Biomedical subjects

A Schmid

Publications and source records attributed to A Schmid.

At least 109 records · Page 6Linked to original sources

PubMed1998

Control of Ca2+ wave propagation in mouse pancreatic acinar cells.

We have investigated control mechanisms involved in the propagation of agonist-induced Ca2+ waves in isolated mouse pancreatic acinar cells. Using a confocal laser-scanning microscope, we were able to show that maximal stimulation of cells with acetylcholine (ACh, 500 nM) or bombesin (1 nM) caused an initial Ca2+ release of comparable amounts with both agonists at the luminal cell pole. Subsequent Ca2+ spreading to the basolateral membrane was faster with ACh (17.3 +/- 5.4 microns/s) than with bombesin (8.0 +/- 2.2 microns/s). The speed of bombesin-induced Ca2+ waves could be increased up to the speed of ACh-induced Ca2+ waves by inhibition of protein kinase C (PKC). Activation of PKC significantly decreased the speed of ACh-induced Ca2+ waves but had only little effect on bombesin-evoked Ca2+ waves. Within 3 s after stimulation, production of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] was higher in the presence of ACh compared with bombesin, whereas bombesin induced higher levels of diacylglycerol (DAG) than ACh. These data suggest that the slower propagation speed of bombesin-induced Ca2+ waves is due to higher activation of PKC in the presence of bombesin compared with ACh. The higher increase in bombesin-compared with ACh-induced DAG production is probably due to activation of phospholipase D (PLD). Inhibition of the PLD-dependent DAG production by preincubation with 0.3% butanol led to an acceleration of the bombesin-induced Ca2+ wave. In further experiments, we could show that ruthenium red (100 microM), an inhibitor of Ca(2+)-induced Ca2+ release in skeletal muscle, also decreased the speed of ACh-induced Ca2+ waves. The effect of ruthenium red was not additive to the effect of PKC activation. From the data, we conclude that, following Ins(1,4,5)P3-induced Ca2+ release in the luminal cell pole, secondary Ca2+ release from stores, which are located in series between the luminal and the basal plasma membrane, modifies Ca2+ spreading toward the basolateral cell side by Ca(2+)-induced Ca2+ release. Activation of PKC leads to a reduction in Ca2+ release from these stores and therefore could explain the slower propagation of Ca2+ waves in the presence of bombesin compared with ACh.

Acetylcholine↗

PubMed1998

Effect of intracellular pH on acetylcholine-induced Ca2+ waves in mouse pancreatic acinar cells.

We have used fluo 3-loaded mouse pancreatic acinar cells to investigate the relationship between Ca2+ mobilization and intracellular pH (pHi). The Ca2+-mobilizing agonist ACh (500 nM) induced a Ca2+ release in the luminal cell pole followed by spreading of the Ca2+ signal toward the basolateral side with a mean speed of 16.1 +/- 0.3 micron/s. In the presence of an acidic pHi, achieved by blockade of the Na+/H+ exchanger or by incubation of the cells in a Na+-free buffer, a slower spreading of ACh-evoked Ca2+ waves was observed (7.2 +/- 0.6 micron/s and 7.5 +/- 0.3 micron/s, respectively). The effects of cytosolic acidification on the propagation rate of ACh-evoked Ca2+ waves were largely reversible and were not dependent on the presence of extracellular Ca2+. A reduction in the spreading speed of Ca2+ waves could also be observed by inhibition of the vacuolar H+-ATPase with bafilomycin A1 (11.1 +/- 0.6 micron/s), which did not lead to cytosolic acidification. In contrast, inhibition of the endoplasmic reticulum Ca2+-ATPase by 2,5-di-tert-butylhydroquinone led to faster spreading of the ACh-evoked Ca2+ signals (25.6 +/- 1.8 micron/s), which was also reduced by cytosolic acidification or treatment of the cells with bafilomycin A1. Cytosolic alkalinization had no effect on the spreading speed of the Ca2+ signals. The data suggest that the propagation rate of ACh-induced Ca2+ waves is decreased by inhibition of Ca2+ release from intracellular stores due to cytosolic acidification or to Ca2+ pool alkalinization and/or to a decrease in the proton gradient directed from the inositol 1,4, 5-trisphosphate-sensitive Ca2+ pool to the cytosol.

