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Biomedical subjects

M Heck

Publications and source records attributed to M Heck.

At least 37 records · Page 2Linked to original sources
PubMed1999

Effect of long-term trimethoprim-sulfamethoxazole prophylaxis on ascites formation, bacterial translocation, spontaneous bacterial peritonitis, and survival in cirrhotic rats.

Selective intestinal decontamination with norfloxacin is useful in preventing spontaneous bacterial peritonitis in cirrhotic patients and also in cirrhotic rats. The emergence of norfloxacin-resistant infections in these patients warrants a search for alternative therapies. The aim of this study was to evaluate the effect of long-term trimethoprim-sulfamethoxazole administration on carbon tetrachloride (CCl4) -induced cirrhosis in rats with specific attention to intestinal flora, bacterial translocation, spontaneous bacterial peritonitis (SBP), and survival. Male Sprague-Dawley rats received CCl4 administered weekly by gavage. After eight weeks of CCl4 administration rats were randomly allocated into two groups. Group I received daily overnight trimethoprim-sulfamethoxazole diluted in phenobarbital water during follow-up and group II did not. The rats were killed when gravely ill, and a laparotomy was performed to culture samples of cecal stool, mesenteric lymph nodes, and portal and inferior vena caval blood. There was a trend toward a reduction in the incidence of bacterial translocation (8/17 vs 11/14, respectively) and SBP (5/17 vs 7/14, respectively) in treated rats that were killed just before death compared to untreated rats. A decrease in the incidence of bacterial translocation caused by gram-negative bacilli was observed in group I (17.6% vs 78.6%, P < 0.01). The development of ascites was delayed in group I (P < 0.05) and survival was prolonged in group I (P < 0.05), despite a higher CCl4 dose in this group (P < 0.05). In conclusion, long-term prophylactic trimethoprim-sulfamethoxazole administration in CCl4-induced cirrhosis in rats delayed the development of ascites, prolonged survival, and reduced the incidence of gram-negative bacterial translocation but not of SBP, without increasing gram-positive episodes. These data suggest that trimethoprim-sulfamethoxazole might be a good alternative to norfloxacin for preventing gram-negative bacterial translocation.

Animals↗
PubMed1999

Validation of binary typing for Staphylococcus aureus strains.

Most of the DNA-based methods for genetic typing of Staphylococcus aureus strains generate complex banding patterns. Therefore, we have developed a binary typing procedure involving strain-differentiating DNA probes which were generated on the basis of randomly amplified polymorphic DNA (RAPD) analysis. We present and validate the usefulness of 15 DNA probes, according to generally accepted performance criteria for molecular typing systems. RAPD analysis with multiple primers was performed on 376 S. aureus strains of which 97% were methicillin resistant (MRSA). Among the 1,128 RAPD patterns generated, 66 were selected which identified 124 unique DNA fragments. From these amplicons, only 12% turned out to be useful for isolate-specific binary typing. The nature of the RAPD-generated DNA fragments was investigated by partial DNA sequence analysis. Several homologies with known S. aureus sequences and with genes from other species were discovered; however, 87% of the probe sequences are of previously unknown origin. The locations of most of the DNA probes on the chromosome of S. aureus NCTC 8325 were determined by hybridization. Seven fragments were randomly dispersed along the genome, five were clustered within the 2500- to 2600-kb position of the genome, and the remaining four did not recognize complementary sequences in S. aureus NCTC 8325. A total of 103 S. aureus strains (69% MRSA) were used for the validation of the binary typing technique. The 15 DNA probes provided stable epidemiological markers, both in vitro (type consistency after serial passages on culture media) and in vivo (comparison of sequential isolates recovered from cases of persistent colonization). The discriminatory power of binary typing (D = 0.998) exceeded that of pulsed-field gel electrophoresis (D = 0.966) and RAPD analysis (D = 0.949). Reproducibility, measured by analyzing multiple strains belonging to a multitude of different epidemiological clusters, was comparable to that of other genotyping techniques used. Contribution of the DNA probes to the discriminatory power of the system was analyzed by comparison of dendrograms. This study demonstrates that binary typing is a robust tool for the genetic typing of S. aureus isolates.

Base Sequence↗
PubMed1999

Rapid slide latex agglutination test for detection of methicillin resistance in Staphylococcus aureus.

