Early Release Science of the exoplanet WASP-39b with JWST NIRCam

Measuring the metallicity and carbon-to-oxygen (C/O) ratio in exoplanet atmospheres is a fundamental step towards constraining the dominant chemical processes at work and, if in equilibrium, revealing planet formation histories. Transmission spectroscopy (for example, refs. 1,2) provides the necessary means by constraining the abundances of oxygen- and carbon-bearing species; however, this requires broad wavelength coverage, moderate spectral resolution and high precision, which, together, are not achievable with previous observatories. Now that JWST has commenced science operations, we are able to observe exoplanets at previously uncharted wavelengths and spectral resolutions. Here we report time-series observations of the transiting exoplanet WASP-39b using JWST's Near InfraRed Camera (NIRCam). The long-wavelength spectroscopic and short-wavelength photometric light curves span 2.0-4.0 micrometres, exhibit minimal systematics and reveal well defined molecular absorption features in the planet's spectrum. Specifically, we detect gaseous water in the atmosphere and place an upper limit on the abundance of methane. The otherwise prominent carbon dioxide feature at 2.8 micrometres is largely masked by water. The best-fit chemical equilibrium models favour an atmospheric metallicity of 1-100-times solar (that is, an enrichment of elements heavier than helium relative to the Sun) and a substellar C/O ratio. The inferred high metallicity and low C/O ratio may indicate significant accretion of solid materials during planet formation (for example, refs. 3,4,) or disequilibrium processes in the upper atmosphere (for example, refs. 5,6).

Early Release Science of the exoplanet WASP-39b with JWST NIRSpec G395H

Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking the formation and evolution of exoplanetary systems1,2. Access to the chemical inventory of an exoplanet requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based3-5 and high-resolution ground-based6-8 facilities. Here we report the medium-resolution (R ≈ 600) transmission spectrum of an exoplanet atmosphere between 3 and 5 μm covering several absorption features for the Saturn-mass exoplanet WASP-39b (ref. 9), obtained with the Near Infrared Spectrograph (NIRSpec) G395H grating of JWST. Our observations achieve 1.46 times photon precision, providing an average transit depth uncertainty of 221 ppm per spectroscopic bin, and present minimal impacts from systematic effects. We detect significant absorption from CO2 (28.5σ) and H2O (21.5σ), and identify SO2 as the source of absorption at 4.1 μm (4.8σ). Best-fit atmospheric models range between 3 and 10 times solar metallicity, with sub-solar to solar C/O ratios. These results, including the detection of SO2, underscore the importance of characterizing the chemistry in exoplanet atmospheres and showcase NIRSpec G395H as an excellent mode for time-series observations over this critical wavelength range10.

Protein requirement of patients on CAPD: A study on nitrogen balance

This work was presented in part at the 12th Annual Contractor's Conference of the National Institutes of Arthritis, Metabolism and Digestive Diseases, Bethesda, USA, January 15, 1979 and the Congress of the International Society for Artificial Internal Organs at the symposium on CAPD, New York Hilton, New York, April 19, 1979.

Studies on Amino Acids in Diabetic Patients Undergoing Capd

Studies in patients with uremia due to diabetes mellitus treated with CAPD show that the kinetics of amino acid equilibration between dialysate and plasma behave differently from those in patients with uremia of different etiology. Diabetics also have larger amino acid losses in dialysate.

COMT Genetic Reduction Produces Sexually Divergent Effects on Cortical Anatomy and Working Memory in Mice and Humans

Genetic variations in catechol-O-methyltransferase (COMT) that modulate cortical dopamine have been associated with pleiotropic behavioral effects in humans and mice. Recent data suggest that some of these effects may vary among sexes. However, the specific brain substrates underlying COMT sexual dimorphisms remain unknown. Here, we report that genetically driven reduction in COMT enzyme activity increased cortical thickness in the prefrontal cortex (PFC) and postero-parieto-temporal cortex of male, but not female adult mice and humans. Dichotomous changes in PFC cytoarchitecture were also observed: reduced COMT increased a measure of neuronal density in males, while reducing it in female mice. Consistent with the neuroanatomical findings, COMT-dependent sex-specific morphological brain changes were paralleled by divergent effects on PFC-dependent working memory in both mice and humans. These findings emphasize a specific sex-gene interaction that can modulate brain morphological substrates with influence on behavioral outcomes in healthy subjects and, potentially, in neuropsychiatric populations.

