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Biomedical subjects

A Adam

Publications and source records attributed to A Adam.

At least 73 records · Page 4Linked to original sources
PubMed1999

Increase in blood bradykinin concentration after eccentric weight-training exercise in men.

The purpose of this study was to verify the possible appearance in the blood of bradykinin (BK) and des-Arg(9)-bradykinin (des-Arg(9)-BK) after eccentric exercise in 13 male subjects. Eccentric exercise (5 x 10 leg presses at 120% maximal voluntary concentric contraction) resulted in muscle damage and inflammation, as suggested by the significant increase in serum creatine kinase activity (from 204 +/- 41 to 322 +/- 63 U/l 12 h postexercise) and by severe lasting pain, which also peaked at 12 h postexercise. Blood BK and des-Arg(9)-BK concentrations were measured by competitive enzyme immunoassays using highly specific polyclonal rabbit IgG. Des-Arg(9)-BK concentration was not modified (preexercise: 44 +/- 14 pmol/l; pooled postexercise: 47 +/- 4 pmol/l). In contrast, BK concentration significantly increased immediately after the exercise session (68 +/- 9 vs. 42 +/- 3 pmol/l preexercise) and returned to basal values at 12, 24, and 48 h (pooled value: 40 +/- 4 pmol/l). This observation suggests that the inflammatory process due to eccentric exercise-induced muscle damage could be mediated in part by BK.

Adult↗
PubMed1999

The radiologist's view of expandable metallic stents for malignant esophageal obstruction.

Interventional radiologists place esophageal stents with great accuracy and low complication rates. The results of radiologic placement are similar to endoscopic stent insertion. The advantages of radiologic stent insertion are the ability to traverse very small strictures that cannot be crossed endoscopically and the ability to visualize and treat small fistulae and perforations at the time of stenting.

Biocompatible Materials↗
PubMed1998

Age-associated modulation of apoptosis and activation in murine B lymphocytes.

We have investigated the influence of age on B-cell responsiveness. The present study showed that the B-cell mitogen, lipopolysaccharide (LPS), similarly stimulated the proliferation of purified B lymphocytes obtained from either young mice (3 months) or old mice (24 months). In contrast, expression of the differentiation marker, alkaline phosphatase (ALP), was about fourfold higher in young mice than in older mice upon stimulation with LPS or with dextran sulfate (DXS) and interleukin-5 (IL-5). The occurrence of apoptosis during aging was then studied: unexpectedly, spontaneous cell death was double in B lymphocytes from young mice compared to older animals. Stimulation with DXS with or without IL-5 rescued B lymphocytes from cell death in young mice but protection decreased with aging, and no longer occurred in 24-month-old mice B cells. Meanwhile, the protective activity conferred by IL-4 was maintained at similar levels throughout aging. However, B cells from old mice were more responsive to apoptosis induction with cycloheximide, dibutyryl cAMP and dexamethasone. Together, the present results indicate an age-associated alteration in apoptosis and activation of B lymphocytes which could contribute to the age-related decline of the immune response.

Aging↗
PubMed1998

Inhibition of caspase activity induces a switch from apoptosis to necrosis.

The role of caspases in B lymphocyte cell death was investigated by using two broad spectrum inhibitors of the caspase family, Z-Asp-cmk and Z-VAD-fmk. They totally prevented spontaneous and drug-induced apoptosis and inhibited the CPP32/caspase-3-like activity exhibited by apoptotic cells. However, the suppression of apoptosis was not associated with a long-term increase of cell survival, but conversely, with a switch from apoptotic death to the necrotic form. These results strongly suggest that apoptosis and necrosis share common initiation pathways, the final issue being determined by the presence of an active caspase.

Amino Acid Chloromethyl Ketones↗
PubMed1998

Effects of omega-3 fatty acids on renal function and electrolyte excretion in aged persons.

