Comparison of cerebral oximeter and evoked potential monitoring in carotid endarterectomy

PURPOSE: To assess the cerebral oximeter, which measures regional oxygen saturation (rSO2) continuously and noninvasively, as a cerebral monitor during carotid endarterectomy (CEA). The rSO2 was compared with Somatosensory Evoked Potentials (SSEPs) as an indicator for shunting and as a predictor of postoperative neurological deficits. METHODS: Seventy-two consenting patients undergoing CEA with general anaesthesia were studied. Normocarbia, normothermia and normotension were maintained. Cerebral monitoring consisted of bilateral median nerve SSEPs and the INVOS 3100 cerebral oximeter with the sensor pad placed on the ipsilateral forehead. Decreases in SSEP amplitude of 50% and in rSO2 of 10% were considered clinically significant. Neurological assessment was performed at emergence from anaesthesia, 24 hr postoperatively and at discharge. The rSO2 changes were compared with SSEP changes and with neurological deficits. Statistical analysis was with chi square and analysis of variance P < 0.05 was considered significant. RESULTS: During carotid artery clamping, rSO2 decreased from 72 +/- 8% to 68 +/- 9% and mean arterial blood pressure increased from 92 +/- 14 mmHg to 98 +/- 14 mmHg. In four patients, the carotid artery was shunted because of SSEP changes after cross-clamping. Five patients had > or = 10% decreases in rSO2 following clamp application. Changes in both SSEP and rSO2 occurred in two patients. Three of the four shunted patients had transient postoperative neurological deficits. One patients had a transient deficit without changes in either monitor. There were no persistent postoperative deficits. Compared with SSEPs, rSO2 had a sensitivity of 50% and a specificity of 96%. CONCLUSION: Clinical experience with this evolving technology is ongoing. Its role in neurovascular procedures has yet to be established.     

Risk assessment on the carcinogenic potential of hybridoma cell DNA: implications for residual contaminating cellular DNA in biological products

Fifty people (25 at risk for an eating disorder, 25 controls) performed a simple reaction-time (SRT) task and a negative-priming (NP) task. The two groups did not differ on the SRT task. For the NP task, the controls displayed the NP effect (responses on critical trials were slower than responses on control trials). At-risk participants, however, revealed no such NP effect. Although the pattern of NP performance in the at-risk participants may indicate that they as a group had deficiencies in their ability to inhibit irrelevant information, it is also possible that issues related to obsessionality, perfectionism, and restraint in the at-risk group affected the results.     

Role of aspartate 70 and tryptophan 82 in binding of succinyldithiocholine to human butyrylcholinesterase

The atypical variant of human butyrylcholinesterase has Gly in place of Asp 70. Patients with this D70G mutation respond abnormally to the muscle relaxant succinyldicholine, experiencing hours of apnea rather than the intended 3 min. Asp 70 is at the rim of the active site gorge 12 A from the active site Ser 198. An unanswered question in the literature is why the atypical variant has a 10-fold increase in Km for compounds with a single positive charge but a 100-fold increase in Km for compounds with two positive charges. We mutated residues Asp 70, Trp 82, Trp 231, Glu 197, and Tyr 332 and expressed mutant enzymes in mammalian cells. Steady-state kinetic parameters for hydrolysis of butyrylthiocholine, benzoylcholine, succinyldithiocholine, and o-nitrophenyl butyrate were determined. The wild type and the D70G mutant had identical k(cat) values for all substrates. Molecular modeling and molecular dynamics suggested that succinyldicholine could bind in two consecutive orientations in the active site gorge; formation of one complex caused a conformational change in the omega loop involving Asp 70 and Trp 82. We propose the formation of three enzyme-substrate intermediates preceding the acyl-enzyme intermediate; kinetic data support this contention. Substrates with a single positive charge interact with Asp 70 just once, whereas substrates with two positive charges, for example succinyldithiocholine, interact with Asp 70 in two complexes, thus explaining the 10- and 100-fold increases in Km in the D70G mutant.     

