Chemical dependency and drug testing in the workplace.

Urine testing for drug use in the workplace is now widespread, with the prevalence of positive drug tests in the work force being 0% to 15%. The prevalence of marijuana use is highest, and this can be reliably tested. Though it is prudent to rid the workplace of drug use, there is little scientific study on the relationship of drug use and workplace outcomes, such as productivity and safety. Probable-cause testing and preemployment testing are the most common applications. Random testing has been less accepted owing to its higher costs, unresolved legal issues, and predictably poor test reliability. Legal issues have focused on the right to policy, discrimination, and the lack of due process. The legal cornerstone of a good program is a policy that is planned and agreed on by both labor and management, which serves both as a contract and as a procedure in which expectations and consequences are known. The National Institute on Drug Abuse is certifying laboratories doing employee drug testing. Testing methods when done correctly are less prone to error than in the past, but screening tests can be defeated by adulterants. Although the incidence of false-positive results is low, such tests are less reliable when the prevalence of drug abuse is also low.     

Characterisation of Pseudomonas rhamnolipids

The Gram negative organism, Pseudomonas aeruginosa, is often found in the lungs of patients with cystic fibrosis and other forms of severe bronchiectasis, where it secretes a number of extracellular toxins including the mono- and dirhamnolipids. The principal monorhamnolipid from P. aeruginosa has previously been identified as rhamnosyl-3-hydroxydecanoyl-3-hydroxydecanoate (Rh-C10.C10). A number of related mono- and dirhamnolipids have been purified from cultures of a clinical isolate of P. aeruginosa and identified by fast atom bombardment and electron impact mass spectrometry: these contain the 3-hydroxyoctanoyl-3-hydroxydecanoate (C8.C10) and 3-hydroxydecanoyl-3-hydroxydodecanoate (C10.C12) homologues. Structural isomers were also present where the order of the lipid linkage was transposed (Rh-C10.C8 and Rh-C12.C10). Unsaturated mono- and dirhamnolipids containing the 3-hydroxydecanoyl-3-hydroxydodec-5-enoate (C10.C12:1) lipid were also present.     

Stimulation of CTP: phosphocholine cytidylyltransferase and phosphatidylcholine synthesis by incubation of rat hepatocytes with phospholipase A2

The effect of phospholipase A2 treatment of rat hepatocytes on CTP: phosphocholine cytidylyltransferase and phosphatidylcholine synthesis was investigated. Cytidylyltransferase is recovered from the cytosol and in a membrane-bound form with the microsomes. Digitonin treatment of cells causes rapid release into the medium of the cytosolic, but not the microsomal form of the cytidylyltransferase. Incubation of hepatocytes for 10 min with phospholipase A2 (0.9 units/dish) in the medium, resulted in a 33% decrease in the cytidylyltransferase activity released by digitonin treatment (2.5 +/- 0.15 nmol/min per mg compared to 3.9 +/- 0.10 nmol/min per mg in the control). In agreement with the digitonin experiments, incubation with 0.9 units/dish of phospholipase A2 resulted in a decrease in the cytidylyltransferase activity in the cytosol (from 4.3 +/- 0.10 nmol/min per mg to 2.6 +/- 0.14 nmol/min per mg) and a corresponding increase in the microsomal fraction (from 0.9 +/- 0.16 nmol/min per mg to 1.8 +/- 0.20 nmol/min per mg). The effect of phospholipase A2 on cytidylyltransferase translocation was concentration- and time-dependent. Incubation of hepatocytes in the presence of phospholipase A2 (0.9 units/dish) for 10 min prior to pulse-chase experiments resulted in an increase in radiolabel incorporation into phosphatidylcholine (from 2.4 +/- 0.02.10(-5) dpm/dish to 3.1 +/- 0.1.10(-5) dpm/dish) and a corresponding decrease in radiolabel associated with the choline (from 2.5 +/- 0.05.10(-5) to 1.4 +/- 0.03.10(-5) dpm) and phosphocholine fractions (from 8.5 +/- 0.07.10(-5) to 6.9 +/- 0.05.10(-5) dpm). We conclude that phospholipase A2 can cause a stimulation of CTP: phosphocholine cytidylyltransferase activity and phosphatidylcholine synthesis in cultured rat hepatocytes.     

Cross-linkage sites in type I collagen fibrils studied by neutron diffraction

Cross-links in tendon collagen are essential for the biomechanical strength of healthy tissue. The nature and position of these cross-links has long been a subject for conjecture. We have approached this problem in a non-destructive manner, by studying neutron diffraction from collagen fibrils that have been specifically deuterated by reduction at keto-amine and Schiff base groups with sodium borodeuteride (NaB2H4). The intensities of the first 23 meridional reflections were recorded for both native and reduced tendons. These data were used to calculate the neutron-scattering density profile of the 67 nm (D) repeat of type I collagen fibrils in rat tail tendon. This approach not only succeeds in determining the location of the cross-linkage sites with respect to the fibril structure, as projected onto the fibre axis, but also presents a novel form of the isomorphous derivative solution to the phase problem.     

Fusaric acid and other metabolite production in Fusarium oxysporum f. sp. vasinfectum

A thin layer chromatography system is described for the analysis of fusaric acid and other secondary metabolites, to assist in the identification of pathogenic races of Fusarium oxysporum f. sp. vasinfectum . There were differences in the metabolite profiles of the races grown on different media.     

