Biomedical subjects

B Hultberg

Publications and source records attributed to B Hultberg.

At least 109 records · Page 6Linked to original sources

PubMed1991

Increased levels of plasma homocysteine are associated with nephropathy, but not severe retinopathy in type 1 diabetes mellitus.

The reactive vascular-injuring amino acid homocysteine was measured in plasma samples from 79 well-characterized type 1 diabetic patients and 46 control subjects. Patients with proliferative retinopathy had higher homocysteine levels (15.0 +/- 6.3 mumols l-1; mean +/- SD, p less than 0.001; n = 42) than those with progressive retinopathy during a two-year period (10.4 +/- 1.6 mumols l-1; n = 12), no or minimal retinopathy (10.7 +/- 4.3 mumols l-1; n = 25), and the control subjects (11.0 +/- 3.4 mumols l-1). Within the group of patients with proliferative retinopathy increased homocysteine levels were confined to those patients that had serum creatinine levels greater than 115 mumols l-1 and/or an albumin:creatinine clearance ratio greater than or equal to 0.02 x 10(-3) (17.0 +/- 5.9 mumols l-1; n = 23), whereas those with no or only minimal nephropathy had levels (12.1 +/- 5.5 mumols l-1; n = 18) that were not different from the control group. We conclude that neither type 1 diabetes mellitus nor diabetic retinopathy per se is associated with increased plasma homocysteine levels. In contrast, homocysteine accumulates, probably owing to reduced glomerular filtration, in diabetic patients with advanced nephropathy. This suggests that homocysteine might contribute to the accelerated development of macroangiopathy seen especially in this subgroup of diabetic patients.

Adult↗

PubMed1991

beta-hexosaminidase in cultured normal and mutant human fibroblasts: an immunohistochemical and biochemical investigation.

Fibroblasts from a genetically normal individual and mutant fibroblasts from patients with Tay-Sachs and Sandhoff's diseases were grown in vitro. The lysosomal enzyme beta-hexosaminidase (Hex) was determined biochemically and localized with monoclonal antibodies recognizing Hex A, and Hex A and Hex B, respectively. The biochemical results showed similar amounts of Hex A and Hex B in the normal fibroblasts, whereas only Hex B activity was detectable in the fibroblasts from the patient with Tay-Sachs disease. The fibroblasts from the patient with Sandhoff's disease showed small amounts of Hex A- and no Hex B activity. Immunohistochemically, Hex was detectable with both antibodies in the normal fibroblasts and in those from the patient with Tay-Sachs disease. The fibroblasts from the patient with Sandhoff's disease were reactive only with Hex A-specific antibody.

Cell Line↗

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

Impaired homocysteine metabolism in early-onset cerebral and peripheral occlusive arterial disease. Effects of pyridoxine and folic acid treatment.

Severe homocysteinemia due to genetic defects either of pyridoxal 5-phosphate (PLP)-dependent cystathionine beta-synthase (CBS) or of enzymes in vitamin B12 and folate metabolism is associated with very early-onset vascular disease. Therefore, we studied homocysteine metabolism in 72 patients presenting before the age of 55 years with occlusive arterial disease of cerebral, carotid, or aorto-iliac vessels. Twenty patients (28%) had basal homocysteinemia; and 26 patients (36%) had abnormal increases of plasma homocysteine after peroral methionine loading, which exceeded the highest value for 46 comparable controls and was within the range for 20 obligate heterozygotes for homocystinuria due to CBS deficiency. Basal plasma homocysteine content was strongly and negatively correlated to vitamin B12 and folate concentrations. Plasma PLP was depressed in most patients but there was no correlation between PLP and homocysteine values. In 20 patients, treatment with pyridoxine hydrochloride (240 mg/day) and folic acid (10 mg/day) reduced fasting homocysteine after 4 weeks by a mean of 53%, and methionine response by a mean of 39%. These data show that a substantial proportion of patients with early-onset vascular disease have impaired homocysteine metabolism, which may contribute to vascular disease, and that the impaired metabolism can be improved easily and without side effects.

Adult↗

PubMed1990

Glomerular filtration rate and tubular involvement during acute disease and convalescence in patients with nephropathia epidemica.

Glomerular filtration rate (GFR) and tubular involvement were studied in 74 patients with serologically verified nephropathia epidemica (NE). Increased levels of serum creatinine and serum beta 2-microglobulin were documented in 96% and 99% of the patients, respectively. The mean of the lowest estimated GFR was 26 ml/min. Proximal tubular reabsorptive capacity was assessed by urinary loss of beta 2-microglobulin and cell damage by urinary activity of N-acetyl-beta-D-glucosaminidase. Both of these parameters were elevated in most of the patients during the acute phase of the disease. Increased serum levels of Tamm-Horsfall-specific IgG and/or IgA occurred in 72 of 74 patients. No patient required dialysis and there was no mortality. Six months after discharge only three patients had a GFR less than 80 ml/min as estimated by [51Cr]EDTA clearance; two of these had underlying chronic diseases and one had suffered clinically severe NE. Desmopressin tests showed decreased urine osmolarity in three patients 8 months after discharge. These three had chronic diseases, which may have contributed to the impaired tubular function. Thus, there was a markedly decreased GFR and a tubular dysfunction in the acute phase of NE. Most patients recovered within a few months and none showed evidence of chronically impaired renal function due to NE.

