Impaired splenic function and tuftsin deficiency in patients with intestinal failure on long term intravenous nutrition

Relatively little is known about the occurrence of neurocysticercosis in northeastern Brazil. There have been no published reports from the state of Ceará, but a review of the records at the Hospital S?o José in Fortaleza, Brazil identified 119 patients with neurocysticercosis diagnosed between January 1988 and April 1994. Patients came from 43 municipalities in Ceará. Their ages ranged from five to 74 years; the greatest number of cases were in persons 10-40 years of age; 63% were males. Seizures were the presenting complaint in 64% of the patients and headache in 22%. Two patients, each with several hundred intracranial lesions, presented with mental status changes; one was initially given the clinical diagnosis of viral meningoencephalitis. Computed tomography scans showed that 44% of the patients had five or more lesions. Cysts were found throughout the brain. The parietal lobe was the most frequent site of involvement; 85% of patients had one or more lesions there. The brain stem was involved in 8%. There was no consistent association between the severity of the clinical abnormalities and the radiologic findings. Computed tomography of the thighs was done in 10 persons; cysts were identified in nine.     

NMDA receptors mediate peripheral chemoreceptor afferent input in the conscious rat

N-methyl-D-aspartate (NMDA) glutamate receptors mediate critical components of cardiorespiratory control in anesthetized animals. The role of NMDA receptors in the ventilatory responses to peripheral and central chemoreceptor stimulation was investigated in conscious, freely behaving rats. Minute ventilation (VE) responses to 10% O2, 5% CO2, and increasing intravenous doses of sodium cyanide were measured in intact rats before and after intravenous administration of the NMDA receptor antagonist MK-801 (3 mg/kg). After MK-801, eupcapnic tidal volume (VT) decreased while frequency increased, resulting in a modest reduction in VE. Inspiratory time (TI) decreased, whereas expiratory time remained unchanged. The VE responses to hypercapnia were qualitatively similar in control and MK-801 conditions, with slight reductions in respiratory drive (VT/TI) after MK-801. In contrast, responses to hypoxia were markedly attenuated after MK-801 and were primarily due to reduced frequency changes, whereas VT was unaffected. Sodium cyanide doses associated with significant VE increases were 5 and 50 microg/kg before and after MK-801, respectively. Thus 1-log shift to the right of individual dose-response curves occurred with MK-801. Selective carotid body denervation reduced VE during hypoxia by 70%, and residual hypoxic ventilatory responses were abolished after MK-801. These findings suggest that, in conscious rats, carotid and other peripheral chemoreceptor-mediated hypoxic ventilatory responses are critically dependent on NMDA receptor activation and that NMDA receptor mechanisms are only modestly involved during hypercapnia.     

Clinical overview of occupational lung disease

The workplace has been a source of lung injury for centuries, yet awareness of the types of injuries has varied over time. Because of distinctive differences among the occupational lung disorders, a continual update of the clinical findings, dose response data, physiologic characteristics, and radiographic findings is needed. The radiologist plays a key role for the evaluation of miners, foundry or factory workers exposed to mineral dusts, and of workers exposed to the "biologic" dusts, infectious agents, cancer causing agents, and chemicals causing interstitial lung diseases. This overview includes a discussion of classification systems, criteria for diagnosis of occupational lung diseases, the pulmonary clinician's evaluation, and important aspects of specific disorders and concludes with a discussion of pulmonary disability determination.     

The effect of combined antenatal vitamin K and phenobarbital therapy on umbilical blood coagulation studies in infants less than 34 weeks' gestation

