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Biomedical subjects

A Isaksson

Publications and source records attributed to A Isaksson.

At least 91 records · Page 5Linked to original sources
PubMed1991

Association between urinary N-acetyl-beta-glucosaminidase and its isoenzyme patterns and microangiopathy in type 1 diabetes mellitus.

Urinary N-acetyl-beta-glucosaminidase (NAG) and its isoenzymes (NAG A and NAG B) in samples from 87 type 1 diabetic patients and 40 apparently healthy reference subjects were studied with enzyme immunoassays. The diabetic patients had higher concentrations of urinary NAG than did the control subjects (P less than 0.01), but the isoenzyme pattern did not differ. There was a positive correlation between metabolic control (Hb A1c concentrations) and total NAG (P less than 0.01), NAG A (P less than 0.01), and NAG B (P less than 0.001). The diabetic patients were divided into three groups, depending on the degree of retinopathy. Subjects with severe forms of retinopathy did not have increased concentrations of urinary NAG unless they had concomitant nephropathy. The isoenzyme pattern was similar irrespective of degree of retinopathy or nephropathy. The results indicate that concentrations of urinary NAG are positively correlated to the degree of nephropathy, whereas there is no such correlation to the degree of retinopathy.

Acetylglucosaminidase↗
PubMed1990

Enzyme immunoassay of urinary beta-hexosaminidase isoenzymes in patients with renal transplants.

beta-Hexosaminidase (NAG) and percent of NAG B were studied in twenty patients following renal transplantation. Median urinary NAG for twenty reference individuals was 0.26 U/mmol creatinine and NAG B was 24%. Urinary NAG decreased rapidly from a median of 3.7 U/mmol on the third day, to 1.2 U/mmol on the 15th day after transplantation in the patients with no major complications. The percentage of NAG B did not change significantly during this period and did not differ from the reference population. Rejection and cyclosporine toxicity were diagnosed on 17 occasions. Urinary NAG rose more than twofold in 15 of these episodes. The percentage of NAG B was slightly increased in 6 of these. Six months after discharge 17 of the renal transplants functioned well. They exhibited a marked decrease (almost normalized) of urinary NAG with no change in the percentage of NAG B.

Adult↗
PubMed1990

The effect of excess daily methionine intake on plasma homocysteine after a methionine loading test in humans.

Impaired homocysteine metabolism might be a risk factor for vascular disease. Peroral methionine loading and post-load determination of methionine and homocysteine in plasma has frequently been used for identifying subjects with genetically impaired homocysteine metabolism. However, a methionine-rich diet induces a more efficient homocysteine catabolism in the rat, which suggests that humans on diets with differing methionine content might respond differently to the methionine loading test. To study this we performed methionine loading in six healthy subjects before and after 2 wk of excessive daily methionine intake (300% of normal). On each occasion plasma homocysteine and methionine were measured at several intervals post-load. However, neither the methionine clearance nor the post-load homocysteine concentrations were affected by excess methionine. We conclude that variations in the daily methionine intake will not influence the methionine loading test.

Adult↗
PubMed1990

Methodological approaches to immunohistochemical demonstration of beta-hexosaminidase in human placental and renal tissue with monoclonal antibodies.

The lysosomal enzyme, beta-hexosaminidase (Hex), was studied in full-term human placentas and in renal tissue using monoclonal antibodies raised against Hex purified from human placentas. The immunohistochemical reaction for Hex was pronounced in trophoblastic cells and macrophages of the basal plate and the smooth chorion, but was faint or negative in the amnion as well as in the syncytiotrophoblast and Hofbauer cells of the chorionic villi. The maternal decidual cells of the basal plate were negative. Biochemical enzyme analysis showed the highest activity in basal plate cells (containing trophoblast, decidual cells, macrophages and neutrophils) and a low activity in the chorionic villi. Placental tissue was less positive with monoclonal antibodies specific for Hex A, compared with antibodies reacting with both Hex A and Hex B. Epithelial cells of the renal proximal tubules were positive to the same degree with antibodies recognizing both Hex A and Hex B as well as those recognizing only Hex A.

Antibodies, Monoclonal↗
PubMed1990

Immunohistochemical demonstration of beta-hexosaminidase in cirrhotic and cholestatic human livers with a monoclonal antibody.

