Search PubMed⌕ Search

Biomedical subjects

J Klein

Publications and source records attributed to J Klein.

At least 271 records · Page 15Linked to original sources
PubMed1997

Reference values for the trace elements copper, manganese, selenium, and zinc in the serum/plasma of children, adolescents, and adults.

Up to now few plasma or serum reference or serum reference values have been available for the assessment of the essential trace element supply status in different age groups covering the whole range of life range. In the present investigation, the concentrations of copper, manganese, selenium, and zinc were determined in the serum of 137 healthy children and in the plasma of 68 blood-donors. The age distribution within these groups ranged from 1 month to 18 years and from 22 to 75 years. The determinations were carried out directly by means of electrothermal atomic absorption spectrophotometry with Zeeman background compensation. The adult plasma reference values (mean +/- 2 SD) were 1.65 +/- 8.6 mumol/1 for copper, 14.3 +/- 11.4 nmol/1 for manganese, 0.80 +/- 0.36 mumol/1 for selenium, and 16.6 +/- mumol/1 for zinc. No correlation between concentration of elements and sex could be established. In the child and adolescent group, the manganese levels exhibited an age-dependent linear decrease (54% of the starting value, slope 0.92, r = 0.4, p < 0.001), the copper and the selenium concentrations, respectively, exhibited an exponential increase (107%, r = 0.59 and 174%, r = 0.61), with the highest value in the age group of 6 to 10 years. Reference ranges are established for 9 different age groups. The results reflect the known physiological data on the trace element content in the tissue of children and their diet. The present study is an important pre-requisite for diagnosis and therapy of trace element deficiencies in all age groups.

Adolescent↗
PubMed1997

The differing prognostic utility of exercise radionuclide ventriculography in coronary artery disease patients with and without prior myocardial infarction.

UNLABELLED: Previous studies have documented the prognostic utility of left ventricular ejection fraction response to exercise primarily in populations without prior myocardial infarction. We undertook a study to assess the prognostic utility of exercise left ventricular ejection fraction and segmental wall motion response during exercise radionuclide ventriculography in coronary artery disease patients with and without prior myocardial infarction. METHODS: We examined the comparative prognostic utility of left ventricular ejection fraction and segmental wall motion response during upright bicycle exercise radionuclide ventriculography in 419 coronary artery disease patients with (n = 217) and without (n = 202) prior myocardial infarction using univariate and multivariate hierarchical regression analyses. RESULTS: During an average followup period of 61 months, 96 patients (23%) suffered cardiac events, including 55/217 (25%) of the patients with prior myocardial infarction and 41/200 (21%) of the patients without prior myocardial infarction (p = ns). Both cumulative Kaplan-Meier survival analyses and stepwise hierarchical Cox survival analyses demonstrated that peak left ventricular ejection fraction < 55% was a significant predictor of cardiac events in patients without prior myocardial infarction (p = 0.04), whereas an exercise wall motion worsening score > or = 2 was a significant predictor in patients with a prior myocardial infarction (p = 0.0001). CONCLUSIONS: The prognostic utility of exercise radionuclide ventriculography variables differ according to the presence or absence of prior myocardial infarction. Global function, assessed by peak left ventricular ejection fraction, adds the greatest prognostic information in patients without prior myocardial infarction, whereas regional function, assessed by exercise wall motion worsening, is the best predictor among patients with prior myocardial infarction.

Adult↗
PubMed1997

An improved limited sampling method for individualised busulphan dosing in bone marrow transplantation in children.

Busulphan (BU) pharmacokinetic (PK) studies in children undergoing bone marrow transplantation suggest that individual BU dosing may be necessary to optimise BU systemic exposure. Optimising BU systemic exposure may improve outcome and decrease toxicity in BMT. Because of practical limitations in obtaining blood from children and for financial reasons, a limited sampling method (LSM) is needed. However, such methods for BU have not been validated in children. In the present study, we individualized oral BU dosing in 10 children to target an area under the curve of BU (BU AUC) of 900-1400 microM/min based on BU AUC(0-infinity) calculated from nine serum BU concentrations performed after a BU test dose of 40 mg/m2. We validated a LSM using 3 BU concentrations to determine AUC. Six of nine patients studied (one patient non-evaluable), required their doses modified (3, lower; 3, higher). The mean percent dose change was 26.2% (range -33.3% to +45.3%). Our three sample LSM BU AUC(0-infinity) (1098 +/- 344, mean +/- 1 s.d.) correlated highly with our nine sample BU AUC(0-infinity) (1132 +/- 389, Pearson r = 0.98, P = 0.0001) and was not significantly different by t-test (P = 0.3). The mean percentage difference between the three sample LSM AUCs and the nine sample AUCs in each of our patients was 7.5%, (range -10.99% to +9.4%). Trough levels correlated extremely well with AUC (r = 0.95, P = 0.0001). Individual BU dosing, based on AUC, is necessary in most children to achieve targeted levels of BU therapy. An LSM of three BU concentrations performed at 0.5 h, 1 h and 6 h post-BU test dose closely predicts the AUC calculated from nine sampling points.