Neuroimaging evidence of major morpho-anatomical and functional abnormalities in the BTBR T+TF/J mouse model of autism

BTBR T+tf/J (BTBR) mice display prominent behavioural deficits analogous to the defining symptoms of autism, a feature that has prompted a widespread use of the model in preclinical autism research. Because neuro-behavioural traits are described with respect to reference populations, multiple investigators have examined and described the behaviour of BTBR mice against that exhibited by C57BL/6J (B6), a mouse line characterised by high sociability and low self-grooming. In an attempt to probe the translational relevance of this comparison for autism research, we used Magnetic Resonance Imaging (MRI) to map in both strain multiple morpho-anatomical and functional neuroimaging readouts that have been extensively used in patient populations. Diffusion tensor tractography confirmed previous reports of callosal agenesis and lack of hippocampal commissure in BTBR mice, and revealed a concomitant rostro-caudal reorganisation of major cortical white matter bundles. Intact inter-hemispheric tracts were found in the anterior commissure, ventro-medial thalamus, and in a strain-specific white matter formation located above the third ventricle. BTBR also exhibited decreased fronto-cortical, occipital and thalamic gray matter volume and widespread reductions in cortical thickness with respect to control B6 mice. Foci of increased gray matter volume and thickness were observed in the medial prefrontal and insular cortex. Mapping of resting-state brain activity using cerebral blood volume weighted fMRI revealed reduced cortico-thalamic function together with foci of increased activity in the hypothalamus and dorsal hippocampus of BTBR mice. Collectively, our results show pronounced functional and structural abnormalities in the brain of BTBR mice with respect to control B6 mice. The large and widespread white and gray matter abnormalities observed do not appear to be representative of the neuroanatomical alterations typically observed in autistic patients. The presence of reduced fronto-cortical metabolism is of potential translational relevance, as this feature recapitulates previously-reported clinical observations.

The epidemiology of life-threatening complications associated with reproductive process in public hospitals in Argentina

OBJECTIVE

To analyse life-threatening obstetric complications that occurred in public hospitals in Argentina.

DESIGN

Multicentre collaborative cross-sectional study.

SETTING

Twenty-five hospitals included in the Perinatal Network of Buenos Aires Metropolitan Area.

POPULATION

Women giving birth in participating hospitals during a 1-year period.

METHODS

All cases of severe maternal morbidity (SMM) and maternal mortality (MM) during pregnancy (including miscarriage and induced abortion), labour and puerperium were included. Data were collected prospectively.

MAIN OUTCOME MEASURES

Identification criteria, main causes and incidence of SMM; case-fatality rates, morbidity-mortality index and effective intervention's use rate.

RESULTS

A total of 552 women with life-threatening conditions were identified: 518 with SMM, 34 with MM. Identification criteria for SMM were case-management (48.9%), organ dysfunction (15.2%) and mixed criteria (35.9%). Incidence of SMM was 0.8% (95% confidence interval [95% CI] 0.73-0.87%) and hospital maternal death ratio was 52.3 per 100 000 live births (95% CI 35.5-69.1). Main causes of MM were abortion complications and puerperal sepsis; main causes of SMM were postpartum haemorrhage and hypertension. Overall case-fatality rate was 6.2% (95% CI 4.4-8.6): the highest due to sepsis (14.8%) and abortion complications (13.3%). Morbidity-mortality index was 15:1 (95% CI 7.5-30.8). Use rate of known effective interventions to prevent or treat main causes of MM and SMM was 52.3% (95% CI 46.9-57.7).

CONCLUSIONS

This study describes the importance of life-threatening obstetric complications that took place in public hospitals with comprehensive obstetric care and the low utilisation of known effective interventions that may decrease rates of SMM and MM. It also provides arguments that justify the need to develop a surveillance system for SMM.

