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A Burger

Publications and source records attributed to A Burger.

At least 37 records · Page 2Linked to original sources
PubMed2000

Polymorphism of tedisamil dihydrochloride.

The results of studies on tedisamil dihydrochloride in the solid state demonstrate that the compound occurs in three polymorphic forms. The three modifications have been characterized by thermomicroscopy, differential scanning calorimetry (DSC), vibrational spectroscopy, solid-state nuclear magnetic resonance (NMR), and X-ray powder diffractometry (XRPD). The thermodynamic relationships are illustrated in a semischematic energy/temperature diagram that gives information about the relative stability and physical properties of the three modifications between 0 K and the melting temperatures. The three modifications are enantiotropically related. Modification II, the material obtained during manufacturing, is the thermodynamically stable crystal form at 20 degrees C. The thermodynamic transition point of mod II with I (instant melting point: 248-250 degrees C) is between 100 and approximately 140 degrees C (DeltaH(t,II/I) = 4.4+/-0.8 kJ/mol (95% CI)). A phase transition of mod II (probably into mod III) was detected thermomicroscopically at about -180 degrees C. The thermodynamic transition point of mod III with I was determined to be at -9 to -6 degrees C. Because mods I and III are thermodynamically and kinetically unstable at ambient conditions, these crystal forms are of analytical interest.

Anti-Arrhythmia Agents↗
PubMed2000

Identification and characterization of the mre gene region of Streptomyces coelicolor A3(2).

During a search for new differentiation factors in Streptomyces coelicolor A3(2), a locus at 11 o'clock on the S. coelicolor map was identified which harbours several genes that show extensive similarity to cell division and differentiation genes from Escherichia coli and Bacillus subtilis. From the sequence data it was concluded that the region contains the genes mireB, mreC, mreD (murein formation gene cluster E), pbp83 (high-molecular-weight penicillin-binding protein) and sfr (member of the spoVE/ftsW/rodA family). Mre gene products are reported to be responsible for determining cell shape in E. coli and Bacillus. The S. coelicolor mreC gene was inactivated by gene disruption, resulting in mutants which showed significant growth retardation in comparison to the wild type. Inactivation of the mreB gene was incompatible with viability, and thus mreB represents a Streptomyces cell division gene that is essential for survival. Promoter-probe experiments led to the identification of an operon structure, with promoters located upstream of mreB, pbp83 and sfr. Detailed studies of mreB transcription revealed the existence of three promoters; two of them are constitutively transcribed, whereas the third is developmentally regulated.

Amino Acid Sequence↗
PubMed2000

Polymorphism and preformulation studies of lifibrol.

Three polymorphic modifications of lifibrol, a novel cholesterol-lowering drug substance, were detected and thoroughly investigated and characterized by thermomicroscopy, DSC, IR-spectroscopy and X-ray powder diffractometry. Mod. I (m.p. 142 degrees C) and mod. II (m.p. 135 degrees C) are stable. Furthermore, true densities, solubilities as function of temperature and pH-value as well as the behavior of the crystal forms under the influence of humid air were determined. The three modifications show distinct differences by IR-spectroscopy, through which a distinction even is possible. The density of mod. I is lower than that of mod. II. The transition of mod. II into mod. I corresponds to an endothermic reaction; from this it follows, that between mod. I and mod. II enantiotropism exists. Mod. II is at 20 degrees C by about 44% less soluble as mod. I. Mod. III, which only can be produced by crystallizing the glassy solidified melt, has a negative heat of transition. That means that mod. III behaves monotropic with regard to both enantiotropic modifications I and II. Mod. I exists in form of small lamellae, mostly of irregular forms. Mod. II consists of rhombohedron grains. Because of this difference in habit, for mod. II one can predict the best properties in case of pressing tablets.

Anticholesteremic Agents↗
PubMed2000

[Pituitary necrosis after spinal anesthesia : a case report].

Spinal anesthesia was administered to a patient for the surgical reduction of an inguinal hernia. However, the procedure was complicated by corticotropic insufficiency secondary to the necrosis of a non-secretory hypophyseal adenoma. The clinical presentation is discussed here together with both medical and neurosurgical managements. Etiology and pathophysiological mechanisms of this complication are analyzed in accordance with the most recent of the literature.

Adenoma↗
PubMed1999

Prospective evaluation of autonomic dysfunction in aggressive management of diabetic microangiopathy.

