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Biomedical subjects

A Schubert

Publications and source records attributed to A Schubert.

At least 73 records · Page 4Linked to original sources
PubMed1994

The effect of propofol on the electroencephalogram of patients with epilepsy.

The effect of propofol on the electroencephalogram (EEG) in patients with epilepsy is still unclear. Case reports with electroencephalographic documentation highlight pro- and anticonvulsant effects and beta activation of the EEG. This prospective study sought to determine the effect of propofol in 17 patients undergoing cortical resection for intractable epilepsy. Each patient received 2 mg/kg of propofol intravenously and the EEG was recorded from chronically implanted subdural electrodes placed during a previous craniotomy. Frequency of interictal spikes, time to burst suppression, and appearance of beta activation were recorded. The median frequency of interictal spikes decreased significantly from 2 spikes/min before to 0 spikes/min after propofol (P = 0.001). Seizure activity did not increase after propofol. Profound burst suppression and an increase in beta activity were noted consistently. The use of propofol in patients with epilepsy seems to be safe but may interfere with the recording of EEG spikes.

Adolescent↗
PubMed1994

Contrasting effects of vecuronium and succinylcholine on the renal microcirculation in rodents.

We assessed the effects of succinylcholine and vecuronium on renal function and on the renal microcirculation in a rodent model. Vecuronium (0.02 mg/kg followed by 0.2 mg.kg-1 x h-1) caused a significant decrease of 16.1% +/- 3.87% in inulin clearance from 0.92 +/- 0.07 to 0.71 +/- 0.05 mL.min-1 x gKW-1 (gram of kidney weight), and a decrease in para-aminohippuric acid clearance by 21.6% +/- 4.69% from 1.58 +/- 0.26 to 1.31 +/- 0.20 mL.min-1 x gKW-1 (P < 0.05), whereas succinylcholine (0.45 mg/kg followed by 2 mg.kg-1 x h-1) altered neither. The effect of these muscle relaxants was also determined on the renal microcirculation in separate experiments using videomicroscopy. Succinylcholine (n = 10; 10(-10) to 10(-6) M) and its parent compound, acetylcholine (n = 10, 10(-10) to 10(-6) M) used as a control, caused a significant vasodilation from baseline diameter in the interlobular, afferent, and efferent arterioles. The vasodilation caused by succinylcholine was significantly less than that observed with acetylcholine. Atropine blocked the response to succinylcholine, indicating the latter has a muscarinic effect. In contrast, vecuronium caused a significant, selective vasoconstriction from baseline diameter in the preglomerular vessels, but not in the postglomerular vessels. The vasoconstriction caused by vecuronium was significantly different than the vasodilation caused by succinylcholine. The preglomerular vasoconstriction observed with vecuronium may contribute to the decrease in renal plasma flow and glomerular filtration rate observed experimentally. The choice of a neuromuscular blocking drug can therefore have the potential to influence renal function by altering the renal microcirculation.

Animals↗
PubMed1993

Role of Helicobacter pylori serology in evaluating treatment success.

Duodenal ulcer recurrence and gastritis are reduced with successful Helicobacter pylori treatment. Serology is accurate in the diagnosis of H. pylori, but its value in determining eradication is unproved. To evaluate the usefulness of serology in monitoring treatment, we measured serial serum antibodies in three patient groups: eradication success (N = 57), eradication failure (N = 19), and untreated patients (N = 24). Eradication was determined by Warthin Starry staining of antral biopsies and repeat 13C breath tests at six weeks. Subsequent 13C breath tests were then performed at three-month intervals to monitor eradication. IgG antibody concentrations to H. pylori were determined by a commercially available ELISA kit. Serology concentrations remained constant throughout the study period in the untreated patients. IgG concentrations decreased slightly in the treatment failure group at six weeks but thereafter remained at baseline values. In the eradicated group, serum IgG concentrations decreased 26% by three months, 43% by six months and 55% at nine and 12 months (P < 0.001). A 20% reduction in IgG concentrations by six months was associated with successful treatment (sensitivity 86% and specificity 88%). We conclude that serology is a potentially useful way to monitor H. pylori treatment success.

Adult↗
PubMed1993

Endotracheal tube obstruction during stereotactic craniotomy.

