhesiveness of cells; c. decrease in confluent saturation density and induction of an early contact inhibition; and d. decrease in tumorigenicity. For the purpose of comparison, the effects of Se on the normal counterparts was also studied. Contrary to what was observed above, there was no significant change in both biochemical and cellular aspects of normal cells treated analogously.

Decreased elastic fibers and desmosine content in incompetent cervix

Incompetence of the uterine cervix is a syndrome of painless, progressive dilatation and effacement occurring between the sixteenth and twenty-fourth weeks of gestation that represents abnormal functioning. It may serve as a model to elucidate normal function. Because the incompetent cervix results in painless opening of this organ without uterine contraction before term gestation, it is considered one of the causes of midtrimester spontaneous abortion, habitual spontaneous abortion, and early preterm labor. Untreated, it leads to rapid expulsion and often death of the fetus. We used light microscopy to compare decreased elastic fibers in incompetent cervices with those of normal nonpregnant and pregnant cervices. Morphologic analysis of this difference was extended to biochemical quantification of elastin content in one patient with cervical incompetence. The decrease in elastin suggests that one function of cervical elastin may be to maintain a closed and undilated cervix throughout gestation. There may be a relationship between changes in cross-linked elastin and the incompetent cervix; further studies are therefore indicated.

[Different effects of selenium on proliferation of human lung adenocarcinoma cells and human embryonic lung diploid cells in vitro]

After treating human lung adenocarcinoma cells by Na2SeO3 (1 microgram/ml) for 24 hours, its mitotic index decreased by 50%. The reduction rate was directly proportional to selenite concentration (1-5 micrograms/ml). In the meantime, the labelling index, growth rate and progression of the cell cycle were also inhibited. In contrast to the above observation, there was no marked change in the cell count, mitotic index, labelling index and the average silver granule number in the human embryonic lung diploid cells treated by Na2SeO3 (1-5 micrograms/ml) for 1-3 days. When human embryonic lung diploid cells were mix-cultured with human lung adenocarcinoma cells in the presence of 5 micrograms/ml Na2SeO3 for 24 hours, the former maintained a normal morphology, while the lung cancer cells showed heavily vacuolated cytoplasms and distorted nuclei.

Differential Effects of selenium on the proliferation of human pulmonary adenocarcinoma cells and human embryonic lung diploid cells in vitro

The effect of different concentrations of Na2SeO3 on human pulmonary adenocarcinoma cells and human embryonic lung diploid cells in vitro was investigated. For human pulmonary adenocarcinoma cells, mitotic index and cell count decreased with increasing selenium concentrations. At 1 μg/mL sodium selenite, mitotic activity and growth of human lung cancer cells were partially inhibited, and the progression of human lung cancer cell cycle was partially arrested. When human embryonic lung diploid cells were treated with 1 μg/mL sodium selenite for five continuous days, cell counts of the treated group were closely parallel to those of the control group. After treating human embryonic lung diploid cells with 1-5μg/mL sodium selenite for 1-3 d, the mitotic index (MI), labeled index (LI), and average silver grain (SG) number per 20 labeled nuclei were the same as those of the control. In mixed cultures of human embryonic lung diploid cells and human pulmonary adenocarcinoma cells, treated with 3 and 5 μg/mL sodium selenite for 24 h, the lung diploid cells showed a normal fusiform morphology, whereas the lung cancer cells showed heavily vacuolated cytoplasms and distorted nuclei.

In vitro differential effects of sodium selenite on the growth of human hepatoma cells and human embryonic liver cells

The effects of various concentrations of Na2SeO3 on human hepatoma cells and human embryonic liver cells was investigated in vitro. For human hepatoma cells, mitotic index and cell count decreased with increasing selenium concentrations. At 1 μg/mL Na2SeO3, mitotic activity of human hepatoma cells were partially arrested. In human embryonic liver cells continuously treated with Na2SeO3, (1 μg/mL) cell count of the treated group decreased only by d 7; mitotic index, labeled index, and mean silver grain number per 50 labeled nuclei were the same as in the control group on exposure to 1, 3, and 5 μg/mL for up to 72 h. In mixed cultures of human hepatoma and embryonic liver cells treated with 3 and 5 μg/mL of Na2SeO3 for 24 h, hepatoma cells showed vacuolated cytoplasms, distorted nuclei, condensed chromatin, and even pyknosis, whereas the embryonic liver cells retained a normal morphology under the same treatment.