Alkylating Agents↗
PubMed1997

HLA-DRB9--possible remnant of an ancient functional DRB subregion.

The DRB subregion of the HLA complex contains, in addition to the functional genes, a number of pseudogenes and gene fragments. Fourteen kilobases of DNA were sequenced from the segment upstream of the DRB9 gene fragment, as well as shorter segments from different HLA and corresponding ape haplotypes. The analysis of the sequences and restriction fragments indicates that the segment is a remnant of an ancient DRB subregion which may have been functional before the primate radiation and which later became the source of extant functional DRB genes in various primate groups, different ones in different groups. The remnant segment has remained constant in its organization for at least 4 million years. This constancy contrasts with the variability of the adjacent functional part of the DRB subregion occupied by the DRB1 and other loci. The constancy may be related to the monomorphism and evolutionary conservation of the DRA locus.

Base Sequence↗
PubMed1997

Salivary measurement of deferiprone concentrations and correlation with serum levels.

Deferiprone (L1) is the first clinically available oral iron chelator and it has been proven to be effective for the treatment of transfusional iron overload in thalassemic patients. Because many of these patients have impaired compliance with their medications, effective means of continuous monitoring of compliance are crucial. Saliva drug monitoring has the potential advantage of an easy, noninvasive approach, assuming that it represents serum levels. However, drugs have variable correlations between saliva and serum concentration. We compared serum and saliva levels of L1 at various time points after ingestion of a 75 mg/kg/day dose in nine thalassemic patients. A highly significant correlation between serum-free L1 and saliva levels (r = 0.97, p = 0.0003) was found. Pharmacokinetic profiles were similar using serum and saliva monitoring. We conclude that saliva can be substituted for serum in monitoring L1 levels.

Deferiprone↗
PubMed1997

Correlation of morphine sulfate in blood plasma and saliva in pediatric patients.

This study sought to determine whether saliva concentrations of morphine correlate with plasma levels of morphine in pediatric patients receiving morphine analgesia for severe pain, and to evaluate whether the measurement of saliva morphine concentrations would be a useful, noninvasive, clinical tool to diagnose systemic exposure to morphine. Fifteen pediatric patients were enrolled; for the control group, 18 adult volunteers were recruited. Patients received continuous morphine drips to ameliorate pain caused by a sickle cell vasoocclusive crisis (range, 10-40 micrograms/kg.h). Control subjects were randomized into those receiving acetaminophen with either 8 mg (n = 13) or 30 mg (n = 5) of codeine. All participants fasted at least 2 hours before sample collection. Blood and saliva samples were collected simultaneously. All samples were analyzed by radioimmunoassay for morphine. There was no correlation between saliva and plasma morphine concentrations in either the patients receiving intravenous morphine (r = 0.04, P = 0.89) or in the controls receiving codeine (r = 0.43, P = 0.08). There was no observed difference in the mean counts per minute (CPM) for saliva samples in the pH range 3.96 to 8.06. Saliva concentrations of morphine cannot be used to predict the plasma concentration of morphine in children or adults. However, the concentration of morphine in saliva may be used as a qualitative indicator of systemic exposure to morphine in a subject.

Adolescent↗
PubMed1997

Reduction of azo dyes by redox mediators originating in the naphthalenesulfonic acid degradation pathway of Sphingomonas sp. strain BN6.

The anaerobic reduction of azo dyes by Sphingomonas sp. strain BN6 was analyzed. Aerobic conversion of 2-naphthalenesulfonate (2NS) by cells of strain BN6 stimulated the subsequent anaerobic reduction of the sulfonated azo dye amaranth at least 10-fold. In contrast, in crude extracts, the azo reductase activity was not stimulated. A mutant of strain BN6 which was not able to metabolize 2NS showed increased amaranth reduction rates only when the cells were resuspended in the culture supernatant of 2NS-grown BN6 wild-type cells. The same increase could be observed with different bacterial strains. This suggested the presence of an extracellular factor which was formed during the degradation of 2NS by strain BN6. The addition of 1,2-dihydroxynaphthalene, the first intermediate of the degradation pathway of 2NS, or its decomposition products to cell suspensions of the mutant of strain BN6 (2NS-) increased the activity of amaranth reduction. The presence of bacterial cells was needed to maintain the reduction process. Thus, the decomposition products of 1,2-dihydroxynaphthalene are suggested to act as redox mediators which are able to anaerobically shuttle reduction equivalents from the cells to the extracellular azo dye.

Amaranth Dye↗
PubMed1997

Localization of the Enzyme System Involved in Anaerobic Reduction of Azo Dyes by Sphingomonas sp. Strain BN6 and Effect of Artificial Redox Mediators on the Rate of Azo Dye Reduction.

The effect of different artificial redox mediators on the anaerobic reduction of azo dyes by Sphingomonas sp. strain BN6 or activated sludge was investigated. Reduction rates were greatly enhanced in the presence of sulfonated anthraquinones. For strain BN6, the presence of both cytoplasmic and membrane-bound azo reductase activities was shown.