Prostaglandin (PG) E2 formation, especially relevant for renal function in the state of renal vascular disease, is inhibited by omega-3 fatty acids. On the other hand, omega-3 fatty acids are under evaluation in chronic inflammatory kidney diseases, because of their ability to modulate immunologic cell response. We evaluated the effect of 1.7 g/d eicosapentaenoic acid (EPA), given with cod liver oil for four weeks to elderly persons with atherosclerosis. Enrichment of EPA coincided with inhibition of PG biosynthesis, transiently plasma creatinine increased, while creatinine clearance and excretion of solutes with the urine decreased in our experimental subjects. At the end of the four week study no effect of omega-3 fatty acids on renal function was found. Further studies are warranted to evaluate the potential benefit of omega-3 fatty acids on renal function in elderly persons.

Aged↗
PubMed1998

Metabolism of bradykinin by the rat coronary vascular bed.

OBJECTIVE: To study the metabolism of bradykinin (BK) after a single passage through the coronary bed in isolated Langendorff rat hearts. METHODS: BK was infused into the aortic flow line to obtain a final concentration of 10 nM, and the coronary, effluent was collected to quantify BK and des-Arg9-BK by competitive enzyme immunoassay. The nature of immunoreactive material was confirmed by immunograms after HPLC separation. The experiments were performed with hearts perfused at either one of the following coronary flow rates: 1, 5 or 10 ml/min. RESULTS: BK recovery without inhibitors was 86.3 +/- 2.9, 60.8 +/- 6.3, and 29.6 +/- 6.8% at 10, 5, and 1 ml/min, respectively. The Vmax/Km ratios at these coronary flow rates were 2.19 +/- 0.72, 4.81 +/- 0.64, and 2.59 +/- 0.33 min-1 g-1), respectively. The angiotensin-converting enzyme (ACE) inhibitor, enalaprilat (130 nM), reduced BK degradation at all flow rates. Inhibition of neutral endopeptidase with retrothiorphan (25 nM) had no effect on BK degradation. However, the combined treatment with enalapril and retrothiorphan reduced BK degradation to lower values than enalaprilat alone. The effect of enzyme inhibitors on BK recovery was inversely related to coronary flow: inhibiting BK degradation markedly increased BK recovery at 1 ml/min, but had no effect at 10 ml/min. The kininase I metabolite of BK, des-Arg9-BK, could not be detected under these experimental conditions. CONCLUSIONS: ACE is the major enzyme responsible for BK degradation during a single passage through the coronary bed. Neutral endopeptidase contributes to BK degradation only when ACE activity is impaired. The effect of enzyme inhibitors on the coronary concentration of BK is highly dependent on coronary flow rate.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

Induction of apoptosis by dexamethasone in the B cell lineage.

The susceptibility to induction of apoptosis by the synthetic glucocorticoid, dexamethasone (Dex), was analysed at different stages of B cell maturation. Cells of the 70Z/3 pre-B cell line, expressing cytoplasmic mu chains, and LPS-stimulated 70Z/3 cells, expressing surface IgM, were used as a model of differentiation of pre-B cells into immature B cells. Cell proliferation and cell cycle progression were similarly inhibited by Dex (100 nM) in both naive 70Z/3 pre-B cells and in LPS-stimulated 70Z/3 cells. In contrast, Dex failed to affect apoptosis of naive 70Z/3 cells while it increased that of LPS-stimulated 70Z/3 cells. Splenic mature B lymphocytes were highly susceptible to Dex-induced apoptosis since subphysiological doses (5 nM) increased the frequency of apoptotic cells to more than 80%. On the other hand, the treatment of B lymphocytes with LPS, which led to proliferation and differentiation into immunoblasts, decreased the susceptibility to Dex-induced apoptosis. These effects were mediated by the glucocorticoid receptor since they were abrogated by the RU 486 antagonist. The response of B cells to glucocorticoids is thus dependent on their stage of differentiation.

Animals↗
PubMed1998

ACE insertion/deletion genotype affects bradykinin metabolism.

