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Biomedical subjects

E L Martin

Publications and source records attributed to E L Martin.

At least 19 recordsLinked to original sources
PubMed2002

Growth, carcass characteristics, muscle conjugated linoleic acid (CLA) content, and response to intravenous glucose challenge in high percentage Wagyu, Wagyu x Limousin, and Limousin steers fed sunflower oil-containing diet.

The effect of breed and diet on insulin response to glucose challenge and its relation to intramuscular fat deposition was determined in 36 steers with 12 each of greater than 87% Wagyu (referred to as Wagyu), Wagyu x Limousin, and Limousin breeds. Weaned steers were blocked by weight into heavy, medium, and light calves and placed in six pens with two pens per weight type and with two steers of each breed per pen. Three pens with steers from each weightclass were fed backgrounding and finishing diets for 259 d, while the other three pens were fed the same diets where 6% of the barley grain was replaced with sunflower oil. Prior to initiation of the finishing phase of the study the intravenous glucose tolerance test (VGTIT) was conducted in all steers. Once steers were judged as carrying adequate 12th-rib fat, based on weight and days on feed, they were harvested and graded and samples of the longissimus muscle were procured for determination of fat content and fatty acid composition. Dietary oil improved (P = 0.011; 0.06) ADG and feed conversion efficiency of steers during the latter part of backgrounding and only ADG during early part ofthe finishing period. Generally percent kidney, pelvic, and heart fat was the only adiposity assessment increased (P = 0.003) by dietary oil. The IVGTT results indicated that insulin response to intravenous glucose was lower in Limousin steers than in Wagyu steers. Dietary oil decreased (P = 0.052) fasting plasma insulin concentration in Wagyu steers compared with Limousin steers. The correlation coefficients among the IVGTT measures and intramuscular fat content or marbling score were less than 0.4, and only a negative trend existed between fasting insulin and USDA marbling scores. However, the carcasses of the Wagyu steers graded US Choice, and 66% of the Wagyu carcasses graded US Prime, which were substantially better than the quality grades obtained for the carcasses from the other breed types. Dietary oil did not affect muscle fat content but increased (P = 0.01) conjugated linoleic acid (CLA) concentrations by 339%. Results indicated that IVGTT measures were not appropriate indices of marbling potential in cattle and that dietary oil can enhance CLA content of beef.

Adipose Tissue↗
PubMed2001

Evidence for a mesodermal embryonic regulator of the sea urchin CyIIa gene.

The CyIIa gene of the sea urchin embryo is a model for study of cis-regulation downstream of cell-type specification, as CyIIa transcription follows the specification and initial differentiation of the embryonic domains in which it is expressed. These are the skeletogenic and secondary mesenchyme and gut. We carried out a detailed structural and functional analysis of a cis-regulatory region of this gene, extending 780 bp upstream and 125 bp downstream of the transcription start site, that had been shown earlier to reproduce faithfully the complex and dynamic CyIIa pattern of expression. This analysis revealed that the overall pattern of expression of the CyIIa gene appears to be governed mainly by two independent sets of DNA elements, which are target sites for specific proteins present in blastula-stage nuclear extract. One type of element, which controls a dynamic program of expression in both skeletogenic and secondary mesenchyme cells, contains the consensus-binding site for a member of the ets transcription factor family. The other, which is responsible for the terminal or permanent phase of CyIIa expression in the gut, shares homologies with the late module of the endoderm-specific Endo16 gene (endo16 Module B). Oligonucleotides containing replicas of these two target sites fused upstream of a sea urchin basal promoter are sufficient to confer accurate mesenchyme and late gut expression of an injected GFP construct. The finding of a single protein target site that recapitulates CyIIa expression in both primary and secondary mesenchyme cells suggests the existence of a pan-mesodermal gene expression program in the sea urchin embryo.

Actins↗
PubMed2001

Adenine toxicity and transport in the moderately halophilic eubacterium Halomonas elongata.

The presence of adenine in the L-alanine defined medium substantially inhibited the growth of the moderately halophilic eubacterium Halomonas elongata. Extensive attempts to reverse the adenine toxicity for growth were made using a variety of purine and pyrimidine compounds, vitamins, and amino acids. Of the compounds tested, only cytosine was found to reverse the adenine growth inhibition. This indicates a mechanism similar to that found for some strains of Escherichia coli in which the presence of exogenous purines (e.g. adenine) was found to stop purine de novo synthesis and repress the synthesis of the pyrimidine salvage enzyme cytosine deaminase. H. elongata was found to possess an active adenine uptake system that was sodium dependent with only lithium having a considerable capacity to replace the sodium. A competition study indicated that the adenine transport system was quite specific. This paper represents the initial study of purine and pyrimidine salvage pathways and adenine uptake for the moderately halophilic eubacteria.

