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T Berg

Publications and source records attributed to T Berg.

At least 163 records · Page 9Linked to original sources
PubMed1995

Immunohistochemical localization of rK9, an enzyme of the kallikrein gene family, in the rat ventral prostate.

The rat kallikrein family consists of multiple closely related proteins. Most of these proteins have been purified from rat submandibular gland (SMG), among them rK9, an enzyme that has a direct vasoconstrictory effect on isolated aortic rings. Recently, two members of the kallikrein family, rK8 and rK9, were also purified from rat prostate, whereas other family members were not detected in this organ. In the present study, the immunohistochemical localization of rK9 was determined in rat prostate by the indirect immunofluorescence technique with polyclonal antisera against rat SMG rK9 in the first layer. The crossreactivity pattern of the antiserum against rat prostate tissue extract was established by flat-bed isoelectrofocusing and immunoblotting. The antiserum reacted with prostate rK9 but not with prostate rK8. Specificity of the immunofluorescent staining reaction was verified by staining with the primary antiserum after addition of purified SMG or prostate rK9, or other members of the kallikrein family including prostate rK8. rK9-specific immunofluorescence was detected in the prostate ductal structures. In the distal (acinar) segments, rK9 was found in the cytoplasm as granular staining in the middle third of the cell, in the luminal cell wall, and in the secretion within the lumen. In the intermediate segments, strong rK9-specific staining was observed adhering to the luminal wall as well as abundantly within the ductal lumen.

Animals↗
PubMed1995

No effect of beta-carotene supplementation on the susceptibility of low density lipoprotein to in vitro oxidation among hypercholesterolaemic, postmenopausal women.

The effect of beta-carotene on the susceptibility of low density lipoprotein (LDL) to oxidative modification was investigated in a double-blind, randomized placebo-controlled study. Hypercholesterolaemic, postmenopausal women were given 30 mg beta-carotene per day (n = 15 subjects) or placebo capsules (n = 15 subjects) for 10 weeks. They were instructed to follow the American Heart Association Step One diet. LDL, isolated before and after treatment was subjected to copper-catalysed lipid peroxidation. There were no significant differences between LDL from the beta-carotene and placebo groups, as assessed by measuring the lag time for formation of conjugated dienes; the rate of formation and the amount of conjugated dienes formed; the amount of lipid peroxides generated; and the relative electrophoretic mobility, at baseline and after treatment. Dietary records showed that the subjects were consuming similar amounts and types of fat. No significant differences were found in the lipid composition and fatty acid pattern of LDL from the two groups. In conclusion, the results indicated that supplementation with beta-carotene in non-smoking, hypercholesterolaemic, postmenopausal women had no protective effect on the susceptibility of LDL to copper-catalysed modification in vitro.

Adult↗
PubMed1995

[Prognostic relevance of hepatitis C virus genotype for responsiveness to interferon-alpha].

The influence of hepatitis C virus (HCV)-genotypes on the responsiveness to interferon- (IFN-alpha) was studied in 116 patients with proven chronic hepatitis C. 88 of 116 (76%) patients were infected with HCV-genotype 1, 7 (6%) with HCV-genotype 2, and 21 patients (18%) with HCV-genotype 3. All patients received at least 3 MU recombinant IFN-alpha-2a, 2b or lymphoblastoid IFN-alpha tiw for at least 6 month (total IFN-alpha dose per patient 216-720 MU, mean 360; treatment duration 6-12 month, mean 8). The follow-up after cessation of therapy was 9-48 months (mean 25). Sustained normalization of the aminotransferase levels was observed in 20 (17%) of the 116 patients. 10 of the 88 (11%) patients with HCV-genotype 1, 7 of the 21 (33%) patients with HCV-genotype 3 (p < 0.02), and 3 out of the 7 patients with HCV-genotype-2- infection achieved a sustained remission. No response was observed in 58 (66%) and 3 (14%) patients with HCV-genotype 1 and 3 infections, respectively (p < 0.002). All but one of the sustained responders remained HCV-RNA negative during the entire follow-up. There were no significant differences between the sustained responders and the group of non-responders and responders with relapse in relation to age, pretreatment aminotransferase levels, histological activity index, or given IFN-alpha dosage. HCV-genotyping is helpful in evaluating the responsiveness to IFN-alpha and will be of importance considering the indication of therapy.

