Elastase binding capacity of alpha 2-macroglobulin and its association with glucocorticoid concentration in southern African black patients with hepatocellular carcinoma.

Thirty-three Southern African black patients with hepatocellular carcinoma (HCC) (7 women) and 43 black control individuals (14 women), all in the age group 18-45 years, were investigated for plasma alpha 2-macroglobulin (alpha 2M) elastase binding capacity (EBC). Cortisol levels were measured in 15 (3 women) of the HCC patients and 10 (5 women) of the control subjects. A significant difference in EBC was found between the HCC patients and the control subjects (P < 0.001). A significant difference was also found in cortisol levels between the two groups (P < 0.001). A significant correlation between EBC and cortisol levels was obtained (r = 0.57; P < 0.042). The significant increase in EBC of alpha 2M in HCC patients could be due to an increase in circulating cortisol.

Ethnic differences in the occurrence of the M1(ala213) haplotype of alpha-1-antitrypsin in asthmatic and non-asthmatic black and white South Africans.

An ethnic study of 175 individuals, comprising 65 black and 110 white South Africans, has shown a conclusive difference in the frequency of the M1(ala213) haplotype of alpha 1-antitrypsin (P < 0.00001). The M1(ala213) haplotype occurred more frequently in the black group. In the latter group, the frequency of the M1(ala213) haplotype was the same in both controls (0.55) and asthmatics (0.53). However, there was a significant difference in the frequencies (0.19 and 0.36) for the respective white groups (P < 0.01), the frequency of the M1(ala213) haplotype being much higher in the asthmatics. Apart from the above differences, there was also a difference in the elastase-inhibitory capacities of the homozygote phenotypes M1(val213) vs M1(ala213) (P < 0.0001), this capacity being lower in the latter phenotype. We conclude that the occurrence of the M1(ala213) allele of alpha 1-antitrypsin differs in various ethnic groups and may play a role in asthma.

The transport of aluminum and water across the rat small intestine.

Aluminum transport across the epithelium of the rat small intestine has been investigated to determine factors affecting its absorption and its effect on the transport of other substances across the membrane. The intestines were attached to a perfusion apparatus and perfused with Krebs-Ringer-bicarbonate buffer containing aluminum. The transport of aluminum and buffer ions across the small intestine were measured. Phosphate transport was found to be the most satisfactory marker for viability. It is impossible to accurately measure the aluminum transport across a biological membrane unless the aluminum concentration of the solution is stable over the period of measurement. Hence, the solutions were stabilized with citrate ions which made them stable over a period of at least two hours. The velocity of transport of aluminum across the epithelium increased steadily and only became constant after about one hour. The steady state value of 0.12 micrograms atom of Al/hr/mg dry tissue compares well with that reported in the literature for stable aluminum solutions. Aluminum inhibited the transport of water across the membrane, but the inhibition took about two hours to reach a steady state of about 50% of the control value. This indicates that aluminum-containing medications and foods are able to interfere with the absorption of nutrients from the gut. Aluminum salts may therefore be useful to prevent rapid dehydration in the treatment of certain diseases such as cholera.

Differences in elastase-binding activity of alpha 1-protease inhibitor and alpha 2-macroglobulin for asthma patients and control subjects with various alpha 1-protease inhibitor phenotypes.

Forty-two adult patients with asthma and 30 control subjects were investigated for elastase-binding capacities of alpha 1-protease inhibitor and alpha 2-macroglobulin in plasma. The binding activities of alpha 1-protease inhibitor and alpha 2-macroglobulin in asthmatic patients with the M phenotype for the alpha 1-protease inhibitor differed in their relationship to the values in control subjects with the same phenotype [less alpha 1-protease inhibitor for asthmatics (35.1 +/- 1.8) than for controls (42.9 +/- 2.0 kU/L) (P < 0.001); more alpha 2-macroglobulin for asthmatics (6.9 +/- 0.3) than for control subjects (5.9 +/- 0.4 kU/L) (P < 0.03)]. In contrast, the patients with a deficiency allele (S, V, or Z) for alpha 1-protease inhibitor had lower activities of both alpha 1-protease inhibitor [22.1 +/- 0.1 vs 42.9 +/- 2.0 kU/L (P < 0.001)] and alpha 2-macroglobulin [4.6 +/- 0.6 vs 5.9 +/- 0.4 kU/L (P < 0.001)] than did the control subjects with the M phenotypes. The relevance of the results to the pathogenesis of asthma is discussed.