Adenine↗
PubMed2000

Influence of infected cell growth state on bacteriophage reactivation levels.

Reactivation of UV-C-inactivated Pseudomonas aeruginosa bacteriophages D3C3, F116, G101, and UNL-1 was quantified in host cells infected during the exponential phase, during the stationary phase, and after starvation (1 day, 1 and 5 weeks) under conditions designed to detect dark repair and photoreactivation. Our experiments revealed that while the photoreactivation capacity of stationary-phase or starved cells remained about the same as that of exponential-phase cells, in some cases their capacity to support dark repair of UV-inactivated bacteriophages increased over 10-fold. This enhanced reactivation capacity was correlated with the ca. 30-fold-greater UV-C resistance of P. aeruginosa host cells that were in the stationary phase or exposed to starvation conditions prior to irradiation. The dark repair capacity of P. aeruginosa cells that were infected while they were starved for prolonged periods depended on the bacteriophage examined. For bacteriophage D3C3 this dark repair capacity declined with prolonged starvation, while for bacteriophage G101 the dark repair capacity continued to increase when cells were starved for 24 h or 1 week prior to infection. For G101, the reactivation potentials were 16-, 18-, 10-, and 3-fold at starvation intervals of 1 day, 1 week, 5 weeks, and 1. 5 years, respectively. Exclusive use of exponential-phase cells to quantify bacteriophage reactivation should detect only a fraction of the true phage reactivation potential.

Adenosine Triphosphatases↗
PubMed2000

The effects of ultraviolet radiation on the moderate halophile Halomonas elongata and the extreme halophile Halobacterium salinarum.

Both the moderately halophilic bacterium, Halomonas elongata, and the extremely halophilic archaea, Halobacterium salinarum, can be found in hypersaline environments (e.g., salterns). On complex media, H. elongata grows over a salt range of 0.05-5.2 M, whereas, H. salinarum multiplies over a salt range of 2.5-5.2 M. The purpose of this study was to illustrate the effect that solar (UV-A and UV-B) and germicidal radiation (UV-C) had on the growth patterns of these bacteria at varied salt concentrations. Halomonas elongata grown on a complex medium at 0.05, 1.37, and 4.3 M NaCl was found to be more sensitive to UV-A and UV-B radiation, as the salt concentration of the medium increased. Halobacterium salinarum grown on a complex medium at 3.0 and 4.3 M NaCl did not show a significant drop in viability after 39.3 kJ.m-2 of UV-A and UV-B exposure. When exposed to UV-C, H. elongata exhibited substantially more sensitivity than H. salinarum. In H. elongata, differential sensitivity to UV-C was observed. At 0.05 M NaCl, H. elongata was less sensitive to UV-C than at 1.37 and 4.3 M NaCl. Both bacteria showed some photoreactivation when incubated under visible light following both UV-A, UV-B, and UV-C exposure. Mutagenesis following UV-C exposure was demonstrated by both organisms.

Anti-Bacterial Agents↗
PubMed1999

Characterization of Pseudomonas aeruginosa bacteriophage UNL-1, a bacterial virus with a novel UV-A-inducible DNA damage reactivation phenotype.

UNL-1, a lytic virus of Pseudomonas aeruginosa, was observed to express a novel inducible DNA damage reactivation activity in UV-A-irradiated P. aeruginosa host cells. The expression of bacteriophage reactivation was quantified in hosts exposed to either UV-C or UV-A radiation. While reactivation of UV-C-damaged UNL-1 was not inducible in UV-C-irradiated host cells, an approximately 13-fold induction was observed in UV-A-irradiated host cells. When host cells were exposed to sunlight, reactivation of damaged UNL-1 virus increased eightfold. The UV-A induction of UNL-1 DNA damage reactivation was supported in hosts lacking recA gene function. This report is the first description of a recA-independent, UV-inducible virus DNA damage repair system. Our findings suggest that a combination of both host and virus DNA repair processes contribute to the persistence and sustained replication of some bacterial viruses in aquatic environments.

Base Composition↗
PubMed1999

Distance estimation with night vision goggles: a little feedback goes a long way.