Some differentiating effects of selenium on the cultured human hepatoma cells and human pulmonary adenocarcinoma cells in vitro

Two human hepatoma cell lines, QGY-7703 and SMMC-7721, and two human pulmonary adenocarcinoma cell lines, LTEP-a-2 and SPC-A-1, were found to respond to 1 μg/mL Na2SeO3, 24 h, in-vitro treatment by decreasing its confluent saturation density. The same treatment was found to cause an increase in the adhesiveness of cells measured as resistance to detachment by trypsin/EDTA. The pathological features of tumors after heterotransplantation of treated and untreated cells were similar, but the size of tumor grown from treated cells was much smaller.

[Mechanism of the anticancer action of selenium--influence on glycolysis and its key enzyme]

The aerobic glycolysis rate and mitochondria-bound hexokinase activity of ascitic liver cancer cells are 8 and 50 times as high as those of the normal liver cells, and they can be inhibited by Na2SeO3 in concentration below 10 micrograms/ml. The inhibitory effect increases with selenium concentration. In contrast, Na2SeO3 at the same concentration does not significantly affect the glycolysis rate and mitochondria-bound hexokinase activity of the normal liver cells. The selective action of selenium on energy metabolism of the liver cancer cells may account for its inhibitory effect on cancer cells.

Damage and repair of lung connective tissue in rats exposed to toxic levels of oxygen

We studied damage and repair of lung connective tissue in rats exposed to toxic amounts of oxygen by measuring lung content of collagen and elastin and the number of collagen fragments in lung lavage fluid after exposure to 98% O2 for 60 h. Lung collagen was decreased 17%, and collagen fragments in lavage fluid were increased 4- to 5-fold in O2-exposed rats compared with those in control rats. No biochemical evidence of elastin degradation was found. Mild emphysematous changes and a leftward shift of fluid-filled, pressure-volume curves were induced within 2 wk after recovery from exposure to O2. Administration of the lathyrogen beta-aminopropionitrile worsened the emphysematous lesion produced by hyperoxia, suggesting that replacement of connective tissue during repair limits the extent of emphysema. We conclude that lung collagen is degraded and an emphysematous lesion is produced by relatively short exposure to toxic amounts of oxygen.

Reduction of chronic hypoxic pulmonary hypertension in the rat by an inhibitor of collagen production

Chronic hypoxic pulmonary hypertension in the rat is associated with increased collagen and elastin in the pulmonary artery. We investigated whether excess vascular collagen contributes to chronic hypoxic pulmonary hypertension by administering the proline analogue cis-4-hydroxy-L-proline (cHyp), an agent relatively specific for inhibiting collagen production, to rats exposed to chronic hypoxia. Sprague-Dawley rats (weighting 200 g) were exposed to air or hypoxia (10% O2-90% N2) for 3 wk. Groups studied were: air-exposed injected with saline, air-exposed injected with cHyp, hypoxic injected with saline, and hypoxic injected with cHyp. At the end of 3 wk, we measured mean right ventricular pressure (RVP) of animals breathing room air and hydroxyproline and desmosine contents of the main pulmonary artery trunk. Hypoxia increased RVP from 13 +/- 1 to 27 +/- 1 mm Hg (p less than 0.05); cHyp partially prevented this increase since RVP was 17 +/- 1 mm Hg (p less than 0.05). There was no effect of cHyp on cardiac output. Hypoxia increased collagen from 0.9 +/- 0.1 to 2.0 +/- 0.3 mg/artery (p less than 0.05); cHyp completely prevented this increase since collagen was 1.0 +/- 0.2 mg/artery (p less than 0.05). Hypoxia increased elastin from 1.1 +/- 0.1 to 2.4 +/- 0.2 mg/artery (p less than 0.05); cHyp had no apparent effect since elastin was 2.1 +/- 0.1 mg/artery. Also, cHyp did not affect RVP or vascular collagen or elastin in air-breathing animals. The cHyp treatment prevented luminal narrowing and thickening of arteriolar walls by hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