Acetylcholine↗

PubMed1998

Catecholamines, heart rate, and oxygen uptake during exercise in persons with spinal cord injury.

The purpose of this study was to investigate the influence of different injury levels in persons with spinal cord injury (SCI) on epinephrine (Epi) and norepinephrine (NE) at rest and during graded wheelchair exercise and the related changes in heart rate and O2 uptake (VO2). Twenty tetraplegics (Tetra), 10 high-lesion paraplegics (HLPara), 20 paraplegics with SCI below T5 (MLPara), and 18 able-bodied, nonhandicapped persons (AB) were examined. Because of the higher level of interruption of the sympathetic pathways, Tetra persons showed lower Epi and NE at rest and only slight increases during exercise compared with all other groups; the Tetra subjects' impaired cardiac sympathetic innervation caused restricted cardioacceleration and strongly reduced maximal VO2. When compared with AB persons, HLPara had comparable NE but lower Epi levels as a result of partial innervation of the noradrenergic system and denervation of the adrenal medulla. MLPara subjects showed an augmented basal and exercise-induced upper spinal thoracic sympathetic activity compared with AB subjects. The increase in heart rate in relation to VO2 was higher in HLPara because of a smaller stroke volume as a result of venous blood pooling. The different exercise response in persons with SCI is a result of the interruption of pathways in the spinal cord to the peripheral sympathetic nervous system in addition to the motor paralysis.

Adult↗

PubMed1998

Different functions of different eye types in the spider Cupiennius salei.

The Central American hunting spider Cupiennius salei Keys relies mainly on its mechanosensory systems during prey-catching and mating behaviour. The behavioural relevance of its eight eyes has not been studied before, although their optics and sensitivity suggest highly developed visual capabilities. The visual system was examined in a twofold simultaneous-choice experiment. Two targets were presented at a distance of 2 m from the animals, and their walking paths towards the targets were monitored. Spiders showed no preference when choosing between two identical targets, but when choosing between two different targets they strongly preferred a vertical bar to a sloping bar or a V-shaped target. By covering all eyes except the anterior median or posterior median eyes, it could be shown that the spiders were able to detect the targets using any of the eyes. Discrimination between different targets was only possible with the anterior median eyes uncovered, although the visual fields of the anterior median and posterior median eyes overlap completely. It seems most likely that the animals separate visual information in the periphery and therefore that the eyes have different functions. The posterior median eyes support a target-detecting mechanism and the anterior median eyes a target-discrimination mechanism.

Adaptation, Ocular↗

PubMed1998

[Esophageal carcinoma: guidelines in surgical therapy].

According to oncological criteria, resections for esophageal cancer require a combined abdominal and thoracic approach and should include two-field lymphadenectomy. The value of a three-field lymphadenectomy is still under discussion, because this extended lymph node dissection may provide better survival rates for patients with proximal esophageal cancer and positive lymph node stages on the one hand, but will cause increased morbidity, on the other. A neoadjuvant radio- and/or chemotherapy allows down staging in about 50% of patients with advanced esophageal cancer (stage IIB, III or IV). This leads to higher resectability rates, but is not necessarily associated with better survival rates.

Adenocarcinoma↗

PubMed1998

[Radiation dosage of the surgery from intraoperative roentgen procedures: risks and dose management in the operating room].

A prospective study of 24 operative procedures with fluoroscopic guidance was undertaken to measure the radiation exposure of the primary surgeon. The dose received per procedure ranged from 0.6 to 259.3 microSv and was well within the government guidelines. An in vitro study during lateral fluoroscopy proved the position of the surgeon close to the image converter was irradiated with less scatter.

Body Burden↗

PubMed1998

[Fractionated, interstitial postoperative HDR-/PDR-brachytherapy with intraoperatively placed probes--initial experiences with a new radiotherapy modality in treatment of recurrent or non-resectable colorectal carcinomas].

