Cardiovascular responses and tolerance to an orthostatic stress were examined in eight men before and after eight months of endurance exercise training. Following training, maximal oxygen consumption and blood volume were increased, and resting heart rate reduced. Orthostatic tolerance was reduced following training in all eight subjects. It was concluded that prolonged endurance training decreased orthostatic tolerance and this decrease in tolerance appeared associated with attenuated baroreflex sensitivity and alterations in autonomic balance secondary to an increased parasympathetic tone noted with training.

The effects of the inhibitory neurotransmitters gammaamino butyric acid (GABA) and glycine were characterized on spontaneous activity recorded from mouse spinal cord cultures. The GABA concentration which completely inhibited burst activity was chosen as a quantifiable measure of culture drug response and was used to 1) assess interculture and intraculture variability, 2) determine the influence of culture age and initial activity on GABA responses, and 3) compare the GABA responses between networks obtained from whole spinal cord and ventral half spinal cord. Results showed that 1) no significant variability existed either within or among cultures, 2) the initial culture activity directly affected GABA responses, 3) the culture age had no effect on GABA responses, and 4) there was no significant difference in GABA responses between the two spinal cord tissues.

This research defines the morphological characteristics of the immune cells, coelomocytes, of the earthworm, Lumbricus terrestris. Such a definition of coelomocyte morphology can be correlated with immune function which will be of value in the development of a nonmammalian surrogate system to assess the immunotoxic potential of a terrestrial xenobiotics. Earthworms exposed to artificial soil dilutions of two complex xenobiotic mixtures, refuse derived fuel fly ash and a Superfund sire soil demonstrated an enhanced ability to produce hemolytic factors.

Aerobic Gram negative bacteria such as Pseudomonas putida were reported to possess class A ATCases and to have a M.W. of 360 kD. The nucleotide sequence of the P. putida pyrBC was determined to answer this question once and for all. The expected regulatory gene was not found. It is shown that the P. putida pyrB gene is overlapped by pyrC by 4 bp. The P.putida pyrB is 1005 bp (335 aa) in length and the pyrC is 1275 bp (425 aa) long. Both of these genes complement E. coli mutants with their respective genotypes. Another finding borne out from the sequence is an effector binding site at the N-terminus of pyrB of P. putIda. The binding site shows that effectors compete with carbamoylphosphate for the active site. In this dissertation, it is shown that the ATCase of P.putida is a trimer of M.W. of 109 kD (3 x 36.4 kD) and that the gene encoding pyrB is overlapped by the pyrC gene which encodes DHOase. It is also shown that the pyrBC encoded enzymes copurify as a dodecameric complex with a M.W. of 484 kD.

Three overlapping DNA fragments from the lower operon of Pseudomonas putida TOL plasmid pDK1, covering the xy1IH genes and downstream flanking region, were cloned into pUC19. They include a 2.8 kbp XhoI fragment, a 2.7 kbp PstI fragment and a 2.0 kbp EcoRI-HindIII fragment. They were subjected to DNA sequence analysis. The xy1I (4-oxalocrotonate decarboxylase) and xy1H (4-oxalocrotonate tautomerase) genes were found to possess coding regions of 792 and 189 nucleotides, respectively. A possible transcriptional terminator resembling E. coli rho-independent terminators was identified downstream of the translational stop of xy1H. An additional stem and loop structure was found in the intergenic region between xy1I and xy1H. The individual ORF's of the oxalocrotonate branch (xy1G, xy1I and xy1H) have been cloned into pUC18/19. The expression of the xy1G gene in E. coli was successfully assayed spectrophotometrically.

A novel bacterial expression system that is capable of producing high levels of soluble, stable, biologically active human vitamin D3 and estrogen receptors has been developed. The method utilizes ubiquitin fusion technology and a low temperature nalidixic acid induction of the lambda PL promoter. This system can produce large quantities of receptor antigen, but only a small fraction displays wild-type DNA and hormone binding properties. Therefore, the use of this system to overproduce receptors for crystallization studies is not practical. To overcome these problems, a 2 um based ubiquitin fusion system which allows regulated expression of the estrogen receptor in yeast (Saccharomyces cerevisiae) was developed. This system produces the estrogen receptor to a level of 0.2% of the total soluble protein. Moreover, this protein is undegradable, soluble, and biologically active. To test the transcriptional activity of the estrogen receptor produced in yeast, a cis-trans transcription assay was developed. This assay revealed that the transcriptional activity of the human estrogen receptor expressed in yeast was similar to that observed in transfected mammalian cells. This reconstituted estrogen transcription unit in Saccharomyces cerevisiae was utilized to examine the regulation of estrogen receptor functions by antiestrogens, to develop a random and rapid approach for …

Pseudomonas fluorescens NCIMB 11764 was capable of utilizing cyanide as a sole nitrogen source for growth. Cyanate (OCN") and S-cyanoalanine could also serve as nitrogenous substrates, but do not appear to play a role as intermediates in cyanide metabolism. Growth of this strain on cyanate as the sole nitrogen source led to the induction of an enzyme characterized as a cyanase (EC 3.5.5.3) based on its stoichiometric conversion of cyanate to ammonia, and dependence on bicarbonate for maximal activity. However, since cyanase activity was not elevated in cyanide-grown cells it was concluded that it serves no role in cyanide metabolism. Related studies aimed at examining a possible role for S-cyanoalanine as a cyanide-assimilation intermediate showed that while this compound also serves as a nitrogen source, it also is not important in cyanide metabolism. Studies focused on the utilization of free cyanide as a growth substrate led to the development of a fed-batch cultivation procedure greatly facilitating further experimentation aimed at the identification of cyanide metabolites. In addition to CO_2 and NH_3 as described earlier, two additional metabolites including formamide and formate were detected by using nC-NMR, HPLC, radioisotrapping methods and other analytical means. The formation of metabolites was shown to …

The host eosinophil response was compared in mice infected with either T. spiralis or T. pseudospiralis by determination of levels of splenic and intestinal phospholipase B, a marker enzyme for eosinophils. Primary infection of naive mice and challenge infection of homologously sensitized mice with T. pseudospiralis resulted in significantly lower tissue phospholipase B activities than infection with T. spiralis. Mice homologously challenged with T. pseudospiralis did exhibit an anamnestic eosinophil response compared to mice given a primary T. pseudospiralis infection. This anamnestic response, however, was significantly lower than the eosinophil response seen in sensitized mice given a homologous T. spiralis challenge. Mice sensitized to T. spiralis or T. pseudospiralis and heterologous challenge demonstrated an elevated eosinophil response compared to mice given a primary infection with either parasite. The heterologous challenge response, however, was not as intense as found for sensitized mice given a homologous challenge.

The chemical fate and biological impacts of cyfluthrin in aquatic ecosystems were investigated using microcosms (1.9 m^3 concrete tanks) during 1989. Results were compared to a concurrent pesticide registration study using mesocosms (634.7 m^3 earthen ponds). Ten spray drift and five soil runoff simulations were conducted. Pesticide loadings were scaled by system volume, with the same experimental design in ponds and microcosms. Aqueous cyfluthrin concentrations and sediment residue values were generally higher in microcosms, while aqueous half-life was shorter in the smaller systems.