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Biomedical subjects

A Schubert

Publications and source records attributed to A Schubert.

At least 19 recordsLinked to original sources

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

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

[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

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

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

(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

[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

The effect of ketamine on human somatosensory evoked potentials and its modification by nitrous oxide.

The effect of ketamine alone and in combination with N2O (70% inspired) on median nerve somatosensory evoked potentials (SSEPs) was investigated in 16 neurologically normal patients undergoing elective abdominopelvic procedures. The anesthetic regimen consisted of ketamine (2 mg/kg iv bolus followed by continuous infusion at a rate of 30 micrograms.kg-1.min-1) [corrected], neuromuscular blockade (atracurium), and mechanical ventilation with 100% oxygen. SSEP recordings were obtained immediately preinduction and at 2, 5, 10, 15, 20, and 30 min postinduction. Thereafter, N2O was added with surgical incision and maintained for 15 min. At 5-min intervals, SSEP recordings were again taken during and after N2O. With minor exceptions, mean cortical and noncortical latencies as well as noncortical-evoked potential amplitude were unaffected by either ketamine or N2O. Ketamine induction increased cortical amplitude significantly with maximal increases occurring within 2-10 min. For example, at 5-min postinduction, mean N1-P1 amplitude increased from 2.58 +/- 1.05 (baseline) to 2.98 +/- 1.20 microV and P1-N2 amplitude increased from 2.12 +/- 1.50 (baseline) to 3.99 +/- 1.76 microV. Throughout the 30-min period after ketamine induction, mean P1-N2 amplitude increased generally by more (57-88%) than did mean N1-P1 amplitude (6-16%). N2O added to the background ketamine anesthetic produced a rapid and consistent reduction in both N1-P1 and P1-N2 amplitude. Thus, at 1 min after N2O, mean N1-P1 amplitude decreased from 2.74 +/- 1.11 to 1.64 +/- 0.63 microV, while P1-N2 amplitude decreased from 3.32 +/- 1.52 to 1.84 +/- 0.87 microV.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult

pH-adjustment of 2-chloroprocaine quickens the onset of epidural anaesthesia.

The effect of pH-adjustment of three per cent 2-chloroprocaine (2-CP, Nesacaine MPF) on the onset, duration, and spread of epidural analgesia and anaesthesia was studied in patients undergoing lower extremity surgery. Forty ASA physical status I and II patients were randomized to two groups. In a double-blinded fashion, patients in both groups received an epidural injection of 15 ml of local anaesthetic (LA) solution via a Tuohy needle at the L3-4 interspace. Local anaesthesia for Group I was prepared by adding 3 mEq NaHCO3 to 27 ml three per cent 2-CP and for Group II was prepared by adding 3 ml 0.9 per cent NaCl to 27 ml three per cent 2-CP. Both solutions contained epinephrine (1:200,000). The pH of commercially prepared Nesacaine MPF was 3.19 +/- 0.02. The pH of the solutions used for Group I and Group II patients were 7.32 +/- 0.01 and 3.27 +/- 0.02, respectively. Times to analgesia and anaesthesia at the L2 dermatome were significantly decreased in Group I patients by 2.5 and 6.6 minutes, respectively. Likewise, pH-adjustment accelerated the attainment of maximum level of block by 2.8 min. No statistical differences were found between groups in the maximum level of epidural block, or in time to 2-segment regression. No precipitation of LA was observed in pH-adjusted solutions of 2-CP after 24 hours. We recommend the use of pH-adjusted three per cent 2-CP (Nesacaine MPF) to accelerate the onset of epidural block.

Adult

The effect of high-dose fentanyl on human median nerve somatosensory-evoked responses.