Acetylglucosaminidase↗

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

The effects of ammonia tolerance tests on the cerebrospinal fluid concentrations of amino acids and indoleamines in patients with liver cirrhosis.

To study the effect of ammonia administration on amino acids and indoleamines in cerebrospinal fluid (CSF) and on amino acids, insulin, and glucagon in plasma in humans with liver cirrhosis, we performed seven ammonia tolerance tests on six patients with stable liver cirrhosis. The grade of encephalopathy was determined by psychometric tests. Only one of the patients had pronounced encephalopathy. The other patients had no or only slight encephalopathy. The plasma concentrations of valine, leucine, isoleucine, phenylalanine, tyrosine, and methionine decreased after the ammonia load, whereas no changes were found in the plasma concentrations of glucagon and insulin. In CSF the concentrations of glutamine, aromatic amino acids, and indoleamines increased only in the patient who had pronounced encephalopathy, whereas no changes were found in the other patients. The effect of an ammonia load on the concentrations of neutral amino acids in CSF in patients with pronounced encephalopathy remains to be demonstrated.

5-Hydroxytryptophan↗

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

Homocysteine, factor VII and antithrombin III in subjects with different gene dosage for cystathionine beta-synthase.

Cystathionine beta-synthase deficiency results in severe homocysteinaemia, precocious arteriosclerosis and frequent thromboembolism. In addition, antithrombin III activity and factor VII are low. Arteriosclerosis seems to be increased in heterozygotes as well (cystathionine beta-synthase gene dosage 50%) but rare in Down syndrome (cystathionine beta-synthase gene dosage 150%). In the present study total plasma homocysteine was high in three homozygotes, slightly increased in 20 obligate heterozygotes but not reduced in nine subjects with Down syndrome when compared to controls. After methionine loading, increases of homocysteine were pathologically high in 14 of 20 heterozygotes but was not, as expected, low in subjects with Down syndrome. Antithrombin III activity and factor VII antigen tended to be low in homozygotes but were normal in heterozygotes. In Down syndrome antithrombin III activity was reduced and factor VII antigen normal. There were no correlations between levels of homocysteine, antithrombin III activity and factor VII antigen. Thus, subjects with Down syndrome seem not to exhibit the expected gene dosage effect on homocysteine metabolism which could explain their reduced proneness to develop arteriosclerosis, nor do antithrombin III activity or factor VII antigen seem to be related to homocysteine metabolism.

Antithrombin III↗

PubMed1989

The effect of ammonia infusion on brain monoamine metabolism in portacaval-shunted rats.

The effect of ammonia infusion on monoamine metabolism was studied in the rat brain. Seven days after portocaval shunt (PCS) or sham operation animals were infused with ammonia or saline. Brain metabolism of serotonin and norepinephrine was studied after injection of a decarboxylase inhibitor (m-hydroxybenzylhydrazine, NSD 1015) which blocks the conversion of 5-hydroxytryptophan to serotonin and dihydroxyphenylalanine to dopamine. Neurologic testing was conducted before killing. Plasma and brain amino acids were measured. PCS animals infused with ammonia were in deep coma after 6 h infusion, whereas sham-operated animals were virtually unaffected. Brain amino acid analyses demonstrated increased concentrations of the aromatic amino acids and a tenfold increase in glutamine. Serotonin metabolism was diminished after 6 h. Dopamine synthesis was normal, but norepinephrine levels were low after 6h. The study suggests that hyperammonemia in PCS rats results in a depression of the serotonin synthesis rate in accordance with two previous studies but in contrast to previous hypotheses on the regulation of serotonin metabolism.

5-Hydroxytryptophan↗

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

Acute ischemic liver failure in the rat: a reproducible model not requiring portal decompression.

We report a model of acute ischemic liver failure which does not require temporary or permanent portal decompression. The model is induced by segmental ischemia of the median and left lateral lobes for 100 min by a vascular clamp applied on the afferent vessels. Declamping is followed by resection of the nonischemic right lateral and caudate lobes. No portal stasis occurs as blood flow to the right lateral and caudate lobes is maintained during the period of clamping. The 24-hour mortality is 76.5%. Evidence of severe liver damage is shown by histological and biochemical studies.

Acute Disease↗

PubMed1989

Thioacetamide- and carbon tetrachloride-induced liver cirrhosis.

Two methods of inducing liver cirrhosis in the rat were studied. Intragastric administration of CCl4 for 16 weeks according to Proctor and Chatamra was compared to the administration of thioacetamide in the drinking water (0.3 g/l) for the same period. CCl4 administration induced micronodular cirrhosis in 6/8 animals with a 27% mortality. Thioacetamide induced cirrhosis in 6/8 animals without mortality. The histologic pictures differed somewhat in that the CCl4 group exhibited more necrosis and cellular swelling while the thioacetamide group had more nuclear atypias and proliferation. Biochemically both groups had elevated plasma levels of aspartate aminotransferase. The lysosomal enzyme beta-hexosaminidase (beta-NAG) showed a transient increase in the thioacetamide animals, while beta-glucuronidase decreased. CCl4-induced cirrhosis led to an increase in beta-NAG. Plasma zinc decreased in both groups as well as liver zinc content in the CCl4 group, while there was a continuous elevation of liver zinc in the thioacetamide group. We conclude that oral administration of thioacetamide is a simple and reliable method of inducing experimental liver cirrhosis. The differences in histological appearances and some biochemical parameters may be caused by the different mechanisms of action of thioacetamide and CCl4.

Acetamides↗