Neuropsychological impairment from acute low-level exposure to carbon monoxide

OBJECTIVE: To investigate the effects of acute low-level exposure to carbon monoxide on higher cognitive functions in healthy humans. DESIGN: An empirical study of the effects of low-level exposure to carbon monoxide on higher cognitive functions in young healthy volunteers and a matched nonexposed control group. SETTING: A dormitory at the Hebrew University campus in Jerusalem, Israel. PARTICIPANTS: Forty-five student volunteers who were exposed to carbon monoxide from residential kerosene stoves for 1.5 to 2.5 hours (air carbon monoxide concentrations of 17-100 ppm; mean +/- SD, 61 +/- 24 ppm) served as the experimental group and 47 nonexposed students served as the control group. MAIN OUTCOME MEASURES: A battery of neuropsychological tests was administered to each participant including digit span, the revised Wechsler Memory Scale for verbal and figural memory, Trail-Making Test parts A and B, digit symbol, block design, and the Rey Auditory Verbal Learning Test. RESULTS: Venous blood carboxyhemoglobin (Hbco) levels in participants of the study group ranged from 0.01 to 0.11 (mean +/- SD, 0.04 +/- 0.03) and correlated with air carbon monoxide concentrations (r = 0.39; P = .01). The experimental group scored significantly lower than controls on the following tests: digit span forward (P = .02), short-term (P = .008) and long-term semantic memory (P = .008), digit symbol (P = .004), block design (P = .009), recall of figural memory (P = .02), and Trail-Making part A (P = .04). No significant differences were found between the experimental and control groups in other tests. CONCLUSIONS: The lower scores on neuropsychological tests indicate dysfunctions in memory, new learning ability, attention and concentration, tracking skills, visuomotor skills, abstract thinking, and visuospatial planing and processing. These dysfunctions correspond with previous reports of carbon monoxide neurotoxic effects in patients with moderate carbon monoxide poisoning. Low-level exposure to carbon monoxide results in impairment of higher cognitive functions. Neuropsychological testing appears to be sensitive in the detection of subtle neurologic dysfunctions resulting from carbon monoxide poisoning.     

The ethical allocation of scarce resources in surgery: implants and cost

This paper is a discussion of the factors involved in instituting a bulk purchasing program for surgical supplies. An improved understanding of the surgical procedure of joint arthroplasty must relate to the variability in surgical methods that achieve patient outcomes. An understanding of the outcomes in relation to the expected duration of the success of an implant and the high costs associated with a revision earlier than expected must be factored into the budget and costs of implants. The ethical implications of choosing one implant over another are considered. A more uniform outcome assessment with respect to surgical activities is needed and potential savings related to other operating-room costs must be examined. Optimizing the implant to patient requirements is the goal within the framework of current fiscal constraints.     

Physiological and mechanical adaptations of rabbit medial collateral ligament after anterior cruciate ligament transection