Twenty-eight patients with recurrent (82.1%) and/or noncuratively resected (71.4%) colorectal cancer underwent fractionated interstitial BT (20.1 Gy) by using median 5.6 (3-11) afterloading tubes placed directly on the tumor bed intraoperatively. HDR/PDR BT started 2-3 weeks after multivisceral resection (50%) and was combined with external beam radiation therapy in 96% and with chemotherapy (5-FU/Leucoverin) in 86% of the patients. Though the R0-resection rate before BT was only 28.6% multimodality treatment resulted in a local tumor control rate of 64.3%, a survival rate of 53.6%, and a tumor-free survival rate of 42.9%, in an average of 19.8 months (2-43 months) after BT.

Brachytherapy↗

PubMed1997

Inwardly rectifying, voltage-dependent and resting potassium currents in rat pancreatic acinar cells in primary culture.

1. In exocrine pancreatic acinar cells in primary culture an inwardly rectifying, a voltage-dependent and a permanent resting K+ current were characterized. 2. Inwardly rectifying K+ currents could be elicited by elevation of the extracellular K+ concentration. The K+ inward currents were almost completely blocked by 5 mM Ba2+, whereas 10 mM TEA+ had only a partial effect. 3. Depolarizing voltage steps from negative clamp potentials evoked transient activation of a voltage-dependent K+ current. This voltage-dependent current could be blocked by 10 mM TEA+ and 1 mM 4-aminopyridine, but not by 5 mM Ba2+. 4. Neither the K+ inward rectifier nor the voltage-dependent K+ conductance produced a significant negative cell potential. Stable membrane potentials (-38.7 +/- 2.3 mV, n = 38) could only be recorded on cell clusters (> or = 5 cells). 5. Cell clusters, in contrast to single cells, had a permanent resting K+ conductance in addition to the inward rectifier and the voltage-dependent current. This resting K+ conductance was not blocked by TEA+, Ba2+, 4-aminopyridine or by the chromanol 293B. 6. Cytosolic alkalization by addition of NH4Cl to the bath solution decreased the resting K+ current. In parallel, electrical uncoupling of the cells and breakdown of the resting potential could be observed. The same effects could be produced when the cells were uncoupled by 0.2-1.0 mM n-octanol. It can be concluded that cell coupling is essential for maintenance of stable resting membrane potentials in pancreatic acinar cells.

4-Aminopyridine↗

PubMed1997

Purification and characterization of 2-hydroxybiphenyl 3-monooxygenase, a novel NADH-dependent, FAD-containing aromatic hydroxylase from Pseudomonas azelaica HBP1.

2-Hydroxybiphenyl 3-monooxygenase (HbpA), the first enzyme of 2-hydroxybiphenyl degradation in Pseudomonas azelaica HBP1, was purified 26-fold with a yield of 8% from strain HBP1 grown on 2-hydroxybiphenyl. The enzyme was also purified from a recombinant of Escherichia coli JM109, which efficiently expressed the hbpA gene. Computer densitometry of scanned slab gels revealed a purity of over 99% for both enzyme preparations. Gel filtration, subunit cross-linking, and SDS-polyacrylamide gel electrophoresis showed that the enzyme was a homotetramer with a molecular mass of 256 kDa. Each subunit had a molecular mass of 60 kDa containing one molecule of noncovalently bound FAD. The monooxygenase had a pI of 6.3. It catalyzed the NADH-dependent ortho-hydroxylation of 2-hydroxybiphenyl to 2,3-dihydroxybiphenyl. Molecular oxygen was the source of the additional oxygen of the product. The enzyme hydroxylated various phenols with a hydrophobic side chain adjacent to the hydroxy group. All substrates effected partial uncoupling of NADH oxidation from hydroxylation with the concomitant formation of hydrogen peroxide. 2,3-Dihydroxybiphenyl, the product of the reaction with 2-hydroxybiphenyl, was a non-substrate effector that strongly facilitated NADH oxidation and hydrogen peroxide formation without being hydroxylated and also was an inhibitor. The apparent Km values (30 degrees C, pH 7.5) were 2.8 microM for 2-hydroxybiphenyl, 26.8 microM for NADH, and 29.2 microM for oxygen. The enzyme was inactivated by p-hydroxymercuribenzoate, a cysteine-blocking reagent. In the presence of 2-hydroxybiphenyl, the enzyme was partly protected against the inactivation, which was reversed by the addition of an excess of dithiothreitol. The NH2-terminal amino acid sequence of the enzyme contained the consensus sequence GXGXXG, indicative of the betaalphabeta-fold of the flavin binding site and shared homologies with that of phenol 2-hydroxylase from Pseudomonas strain EST1001 as well as with that of 2,4-dichlorophenol 6-hydroxylase from Ralstonia eutropha.