[Mechanism of cell damage by hematoporphyrin derivatives (HPD) plus light--I. Photooxidation of hepatoma cell membrane by HPD plus light]

Ascitic hepatoma cells of mice were incubated with three HPD. After the cell-bound HPD was treated by visible light, the product of membrane lipid peroxidation--malondialdehyde (MDA) was determined. The results showed that the MDA level increased with HPD concentration and exposure time, but it was unchanged in the control. Beta-carotene, a quencher of singlet oxygen, could inhibit the lipid photooxidation of the membrane of cell-bound HPD resulting in a decrease of MDA level which decreased with increase of beta-carotene concentration. Adding vitamin E in vitro and vivo, formation of the product of membrane lipid peroxidation of cell-bound HPD by light was inhibited and the MDA level decreased with the increase of vitamin E concentration. These results show that the singlet oxygen, produced by HPD bound cells following light activation, reacts directly with the polyunsaturated fatty acids on cell membrane to produce lipid peroxides leading to cellular damage.

[Level of cyclic AMP-dependent protein kinase isozyme in normal liver and hepatoma tissue and the effect of sodium selenite]

Sodium selenite in normal saline was administered intraperitoneally (1 mg/kg) into mice bearing ascitic hepatocarcinoma for 4 days. The cyclic AMP-dependent protein kinase isozymes (type I and type II) in normal liver and hepatocarcinoma cells were separated and assayed. The results show that the level of type I/II is markedly higher in hepatocarcinoma than in the normal liver cells. Sodium selenite is able to reduce it towards the normal level. Further analysis shows that the chief function of sodium selenite is to reduce the raised level of type I/II in hepatocarcinoma cells which, in fact, is due to the increase of total amount of type I cyclic AMP-dependent protein kinase. This paper presents the speculation that one of the mechanisms of the inhibitory effect of sodium selenite on carcinogenesis may be due to the selective action of this compound on the cyclic AMP-dependent protein kinase isozymes in tumor cells, thus inhibiting cancer cell division and facilitating differentiation and reversion.

[Regional distribution of liver cancer and its relation to selenium levels in Qidong County, China]

The selenium (Se) level in barley and maize from 43 communes of Qidong county, a high risk area of liver cancer in China, were assayed. An inverse correlation between the Se level and the liver cancer incidence was observed. An inverse correlation was also observed between the blood Se level and liver cancer incidence of the local residents. When selenite solution was sprayed on the crops during their preflowering, the content of Se in barley and maize was increased by 6 fold over the control. It is suggested that the increase of blood Se level of the residents who live in the low-Se areas by this method be useful in the prevention of liver cancer.

Nutritional emphysema in the rat. Influence of protein depletion and impaired lung growth

Emphysema is produced by severe food restriction in rats and is postulated to result from depletion of lung connective tissue. We studied (1) whether total dietary protein depletion worsens nutritional emphysema, and (2) whether the reduced content of lung connective tissue in nutritional emphysema results from lack of accumulation caused by impaired lung growth or by a net loss from the lung. Lewis rats weighing 200 g were restricted to one third food intake with or without protein for 6 wk. Lungs were assessed by morphometry, pressure-volume (P-V) measurements, and content of collagen and elastin. Emphysema was found by morphometry (but not by P-V measurements) in food-restricted rats, and contrary to expectation, emphysema was less severe in those depleted of protein. Collagen and elastin content were reduced in emphysematous lungs; however, the levels were not below those found prior to nutritional intervention, suggesting that lack of growth, not depletion, accounts for the reduced content.