The lysosomal enzyme beta-hexosaminidase (Hex) was studied immunohistochemically with a monoclonal antibody in normal human livers and in livers with cirrhosis and cholestasis. No reaction was detected in sections from normal livers. The reaction in diseased livers was prominent mainly in degenerating hepatocytes, whereas Kupffer cells and bile duct epithelium showed faint reactivity. The reaction product was intense in degenerated hepatocytes, especially in the periphery of the pseudolobules in cirrhotic livers. In cholestatic livers the positivity was localized around central veins in cells with bile pigment. The more pigment, the stronger was the reaction. It is suggested that the elevated level of serum Hex found in cirrhosis and cholestasis derives from degenerating hepatocytes and activated Kupffer cells.

Antibodies, Monoclonal↗
PubMed1990

Enzyme release from cultured human melanoma cells.

The lysosomal enzyme beta-hexosaminidase and the melanocyte specific enzyme tyrosinase were examined in human melanoma cell cultures. The beta-hexosaminidase activity of the medium was approximately 40% of the total cellular activity after 24 h, while after 48 h the activity in the medium was twice that of the cells. The tyrosinase activity in the medium was 5% and 19% of the total cellular activity after the 24 h and 48 h incubation, respectively. The low level of lactate dehydrogenase activity in the medium after 24 as well as 48 h of incubation indicated that the release of beta-hexosaminidase and tyrosinase was not due to membrane injury. The data suggest, that 1) beta-hexosaminidase may be a candidate for tumor markers in malignant melanoma, and 2) the tyrosinase activity found in sera of melanoma patients may be due, at least partly, to enzyme release by living cancer cells.

Cell Line↗
PubMed1989

Immunoassay of beta-hexosaminidase isoenzymes in serum in patients with raised total activities.

Enzyme immunoassay (EIA) methods with monoclonal antibodies specific for beta-hexosaminidase (Hex) isoenzymes A and B in human serum are presented. The proportion of Hex A obtained with the EIA-methods was similar to that found with ion-exchange chromatography and isoelectric focusing (about 60% of total Hex activity). The EIA-method for Hex B reacted to a similar extent with Hex B, Hex P and intermediate forms. A highly significant correlation was obtained between total Hex activity in human sera assayed with a conventional enzyme substrate method and the total Hex activity obtained as the sum of Hex A and Hex B analyzed with the EIA-methods. In sera from individuals with increased total activity of Hex there was a positive correlation between total activity of Hex, and percent of Hex B found with the EIA-methods. Investigation of sera from pregnant women and sera from patients with liver cirrhosis and cholestasis showed that the increase in total activity in these patient groups was mainly due to an increase of the isoenzyme forms reacting with the EIA-method for Hex B.

Adolescent↗
PubMed1989

Determination of homocysteine in plasma by ion-exchange chromatography.

A rapid ion-exchange chromatographic method for determination of total homocysteine in plasma is presented. The method has a coefficient of variation of approximately 5%. A comparison with a slower method previously used in our laboratory showed a high correlation (r = 0.993). The risk of oxidation of homocysteine during the chromatography and the necessary level of dithiotreithol to prevent oxidation are also established.

Chromatography, Ion Exchange↗
PubMed1989

Enzyme immunoassay of beta-hexosaminidase isoenzymes using monoclonal antibodies.

Purified beta-hexosaminidase A (Hex A) and beta-hexosaminidase B (Hex B) were used as immunogens in mice, with the purpose of obtaining isoenzyme-specific monoclonal antibodies (mabs). A total of 60 mabs were developed, 23 specific for Hex A and 37 recognizing both isoenzymes. At low pH, two of the latter mabs reacted only with Hex B, and it was, therefore, possible to develop enzyme immunoassays for the specific determination of Hex A and Hex B. The precision of the methods was adequate with intra- and interassay coefficients of variation below 3%.

Animals↗
PubMed1989

Enzyme immunoassay of beta-hexosaminidase isoenzymes in human urine and renal cortex with monoclonal antibodies.

Enzyme immunoassay (EIA) methods with monoclonal antibodies specific for N-acetyl-beta-D-glucosaminidase (NAG) isoenzymes A and B in human urine are presented. The proportion of NAG B obtained with the EIA methods was similar to that found with ion-exchange chromatography. In fresh human control urines, NAG B was found to be approximately 20% of the total NAG activity. A significant correlation was obtained between total NAG activity in human urine assayed with a conventional enzyme substrate method and the total NAG activity obtained as the sum of NAG A and NAG B analyzed with the EIA methods. Total NAG activity with the latter (EIA) methods showed about 30% higher values than found by the enzyme substrate method, which probably was due to inhibitors of NAG activity present in urine did not interfere with the EIA methods. The content of NAG A and NAG B in renal cortex was determined with the EIA methods. NAG B accounted for about 20% of the total NAG activity, which was similar to that found in fresh human urines.

