Brain abscess and brain tumor: discrimination with in vivo H-1 MR spectroscopy

An experiment is reported examining the relation of implicit grammar learning and series completion tasks to a standard measure of psychometric intelligence, the Wechsler Adult Intelligence Scale-Revised (WAIS-R; D. Wechsler, 1981). The results replicate and extend an earlier study by A. S. Reber, F. F. Walkenfeld, and R. Hernstadt (1991) and provide the following support for the differences between explicit and implicit tasks: (a) The implicit task was less strongly related to Full Scale IQ, and (b) the implicit task appeared to be independent of age. The implicit and explicit tasks exhibited a quite different pattern of relations to the factors known to underlie WAIS-R performance. Although both tasks showed significant links with a Perceptual Organization factor, only the series completion task showed a significant link with the Attention factor.     

Clonidine for major vascular surgery in hypertensive patients: a double-blind, controlled, randomized study

The utility of clonidine for hypertensive patients presenting for major vascular procedures remains debatable. Twenty-one hypertensive patients presenting for aortic surgery were given clonidine (n = 11) or placebo (n = 10) in a double-blind, randomized manner. Clonidine was administered 6 micrograms/kg per os 120 min before induction of anesthesia and 3 micrograms/kg intravenously (i.v.) over 60 min from aortic declamping to skin closure. Anesthesia was induced with alfentanil 20 micrograms/kg, midazolam, and atracurium and maintained with nitrous oxide 70%, an alfentanil infusion (0.25 microgram.kg-1. min-1), and isoflurane. Anesthetic requirements, circulatory variables, interventions, and isoproterenol dose-response curves (pre- and postoperatively) were determined. Plasma concentrations of clonidine, alfentanil, and vasoactive hormones were measured. When the clonidine group was compared with the placebo group, (a) isoflurane, alfentanil, and midazolam requirements were reduced by 38%, 42%, and 41%, respectively (P = 0.04, 0.03, 0.0002, respectively); (b) supplemental circulatory and anesthetic adjustments were reduced by 51% (P = 0.0006); (c) interventions with vasopressors were not significantly increased (placebo: two; clonidine: five); (d) systolic and mean arterial pressures and heart rate were reduced; (e) increases in norepinephrine, epinephrine, and plasma renin activity were suppressed, whereas vasopressin surge was attenuated; and (f) chronotropic response to isoproterenol was unaffected. Clonidine was effective in reducing anesthetic requirements and in improving circulatory stability in hypertensive patients presenting for major vascular procedures.     

Rapid transepithelial antigen transport in rat jejunum: impact of sensitization and the hypersensitivity reaction

BACKGROUND & AIMS: Intestine from sensitized rats develops a rapid secretory response to luminal antigen challenge that depends on activation of subepithelial mast cells. The aim of this study was to determine the timing and route of the transepithelial protein antigen transport. METHODS: Rats were sensitized to horseradish peroxidase (HRP). After 10-14 days, jejunal segments were resected, mounted in Ussing chambers, and challenged with HRP on the luminal side. RESULTS: Electron microscopy of tissue specimens fixed at 2 minutes (before mast cell activation) showed enhanced endocytic uptake of HRP in enterocytes of HRP-sensitized rats compared with ovalbumin-sensitized or saline-injected controls. At this time, HRP was distributed throughout epithelial cells and was already evident in the lamina propria. In contrast, HRP was restricted to the apical region of enterocytes in controls. At 30 minutes (after mast cell activation), in HRP-sensitized rats only, HRP was also located within tight junctions and the paracellular region between epithelial cells. Tissue conductance was increased in HRP-sensitized rats beginning 30 minutes after HRP addition and correlated with the overall flux of HRP across the tissue. CONCLUSIONS: The results show that specific sensitization enhances the initial uptake and transcytosis of antigen across intestinal epithelium. Subsequent to activation of mast cells, antigen transport is further enhanced by penetration through the paracellular pathway.     