Shear stress gradients remodel endothelial monolayers in vitro via a cell proliferation-migration-loss cycle

Wall shear stress has been implicated in the genesis of atherosclerosis because a strong correlation exists between the location of developing arterial lesions and regions where particular gradients in stress occur. Studying the behavior of endothelial cells in such regions may contribute to our understanding of the disease etiology. We report the detailed migratory history of endothelial cells subjected to large shear stress gradients caused by a surface protuberance in an in vitro model system. The history of cell migration, cell division, and cell loss from the surface was continuously monitored in confluent human umbilical vein endothelial cell monolayers for 48 hours after the onset of flow. Individual cells were tracked using time-lapse video microscopy. In contrast to a uniform laminar flow field in which cells were observed to continually rearrange their relative position with no net migration, in a disturbed flow field there was a net migration directed away from the region of high shear gradient. This organized migration pattern under disturbed flow conditions was accompanied by more than a twofold increase in cell motility. In addition, cell division increased in the vicinity of the flow separation (maximum shear stress gradient of 34 dyne/cm2 per mm) whereas cell loss was increased upstream and downstream in the regions where the shear gradient diminishes. These data suggest a steady cell proliferation-migration-loss cycle and indicate that local shear stress gradient may play a key role in the morphological remodeling of the vascular endothelium in vivo.     

The impact of prostanoids on pulmonary gas exchange during abdominal surgery with mesenteric traction

We investigated the effect of intravenous (iv) ibuprofen on prostanoid release and on pulmonary gas exchange after abdominal mesenteric traction (MT) during either abdominal aortic surgery or pancreas resection. In a prospective, randomized, double-blind study, 400 mg ibuprofen (pancreas n = 13, aorta n = 13) or a placebo (pancreas n = 13, aorta n = 13) was administered iv before skin incision. MT was applied uniformly. The prostanoid plasma concentrations, venous admixture (Q(va)/Q(t)), and PaO2/FIO2 ratio were determined at baseline (before MT) and 5, 15, 45, and 90 min after MT. Patients who underwent aortic surgery were older and exhibited a lower preoperative PaO2 than those who underwent pancreas resection. Placebo-treated patients revealed a 30-fold peak increase in 6-keto-prostaglandin F1alpha (stable metabolite of prostacyclin) levels after intentional MT during aortic as well as pancreatic operations. This response was accompanied by an increase in Q(va)/Q(t) (ibuprofen: pancreas 7% +/- 1%, aorta 14% +/- 2%; placebo: pancreas 16% +/- 3%, aorta 26% +/- 3%/15 min after MT [mean +/- SEM, P < 0.05, placebo vs ibuprofen]), which resulted in decreased PaO2/ FIO2 ratio only in the aortic surgery patients (ibuprofen: 310 +/- 19; placebo: 237 +/- 24 15 min after MT, [mean +/- SEM, P < 0.05]). The authors conclude that ibuprofen-pretreated patients demonstrated almost constant prostanoid levels without changes in pulmonary gas exchange after MT.     

Effects of interview mode on bias in survey measurements of drug use: do respondent characteristics make a difference?

Three recent empirical studies have provided strong evidence that self-administered questionnaires (SAQs), compared with interviewer questioning, substantially improve the reporting of drug use in population surveys. Specifically, SAQs appear to diminish underreporting bias. Two of these studies previously reported that this effect of interview mode varied significantly across gender, race/ethnicity, and age. Data from a randomized experiment embedded in the 1990 National Household Survey of Drug Abuse (NHSDA) field test were reanalyzed to test for those interaction effects. To better replicate prior studies, the NHSDA field test sample was restricted to people ages 18 to 45 (N = 1,877). The results of our statistical analyses generally replicated the finding of a main effect of SAQs on the reporting of drug use. However, only weak evidence was found to support the hypothesis that the advantage of SAQs varies substantially by the gender, race/ethnicity, or age of the respondent.     

