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Biomedical subjects

R Schmid

Publications and source records attributed to R Schmid.

449 records · Page 25Linked to original sources
PubMedDate not supplied

Association experiments with aerobic and anaerobic pathogens: a model of in-vitro susceptibility testing in mixed infections. Activity of enoxacin, clindamycin, and metronidazole.

In infections of polymicrobial etiology, it seems mandatory to combine an antibiotic with marginal activity against anaerobes with an anti-anaerobic drug, e.g. metronidazole or clindamycin. We investigated the effect of associations of anaerobic and facultatively anaerobic pathogens on MBCs of enoxacin, clindamycin, metronidazole, and combinations of enoxacin plus clindamycin or metronidazole. Single testing, and associations of Bacteroides fragilis with Escherichia coli or Enterococcus faecalis revealed MBCs of 64 mg/l for enoxacin. However, investigating metronidazole, MBCs for B. fragilis increased from 0.5-1 mg/l to 2-4 mg/l in association with E. coli. The combination of enoxacin with metronidazole restored MBCs of 0.5 and 1 mg/l for the B. fragilis strains. B. fragilis associated with E. faecalis showed MBCs of 2 to 64 mg/l for metronidazole, an increase of up to 64-fold. The enoxacin MBCs for E. coli in association with B. fragilis were up to eight-fold higher than for E. coli alone (2 mg/l compared to 0.25 mg/l). Association of E. coli with E. faecalis and B. fragilis showed a low to moderate increase for MBCs of E. coli when enoxacin was tested alone or in combination with metronidazole or clindamycin. In contrast, MBCs for E. faecalis did not change significantly with any of the associations or combinations tested. It is evident that in vitro antimicrobial susceptibility of associations of pathogens can be modified by interactions between strains, and/or antimicrobials.

Bacteria, Aerobic↗
PubMedDate not supplied

5-Hydroxy-indolacetic-acid (5-HIAA) serum levels in depressive patients and ECT.

In 31 drug and ECT naive melancholic patients, serum levels of the major metabolite of serotonin 5-hydroxy-indolacetic-acid (5-HIAA) were estimated in the first and third ECT of a course. Plasma samples were taken before ECT and 1, 60 and 120 min thereafter. The estimations were done by a new high performance liquid chromatography method (HPLC). After the seizure, a statistically significant decrease of 5-HIAA serum levels was observed over both ECTs. There was a significant increase in 5-HIAA serum levels from the first to the third ECT. ECT was found to influence serotonin turnover. It might be interpreted that ECT improves serotonergic responsiveness and neurotransmission. There was no significant correlation between 5-HIAA levels and gender, or age of the patients, or seizure duration. Furthermore, the severity of depression and treatment response did not correlate with certain 5-HIAA serum level patterns.

Adult↗
PubMedDate not supplied

Effect of vasoactive intestinal peptide, peptide histidine isoleucine and growth hormone-releasing factor-40 on bombesin-like immunoreactivity, somatostatin and gastrin release from the perfused rat stomach.

Bombesin-like immunoreactivity (BLI) has been demonstrated in neurons of the gastrointestinal tract and gastric BLI secretion can be demonstrated in response to the classical neurotransmitter acetylcholine. Since structurally related peptides VIP, PHI and GRF have to be considered as peptidergic neurotransmitters it was of interest to determine their effect on gastric BLI secretion. Additionally, somatostatin (SLI) and gastrin secretion was examined. The isolated stomach of overnight fasted rats was perfused with Krebs-Ringer buffer via the celiac artery and the effluent was collected via the portal vein. The gastric lumen was perfused with isotonic saline at pH7 or pH2. All four peptides were tested at a dose of 10(-11) M and 10(-8) M at both pH levels and in addition the effect of VIP and PHI was examined at 10(-14) M and 10(-12) M during luminal pH2. At luminal pH7 VIP and PHI stimulated SLI release at 10(-8) M but had no effect on BLI or gastrin secretion. rGRF and hpGRF were both ineffective on SLI and gastrin release while rGRF inhibited and hpGRF stimulated BLI secretion. This effect was not dose related. At luminal pH2 all four peptides stimulated BLI secretion. Stimulation by PHI was already observed at a dose of 10(-14) M while VIP elicited a stimulatory effect at 10(-12) M. PHI at the two lowest concentrations of 10(-14) and 10(-12) M elicited a stimulation of SLI and gastrin release while the same doses of VIP and the higher doses of all four peptides had no effect on SLI and gastrin secretion at an acidic intraluminal pH.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Piperidine renin inhibitors: from leads to drug candidates.