Twenty-six type I diabetic nephropathy patients in a rigorous schedule for glucose control to preserve kidney function were studied to determine autonomic functional changes during 18 months. Intercurrent and nonrelated acute illness, withdrawal from the study for personal reasons, or failure to undergo testing on schedule resulted in complete data at 1 year for 26 of the original 41 patients enrolled, 24 patients completing a further 6 months. Glycohemoglobin A1c dropped for the total group from 9.0 to 7.9 at 6 months, 8.0 at 12 months, and 8.1 at 18 months (P<.01). Autonomic function tests revealed baseline results that were below the anticipated normals for age in 38% to 56% of patients. Timed ventilatory heart rate variations measured for the total group were 1.11, 1.13, 1.10, and 1.09 (normal > or =1.20). Valsalva heart rate variations for the total group were 1.27, 1.30, 1.255, and 1.35 (normal > or =1.50). Assumption of upright posture-related heart rate variations for the total group were 1.10, 1.07, 1.07, and 1.06 (normal > or =1.20). Mean arterial pressure day/night ratios for the total group were 1.04, 1.05, 1.05, and 1.08 (normal > or =1.10). Group analysis based on differences in insulin treatment programs, levels of blood pressure, and levels of renal function revealed no significant differences from the total group or companion groups during 18 months. Patients with a glycohemoglobin A1c of <8.0% were more likely to normalize mean arterial pressure day/night ratios than those with glycohemoglobin A1c > or =8.0%. We conclude that aggressive glucose control in diabetic patients with proteinuria for a period of 18 months resulted in a reproducible pattern of autonomic function tests during that period of time with neither worsening nor improvement. The restoration of day/night mean arterial pressure variation in a minority of patients should be studied with a larger cohort.

Adult↗
PubMed1999

An evaluation of the transition temperature range of super-elastic orthodontic NiTi springs using differential scanning calorimetry.

Differential scanning calorimetry (DSC) was used to determine the transition temperature ranges (TTR) of four types of super-elastic orthodontic nickel-titanium coil springs (Sentalloy). A knowledge of the TTR provides information on the temperature at which a NiTi wire or spring can assume superelastic properties and when this quality disappears. The spring types in this study can be distinguished from each other by their characteristic TTR during cooling and heating. For each tested spring type a characteristic TTR during heating (austenite transformation) and cooling (martensite transformation) was evaluated. The hysteresis of the transition temperature, found between cooling and heating, was 3.4-5.2 K. Depending on the spring type the austenite transformation started (As) at 9.7-17.1 degrees C and finished (Af) at 29.2-37 degrees C. The martensite transformation starting temperature (Ms) was evaluated at 32.6-25.4 degrees C, while Mf (martensite transformation finishing temperature) was 12.7-6.5 degrees C. The results show that the springs become super-elastic when the temperature increases and As is reached. They undergo a loss of super-elastic properties and a rapid decrease in force delivery when they are cooled to Mf. For the tested springs, Mf and As were found to be below room temperature. Thus, at room temperature and some degrees lower, all the tested springs exert super-elastic properties. For orthodontic treatment this means the maintenance of super-elastic behaviour, even when mouth temperature decreases to about room temperature as can occur, for example, during meals.

Body Temperature↗
PubMed1999

Sympathomimetic effects of MIBG: comparison with tyramine.

