Biomedical subjects

B M Frey

Publications and source records attributed to B M Frey.

At least 37 records · Page 2Linked to original sources

PubMed1998

Adenovector-mediated expression of human thrombopoietin cDNA in immune-compromised mice: insights into the pathophysiology of osteomyelofibrosis.

Thrombopoietin (TPO) cDNA can be effectively delivered in vivo by adenovectors. Immune normal mice (BALB/c) and syngeneic mice with variable degrees of immune dysfunction nu, SCID, and NOD-SCID) were treated with an adenovirus vector expressing the human TPO cDNA (AdTPO). Platelet peaks were significantly higher in SCID and NOD-SCID mice compared with BALB/c and nu mice. Human plasma TPO concentration correlated with the platelet counts. SCID and NOD-SCID mice exhibited also granulocytosis and increased numbers of hemopoietic progenitors in bone marrow. Following platelet peak, BALB/c mice developed autoantibodies against murine TPO leading to thrombocytopenia and depletion of megakaryocytes and hemopoietic progenitors in bone marrow. AdTPO-treated SCID mice developed osteomyelofibrosis and extramedullary/extrasplenal hemopoiesis. In contrast, NOD-SCID mice with a similar magnitude of TPO overexpression did not show fibrotic changes in bone marrow. We conclude, first, that a chronic high level of TPO overexpression stimulates megakaryocytopoiesis and myelopoiesis leading to thrombocytosis and granulocytosis. Second, increased megakaryocytopoiesis is not sufficient for development of secondary osteomyelofibrosis. The functionally deficient monocytes and macrophages of NOD-SCID mice probably prevented fibrotic marrow changes. Third, immune deficiency enhances expression of adenovirally mediated transgenes, and fourth, xenogeneic transgene delivered by adenovector to a host with normal immune functions may induce loss of immune tolerance and autoimmune phenomenon.

Adenoviruses, Human↗

PubMed1998

Down-regulation of hepatic and renal 11 beta-hydroxysteroid dehydrogenase in rats with liver cirrhosis.

BACKGROUND & AIMS: 11 beta-Hydroxysteroid dehydrogenase (11 beta-OHSD) enzymes are responsible for the interconversion of active 11 beta-hydroxycorticosteroids into inactive 11-ketoglucocorticosteroids and by that mechanism regulate the intracellular access of the steroids to the cognate receptor. A down-regulation of the shuttle of active to inactive glucocorticoids enhances access of glucocorticosteroids to both the glucocorticoid and the mineralocorticoid receptors. In liver cirrhosis, enhanced mineralocorticoid and glucocorticoid effects are observed. We therefore investigated the impact of liver cirrhosis after bile duct ligation on the transcription and activity of 11 beta-OHSD1 and 11 beta-OHSD2 in the corresponding tissues. METHODS: Messenger RNA from 11 beta-OHSD1 and 11 beta-OHSD2 was assessed by reverse-transcription polymerase chain reaction; activity was assessed by measuring the interconversion of corticosterone to dehydrocorticosterone. The effect of bile and bile salts was determined using COS-1 cells transfected with 11 beta-OHSD1 or 11 beta-OHSD2. RESULTS: In liver tissue, the messenger RNA ratios of 11 beta-OHSD1 to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) levels and, in kidney tissue, the ratios of 11 beta-OHSD2 to GAPDH levels decreased after induction of liver cirrhosis. The 11 beta-OHSD activities were correspondingly reduced. Bile and individual bile salts inhibited 11 beta-OHSD1 and 11 beta-OHSD2 oxidative activity in transfected COS-1 cells. CONCLUSIONS: These findings indicate that in liver cirrhosis the mineralocorticoid and glucocorticoid receptor-protecting effects by the 11 beta-OHSD isoenzymes are down-regulated and that by the same mechanism the glucocorticoid and mineralocorticoid effects are enhanced.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1998

Coadministration of theophylline enhances diuretic response to furosemide in infants during extracorporeal membrane oxygenation: a randomized controlled pilot study.