Adult↗
PubMed1994

Purification of enzymes of the kallikrein gene family (rK8 and rK9) from the rat prostate.

The rat kallikrein family consists of multiple closely related proteins. A method for demonstration and identification of kallikrein-like proteins has been developed based on their differences in isoelectric point and their immunological similarity. The method, which involved separation in flat-bed isoelectro-focusing gels (pH range 3-9) and detection by immunoblotting using polyclonal antiserum against one of the family members, has been used in the present study to detect kallikrein-like proteins in the rat prostate. Nine immunoreactive kallikrein-like protein bands were detected with pI ranging from 5.30 to 8.35. Of these, six were completely purified and three were partially purified. Two proteins (pI 5.30 and 6.75-6.90) corresponded to protein bands in gels of rat submandibular-gland extracts, and were identified by partial amino acid sequence analysis as rK8 and rK9 respectively. In addition, sequence analysis revealed complete sequence similarity between rK9 and the immunoreactive prostate proteins with pI 7.15, 7.25, 7.50 and 8.27. On the basis of this finding and immunological and biochemical characterization, we concluded that all the kallikrein-like proteins detected, except for rK8, represented isoenzymes of rK9. The molecular masses of the prostate rK9 isoenzymes (24,600-29,300 Da) were close to that of submandibular-gland rK9 (24,600 Da), although differences were observed after reduction with mercaptoethanol. The prostate rK9 isoenzymes were, like submandibular-gland rK9, inhibited by soya-bean trypsin inhibitor but not by aprotinin, and were classified as serine proteases as they were inhibited by phenylmethanesulphonyl fluoride. rK8 (28,700 Da) showed no activity with any of the substrates tested, and its inhibitory profile could therefore not be studied. No other enzymes of the kallikrein family were found in the rat prostate.

Amino Acid Sequence↗
PubMed1994

Effect of cholesterol feeding on the susceptibility of lipoproteins to oxidative modification.

In previous studies we have shown that the liver endothelial and Kupffer cells in hypercholesterolemic rabbits are very active in endocytosis of low-density lipoprotein (LDL) and beta-very-low-density lipoprotein (beta-VLDL) (Nenseter et al. (1992) J. Lipid Res. 33, 867-877; Gudmundsen et al. (1993) J. Lipid Res. 34, 589-600). These data raised the question whether subfractions of LDL and beta-VLDL were modified in vivo to forms recognized by the scavenger/oxidized LDL receptors of the non-parenchymal liver cells. The purpose of the present study was to address this question by assessing the effect of cholesterol feeding on the susceptibility of the lipoproteins to oxidative modification in vitro. In addition, the effect of HDL on the lipid peroxidation of LDL was evaluated. LDL and beta-VLDL were isolated from rabbits given a diet supplemented with cholesterol (2% w/w) for 3 weeks. The extent of Cu(2+)-catalyzed oxidation of the lipoproteins was compared with that of LDL from control-fed rabbits. Extent of oxidation assessed by formation of conjugated dienes, lipid peroxides, thiobarbituric acid-reactive substances, relative electrophoretic mobility and uptake of lipoproteins by J774 macrophages suggested that LDL and beta-VLDL from the hypercholesterolemic rabbits were more susceptible to oxidation than LDL from normolipidemic rabbits. HDL protected LDL and beta-VLDL from lipid peroxidation in vitro. Taken together, the increased susceptibility of LDL and beta-VLDL to oxidative modification in vitro, combined with the low levels of alpha-tocopherol, and the reduced ratio of HDL to LDL cholesterol observed in the hypercholesterolemic rabbits, and the protective effect of HDL on the lipid peroxidation of LDL, support the probability that oxidative modification of LDL and beta-VLDL occur in vivo in the hypercholesterolemic rabbits.

Animals↗
PubMed1994

Use of glycyl-L-phenylalanine 2-naphthylamide, a lysosome-disrupting cathepsin C substrate, to distinguish between lysosomes and prelysosomal endocytic vacuoles.