A deletion allele of the angiotensin-converting enzyme (ACE) gene has been associated with increased serum ACE activity, enhanced conversion of angiotensin (Ang) I to Ang II, and cardiovascular morbidity. This study tested the hypothesis that the ACE deletion allele is also associated with enhanced degradation of bradykinin, a vasoprotective peptide. Metabolism of synthetic bradykinin was measured in sera obtained from subjects who were homozygous for either the ACE deletion (n=12) or insertion (n=8) allele and who had participated in an Ang I-infusion protocol. ACE levels tended to be increased in subjects who were DD compared with those who were II [41.2 (95% CI, 27.9, 54.3) vs. 28.0 IU/L (20.0, 35.9); t=-1.6; p=0.1 18]. During Ang I infusion, plasma Ang II concentrations were increased in DD compared with II subjects (F =4.4; p=0.052). In contrast, the half-life of bradykinin was significantly decreased in sera obtained from ACE DD compared with II subjects [26.3 s (17.8, 34.6 s) vs. 42.1 s (24.4, 59.9 s); t=-2.4; p=0.029]. Moreover, there were significant inverse relations between the half-life of bradykinin and serum ACE activity (p < 0.001) and between the half-life of bradykinin and the conversion of Ang I to Ang II (p=0.026). This study confirms that ACE genotype determines bradykinin degradation and suggests another mechanism whereby the ACE D allele could be associated with deleterious cardiovascular effects.

Adult↗
PubMed1998

Hand dominance and motor unit firing behavior.

Daily preferential use was shown to alter physiological and mechanical properties of skeletal muscle. This study was aimed at revealing differences in the control strategy of muscle pairs in humans who show a clear preference for one hand. We compared the motor unit (MU) recruitment and firing behavior in the first dorsal interosseous (FDI) muscle of both hands in eight male volunteers whose hand preference was evaluated with the use of a standard questionnaire. Myoelectric signals were recorded while subjects isometrically abducted the index finger at 30% of the maximal voluntary contraction (MVC) force. A myoelectric signal decomposition technique was used to accurately identify MU firing times from the myoelectric signal. In MUs of the dominant hand, mean values for recruitment threshold, initial firing rate, average firing rate at target force, and discharge variability were lower when compared with the nondominant hand. Analysis of the cross-correlation between mean firing rate and muscle force revealed cross-correlation peaks of longer latency in the dominant hand than in the nondominant side. This lag of the force output with respect to fluctuations in the firing behavior of MUs is indicative of a greater mechanical delay in the dominant FDI muscle. MVC force was not significantly different across muscle pairs, but the variability of force at the submaximal target level was higher in the nondominant side. The presence of lower average firing rates, lower recruitment thresholds, and greater firing rate/force delay in the dominant hand is consistent with the notion of an increased percentage of slow twitch fibers in the preferentially used muscle, allowing twitch fusion and force buildup to occur at lower firing rates. It is suggested that a lifetime of preferred use may cause adaptations in the fiber composition of the dominant muscle such that the mechanical effectiveness of its MUs increased.

Action Potentials↗
PubMed1998

A new design of the esophageal Wallstent endoprosthesis resistant to distal migration.

OBJECTIVE: Because plastic-covered metallic stents used in the palliation of patients with unresectable esophageal cancer are associated with significant rates of migration, particularly when the lower end of the stent projects into the gastric fundus, the purpose of this study was to establish whether two new prototype designs of the Wallstent esophageal endoprosthesis are prone to migration. SUBJECTS AND METHODS: A cylindrical stent and a conical stent were studied. Both designs included plastic covering inside the metallic mesh. In addition, the conical device incorporated a variation in the braiding angle between the upper and lower parts of the endoprosthesis. Ten conical stents and eight cylindrical stents were inserted in 18 patients with tumors involving the gastroesophageal junction who were followed up with esophagography and endoscopy. RESULTS: All insertions of stents were successful. Two cylindrical stents (25%) migrated distally. Two conical stents (20%) migrated proximally. One perforation occurred that was associated with distal migration of a cylindrical stent. CONCLUSION: The frequency of distal migration of cylindrical stents is unacceptably high. Conical stents are resistant to distal migration, although improvements in design are required to deal with the problem of proximal migration.

Adenocarcinoma↗
PubMed1998

Radiological management of oesophageal strictures.