OBJECTIVE: This pilot study evaluates the efficacy of low-dose theophylline administered before furosemide to enhance diuresis in neonates recovering from fluid retention during extracorporeal membrane oxygenation (ECMO). STUDY DESIGN: Infants receiving ECMO (n = 24) were randomized (double blind, placebo-controlled) to receive either regimen A (placebo/furosemide day 1, theophylline/furosemide day 2, placebo/furosemide day 3) or regimen B (theophylline/furosemide day 1, placebo/furosemide day 2, theophylline/furosemide day 3). Urine flows and renal functions were compared. RESULTS: Urine flow rate before initiation of diuretic therapy was not significantly different between groups A and B (2.6 +/- 1.4 vs 3.5 +/- 1.3 ml/kg/hr, respectively, p = 0.12). Infants who received theophylline/furosemide had significantly higher urine flow rates than those who received placebo/furosemide on day 1 (11.8 +/- 4.6 vs 7.2 +/- 2.4 ml/kg/hr, p < 0.01). The 24-hour fluid volumes and balances became significantly more negative with theophylline enhancement of furosemide's effect. There were no significant differences in renal function between the two groups. CONCLUSION: Low doses of theophylline given before furosemide administration significantly enhance diuretic response in infants with fluid retention during ECMO.

Diuresis↗

PubMed1998

Reduced 11beta-hydroxysteroid dehydrogenase activity in the remaining kidney following nephrectomy.

Intracellular access of steroids to gluco- and mineralocorticoid receptors is regulated by reduced 11beta-hydroxysteroid dehydrogenase (OHSD) 1 and 2. These enzymes convert active 11beta-OH-steroids into inactive 11-keto-steroids. The purpose of the present study was to establish whether the 11beta-OHSD1 and 11beta-OHSD2 are modulated in the remnant kidney 24 h or 14 days after uninephrectomy (UNX) in rats. Overall, 11beta-OHSD activity was analyzed by measuring the ratio of the exogenous 11beta-OH-steroid prednisolone to its 11-keto metabolite prednisone in vivo in kidney tissue using high performance liquid chromatography. To determine which isoenzyme accounts for the changed activity 24 h after UNX, the oxidation and reduction attributable to 11beta-OHSD1 and oxidation to 11beta-OHSD2 were analyzed in total renal extracts and in isolated glomeruli, proximal convoluted tubules (PCT), cortical ascending limbs, and cortical convoluted tubules (CCT). The messenger RNA content of 11beta-OHSD1 and 11beta-OHSD2 was measured by RT-PCR in renal tissues and single segments, using glyceraldehyde-3-phosphate-dehydrogenase as an internal standard. Protein amounts of 11beta-OHSD1 and 11beta-OHSD2 were assessed by Western blot. The prednisolone/prednisone ratio increased 24 h after UNX in 9 out of 10 animals (P < or = 0.0011), and was unchanged 14 days after UNX. 11Beta-OHSD1 oxidation (P < or = 0.032) and reduction activity (P < or = 0.002) declined 24 h after UNX in total extracts. 11Beta-OHSD1 oxidase activity was more than 3 times higher in PCT than in glomeruli, cortical ascending limbs, and CCT, and declined by 50% after UNX (P < or = 0.001). The reductase activity did not change following UNX in PCT. 11Beta-OHSD2 activity was 5-15 times higher in CCT than in the other segments, and decreased significantly after UNX (P < or = 0.008). UNX did not affect messenger RNA and protein levels of both enzymes in total renal extracts. In conclusion, 11beta-OHSD1 and 11beta-OHSD2 are predominantly expressed in PCT and CCT, respectively, and their corresponding oxidative activities decline after UNX. Thus, the access of 11beta-glucocorticosteroids to gluco- and mineralocorticoid receptors in the remaining kidney is facilitated after UNX.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1998

Furosemide inhibits 11beta-hydroxysteroid dehydrogenase type 2.

