Propofol and Sevoflurane in Subanesthetic Concentrations Act Preferentially on the Spinal Cord: Evidence from Multimodal Electrophysiological Assessment

Background: Animal experiments in recent years have shown that attenuation of motor responses by general anesthetics is mediated at least partly by spinal mechanisms. Less is known about the relative potency of anesthetic drugs in suppressing cortical and spinal electrophysiological responses in vivo in humans, particularly those, but not only those, connected with motor responses. Therefore, we studied the effects of sevoflurane and propofol in humans using multimodal electrophysiological assessment.

Methods: We studied nine healthy volunteers in two sessions during steady state sedation with 0.5, 1.0, and 1.5 [mu]g/l (targeted plasma concentration) propofol or 0.2 and 0.4 vol% (end-tidal) sevoflurane. Following a 15-min equilibration period, motor responses to transcranial magnetic stimulation and peripheral (H-reflex, F-wave) stimulation were recorded, while electroencephalography and auditory evoked responses were recorded in parallel.

Results: At concentrations corresponding to two thirds of C50 awake, motor responses to transcranial magnetic stimulation were reduced by approximately 50%, H-reflex amplitude was reduced by 22%, F-wave amplitude was reduced by 40%, and F-wave persistence was reduced by 25%. No significant differences between sevoflurane and propofol were found. At this concentration, the Bispectral Index was reduced by 7%, and the middle-latency auditory evoked responses were attenuated only mildly (Nb latency increased by 11%, amplitude PaNb did not change). In contrast, the postauricular reflex was suppressed by 77%.     

Establishment of ionic channels and signalling cascades in the embryonic stem cell-derived primitive endoderm and cardiovascular system

The first organ system to be established in early embryogenesis is the cardiovascular system which develops upon interaction with hypoblastic cells of the primitive endoderm. Here we focus on recent work on embryoid bodies derived from pluripotent embryonic stem (ES) cells. Ca(2+) oscillations and Ca(2+) signalling pathways during the differentiation of primitive endodermal cell layers are reported. Furthermore, the development-dependent expression of ion channels and the buildup of signalling cascades involved in the modulation of voltage-dependent L-type Ca(2+) channels during early cardiomyogenesis and the formation of functional vascular structures in the process of vasculogenesis and angiogenesis are reviewed. We also report on the use of green fluorescent protein reporter gene expression under the control of cardiac-specific promoters, e.g. the human cardiac alpha-actin promoter, which enables the identification and in vivo characterization of cardiomyocytes at very early stages of cardiomyogenesis.     

Tuberculosis in hemodialysis patients in New Jersey: a statewide study.

OBJECTIVE: To study the incidence of tuberculosis (TB), tuberculin skin testing (TST) practices, and infection control practices at outpatient hemodialysis centers. DESIGN: Mail surveys performed in December 1994 and 1995. MAIN OUTCOME MEASURES: The numbers of patients with incident active TB during 1994 and 1995, TST policies during 1994, and TB infection control policies in 1994. SETTING: All outpatient dialysis centers in New Jersey. PATIENTS OR PARTICIPANTS: Healthcare workers and patients in dialysis centers in New Jersey. RESULTS: Of 47 centers, 41 provided information on TST and TB infection control policies and practices. TSTs were performed on newly hired healthcare workers at all 41 centers and on established workers at 39 centers. In contrast, only 1 center reported performing TSTs on hemodialysis patients; 5 other centers reported screening of patients for TB using chest radiographs. Active TB was reported in 3 of 4,550 chronic hemodialysis patients in 1994 (rate, 66/100,000 patient-years) and in 4 of 4,831 patients in 1995 (rate, 83/100,000 patient-years). Both rates were several times higher than the rate in the New Jersey general population during this period (10.7-10.8/100,000). CONCLUSION: Although based on small numbers of patients with TB, we found a relatively high incidence of TB among hemodialysis patients in New Jersey. Most centers reported performing TSTs on workers but not on patients. These results suggest the need for improved TB screening and infection control precautions at outpatient dialysis centers.     

Transit time ultrasound perivascular flow probe technology is superior to MR imaging on hepatic blood flow measurement in a porcine model

Background: The hepatic hemodynamics is an essential parameter in surgical planning as well as in various disease processes. The transit time ultrasound(TTUS) perivascular flow probe technology is widely used in clinical practice to evaluate the hepatic inflow, yet invasive. The phase-contrast-MRI(PC-MRI) is not invasive and potentially applicable in assessing the hepatic blood flow. In the present study, we compared the hepatic inflow rates using the PC-MRI and the TTUS probe, and evaluated their predictive value of post-hepatectomy adverse events. Methods: Eighteen large white pigs were anaesthetized for PC-MRI and approximately 75% hepatic resection was performed under a unified protocol. The blood flow was measured in the hepatic artery(Qha), the portal vein(Qpv), and the aorta above the celiac trunk(Qca) using PC-MRI, and was compared to the TTUS probe. The Bland-Altman method was conducted and a partial least squares regression(PLS) model was implemented. Results: The mean Qpv measured in PC-MRI was 0.55 ± 0.12 L/min, and in the TTUS probe was 0.74 ± 0.17 L/min. Qca was 1.40 ± 0.47 L/min in the PC-MRI and 2.00 ± 0.60 L/min in the TTUS probe. Qha was 0.17 ± 0.10 L/min in the PC-MRI, and 0.13 ± 0.06 L/min in the TTUS probe. The Bland-Altman method revealed that the estimated bias of Qca in the PC-MRI was 32%(95% CI:-49% to 15%); Qha 17%(95% CI:-15% to 51%); and Qpv 40%(95% CI:-62% to 18%). The TTUS probe had a higher weight in predicting adverse outcomes after 75% resection compared to the PC-MRI( β= 0.35 and 0.43 vs β = 0.22 and 0.07, for tissue changes and premature death, respectively). Conclusions: There is a tendency of the PC-MRI to underestimate the flow measured by the TTUS probes. The TTUS probe measures are more predictive of relevant post-hepatectomy outcomes.     