Neurophysins as markers of vasopressin and oxytocin release. A study in carcinoma of the lung

Vasopressin-neurophysin (hNpI), oxytocin-neurophysin (hNpII) and blood osmolality were assayed before any treatment in basal conditions in 35 patients suffering from lung carcinoma (20 oat cell, 6 undifferentiated and 9 well-differentiated epidermoid cell carcinomas). Plasma vasopressin (antidiuretic hormone, ADH) was also assayed in 7 of the 20 patients suffering from oat cell carcinoma. We found a close correlation (r = 0.98) between plasma ADH and hNpI levels in the 7 patients. Further, hNpI was elevated in 13 out of the 20 oat cell carcinoma patients and in none of the epidermoid-cell carcinoma group; however, searching for an abnormality of ADH secretion as reflected by a detectable plasma hNpI level together with subnormal plasma osmolality revealed 2 additional positive results in the oat cell carcinoma group, and 2 out of the 6 in the undifferentiated-cell carcinoma group. hNpII was increased together with an increase in hNpI in 6 oat cell carcinoma patients; it was specifically increased without hNpI increment in 2 additional oat cell carcinoma patients and in 2 patients of the undifferentiated-cell carcinoma group (different from the 2 positive for the hNpI-osmolality ratio). hNpI and hNpII were normal in the majority of undifferentiated and all of the differentiated epidermoid-cell carcinoma group. Hence, our results show that simultaneous measurements of hNpI, hNpII, and blood osmolality could detect abnormalities in 17 out of 20 oat cell carcinoma patients, in 4 of the 9 undifferentiated-cell carcinoma patients, but in none of the differentiated epidermoid-cell carcinoma patients, suggesting that the neurophysin assay can be used for the early detection of oat cell- and possibly other neuroendocrine-derived carcinomas.     

An ultrastructural analysis of the dispersed cell phase during development of the annual fish,Cynolebias

Cell ultrastructure was investigated during the dispersion phase of development in the annual fish Cynolebias. Three cellular populations encompass the yolk mass during dispersion, namely, 1) the yolk syncytial layer (YSL) or periblast, which lies directly over the surface of the yolk; 2) the deep blastomeres of the blastoderm, which engage in morphogenetic movements on the surface of the YSL and beneath the enveloping layer prior to forming the future embryo; and 3) the enveloping layer (EVL) of the blastoderm, which is a cohesive epithelium that forms the outermost cell layer of the blastoderm. Deep blastomeres contain numerous mitochondria and scattered glycogen rosettes that appear to function in the utilization of energy reserves. These cells also possess surface extensions such as filopodia and ruffles. Numerous microfilaments running parallel to the plasma membrane occur in cell extensions and in the cortical cytoplasm of neighboring blastomeres. In bleb-like extensions such as ruffles, microfilamentous stress fibers run parallel to the plane of the plasma membrane and prevent cellular organelles from entering the hyaline cap of the ruffle. Deep blastomeres also have basal projections that contain glycogen as well as pits in the basal membrane. Blastomeres move about using the YSL as a substrate. The YSL possesses specializations for nutrient uptake, storage, and transport such as numerous multivesicular bodies and large amounts of glycogen. Glycogen, in the rosette form, occurs in extraordinary amounts, virtually occluding the cytoplasm. Glycogen reserves are postulated to serve as an energy source during diapause. Glycogen is sometimes contained within villous projections that extend from the apical surface of the YSL. This configuration suggests the possibility of glycogen transport to the overlying deep blastomeres. Specializations of the EVL include apical tight junctions and basal lateral zonulae adherentes that interdigitate with those of adjacent EVL cells. The EVL serves as an impermeable membrane that protects the developing egg from the vicissitudes of its environment.     

Phylogenetic analysis and secondary structure of the Bacillus subtilis bacteriophage RNA required for DNA packaging

An unusual RNA molecule encoded by the Bacillus subtilis bacteriophage phi 29 is a structural component of the viral prohead and is required for the ATP-dependent packaging of DNA. Here we report a model of secondary structure for this prohead RNA developed from a phylogenetic analysis of the primary sequences of prohead RNAs of related phages. Twenty-nine phages related to phi 29 were found to produce prohead RNAs. These RNAs were analyzed by their ability to replace phi 29 RNA in in vitro phage assembly, by Northern blot hybridization with a probe complementary to phi 29 RNA, and by partial and complete sequence analyses. These analyses revealed four quite different sequences ranging in length from 161 to 174 residues. The secondary structure deduced from these sequences, in agreement with earlier observations, indicated that prohead RNA is organized into two domains. The larger 5'-domain (Domain I) is composed of 113-117 residues and contains four helices. Three of these helices appear to be organized into a central stem that is interrupted by two unpaired loops and the fourth helix and loop. The smaller 3'-domain (Domain II) is composed of 40-44 residues and consists of two helices. Domains I and II are separated by 8-13 unpaired residues. Nuclease cleavage occurs readily in this single-stranded joining region, and this cleavage allows the subsequent separation of the two RNA domains. The separated Domain I is fully active in DNA packaging in vitro. The functional significance and biological role of Domain II are unknown. The phylogenetic secondary structure model provides a basis for further analysis of the role of this RNA in bacteriophage morphogenesis.