11Beta-hydroxsteroid dehydrogenase 2 (11beta-OHSD2) protects the nonselective renal mineralocorticoid receptor from the endogenous glucocorticoid cortisol. Thus, drugs inhibiting 11beta-OHSD2 might enhance urinary loss of potassium. As diuretics influence the renal handling of potassium, we analyzed the impact of 13 commonly used diuretics on 11beta-OHSD2. Furosemide was the only inhibitor. Its inhibition constant (Ki) was 30 micromol when extracts from COS-1 cells transfected with human 11beta-OHSD2 were used as an enzyme source. The type of inhibition was competitive. To establish whether furosemide inhibits 11beta-OHSD2 and 11beta-OHSD1 in the renal target tissue, isolated tubular segments from rats were analyzed. Furosemide decreased the oxidative activity of 11beta-OHSD2 in intact distal tubules and 11beta-OHSD1 in proximal convoluted tubules. For the assessment of furosemide on the excretion of corticosterone metabolites in vivo, rats were given furosemide i.p., and the ratio of tetrahydrocorticosterone plus 5alpha-tetrahydrocorticosterone to 11-dehydrotetrahydrocorticosterone was determined in urine. This ratio increased after the administration of furosemide in all animals, indicating inhibition of the oxidative activity of 11beta-OHSD. Thus, furosemide inhibits the 11beta-OHSD2 enzyme in the target tissue and might by that mechanism enhance the mineralocorticoid effect of 11beta-hydroxyglucocorticoids.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1998

A new polymorphic restriction site in the human 11 beta-hydroxysteroid dehydrogenase type 2 gene.

The 11 beta-hydroxysteroid dehydrogenase type II enzyme (11 beta HSD2) inactivates glucocorticoids in the kidney and thus prevents glucocorticoids from occupying the non-selective mineralocorticoid receptor in epithelial tissues. Mutations in the HSD11B2 gene have been found to cause the syndrome of apparent mineralocorticoid excess, a rare autosomal recessive disease characterized by severe hypertension. Thus, this locus could also be an ideal candidate involved in the etiology of primary hypertension. We identified a polymorphism in exon 3 characterized by a GAG to GAA transition at codon 178, with the loss of an Alu I restriction site and analysed it in an association study using end-stage renal disease patients, diabetic or essential hypertensive patients and control subjects. Two-hundred and eighty nine subjects and patients were analysed; the genotype was determined by amplification of genomic DNA and subsequent digestion with Alu I restriction enzyme. The prevalence of the Alu I allele was 8.6% in healthy control subjects (n = 116). This prevalence was lower (chi 2 P = 0.035 vs. controls) than the 18.0% in a group of renal transplant patients (n = 61). The corresponding values for patients with diabetes mellitus (n = 25), hypertension (n = 41) and patients on dialysis (n = 46) were 4.0%, 4.8% and 4.3%, respectively. There was no correlation between blood pressure and the marker in non-ESRD subjects. These data indicate the presence of a polymorphic marker in exon 3 of the HSD11B2 gene; this marker is associated with end-stage renal disease but not with essential hypertension in humans.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1997

Cortisol increases transfection efficiency of cells.

DNA uptake can be facilitated by addition of physiological amounts of 11beta-hydroxy glucocorticosteroids (such as cortisol) during transfection. In the presence of cortisol, but not of the inactive 11-keto glucocorticoid cortisone, twice as many cells uptake and express the reporter gene. The effect is specific and dose-dependent; the amounts of glucocorticosteroids needed to enhance transfection efficiency are in the nanomolar range, which corresponds to the dissociation constant of glucocorticoids for the glucocorticoid receptor in vitro. This effect can be abolished by an excess of the glucocorticoid antagonist RU486. We infer that the activated cytoplasmic glucocorticoid receptors enhance nuclear translocation of the incoming transfected DNA.

Animals↗

PubMed1997

Tumor necrosis factor alpha and interleukin 1beta enhance the cortisone/cortisol shuttle.