OBJECTIVE: To determine if antenatal vitamin K and phenobarbital therapy affect coagulation studies in umbilical blood at birth, and to provide 95% reference ranges for umbilical blood coagulation parameters in premature gestations. METHODS: Patients at imminent risk for spontaneous or indicated premature delivery less than 34 weeks' gestation were randomized to receive either placebo or vitamin K and phenobarbital. Prothrombin time (PT), activated partial thromboplastin time (PTT), functional coagulation factors, and decarboxylated prothrombin assays were performed on umbilical blood specimens. Decarboxylated prothrombin, also known as "protein induced by vitamin K absence-factor II" or precursor prothrombin, is a sensitive marker for vitamin K deficiency. Standardized values of PT and PTT are reported in seconds and standardized values of factor assays in percentage of normal adult functional activity (mean +/- one standard deviation). RESULTS: Newborns in the placebo and treatment groups had similar umbilical blood PT (12.6 +/- 1.2 versus 12.7 +/- 1.4 seconds), PTT (48.8 +/- 13.4 versus 49.6 +/- 13.8 seconds), and functional activity of factor II (40.3 +/- 12.5 versus 42.0 +/- 12.1%), factor VII (67.0 +/- 20.9 versus 66.8 +/- 18.9%), factor IX (27.4 +/- 12.8 versus 25.8 +/- 8.9%), and factor X (47.0 +/- 12.8 versus 49.2 +/- 11.6%). Newborns in the treatment group were about half as likely as those in the placebo group to have detectable decarboxylated prothrombin levels in umbilical blood at birth (gestational age-adjusted odds ratio 0.47, 95% confidence interval 0.22-1.01; P = .05). CONCLUSIONS: Combined maternal therapy with vitamin K and phenobarbital before premature delivery does not affect umbilical blood PT, PTT, or functional activity of vitamin K-dependent coagulation factors II, VII, IX, and X. However, it is associated with the reduced presence of decarboxylated prothrombin in umbilical blood at birth. There is significant improvement in umbilical blood coagulation tests as gestational age advances from 24 to 34 weeks.     

Solid-state 2H NMR study of methyl-d3-cobalamin

A solid-state 2H NMR study of methyl-d3-cobalamin has been performed as a function of temperature to provide information concerning the character and energetics of the motion performed by this unique bioorganometallic methyl group. Analysis of the 2H NMR line shape indicates that the methyl group undergoes rapid three-fold rotation, and that the Co-C-2H angle lies between 105.9 and 109.5 degrees. Determination of the spin-lattice relaxation times T1 shows that the relaxation is anisotropic, consistent with a "jumping" motion of the methyl group rather than rotational diffusion. This also provides the activation energy to methyl jumps as 8.3 +/- 1.3 kJ/mol. It is proposed that this energetic barrier may be a useful probe of changes in the electronic character of the Co-C bond that accompany the biological role of this molecule in such enzymes as methionine synthase.     

Immunomicroscopy: resin techniques and on-section labelling with immunocolloidal gold or immunoperoxidase--planning a protocol

On-section immunocytochemistry is divided into two parts: (i) processing of biological tissue for section microscopy and (ii) immunolabelling of sections. Many of the more successful microscopical methods employ delicate aldehyde fixation of biological tissue followed by "sympathetic" processing into an acrylic resin. Processing regimens do not have to be complicated. Simple and cost effective room temperature protocols utilising partial dehydration have been devised and they can be as effective as the more complex low temperature techniques in preserving both ultrastructure and antigenic reactivity. The embedded material can be investigated by either light or electron microscopy. Frozen sections can be cut and immunolabelled but only if the tissue is chemically fixed first, as in resin embedding. Fixation with low concentrations of aldehyde will normally better preserve tissue immunoreactivity but this may be at the expense of good ultrastructure with these protocols. If so, low temperature resin embedding methods or rapid freezing and cryosubstitution can be tried. The choice of processing protocol will determine which acrylic resin to use, as will the preference for subsequent immunolabelling with either colloidal gold or peroxidase/diaminobenzidine (DAB). Both types of labelling system offer advantages to localisation studies and can be used in combination for double or even triple labelling. Silver enhancement of the colloidal gold or DAB allows for improved observation by light microscopy.     