The specific bronchial provocation test in the diagnosis of occupational asthma

Specific bronchial challenge (SBC) testing is a key technique for diagnosing the origin of occupational asthma (OA). SBC is indicated in specific circumstances, including whenever several agents present in the work environment may be the cause of OA, when new or unusual occupational agents need to be identified, when evidence for legal action is required, or when research is conducted. SBC procedures are not standardized, because of the great diversity of occupational agents and the variety of physical and chemical properties involved. Thus, SBC testing with agents found in fumes, gases or vapors can be administered in special cabins or in closed circuits with continuous monitoring of sub-irritant concentrations. Agents found in dust, most but not all of which have high molecular weights, may be appropriate for routine SBC testing in an allergy laboratory. This paper will treat only these cases. SBC must be formed in specialized centers by experienced personnel, as it is a sophisticated and potentially dangerous technique. We describe a series of 20 patients diagnosed of OA in our unit over the past two years in whom SBC provided an etiologic diagnosis. All were exposed to dust or aerosols at work. The cause was a substance of high molecular weight in 17 cases, and low molecular weight in 3. The procedure used is described and models of bronchial response are discussed.     

Evaluating the potential cost-effectiveness of stenting as a treatment for symptomatic single-vessel coronary disease. Use of a decision-analytic model

BACKGROUND: Coronary stenting appears to provide more predictable immediate results and lower rates of restenosis than conventional balloon angioplasty for selected lesion types, but its hospital costs are significantly higher. This study was designed to evaluate the potential cost-effectiveness of Palmaz-Schatz coronary stenting relative to conventional balloon angioplasty for the treatment of patients with symptomatic, single-vessel coronary disease. METHODS AND RESULTS: We developed a decision-analytic model to predict quality-adjusted life expectancy and lifetime treatment costs for patients with symptomatic, single-vessel coronary disease treated by either Palmaz-Schatz stenting (PSS) or conventional angioplasty (PTCA). Estimates of the probabilities of overall procedural success (PTCA, 97%; PSS, 98%), abrupt closure requiring emergency bypass surgery (PTCA, 1.0%; PSS, 0.6%), and angiographic restenosis (PTCA, 37%; PSS, 20%) were derived from review of the literature published as of September 1993. Procedural costs were based on the true economic (ie, variable) costs of each procedure at Boston's Beth Israel Hospital. On the basis of these data, coronary stenting was estimated to result in a higher quality-adjusted life expectancy than conventional angioplasty but to incur additional costs as well. Compared with conventional angioplasty, stenting had an estimated incremental cost-effectiveness ratio of $23,600 per quality-adjusted life year gained. Although the cost-effectiveness ratio for stenting changed with variations in assumptions about the relative costs and restenosis rates, it remained less than $40,000 per quality-adjusted year of life gained--and thus was similar to many other accepted medical treatments--unless the stent angiographic restenosis rate was > 23%, the angioplasty restenosis rate was < 34%, or the cost of stenting (including vascular complications) exceeded that of conventional angioplasty by more than $3000. The alternative strategy of secondary stenting (initial angioplasty followed by stenting only for symptomatic restenosis) was estimated to be both less effective and less cost-effective than primary stenting over a wide range of plausible assumptions and thus does not appear to be cost-effective when primary stenting is also an option. CONCLUSIONS: Decision-analytic modeling can be used to evaluate the potential cost-effectiveness of new coronary interventions. Our analysis suggests that despite its higher cost, elective coronary stenting may be a reasonably cost-effective treatment for selected patients with single-vessel coronary disease. Primary stenting is unlikely to be cost-effective for lesions with a low probability of restenosis (eg, < 30%) or for patients for whom the cost of stenting is expected to be much higher than usual (eg, because of a high risk of vascular complications). Given the sensitivity of the cost-effectiveness ratios to even modest variations in the relative restenosis rates and cost estimates, future studies will be necessary to determine more precisely the cost-effectiveness of coronary stenting for specific patient and lesion subsets.     