Journal Article↗
PubMed1997

Clinical utilization of the neonatal hair test for cocaine: a four-year experience in Toronto.

BACKGROUND: There has been a steady increase in the number of newborns affected by maternal drug use. Cocaine and its metabolites cross the placenta and have been routinely measured in neonatal urine; however, due to the short half-life of the drug many exposed fetuses have negative urine tests. We have developed a neonatal hair test for measuring cocaine and its metabolites by radioimmunoassay. Since the validation of this test we prospectively evaluated its clinical utility by physicians, hospital nurseries and social welfare agencies who requested neonatal hair analysis to verify clinical suspicion of maternal cocaine use during pregnancy. OBJECTIVE: The objective of the present research was to establish the sensitivity of the hair test in validating clinical suspicion of in utero exposure to cocaine in the presence of negative urine test. HYPOTHESIS: We hypothesized that the use of the hair test in cases of clinical suspicion but negative urine test will yield a substantially higher rate of positivity than expected in the general population. DESIGN: Between October 1991 and April 1995 we prospectively analyzed a total of 192 neonatal hair samples to confirm clinical suspicions of intrauterine exposure to cocaine. Of these, 10 did not have sufficient hair to analyze for cocaine metabolites. RESULTS AND DISCUSSION: Fifty-five (30%) of the remaining 182 were positive for cocaine metabolite. This rate was 5.5-fold higher than the 5.5% found by us in a population-based research study in three nurseries in Toronto (p < 0.001), thus documenting the efficiency of this test in confirming clinical suspicions of fetal exposure to cocaine. Benzoylecgonine concentrations in this cohort were 2-fold higher than among positive cases in a previous population-based screening study (p = 0.0001) indicating that when clinical suspicions prompted physicians to test neonatal hair, they identify a subgroup of heavy cocaine users, who are probably at higher perinatal risks.

Cocaine↗
PubMed1997

[The role of the portosystemic shunt in modern treatment of portal hypertension].

The authors discuss the importance of portosystemic anastomoses in contemporary treatment of portal hypertension, in particular in relation to TIPS. As a basis they use their own experience with 28 portosystemic anastomoses during the last five years and conclude that a correctly indicated anastomosis has certain advantages over TIPS. The basic requirements for indication of surgical peripheral portosystemic anastomoses are: 1. stage Child A (or onset of B), 2. posthaemorrhagic conditions, 3. satisfactory general condition, 4. stabilized liver disease and planned surgery.

Humans↗
PubMed1997

Acetylcholine release and choline availability in rat hippocampus: effects of exogenous choline and nicotinamide.

The influence of choline availability on acetylcholine (ACh) release in the hippocampus of the awake rat was investigated using the microdialysis procedure. Three treatments enhancing choline availability for basal and atropine-evoked ACh release were evaluated: acute administration of choline chloride (20 mg/kg i.p.); pretreatment of animals with nicotinamide (10 mmol/kg s.c.) 2 hr before atropine injection and dietary choline supplementation (5-fold increase of choline intake for 15-18 days). Although acute choline administration led to a short-lasting (15 min) increase of basal choline efflux by 25% and nicotinamide caused a long-lasting (5 hr) increase by 105%, neither one affected basal ACh release. However, basal release of choline (1.38 pmol/min) and of ACh (114 fmol/min) in the hippocampus was slightly increased in choline-supplemented animals (choline: 1.92 pmol/min; ACh: 140 fmol/min). In untreated animals, atropine administration caused a 3-fold increase of ACh efflux that lasted approximately 2.5 hr. All treatments, acute or chronic choline and nicotinamide, led to significant increases of the maximum and duration of atropine-evoked ACh release. Total atropine-evoked ACh efflux (area under the curve) was increased 2- to 3-fold, with the largest effect evoked by the combination of nicotinamide and choline. The results clearly demonstrate that, under stimulated conditions, hippocampal ACh release could be facilitated when the availability of choline for ACh synthesis was enhanced by dietary or pharmacological means. Under certain conditions, significant effects of increased choline availability on ACh release can be revealed in the absence of an overall increase of extracellular choline.

Acetylcholine↗
PubMed1997

[Peritoneovenous shunt in the surgical treatment of ascites in patients with liver cirrhosis].

The authors present their experience with the surgical treatment of ascites in patients with cirrhosis of the liver by means of a peritoneovenous shunt (PVS). In 1991-1996 they established 25 PVS in 23 patients. The survival of patients, conditioned by the state of the parenchyma and haemorrhagic complications due to portal hypertension was not significantly affected by the shunt. In all patients regression of the tension ascites was recorded with improvement of the quality of life, improvement of the milieu interior and nutritional status.

Adult↗
PubMed1997

[Disconnection as the last possible therapy of hemorrhage in esophageal varices].

The authors draw attention to their favourable results of disconnection in haemorrhage of oesophageal varices. This favourable result applies to immediate results as well as long-term results. They emphasize in particular the fact that disconnection can be used also when other methods are not feasible for various reasons. This fact is demonstrated by the authors on three patients whose complicated history and general condition were such that disconnection was the only solution of the situation.

Adult↗