Percutaneous fetoscopic patch closure of human spina bifida aperta: advances in fetal surgical techniques may obviate the need for early postnatal neurosurgical intervention

Background  A percutaneous minimally invasive fetoscopic approach was attempted for closure of a spina bifida aperta in two fetuses with L5 lesions. The goal was to obviate the need for postnatal neurosurgery to manage this condition. Methods and Results  The percutaneous fetoscopic procedures were performed by a two-layer approach at respectively 22 ± 2 and 22 ± 4 weeks of gestation. The fetuses were delivered respectively at 32 ± 6 and 32 + 3 weeks of gestation. Their neural cords were completely covered although in small areas skin closure was incomplete. Postnatally, complete skin closure occurred beneath an occlusive draping within 2 to 3 weeks such that neurosurgical intervention was not required. Both neonates showed reversal of hindbrain herniation, near-normal leg function, and satisfactory bladder and bowel function. For one of the two fetuses, ventriculoperitoneal shunt insertion was not required. Conclusions  Percutaneous minimally invasive fetoscopic patch closure of spina bifida aperta offers a substantially less maternal trauma than open fetal surgical repair and currently may even obviate the need for postnatal neurosurgical repair. With a little further improvement in surgical techniques and a better understanding of incorporating surgical patches into the fetus, complete skin closure seems possible in the near future.     

Low dose unenhanced helical computerized tomography for the evaluation of acute flank pain

PURPOSE: Unenhanced helical computerized tomography (CT) has proved to be an excellent diagnostic tool for evaluating acute flank pain with reported 95% to 100% sensitivity, 92% to 100% specificity, 96% to 100% positive and 91% to 100% negative predictive values. The diagnostic value of a new low dose protocol was prospectively studied and compared with the results of conventional unenhanced helical CT in a previous series with an effective dose equivalent (HE) of 3.1 to 4.3 mSv. and in current literature with an estimated HE of 4.3 to 4.7 mSv. MATERIALS AND METHODS: In 109 patients 18 to 86 years old with acute flank pain we performed low dose unenhanced helical CT in addition to abdominal ultrasound and urinalysis with new CT parameters (120 kV. 70 mA., 5 mm. collimation, pitch 2 and incremental reconstruction each 5 mm.) that led to a more than 50% decrease in radiation exposure to 1.50 mSv. in females and 0.98 mSv. in males. Ureteral calculi were confirmed or excluded by retrograde ureteropyelography in 51 cases. In the other cases the diagnosis was verified by the clinical and ultrasound course, and/or stone asservation. RESULTS: In 80 of the 109 patients the flank pain was caused by a ureteral calculus. Low dose unenhanced helical CT precisely identified 77 ureteral calculi with 1 false-positive finding. Thus, the sensitivity and specificity of low dose unenhanced helical CT were 96% and 97% with a 99% positive and 90% negative predictive value. In 15 of 29 patients with CT findings negative for stone disease different causes of pain were established by low dose unenhanced helical CT. CONCLUSIONS: Even with the significantly decreased radiation exposure of the low dose protocol unenhanced helical CT is still an excellent and rapid diagnostic tool for evaluating acute flank pain with lower radiation exposure than excretory urography (HE 1.3 to 2.3 mSv.) at our departments. Only in obese patients with a body mass index of greater than 31 kg./m.2 is conventional unenhanced helical CT with higher radiation exposure recommended to achieve adequate image quality.     

Passive smoking exposure and female breast cancer mortality

BACKGROUND: Several studies have reported positive associations between environmental tobacco smoke (ETS) and increased risk of breast cancer. However, studies of active smoking and risk of breast cancer are equivocal and in general do not support a positive association. To try to resolve this paradox, we examined the association between breast cancer mortality and potential ETS exposure from spousal smoking in an American Cancer Society prospective study of U.S. adult women. METHODS: We assessed breast cancer death rates in a cohort of 146 488 never-smoking, single-marriage women who were cancer free at enrollment in 1982. Breast cancer death rates among women whose husbands smoked were compared with those among women married to men who had never smoked. Cox proportional hazards modeling was used to control for potential risk factors other than ETS exposure. RESULTS: After 12 years of follow-up, 669 cases of fatal breast cancer were observed in the cohort. Overall, we saw no association between exposure to ETS and death from breast cancer (rate ratio [RR] = 1.0; 95% confidence interval [CI] = 0.8-1.2). We did, however, find a small, not statistically significant increased risk of breast cancer mortality among women who were married before age 20 years to smokers (RR = 1. 2; 95% CI = 0.8-1.8). CONCLUSIONS: In contrast to the results of previous studies, this study found no association between exposure to ETS and female breast cancer mortality. The results of our study are particularly compelling because of its prospective design as compared with most earlier studies, the relatively large number of exposed women with breast cancer deaths, and the reporting of exposure by the spouse rather than by proxy.