The authors present a case of endotracheal tube (ETT) obstruction during stereotactic computer-assisted volumetric resection of an enlarging left thalamic mass in a prone patient. The head was fixed in a stereotactic COMPASS head frame and the patient positioned on transverse hip and shoulder rolls. The prone position was achieved with attention given to ensure an adequate distance between the sternum and mentum. At the time of dural incision, the patient's peak airway pressure and end-tidal CO2 tension increased markedly whereas the O2 saturation remained stable at 99%. It immediately became clear that the patient's torso had moved cephalad resulting in ETT obstruction, despite the continued integrity of head fixation. We emphasize the need for proper and safe patient positioning, the placement of a bite block between the molar teeth, and particularly in obese patients, the need to tape the patient's torso securely to the operating room table. In addition, it may be necessary to place the operating room table in reverse Trendelenberg position to prevent cephalad movement of the torso. This case represents an unusual mechanism of ETT obstruction, as normally the latter is caused by flexion of the head rather than by cephalad movement of the torso.

Adult↗
PubMed1993

Intravenous sedation for MR imaging of the brain and spine in children: pentobarbital versus propofol.

The authors present a prospective study of single-agent pediatric sedation regimens for patients older than 2 years of age undergoing magnetic resonance (MR) imaging of the brain and spine. Thirty patients underwent MR imaging after intravenous administration of pentobarbital in successive boluses of 2.5 mg/kg to a maximum of 7.5 mg/kg. Thirty-one patients received an intravenous bolus followed by continuous infusion of propofol. The dosage schedule for propofol was 2 mg/kg (with supplemental 1 mg/kg boluses) followed by continuous infusion of 6 mg/kg per hour. There was no significant difference in the physiologic response to sedation between the two groups, although the magnitude of the drop in pulse was significantly greater in the group receiving propofol. Three patients receiving propofol experienced transient decreases in oxygen saturation, at variable times over the course of the procedure. However, patients recovered significantly faster from sedation with propofol. While propofol may represent a viable alternative to pentobarbital in selected patients, propofol requires constant physician supervision and meticulous technique.

Brain↗
PubMed1992

Systemic lidocaine and human somatosensory-evoked potentials during sufentanil-isoflurane anaesthesia.

The effect of systemically administered lidocaine on somatosensory evoked potentials (SSEPs) during general anaesthesia has not been widely reported. Knowledge of the influence of anaesthetic agents on evoked potentials assists in interpreting evoked potential waveforms. Accordingly, we studied the behaviour of cortical and subcortical (recorded at the second cervical vertebra) SSEPs after administration of intravenous lidocaine (3 mg.kg-1 bolus followed by infusion at 4 mg.kg-1.hr-1) during a sufentanil-based anaesthetic regimen in 16 patients undergoing abdominal or orthopaedic surgery. When compared to awake baseline recordings, the sufentanil-nitrous oxide, low-dose isoflurane anaesthetic depressed N1 amplitude by approximately 40% and prolonged latency by 10%. Fifteen minutes after establishment of this anaesthetic, the amplitude and latency of N1 were 1.13 +/- 0.56 microV and 19.81 +/- 1.63 msec, respectively. Within five minutes of adding lidocaine, amplitude decreased further to 0.84 +/- 0.39 microV (P = 0.001), while latency was extended to 20.44 +/- 1.48 msec (P = 0.01). Lidocaine did not affect cervical amplitude and prolonged latency only minimally. Despite the observed effects on amplitude and latency, SSEP waveforms were preserved and interpretable. Plasma lidocaine levels obtained at 5, 20, and 40 minutes after lidocaine were 5.17 +/- 1.33, 3.76 +/- 1.14, and 3.66 +/- 0.9 micrograms.dl-1, respectively. Our results indicate that systemically administered lidocaine at therapeutic plasma levels acts synergistically with a sufentanil-based anaesthetic to depress the amplitude and prolong the latency of SSEPs.

Adult↗
PubMed1992

Determination of S fimbriae among Escherichia coli strains from extraintestinal infections by colony hybridization and dot enzyme immunoassay.

449 E. coli strains obtained from septic infections (124 isolates), urinary tract infections (246) and water (79) were surveyed for S/F1C fimbrial DNA by DNA hybridization and for expression of S fimbriae by enzyme immunoassay. S/F1C fimbrial DNA was detected with greater frequency in septic (35%) and urinary (43%) isolates than in water isolates and was often associated with the O2, O4, O6, O18, O83, and O156 serogroups. Most O45 strains did not possess such sequences. Only 12% and 28%, respectively, of the septic and urinary strains possessing S/F1C fimbrial DNA expressed S fimbriae.

Bacteremia↗
PubMed1991

[WHO Special Program of Research, Development and Research Training in Human Reproduction (HRP). A summary].

The world population is still increasing dramatically. This rapid growth takes place mainly in developing countries and represents a considerable obstacle to the improvement of the economic and social conditions in these countries. A higher acceptance of various fertility-regulating methods is one important factor in the reduction of the population growth. An increasing acceptance cannot be realised without the general availability of safe and effective methods for all users while considering and respecting the multiple different cultural backgrounds. The WHO Special Programme of Research, Development and Research Training in Human Reproduction (HRP), a programme of an international organisation with high esteem particularly in developing countries, contributes considerably to this field, therefore should be supported more widely.

