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Biomedical subjects

A Schubert

Publications and source records attributed to A Schubert.

At least 37 records · Page 2Linked to original sources

Nodular regenerative hyperplasia of the liver: case report of a 13-year-old girl and review of the literature.

BACKGROUND: Nodular regenerative hyperplasia (NRH) of the liver is a multi-acinar regenerative nodular lesion in a non-cirrhotic liver. It is a rare entity, especially in children, and remains of unknown aetiology. OBJECTIVE: NRH is often seen in association with other diseases or drug intake. In half of patients it is complicated by portal hypertension. Radiologically, its nodular appearance may look like neoplasia. RESULTS: We report a case of NRH with enormous hepatomegaly and multiple huge nodules. CONCLUSION: We wish to emphasise the importance of open wedge biopsy to establish diagnosis, since the prognosis of NRH in the absence of portal hypertension is good. Complications such as rupture of a nodule are rare.

Adolescent↗

Fullerene data mining using bibliometrics and database tomography

Database tomography (DT) is a textual database analysis system consisting of two major components: (1) algorithms for extracting multiword phrase frequencies and phrase proximities (physical closeness of the multiword technical phrases) from any type of large textual database, to augment (2) interpretative capabilities of the expert human analyst. DT was used to derive technical intelligence from a fullerenes database derived from the Science Citation Index and the Engineering Compendex. Phrase frequency analysis by the technical domain experts provided the pervasive technical themes of the fullerenes database, and phrase proximity analysis provided the relationships among the pervasive technical themes. Bibliometric analysis of the fullerenes literature supplemented the DT results with author/journal/institution publication and citation data. Comparisons of fullerenes results with past analyses of similarly structured near-earth space, chemistry, hypersonic/supersonic flow, aircraft, and ship hydrodynamics databases are made. One important finding is that many of the normalized bibliometric distribution functions are extremely consistent across these diverse technical domains and could reasonably be expected to apply to broader chemical topics than fullerenes that span multiple structural classes. Finally, lessons learned about integrating the technical domain experts with the data mining tools are presented.

Journal Article↗

Relation between perioperative hypertension and intracranial hemorrhage after craniotomy.

BACKGROUND: Previous data suggest that systemic hypertension (HTN) is a risk factor for postcraniotomy intracranial hemorrhage (ICH). The authors examined the relation between perioperative blood pressure elevation and postoperative ICH using a retrospective case control design. METHODS: The hospital's database of all patients undergoing craniotomy from 1976 to 1992 was screened. Coagulopathic and unmatchable patients were excluded. There were 69 evaluable patients who developed ICH postoperatively (n = 69). A 2-to-1 matched (by age, date of surgery, pathologic diagnosis, surgical procedure, and surgeon) control group without postoperative ICH was assembled (n = 138). Preoperative, intraoperative, and postoperative blood pressure records (up to 12 h) were examined. Incidence of perioperative HTN (blood pressure > or = 160/90 mmHg) and odds ratios for ICH were determined. RESULTS: Of the 11,214 craniotomy patients, 86 (0.77%) suffered ICH, and 69 fulfilled inclusion criteria. The incidence of preoperative HTN was similar in the ICH (34%) and the control (24%) groups. ICH occurred 21 h (median) postoperatively, with an interquartile range of 4-52 h. Sixty-two percent of ICH patients had intraoperative HTN, compared with only 34% of controls (P < 0.001). Sixty-two percent of the ICH patients had prehemorrhage HTN in the initial 12 postoperative hours versus 25% of controls (P < 0.001), with an odds ratio of 4.6 (P < 0.001) for postoperative ICH. Hospital stay (median, 24.5 vs. 11.0 days), and mortality (18.2 vs. 1.6%) were significantly greater in the ICH than in the control groups. CONCLUSIONS: ICH after craniotomy is associated with severely prolonged hospital stay and mortality. Acute blood pressure elevations occur frequently prior to postcraniotomy ICH. Patients who develop postcraniotomy ICH are more likely to be hypertensive in the intraoperative and early postoperative periods.

Case-Control Studies↗

Adenine nucleotide translocase-1, a component of the permeability transition pore, can dominantly induce apoptosis.

Here, we describe the isolation of adenine nucleotide translocase-1 (ANT-1) in a screen for dominant, apoptosis-inducing genes. ANT-1 is a component of the mitochondrial permeability transition complex, a protein aggregate connecting the inner with the outer mitochondrial membrane that has recently been implicated in apoptosis. ANT-1 expression led to all features of apoptosis, such as phenotypic alterations, collapse of the mitochondrial membrane potential, cytochrome c release, caspase activation, and DNA degradation. Both point mutations that impair ANT-1 in its known activity to transport ADP and ATP as well as the NH(2)-terminal half of the protein could still induce apoptosis. Interestingly, ANT-2, a highly homologous protein could not lead to cell death, demonstrating the specificity of the signal for apoptosis induction. In contrast to Bax, a proapoptotic Bcl-2 gene, ANT-1 was unable to elicit a form of cell death in yeast. This and the observed repression of apoptosis by the ANT-1-interacting protein cyclophilin D suggest that the suicidal effect of ANT-1 is mediated by specific protein-protein interactions within the permeability transition pore.