Sleep-disordered breathing in amyotrophic lateral sclerosis

OBJECTIVES: Our study was designed to determined the significance of aortogenic embolism in an unselected autopsy collective. BACKGROUND: Although embolism arising from atherosclerotic plaques in the aorta has been acknowledged, the role of aortic atheromatosis among other well known sources of embolism remains to be further clarified. METHODS: We examined the proximal part of the arterial system with regard to the presence of atherosclerotic lesions as well as cardiac changes in 120 consecutive necropsy studies. Pathologic evidence of embolic events was recorded. Clinical and neuropathologic data were also surveyed in all patients. RESULTS: Among atherosclerotic lesions, fibrous plaques (p < 0.05) and calcified (p < 0.0001) and ulcerated lesions (p < 0.0001) as well as thrombi (p < 0.005) were observed significantly more frequently in the aortic arch and in the descending aorta than in the ascending aorta, whereas fatty streaks were distributed uniformly. In 40 (33%) of the 120 patients, we found pathologic evidence of arterial embolization. Multiple logistic regression analysis revealed a significant correlation between embolism and complicated atherosclerotic plaques in the aortic arch (odds ratio [OR] 5.8, 95% confidence interval [CI] 1.1 to 31.7, p < 0.05), severe ipsilateral carotid artery disease (OR 3.1, 95% CI 3.1 to 45.3, p < 0.001) and atrial fibrillation (OR 3.5, 95% CI 1.1 to 9.9, p < 0.05). CONCLUSIONS: Complicated atherosclerotic plaques in the aortic arch represent an independent risk factor for systemic embolism similar to atrial fibrillation and severe atherosclerosis of the carotid arteries.     

Management of the buried penis in adults

PURPOSE: Buried penis, most commonly seen in children, is particularly debilitating in adults, resulting in the inability to void standing and it affects vaginal penetration. The pathophysiology, including scar contracture of the distal soft tissue and skin envelope with concurrent descent of the abdominal fat pad, represents a surgical challenge. We developed a management algorithm to evaluate and treat adults with buried penis. MATERIALS AND METHODS: From January 1, 1994 to May 1, 1996, 7 patients 23 to 66 years old presented with buried penis. Diabetes mellitus, a common co-morbid condition, was present in 5 patients, and 5 of 7 were morbidly obese. RESULTS: Surgical correction was performed in 5 patients with excellent results in 3. Resection of scar contracture was sufficient to provide adequate length and none required release of the suspensory ligament. Panniculectomy was performed in 1 patient. One man requiring a graft to achieve adequate penile coverage required reoperation. This patient had undergone a previous attempted repair with extensive contracture. All patients regained potency postoperatively. CONCLUSIONS: With appropriate planning and adherence to basic reconstructive surgical principles, correction of the buried penis can yield a high success rate.     

Development and validation of a visual acuity chart for Australian Aborigines and Torres Strait Islanders

Portal hypertension syndrome is a common evolutive complication of several hepatic and extrahepatic diseases, being liver cirrhosis responsible for more than 80% of cases. When diagnosed it has prognostic value because of the high incidence of hemorrhagic, metabolic and infectious complications that these patients may develop. Clinical suspicion must be confirmed by objective complementary studies that provide information about the etiology and severity of the disease. In this review article we describe the contribution of ultrasonography in the evaluation of patients with portal hypertension as an objective diagnostic method and the usefulness of doppler ultrasound in the non-invasive hemodynamic assessment of the splanchnic and portal circulation.     

A novel type I receptor serine-threonine kinase predominantly expressed in the adult central nervous system

Receptor serine-threonine kinases (RSTK) mediate inhibitory as well as stimulatory signals for growth and differentiation by binding to members of the transforming growth factor-beta (TGF-beta) superfamily. Over 12 different RSTKs have been isolated so far, displaying wide expression in peripheral tissues and in the nervous system. Here we report the isolation and characterization of a novel type I RSTK termed activin receptor-like kinase-7 (ALK-7) that, unlike other members of this receptor family, is predominantly expressed in the adult central nervous system. The ALK-7 gene encodes a 55-kDa cell-surface protein that exhibits up to 78% amino acid sequence identity in the kinase domain to previously isolated type I receptors for TGF-beta and activin. In the extracellular domain, however, ALK-7 is more divergent, displaying comparable similarities with all members of the ALK subfamily. RNase protection and in situ hybridization studies demonstrated a highly specific mRNA distribution restricted to neurons in several regions of the adult rat central nervous system, including cerebellum, hippocampus, and nuclei of the brainstem. Receptor reconstitution and cross-linking experiments indicated that ALK-7 can form complexes with type II RSTKs for TGF-beta and activin in a ligand-dependent manner, although direct binding of ALK-7 to ligand in these complexes could not be demonstrated. The specific expression pattern of ALK-7, restricted to the postnatal central nervous system, indicates that this receptor may play an important role in the maturation and maintenance of several neuronal subpopulations.