Amino Acid Sequence↗

PubMed1997

[Long-term follow-up after participation in an integrated group treatment program for patients with intractable musculoskeletal pain].

METHODS: Long-term outcome in terms of well-being, depression and ability to cope was evaluated by means of a mailed questionnaire up to 5 years after participation in an integrated group treatment program for chronic musculoskeletal pain (mostly back pain). Sixty-one completed questionnaires were available for analysis, representing 69% of all 89 participants. RESULTS: Comparison of responders and non-responders yielded no important differences. On the basis of their further need for treatment, their working ability and global rating of outcome, patients were divided into three groups: In 18 cases the situation had further improved, 33 were unchanged and 10 had worsened. Sociodemographic data and pain history did not differ among the three groups. Patients with a favorable outcome scored significantly lower than the rest of the patients on a symptom check list and showed the greatest decrease from pretreatment values (if available). They rated themselves significantly higher on the two-dimensional health locus of control scale and were aware of significantly more factors influencing their pain than were the unimproved (unchanged or worsened) patients. Cognitive-behavioral strategies had been continued long-term by 83.6% of the patients and were rated most helpful. Physical training and at least one relaxation technique were continued in 80.3% of the patients, with a slightly lower rating of helpfulness. Improved patients gave generally higher ratings for helpfulness and applied these strategies also to problems other than pain (e.g. anxiety). CONCLUSIONS: The majority of patients maintained at least two of the self-help strategies over many years and seem to profit from their use. Positive long-term effects on well-being were visible in 30% of all participants, and these were clearly more orientated towards self-control than the unimproved subgroups.

English Abstract↗

PubMed1997

RNA polymerase II holoenzyme recruitment is sufficient to remodel chromatin at the yeast PHO5 promoter.

We examine transcriptional activation and chromatin remodeling at the PHO5 promoter in yeast by fusion proteins that are thought to act by recruiting the RNA polymerase II holoenzyme to DNA in the absence of a classic activating region. These hybrid proteins (e.g., Gal11+Pho4 or Gal4(58-97)+Pho4 in the presence of a GAL11P allele) efficiently activated transcription and remodeled chromatin. Similar chromatin remodeling was observed at a PHO5 promoter deleted for TATA and thus unable to support transcription. We conclude that recruitment of the holoenzyme or associated proteins suffices for chromatin remodeling. We also show that the SWI/SNF complex is required neither for efficient transcription of the wild-type PHO5 nor the GAL1 promoters, and we observe nearly complete chromatin remodeling at PHO5 in the absence of Snf2.

Chromatin↗

PubMed1997

[The multi-point contact (MPC) osteosynthesis plate. 2: Initial clinical results of therapy of forearm fracture with MPC plates].

Plate osteosynthesis is a method of choice in the treatment of forearm fractures with senso-motorical impairment, poorly or non-reduceable, retained, fragmented and open fractures. Dislocated fractures of the forearm frequently cause problems because of their poor reduction and retention. In such cases, exclusively conservative treatment requires reduction and change of therapeutical approach to avoid functional limitations resulting from axial malpositioning. The sincere contact of bone fragments, accompanied by sufficient anatomical axial and conservative reduction techniques that maintain parossal perfusion as well as a limited osteosynthesis plate contact should be the aim of the operative strategy. The use of a new titanium osteosynthesis plate system with multi-point contact between bone and plate promotes the incorporation of vessels and callus formation at the bone-plate interface and leads to the realization of the aforementioned aim, which was revealed in animal studies before. In order to examine the results, 18 patients with forearm fractures were studied, which underwent reduction and internal fixation using this new titanium osteosynthesis plate, the multi-point contact plate (MPC) system. In these patients, functional and radiological results after plate removal were studied. Our initial clinical experiences with the MPC-plate for internal fixation confirm the animal study results. The in-growth of parossal vessels into the multiple inter-point spaces enhances the subimplant (bio-logical) formation of callus, which can be visualized radiographically and intraoperatively after plate removal. These results indicate that the MPC plate has marked advantages over conventional plates.