[Prevalence of the bacteria causing diarrea in a Rosario Hospital, Argentina]

Bacterial agents causing diarrea in patients attended in a hospital of Rosario, Argentina. The frequency of bacterial agents causing diarrhea can vary in patients of different areas, and through the time. In an epidemiological surveillance we studied 304 patients with diarrheal diseases looking for Salmonella enterica, Shigella spp, Campylobacter spp, Aeromonas spp, Yersinia enterocolitica, and diarrheogenic Escherichia coli. C. jejuni was isolated in 30 patients (9,9 %), Salmonella in 18 (5,9 %), and enteropathogenic E. coli (EPEC) in 7 (2,3 %). Most cases due ton C. jejuni had mucus and/or blood in their feces. Unexpectedly we didn't fine any cases due to Shigella spp. There was much less cases due to EPEC than in our previous studies, and occurred only in children of less than 5 years old. It is necesary to take in consideration that C. jejuni cause nearly all the cases of diarrhea in patients with mucus and blood in their feces actually in our region.

Clinical and genetic studies in hereditary spastic paraplegia with thin corpus callosum

BACKGROUND

A complicated form of recessive hereditary spastic paraplegias (HSPs) with thin corpus callosum (TCC) was first described in Japan, and most of the Japanese families showed linkage to chromosome 15q13-15. A recessive HSP locus (SPG11) has also been mapped to chromosome 15q13-15 in Italian and North American families with and without TCC, and it overlaps the region identified in the Japanese families.

OBJECTIVE

To study clinically and genetically 12 Italian families with HSP and TCC.

METHODS

The authors investigated 18 affected and 30 healthy individuals from 12 unrelated Italian families with recessive HSP-TCC. Clinical, neurophysiologic, and neuroradiologic studies were undertaken. All patients were negative for SPG7 mutations. Genetic linkage analyses were carried out with polymorphic DNA markers on 15q13-15.

RESULTS

Five families were consistent with linkage, thus defining a 19.8-cM region between markers D15S1007 and D15S978, encompassing the SPG11 interval. In one consanguineous family, linkage could be firmly excluded, confirming genetic heterogeneity. Two families appeared not linked to the region, but this could not be firmly proved because of the small family size. The remaining four families were uninformative for linkage purposes.

CONCLUSION

HSP-TCC is common in Italy. The phenotype is fairly homogeneous and is associated with impaired cognition. There are at least two loci for HSP-TCC, one of which is on chromosome 15q13-15.

SPG3A: An additional family carrying a new atlastin mutation

The authors report on a novel frameshift mutation (c.1688insA) in the SPG3A gene resulting in premature translation termination of the gene product atlastin. These data add a new variant to the second disease gene in autosomal dominant hereditary spastic paraplegia (ADHSP) and lend definitive support to its causative role. By combining direct testing of SPAST and SPG3A, at least 50% of ADHSP families can now receive appropriate genetic diagnosis.

Glutathione in blood of patients with Friedreich's ataxia

BACKGROUND

Oxidative stress and mitochondrial dysfunction have long been considered to play a role in Friedreich's ataxia, a neurodegenerative disease due to a GAA expansion in a gene coding for a mitochondrial protein (frataxin), implicated in the regulation of iron metabolism. Since glutathione is an important antioxidant whose role has been recently proposed in the pathogenesis of some neurodegenerative diseases, we investigated glutathione metabolism in the blood of 14 patients with Friedreich's ataxia by measuring total, free and protein-bound glutathione concentrations.

MATERIALS AND METHODS

Blood samples were obtained from 14 unrelated patients with Friedreich's ataxia (nine males, five females) and 20 age-matched healthy controls (10 males, 10 females). Total and free glutathione concentrations were determined by reverse-phase liquid chromatography with fluorescence detection; the glutathionyl-haemoglobin separation from healthy and pathological subjects was obtained by electrospray ionization-mass spectrometry.

RESULTS

We consistently found a reduction of free glutathione levels (0.55 +/- 0.06 nmol mg(-1) haemoglobin, vs. 8.4 +/- 1.79 nmol mg(-1) haemoglobin, P < 0.001) in the blood of patients with Friedreich's ataxia, a total glutathione concentration comparable to the controls (15 +/- 2.6 nmol mg(-1) haemoglobin, vs. 15.4 +/- 1.4 nmol mg(-1) haemoglobin), and a significant increase of glutathione bound to haemoglobin (15 +/- 1.5 vs. 8 +/- 1.8%, P < 0.05) in erythrocytes.