The MRSA screen test (Denka Seiken Co., Ltd.), a commercially available, rapid (20-min) slide latex agglutination test for the determination of methicillin resistance by detection of PBP 2a in Staphylococcus aureus, was compared with the oxacillin agar screen test and PCR detection of the mecA gene. A total of 563 S. aureus isolates were tested. Two hundred ninety-six of the isolates were methicillin-susceptible isolates from cultures of blood from consecutive patients. Also, 267 methicillin-resistant isolates that comprised 248 different phage types were tested. Methicillin resistance was defined as the presence of the mecA gene. Of the 267 mecA gene-positive isolates, 263 were positive by the MRSA screen test (sensitivity, 98.5%), and all the mecA-gene negative strains were negative by the MRSA screen test (specificity, 100%). The oxacillin agar screen test detected methicillin resistance in 250 of the mecA gene-positive isolates (sensitivity, 93.6%). The sensitivity of the MRSA screen test was statistically significantly higher than the sensitivity of the oxacillin agar screen test (P < 0. 05). The MRSA screen test is a highly sensitive and specific test for the detection of methicillin resistance. Also, it offers results within half an hour and is easy to perform, which makes this test a valuable tool in the ongoing battle against methicillin-resistant S. aureus.

Latex Fixation Tests↗
PubMed1999

Specific progesterone binding to a membrane protein and related nongenomic effects on Ca2+-fluxes in sperm.

Rapid, nongenomic effects of steroids are supposed to be transmitted by membrane receptors unrelated to the classic intracellular steroid receptors. In this context, a putative progesterone membrane binding protein (mPR) has been identified, recently. Here we show that expression of mPR-cDNA in CHO cells leads to increased microsomal progesterone binding. This result is mirrored by effects of an antibody raised against the recombinant E. coli mPR which suppressed the rapid progesterone-initiated Ca2+ increase in sperm. Our results support the assumption that mPR represents the first steroid membrane receptor or a part of it involved in rapid, nongenomic steroid signalling.

Animals↗
PubMed1998

Characterization of a 190-kilobase pair domain of human type I hair keratin genes.

Polymerase chain reaction-based screening of an arrayed human P1 artificial chromosome (PAC) library using primer pairs specific for the human type I hair keratins hHa3-II or hHa6, led to the isolation of two PAC clones, which covered 190 kilobase pairs (kbp) of genomic DNA and contained nine human type I hair keratin genes, one transcribed hair keratin pseudogene, as well as one orphan exon. The hair keratin genes are 4-7 kbp in size, exhibit intergenic distances of 5-8 kbp, and display the same direction of transcription. With one exception, all hair keratin genes are organized into 7 exons and 6 positionally conserved introns. On the basis of sequence homologies, the genes can be grouped into three subclusters of tandemly arranged genes. One subcluster harbors the highly related genes hHa1, hHa3-I, hHa3-II, and hHa4. A second subcluster of highly related genes comprises the novel genes hHa7 and hHa8, as well as pseudogene PsihHaA, while the structurally less related genes hHa6, hHa5, and hHa2 are constituents of the third subcluster. As shown by reverse transcription-polymerase chain reaction, all hair keratin genes, including the pseudogene, are expressed in the human hair follicle. The transcribed pseudogene PsihHaA contains a premature stop codon in exon 4 and exhibits aberrant pre-mRNA splicing. Evolutionary tree construction reveals an early divergence of hair keratin genes from cytokeratin genes, followed by the segregation of the genes into the three subclusters. We suspect that the 190-kbp domain contains the entire complement of human type I hair keratin genes.

Amino Acid Sequence↗
PubMed1998

Economic considerations of the use of new anesthetics: a comparison of propofol, sevoflurane, desflurane, and isoflurane.

UNLABELLED: Cost control in anesthesia is no longer an option; it is a necessity. New anesthetics have entered the market, but economic differences in comparison to standard anesthetic regimens are not exactly known. Eighty patients undergoing either subtotal thyroidectomy or laparoscopic cholecystectomy were randomly divided into four groups, with 20 patients in each group. Group 1 received propofol 1%/sufentanil, Group 2 received desflurane/sufentanil, Group 3 received sevoflurane/sufentanil, and Group 4 received isoflurane/sufentanil (standard anesthesia) for anesthesia. A fresh gas flow of 1.5-2 L/min and 60% N2O in oxygen was used for maintenance of anesthesia, and atracurium was given for muscle relaxation. Concentrations of volatile anesthetics, propofol, and sufentanil were varied according to the patient's perceived need. Isoflurane, desflurane, and sevoflurane consumption was measured by weighing the vaporizers with a precision weighing machine. Biometric data, time of surgery, and time of anesthesia were similar in the four groups. Times for extubation and stay in the postanesthesia care unit (PACU) were significantly longer in the isoflurane group. Use of sufentanil and atracurium did not differ among the groups. Propofol patients required fewer additional drugs in the PACU (e.g., antiemetics), and thus showed the lowest additional costs in the PACU. Total (intra- and postoperative) costs were significantly higher in the propofol group ($30.73 per patient; $0.24 per minute of anesthesia). The costs among the inhalational groups did not differ significantly (approximately $0.15 per minute of anesthesia). We conclude that in today's climate of cost savings, a comprehensive pharmacoeconomic approach is needed. Although propofol-based anesthesia was associated with the highest cost, it is doubtful whether the choice of anesthetic regimen will lower the costs of an anesthesia department. IMPLICATIONS: Cost analysis of anesthetic techniques is necessary in today's economic climate. Consumption of the new inhaled drugs sevoflurane and desflurane was measured in comparison to a standard anesthetic regimen using isoflurane and an IV technique using propofol. Propofol-based anesthesia was associated with the highest costs, whereas the costs of the new inhaled anesthetics sevoflurane and desflurane did not differ from those of a standard, isoflurane-based anesthesia regimen.

