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Biomedical subjects

R Bender

Publications and source records attributed to R Bender.

At least 91 records · Page 5Linked to original sources
PubMed1991

Biochemical and behavioral characterization of a novel cholinergic agonist, SR 95639.

Selective M1 cholinergic agonists may be useful in treating dementias due to cholinergic hypofunction. SR 95639 has recently been described as such a compound. We found the compound to have affinity for M1 sites (Ki = 2.1 microM) which was approximately 3-fold higher than its affinity for M2 sites. Functional partial agonism was suggested by an inconsistent increase in phosphoinositide (PI) turnover in rat hippocampal slices, combined with blockade of carbachol-stimulated PI turnover. In vivo M2-mediated effects were absent. Scopolamine-induced hyperactivity was attenuated by SR 95639 and scopolamine-impaired inhibitory avoidance and radial maze performance were improved. The compound appears to be a weakly selective M1 partial agonist with potential advantages over existing compounds.

Animals↗
PubMed1991

Identification of EEG patterns occurring in anesthesia by means of autoregressive parameters.

In EEG analysis an automatic pattern recognition is of interest. In this paper the usefulness of autoregressive parameters to classify EEG segments recorded during anesthesia is examined. Assuming that the AR parameters are multivariate normally distributed, parametric methods of discriminant analysis can be applied. The results show that AR parameters have high discriminating power and that the lowest error classification rate (smaller than 3%) is obtained by using quadratic discriminant functions. Consequently autoregressive parameters are efficient for classifying EEG segments into general stages of anesthesia.

Adult↗
PubMed1988

Noninvasive Doppler color flow mapping for detection of anomalous origin of the left coronary artery from the pulmonary artery and for evaluation of surgical repair.

Anomalous origin of the left coronary artery from the pulmonary artery is a rare but important cause of congestive heart failure in infancy and of sudden death at all ages. Diagnosis is often missed when based solely on physical examination and noninvasive methods. A 4 year old patient is presented in whom mitral regurgitation was noted by a referring physician and an anomalous left coronary artery was found by Doppler color flow mapping upon referral and verified at cardiac catheterization. Doppler color flow mapping was also used intraoperatively using a gas-sterilized transducer to further clarify the hemodynamics and assess the surgical result. After creation of an intrapulmonary artery tunnel from the ostium of the left coronary artery to the aorta, anterograde coronary artery flow and absence of a residual left to right pulmonary artery shunt were verified during surgery by Doppler flow mapping. Postoperatively, residual mitral regurgitation and patency of the left coronary artery graft have been followed up serially by Doppler flow mapping. Therefore, Doppler color flow mapping is useful in the diagnosis and intraoperative and postoperative management of this important and potentially life-threatening abnormality.

Blood Vessel Prosthesis↗
PubMed1988

A general regression procedure for method transformation. Application of linear regression procedures for method comparison studies in clinical chemistry, Part III.

The biometrical treatment of laboratory data may require the estimation of a regression line for the transformation of one set of measurements to another. The regression procedure introduced in part I (1) of our work does not always yield unbiased results in such situations, since its estimators are not scale invariant. In part III we present the parameter estimation of a general regression equation which is scale invariant and retains all properties of the method comparison procedure, in particular its robustness. Its application is demonstrated by several examples, and the results are compared with other robust biometrical procedures. The mathematical aspects are explained in the appendix.

Biometry↗
PubMed1986

Altered light/dark activity difference with aging in two rat strains.

The daily activity rhythm of adult and senescent male rats of two different strains (Iva:SDIV and Emd:Wi-AF/Han) was evaluated over several days with a capacitance-induction motility monitor. The Iva:SDIV rats were 6 to 9 or 29 to 32 months old and the Emd:Wi-AF/Han rats were 3 to 5, 16 to 18, or 31 to 39 months old at the time of testing. The rats were maintained in individual cages under a 12:12 hr light/dark regimen prior to and during this experiment. Senescent rats were much less active during the dark phase and somewhat more active during the light phase than same-strain young adult rats. This pattern of results was found for measurement of gross and fine movements combined (high sensitivity setting) and to a lesser extent for gross movements alone (low sensitivity setting). Furthermore, in the senescent rats the absolute magnitude of the light/dark activity difference was found to be positively related to the subsequent survival time.

Aging↗
PubMed1986

Avoidance acquisition in adult and senescent rats.

Male rats aged 6, 19, or 33 months were trained successively in one- and two-way avoidance tasks. The one-way avoidance test consisted of up to 30 trials given in a single session with the conditional stimulus (CS; 14-kHz tone) presented for either 3 s or for 10 s in separate groups. Senescent rats performed poorest, middle-aged rats intermediately, and young adult rats best. Failure of the longer CS to yield better acquisition than the short CS in the senescent group suggested that the age-related deficit probably did not result from slower responding. In subsequent shuttle box training there was no appreciable age difference in achieving the learning criterion. A compound visual-auditory CS was used, and in further evaluation of well-trained rats it was found that the auditory component was much more effective than the visual component in eliciting avoidance. However, this differential effect of the two stimuli was much weaker in the senescent group than in the young adult group. Nonetheless, these same senescent and adult rats readily learned to make avoidance responses using only the auditory CS, demonstrating that this was an effective stimulus for all age groups.

Aging↗
PubMed1986

Piretanide in the treatment of essential hypertension. A double-blind comparison versus placebo.