CONCLUSIONS

Our findings give evidence of an impairment in vivo of glutathione homeostasis in Friedreich's ataxia, suggesting a relevant role of free radical cytotoxicity in the pathophysiology of the disease; this study may also prove useful in the search for an oxidative stress marker in neurodegeneration.

Mitochondrial myopathy, parkinsonism, and multiple mtDNA deletions in a Sephardic Jewish family

The authors describe a family of Sephardic Jews with progressive external ophthalmoparesis, skeletal muscle weakness, and parkinsonism. Autosomal recessive inheritance was suggested by many consanguineous marriages, although a dominant disorder could not be excluded. No linkage to known progressive external ophthalmoparesis locus was found. The presence of cytochrome c oxidase-negative ragged-red fibers, biochemically reduced respiratory chain complexes, and multiple mitochondrial DNA deletions in muscle biopsies from four patients suggested a new mitochondrial disorder of intergenomic communication.

Effects of valsartan on left ventricular diastolic function in patients with mild or moderate essential hypertension: comparison with enalapril

OBJECTIVE

This study compares the effects of an AT1 angiotensin II receptor antagonist (valsartan) with those of an ACE inhibitor (enalapril) on left ventricular (LV) diastolic function in patients with mild or moderate essential hypertension and no evidence of LV hypertrophy at echocardiography.

METHODS

A total of 24 patients (16 men, mean age 47 +/- 8 years) underwent radionuclide ambulatory monitoring (Vest) of LV function at rest and during upright bicycle exercise testing before and after two 4-week treatment periods with valsartan (80-160 mg/day orally) and enalapril (20-40 mg/day orally) according to a double-blind, crossover randomization scheme.

RESULTS

In the overall population no differences between the two treatments were found in LV peak filling rate (PFR) either at rest or at peak exercise. In a subgroup analysis it was found that baseline PFR was normal (= 2.5 EDV/sec) in 12 patients (subgroup A) and impaired (< 2.5 EDV/sec) in the remaining 12 (subgroup B). In both subgroups, valsartan and enalapril induced a significant and comparable reduction of systolic and diastolic blood pressure. In subgroup A, valsartan and enalapril did not induce significant changes in PFR. In subgroup B, valsartan increased PFR both at rest (from 2.0 +/- 0.3 to 2.4 +/- 0.3 EDV/sec, P < 0.01) and at peak exercise (from 4.1 +/- 1.1 to 4.4 +/- 1.0 EDV/s, P < 0.05), whereas enalapril did not change PFR either at rest (2.0 +/- 0.4 EDV/s, P < 0.01 versus valsartan) or at peak exercise (3.7 +/- 1.1 EDV/sec, P < 0.05 versus valsartan).

CONCLUSIONS

Valsartan-induced renin-angiotensin system blockade is able to improve LV filling in patients with mild or moderate essential hypertension and impaired diastolic function. These findings support the hypothesis of a contribution of the renin-angiotensin system in the control of LV diastolic function in these patients.

[Computerized follow-up cards for ambulatory patients with implanted pacemaker or defibrillator]

The follow up of pacemaker and defibrillator dependent patients has a significant role for both the evaluation of pacing effectiveness and check of hemodynamic advantages about patient's quality of life. The bulky paper archives are often inaccurate, hampering the consultation. At present the paper card is the only document which can be utilized to record some data concerning the implant and patient clinical story. Therefore, there is the necessity for a card that can include all patient's data, and the implant and programming pacemaker/defibrillator data during follow up. This new pacemaker card has portable file or data-base including shared data with safety mechanism, which can be utilized in several controls by different users (physicians, hospital ward, primary care units, insurance companies). The pacemaker card includes a chip that permits to store a considerable amount of data; it can be update in every further medical control, in observance of laws. The card Chip Operating System (C.O.S.) consists of a microchip with a memory completely managed by the operating system inside the chip itself. The card can be read by means of a GCR-200 modem linked with a PC IBM-compatible computer and the data can be updated during the follow up. The pacemaker-defibrillator card will appear immediately on screen, and it can be printed, updated and/or modified by a Microsoft Windows operating programme. With this pacemaker card we are able to ensure serviceable medical work, particularly in terms of cost/benefit ratio giving to patient more and more reasoning and safe service.