Endogenously released or exogenously administered glucocorticosteroids are relevant hormones for controlling inflammation. Only 11beta-hydroxy glucocorticosteroids, but not 11-keto glucocorticosteroids, activate glucocorticoid receptors. Since we found that glomerular mesangial cells (GMC) express 11beta-hydroxysteroid dehydrogenase 1 (11beta-OHSD1), which interconverts 11-keto glucocorticosteroids into 11beta-hydroxy glucocorticosteroids (cortisone/cortisol shuttle), we explored whether 11beta-OHSD1 determines the antiinflammatory effect of glucocorticosteroids. GMC exposed to interleukin (IL)-1beta or tumor necrosis factor alpha (TNF-alpha) release group II phospholipase A2 (PLA2), a key enzyme producing inflammatory mediators. 11beta-hydroxy glucocorticosteroids inhibited cytokine-induced transcription and release of PLA2 through a glucocorticoid receptor-dependent mechanism. This inhibition was enhanced by inhibiting 11beta-OHSD1. Interestingly, 11-keto glucocorticosteroids decreased cytokine-induced PLA2 release as well, a finding abrogated by inhibiting 11beta-OHSD1. Stimulating GMC with IL-1beta or TNF-alpha increased expression and reductase activity of 11beta-OHSD1. Similarly, this IL-1beta- and TNF-alpha-induced formation of active 11beta-hydroxy glucocorticosteroids from inert 11-keto glucocorticosteroids by the 11beta-OHSD1 was shown in the Kiki cell line that expresses the stably transfected bacterial beta-galactosidase gene under the control of a glucocorticosteroids response element. Thus, we conclude that 11beta-OHSD1 controls access of 11beta-hydroxy glucocorticosteroids and 11-keto glucocorticosteroids to glucocorticoid receptors and thus determines the anti-inflammatory effect of glucocorticosteroids. IL-1beta and TNF-alpha upregulate specifically the reductase activity of 11beta-OHSD1 and counterbalance by that mechanism their own proinflammatory effect.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1997

Augmentation of blood platelet levels by intratracheal administration of an adenovirus vector encoding human thrombopoietin cDNA.

This study was designed to evaluate the hypothesis that administration of a replication-deficient, recombinant adenovirus vector to the epithelial surface of the respiratory tract can be used to deliver a recombinant protein to the systemic circulation in sufficient quantities to evoke a systemic response appropriate to the recombinant protein. We administered AdCMV.TPO-an adenovirus vector containing an expression cassette coding for the human thrombopoietin (TPO) cDNA-to the respiratory epithelium of immunocompetent Balb/c mice. Over the following week, serum human TPO levels were elevated, platelet levels increased more than sixfold, and megakaryocytosis was evident in bone marrow. This strategy may be a useful approach to the nonparenteral administration of a variety of therapeutic recombinant proteins, such as those relevant to clotting, endocrine function, and bone-marrow function.

Adenoviridae↗

PubMed1997

Intermittent exposure to doxorubicin in vitro selects for multifactorial non-P-glycoprotein-associated multidrug resistance in RPMI 8226 human myeloma cells.

The purpose of the present study was to evaluate whether intermittent exposure to a constant dose of doxorubicin selects for multidrug resistance (MDR) in RPMI 8226 human myeloma cells and, if so, to determine the molecular mechanism. In an attempt to approximate clinical doxorubicin treatment in vitro, cells were exposed to a fixed dose of doxorubicin for 4 d alternating with growth in drug-free medium for 17 d. An MDR subline emerged, termed 8226/DOXint5, which was 3-4-fold resistant to doxorubicin, etoposide and m-AMSA, and 1.6-fold resistant to vincristine. Sensitivity to docetaxel, melphalan and cisplatin was normal. Verapamil normalized vincristine sensitivity but had little effect on resistance to the other agents. Cellular uptake and retention of daunorubicin and vincristine were reduced by approximately 10%. The 8226/DOXint5 cells showed diminished DNA topoisomerase IIalpha expression and increased expression of the multidrug resistance protein MRP. Expression of MDR1/P-glycoprotein was not detected. Immunostaining showed 70% of the cells to over-express the lung-resistance protein LRP. This new MDR myeloma cell line may prove to be a useful model for the development of strategies to overcome low-level, multifactorial MDR, which might be a common phenomenon in clinical myeloma treated with doxorubicin.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1997

Urinary 6 beta-hydroxycortisol excretion in rheumatoid arthritis.

The objective was to analyse whether the activity of the cytochrome P450 isoenzyme CYP3A4 is altered by disease activity of rheumatoid arthritis (RA). Urinary 6 beta-hydroxycortisol excretion, expressed as a fraction of the urinary creatinine output, was measured in 21 patients with RA treated with three different disease-modifying anti-rheumatic drugs (DMARDs) over 24 weeks. There were no correlations between urinary 6 beta-hydroxycortisol/creatinine (6 beta-OHC/Creat) ratio and measurements of disease activity such as plasma viscosity, Ritchie articular index and early morning stiffness. In addition, the three DMARDs sulphasalazine, sodium aurothiomalate and D-penicillamine, smoking and the intake of various CYP3A4 substrates had no consistent detectable effect on the 6 beta-OHC/Creat ratio. There is no evidence that the dosage of drugs metabolized by the CYP3A4 isoenzyme needs to be adjusted for disease activity in RA.