Immediate feedback was given to correct observers' estimates of distance in an experiment in which those estimates were made outdoors at night while observers wore night vision goggles (NVGs). Initially observers made unguided estimates of distances between marked positions in an open field. Those distances ranged from 7.6 m (25 ft) to 64 m (210 ft). Later the same observers made more estimates. After each of these they were told the measured distance between the positions. During this training, the observers' height from the ground plane was either at a standing position or at an elevated position raised 2.3 m (7 ft 7 in) from standing position. After the training--either immediately after, a week later, or at both times--observers made unguided estimates of distance for a second time. These latter estimates of ground distance made with the NVGs were improved. Average improvement of the observers' estimates persisted for at least one week after training. This training can be applied to improve clearance estimates and estimates of hover height for pilots of rotary-wing aircraft.

Aerospace Medicine↗
PubMed1998

Cis-regulation downstream of cell type specification: a single compact element controls the complex expression of the CyIIa gene in sea urchin embryos.

CyIIa, a cytoskeletal actin gene of Strongylocentrotus purpuratus, is expressed specifically though transiently in the embryonic skeletogenic and secondary mesenchyme and, later in development, is permanently activated in the hindgut and midgut. CyIIa transcription follows, and is therefore downstream of, the initial specification of these embryonic domains. A detailed functional analysis of the cis-regulatory system governing the rate and the location of CyIIa expression during development was carried out using GFP expression constructs. About 4.4 kb of CyIIa sequence including a leader intron were examined for cis-regulatory function. Distal elements scattered over several kb account for 60% of the quantitative output of the expression construct and a strong amplifier of expression is located within the leader intron. However, the complex spatial pattern of CyIIa expression is completely reproduced by a compact upstream regulatory element <450 bp in length. We found no evidence anywhere in the 4.4 kb sequence examined for negative regulators required to repress ectopic expression. The specific site that mediates CyIIa expression in the midgut in late embryos and larvae was identified. This site is the same as that necessary and sufficient for midgut expression of the Endo16 gene late in development, and was shown to bind the same transcription factor. Except for some temporal and quantitative features, the S. purpuratus expression construct is expressed accurately and specifically in the same diverse cell types when introduced into embryos of Lytechinus pictus, which belongs to a different echinoid order. No ectopic expression was observed, in contrast to the result of a similar interspecific gene transfer experiment carried out earlier on a different cytoskeletal actin gene that is expressed much earlier in development. Presentation of the set of transcription factors that activate CyIIa in the differentiated cells in which it is expressed is apparently a conserved feature of these cell types.

Actins↗
PubMed1996

Potent peptide analogues of a G protein receptor-binding region obtained with a combinatorial library.

The C terminus of the G protein alpha subunit represents an important site of interaction between heterotrimeric G proteins and their cognate receptors. We have screened a combinatorial peptide library based on the C terminus of the alpha subunit of Gt (340-350) and have identified unique sequences that bind rhodopsin with high affinity. Six of these sequences, as both fusion proteins and synthetic peptides, were significantly more potent than the parent sequence in binding to and stabilization of metarhodopsin II. These sequences provide information about which residues are required for appropriate receptor interaction. We observed that in all the high affinity sequences, a positively charged residue at position 341 was changed to a neutral one. Thus, it appears that the receptor-G protein interaction was designed to be low affinity to ensure efficient catalysis of G protein activation. We also observed Cys-347 and Gly-348 to be invariant, and hydrophobic residues were always located at positions 340, 344, 349, and 350, demonstrating the critical nature of these residues. A composite of the structures of the high affinity sequences was modeled based upon the structure of rhodopsin-bound trNOESY NMR of this region of Gt alpha (Dratz, E. D., Fursteneau, J. E., Lambert, C. G., Thireault, D. L., Rarick, H., Schepers, T., Pakhlevaniants, S., and Hamm, H. E. (1993) Nature 363, 276-280) and provides insight into the complementary G protein-binding surface of the receptor.

Amino Acid Sequence↗
PubMed1995

Peptides which bind to E-selectin and block neutrophil adhesion.

E-selectin is an inducible cell adhesion molecule which mediates rolling of neutrophils on the endothelium, an early event in the development of an inflammatory response. Inhibition of selectin-mediated rolling is a possible means for controlling inflammation-induced diseases, and several classes of compounds have been tested for this use. We describe here the use of recombinant peptide library screening for identification and optimization of novel ligands which bind to E-selectin. Several of these peptides bind with Kd values in the low nanomolar range and block E-selectin-mediated adhesion of neutrophils in static and flow-cell assays. Administration of the peptide to mice undergoing an acute inflammatory response reduced the extent of neutrophil transmigration to the site of inflammation, demonstrating the utility of this compound as a potential therapeutic. The identification of a peptide ligand for E-selectin suggests that the complete natural ligand for this adhesion molecule may include protein as well as carbohydrate moieties.