Median nerve somatosensory evoked responses (MnSSERs) were recorded in nine neurologically normal adult cardiac patients before and during the administration of high-dose fentanyl. MnSSERs were recorded prior to induction and at t = 20 min and t = 45 min postinduction. Fentanyl was administered as a slow bolus (53.2 +/- 9.1 micrograms X kg-1), followed by a continuous infusion at 10-20 micrograms X kg-1 X hr-1 (total dose 63.6 +/- 10.1 micrograms X kg-1). All MnSSER waveform components remained recordable and easily identifiable during anaesthesia. The effect of fentanyl was more pronounced on cortical waveform components, leaving subcortical components largely unaffected. There was a significant increase in the latency of the cortical MnSSER at t = 20 min, e.g., for the initial negative cortical wave, N1, the latency was 21.18 +/- 1.55 ms preinduction versus 22.18 +/- 1.42 ms at t = 20 min. There was also a significant decrease in the amplitude of the cortical response at t = 20 min, i.e., 2.04 +/- 1.30 microV preinduction versus 1.31 +/- 0.74 microV at t = 20 min. However, the degree of change was quite variable (range = 0-65 per cent). No further changes occurred at t = 45 min. The authors conclude that MnSSERs can be consistently and reliably monitored during high-dose fentanyl anaesthesia. However, fentanyl produces modest but significant changes in the MnSSER which should be taken into account lest they be misinterpreted as neurologic injury in evolution.

Aged

Loss of intraoperative evoked responses during dorsal column surgery associated with isolated postoperative sensory deficit.

Two patients underwent surgery for the removal of dermoid tumors that involved the dorsal aspect of the spinal cord. Both patients were monitored with intraoperative posterior tibial nerve somatosensory evoked potentials (SSEPs). In each case, the surgical procedure was nearly complete when an abrupt and persistent loss of SSEPs occurred. Although minor recovery of waveforms was present by the end of the operation, the SSEP waveforms remained strikingly abnormal. Neither patient had a postoperative motor deficit, although both had evidence of dorsal column dysfunction. These observations suggest that, during dorsal column surgery, even dramatic SSEP loss may not be associated with motor pathway injury, but rather, may correlate better with postoperative dorsal column dysfunction. The possible implications for intraoperative monitoring of SSEPs during dorsal column surgical procedures are discussed.

Child

The influence of stimulus presentation rate on the cortical amplitude and latency of intraoperative somatosensory-evoked potential recordings in patients with varying degrees of spinal cord injury.

Fourteen patients whose posterior tibial nerve somatosensory cortical-evoked potentials (SCEPs) were monitored for spinal surgery, underwent sequential recordings at different stimulus rates (6.1, 5.1, 4.1, 3.1, 2.1, and 1.1 Hz), after induction of anesthesia and patient positioning but before the incision was made. A markedly detrimental influence of higher (5.1 and 6.1 Hz), yet commonly used, stimulus rates on the amplitude of the evoked potential waveform was noticed. This tendency was most pronounced in patients with an antecedent spinal cord injury. In three patients with severe incomplete cord injuries, the amplitude of the cortical-evoked potential was sufficiently attenuated to preclude reliable intraoperative monitoring when stimulus rates of 5.1 Hz and greater were used. By contrast, evoked potentials could be monitored reliably in all patients when stimulus rates of 1.1 or 2.1 Hz were used. Six of seven patients (87%) whose evoked response amplitude showed a major reduction with higher stimulus frequencies had either a discrete sensory level or bilateral lower extremity weakness or both. Only two of seven patients (29%) whose evoked potential remained minimally affected by the stimulus rate had similar neurologic impairment. The authors conclude that, particularly in the setting of severe incomplete spinal cord injuries, the higher rates of stimulus presentation commonly used may result in failure to obtain waveforms that are adequate for intraoperative SCEP monitoring. The use of unconventionally low stimulus rates may greatly facilitate SCEP monitoring in such situations.

Adolescent

Effect of the acute administration of high dose pentobarbital on human brain stem auditory and median nerve somatosensory evoked responses.

