Racial and other characteristics of human T cell leukemia/lymphoma (HTLV-I) and AIDS (HTLV-III) in Trinidad.

Adult T cell leukaemia/lymphoma was first recognised as a clinical entity in southwest Japan. Subsequently the Caribbean has been found to be another area where the disease is endemic, and sporadic cases have been identified in different parts of the world. The human T cell leukaemia/lymphoma virus (HTLV-I) is causally related to adult T cell leukaemia/lymphoma. A subgroup of HTLV, designated HTLV-III, has recently been isolated from many patients with the acquired immunodeficiency syndrome (AIDS) and preAIDS, and there is now evidence that this variant is the primary cause of AIDS. This is the first report from Trinidad to describe 12 cases of adult T cell leukaemia/lymphoma and 14 of AIDS. All were in patients of African descent. No cases were seen in subjects of East Indian descent, who, like those of African descent, comprise as much as 40% of the population. West Indians of African descent may have increased susceptibility to infection with both HTLV-I and HTLV-III.     

Nucleotide sequence encoding the biosynthetic dehydroquinase function of the penta-functional arom locus of Aspergillus nidulans.

The nucleotide sequence of a 1.9 Kb HindIII fragment of DNA derived from the arom locus of A.nidulans and encoding the biosynthetic dehydroquinase activity has been determined. The sequences encoding the biosynthetic and catabolic dehydroquinase enzymes of A.nidulans show no detectable homology, strongly suggesting convergent evolutionary pathways. The messenger RNA specified by the arom locus was detected as a 5.3 Kb RNA species.     

Trihydroxytetraenes: A novel series of compounds formed from arachidonic acid in human leukocytes

Addition of 15L-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) to human leukocytes led to the formation of a novel series of compounds containing four conjugated double bonds. The yield of tetraenes was increased approx. 100-fold when ionophore A23187 (5 μM) was added simultaneously with 15-HPETE. The structure of the major tetraene was established by physical methods as well as by chemical degradation and found to be 5,6,15L-trihydroxy-7,9,11,13-eicosatetraenoic acid.     

Prevention of stress-induced gastric ulcers by dopamine agonists in the rat

Dopamine (DA) and DA agonists have been shown to exert a protective role against the formation of duodenal ulcers. The effect of stimulation of DA receptors on the development of stress-induced gastric ulcers is currently unknown. Accordingly, we evaluated the effect of several DA agonists on the development of gastric ulcers induced by 3 h of cold + restraint stress (CRS) in rats. Apomorphine, d-amphetamine, methylphenidate, and threo-dl-p-hydroxymethylphenidate (an hydroxylated analog of methylphenidate), significantly reduced both the incidence and severity of CRS-induced gastric ulcers. The gastric cytoprotection afforded by these agents was dose-related, and completely antagonized by pretreatment with the peripheally acting DA antagonist domperidone. Because domperidone blocks peripheral, but not central, DA receptors, and since the entry of threo-dl-p-hydroxymethylphenidate across the blood-brain barrier into the brain is restricted to a great extent, we conclude that stimulation of peripheral DA receptors is primarily involved in the gastric cytoprotection induced by dopamimetics.The pathogenesis of stress-induced gastric ulcers remains largely unknown, and significant efforts have been made over the last decade to functionally characterize some of the factors involved in the etiology of this disease. Considerable attention has been focused on gastric acid secretion, but its primary role in stress-induced gastric ulcer disease remains uncertain. In fact, agents which effectively inhibit or neutralize gastric acid secretion such as cimetidine or antacids do not necessarily exert protection against stress-induced gastric ulcers (1,2). Moreover, in our original studies with neurotensin, a brain and gastrointestinal peptide, we have found that central administration of this neuropeptide, which completely prevents the development of cold + restraint stress (CRS)-induced gastric ulcers, does not appreciably alter gastric acid secretion (2). These findings support the contention that gastric acid secretion may not be an important factor in the development of this type of gastric ulcer.There is, however, considerable evidence that the automatic nervous system plays an intermediary role in the development of these ulcers (3,4). In this regard, surgical or pharmacological blockade of the vagal (cholinergic) division of the autonomic nervous system prevents the appearance of stress-associated gastric ulcers (5,6). Direct stimulation of catecholamine receptors, or indirect activation via increased sympathetic outflow to the periphery (7,4,8–11) appears to produce a salutary effect of stress-induced gastric ulcers.Szabo and his associates (12, 13, 14) have extensively studied the anti ulcer effects of dopamine (DA) in duodenal ulcer formation. Whether DA also modifies the development of stress-induced gastric ulcers is currently unknown.We have therefore evaluated the effect of selected DA receptor agonists and antagonists on CRS-induced gastric ulcer formation in rats.     