In a randomized, double-blind parallel group study the 24-hour hypotensive effect of piretanide and its influence on biochemical variables were compared with those of placebo in patients with mild to moderate essential hypertension. Sixty patients entered the study, all of whom met the inclusion criteria (RRdiast between 95 and 120 mmHg). There was no drop-out during the study, so that the results of all 60 patients were statistically analysed. Piretanide produced a significant reduction of both systolic and diastolic blood pressure over 24 hours which was evident at four weeks and was maintained and further enhanced over the ensuing trial period. A mean maximal fall (at 12 weeks) of 10.7% (BPdiast supine) was observed. Placebo tablets did not produce any clinically relevant changes in systolic blood pressure, whereas a slight decrease was seen in diastolic blood pressure. This blood pressure reduction was significantly less in the placebo group than in the piretanide group at the end of the study (weeks 10 and 12). Dose doubling was needed in 13 of the 30 patients in the piretanide group, whereas as many as 20 out of 30 patients needed dose doubling in the placebo group. Pulse rate did not change relevantly during the trial in either group. A slight reduction in body weight was observed in the piretanide group. The mean values of serum potassium and sodium showed a slight decrease but remained within the normal range during the study period. A small increase in serum phosphorus was noted. None of these changes required any specific measures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Tendamistat (HOE 467), a tight-binding alpha-amylase inhibitor from Streptomyces tendae 4158. Isolation, biochemical properties.

Culture fluids of Streptomyces tendae 4158 (ATCC 31210) contain a new kind of polypeptide alpha-amylase inhibitor, tendamistat (HOE 467). Several methods of isolating this inhibitor are described, including two rapid crystallisation methods, which produce homogeneous material. A characteristic of tendamistat is its tight-binding, pH-independent inhibition kinetics and the specific inhibition of the mammalian alpha-amylase form a stoichiometric 1:1 complex, which cannot be separated into its individual components by sodium dodecyl sulphate or molecular sieve chromatography. Studies of the mode of action reveal that the alpha-amylase-inhibiting activity is linked to the intact disulphide bridges of the inhibitor. It is assumed that the multipoint protein-protein bond exists between the enzyme and tendamistat. It is shown that extracellular tendamistat inhibits amylase formed by streptomyces. We therefore assume a regulatory function in the microorganism. By-products of tendamistat, which possess similar enzyme-inhibiting properties, are also described.

Binding Sites↗
PubMed1984

Continuous-flow determination of an alpha-amylase inactivator in fermentation samples using a ferricyanide reagent.

A continuous-flow system has been developed in which pancreatic alpha-amylase is incubated with soluble starch at 37 degrees C. Reducing sugars being delivered at the "steady-state" hydrolysis of starch are dialyzed into a solution of alkaline ferricyanide. Ferricyanide is then reduced at 95 degrees C. The decrease in the absorbance of ferricyanide solution is recorded as "enzyme baseline." When samples containing alpha-amylase inactivator are introduced into the system, hydrolysis of starch is reduced according to the concentration of enzyme inactivator. The amount of inactivator in the samples is deduced from a standard curve of six standard concentrations using the Technicon Autoanalyzer II system manager in connection with a calculator for automated interpolation. This method allows to determine 40 samples/h with high sensitivity and precision (mean = 1.53 mg/liter; C.V. = 1.4%).

Animals↗
PubMed1984

The impact of discharge planning on chronic schizophrenic patients.

The authors studied the discharge planning process at four inpatient facilities and its impact on 119 chronic schizophrenic patients over a one-year period. Adequacy of discharge planning varied significantly among the inpatient units; the authors attributed this variance to communication between inpatient and outpatient staff, staff-patient ratios, and staff effort. Overall, staff were most thorough in planning drug treatment and aftercare and least thorough in planning living arrangements in the community. The authors found that adequacy of discharge planning for aftercare treatment as well as patients' economic situations significantly influenced both treatment compliance at three-month follow-up and rates of early rehospitalization.

Adolescent↗
PubMed1981

Automated synthesis of gene fragments.

The DNA/RNA Synthesizer provides a complete and automated procedure for the synthesis of DNA sequences. Each base unit is added in a 30-minute cycle, permitting a tetradecamer to be constructed in 6 1/2 hours. The complete procedure is described, including a practical procedure for isolation and purification of the desired DNA sequence.

Automation↗
PubMed1979

Pharmacokinetics of single and multiple doses of clobazam in humans.

1. The pharmacokinetics of clobazam and its biotransformation product N-desmethylclobazam were investigated after single and multiple doses in normal subjects. 2. The relevant physicochemical properties of clobazam were measured and are presented. Different assay methods (radiochemical, fluorimetric and gas chromatographic) were applied and the results correlated. 3. After single doses the pharmacokinetic profile of clobazam includes time to peak levels 1--4 h after dosing, peak levels increasing linearly with the logarithm of dose, and terminal half-lives of about 18 hours. At least 87% of an oral dose is absorbed, as indicated by urinary recovery of labelled material. 4. In multiple-dose studies unchanged clobazam levelled off at minimum steady-state concentrations within one week of dosing. During 28 d of medication N-desmethylclobazam accumulated to near steady-state levels about eight times higher than those of the unchanged compound. 5. No pharmacokinetic interactions were discovered between clobazam and the antidepressant nomifensine.

Anti-Anxiety Agents↗