UNLABELLED: Because nothing is known about whether metaiodobenzylguanidine (MIBG) has tyramine-like actions, the sympathomimetic effects of MIBG were determined in the isolated rabbit heart and compared with those of tyramine. METHODS: Spontaneously beating rabbit hearts were perfused with Tyrode's solution (Langendorff technique; 37 degrees C; 26 mL/min), and the heart rate as well as the norepinephrine and dopamine overflow into the perfusate was measured before and after doses of MIBG or tyramine (0.03-10 micromol) given as bolus injections (100 microL) into the aortic cannula. Km and Vmax values for the neuronal uptake (uptake1) of 125I-MIBG and 14C-tyramine were obtained in human neuroblastoma (SK-N-SH) cells. The Ki of MIBG for inhibition of the 3H-catecholamine uptake mediated by the vesicular monoamine transporter was determined in membrane vesicles obtained from bovine chromaffin granules and compared with the previously reported Ki value for tyramine determined under identical experimental conditions. RESULTS: By producing increases in heart rate and norepinephrine overflow, both compounds had dose-dependent sympathomimetic effects in the rabbit heart. MIBG was much less effective than tyramine in increasing heart rate (maximum effect 59 versus 156 beats/min) and norepinephrine overflow (maximum effect 35 versus 218 pmol/g). Tyramine also caused increases in dopamine overflow, whereas MIBG was a poor dopamine releaser. At a dose of 10 micromol, the increase in heart rate lasted more than 60 min after MIBG and about 20 min after tyramine injection. Accordingly, the norepinephrine overflow caused by 10 micromol MIBG and tyramine declined with half-lives of 57.8 and 2.2 min, respectively. The effects of both drugs were drastically reduced in hearts exposed to 2 micromol/L desipramine. The kinetic parameters characterizing the saturation of neuronal uptake by 125I-MIBG and 14C-tyramine were similar for the two compounds: Km values of MIBG and tyramine were 1.6 and 1.7 micromol/L, respectively, and Vmax values of MIBG and tyramine were 43 and 37 pmol/mg protein/min, respectively. However, in inhibiting the vesicular 3H-catecholamine uptake, MIBG was eight times less potent than tyramine. CONCLUSION: MIBG is much less effective than tyramine as an indirect sympathomimetic agent. This is probably a result of its relatively low affinity for the vesicular monoamine transporter and explains the relatively poor ability of the drug to mobilize norepinephrine stored in synaptic vesicles. The long duration of MIBG action results primarily from the drug not being metabolized by monoamine oxidase. The sympathomimetic effects of MIBG described here are not likely to come into play in patients given diagnostic or common therapeutic doses of radioiodinated MIBG.

3-Iodobenzylguanidine↗
PubMed1998

[Amiodarone and thyroid function: clinical implications].

World-wide, the incidence of amiodarone-induced thyroid dysfunction is estimated to be between 2% and 24%. More than 50% of patients who receive long-term amiodarone have abnormal results on thyroid function tests. However, most of these patients are euthyroid. In a euthyroid amiodarone-treated patient, an increase in serum thyroxine levels (total and free) and in serum reverse T3 levels and a decrease in serum T3 levels (total and free), are observed. TSH levels are within the normal range with chronic treatment (more than 3 months). The aim of this study was to identify the frequency of amiodarone prescription by cardiologists, to learn about their clinical practice in screening for thyroid dysfunction, and to formulate guidelines for clinical investigation of thyroid function before and during amiodarone treatment. A questionnaire was sent to 27 cardiologists in private practice in the Geneva area and to 12 cardiologists in Geneva University Hospital (19 and 7 questionnaires returned respectively). Cardiologists in private practice prescribe amiodarone quite frequently (once to twice per month and more). Clinical investigation prior to treatment involves history (95%), clinical examination (63%) or thyroid function tests (37% routinely, 16% where there is clinical suspicion of thyroid dysfunction). Thyroid function is investigated by determination of TSH (100%), free T4 (68%), free T3 (50%), total T3 (32%) or total T4 (26%). Antithyroid antibodies are measured only by 10% of the cardiologists in private practice. Cardiologists would restrict amiodarone prescription in cases of clinical hyperthyroidism (90%), clinical hypothyroidism (74%), in the presence of goitre in a hyper- or hypothyroid patient (79 and 63% respectively), and if antithyroid antibodies were positive (32%). During amiodarone treatment 84% of cardiologists in private practice repeat thyroid function tests occasionally and 16% only in the presence of clinical signs. Hypothyroidism is a reason for withdrawing amiodarone treatment for 58% of the cardiologists and 37% would prescribe substitution. Hyperthyroidism is a reason for immediately suspending treatment for 90% of the cardiologists, only 5% would continue and 16% would prescribe antithyroid drugs. In conclusion, there is considerable divergence of opinion among cardiologists concerning investigation and interpretation of thyroid function before and during amiodarone treatment. Simple and practicable guidelines are needed.

Amiodarone↗
PubMed1998

Analysis of a Streptomyces coelicolor A3(2) locus containing the nucleoside diphosphate kinase (ndk) and folylpolyglutamate synthetase (folC) genes.

A 3.6-kb DNA fragment from Streptomyces coelicolor A3(2) with the genes valS probably encoding a valyl-tRNA synthetase, folC encoding folylpolyglutamate synthetase, and ndk encoding a nucleoside diphosphate kinase was analysed. folC and ndk are separated by a small open reading frame of unknown function, orfX. The deduced folC gene product is a protein of 46,677 Da whose sequence is similar to other folylpolyglutamate synthetases and folylpolyglutamate synthetase-dihydrofolate synthetases from both Gram-positive and Gram-negative bacteria. After cloning folC behind the lacZ promoter, the Streptomyces folC complemented a folC mutant of Escherichia coli. An essential function for Streptomyces folC was suggested by the fact that it could not be mutated using a conventional gene disruption technique.