Acetylglucosaminidase↗
PubMed1989

Alkaline phosphatase in cholestatic and cirrhotic rats. A biochemical and histochemical study.

Alkaline phosphatase (ALP) was studied by enzyme histochemical methods and by biochemical quantitations in rat livers with chronic bile duct obstruction and experimental cirrhosis. The most evident ALP increase was histochemically found in portal tracts of rats with bile duct obstruction and localized to the walls of proliferating blood vessels. Furthermore, a slight canalicular membrane enzyme increase was histochemically found in both groups, most evident in cirrhosis, whereas the biochemical assay of ALP in serum and liver from both pathological groups showed 3 times higher values compared to controls. The portal tracts did not seem to contribute to the serum increase, since the rise of serum ALP was similar in chronic bile duct obstruction and in experimental cirrhosis without changes of the portal tracts. It is concluded that the increase ALP activity in serum from rats with bile duct obstruction and cirrhosis mainly has a hepatocytic origin.

Alkaline Phosphatase↗
PubMed1989

Urinary excretion of N-acetyl-beta-D-glucosaminidase in normal and complicated pregnancy.

The urinary excretion of N-acetyl-beta-D-glucosaminidase activity, a sensitive indicator of renal tubular injury, was monitored during and after pregnancy. During normal pregnancy, enzymuria increased progressively to levels 3-4 times above normal in the third trimester. In diabetic mothers, enzyme excretion followed a similar pattern, but was generally higher than in uncomplicated pregnancies. Also in preeclampsia, enzymuria tended to be higher than in normal pregnancy. Enzyme excretion normalized about a year after normal pregnancies, but remained elevated in diabetic subjects and in patients who had developed preeclampsia. This latter finding indicates that marginal persistent renal damage may occur during preeclampsia.

Acetylglucosaminidase↗
PubMed1988

Lysosomal enzymes in pregnant and steroid treated rats.

The contents of three lysosomal enzymes (beta-hexosaminidase, beta-glucuronidase and alpha-fucosidase) were studied in plasma and different tissues of pregnant and steroid treated rats. All these enzymes were found to be increased in plasma from pregnant rats in analogy with the findings in pregnant women. In liver tissue only beta-hexosaminidase and alpha-fucosidase were significantly increased. In rats with diethylstilbestrol (DES) and a combination of DES and progesterone, there was an increase of alpha-fucosidase in plasma and liver. No significant changes were observed for the other two enzymes. Thus, steroid treatment did not fully reproduce the enzyme changes seen in pregnancy, which may indicate that these are not solely due to a hormone effect.

Alkaline Phosphatase↗
PubMed1988

The effect of porta-caval shunt, ammonia infusion and alcohol administration on rat plasma beta-hexosaminidase.

The activity of the lysosomal enzyme, beta-hexosaminidase, is increased in plasma of patients with various forms of liver disease as well as in plasma from rats with experimental cholestasis or cirrhosis. In this experimental study in the rat, the effect of porta-caval shunt, ammonia infusion and ethanol feeding on plasma beta-hexosaminidase activity was studied. Porta-caval shunted animals had significantly increased plasma beta-hexosaminidase activity compared to sham-operated animals. Ammonia infusion in porta-caval shunted rats resulted in a further increase of plasma enzyme activity. Ethanol feeding for different periods of time (1 day to 4 weeks) did not have any influence on plasma beta-hexosaminidase activity.

Ammonia↗
PubMed1988

Source of increased serum beta-hexosaminidase in rat liver cirrhosis.

Lysosomal enzymes were studied by histo- and biochemical methods in cirrhotic rat livers in order to explain the serum increase of lysosomal enzymes in cirrhosis. Biochemically, the most evident increase was found in isolated hepatocytes. Histochemically, the lysosomal enzymes were increased mainly in rows of macrophages and necrotic or atrophic hepatocytes adjacent to strands of connective tissue at the periphery of the cirrhotic nodules. The results were compared to similar studies in cholestatic rats. It is concluded that most of the increased serum activities of the lysosomal enzymes derive from the hepatocytes.

Animals↗