Alpha-1-protease inhibitor in bronchial asthma: phenotypes and biochemical characteristics.

The prevalence of the different phenotypes of alpha 1-protease inhibitor (alpha 1PI) was investigated in a group of 90 asthmatic patients and compared with that of a control group of 240 individuals representing the general population. The M2M2 phenotype occurred more frequently in the asthmatic group (p = 0.015). Plasma samples of 51 of the asthmatic patients randomly selected from the different phenotype groups identified were studied for the absolute plasma values of alpha 1-PI and the inhibitory capacity of plasma for porcine pancreatic elastase, and compared with those from 21 nonasthmatic individuals of the M1M1 phenotype. Although the asthmatic patients had higher absolute alpha 1PI values (p = 0.04), the plasma elastase inhibitory capacity was markedly reduced compared with the nonasthmatic subjects (p = 0.01). The functional efficiency of alpha 1PI from asthmatic patients of the M1M1, M1M2, and M2M2 phenotypes was significantly decreased compared with that of the nonasthmatic M1M1 individuals. Functional deficiency of alpha 1PI may be important in the pathogenesis of the inflammatory process that characterizes bronchial asthma.

Deposition of aluminium in tissues of rabbits exposed to inhalation of low concentrations of Al2O3 dust.

With strong evidence coming to light for the toxicity of aluminium (Al), especially to the brain, investigation into the effects of inhalation of low concentrations of Al dust in animal models has become important. This study follows up previous observations on the effects of Al on the concentrations of essential metals in serum of workers exposed to inhalation of low concentrations of Al dust, with a study of the concentrations of Al in tissues of rabbits exposed to Al dust at one twentieth of the threshold limit value (TLV). Even at this low concentration, the amount of Al in the brains of these animals was nearly two and a half times as high as that of the control animals. The concentrations in other tissues were similar to normal. At the same time, the concentrations of Al in the serum was only slightly raised, indicating that this variable is a poor marker for the effects of Al on the body. It is suggested that an extensive study is needed to determine a more correct TLV and health based permissible concentration for occupational exposure to Al.

The effect of exposure to aluminium on concentrations of essential metals in serum of foundry workers.

The concentrations of aluminium (Al) in serum and urine of 33 volunteers exposed to inhalation of Al2O3 dust at a concentration in the air of less than 1 mg Al/m3 were measured. These were compared with results from 20 normal subjects not exposed. The concentrations of copper (Cu), zinc (Zn), and total iron (Fe) in serum were also measured. The Al concentration in serum was significantly raised in the subjects exposed to dust, but Al concentrations in urine showed no significant difference from controls. This suggests a possible change in distribution of metals in the body tissues due to the presence of Al, with incomplete excretion of Al in the urine. This redistribution was selective, as the serum concentrations of Cu were conclusively decreased whereas the serum concentrations of Zn were conclusively increased. The serum concentration of Fe did not change significantly.

Elastase binding capacity of alpha 2-macroglobulin in plasma of patients with asthma or chronic obstructive pulmonary disease, without alpha 1-protease inhibitor deficiency.

The amidolytic activity of alpha 2-macroglobulin complexed with porcine pancreatic elastase (EC 3.4.21.11) was assayed using succinyl-trialanyl-p-nitroanilide. The levels of activity were compared in chronic obstructive pulmonary disease patients, asthma patients, and in healthy subjects with no record of lung disease. Levels of alpha 1-protease inhibitor were also determined and only those cases within the normal range for alpha 1-protease inhibitor were selected. Both the asthma cases and those with chronic obstructive pulmonary disease had levels of elastase-binding capacity related to alpha 2-macroglobulin which were significantly higher than the control groups.