Anesthetics, Inhalation↗
PubMed1997

Intestinal bacterial overgrowth and bacterial translocation in cirrhotic rats with ascites.

BACKGROUND/AIMS: Translocation of indigenous bacteria from the gut lumen of cirrhotic animals to mesenteric lymph nodes appears to be an important step in the pathogenesis of spontaneous bacterial peritonitis. However, the sequence of events leading to translocation remains unclear. One of the most predictable risk factors for translocation is overgrowth of gut bacterial flora. The present study was designed to compare the intestinal aerobic bacterial flora of cecal stools at the time of sacrifice between cirrhotic and normal rats and to evaluate the role of intestinal aerobic bacterial overgrowth in bacterial translocation in cirrhotic rats. METHODS: Thirty-five male Sprague-Dawley rats with carbon tetrachloride-induced cirrhosis and ascites and 10 normal rats were included in this study. Cirrhotic rats were sacrificed when ill and samples of ascitic fluid, mesenteric lymph nodes and cecal stool were taken for detecting quantitatively aerobic bacteria. RESULTS: Total intestinal aerobic bacterial count in cecal stool at the time of sacrifice was significantly increased in cirrhotic rats with bacterial translocation with or without spontaneous bacterial peritonitis compared to cirrhotic rats without bacterial translocation (p<0.001 and p<0.001, respectively) and to normal rats (p<0.001 and p<0.001, respectively). Of the 42 species of bacteria translocating to the mesenteric lymph nodes, 41 (97.6%) were found in supranormal numbers in the stool at the time of sacrifice. CONCLUSIONS: Carbon tetrachloride-induced cirrhotic rats with bacterial translocation have increased total intestinal aerobic bacteria count, and intestinal bacterial overgrowth appears to play an important role in bacterial translocation in this experimental model of cirrhosis in rats.

Animals↗
PubMed1995

Food-initiated outbreak of methicillin-resistant Staphylococcus aureus analyzed by pheno- and genotyping.

An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) involving 27 patients and 14 health-care workers (HCW) was studied. The outbreak started in the hematology unit of the University Hospital Rotterdam, Dijkzigt, The Netherlands, and spread to the surgical unit. Twenty-one patients (77.8%) developed clinical disease, and five died. Subsequently, MRSA was detected in food and in the throat of one of the HCW who prepared food for hematology patients. Food contaminated by an HCW most likely caused the first case of MRSA septicemia. This route of transmission has not been described before. The outbreak strain was probably transmitted to the surgical unit by a colonized nurse, where it caused an explosive outbreak. Airborne probably transmitted to the surgical unit by a colonized nurse, where it caused an explosive outbreak. Airborne MRSA transmission played an important role in disseminating the organism. The outbreak was controlled within 6 months by intensifying surveillance, temporarily closing the affected wards, treating carriers, and instituting an MRSA ward outside the hospital. Phage typing, insertion sequence probing, protein A gene typing, and DNA fingerprinting by PCR revealed that all outbreak-related isolates were identical. By pulsed-field gel electrophoresis, all but one of the outbreak-related isolates were determined to be identical. Protein A gene typing identified numerous (11) repeat units in all outbreak-related isolates, which supports the suggestion that the outbreak strain may have been more virulent and more transmissible than other MRSA strains. Pheno- and genotyping studies underlined the value of DNA fingerprinting methods for investigation of MRSA epidemiology. Optimal discriminatory power was achieved by combining the results of four genotyping methods.