Animals↗

A Bayesian hierarchical model for multi-level repeated ordinal data: analysis of oral practice examinations in a large anaesthesiology training programme.

Oral practice examinations (OPEs) are used in many anaesthesiology programmes to familiarize anaesthesiology residents with the format of the oral examination administered by the American Board of Anesthesiology. The OPE outcome (final grade) consists of 'Definite Not Pass', 'Probable Not Pass', 'Probable Pass' and 'Definite Pass'. In our study to assess the validity of the OPE, residents took an average of two (ranging from one to six) OPEs, each of which was evaluated by two board certified anaesthesiologists randomly selected from a pool of 12. A key question of interest was to identify factors, for example, the length of training, didactic experience and other characteristics, that most influence OPE outcome. In addition, we were interested in assessing the reliability of the final grade, that is, the covariance parameters are of interest as well. However, estimating variance components in multi-level data with an unequal number of repeated ordinal outcomes presents several statistical challenges, such as how to estimate high dimensional random effects parameters, especially for ordinal outcomes. We propose a Bayesian hierarchical proportional odds model for data with such complexity. The flexibility of such a model allows us to make inference on the association of OPE outcomes with other factors and to estimate the variance components as well.

Anesthesiology↗

Shoot orientation affects vessel size, shoot hydraulic conductivity and shoot growth rate in Vitis vinifera L.

Vitis vinifera L. plants were grown in containers and each plant's single shoot was orientated upwards or downwards. Some plants were trained first upwards, then downwards, then again upwards (N-shaped plants). Vegetative growth was reduced in plants trained downwards compared to that in upward and N-shaped plants. Shoot growth rate slowed in downward shoot portions, but only after the apex had grown downwards for at least 10 internodes. Shoot hydraulic conductivity kh, measured after elimination of xylem embolisms, was lower in downward than in upward plants. In N-shaped plants kh was higher in the upward-growing shoot portions, and lower in the central, downward-growing portion. Shoot- and leaf-specific conductivities were also lower in downward than in upward shoot portions. Xylem cross-sectional area and xylem structure (number of wedges, number of vessels per unit xylem area) differed little in the three orientations. In contrast, vessel diameter and the sum of vessel cross-sectional areas were significantly smaller in downward than in upward shoot portions. These differences could explain the reduction in conductivity observed in the downward-orientated shoot portions. The measurements taken on N-shaped plants showed that the decreases in kh and in vessel size were a result of shoot orientation, not shoot bending.

Biological Transport↗

Consistency, inter-rater reliability, and validity of 441 consecutive mock oral examinations in anesthesiology: implications for use as a tool for assessment of residents.

BACKGROUND: Oral practice examinations (OPEs) are used extensively in many anesthesiology programs for various reasons, including assessment of clinical judgment. Yet oral examinations have been criticized for their subjectivity. The authors studied the reliability, consistency, and validity of their OPE program to determine if it was a useful assessment tool. METHODS: From 1989 through 1993, we prospectively studied 441 OPEs given to 190 residents. The examination format closely approximated that used by the American Board of Anesthesiology. Pass-fail grade and an overall numerical score were the OPE results of interest. Internal consistency and inter-rater reliability were determined using agreement measures. To assess their validity in describing competence, OPE results were correlated with in-training examination results and faculty evaluations. Furthermore, we analyzed the relationship of OPE with implicit indicators of resident preparation such as length of training. RESULTS: The internal consistency coefficient for the overall numerical score was 0.82, indicating good correlation among component scores. The interexaminer agreement was 0.68, indicating moderate or good agreement beyond that expected by chance. The actual agreement among examiners on pass-fail was 84%. Correlation of overall numerical score with in-training examination scores and faculty evaluations was moderate (r = 0.47 and 0.41, respectively; P < 0.01). OPE results were significantly (P < 0.01) associated with training duration, previous OPE experience, trainee preparedness, and trainee anxiety. CONCLUSION: Our results show the substantial internal consistency and reliability of OPE results at a single institution. The positive correlation of OPE scores with in-training examination scores, faculty evaluations, and other indicators of preparation suggest that OPEs are a reasonably valid tool for assessment of resident performance.

Anesthesiology↗

Mild hypothermia as a protective therapy during intracranial aneurysm surgery: a randomized prospective pilot trial.