Regional variation of cancer mortality incidence and its relation to selenium levels in China

The epidemiological relationship between selenium level and age-adjusted human cancer mortality (incidence) was studied in 24 regions located in eight provinces of China. Statistically significant inverse correlation was found between age-adjusted total cancer death rates and selenium levels in whole blood from local residents. In the areas with high selenium levels, there was significantly lower mortality in both males and females from cancer of the stomach and esophagus. In addition, an inverse correlation between regional distribution of liver cancer incidence and selenium contents in blood and grains in Qidong county, an area with high risk of hepatoma, was observed. With the intention of providing selenium supplements to residents living in low selenium regions, the selenium content in grains was raised by means of foliar spraying of crops with Na2SeO3 solution.

Effect of proline analogs on oxygen toxicity-induced pulmonary fibrosis in the rat

Proline analogs inhibit collagen biosynthesis and prevent accumulation of collagen in tissues. The antifibrotic effects of three proline analogs, cis-hydroxyproline, L-azetidine-2-carboxylic acid, and L-3,4-dehydroproline, were compared in a rat oxygen toxicity model. The specificity of these agents for collagen was examined by measuring their effects on noncollagen protein and elastin accumulation in the lung. Increased lung collagen was produced by exposing rats to 95% O2 for 60 hr followed by a 2-week recovery period. Animals were treated with the proline analogs for the 2-week period. Oxygen exposure in untreated animals increased lung collagen 26% above air-breathing controls, and this increase was prevented by all three analogs. Increased noncollagen protein was also prevented by these agents, suggesting they were not entirely specific for collagen. Elastin accumulation, however, was not inhibited by cis-hydroxyproline. It was concluded that proline analogs were antifibrotic, but affected the metabolism of noncollagen protein.

Blood selenium concentration in residents of areas in China having a high incidence of lung cancer

Data concerning the blood selenium level and its relation to the mortality from lung cancer are reported. There were 353 samples of blood collected from workers at the Yannan Tin Mine (Yun-Xi) and 75 samples from Beijing residents for comparison. An inverse correlation between blood selenium levels and lung cancer mortalities was observed. The average selenium concentration in whole blood from Beijing residents (age-adjusted mortality rate from lung cancer for males: 12/100,000) and Yun-Xi miners (age-adjusted mortalty from lung cancer for males: 108/100,000) were 12.3 and 8.8 μg/100 mL, respectively. A similar inverse correlation was also observed among young people of comparable sex and age groups. In Yun-Xi, the tin miners working underground with an average lung cancer death rate of 250/100, 000 for males had lower blood selenium concentrations than those working above ground, where the average lung cancer death rate for males was 42/100,000. Workers frequently exposed to arsenic exhibited lower blood selenium contents. Selenium levels in the blood of patients with lung cancer were lower (6.2 μg/100 mL) than those of healthy controls.

Elevation of histidinoalanine in calcified human aortas

The cross-links histidinoalanine (HA); pyridinoline (Pyr); desmosine (Des); and isodesmosine (Ides) in human atherosclerotic aortas were studied. Only HA showed a significant increase in calcified aortas, with a high concentration in the insoluble "mineralized" fraction, which was separated out after treatment of tissues with pronase E. The cross-links composition was similar among "mineralized" fractions prepared from tissues of varying degrees of calcification: values were 2.40; 0.10; 0.17; and 0.16 moles per 1000 moles of amino acid residues for HA; Pyr; Des; and Ides, respectively. The findings suggest that the HA-containing peptide may play an important role in the calcification process of aortic tissues.