Amino Acid Sequence↗
PubMed1998

Breast cancer genome anatomy: correlation of morphological changes in breast carcinomas with expression of the novel gene product Di12.

To determine which genes may be activated or inactivated during breast cancer development, we employed two cloning strategies (subtractive hybridization and differential display) using RNA samples from a human breast tumor and its matching normal breast cell line. Of 950 clones isolated, 102 cDNA inserts were analysed by DNA sequencing and database searching. We found 30 clones that were obviously unidentified, with no significant homology to any listed human gene. We focused upon one of the novel genes, Di12, that is differentially expressed as a 1.35 kb RNA in breast cancer tissues and cell-lines, and in several normal tissues. A full length cDNA of this gene was cloned, and its DNA sequence revealed an open reading frame of 339 amino acids. Antibodies to the ten N-terminal amino acids were developed to investigate the expression of Di12 in breast cancer cell-lines and tumors. The Di12 protein was found in tissue sections of infiltrating ductal carcinomas (IDCs), but not in benign or normal breast specimens. RT-PCR analysis confirmed expression of Di12 in 80% of infiltrating ductal carcinomas (IDCs). As IDC constitutes approximately 70% of breast cancers seen clinically, the level of Di12 expression may be predictive of disease progression.

Amino Acid Sequence↗
PubMed1998

Species differences in the glutathione transferase GSTT1-1 activity towards the model substrates methyl chloride and dichloromethane in liver and kidney.

Glutathione transferase (GST) GSTT1-1 is involved in the biotransformation of several chemicals widely used in industry, such as butadiene and dichloro methane DCM. The polymorphic hGSTT1-1 may well play a role in the development of kidney tumours after high and long-term occupational exposure against trichloroethylene. Although several studies have investigated the association of this polymorphism with malignant diseases little is known about its enzyme activity in potential extrahepatic target tissues. The known theta-specific substrates methyl chloride (MC) dichloromethane and 1,2-epoxy-3-(p-nitrophenoxy)propane (EPNP) were used to assay GSTT1-1 activity in liver and kidney of rats, mice, hamsters and humans differentiating the three phenotypes (non-conjugators, low conjugators, high conjugators) seen in humans. In addition GSTT1-1 activity towards MC and DCM was determined in human erythrocytes. No GSTT1-1 activity was found in any tissue of non-conjugators (NC). In all organs high conjugators (HC) showed twofold higher activity towards MC and DCM than low conjugators (LC). The activity in human samples towards EPNP was too close to the detection limit to differentiate between the three conjugator phenotypes. GSTT1-1 activity towards MC was two to seven-times higher in liver cytosol than in kidney cytosol. The relation for MC between species was identical in both organs: mouse > HC > rat > LC > hamster > NC. In rats, mice and hamsters GSTT1-1 activity in liver cytosol towards DCM was also two to seven-times higher than in the kidney cytosol. In humans this activity was twice as high in kidney cytosol than in liver cytosol. The relation between species was mouse > rat > HC > LC > hamster > NC for liver, but mouse > HC > LC/rat > hamster/NC for kidney cytosol. The importance to heed the specific environment at potential target sites in risk assessment is emphasized by these results.

Animals↗
PubMed1998

An internet-accessible database of mouse developmental anatomy based on a systematic nomenclature.

This paper reports an internet-accessible database of mouse developmental anatomy (DMDA) that currently holds a hierarchy of the names and synonyms of the tissues in the first 22 Theiler stages of development (E1-E13.5), together with other appropriate information. The purposes of the database are to provide, first, a nomenclature for analyzing normal and mutant mouse anatomy, and second a language for inputting, storing and querying gene-expression and other spatially organized data. DMDA currently contains some 6900 named and staged tissues (e.g. 360 and 1161 tissues in Theiler stage (TS) 14 (E9) and TS22 (E13.5) embryos). DMDA will be extended to include further lineage and other data when it becomes available. The database can be interactively accessed over the internet using either a Java or a non-Java WWW browser at http://genex.hgu.mrc.ac.uk/.

Animals↗
PubMed1998

Molecular and cellular basis of radiation fibrosis.