Lysosome-disrupting enzyme substrates have been used to distinguish between lysosomal and prelysosomal compartments along the endocytic pathway in isolated rat hepatocytes. The cells were incubated for various periods of time with 125I-labelled tyramine cellobiose (125I-TC) covalently coupled to asialoorosomucoid (AOM) (125I-TC-AOM); this molecule is internalized by receptor-mediated endocytosis and degraded in lysosomes, where the degradation products (acid-soluble, radio-labelled short peptides) accumulate, Glycyl-L-phenylalanine 2-naphthylamide (GPN) and methionine O-methyl ester (MOM), which are hydrolysed by lysosomal cathepsin C and a lysosomal esterase respectively, both diffused into hepatocytic lysosomes after electrodisruption of the cells. Intralysosomal accumulation of the hydrolysis products (amino acids) of these substrates caused osmotic lysis of more than 90% of the lysosomes, as measured by the release of acid-soluble radioactivity derived from 125I-TC-AOM degradation. The acid-soluble radioactivity coincided in sucrose-density gradients with a major peak of the lysosomal marker enzyme acid phosphatase at 1.18 g/ml; in addition a minor, presumably endosomal, acid phosphatase peak was observed around 1.14 g/ml. The major peak of acid phosphatase was almost completely released by GPN (and by MOM), while the minor peak seemed unaffected by GPN. Acid-insoluble radioactivity, presumably in endosomes, banded (after 1 h of 125I-TC-AOM uptake) as a major peak at 1.14 and a minor peak at 1.18 g/ml in sucrose gradients, and was not significantly released by GPN. GPN thus appears to be an excellent tool by which to distinguish between endosomes and lysosomes. MOM, on the other hand, released some radioactivity and acid phosphatase from endosomes as well as from lysosomes.

Animals↗
PubMed1994

Biodistributions of air-filled albumin microspheres in rats and pigs.

The air-filled microspheres of the ultrasound-contrast agent Albunex are unique in that the walls consist of human serum albumin molecules which have been made insoluble by sonication of the albumin solution. The microspheres were isolated by flotation, and the washed microspheres were labelled with 125I. The labelled material was cleared from the circulation mainly as particles, not as soluble albumin molecules. In rats, 80% of intravenously injected microspheres were cleared from the blood within 2 min. Nearly 60% of the dose was recovered in the liver, only 5% in the lungs, 9% in the spleen, and negligible quantities in kidneys, heart and brain. Of the radioactivity in the liver, more than 90% was taken up by Kupffer cells (liver macrophages). The protein in the liver was degraded apparently with first-order kinetics (half-life 40 min). In pigs, over 90% of the intravenously injected dose was recovered in the lungs. The vastly increased recovery in pig lungs, compared with that in rats, is probably due to the pulmonary intravascular macrophages of the pig; macrophages are not normally found in this location in rats (or humans). In a separate series of experiments in rats, the biodistribution of shell material from the microspheres was examined. The microspheres were made to collapse by applying external pressure on the suspension, leaving sedimentable protein material consisting of layers of insoluble albumin from the 'shells' surrounding the air bubble. The 'shells' and the microspheres were cleared from the circulation and taken up by the liver with the same kinetics. In the lungs, a higher proportion (15%) of shells than of microspheres was recovered.

Air↗
PubMed1994

Separation of lysosomes and autophagosomes by means of glycyl-phenylalanine-naphthylamide, a lysosome-disrupting cathepsin-C substrate.