Base Sequence↗
PubMed1994

Inhibition by lead of the calcium plateau current at mouse motor nerve endings.

The inhibition by lead of motor terminal calcium plateau signals has been studied using extracellular, perineuronal electrodes applied to the M. triangularis sterni preparation of the mouse. The long-lasting calcium pateau signal induced by 3,4-DAP (250 mumol) and TEA (10 mmol) blockade of presynaptic potassium channels was irreversibly blocked by micromolar lead concentrations in a concentration-dependent manner. These results suggest that lead antagonizes neuronal calcium channels involved in transmitter release from motor nerve terminals.

Action Potentials↗
PubMed1993

G-protein-effector coupling: a real-time light-scattering assay for transducin-phosphodiesterase interaction.

We describe a real-time assay for the interaction of the G-protein of retinal rods, transducin (Gt), with its effector, cGMP phosphodiesterase (PDE). The purified proteins were recombined with isolated rod disk membranes. Reactions were triggered by flash photolysis of the receptor rhodopsin, and monitored by changes of near-infrared light scattering (LS signals). PDE-related LS signals from membrane preparations have been described by others [Caretta, A., & Stein, P. J. (1986) Biochemistry 25, 2335-2341; Bennett, N., & Clerc, A. (1992) Biochemistry 31, 1858-1866]. In the present study, the previous overall light-scattering (turbidity) approach was improved by a specific optical setup and millisecond time resolution. This allowed isolation of a fast "PDE signal" which monitors Gt-PDE interaction on the membrane and in real time. The assignment to the reaction is made by the following observations: (i) preactivation of PDE by purified G alpha GTP gamma S gradually suppresses the signal; (ii) the peak amplitude of the signal is stoichiometric with respect to both Gt and PDE; and (iii) the rise and delay time fit into a kinetic model for a reaction of activated Gt (G*). A comparative investigation, relating the PDE signal with Gt activation and PDE enzymatic activity, led to the following results: (i) the apparent dissociation constant for the interaction of G* with the first binding site on membrane-bound PDE is less than 2.5 nM; (ii) the time interval between formation of G* and its interaction with PDE is less than 5 ms; (iii) membrane-bound PDE, even in its preactivated form, slows the release of G* from the membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1993

Relationship of insulin secretory pulses to sex hormone-binding globulin in normal men.

Insulin has emerged as a regulator of sex hormone-binding globulin (SHBG) production in vitro and in vivo. A role for insulin in regulating SHBG exists in insulin resistant states such as obesity and polycystic ovary syndrome. The relationship of in vivo insulin secretion rates to SHBG levels in healthy normal men is less well documented. Hepatic synthesis of SHBG may be influenced by quantitative insulin exposure as well as qualitative characteristics such as frequency and amplitude of insulin secretory pulses. The present study was undertaken to assess these relationships in 10 normal men. Adiposity was determined by the body mass index and fat distribution by the waist hip ratio. Peripheral insulin sensitivity was determined by the euglycemic clamp technique at an insulin infusion rate of 287 pmol/min.m2. SHBG levels were determined in the fasting state by RIA. Arterialized venous samples for C-peptide were obtained every 2 min for 90 min in the basal state. Individual C-peptide kinetics were derived after a bolus injection of biosynthetic human C-peptide and a previously validated two compartmental model. Insulin secretion rates at each time point were calculated using the plasma C-peptide values and the C-peptide kinetics. Insulin secretion rates were unrelated to SHBG concentrations (r = -0.29, P > 0.05). The insulin secretory pulse interval had a significant positive association with SHBG levels (r = 0.86, P < 0.05). Insulin secretory pulse amplitude, body mass index, waist hip ratio, and peripheral insulin sensitivity were not associated with SHBG concentrations in a regression analysis. We postulate that insulin secretory pulse frequency may be an important determinant of SHBG synthesis in normal man.

Adipose Tissue↗
PubMed1989

High-flux synthetic versus cellulosic membranes for beta 2-microglobulin removal during hemodialysis, hemodiafiltration and hemofiltration.