PURPOSE: Recent data from the literature and the experimental work of the authors clearly indicate that TGF-beta1 is a key modulator of cellular events, for example, induction of terminal differentiation, resulting in radiation-induced fibrosis. Therefore, the present study analysed which cellular processes induced by exogenously added TGF-beta could be responsible for the induction, development and manifestation of the fibrotic phenotype in culture. MATERIALS AND METHODS: Rat lung fibroblast cultures (passage 1) were used. As a function of treatment with TGF-beta and/or anti-TGF-beta-antibody, the clonogenic activity and differentiation pattern were analysed by colony-formation assays. RESULTS: It could be demonstrated that treatment of rat lung progenitor fibroblasts with TGF-beta1 resulted in a pronounced shift in the differentiation pattern, i.e. induction of post-mitotic fibrocytes. This TGF-beta1-dependent terminal differentiation could be abolished by simultaneous treatment with a neutralizing antibody directed against TGF-beta1. CONCLUSIONS: The data presented indicate that TGF-beta1 is one major candidate mediating the accelerated terminal differentiation of progenitor fibroblasts to post-mitotic functional fibrocytes, which results in the fibrotic phenotype of this cell system.

Animals↗
PubMed1998

Helicobacter pylori induces apoptosis in mucosal lymphocytes in patients with gastritis.

BACKGROUND: Previous studies suggest that Helicobacter pylori (H. pylori) induces apoptosis and compensatory hyperproliferation in gastric epithelial cells possibly explaining the carcinogenic capacity of the bacteria. The aim of this study was to measure the effect of H. pylori on apoptosis of gastric lymphoid cells in view of the development of gastric lymphoma. METHODS: 16 H. pylori-positive and 19 H. pylori-negative individuals were enrolled. Single cell suspensions were prepared from antral biopsies and apoptosis was measured by staining with the TUNEL-assay and the fluorochrome Hoechst 33342. Lymphocyte subsets were simultaneously identified by immunocytochemistry. RESULTS: The apoptotic index of all gastric mucosal cells was significantly higher in H. pylori-positive mucosa compared to negative controls. Additionally, H. pylori-infected patients showed a significant increase in apoptosis of mucosal B-lymphocytes. Apoptosis of T cells and plasma cells was unaffected by H. pylori. CONCLUSION: H. pylori induces apoptosis in mucosal B cells which might be important in the development of gastritis and possibly B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT).

Adult↗
PubMed1998

[Effectiveness of partial inpatient rehabilitation from the patient's viewpoint. Results of an evaluation of a partial hospitalization model project at the Ichenhausen specialty clinic].

Partial-hospitalization rehabilitation is a relatively recent form of rehabilitation, which, as opposed to the ambulatory approach, comprises the entire programme available for inpatient medical rehabilitation except for accommodation and full board. Great expectations are attached to partial hospitalization: it is supposed to cost less than a comparable in-patient measure but matching in terms of quality. However, hardly any empirical data exist so far concerning the effects partial hospitalization rehabilitation is having in these respects. The present article seeks to answer the question of whether from a patient perspective, the outcome quality of this new model is comparable to that of the classical full-hospitalization programmes. In terms of methodology, questionnaires were used to raise the necessary data from two independent samples (i.e., partial vs. full hospitalization) of former orthopaedic rehabilitees of Fachklinik Ichenhausen (Bavaria). Data analysis included some 205 patient questionnaires (57% return rate). High agreement was found among the two groups concerning outcome evaluation, subjective health and patient satisfaction. From a patient perspective, rehabilitation outcome on the majority of variables considered, even is judged slightly better for partial hospitalization patients than for the inpatient comparison group. As none of these results reach statistical significance, these minor differences should however not be overrated. While partial-hospitalization, rehabilitation, hence, has turned out an option which matches traditional full-hospitalization programmes in terms of quality, too great expectations nevertheless are unwarranted: Partial-hospitalization rehabilitation is no general alternative to inpatient programmes as it will realistically be suitable for a small percentage of orthopaedic patients only, hence be unable to replace full-hospitalization programmes to any major extent. Undoubtedly, however, it is apt to contribute to greater flexibility and needs orientation among the services and programmes available in rehabilitation, and may thus be considered a valuable approach for complementing inpatient and ambulatory forms of rehabilitation.

Day Care, Medical↗
PubMed1998

Healthy valley 2000.

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Community-Institutional Relations↗