Adult↗

PubMed1997

Characterization of three distinct extradiol dioxygenases involved in mineralization of dibenzofuran by Terrabacter sp. strain DPO360.

The dibenzofuran-degrading bacterial strain DPO360 represents a new species of the genus Terrabacter together with the previously described dibenzofuran-mineralizing bacterial strain DPO1361 (K.-H. Engesser, V. Strubel, K. Christoglou, P. Fischer, and H. G. Rast, FEMS Microbiol. Lett. 65:205-210, 1989; V. Strubel, Ph.D. thesis, University of Stuttgart, Stuttgart, Germany, 1991; V. Strubel, H. G. Rast, W. Fietz, H.-J. Knackmuss, and K.-H. Engesser, FEMS Microbiol. Lett. 58:233-238, 1989). Two 2,3-dihydroxybiphenyl-1,2-dioxygenases (BphC1 and BphC2) and one catechol-2,3-dioxygenase (C23O) were shown to be expressed in Terrabacter sp. strain DPO360 growing with dibenzofuran as a sole source of carbon and energy. These enzymes exhibited strong sensitivity to oxygen. They were purified to apparent homogeneity as homodimers (BphC and BphC2) and as a homotetrameric catechol-2,3-dioxygenase (C23O). According to their specificity constants kcat/Km, both BphC1 and BphC2 were shown to be responsible for the cleavage of 2,2',3-trihydroxybiphenyl, the first metabolite in dibenzofuran mineralization along the angular dioxygenation pathway. With this substrate, BphC2 exhibited a considerably higher kcat/Km, value (183 microM/min) than BphC1 (29 microM/min). Catechol-2,3-dioxygenase was recognized to be not involved in the ring cleavage of 2,2',3-trihydroxybiphenyl (kcat/Km, 1 microM/min). Analysis of deduced amino acid sequence data of bphC1 revealed 36% sequence identity to nahC from Pseudomonas putida PpG7 (S. Harayama and M. Rekik, J. Biol. Chem. 264:15328-15333, 1989) and about 40% sequence identity to various bphC genes from different Pseudomonas and Rhodococcus strains. In addition, another 2,3-dihydroxybiphenyl-1,2-dioxygenase gene (bphC3) was cloned from the genome of Terrabacter sp. strain DPO360. Expression of this gene, however, could not be detected in Terrabacter sp. strain DPO360 after growth with dibenzofuran.

Amino Acid Sequence↗

PubMed1997

Insulin-like growth factor I in the teleost Oreochromis mossambicus, the tilapia: gene sequence, tissue expression, and cellular localization.

Using reverse transcription-PCR and molecular cloning, the complementary DNA sequence encoding preproinsulin-like growth factor I (IGF-I) of a teleost, the tilapia (Oreochromis mossambicus) was established from liver. At the amino acid level, tilapia IGF-I shows all residues necessary for the maintenance of tertiary structure and shares about 80% identity with IGF-I from other teleosts. The B and A domains of tilapia IGF-I show more than 90% homology to those of other teleosts and 86-93% to those of human. However, in contrast to salmonids, the C domain of tilapia is truncated. Reverse transcription-PCR analysis followed by Southern blotting with an internal probe specific for tilapia IGF-I indicated a transcript in liver, pancreas, gut, kidney, head kidney, gill, ovary, testis, eye, and brain. In correlation, parenchymal cells were identified as likely local production sites by the use of immunohistochemistry. IGF-I immunoreactivity was confined to D cells in pancreatic islets, gastroentero-endocrine cells, cells of renal proximal tubules, interrenal cells of the head kidney, gill chondrocytes, chloride cells of the gill epithelium, granulosa cells in the ovary, spermatocytes and Sertoli cells in testis, and neurons in retina and brain. The local production of IGF-I in multiple organs of the tilapia indicates paracrine/autocrine actions of IGF-I involved in organ-specific functions. The results further demonstrate that the primary structure of IGF-I, especially in the B and A domains, is highly conserved during phylogeny.

Amino Acid Sequence↗

PubMed1997

Brightness discrimination ability in the West Indian manatee (Trichechus manatus).