Non-peptidomimetic renin inhibitors of the piperidine type represent a novel structural class of compounds potentially free of the drawbacks seen with peptidomimetic compounds so far. Synthetic optimization in two structural series focusing on improvement of potency, as well as on physicochemical properties and metabolic stability, has led to the identification of two candidate compounds 14 and 23. Both display potent and long-lasting blood pressure lowering effects in conscious sodium-depleted marmoset monkeys and double transgenic rats harboring both the human angiotensinogen and the human renin genes. In addition, 14 normalizes albuminuria and kidney tissue damage in these rats when given over a period of 4 weeks. These data suggest that treatment of chronic renal failure patients with a renin inhibitor might result in a significant improvement of the disease status.

Animals↗
PubMedDate not supplied

Biochemical identification of a lipoprotein with maltose-binding activity in the thermoacidophilic Gram-positive bacterium Alicyclobacillus acidocaldarius.

Growth of the thermoacidophilic Gram-positive bacterium Alicyclobacillus acidocaldarius strain ATCC 27009 on maltose resulted in the increased production of a protein with apparent molecular mass of 40 kDa. By metabolic labelling with 14C-palmitic acid, the 40-kDa protein was identified as a lipoprotein. The protein exhibited maltose-binding activity at pH 3.5, as demonstrated by chromatography on cross-linked amylose. Partial amino acid sequence analysis revealed that the 40-kDa protein corresponds to the product of an open reading frame downstream from the amylase gene (amy) that displays similarity to enterobacterial maltose-binding proteins.

Amino Acid Sequence↗
PubMedDate not supplied

Bak expression and cell death occur in peritumorous tissue but not in pancreatic cancer cells.

Bak is a pro-apoptotic member of the Bcl-2 family whose genes are involved in regulation of programmed cell death. Using in situ hybridization, immunohistochemistry, and Northern blot analysis, we studied the expression of Bak in specimens from 12 normal pancreata and 26 primary pancreatic cancers, and correlated the findings with the clinical and histopathologic data of the patients. By comparison with normal pancreas, Northern blot analysis demonstrated a 2.5-fold increase of Bak messenger RNA expression in the tumor samples (P <0. 001). Elevated levels were found in 15 of the 26 pancreatic cancer tissue specimens. In these samples Bak expression was increased 4.3 fold (P <0.001). No association was detected between Bak expression and tumor stage. In situ hybridization and immunohistochemistry revealed that the tumor cells themselves and the stroma cells expressed only low levels of Bak. In contrast, in regions adjacent to the tumor, which showed chronic inflammation, there was always high expression in the acinar and inflammatory cells, explaining the increased Bak levels found in the tumor samples by means of Northern blot analysis. In the normal pancreas the expression of Bak was generally moderate in the acinar cells and low in the ductal and islet cells. In situ analysis using the terminal deoxynucleotidyl transferase method further showed that there was extensive cell death in the peritumorous areas with chronic inflammation. Taken together, these results suggest that in pancreatic cancer Bak expression and programmed cell death are present in cells that are localized in regions of chronic inflammation surrounding the pancreatic cancer cells but not in the tumor cells themselves, a situation that may facilitate tumor growth and spread.

Adolescent↗
PubMedDate not supplied

Modified technique for heterotopic rat heart transplantation under cardioplegic arrest.

The development of microsurgical techniques offers a valuable opportunity to use small animals for experimental studies of vascularized organ transplants. Availability of inbred strains, natural resistance to infection, and economy make the rat an ideal animal model to investigate the effects of heart transplantation. The recent high interest and substantial laboratory activity with regard to posttransplantory immunological tissue reactions and apoptotic tissue processes led us to optimize transplantation technique by improving myocardial protection during ischemia and thereby minimizing adverse effects of the transplantation procedure itself. Thus the present report details the technique of heterotopic heart transplantation in rats using cardioplegic arrest.