Contraception↗
PubMed1991

Intrathecal morphine does not reduce minimum alveolar concentration of halothane in humans: results of a double-blind study.

The effect of intrathecal morphine on the minimum alveolar concentration (MAC) of halothane was investigated in 22 patients undergoing elective abdominal surgery. The patients were randomly assigned to the control (CTRL) or intrathecal morphine sulfate (ITMS)-treated groups. Approximately 2.5 h before induction of anesthesia with halothane, the ITMS-treated group received 15 micrograms/kg preservative-free ITMS (Duramorph; Elkins-Sinn, Cherry Hill, NJ) while in the right lateral decubitus position. The CTRL group was treated in an identical fashion except that, after placement of the introducer needle, actual dural puncture was omitted. After inhalational induction with halothane as the sole anesthetic agent, the patients' responses to surgical incision were recorded. MAC was determined with the modified up-down method of Dixon and verified with probit analysis. MAC (+/- SE) after ITMS was 0.76 +/- 0.06, compared with a CTRL MAC of 0.78 +/- 0.15 (not significant). Under the conditions of this study, the MAC of halothane in humans was not significantly affected by ITMS.

Adult↗
PubMed1991

The effect of intrathecal morphine on somatosensory evoked potentials in awake humans.

Although the effect of systemic opioids on somatosensory evoked potentials has been well described, little is known about the interaction between intrathecally administered opioid analgesics and somatosensory evoked potentials. Accordingly, the influence of intrathecally administered morphine on posterior tibial nerve somatosensory cortical evoked potentials (PTSCEPs) was investigated in 22 unpremedicated, awake, neurologically normal patients scheduled to undergo elective abdominal or pelvic procedures. Patients were randomly assigned to receive either preservation-free intrathecal morphine sulfate (ITMS) or placebo. After baseline PTSCEP, heart rate and, mean blood pressure were recorded, ITMS (15 micrograms.kg-1) was injected via standard dural puncture with the patient in the lateral position. PTSCEPs, heart rate, and mean blood pressure were recorded again at 5, 10, 20, 30, 60, 90, and 120 min. Control patients were treated identically (including position, sterile preparation, and subcutaneous tissue infiltration with local anesthetic), except for lumbar puncture, and were unaware of their randomization. Before administration of ITMS, PTSCEP P1, N1, P2, N2, and P3 latencies were 39.4 +/- 3.2, 47.6 +/- 3.9, 59.2 +/- 3.2, 70.4 +/- 3.7, and 84.6 +/- 5.5 ms, (mean +/- standard deviation), respectively. The corresponding P1-N1, N1-P2, and P2-N2 amplitudes were 2.4 +/- 1.1, 2.4 +/- 1.1, and 2.3 +/- 0.9 microV, respectively. There were no significant changes over time between the control and ITMS groups. PTSCEPs resulting from left-sided stimulation were not different from those elicited by right-sided stimulation. All ITMS patients had intense postoperative analgesia for at least 24 h. It is concluded that ITMS does not affect PTSCEP waveforms in the 35-90 ms latency range during the awake state.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1991

(K15R M52E) aprotinin is a weak Kunitz-type inhibitor of HIV-1 replication in H9 cells.

The (K15R M52E) aprotinin is a recombinant molecule with a broader inhibition spectrum against serine proteinases and a higher affinity towards certain proteinases as compared to native aprotinin. This aprotinin variant was produced in E. coli, isolated and purified to homogeneity. The inhibitor was further tested for its effectiveness to reduce human immunodeficiency virus type 1 (HIV-1) replication. Virus growth was followed by an ELISA which detects the amount of virus core protein p24. At a concentration of 50 microM, the recombinant (K15R M52E) aprotinin clearly reduced HIV-1 replication in H9 cells.

Amino Acid Sequence↗
PubMed1991

[Lung cancer in a rural area of Mecklenburg-Vorpommern without air pollution].

Results of an epidemiological study of malignant neoplasms of the trachea, the bronchus and the lungs in a rural district of Mecklenburg-Vorpommern in North-Eastern Germany. The rate of disease in men and in women is determined by the proportion of age groups in the population in whom the probability of contracting the disease is highest. At first the incidence increased year by year, but now the rate of new cases seems to have levelled out and is now constant, i.e. approximately the same per annum. Despite constant or even increasing exposure e.g. to inhaled noxious substances via tobacco smoking, not all persons are equally susceptible. The levelling out of the incidence rate of cancer may be due to a genetically fixed susceptibility.

Adult↗