Functional and immunological concentrations of alpha 2-macroglobulin compared in plasma of subjects without alpha 1-protease inhibitor deficiency.

Alpha 2-Macroglobulin concentrations as measured by a functional assay and by laser nephelometry with antibody precipitation were compared for 67 outpatients at a respiratory clinic and 30 blood-donor control subjects with no respiratory disease. In both groups, concentrations of alpha 1-protease inhibitor in plasma, as measured by laser nephelometry, were within the normal reference interval. A reasonable correlation (r = 0.70) was obtained between results of functional assays and of laser nephelometry for the control individuals. For patients with pulmonary disease the correlation between the two assay methods was poorer (r = 0.53). We conclude that the functional assay of plasma is the better method for detecting abnormal concentrations of alpha 2-macroglobulin in patients with lung diseases.

Functional levels of alpha 2-macroglobulin in plasma in relation to emphysema.

In most studies, concentrations of alpha 2-macroglobulin are determined by immunological techniques. In this study, the amidolytic activity of porcine pancreatic elastase complexed with alpha 2-macroglobulin was measured using an elastase-specific substrate, succinyl-trialanyl-p-nitroanilide. The activities of plasmas from 47 emphysema cases were compared with 39 normal subjects. The age ranges of both groups were from 50 to 84 years. The mean activity of bound elastase in emphysema cases was 2.48 +/- 0.03 kU/l of plasma. The mean for normal subjects was 1.48 +/- 0.11 kU/l of plasma. The difference was very significant (2P less than 0.001). All except 2 of the emphysema cases had smoked. The same results were obtained when only people who had smoked for 25 years or more were included in the analysis. All the plasma samples of people included in the study were assayed by an immunological method for absolute level (in g/l) of alpha 1-proteinase inhibitor. The levels of alpha 1-proteinase inhibitor for all the persons studied fell within the normal range for MM-phenotypes (2 to 4 g/l).

Crocidolite-induced lipid peroxidation. II. Role of antioxidants.

Asbestos fibers in vitro produce lipid peroxidation in rat lung microsomes. Butylated hydroxytoluene prevented this peroxidation. Ascorbate in low concentrations enhanced peroxidation of lipids but inhibited it at concentrations above 4 mmole/liter so that it partially protected membrane lipids from peroxidation produced by asbestos fibers. Reduced glutathione added to microsomes gave increased peroxidation at increased concentrations up to 20 mmol/liter. At 40 mmol/liter peroxidation was prevented. Glutathione had no obvious effect on the level of peroxidation produced by asbestos fibers. The 105,000g supernatant cell fraction added either with or without glutathione gave a decrease in the amount of lipid peroxidation produced by asbestos fibers. The protective action of these reducing agents suggests a possible use as prophylactic agents against the harmful effects of inhaled asbestos.

Elevated glutamic acid values in a malnourished patient. A case report.

Routine serum and cerebrospinal (CSF) amino acid estimations were carried out on a patient with pellagra and malnutrition. Urea levels were low and serum and CSF ammonia levels elevated. A remarkable observation was that the serum glutamic acid level rose to 44.9 times normal, which is far higher than any value reported in the medical literature. At this stage no explanation for this rise is known. Similarly no explanation can be given for the posttreatment elevation of the CSF proline levels to 13.8 times above normal.

Crocidolite-induced lipid peroxidation in rat lung microsomes. I. Role of different ions.

Lipid peroxidation is increased by ferrous or ferric ions in rat lung microsomes both from rats pretreated with 3-methylcholanthrene and from untreated controls. This increase was dependent on the concentration of these ions in the reaction mixture. Crocidolite alone increased peroxidation in microsomal fractions. However, addition of ferric or ferrous ions with the crocidolite did not give a greater increase in the amount of peroxidation in microsomes. Chelation with EDTA of iron, whether originally present as free ions in the solution or attached to crocidolite, prevented lipid peroxidation. NADPH alone, when added to the microsomal fractions, did not produce any significant effect. However, when added concomitantly with crocidolite fibers, NADPH reduced the effect of crocidolite on lipid peroxidation. Magnesium, manganese, and calcium ions did not produce any significant effect on lipid peroxidation in the presence or absence of crocidolite. A reduced pH enhanced the rate of lipid peroxidation in line with increased solubility of iron salts at these pH values. All the above observations, taken together, lead to the conclusion that it is the iron in the crocidolite that is responsible for the latter's ability to enhance lipid peroxidation.