In density-gradient analyses of autophagic vacuoles from isolated rat hepatocytes, autophagosomes could be recognized by the presence of an autophagically sequestered cytosolic enzyme, lactate dehydrogenase (LDH). Lysosomes were identified by marker enzymes such as acid phosphatase, or by degradation products from 125I-tyramine-cellobiose-asialoorosomucoid (125I-TC-AOM) loaded into the lysosomes by an intravenous injection in vivo 18 h prior to cell isolation. Autophagosomes and lysosomes showed similar, largely overlapping, density distributions both in hypertonic sucrose gradients and in isotonic Nycodenz gradients. As a step towards the purification of autophagosomes, we investigated the possibility of using lysosomal enzyme substrates to achieve selective destruction of lysosomes by swelling. Hepatocytes were first incubated for 2 h at 37 degrees C with vinblastine (50 microM) to obtain an accumulation of autophagosomes (to 3-5-times above the control level). The cells were then electrodisrupted and the disruptates incubated with a variety of substrates for lysosomal enzymes. Among these, glycyl-phenylalanine-2-naphthylamide (GPN), a cathepsin-C substrate, and methionine-O-methylester (MetOMe), an esterase substrate, turned out to induce extensive rupture of lysosomes, as measured by a strongly reduced sedimentability of acid phosphatase and a nearly complete loss of 125I-TC-AOM sedimentability in substrate-treated preparations from control or vinblastine-treated cells. The lysosomes of cells treated with leupeptin or asparagine were largely resistant to the action of GPN, probably as a result of interference with cathepsin-C activity or lysosomal function in general. Autophagosomes were partially destroyed by MetOMe, as indicated by a reduction in sedimentable LDH, but GPN had no effect on either autophagosomes or mitochondria. The ability of GPN to selectively destroy lysosomes without affecting the autophagosomes of vinblastine-treated cells should make GPN treatment a useful aid in the purification of rat liver autophagosomes.

Animals↗
PubMed1994

Nedocromil sodium 2% eye drops for twice-daily treatment of seasonal allergic conjunctivitis: a Swedish multicentre placebo-controlled study in children allergic to birch pollen.

This was a multicentre, double-blind, randomized group comparative study in which 77 children, aged 6-16 years, received 2% nedocromil sodium eye drops and 72 received placebo, one drop into each eye twice daily. The treatment period was 4 weeks, covering the peak birch pollen season. Prior to the start of the season, patients who had attended the clinic the previous 2 years because of seasonal allergic conjunctivitis (SAC) to birch pollen, entered a one week baseline period during which symptoms were assessed, dairy cards completed, and routine sampling of blood and urine carried out. The double-blind treatment period then commenced at the onset of the birch pollen season. Patients/parents kept daily diary record cards of eye symptom severity and concomitant therapy. Conjunctivitis was mild in both treatment groups but nedocromil sodium was more effective than placebo in controlling symptoms. During the 2-3 weeks of peak pollen counts, this therapeutic effect was statistically significant for itching (P < 0.01), watering (P < 0.05) and total symptom score (P < 0.01), but was not significant for grittiness (P = 0.08) or redness (P = 0.06). Global opinions of efficacy showed no difference between treatments, due to a high placebo effect (however, the diary card data indicated a significant improvement with nedocromil sodium). We therefore conclude that nedocromil sodium 2% eye drops, administered twice daily, is an effective treatment for SAC in children.

Adolescent↗
PubMed1994

Incidence and clinical relevance of recurrent hepatitis C infection after orthotopic liver transplantation.

From September 1988 to November 1992 318 liver transplants were performed at our hospital. Of these patients 68 had end-stage cirrhosis due to non-A, non-B, hepatitis, 44 of whom (64.7%) had hepatitis C virus RNA in the serum. Of this subgroup 35 patients (79.5%) were also anti-HCV positive. Postoperatively most recipients remained anti-HCV positive and after 1 year more than 90% had HCV RNA in the serum. About 40% developed a mild, chronic hepatitis and 50% were carriers of HCV without histopathological signs. Two patients suffered from a temporary severe acute hepatitis and one patient had a fulminant liver failure due to reinfection. In general, in liver recipients transplanted for end-stage HCV hepatitis there was a high incidence of reinfection with HCV. The clinical course, however, was less severe than in hepatitis B recurrence.

Carrier State↗
PubMed1994

The role of nitric oxide, adrenergic activation and kinin-degradation in blood pressure homeostasis following an acute kinin-induced hypotension.