Reliability of individual umbilical artery pH measurements

OBJECTIVE: This study examined the effect of incarceration during pregnancy on infant birth weight. METHODS: North Carolina prison records were matched to North Carolina birth certificates and health services records to identify 94 women who were incarcerated during one pregnancy but not incarcerated during another pregnancy. Paired analyses examined differences between the pregnancies in terms of the women's characteristics and use of health services. A generalized estimating equations analysis modeled infant birth weight as a function of the number of days that a woman was incarcerated during pregnancy, accounting for the correlation between the birth weights of two infants born to the same mother and several potentially confounding variables. RESULTS: Since the women were significantly more likely to have been incarcerated during the second of the pair of pregnancies, as a group they were significantly older and had more children at the time of the incarcerated pregnancy than at the time of the home pregnancy. After controlling for important covariates, a higher number of pregnancy days spent incarcerated was found to be associated with higher infant birth weight. CONCLUSION: These findings suggest that aspects of the prison environment such as shelter and regular meals may enhance pregnancy outcomes among very high risk women. Health professionals should join others in efforts to assure that health-promoting resources such as adequate shelter, nutritional support, and substance abuse treatment programs are available to all pregnant women.     

Liver microsomal membrane fluidity and microsomal desaturase activities in adult spontaneously hypertensive rats

OBJECTIVE: The purpose of the present study was to investigate liver microsomal membrane fluidity simultaneously with membrane fatty acid composition and desaturase activities in spontaneously hypertensive rats (SHR). DESIGN AND METHODS: The membrane fluidity was determined, after electron spin resonance (ESR) measurement, in SHR compared with normotensive Wistar-Kyoto (WKY) rats, by calculating the order parameter S from ESR spectra of 5-nitroxide stearate and 10-nitroxide stearate, used as spin-labelled fatty acids. Desaturase activities were measured by incubating SHR and WKY rat liver microsomes with [14C]-radiolabeled fatty acids as substrates for desaturation reactions. The fatty acid composition of liver microsomal membranes was determined by gas-liquid chromatography. RESULTS: Whereas no significant difference between S of 5-nitroxide stearate was observed for SHR and WKY rats, S of 10-nitroxide stearate was significantly lower in SHR than it was in WKY rat microsomal membrane, indicating that the core microsomal membrane fluidity was higher in SHR. Significant differences between fatty acid compositions were observed for SHR and WKY rat microsomal membranes. Delta9 and n-6 delta6 microsomal desaturase activities were significantly lower in SHR. CONCLUSION: These results suggest that the higher liver core microsomal membrane fluidity observed in SHR might be dependent on the increased proportion of mono-unsaturated fatty acids. Such observed modifications and the alterations in delta9 and n-6 delta6 desaturase activities suggest that an impaired polyunsaturated fatty acid biosynthesis is related to changes in microsomal membrane fluidity in hypertension.     

Differential regulation of chordin expression domains in mutant zebrafish

Patterning along the dorsal-ventral (D-V) axis of Xenopus and Drosophila embryos is believed to occur through a conserved molecular mechanism, with homologous proteins Chordin and Short gastrulation (Sog) antagonizing signaling by bone morphogenetic protein 4 (BMP-4) and Decapentaplegic (Dpp), respectively. We have isolated a zebrafish gene that is highly homologous to chordin and sog within cysteine-rich domains and exhibits conserved aspects of expression and function. As in Xenopus embryos, zebrafish chordin is expressed in the organizer region and transiently in axial mesoderm. Injection of zebrafish chordin mRNA to the ventral side of Xenopus embryos induced secondary axes. Ectopic overexpression in zebrafish resulted in an expansion of paraxial mesoderm and neurectoderm at the expense of more lateral and ventral derivatives, producing a range of defects similar to those of dorsalized zebrafish mutants (Mullins et al., 1996). In accordance with the proposed function of chordin in D-V patterning, dorsalized zebrafish mutants showed expanded domains of chordin expression by midgastrulation, while some ventralized mutants had reduced expression; however, in all mutants examined, early organizer expression was unaltered. In contrast to Xenopus, zebrafish chordin is also expressed in paraxial mesoderm and ectoderm and in localized regions of the developing brain, suggesting that there are additional roles for chordin in zebrafish embryonic development. Surprisingly, paraxial mesodermal expression of chordin appeared unaltered in spadetail mutants that later lack trunk muscle (Kimmel et al., 1989), while axial mesodermal expression was affected. This finding reveals an unexpected function for spadetail in midline mesoderm and in differential regulation of chordin expression during gastrulation.