Effects of tobacco smoking on alpha-2-macroglobulin and some biochemical parameters in Thai males.

This cross-sectional study was carried out among smokers and nonsmokers from suburban and urban residential areas in Bangkok, Thailand. One hundred eighty-six smokers and 102 nonsmokers, who voluntarily participated in the study, were investigated. The levels of alpha-2-macroglobulin (A2M), albumin, total protein, and other biochemical and hematological parameters as well as body mass index (BMI) measurements were taken. The levels of A2M, BUN and WBC counts were significantly higher in smokers than nonsmokers. Total protein and albumin concentrations were significantly lower in smokers than nonsmokers, but the levels of other biochemical parameters did not differ between the two groups. The relationship between BMI and median A2M levels in the smoker and nonsmoker groups showed the higher the BMI, the lower the serum A2M levels. Smokers had a higher percentage of hyperalpha-2-macroglobulinemia than nonsmokers. A2M concentrations correlated inversely with BMI, BUN, albumin, total cholesterol, triglycerides, and the quantity of cigarettes smoked for the total period of smoking (cigarette pack-years). Multiple regression analysis revealed that albumin and cigarette pack-years were the most closely related variables to A2M concentrations among smokers. These findings suggest cigarette smoking affects inflammation markers, increasing A2M and WBC and decreasing albumin. This effect may be the mechanism responsible for the development of chronic disease states associated with smoking since cigarette smoke contains many toxic compounds harmful to health.

Studies on proteases and alpha-macroglobulin activity in amphibian blood plasma.

Frog plasma effectively hydrolysed the synthetic chromogenic substrates, H-D-Glu-Gly-Arg-p-nitroanilide (S-2444), benzoyl-Ile-Glu-Gly-Arg-p-nitroanilide (S-2222) and acetyl-Ile-Glu-Gly-Arg- p-nitroanilide (S-2423), all sensitive substrates for trypsin. Moderate hydrolytic activities was observed with H-D-Phe-Pip-Arg-p-nitroanilide (S-2238, substrate for thrombin) and H-D-Pro-Phe-Arg-p-nitroanilide (S-2302, substrate for plasma kallikrein). Frog plasma contained moderate alpha-macroglobulin activity. When plasma was incubated at 37 degrees C, the macroglobulin activity decreased in a time dependent manner while only a moderate decrease in the protease activity was observed. Ten fold dilution of plasma with 0.1 M phosphate buffer, pH 7.6 prevented the inherent loss of macroglobulin activity but it had no effect on protease activity. Dye ligand chromatography of the plasma on red Sepharose revealed that bulk of alpha-macroglobulin activity along with minor proteolytic activity (S-2222 hydrolysis) was present i the washings. On the other hand, about one third of the alpha-macroglobulin activity and bulk of the protease activity was bound to the column and were eluted with 1.5 M NaCl. alpha-Macroglobulin activity in red Sepharose washings and elutions on chromatography on Sephadex G-200, was eluted in two regions with Ve/Vo value of 1.33 and 1.08, respectively.

Clearance of the alpha2 macroglobulin-tripsin complex and uptake of trypsin by perfused liver

The uptake and degradation of the alpha2macroglobulin-trypsin (alpha2m-trypsin) complex have been studied using isolated liver cells but not in the liver as a whole. We report the clearance of the complex by the isolated and exsanguinated liver of Wistar male rats, weighing 150-280 g, and compare it with that of the free enzyme. The hepatic clearance of the alpha2m-trypsin complex follows a pattern with a distribution phase followed by an elimination phase, which contrasts with that of trypsin where only the distribution phase is observed. The extraction of trypsin from the perfusate is Ca2+ -independent (156 + 14 pmol/g liver in the presence of 2.5 mM Ca2+, N = 9, versus 140 + 8 pmol/g liver in its absence, N = 7) and is not affected by 100 mM NH4Cl (152 + 7 pmol/g liver, N = 6), 100 U/ml heparin (164 + 14 p/mol/g liver, N = 5), 30 mul/ml carbon particle suspension (150 + 13 pmol/g liver, N = 7) or an acute-phase situation induced by turpentine (125 + 10 pmol/g liver, N = 6) (P>0.05, ANOVA). The hepatic clearance of the alpha2m-trypsin complex is Ca2+ -dependent (1.8 + 0.2 ml/min in the presence of Ca2+, N = 8, versus 0.6 + 0.03 ml/min in its absence, N = 4), affected by NH4Cl (<0.1 ml/min, N = 7), heparin (1.1 + 0.2 ml/min, N = 6) and the acute-phase (0.6 + 0.1 ml/min, N = 6) but bot by the carbon particle suspension (1.8 + 0.2 ml/min, N = 7). These results show that trypsin is not internalized by hepatocytes (no NH4Cl effect) or Kupffer cells (no carbon particle effect) and that the alpha2m-trypsin complex is internalized in a Ca2+ -dependent process by hepatocytes, but not by Kupffer cells, and is affected by an acute-phase reaction.