1. Nitric oxide (NO) has been suggested as the mediator of the vascular response to bradykinin. In the present study, we found that NO did not mediate the hypotensive response to bradykinin. In addition, the significance of kininase II in terminating a kinin-induced hypotension and the role of the adrenergic system in compensating for the acute fall in blood pressure (BP) was established. 2. In normal rats, the NO-synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) induced a rise in basal BP (delta BP = 40 +/- 6 mmHg, P < 0.0014) which was not altered by pretreatment with phentolamine (delta BP = 50 +/- 6 mmHg, NS). L-NAME did not attenuate the acute fall in BP in response to bradykinin (3-30 micrograms kg-1) or kallikrein (6-300 micrograms kg-1). However, a significant decrease was observed in the duration of the hypotensive response (P < 0.027). This shorter duration was not observed after pretreatment with phenotolamine in addition to L-NAME. Phentolamine alone prolonged the hypotensive response to bradykinin (P < 0.04). These experiments confirm the role of NO-formation as a hypotensive component in BP homeostasis but not the role of NO as a mediator in kinin-induced hypotension. It further shows that the continuous NO-release also impedes the compensatory adrenergic hypertensive response following the acute fall in BP induced by bradykinin. 3. The hypertensive response to intravenously administered phenylephrine was found to be unchanged by preadministration of L-NAME (NS) thus showing that L-NAME did not change the sensitivity to the adrenergic response. In a separate protocol on L-NAME-treated rats we found no difference in heart rate (NS) during the recovery period following bradykinin before as compared to after administration of phentolamine. It was therefore concluded that the observed alterations in the duration of the hypotensive response were most probably due to changes in peripheral vascular resistance.4. To confirm further that NO is not a mediator in kinin-induced hypotension, we used an experimental model where the response to bradykinin was prolonged by preventing kinin degradation by kininase II-converting enzyme inhibitor (CEI). To produce a hypotensive response purely dependent on kinin, the studies were performed after removal of the renin-angiotensin system by nephrectomy (Nx). In this model, bradykinin (6 microg kg-1, i.v.) induced a prolonged hypotensive response. Pretreatment with LNAME did not alter the magnitude or the progression of the hypotensive response to bradykinin, thus confirming that NO was not a mediator in BK-induced hypotension.5. To study the mechanisms involved in terminating the hypotensive response to bradykinin, the results from the Nx CEI-treated rats were compared with Nx animals not treated with CEL. In the latter group,bradykinin induced a short hypotensive response, i.e. 0.5 +/- 0.1 min as compared to the 17 +/- 1 min after CEI (P<0.003). After kininase II-inhibition (and L-NAME), BP recovery was totally dependent on the adrenergic system, since phentolamine prevented a recovery in BP during the experimental period(P<0.01, compared to the CEI/L-NAME group). These results demonstrate the importance of kininase II as the major agent in terminating a bradykinin-induced hypotension, whereas the adrenergic system plays a small, although significant role in compensating for the fall in BP. The continuous release of NO therefore not only lowers basal BP but also impedes the compensatory adrenergic response.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1994

Extracorporeal shock wave lithotripsy of gallstones in different biles and water in vitro.

Twenty-four gallstones were fragmented by extracorporeal shock wave lithotripsy (ESWL) to compare the influence of three different biles (bovine bile, human bile, synthetic bile) and water on the rapidity of fragmentation. Four groups of comparable stones were used for lithotripsy in vitro. The stones were collected from 6 patients, four nearly identical 'sister' stones from each patient. The number of shock waves required for adequate fragmentation (fragments < or = 4 mm) was measured for comparison. Overall highly significant differences were found for the four different 'biles' with regard to the number of shock waves required for adequate fragmentation. Using synthetic bile, which was artificially composed according to a textbook on hepatology, significantly more shock waves were necessary for fragmentation compared to the use of water, bovine bile or human bile. On the other hand, no significant difference between water and human bile could be registered. We conclude that the number of shock waves required for adequate lithotripsy is influenced by the composition of bile in which the stone is fragmented. Possibly results of ESWL can be improved by manipulation of the bile.

Animals↗
PubMed1994

Physiological regulation of the secretion of histatins and statherins in human parotid saliva.