Amino Acid Sequence↗
PubMed1992

Persistent müllerian duct syndrome with transverse testicular ectopia and spermatogenesis.

Normal male sexual differentiation is dependent on at least 2 factors: 1) testosterone and 2) müllerian inhibiting factor. The absence of müllerian inhibiting factor is responsible for a rare form of male pseudohermaphroditism, the persistent müllerian duct syndrome or hernia uteri inguinale. Patients with this syndrome present with persistent müllerian structures and the syndrome may be associated with transverse testicular ectopia. Additionally, most patients have azoospermia. We report a case of persistent müllerian duct syndrome with transverse testicular ectopia in which sperm are documented in the ejaculate.

Adult↗
PubMed1988

Speech recognition by a deaf-blind multichannel cochlear implant patient.

A case study of the first deaf-blind patient implanted with a Nucleus 22 channel cochlear prosthesis is presented. The patient's preimplant evaluation data, using a powerful hearing aid and vibro-tactile device, are compared with results obtained 8 months postimplant. Preimplant testing indicated no consistent response to sound. Postimplant testing showed ability to comprehend some open set speech with hearing alone through the cochlear implant including ability to utilize the telephone without a code system. The postimplant data suggest potential benefit for other postlingually deaf-blind individuals from multichannel cochlear stimulation.

Blindness↗
PubMed1987

Optimization of bovine satellite cell-derived myotube formation in vitro.

Post-natal myogenic satellite cells, isolated from the sternomandibularis muscles of bovine at slaughter were used for primary culture studies. Isolated satellite cells tended to differentiate into multinucleated myotubes more efficiently if initially plated on to a fibronectin substratum. Bovine-derived satellite cells displayed greater fused cell numbers when exposed to Dulbecco's Modified Eagle's Medium (DMEM) supplemented with horse serum than similar supplementation with fetal calf serum (P less than 0.05) or sheep serum (P less than 0.05). In addition, differentiation appeared nearly complete after 4 days exposure to DMEM-1% horse serum as verified by beta-D-arabinofuranosyl-cytosine addition to cultures. Collectively, these data provide the first evidence that satellite cells can be isolated from a bovine skeletal muscle. Furthermore, these data indicate that bovine-derived satellite cells can be induced to undergo substantial morphological differentiation in vitro.

Animals↗
PubMed1985

Induction of spheroplasts in Capnocytophaga ochracea.

A gentle technique for preparing spheroplasts of Capnocytophaga ochracea strain 25 is described. Cells in the exponential phase were washed with 1.0 M-NaCl, agitated in 1.0 M-NaCl for 2 h at 30 degrees C and exposed to lysozyme in a Tris/salts buffer, pH 7.0. This procedure resulted in 98% spheroplast formation with complete removal of the peptidoglycan layer as detected by both phase-contrast and electron microscopy in combination with chemical analysis.

Capnocytophaga↗
PubMed1983

Effects of NaCl on the uptake of alpha-[14C]aminoisobutyric acid by the halotolerant bacterium Halomonas elongata.

The alpha-aminoisobutyric acid (AIB) transport system of the halotolerant bacterium, Halomonas elongata, was examined. Cells were grown in L-alanine defined medium with 0.05, 0.375, 1.37, 2.5, or 3.4 M NaCl. Each group of cells was resuspended in buffered salts with different NaCl concentrations (0.05, 0.375, 1.37, 2.5, and 3.4 M) and the uptake of alpha-[14C]AIB was measured. Optimum AIB uptake occurred in the 0.375 M NaCl solution for the lower salt grown cells and the 1.37 M NaCl solution for the higher salt grown cells. When cells were grown in the higher salt media and suspended in hypoosmotic solutions, appreciable AIB uptake occurred; but for cells grown in lower salt media and suspended in hyperosmotic solutions, the uptake was dramatically reduced. This effect was mainly attributed to cell plasmolysis which in turn resulted in some cell death. The AIB uptake was Na+ specific and this analogue was not metabolized after being transported into the cells. An amino acid competition study gave a pattern similar to that of a marine bacterium.

Amino Acids↗