Efficient removal of beta 2 microglobulin (beta 2-M) in end-stage renal failure patients is a continuing preoccupation, as the incidence and severity of dialysis-associated amyloidosis are increasing. To evaluate comparative beta 2-M removal we studied six stable end-stage renal failure patients during high-flux 3-h haemodialysis, haemodia-filtration, and haemofiltration, using acrylonitrile, cellulose triacetate, polyamide and polysulphone capillary devices. The reduction of plasma beta 2-M, total removal in ultrafiltrate/dialysate, and beta 2-M sieving coefficients were measured by RIA. The results suggest that convection plays the major role in beta 2-M removal when high-flux synthetic membranes are used in combination with high blood flow rates. In contrast, using the cellulose triacetate membrane under investigation, beta 2-M removal is diminished when ultrafiltration rates are increased. Accordingly, in any future prospective study on the role of beta 2-M retention in the amyloidogenesis, it is recommended that high-flux synthetic membranes be employed rather than the type of high-flux cellulosic membranes used in this study. The modality with which these synthetic membranes are used is probably less important, as long as maximum convective transport rates are obtained. Under present conditions, this will imply haemofiltration or haemodiafiltration rather than haemodialysis.

Cellulose↗
PubMed1987

[Surgery of the remaining carotid artery].

Seven patients with unilateral arterial carotid occlusion and contralateral arterial carotid stenosis in the neck are reported. Authors perform an extra-cranial to intra-cranial anastomosis on the occluded side prior to realize endarterectomy on the stenosed side. This policy obviates the need of an internal vascular shunt during temporary occlusion of I.C.A.

Aged↗
PubMed1986

Health needs and concerns of male adolescents.

Lifestyle factors established within the family help determine health-care functioning. Adolescents first may be challenged to meet their own health needs as freshmen in college. A 153-item questionnaire was utilized to examine concerns in the areas of alcohol and other drug use, auto safety, weight and dieting, smoking, sexuality, coping and stress, and selection and utilization of health-care services. One hundred fifty-nine male college students responded. Major problems with alcohol use, auto safety, weight control, stress and sexuality were identified. Positive lifestyle factors that were strongly supported included regular exercise, nonsmoking, regular medical and dental checkups, and the development of some support systems to cope with stress. Health-care services designated by respondents to meet their own needs were significantly different from those services they pointed out as needed for their peers.

Adolescent↗
PubMed1985

[Respiratory depression after intrathecal injection of morphine: value of in situ naloxone].

A case of delayed respiratory depression following an intrathecal injection of hyperbaric morphine hydrochloride is reported. This injection was made during a lumbar myelography in a 60 year old patient suffering from metastatic epiduritis unrelieved by oral or parenteral drugs. The differences in densities between the CSF, hyperbaric opiate solution and contrast medium explain the migration of the morphine hydrochloride from the lumbar thecal space to the basal cisternae, giving a fall in the responsiveness to CO2 of the brain stem respiratory centres. Parenteral naloxone did not reverse this ventilatory depression. Only the myosis and the analgesia disappeared. After 16 h of various attempts of reversal by parenteral injections, an intrathecal injection of naloxone was tried. This small dose (0.1 mg), given intrathecally, resulted in a prompt return to normal of respiratory function.

Anesthesia, Spinal↗
PubMedDate not supplied

Infraclavicular block with lateral approach and nerve stimulation: extent of anesthesia and adverse effects.

BACKGROUND AND OBJECTIVES: The infraclavicular approach to the brachial plexus is little used despite theoretical advantages of the technique. Using a vertical paracoracoid approach, we assessed the extent of the sensory block and the incidence of adverse effects. METHODS: After obtaining informed consent, 100 patients undergoing surgical procedures distal to the elbow were evaluated. The block was performed using a peripheral nerve stimulator. The puncture site was located in the infraclavicular fossa; the direction of the insulated needle was perpendicular to the skin. Motor response was sought in the hand or wrist at < or = 0.6 mA. A total of 40 mL of 1.5% mepivacaine was administered as a single injection. The sensory block was evaluated every 5 minutes for 30 minutes before surgery in the cutaneous distribution of terminal branches of the brachial plexus. RESULTS: When one considers the cutaneous distributions of the median, ulnar, radial, and musculocutaneous nerves, the success rate was 89% for surgery without need for additional peripheral nerve blocks or general anesthesia. In contrast, cutaneous areas innervated by the axillary and medial cutaneous nerves were rarely anesthetized. We were unable to demonstrate a correlation between the intensity of the stimulation and the success of the block. On the other hand, a correlation was found between tourniquet sensation and the absence of anesthesia of the medial cutaneous nerve of the arm. Local anesthetic toxicity, Horner's syndrome, and vascular puncture were respectively observed in 1%, 4%, and 5% of cases. The depth of the needle introduction was correlated with the body mass index (P <.001; r =.63). CONCLUSION: Single injection infraclavicular block, using a vertical paracoracoid approach, appears suitable for surgery distal to the elbow. Selective anesthesia of the medial cutaneous nerve is useful in improving tolerance of the tourniquet.

Anesthetics, Local↗