Progressive physiological and mechanical changes in the medial collateral ligament of the adult rabbit were investigated for as long as 48 weeks after disruption of the anterior cruciate ligament. Eighty-one New Zealand White rabbits were separated into experimental, sham-operated control, and normal control groups. The experimental group underwent unilateral transection of the right anterior cruciate ligament, sham-operated animals served as controls for comparison, and normal animals were evaluated as age-matched, undisturbed (no surgery) controls. Blood flow to the medial collateral ligament (as a physiological measure) and mechanical function (structural and material properties) were assessed at 6, 14, and 48 weeks. The results indicated that loss of the anterior cruciate ligament leads to early mechanical deterioration of the medial collateral ligament with a corresponding loss of physiological homeostasis. Six to 14 weeks after the transection, values for cross-sectional area of the medial collateral ligaments rapidly increased to 1.5 times control values. The ligament became twice as large as the control ligament by 48 weeks. Concomitantly, medial collateral ligament stress at failure of the medial collateral ligament complex decreased rapidly 6-14 weeks after the transection and eventually fell to one-half that of controls by 48 weeks. In terms of low-load behaviour, laxity and load relaxation were significantly greater than that of controls 6 weeks after transection and were further increased by 14 weeks. By 48 weeks, laxity values had recovered somewhat and load-relaxation measures had recovered to near control values. At both 6 and 14 weeks, a statistically significant elevation in blood flow was demonstrated compared with controls. By 48 weeks, however, blood flow was no different from that of the sham-operated control. Thus, early after transection of the anterior cruciate ligament, both low-load and high-load mechanical properties of the medial collateral ligament deteriorated and the rate of blood flow was temporarily elevated. By 48 weeks, blood flow declined to near control values, with a corresponding recovery in viscoelastic behaviour. These findings suggest that, after transection of the anterior cruciate ligament, viscoelastic behaviour of the medial collateral ligament may be related to changes in blood flow and that restoration of normal flow patterns and vascular responses may be linked to the recovery of some low-load mechanical properties in the anterior cruciate ligament-deficient medial collateral ligament.     

The onset of schizophrenia

This survey deals with findings and results of systematic clinical-psychiatric and -psychological studies of the true onset of schizophrenia and its significance. Many symptoms precede the psychotic onset of schizophrenia. These have been described by Huber as 'basic symptoms', who developed the concept of basic stages and basic symptoms gradually since the 1950's. The basic symptoms are experiential and not behavioral in kind and only recognizable by the self-reports of the patients. They are rateable using a structural scale (Bonn Schedule for the Assessment of Basic Symptoms: BSABS) described below. They form the two precursor syndromes: (1) prodromes lead on average within 3.3 years to a psychotic episode; and (2) outpost syndromes that are completely remitting on average within 5 months and precede the first psychotic episode on average 10 years. Basic symptoms can be further divided into level 1 (non-specific) and level 2 (characteristic) basic symptoms. Basic symptoms, positive and negative symptoms have to be differentiated; they also develop in this chronological sequence: first non-specific, then characteristic basic symptoms, followed on average many years later by positive symptoms, and, finally by negative symptoms. Structured ratings of the basic symptoms and their recognition in the precursor syndromes enables physicians to detect early symptoms of a schizophrenic illness that, if treated at this stage, can lead to a better long-term outcome.     

Modulation of myocardial economy and efficiency in mammalian failing and non-failing myocardium by calcium channel activation and beta-adrenergic stimulation

OBJECTIVE: We investigated the energy-metabolic consequences of positive inotropic stimulation by the calcium channel activator, BAY K 8644, in comparison with isoprenaline, focussing both on the economy of force development and the efficiency of external work. METHODS: In the first instance, heat liberation was measured in isometrically contracting right ventricular papillary muscles from guinea pigs by means of antimony-bismuth thermopiles; in the second instance, external work and myocardial oxygen consumption were analyzed in isolated failing and non-failing working rat hearts. RESULTS: In the guinea pig muscle strip preparations BAY K 8644 (10(-5) M) and isoprenaline (10(-8 M) increased peak developed force from 13.7 +/- 2.7 to 37.6 +/- 14.9 mN/mm2 and from 13.6 +/- 5.2 to 38.8 +/- 3.3 mN/mm2, respectively (P < 0.01). Stress-time integral was increased from 10.3 +/- 3.0 to 34.7 +/- 19.2 mN.s/mm2 by BAY K 8644 and from 9.5 +/- 2.4 to 23.0 +/- 1.6 mN.s/mm2 by isoprenaline. Whereas a significant decrease in the ratio between stress-time integral and initial heat (integral of Pdt/IH) (i.e., economy contraction) was observed for isoprenaline (5.26 +/- 1.91 before and 3.11 +/- 0.72 N.m.s.J-1 after treatment (P < 0.01), BAY K 8644 did not significantly alter this index (5.26 +/- 2.39 before and 6.22 +/- 2.63 N.m.s.J-1 after treatment). Similar results were obtained for the ratio between stress-time integral and tension-dependent heat. Significantly more calcium ions were required for equieffective activation of the contractile proteins with isoprenaline as compared to BAY K 8644. In working preparations of sham-operated and infarcted rat hearts, the increase in myocardial oxygen consumption per minute (delta MVO2) for a given increase in external work per minute (delta P) was significantly higher with isoprenaline than with equipotent concentrations of BAY K 8644 or high calcium. CONCLUSIONS: Inotropic mycardial stimulation by BAY K 8644 is associated with higher economy and efficiency than stimulation by isoprenaline when analyzed both by heat measurements in isometric preparations and by myocardial oxygen consumption in working heart preparations.     