OBJECTIVE: To conduct a pilot trial of mild intraoperative hypothermia during cerebral aneurysm surgery. METHODS: One hundred fourteen patients undergoing cerebral aneurysm clipping with (n = 52) (World Federation of Neurological Surgeons score < or =III) and without (n = 62) acute aneurysmal subarachnoid hemorrhage (SAH) were randomized to normothermic (target esophageal temperature at clip application of 36.5 degrees C) and hypothermic (target temperature of 33.5 degrees C) groups. Neurological status was prospectively evaluated before surgery, 24 and 72 hours postoperatively (National Institutes of Health Stroke Scale), and 3 to 6 months after surgery (Glasgow Outcome Scale). Secondary outcomes included postoperative critical care requirements, respiratory and cardiovascular complications, duration of hospitalization, and discharge disposition. RESULTS: Seven hypothermic patients (12%) could not be cooled to within 1 degrees C of target temperature; three of the seven were obese. Patients randomized to the hypothermic group more frequently required intubation and rewarming for the first 2 hours after surgery. Although not achieving statistical significance, patients with SAH randomized to the hypothermic group, when compared with patients in the normothermic group, had the following: 1) a lower frequency of neurological deterioration at 24 and 72 hours after surgery (21 versus 37-41%), 2) a greater frequency of discharge to home (75 versus 57%), and 3) a greater incidence of good long-term outcomes (71 versus 57%). For patients without acute SAH, there were no outcome differences between the temperature groups. There was no suggestion that hypothermia was associated with excess morbidity or mortality. CONCLUSION: Mild hypothermia during cerebral aneurysm surgery is feasible in nonobese patients and is well tolerated. Our results indicate that a multicenter trial enrolling 300 to 900 patients with acute aneurysmal SAH will be required to demonstrate a statistically significant benefit with mild intraoperative hypothermia.

Acute Disease↗

Lamotrigine concentrations in human serum, brain tissue, and tumor tissue.

PURPOSE: Although lamotrigine (LTG) has been used for years as an antiepilepic drug (AED), there are no data on penetration into the brain with the exception of a single case report. It was our aim to determine the LTG content in the brain and the tumor tissue and to bring the same into relation to the serum concentration and protein binding in neurosurgically operated patients. METHODS: Neurosurgical intervention was performed on 11 patients with brain tumors. Tumor tissue was removed, and LTG kinetics was carried out for 12 h. LTG was determined by means of (HPLC) and the protein binding by means of ultrafiltration. RESULTS: At the time of the section of the tumor, the LTG concentrations in the serum were an average of 3.7 microg/ml (range, 1.1-9.8); in the brain, an average of 6.8 microg/g (range, 1.0-14.9); and in the tumor, an average of 4.4 microg/g (range, 2.0-8.3). Brain/serum and tumor/serum ratios of 2.8 and 1.9, respectively, result from these data. The protein binding was on average 68% (range, 46-96). CONCLUSIONS: LTG is a lipophile AED with a moderate protein binding that penetrates brain tissue well and can be proven even in the tumor tissue.

Adult↗

Organization of a comprehensive anesthesiology oral practice examination program: planning, structure, startup, administration, growth, and evaluation.

STUDY OBJECTIVE: To describe the planning, structure, startup, administration, growth, and evaluation of a comprehensive oral practice examination (OPE) program. SETTING: Midwest U.S. anesthesiology residency training program. MEASUREMENTS AND MAIN RESULTS: Committee planning involved consideration of formal and frequency of administration, timing for best resident and faculty availability, communication, forms design, clerical support, record keeping, and quality monitoring. OPE format was deliberately constructed to resemble that used by the American Board of Anesthesiology (ABA) to enhance resident familiarity with ABA style oral examination. Quality improvement tools consisted of regular examiner and examinee inservice sessions, liaison with ABA associate examiners, and review of examinee exit questionnaires. A set of OPE databases was constructed to facilitate quality monitoring and educational research efforts. A semiannual administration schedule on three to four consecutive Mondays optimally accommodated resident rotations and faculty work schedules. Continued administration of the OPE program required ongoing construction of a pool of guided case-oriented questions, selection of appropriate questions based on examinee training exposure, examination calendar publication, and scheduling of recurring examiner and examinee activities. Important issues that required action by the governing committee were examination timing, conflict with clinical demands, use of OPE results, and procurement of training resources. The OPE program grew from 56 examinations in the first year to 120 exams by year 3. It was perceived positively by the majority of residents. There were 90.2% of exit questionnaires that acknowledged specific learning about oral examination technique, while only 0.3% indicated lack of meaningful information exchange. Fewer than 10% of responses indicated misleading questions or badgering by examiners. Resident preparedness increased with repeat OPE exposure. CONCLUSIONS: A comprehensive mock oral examination program was successfully planned, initiated, and developed. It is well accepted by residents and faculty. Its inception was associated with an increase in resident preparedness. Now in its tenth year of existence it continues to be an asset and essential component of our training program.