Anastomosis, Surgical↗
PubMedDate not supplied

Powdered milk micellar casein prevents oral colonization by Streptococcus sobrinus and dental caries in rats: a basis for the caries-protective effect of dairy products.

Three animal studies were performed to investigate the influence of the macromolecular structure of milk casein on caries incidence and the possible ecological changes of the oral microbiota by such casein fractions. Towards this end, rats were infected with mixed bacterial suspensions of Streptococcus sobrinus OMZ 176 and Actinomyces viscosus Ny1. Various milk protein fractions were incorporated into carefully balanced powdered cariogenic diets to constitute the sole major protein component. Diets containing micellar casein had a pronounced and highly significant effect on almost all clinical and microbiological parameters examined. Both the formation of advanced dentinal fissure (B) and smooth surface (E) caries lesions was inhibited by diets containing micellar casein; this caries-inhibiting effect appeared to be due mainly to modifications within the plaque microbiota. The proportion of S. sobrinus in the oral cavity of rats was reduced (73-80%) by micellar casein-containing preparations, whereas the A. viscosus population was increased. Both these microbiological parameters were always negatively correlated. This appears to be the first example of a food component other than dietary sugars, selectively modifying the composition of the dental plaque microbiota of rats in such a way as to reduce its pathogenic potential. It also demonstrates the importance of establishing a molecular basis for the role of food components, which prove to be beneficial to oral health.

Actinomyces viscosus↗
PubMedDate not supplied

Quantification of vestibular compensation in unilateral Meniere's disease.

The main parameters of the vestibulo-ocular reflex (i.e. the gain or reflectivity, the long-time constant of the semicircular canals, the time constant of the mechano-neural transduction, and that of the central leaky integrator) were computed from the post-rotational nystagmic responses of unilateral Meniere's patients. Comparison with normal subjects showed a decrease of the first two parameters both in CW and CCW responses. No significant changes were observed in the remaining parameters. Probably due to a process of central compensation, a high level of symmetry was observed mainly in longstanding patients.

Adult↗
PubMedDate not supplied

[Electrochemical reduction of cytochrome P450s based on electrodes with immobilized substrates].

A new approach for the electrochemical reduction of cytochromes P450 (P450s, CYPs) with electrodes chemically modified with appropriate substrates of P450s ("reverse" electrodes) has been proposed. The method is based on the analysis of cyclic voltammograms, square wave voltammograms, amperograms and determination of such electrochemical characteristics as catalytic current and redox potential. The sensitivity of the proposed method is 0.2-1 nmol P450/electrode. The differences of maximal current and potentials in square wave voltammograms and catalytic current in amperometric measurements are more sensitive and reliable. Planar regime of screen-printed electrodes permits to use 20-60 microl of electrolyte volume. We investigated P450 2B4--benzphetamine or P450scc--cholesterol enzyme - substrate pairs. Electrochemical parameters of electrodes with nonspecific P450 substrate were differed from electrodes with appropriate substrates.

Aryl Hydrocarbon Hydroxylases↗
PubMedDate not supplied

Eye-head coordination toward auditory and visual targets in humans.

Eye-head coordination during gaze orientation toward auditory targets in total darkness has been examined in human subjects. The findings have been compared, for the same subjects, with those obtained by using visual targets. The use of auditory targets when investigating eye-head coordination has some advantages with respect to the more common use of visual targets: (i) more eccentric target positions can be presented to the subject; (ii) visual feedback is excluded during the execution of gaze displacement; (iii) complex patterns of saccadic responses can be elicited. This last aspect is particularly interesting for examining the coupling between the eyes and the head displacements. The experimental findings indicate that during gaze orientation toward a visual or an auditory target the central nervous system adopts the same strategy of using both the saccadic mechanism and the head motor plant. In spite of a common strategy, qualitative and quantitative parameters of the resulting eye-head coordination are slightly different, depending on the nature of the target. The findings relating to patterns of eye-head coordination seem to indicate a dissociation between the eyes and the head, which receive different motor commands independently generated from the gaze error signal. The experimental findings reported in this paper have been summarized in a model of the gaze control system that makes use of a gaze feedback hypothesis through the central reconstruction of the eye and head positions.

Adult↗