Texture modelling applications

The paper describes a technique by which realistic textures can be constructed from a statistical model. It further tells us, in principle, how to map the texture onto a surface of any shape, maintaining consistency and scaling, without producing repeating patterns. It describes how a method designed earlier for grey scales alone can be extended to the colour case. The generalization of the former work to macroscopic textures is also presented. An application of this method to the Design is finally shown.     

Glucose-induced sequential processing of a glycosyl-phosphatidylinositol-anchored ectoprotein in Saccharomyces cerevisiae

Transfer of spheroplasts from the yeast Saccharomyces cerevisiae to glucose leads to the activation of an endogenous (glycosyl)-phosphatidylinositol-specific phospholipase C ([G]PI-PLC), which cleaves the anchor of at least one glycosyl-phosphatidylinositol (GPI)-anchored protein, the cyclic AMP (cAMP)-binding ectoprotein Gce1p (G. Müller and W. Bandlow, J. Cell Biol. 122:325-336, 1993). Analyses of the turnover of two constituents of the anchor, myo-inositol and ethanolamine, relative to the protein label as well as separation of the two differently processed versions of Gce1p by isoelectric focusing in spheroplasts demonstrate the glucose-induced conversion of amphiphilic Gce1p first into a lipolytically cleaved hydrophilic intermediate, which is then processed into another hydrophilic version lacking both myo-inositol and ethanolamine. When incubated with unlabeled spheroplasts, the lipolytically cleaved intermediate prepared in vitro is converted into the version lacking all anchor constituents, whereby the anchor glycan is apparently removed as a whole. The secondary cleavage ensues independently of the carbon source, attributing the key role in glucose-induced anchor processing to the endogenous (G)PI-PLC. The secondary processing of the lipolytically cleaved intermediate of Gce1p at the plasma membrane is correlated with the emergence of a covalently linked high-molecular-weight form of a cAMP-binding protein at the cell wall. This protein lacks anchor components, and its protein moiety appears to be identical with double-processed Gce1p detectable at the plasma membrane in spheroplasts. The data suggest that glucose-induced double processing of GPI anchors represents part of a mechanism of regulated cell wall expression of proteins in yeast cells.     

Thermal conductivity of the new refrigerants R134a,R152a,and R123 measured by the transient hot-wire method

Thermal-conductivity measurements are reported for the new refrigerants R134a, R152a und R123. Transient hot-wire experiments were performed which cover both the liquid and vapor states at temperatures and pressures ranging from?=?20°C to 90°C and fromp=0.1 bar to 60 bar respectively. The results are correlated with density and temperature. In addition temperature dependent correlations are presented for (i) saturated liquid, (ii) saturated vapor, (iii) ideal gas (which equals approximately vapor state at ambient pressure). Finally the results are compared with data from the literature and also with the thermal conductivities of R12 and R11.     

Computer-aided manufacture of three-dimensional objects by laser space-resolved photopolymerization

The local absorption of the light of suitable energy can lead to the polymerization of a liquid monomer. By moving the incident laser beam, one can create objects of very fine quality. This idea is the basis for the computer-aided manufacture of three-dimensional objects.