Evaluation of the Urinary Desmosine Radioimmunoassay as a Monitor of Lung Injury after Endobronchial Elastase Instillation in Sheep

Thirty male sheep were treated with varying doses of endobronchial elastase. Urinary excretion of elastin peptides was then measured by desmosine radioimmunoassay and compared with pre-enzyme values. Mean linear intercepts were measured in treated and untreated lobes 4 wk later, and in addition, lung perfusion, ventilation, and volume were measured before enzyme treatment and 4 wk later using radionuclide-imaging techniques. Most of the elevation in urinary desmosine excretion occurred in the first 48 h after elastase administration. The increase in desmosine excretion was positively correlated with: enzyme dose (r = 0.74, p less than 0.01), increase in mean linear intercept (r = 0.61, p less than 0.05), decrease in lung perfusion (r = 0.77, p less than 0.01), and decrease in ventilation (r = 0.58, p less than 0.05). These results demonstrate that the urinary desmosine radioimmunoassay is a reliable index of pulmonary elastin breakdown and of several resultant anatomic and physiologic stigmata of pulmonary emphysema.

Peplomycin sulfate and pulmonary fibrosis: hydroxyproline, uronic acid, proline hydroxylase and glucosamine 6-phosphate synthetase in lungs of hamsters treated with peplomycin

Effect of peplomycin sulfate (PLM) on pulmonary fibrosis was examined. Hydroxyproline, uronic acid, proline hydroxylase (EC 1.14.11.2) and glucosamine 6-phosphate synthetase (EC 2.6.1.16) in lungs of hamsters treated with PLM were studied and compared with those of hamsters treated with bleomycin (BLM). PLM, when administered intraperitoneally, one injection daily for 10 consecutive days, at either a high- (5 mg/kg) or low- (2.8 mg/kg) dosage-level, caused no significant increase of lung hydroxyproline and uronic acid as compared with controls. BLM on the other hand effected a significant increase in lung hydroxyproline on the high-dosage level (5 mg/kg) but not on the low-dosage level (2.8 mg/kg). In contrast, when administering PLM intratracheally, the concentrations of hydroxyproline in lungs increased 20% over the control levels. A transient increase of proline hydroxylase and glucosamine 6-phosphate synthetase also occurred shortly after the instillation. These increases were also observed in the corresponding groups treated with BLM, which confirmed the previous observations by other investigators. However, the magnitude of the increase was relatively lower in those values of PLM as compared with those of BLM. These data suggested that (1) PLM, when administered with multiple dosages intraperitoneally, showed no significant effect on the elevation of lung hydroxyproline; (2) PLM, when administered with a dose intratracheally, induced pulmonary fibrosis similar to that caused by BLM. However, the hydroxyproline accumulation in lungs of PLM-treated hamsters was less than in those of the BLM-treated; (3) The fibrotic effect on the lungs caused by either PLM or BLM was probably attributed to acceleration of the syntheses of collagen and acidic glycosaminoglycans.

Different effects of selenium on cyclic AMP metabolism in hepatoma cells and normal liver cells

Sodium selenite administered to normal and hepatoma (HA)-bearing mice sc (2 mg/kg) or ip (1 mg/kg) led to a significant increase in cyclic AMP (cAMP) level and a decrease in cAMP phosphodiesterase (PDE) activity in HA cells. In contrast, in tumor host liver and normal liver the cAMP level was reduced, and the PDE activity was slightly elevated, whereas the cAMP adenylate cyclase (AC) was little affected by Na2SeO3, if at all. These results imply that selenite-induced changes in PDE activity play a decisive role in regulating intracellular cAMP level. Kinetic studies revealed that there were different forms of PDE. TheK m value of PDE isozymes in normal liver and host liver were identical, but differed from those of HA. It seems likely that the selective responsiveness of PDE to selenite may be related to the difference in PDE isozyme patterns. Addition of DBcAMP to the culture medium resulted in an inhibition of(3)H-thymidine incorporation into hepatoma cells, indicating that the inhibition of HA cell proliferation was cAMP-mediated. Thus, selenium has been shown to exert a selective effect on cAMP metabolism of hepatoma cells, which may account for its inhibitory effects on cancer cells.

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.

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.

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.

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.

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.