Adult↗

PubMed1997

Effects of insulin-like growth factor I combined with growth hormone on glucocorticoid-induced whole-body protein catabolism in man.

Treatment with insulin-like growth factor I (IGF-I) alone failed to affect glucocorticoid-induced protein catabolism in a previous study from our laboratory. To assess the effects of the combination of IGF-I and GH in a similar protocol, 24 normal subjects received (in a double-blind, randomized, placebo-controlled manner) s.c. injections of either GH alone (0.3 IU/kg.day), the combination of IGF-I (80 micrograms/kg.day) and GH (0.3 IU/kg.day), or placebo for a period of 6 days during which they were treated with methylprednisolone (0.5 mg/kg.day). Whole-body protein kinetics measured, using the [1-13C]-leucine infusion technique, demonstrated that leucine flux (a parameter of protein breakdown) increased during administration of glucocorticoids alone (placebo group) and during GH-treatment, whereas the glucocorticoid-induced increase was abolished during IGF-I plus GH (P < 0.03 vs. GH). Leucine oxidation (a parameter of irreversible protein catabolism) increased in the placebo group (+60 +/- 14.5%, P < 0.005, day 7 vs. day 1), remained unchanged in the GH group (+2.5 +/- 10%), and decreased in the combination group (-17.7 +/- 3.3%, P < 0.002, day 7 vs. day 1). Glucose MCR decreased in the group receiving placebo (P < 0.05) and remained unchanged during combined treatment with IGF-I plus GH. It is concluded that glucocorticoid-induced protein, catabolism (leucine oxidation) is abolished during coadministration of GH (anticatabolic effect), whereas treatment with IGF-I and GH results in a net anabolic effect without adverse effects on peripheral glucose clearance.

Adult↗

PubMed1997

Regulation of hematopoiesis by microvascular endothelium.

The bone marrow microenvironment is a complex three dimensional structure where hematopoietic stem cells proliferate, mature, migrate into the sinusoidal space, and enter the circulation in an exquisitely regulated fashion. Stromal cells within the BM microenvironment provide a suitable environment for self-renewal, proliferation and differentiation of hematopoietic stem cells. Within the hematopoietic microenvironment, whether it is embryonic yolk sac, fetal liver, or adult bone marrow, microvascular endothelium not only acts as a gatekeeper controlling the trafficking and homing of hematopoietic progenitors, but also provides cellular contact and secretes cytokines that allows for the preservation of the steady state hematopoiesis. Recently, homogenous monolayers of bone marrow endothelial cells (BMEC) have been isolated and cultivated in tissue culture. Long-term coculture studies have shown that BMEC monolayers are unique type of endothelium and can support long-term proliferation of hematopoietic progenitor cells particularly megakaryocytic and myeloid progenitor cells by constitutive elaboration of lineage-specific cytokines such as G-CSF, GM-CSF, M-CSF, Kit-ligand, IL6, FLK-2 ligand, and leukemia inhibitory factor. Direct cellular contact between hematopoietic progenitor cells and BMEC monolayers through specific adhesion molecules including beta1, beta2 integrins and selectins play a critical role in trafficking and possibly proliferation of hematopoietic stem cells. Dysfunction of microvascular endothelial cells within the hematopoietic microenvironment may result in stem cell disorders and progression to aplastic anemias, and contribute to graft failure during bone marrow transplantation. Further studies on the role of microvascular endothelium in the regulation of hematopoietic stem cell homing and proliferation may enhance our understanding of the pathophysiology of stem cell and leukemic disorders.

Antigens, CD34↗

PubMed1996

Interaction of plant lipids with 14 kDa phospholipase A2 enzymes.