Determination of functional activity of alpha 1-protease inhibitor and alpha 2-macroglobulin in human plasma using elastase.

The competitive binding of human alpha 1-antitrypsin and human alpha 2-macroglobulin to porcine pancreatic elastase was studied. Mixtures of these two protease inhibitors, when titrated against elastase give inhibition curves analogous to those obtained with human plasma. This is however not the case when the individual inhibitors are used. A theoretical treatment enabled us to devise an assay method to determine the amounts of functional activity of alpha 1-protease inhibitor and alpha 2-macroglobulin respectively in human plasma.

Erythrocyte pyrimidine-5'-nucleotidase activity as a sensitive indicator of lead exposure.

Since the red cell enzyme pyrimidine-5'-nucleotidase (PN) is inhibited by lead, we examined the feasibility of using the activity of this enzyme as a measure of lead exposure. Erythrocyte PN activity was measured in 110 blood samples obtained from subjects working in industries which utilize lead and 40 control subjects. The measurements were then compared with a number of traditional indices of lead poisoning. These included blood and urine lead concentrations and free erythrocyte protoporphyrin, erythrocyte zinc protoporphyrin, urinary coproporphyrin and urinary delta-aminolaevulinic acid levels. There was a highly significant negative correlation between erythrocyte PN activity and blood lead concentration (-0,83; P less than 0,0001), which was greater than that for any of the other measurements. It was therefore concluded that erythrocyte PN activity is an excellent indicator of lead exposure.

Plasma amino acids and tissue methionine levels in fruit bats (Rousettus aegyptiacus) with nitrous oxide-induced vitamin B12 deficiency.

The effect of methylcobalamin inactivation by the gas nitrous oxide on plasma amino acid and tissue methionine levels in fruit bats (Rousettus aegyptiacus) was examined. Animals exposed to N2O-oxygen (1:1, v/v) for 90 min daily received a fruit diet with or without methionine or betaine supplements. Exposure and diets were continued for up to 17 weeks or until neurological impairment and muscular weakness was established. All the groups exposed to N2O had significantly lower liver, brain and plasma methionine concentrations except the methionine-supplemented animals which showed significantly raised levels. Plasma homocysteine, which was absent in controls, was present in all the N2O-exposed groups. Betaine supplementation resulted in reduced accumulation of homocysteine in plasma. However, plasma and liver methionine levels were only slightly increased compared with animals on the basal diet, and brain methionine levels were the lowest of all the groups studied. These results support the hypothesis that reduced methionine synthesis is an important contributor to the development of neurological impairment in this species and suggest that dietary supplementation with the methionine precursor betaine cannot replace the loss of vitamin B12-dependent methionine synthesis.

Erythrocyte zinc protoporphyrin determination for screening for lead exposure.

Free erythrocyte protoporphyrin (FEP), erythrocyte zinc protoporphyrin (EZP) and blood lead concentrations were measured in 150 male subjects, 110 of whom were employed in industries where lead exposure was possible. Eighty-seven per cent of these 110 workers had blood lead levels above the maximum safe level of 40 micrograms/dl, which suggests that the factory control of lead toxicity is inadequate. The AVIV dedicated front-face fluorometer (AVIV instruments, New Jersey, USA), which measures EZP, was evaluated as a simple, rapid method of screening for lead accumulation. EZP concentrations agreed well with conventional estimations of FEP (r = 0,987, P less than 0,0001), and both correlated well with the blood lead concentration (r = 0,558, P less than 0,0001 for EZP; r = 0,633, P less than 0,0001 for FEP). The specificity of the EZP level as a screening test was found to be high (98%) and the sensitivity moderately good (83%). In view of the ease and speed of operation of this portable fluorometer, it should prove useful as an aid to the detection of early lead intoxication.