Role of catheter-induced mechanical trauma in localization of target sites of radiofrequency ablation in automatic atrial tachycardia

OBJECTIVES

We compared the efficacy of two different mapping techniques in identifying the ablation site for atrial tachycardia. Moreover, we evaluated the additive positive predictive value of mechanical interruption of atrial tachycardia to reduce the number of ineffective radiofrequency applications.

BACKGROUND

Radiofrequency catheter ablation has been suggested as a highly effective technique to treat drug-resistant atrial tachycardia. However, irrespective of the mapping technique utilized, success was most often achieved with a large number of radiofrequency applications.

METHODS

Forty-five patients with atrial tachycardia underwent radiofrequency catheter ablation. Mapping techniques included identification of earliest atrial activation and pace-mapping concordant sequence.

RESULTS

Atrial tachycardia was successfully treated in 42 (93.3%) of 45 patients with a mean of 3.9 radiofrequency pulses/patient. An interval between the onset of the intracavitary atrial deflection and the onset of the P wave during atrial tachycardia (AP interval) > or = 30 ms (p < 0.001) and pace-mapping concordant sequence (p = 0.01) were all significant predictors of outcome. An AP interval > or = 30 ms and a pace-mapping concordant sequence were highly sensitive (92.8%, 95% confidence interval [CI] 80.5% to 98.5%; 85.7%, 95% CI 71.5% to 94.6%, respectively) but less specific (47.8%, 95% CI 37.9% to 58.2%, 36.8%, 95% CI 27.6% to 47.2%, respectively) in identifying the site of ablation. By using atrial tachycardia mechanical interruption combined with the AP interval >30 ms or the pace-mapping concordant sequence, we obtained a specifically of 76.5% (95% CI 66.4% to 84.0%) and 73.5% (95% CI 63.2% to 81.4%), respectively, and a positive predictive value of 49.2% and 44.6%, respectively.

CONCLUSIONS

An AP interval > or = 30 ms and a pace-mapping concordant sequence were reliable mapping features for predicting the outcome of the ablation procedure. Mechanical interruption of atrial tachycardia improved the specificity and positive predictive value of these two mapping techniques.

Stability of temperature asymmetries in reflex sympathetic dystrophy over time and changes in pain

OBJECTIVE

To determine the clinical usefulness of skin temperature patterns for tracking reflex sympathetic dystrophy (RSD) by assessing (a) long-term relationships between changes in pain due to RSD and patterns of near surface blood flow and (b) relationships between site of pain and site of greatest asymmetries in near surface blood flow patterns.

DESIGN

Multiple videothermographic evaluations of near surface blood flow patterns were performed on subjects diagnosed as having RSD. At each session, subjects filled in an outline of the body to show the location, intensity, and description of their pain. The thermograms were evaluated independently by two raters for location and intensity of pain, as well as location and degree of temperature asymmetries.

SETTING

Two Army Medical Centers.

SUBJECTS

Thirteen male and 16 female subjects were subsequently diagnosed as having RSD.

OUTCOME MEASURES

Ratings of pain and videothermograms of the lower limbs were used as outcome measures.

RESULTS

All but one subject were usually cooler on the most painful side by at least 0.5 degrees C. The amount of relative coolness was not proportional to pain intensity. There were no consistent overlaps between exact location of pain and greatest thermal asymmetry. Seven subjects were thermally symmetrical on at least one recording. Six subjects were warmer on the affected side on at least one recording. One subject was always warmer on the affected side.

CONCLUSIONS

Videothermography is not an appropriate tool to use alone for either single session diagnosis or multi-session tracking of RSD.

Endotracheal tube misplacement: incidence, risk factors, and impact of a quality improvement program

To assess the impact of a quality improvement program on the occurrence of serious complications related to endotracheal tube misplacement and to identify risk factors, we did a before and after comparison in the adult intensive care units of a military referral hospital. All adult patients requiring endotracheal intubation during two 12-month periods comprised the study population. After the identification of a sentinel case, a retrospective review identified 278 adult patients requiring endotracheal intubation over a 12-month period. Twenty-two of these patients had at least one significant endotracheal tube misplacement; five of these misplacements (23%) were associated with serious complications (anoxic encephalopathy, atelectasis and respiratory failure, gastric aspiration, pneumothorax, and hypoxemia). In four of these patients the complications directly contributed to patient morbidity and mortality. During a subsequent 12-month period, after the initiation of a quality improvement program, 246 patients requiring tracheal intubation were prospectively studied. Of these 246 patients, 113 (46%) were identified as having at least one endotracheal tube misplacement requiring immediate repositioning. The incidence of serious complications related to endotracheal tube misplacement was significantly less during the implementation of the quality improvement program (0 of 246 patients) than during the retrospective period (5 of 278 patients). Multivariate analysis showed that a longer duration of endotracheal intubation, the lack of chemical paralysis, and the occurrence of cardiac arrest were independently predictive of endotracheal tube misplacement. These results suggest that a specific ICU quality improvement program can have a favorable impact on patient outcome.

