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.     

Measurements on a Dynamic A-B Phase Boundary in Superfluid 3He at Very Low Temperatures

We present preliminary measurements of the dynamics of a moving A-B phase interface in superfluid ³ He at temperatures below 0.2T _c We initially stabilise the interface at low temperatures with a shaped magnetic field. We can then move the interface in a controlled manner by applying small additional time-dependent fields. The interface is created inside a quasiparticle radiator consisting of a cylindrical chamber in weak thermal contact with the refrigerant. Vibrating wire resonators inside the radiator allow us to monitor the temperature of the superfluid and to infer the heat generated by the interface motion. When we oscillate the interface at low frequencies, we measure spectacular oscillatory swings of the liquid temperature arising from the enormous change in the low lying density of states as the volume of the A-phase superfluid is alternately compressed and expanded. We have also observed hysteresis in the transition as a function of magnetic field. In particular, we observe a small history-dependent super-magnetisation of the B-phase prior to A-phase nucleation in the experimental chamber. When the system is in the metastable super-magnetised state we are able to observe a higher nucleation probability of the A-phase when the cryostat is exposed to neutrons.     

3-Methyl-α-himachalene: Proposed structure for novel homosesquiterpene sex pheromone ofLutzomyia longipalpis (diptera: Psychodidae) from Jacobina,Brazil

The principal behaviorally active volatile component (ca. 90% +) of the sex pheromone glands ofLutzomyia longipalpis from Jacobina. Brazil, has been isolated and characterized as a novel homosesquiterpene with the structure 3-methyl--himachalene (C₁₆H₂₆). A minor component (ca. 10%) of the gland extract has also been identified as the sesquiterpene-himachalene (C₁₅H₂₄). This work confirms that there are at least 3 members of theL. longipalpis species complex.     

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.     

Meso-modelling of Non-Crimp Fabric composites for coupled drape and failure analysis

To date macro-analysis methods have been invariably used to analyse textile composite structures for forming and mechanical performance. Techniques such as geometric ‘mapping’ for the draping of textile fabrics and classical laminate analysis combined with simplified failure criteria to determine mechanical performance have formed the basis of most of these methods. The limited accuracy of the physical laws applied is appropriate to macro-analysis methods in which the fibre-matrix composite is treated as homogeneous medium. Today, however, modern high performance computers are opening new possibilities for composites analysis in which far greater detail of the composite constituent materials may be made. This paper presents Finite Elements techniques for the draping simulation of textile composites, specifically biaxial Non Crimp Fabrics, in which the complex deformation mechanisms of the dry tows and stitching may be properly modelled at the individual tow and stitch meso-level. The resulting ‘deformed’ Finite Element model is then used to provide a basis for accurate simulation of the impregnated composite structure. The modelling techniques for both draping and structural analysis are present, together with validation results for the study of a relatively large-scale hemisphere composite part.