Several structurally related plant lipids were isolated and their effect was assessed on the enzyme activity of group I (pancreatic and Naja mocambique venom) and group II (Crotalus atrox venom) phospholipase A2 (PLA2) enzymes, with labelled Escherichia coli as an enzyme substrate. The neutral monogalactosyldiacylglycerol (MGDG) and negatively charged diacylglyceryl alpha-D-glucuronide (DGGA) did not influence the enzyme activity of either group. Digalactosyldiacylglycerol (DGDG), another uncharged glycolipid, inhibited PLA2 activity in a dose-dependent manner to 60-70% of the control. Sulphoquinovosyldiacylglycerol (SQDG), which is also anionic, activated both groups of PLA2 enzyme. A similar activation was observed with the zwitterionic diacylglyceryl-O-(N,N,N-trimethylhomoserine) (DGTS) and diacylglyceryl-O-(hydroxymethyl)(N,N, N-trimethyl)-beta-alanine (DGTA). DGDG, SQDG and DGTS are dispersed homogeneously with low critical micelle concentrations (CMCs). The hydrodynamic radius of neutral DGDG is an order of magnitude larger than the charged lipids SQDG and DGTS. The inhibition of pig pancreatic PLA2 by DGDG was dependent on substrate concentration. The intrinsic fluorescence spectra of the enzyme was not changed in the presence of native or hydrogenated DGDG. Thus the inhibition is most probably due to a non-specific interaction of plant lipids with the substrate. Different lengths and saturations of the fatty acyl chains of DGDG did not alter the inhibition of PLA2, whereas deacylation abrogated the inhibitory effect. Both SQDG and DGTS activated pig pancreatic PLA2 in a dose-dependent manner. Saturation of the double bonds of these lipids decreased the activating effect. The fluorescence of pig pancreatic PLA2 incubated with SQDG and DGTS was enhanced by 2-fold and 3-fold respectively, suggesting the formation of a complex between enzyme and lipids. In conclusion, the effect of different plant lipids on PLA2 activity depends on different structural elements of the polar head group and their charge as well as the degree of unsaturation of the fatty acyl chains.

Animals↗

PubMed1996

Liver cirrhosis induces renal and liver phospholipase A2 activity in rats.

Maintenance of renal function in liver cirrhosis requires increased synthesis of arachidonic acid derived prostaglandin metabolites. Arachidonate metabolites have been reported to be involved in modulation of liver damage. The purpose of the present study was to establish whether the first enzyme of the prostaglandin cascade synthesis, the phospholipase A2(PLA2) is altered in liver cirrhosis induced by bile duct excision. The mRNA of PLA2(group I and II) and annexin-I a presumptive inhibitor of PLA2 enzyme was measured by PCR using glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as an internal standard. The mean mRNA ratio of group II PLA2/GAPDH was increased in liver tissue by 126% (P < 0.001) and in kidney tissue by 263% (P < 0.006) following induction of liver cirrhosis. The increase in group II PLA2 mRNA in cirrhotic animals was reflected by an increase in PLA2 protein and enzyme activity in both liver and kidney tissues. Since the mRNA of group I PLA2 was not detectable and Group IV PLA2 activity measured in liver and kidney tissue samples was very low and not changed following induction of cirrhosis, it is likely that the major PLA2 activity measured in liver and kidney corresponds to group II PLA2 enzyme. The mean mRNA ratio of annexin-I/GAPDH was increased in liver tissue by 115% (P < 0.05) but unchanged in kidney tissue following induction of cirrhosis. The protein content of annexin-I and -V were not affected by bile duct excision in liver and kidney tissue indicating that upregulation of group II PLA2 activity was not due to downregulation of annexin-I or -V. Group II PLA2 activity of glomerular mesangial cells stimulated by interleukin-1 beta was enhanced by bile juice and various bile salts. In conclusion, activity of group II PLA2 is upregulated partly due to enhanced transcription and translation in cirrhosis and is furthermore augmented by elevated levels of bile salts.

Animals↗

PubMed1996

Differences in phospholipase A2 activity between males and females and Asian Indians and Caucasians.