Plasma kallikrein clearance by the liver: a review

1. The liver is the main organ clearing both plasma and tissue kallikereins from the circulation. Hepatocytes are responsible for the internalization of rat plasma kallikrein (RPK) and liver cell is located on its heavy chain which is not exposed on prokallikrein. An S-type lectin accounts for the receptor-mediated endocytosis of TPK. 2. These properties of the liver are affected by pathological situations, particularly the acute-phase response to inflammation, in which the kallikrein-kinin system plays a major role. The hepatic clearance of the alfa2-macroglobulin-plasma kallikrein complex is less efficient than the clearance of the free enzyme

Further studies on proteinases and alpha 2-macroglobulin activity in diabetic plasma.

Loss of chymotrypsin binding capacity of alpha 2-macroglobulin in diabetic plasma on in vitro incubation, could be partially prevented by phenylmethyl sulphonyl fluoride and pepstatin A. Prior ten-fold dilution of plasma with 0.02 M phosphate buffer (pH 7.0) completely arrested the process. The phenomenon could not be reactivated by Ca2+, lecithin or bovine serum albumin. Diabetic plasma, like normal plasma, exhibited maximal hydrolytic activities on H-D-Pro-Phe-Arg-p-nitroanilide, H-D-Val-Leu-Arg-p-nitroanilide and H-D-Ile-Pro-Arg-p-nitroanilide. The hydrolytic activities were not significantly diminished on incubation of plasma at 37 degrees C for 12 hr, unlike alpha 2-macroglobulin activity. On gel chromatography on Sephadex G-200, part of the proteolytic activity in diabetic plasma coeluted with alpha 2-macroglobulin in the VO region. A second activity peak (absent in normal plasma) was eluted with a Ve/V0 value of 1.40. Possible role of free proteinases in diabetic plasma in the inactivation of alpha 2-macroglobulin is discussed.

Evaluation of factors predisposing to arterial thrombosis in coronary artery disease.

Estimation of antithrombin III, alpha 2 macroglobulin and alpha 1 antitrypsin in patients with stable and unstable angina and acute myocardial infarction (15 cases each) were carried out. Twenty age, sex and weight matched healthy subjects were included as controls. Mean platelet factor 4(PF4) levels measured in 10 cases of each subgroup were significantly elevated in myocardial infarction (MI) (48.4 +/- 15.16 ng/ml) and III unstable angina patients (44.7 +/- 15.9 ng/ml) as compared to controls (25.42 +/- 12.47 ng/ml; P less than 0.01). Mean antithrombin III (AT III) levels were markedly reduced in all patients with MI (39.65 +/- 12.8% of normal pooled plasma) and unstable angina (37.9 +/- 16.6% of normal pooled plasma) and in 9 patients with stable angina. Alpha I antitrypsin and alpha 2 macroglobulin levels in these cases showed no significant difference compared to normals. Reduced AT III in coronary artery disease suggests a prethrombotic tendency in these patients. Raised PF4 levels in acute phase of the disease suggests heightened platelet activation.

Effect of sex steroids on the circulating levels of alfa2-macroglobulin in injured rats

The effect of sex steroids on the plasma levels of alfa2-macroglobulin (alfa-2M) was investigated to explain the sexual dimorphism observed in response to the injuries caused by ip administration of 5 microng endotoxin. Mean serum alfa2-M concentrations were lower in female (46.82 ñ8.10 arbitrary units) than in male injured rats (82.94 ñ 9.22 arbitrary units). a reduction of plasma alfa2-M levels was observed after orchidectomy, and the administration of 1 mg testosterone to the same animals increased the response. The same response pattern wa observed in ovariectomized rats under the same treatment. The response of androgenized rats (78.93 ñ 12.81 arbitrary units) to injury was similar to the male response. These results suggest the importance of testosterone as the major determinant of this sex-dependent response