Brain stem auditory (BAERs) and median nerve somatosensory evoked responses (MnSSERs) were recorded from normal neural pathways during the induction of pentobarbital coma in six patients undergoing elective excision of complex arteriovenous malformations. Each patient received a 33-minute infusion of pentobarbital at a rate of 0.6 mg/kg (total dose, 19.8 mg/kg). This regimen resulted in burst suppression or isoelectricity of the electroencephalogram in all patients. Although statistically significant changes in latency and amplitude occurred, both BAERs and MnSSERs were readily recordable in all patients throughout the infusion. For the BAER, there were significant increases in the latencies of Waves III and V. However, these increases are sufficiently small that misinterpretation of these changes as an evolving neurological injury is unlikely, e.g., Wave V latency increased from 6.25 +/- 0.25 (SD) to 6.58 +/- 0.16 ms (P less than 0.006). For the MnSSER, changes of greater potential clinical relevance were observed. There were substantial increases in the latencies of the early components of the primary cortical response and in the central conduction time (e.g., CCT of 6.1 +/- 0.6 ms preinduction vs. 7.7 +/- 1.1 ms at t = 33 min, P less than 0.003), and the amplitude of the early cortical response (N20-P25) decreased by a mean of 45% (P less than 0.02). By contrast, subcortical components of the MnSSER (brachial plexus, upper cervical spine) were only minimally affected. We conclude that, in patients who are initially neurologically intact, BAERs and MnSSERs can be monitored effectively during pentobarbital coma and that the loss of these responses should not be ascribed to the effects of this drug alone. However, the interpretation of evoked response changes, particularly MnSSER changes, that occur during pentobarbital administration should take into account the dose-related changes in latency and amplitude that we have observed.

Adult

Selenium content of a core group of foods based on a critical evaluation of published analytical data.

References published since 1960 that report analyses of selenium in foods were collected and evaluated according to criteria in five categories: number of samples, analytical method, sample handling, sampling plan, and analytical quality control. Data were grouped by food item and rated according to the criteria that had been developed specifically for evaluating the quality of selenium data. Ratings assigned to the data from each study yielded a Quality Index, indicating which data would be included in the calculation of the mean selenium value for each food item. The Quality Indexes for acceptable studies were summed to determine a Confidence Code, intended to indicate the relative degree of confidence the user can have in each mean selenium value. The selection of selenium core foods was based on their selenium concentration and frequency of consumption. Foods were ranked by multiplying selenium concentration by the amount consumed by the 36,255 individuals who provided 3-day dietary intake data in the U.S. Department of Agriculture's 1977-78 Nationwide Food Consumption Survey. Mean, minimum, and maximum selenium values, Confidence Codes, ranks, and references have been compiled for 114 food items. The five most highly ranked food aggregates (beef, white bread, pork, chicken, and eggs) provided half of the selenium accounted for in the diets of the survey respondents.

Diet

[Life expectancy of diabetics].

The disease-specific life expectancy of diabetics is significant for the organisation of medical care. The investigations show that the disease-specific expectation of life of diabetics from the beginning of the disease is considerably more insignificant in comparison to the further life expectancy of the population in the younger and middle age groups. Only with increasing age of onset the life expectations of diabetics draw towards those of the population. Thus the lower life expectancy of the diabetics of younger age groups from the beginning of the disease now as ever may point to a higher risk in comparison to the disease population at the decline of life.

Aged

The effect of acute hypocapnia on human median nerve somatosensory evoked responses.

This study was undertaken to define the effect of acute hypocapnia on intraoperatively recorded somatosensory evoked potentials (SSEPs). Median nerve SSEPs were studied in ten anesthetized neurologically normal adult patients undergoing elective nonneurologic surgery. End-tidal carbon dioxide tension (ETCO2) was allowed to stabilize for 15 min before SSEP recordings were obtained during normocapnia (N) (ETCO2 = 39.9 +/- 1.45 mm Hg), hypocapnia (H) (ETCO2 = 20.6 +/- 1.07 mm Hg), and after return to normocapnia (NR). Although a trend toward a reduction in the latencies of all SSEP components was evident, only the cervical (CII), and cortical (N1 and P1) latencies decreased significantly with H when compared to N. Mean latencies for CII, N1, and P1 (+/- SD) were, respectively, 14.80 +/- 1.14, 20.93 +/- 1.50, and 25.17 +/- 2.88 msec during N, and 14.50 +/- 1.13, 20.25 +/- 1.49, and 24.23 +/- 2.52 msec during H. On return to normocapnia, latencies were unchanged from N. Cortical latencies were affected to a greater extent than subcortical ones. Aside from a small but statistically significant increase in CII amplitude at H (2.05 +/- 0.55 microV vs 1.83 +/- 0.49 microV at N), SSEP amplitudes were unaffected by hypocapnia. The authors conclude that acute hypocapnia in neurologically normal patients results in a small reduction of SSEP latencies. The magnitude of the change is such that it is unlikely to interfere with recording or interpretation of intraoperative SSEPs.

Carbon Dioxide