Anesthesiology↗

Effects of omega-3 fatty acids on renal function and electrolyte excretion in aged persons.

Prostaglandin (PG) E2 formation, especially relevant for renal function in the state of renal vascular disease, is inhibited by omega-3 fatty acids. On the other hand, omega-3 fatty acids are under evaluation in chronic inflammatory kidney diseases, because of their ability to modulate immunologic cell response. We evaluated the effect of 1.7 g/d eicosapentaenoic acid (EPA), given with cod liver oil for four weeks to elderly persons with atherosclerosis. Enrichment of EPA coincided with inhibition of PG biosynthesis, transiently plasma creatinine increased, while creatinine clearance and excretion of solutes with the urine decreased in our experimental subjects. At the end of the four week study no effect of omega-3 fatty acids on renal function was found. Further studies are warranted to evaluate the potential benefit of omega-3 fatty acids on renal function in elderly persons.

Aged↗

Heart rate variability and the prone position under general versus spinal anesthesia.

STUDY OBJECTIVE: To evaluate heart rate (HR) variability in the prone position with power spectral heart rate (PSHR) analysis during spinal and general anesthesia. DESIGN: Prospective, clinical evaluation of HR variability in the prone position. SETTING: Tertiary care teaching hospital. PATIENTS: 20 healthy, ASA physical status I and II patients scheduled for elective lumbar spine surgery in the prone position. INTERVENTIONS: Anesthetic technique was either a standard general anesthetic or spinal anesthetic, based on the preference of the patient. Power spectral heart rate, HR, and blood pressure (BP) readings were determined prior to anesthetic intervention and as soon as a stable PSHR reading was available in the prone position. MEASUREMENTS AND MAIN RESULTS: Heart rate and BP were recorded at baseline prior to anesthesia and at the time of stable PSHR data in the prone position. Power spectral heart rate data included low-frequency activity (LFa), high-frequency activity (HFa), and the ratio (LFa/HFa). Spinal anesthesia level was recorded by thoracic dermatome at complete onset. Data were collected from 20 patients; 12 patients chose spinal anesthesia and 8 chose general anesthesia. The prone position resulted in significant increase in HR in the spinal group and significant decrease in BP in the general anesthesia group. Low-frequency activity and LFa/HFa ratio were unchanged in the spinal anesthesia group and were significantly decreased in the general anesthesia group. Spinal level was T8.7. CONCLUSIONS: The association of less change in LFa activity and preservation of BP on assumption of the prone position in patients during low spinal anesthesia suggests better preservation of autonomic nervous system compensatory mechanisms during low spinal anesthesia than with general anesthesia.

Anesthesia, General↗

The influence of scalp infiltration with bupivacaine on hemodynamics and postoperative pain in adult patients undergoing craniotomy.

UNLABELLED: After craniotomy, hypertension may contribute to intracerebral hemorrhage. We studied whether scalp infiltration with bupivacaine during craniotomy reduces postoperative pain and hypertension. In a double-blind fashion, 36 adult patients (ASA physical status II or III) undergoing elective craniotomy were randomly assigned to receive scalp infiltration with either bupivacaine (0.25%) and epinephrine (1:200,000) or saline/ epinephrine (1:200,000) for skeletal fixation, skin incision, and wound closure. Heart rate (HR) and mean arterial pressure (MAP) were measured after anesthesia induction, after skull-pin insertion, after scalp infiltration, during dural closure, during skin closure, on admission to postanesthesia care unit (PACU), and 1 h after admission. Visual analog pain scores were recorded in the PACU. MAP was significantly greater in the saline group at scalp infiltration. HR was significantly faster in the saline group at dural and skin closure. The bupivacaine group reported significantly less pain than the saline group at PACU admission and 1 h after admission. Pain scores did not correlate with hemodynamic measurements. We conclude that scalp infiltration with 0.25% bupivacaine with 1:200,000 epinephrine blunts certain intraoperative hemodynamic responses and reduces postoperative pain but has no effect on postoperative hemodynamics. IMPLICATIONS: We sought to evaluate whether scalp infiltration with bupivacaine and epinephrine at the beginning and end of craniotomy would afford more intra- and postoperative hemodynamic stability and influence immediate postoperative pain. We found that intraoperative hemodynamics were not influenced greatly; however, craniotomy patients do have significant postoperative pain, which does not seem to have an influence on hemodynamics in the postanesthesia care unit.

Adolescent↗