Gastric and biliary excretion of meperidine in man

The role and importance of enterogastric secretion in the disposition and elimination of the weak base, meperidine (pKa 8.63), was studied after intravenous administration (50 mg) of the drug to 6 normal volunteers. Continuous collection of the gastric fluid over a 4-hr period demonstrated the establishment of high gastric fluid/plasma concentration ratios for meperidine (mean about 50, range, 10 to 200). However, the total amount of drug recovered, even after correction for incomplete collection, was only a small percentage of the administered dose. Under basal conditions a mean +/- SE of 1.9 +/- 0.3 mg, equivalent to 3.7% of the administered dose, was found in the total gastric aspirate. Stimulation of gastric secretion by subcutaneous injection of betazole (1.5 mg/kg) increased this recovery to 3.6 +/- 0.3 mg (7.2%) primarily due to the increase in gastric volumen output. Aspiration of the gastric fluid in either the basal or stimulated situation had no observable effect upon the plasma concentration/time profile of meperidine whether assessed by the terminal half-life, t 1/2 beta, or the plasma clearance; control values were 3.8 +/- hr and 1,190 +/- 130 ml/min, respectively. In 2 subjects "bile fluid" was also collected for 2.5 hr and found to contain less than 0.2% of the administered dose. Enterosystemic recycling is therefore of minor importance in the disposition and elimination of meperidine in man.     

The heroin epidemic in San Francisco: estimates of incidence and prevalence

Much attention has recently been focused on the question of the extent of heroin use in America. In a worthwhile effort to call public attention to the problem, many estimates of its size have evidenced a tendency toward exaggeration and aggrandizement. This paper presents methods of estimation of the extent of heroin addiction which, when carefully employed, should effectively correct such distorted estimates. Two general types of estimation are employed, incidence and prevalence. Incidence estimates are concerned with new cases of heroin addiction that occur in a specific population within a given amount of time. These estimates are based upon self-report data from addicts regarding date of first addiction. When corrected for the "lag phase" (that period of time between onset of first addiction and eventual visit to a treatment program), these data permit accurate retrospective charting of incidence trends. Prevalence estimates focus on all known cases of heroin addiction in a specific population within a given amount of time. Three separate types of prevalence estimates from three separate sources are outlined in this article: estimates based on overdose death data, estimates based on crime statistics, and estimates of "unknown" addicts. In outlining these methods, this article describes the fluctuations in heroin addiction in one major American city, San Francisco, California. After analyzing data gathered from a sample of 2,367 addicts contacted over a 3-year period, this study suggests that the incidence of heroin addiction seems to have declined after 1970. Possible factors underlying this apparent decline in heroin addiction are then discussed, including the post-1970 maturation of the "population at risk," the effectiveness of antidrug media messages, the changing drug fashions in the heroin subculture, and the gradual deterioration of the quality and potency of street heroin.     

The limitations and potential of AVHRR GAC data for continental scale fire studies

Global Area Coverage (GAC) data from the Advanced Very High Resolution Radiometer (AVHRR) are available on a daily basis, dating back to July 1981. The AVHRR's 3·55–3·93 μm channel is suitable for detection of terrestrial hot spots, such as bushfires. The long-term archives and global cover make the GAC a potentially valuable data source for large scale fire studies. However, these data are sampled spatially through a combination of line skipping and averaging. This study shows that the sampling affects the sensitivity of GAC for fire detection in relation to ecosystem and season. The GAC are found to provide a reasonable measure of fire activity in grassland and open b'ush savannah, but to perform poorly in the forest margins. Overall at least 79 per cent of fires detected with non-sampled AVHRR data are missed by the GAC. This severely limits the use of GAC data for quantitative fire studies. The GAC does appear to provide a reasonable measure of fire calendar (i.e., variations in fire activity with time) and on a continental scale successfully identifies the main regions of fire activity. The potential of these data for continental scale fire studies is illustrated through the preliminary analysis of 277 GAC mosaics of Africa for the period September 1988 to August 1989.     

PRACTICAL INCONSISTENCY MANAGEMENT FOR CRITICAL-TASKS DECISION-SUPPORT SYSTEMS

Abstract

In this paper, the problem of logical consistency in critical-tasks decision systems is addressed. It is shown how local search techniques can be used to check the (in)consistency of very large propositional knowledge bases (KBs). Using new heuristic findings. we can now implement efficient forms of diagnostic reasoning in the context of very large ICBs modeling deep models of complex devices and including patterns of default reasoning.