Identification of the coding region for the putidaredoxin reductase gene from the plasmid of Pseudomonas putida

The first 12 NH₂-terminal amino acids of the Pseudomonas putida putidaredoxin reductase were shown to be Met-Asn-Ala-Asn-Asp-Asn-Val-Val-Ile-Val-Gly-Thr. Comparison of these data with the DNA sequence of the BamHI-HindIII 197-base fragment derived from the PstI 2.2-kb fragment obtained from the P. putida plasmid showed that the putidaredoxin reductase gene was downstream from the cytochrome P-450 gene and the intergenic region had the 24-nucleotide sequence TAAACACATGGGAGTGCGTGCTAA. The Shine-Dalgarno sequence GGAG was detected in this region. The initiating triplet for the reductase gene was GTG, which normally codes for valine, but in the initiating codon position codes for methionine. From the amino acid sequence and X-ray data comparisons with other flavoproteins, what appears to be the AMP binding region of the FAD can be recognized in the NH₂-terminal portion of the reductase involving residues 5–35.     

Allelic variation at the frizzled locus of Drosophila

The epidermis of Drosophila has a tissue polarity that is manifested by a parallel array of polarized structures (primarily hairs and bristles). The production of normal tissue polarity requires the function of the frizzled (fz) locus. We have isolated a large number of alleles at this locus and have phenotypically characterized more than 25 of them. We have found extensive allelic variation that a previous study failed to detect. Most of the alleles fall into a hypomorphic to amorphic series. Two alleles, however, have unusual properties. These alleles, which in general are moderately strong alleles, fail to produce a rough eye phenotype that is characteristic of all the other moderate or strong fz alleles. Thus, these two alleles are tissue specific in effect. Furthermore, these two alleles also have a neomorphic or antimorphic effect on hair polarity in one region of the wing.     

Cell kinetics simulation languages

The use of stochastic simulation languages in cell kinetics research is discussed. Two special purpose simulation languages; CELLSIM and CELLGROW are described and example problems are presented.     

Physical mechanisms by which low-frequency magnetic fields can affect the distribution of counterions on cylindrical biological cell surfaces

Effects of dc and low-frequency ac magnetic fields on the motion and distribution of counterions on surfaces of cylindrical biological cells are examined. Magnetic fields along the cell axis as well as perpendicular to it are considered. When a dc magnetic field of any physically realizable magnitude is parallel to the cell axis it has no effect on ion motion, since the resulting Lorentz force is much smaller than the counterion-to-ion attractive force. However a dc magnetic field perpendicular to the cell surface will distort any preexisting ion motion and the resulting current (i) perpendicular to the original motion will be much larger than any current induced by a low-frequency ac magnetic field of the same magnitude as the dc field and parallel to it. Nevertheless i will still be much smaller than the current i_o constituting the original ion motion since (i/i_o)=/, where is the ion cyclotron frequency and the effective counterion collision frequency. With no preexisting coherent ion motion (i_o=0) the circulating current induced by a sinusoidally time-varying magnetic field parallel to the cell axis will be well below thermal fluctuation noise as long as only a single cell is considered; however when even an infinitesimal exchange of ions between adjacent cells is assumed the magnetic field will cause a redistribution of counterions on the cell surface. The resulting steady-state distribution becomes independent of the frequency of the applied magnetic field () when , where is 1/2 of the relaxation frequency for counterion diffusion. On the basis of these results it is suggested that whenever modification of cell behavior in response to application of a low-frequency magnetic field is established, measurements of dielectric permittivity versus frequency of the cell preparation be performed. Redistribution of counterions on the cell surface would be a likely cause if the noted effect becomes independent of the frequency of the applied magnetic field above the counterion dielectric relaxation frequency. It is also suggested that in magnetic field exposure of cell preparations the size of the sample (e.g. diameter of Petri dish) and direction of the magnetic field relative to average cell orientation can critically affect experimental results.     

Fungitoxic effects of nonprotein imino acids on growth of saprophytic fungi isolated from the leaf surface of Calliandra haematocephala

Four saprophytic and pathogenic fungi were isolated from the leaf surface of Calliandra haematocephala, a tropical legume known to contain large amounts of rare nonprotein imino acids in its leaves and seeds. The fungi Aspergillus niger, Aspergillus sp., Curvularia sp., and Penicillium sp. were cultured in the laboratory and tested for susceptibility to leaf extracts of the host plant and to proline, pipecolic acid, cis-5-hydroxypipecolic acid, and 2,4-trans-4,5-cis-4,5-dihydroxypipecolic acid. Fungal spore germination and germ tube growth were measured. Aspergillus sp. was inhibited by plant extracts and by pipecolic acid and cis-5-hydroxypipecolic acid. Curvularia sp. growth was stimulated by plant extracts and by pipecolic acid. The other two fungi were unaffected by any of the treatments. The data indicate that imino acids may play a role in the specific resistance of Calliandra spp. to Aspergillus sp.