The small salivary phosphoproteins, histatins and statherins, have important functions in the oral cavity in terms of antimicrobial actions and regulation of calcium phosphate homeostasis. Neither the effects of various physiological stimuli on their secretion nor the nature of the efferent receptor involved in the stimulus-secretion coupling has been determined previously. These aspects are important for improved understanding of the secretory control of salivary proteins and may have implications regarding the effects of specific medications on salivary constituents and oral health. The effects of graded mechanical (chewing on short and long silicone tubings) and gustatory stimulation (0.5, 1.5, and 5.0% citric acid) on the secretion of histatins and statherins were studied in the presence and absence of adrenolytic agents (n = 10). In this model, secretory rates of both proteins increased with increases in flow rate, with 5.0% citric acid representing a particularly potent stimulus. Histatin and statherin secretory rates were significantly reduced by the beta 1-adrenolytic agent (histatins to 58 to 72% and statherins to 11 to 29% of that in corresponding control experiments), but not by the alpha 1-adrenolytic agent. Since the beta 1-adrenergic receptors played an important role in the stimulus-secretion coupling of these proteins, protective salivary functions in the oral cavity may be compromised during beta 1-adrenolytic treatment.

Adult↗
PubMed1994

Binding and intracellular fate of beta-very low density lipoprotein in isolated rat liver parenchymal cells.

Binding of rabbit 125I-tyramine-cellobiose-beta-very low density lipoprotein (125ITC-beta-VLDL) was saturable both in suspended and cultured rat liver parenchymal cells, and in isolated rat liver membrane fractions. The specific binding had KD values ranging from 8 to 10 micrograms/ml. At 37 degrees C beta-VLDL was internalized and degraded in parenchymal cells in culture, but only negligible degradation was measured in suspended cells. In cultured cells the degradation was inhibited by lysosomal and microtubular inhibitors, these agents had no effects in suspended cells. Studies of release suggested internalization in suspended cells and subcellular fractionation experiments confirmed that internalized 125ITC-beta-VLDL reached the lysosomal compartment in cultured cells, but not in suspended cells. Since lactosylated (lac-) beta-VLDL was taken up and degraded efficiently by suspended cells, these cells are not in general unable to transport large lipoprotein particles to the lysosomes. We believe that beta-VLDL does not dissociate from the receptor in the endosomes and therefore is retroendocytosed to the plasma membrane. In isolated parenchymal cells the beta-VLDL binding site is supposedly different from the methylamine-activated-alpha 2-macroglobulin (ma-alpha 2M) binding site, since; 1) Excess beta-VLDL did not reduce ma-alpha 2M binding; 2) In suspended parenchymal cells ma-alpha 2M was readily degraded, whereas beta-VLDL was not degraded and 3) The binding of beta-VLDL was not Ca+(+)-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Processing of epidermal growth factor in the rat submandibular gland by Kallikrein-like enzymes.

Epidermal growth factor (EGF) is synthesized as a precursor which is processed intracellularly to a 6 kDa EGF in the rat submandibular gland. This gland contains very high amounts of kallikrein-like enzymes, and the purpose of the present study was to examine whether any of five such enzymes, rK1, rK2, rK7, rK9 or rK10, can process the rat EGF precursor. Molecular weight forms of EGF, that were N- or C-terminally extended compared to submandibular gland EGF were obtained from rat urine. These extended forms of EGF were incubated with each of the enzymes for 24 h at 37 degrees C. Two enzymes, rK7 and rK10, were able to cleave N- and C-terminally extended EGF, releasing a form of EGF which eluted similarly to submandibular gland EGF upon gel filtration, and which was recognized both by antibodies against rat EGF and by the EGF receptor. One enzyme, rK1, cleaved C- but not N-terminally extended EGF. Neither rK2, nor rK9 cleaved the extended forms of EGF. In previous immunohistochemical studies rK1, rK7 and rK10 have all been demonstrated in the EGF containing cells of the rat submandibular gland. EGF and rK1 are also synthesized in the rat kidney but the present study demonstrated that EGF and rK1 are not colocalized in this organ. Based on the cleavage of the extended forms of rat EGF by rK1, rK7 and rK10 and on the fact that the enzymes are abundant and colocalized with EGF in the rat submandibular gland, we suggest that rK1, rK7 and rK10 can be involved in the processing of the EGF precursor in the rat submandibular gland.

Animals↗