There is epidemiological evidence that chronic inflammatory diseases occur more frequently in female than in male subjects and prevail differently in various ethnic populations. Phospholipase A2 (PLA2) (group II) plays a key role in many inflammatory reactions by releasing free arachidonic acid, which is a prerequisite for the production of proinflammatory lipid mediators. We therefore, measured PLA2 activity in plasma, serum, leucocytes and lymphocytes in 20 female and 20 male subjects, 10 of each group being of Asian Indian and of Caucasian origin respectively. When PLA2 activity was measured in crude plasma and serum no dependency from gender and ethnicity was observed. Following acid extraction and heating, PLA2 activity in plasma was higher in Caucasians (27.8 +/- 2.2 nmol L-1 mg-1 protein 60 min-1) than in Asian Indians (17.9 +/- 2.5 nmol L-1 mg-1 protein 60 min-1) (P < 0.005) and higher in females (28.5 +/- 2.6 nmol L-1 mg-1 protein 60 min-1) than in males (17.3 +/- 2.0 nmol L-1 mg-1 protein 60 min-1) (P < 0.001). Similar differences were observed when only Asian Indian or Caucasian females were compared with their corresponding males. Contrary to plasma, in which the specific activity of PLA2 increased following acid extraction and heating, the activity was completely abrogated in serum after extraction and heating. Lymphocytes exhibited lower activities of PLA2 than neutrophils in all four groups of subjects investigated. Females had a tendency towards higher PLA2 activity in both lymphocytes and neutrophils than males. In conclusion the present investigation revealed an ethnic and sex-dependent basal activity of PLA2, a key enzyme in the pathogenesis of chronic inflammatory diseases.

Adult↗

PubMed1996

Haemodialysis activates phospholipase A2 enzyme.

BACKGROUND: Clinical and experimental evidence suggest that haemodialysis (HD) procedure is an inflammatory process. For the production of proinflammatory lipid mediators in many inflammatory reactions, the release of arachidonic acid by phospholipase A2 (PLA2) enzyme is a prerequisite. Therefore, the purpose of the present investigation was to establish whether the activity of PLA2 increases during HD and whether the increase depends on the type of dialyser used. METHODS: We performed dialysis in eight chronic HD patients. Blood samples entering and leaving the dialyser were obtained before and at 15, 60, 120 and 180 min after the dialysis was started, on one occasion using a cuprophane and on another occasion a cellulose triacetate dialyser. PLA2 activity was assessed in crude plasma and in plasma extract. RESULTS: PLA2 activity in plasma extract exhibited similar biochemical properties to that of inflammatory human synovial fluid PLA2 enzyme which is of group II PLA2. PLA2 activity in crude plasma represents a type of PLA2 other than the synovial type. In HD patients, baseline PLA2 activities in a crude plasma and plasma extract were significantly increased when compared to normal subjects. An increase in PLA2 activity was observed in crude plasma with a peak appearing at 15 min when the patients were dialysed with cuprophane and cellulose triacetate membranes. This increase was observed in both arterial and venous blood samples and was more pronounced when the patients were dialysed with cuprophane than with cellulose triacetate membranes. When PLA2 was assessed in plasma extract, the activity increased only with cuprophane but not with cellulose triacetate membranes. CONCLUSION: PLA2 activity in plasma is increased in HD patients and increases during the dialysis procedure to a greater extent with a less biocompatible membrane. Continuous activation of PLA2 might be relevant for long-term deleterious consequences of HD.

Adult↗

PubMed1995

The prognostic significance of protein-energy malnutrition in geriatric patients.

Although it has been shown that protein-energy malnutrition is a predictor of adverse outcome in geriatric patients, it is unclear whether this is due to underlying disease or disability, or whether malnutrition is an independent outcome predictor. To clarify the predictive role of malnutrition, we analysed the 4.5-year mortality and living location follow-ups of 219 geriatric patients admitted to a geriatric assessment unit. Prevalence of anthropometric and serological malnutrition indicators were between 13.7% and 39.8% at hospital admission. In bivariate models, prealbumin, subnormal arm muscle area, and subnormal body weight were predictors of mortality and survival at home. On the other hand, albumin, transferrin, and triceps skin-fold thickness did not predict these outcomes. In multivariate models the hazard ratio (HR) of 4.5-year mortality remained significant with an HR of 1.8 (95% CI 1.3-2.6) for subnormal arm muscle area, and 1.6 (95% CI 1.0-2.6) for subnormal body weight. Prealbumin was the strongest serological outcome predictor (multivariate mortality HR 1.9, 95% CI, 1.3-2.8). In these models, subnormal cognitive function, impaired physical function, and creatinine clearance < 30 ml/min were also associated with increased mortality. Malnutrition did not predict hospital discharge location, but among patients discharged home, those with initial malnutrition had a decreased length of survival at home. Our findings indicate that certain protein-energy malnutrition indicators are independent risk factors predicting decreased length of overall survival and survival at home in geriatric patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