[Anaerobic threshold in the evaluation of heart function in patients with rate-responsive pacemaker]

It is very difficult to evaluate the ability of carrying out physical exercise in patients with rate responsive (RR) pacemaker (PM). However, the anaerobic threshold (AT) proved to be a useful parameter in the evaluation of cardiac function. The AT can be easily reproduced and not influenced from emotional aspects of both the patient and the physician, moreover being under maximum and then easy to achieve. Aims of our study were: to evaluate if the cardiopulmonary stress test can represent a method to be used for a more correct rate responsive pacemaker programming; to compare the data obtained of 3 rate responsive pacemakers steered by different sensors. We have studied 24 patients, of whom 10 with Activitrax (A), 8 with Meta (M), and 6 with Phymos MPT (P) pacemakers. Patients were submitted to symptoms limited cycloergometer stress test at 2 different settings: fixed rate at 70 b/min; increasing rate at until 85% of maximum heart rate for each patient, with range 0 + 10 W/min. Gas exchange data were continuously collected using an automated system (Medical Graphic System 2001) based on Whipp and Wasserman's method.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on amino acids in diabetic patients undergoing CAPD

Studies in patients with uremia due to diabetes mellitus treated with CAPD show that the kinetics of amino acid equilibration between dialysate and plasma behave differently from those in patients with uremia of different etiology. Diabetics also have larger amino acid losses in dialysate.

Kinetics of amino acids equilibration in the dialysate during CAPD

The equilibrium between plasma and peritoneal dialysis fluid has been studies for 23 amino acids during peritoneal exchanges at dwell times up to 8 hours in patients on CAPD. It is demonstrated that equilibration is a particular process typical for each amino acid which after 8 hour is nearly complete only for Glycine, Alanine and Asparagine.

Amino acid losses during CAPD

Amino acid losses in peritoneal dialyzate during CAPD were less than 2 g a day (15, 128 micrometers). CAPD does not correct the tyrosine/phenylalanine ratio in plasma and does not prevent accumulation of 3-methylhistidine.

Protein requirement of patients on CAPD: a study on nitrogen balance

Nitrogen balance studies were performed in 8 patients undergoing CAPD. Patients were studied in a metabolic ward for 14 days while eating a diet providing 1.2 g/kg B.W. of proteins and supplying 166-188 KG/Kg. From these studies it is concluded that 1.2 g/Kg are a safe intake for patients on CAPD. Nevertheless it is strongly suggested that patients on CAPD should undergo a nitrogen balance study in order to ascertain whether such a diet is safe or should be modified for energy and/or protein supply.

Stability of peritoneal urea clearance in continuous ambulatory peritoneal dialysis (18 months experience with CAPD)

A group of 13 patients on Continous Ambulatory Peritoneal Dialysis up to 18 months was studied. During the study period, Peritoneal Urea Clearance was stable. In all but 2 cases peritonitis did not depress the efficiency in clearing urea. When Peritoneal Urea Clearance was corrected for 1.73 m2 surface area, there was on the average an 11.8% increase over not corrected clearance rates. This increase was statistically significant.

CBF changes after (-)eburnamonine infusion in patients with cerebrovascular insufficiency

The authors have made a study of CBF after (-)eburnamonine infusion, during angiographic examination of 6 patients with cerebrovascular insufficiency, for a hemodynamic evaluation of the drug efficacy on CBF. The measurement of CBF was done by 133Xe according to the method of Lassen and Ingvar. A correlation between clinical findings, angiographic findings and CBF changes was done to state the employment of (-)eburnamonine in patients with cerebrovascular insufficiency.