Interventional radiologists have an increasing role in managing oesophageal strictures. Fluoroscopically-guided balloon dilatation can relieve dysphagia in patients with benign strictures in about 95% of cases with minimal associated complications. Over 95% of patients with inoperable malignant oesophageal strictures can be successfully palliated with self-expanding metallic stents.

Catheterization↗
PubMed1997

[Selenium concentration in erythrocytes of patients with rheumatoid arthritis. Clinical and laboratory chemistry infection markers during administration of selenium].

PATIENTS AND METHODS: Seventy patients with definitive rheumatoid arthritis were matched to built 2 groups, which were double-blind and randomized allocated to supplementation with sodium-selenit 200 micrograms/d or placebo for 3 months, each. Both groups were given fish oil fatty acids (30 mg/kg body weight), DMARDS were continued throughout the study, while variations in steroids or NSAD were admitted. RESULTS: Selenium concentrations in erythrocytes of patients with rheumatoid arthritis were 85.1 +/- 26 micrograms/l, and significantly lower than found in an average German population (123 +/- 23 micrograms/l). During the observation period of 3 months normal selenium concentrations were not restored, despite supplementation higher than RDA. At the end of the experimental period the selenium supplemented group showed less tender or swollen joints, and morning stiffness. Selen-supplemented patients needed less cortisone and NSAD than controls. In accordance with clinical improvement we found a decrease of laboratory indicators of inflammation (C-reactive protein, alpha 2-globuline, prostaglandin E2). CONCLUSION: No side effects of supplementation with selenium were noted, which can be considered as adjuvant therapy in patients with rheumatoid arthritis.

Adult↗
PubMed1997

A blood test for intestinal permeability and function: a new tool for the diagnosis of chronic intestinal disease in dogs.

We demonstrate that rhamnose, 3-O-methyl-D-glucose, D-xylose and lactulose may be quantified accurately in blood by HPLC and pulsed amperometric detection, thus enabling studies of intestinal permeability and function to be carried out using plasma samples. Prior to HPLC, the endogenous glucose was enzymatically modified to gluconic acid and the protein precipitated. The precision of the quantification of the sugars in plasma (CV: 2.2-5.7%; 8.7-10.6% at very low concentrations) compared well with the quantification in urine. The results for groups of 8 dogs with small intestinal bacterial overgrowth and 12 dogs with inflammatory bowel disease were shown to be significantly different from a group of 20 normal control dogs (P < 0.001), demonstrating the test's value as a diagnostic tool. The normal ranges in blood 2 h post oral administration were determined to be 0.05-0.17 for the lactulose/rhamnose ratio and 0.45-0.65 for the xylose/3-O-methylglucose ratio. This method may be employed advantageously when the collection of urine in intestinal permeability and function tests is difficult.

3-O-Methylglucose↗
PubMed1997

Zidovudine potentiates local and systemic inflammatory responses in the rat.

The effect of chronic treatment with zidovudine (AZT) on the inflammatory response was examined in the rat. AZT was administered orally for 36 days. On day 35, inflammation was induced by hindpaw injection of 1% carrageenan lambda. Paw edema over a 24-hour period was used as a marker of the local inflammatory reaction. On day 36, quantification of immunoreactive T-kininogen and alpha 1-inhibitor-3 in liver and serum was used to assess the systemic inflammatory response. Albumin was selected as a protein whose concentration is modified only slightly or not at all during the acute-phase response. Animals treated with AZT transiently exhibited significantly greater (18%) paw edema 3 hours after carrageenan injection. AZT treatment alone induced a 1.8-fold increase in serum T-kininogen concentration, but it had no effect on albumin and alpha 1-inhibitor-3. In rats with inflamed paws, AZT administration led to a significant increase in liver (3.4-fold) and serum (1.8-fold) immunoreactive T-kininogen content. Dot blot analysis of total RNA isolated from liver correlated with the protein measurements. Our results indicate that chronic treatment with AZT potentiates the nonspecific local and the systemic inflammatory responses in the rat.

Acute-Phase Proteins↗