Two manatees were tested on their ability to discriminate brightness using a series of 30 shades of grey varying from white to black. The animals were trained to discriminate between different shades of grey in a twofold simultaneous-choice situation. Their ability to discern brightness differences correlates with Werber's law, and the calculated Werber fraction is 0.35.

Animals↗

PubMed1997

[Gastrectomy with radical D2 lymph node excision--effective and economically standardized therapy of adenocarcinoma of the stomach].

In a retrospective single center study, the impact of radical D2-lymph adenectomy and splenectomy on operativ course, morbidity, mortality and long-term survival, in 243 patients who underwent radical surgical therapy for gastric cancer, was analyzed. D2-lymph node dissection during gastrectomy or gastric resection did not influence blood loss, artificial respiration time, ICU days or surgical morbidity, whereas splenectomy correlated with a higher hospital mortality, leakage and abscess rate. Due to routinely performed D2-lymphadenectomy long term survival rate (5 years) was 40.6% for all (in detail: 96% in stage IA; 68.5%/IB; 61.2%/II; 35.8%/IIIA; 17.3%IIIB; and 2.6% in stage IV and 58.1% for curative resected patients.

Adenocarcinoma↗

PubMed1996

Depletion of intracellular calcium stores activates a calcium conducting nonselective cation current in mouse pancreatic acinar cells.

Receptor-mediated Ca2+ release from inositol (1,4,5)-trisphosphate (IP3)-sensitive Ca2+ stores causes "capacitative calcium entry" in many cell types (Putney, J. W., Jr. (1986) Cell Calcium 7, 1-12; Putney, J. W., Jr. (1990) Cell Calcium 11, 611-624). We used patch-clamp and fluorescence techniques in isolated mouse pancreatic acinar cells to identify ion currents and cytosolic calcium concentrations under conditions in which intracellular Ca2+ stores were emptied. We found that depletion of Ca2+ stores activated a calcium-release-activated nonselective cation current (ICRANC) which did not discriminate between monovalent cations. ICRANC possessed a significant conductance for Ca2+ and Ba2+. It was not inhibited by La3+, Gd3+, Co2+, or Cd2+ but was completely abolished by flufenamic acid or genistein. In whole cell and cell-attached recordings, a 40-45 pS nonselective cation channel was identified which was activated by Ca2+ store depletion. Calcium entry as detected by single cell fluorescence measurements with fluo-3 or fura-2, showed the same pharmacological properties as ICRANC. We conclude that in mouse pancreatic acinar cells 40-45 pS nonselective cation channels serve as a pathway for capacitative Ca2+ entry. This entry pathway differs from the previously described ICRAC (Hoth, M., and Penner, R. (1992) Nature 355, 353-356) in its ion-selectivity, pharmacological profile, and single-channel conductance.

Acetylcholine↗

PubMed1996

[Therapy of venous stenosis using wall stents].

OBJECTIVE: To evaluate the patency of Wallstents implanted for the treatment of venous stenoses in patients with benign or malignant disease. PATIENTS AND METHODS: 22 Wallstents (20 central venous; two peripheral) were implanted during a period of two years in 12 patients (nine men, three women; mean age 57.8 [26-76] years) with malignant venous stenoses (n = 9) or stenosed dialysis shunts (n = 3). Stent diameter ranged from 8-16 mm, length from 32-91 mm. Introduction of the stents were by percutaneous transfemoral catheterisation, in six patients with simultaneous wire placement from a cubital to the femoral vein. The superior vena cava was the involved vessel in six patients (in two each also the subclavian or brachiocephalic veins), in three only the subclavian vein, twice only the inferior vena cava and once the cephalic vein. RESULTS: The patency of the stents was checked after 4.7 +/- 3.6 (1-14) months, in seven patients clinically, by digital subtraction phlebography in three, by computed tomography in two. In nine patients there was no evidence of obstruction to flow or flow was normal. Stent occlusion had occurred in three patients, 4, 9 and 14 months after placement. There were no complications. Five patients died after a mean period of 4.8 +/- 3.6 (1-6.5) months from the underlying disease, without symptoms of obstruction to flow. CONCLUSION: Stent placement should be considered early, as it is a well-tolerated and effective palliative procedure for central venous stenoses associated with malignant disease or stenosis of dialysis shunts.

Adult↗