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Biomedical subjects

R M Davis

Publications and source records attributed to R M Davis.

At least 37 records · Page 2Linked to original sources
PubMed2000

Phylogenetic relationships of necrogenic Erwinia and Brenneria species as revealed by glyceraldehyde-3-phosphate dehydrogenase gene sequences.

Recent examination of the relationships of the dry necrosis-inducing (necrogenic) erwinias using 16S rDNA sequences demonstrated that these bacteria comprise a polyphyletic group and, therefore, have been subdivided into three distinct genera, Erwinia, Brenneria and Pectobacterium, with the classical 'amylovora' group species now being distributed nearly evenly among the first two. To further assess the molecular evolutionary relationships between current necrogenic Erwinia and Brenneria species, as well as between these genera and the exclusively soft-rotting genus Pectobacterium, the glyceraldehyde-3-phosphate dehydrogenase (gapDH) genes from 57 Erwinia and Brenneria isolates along with Pectobacterium type strains were PCR-amplified, sequenced and subjected to phylogenetic analysis. Pairwise alignments of cloned gapDH genes revealed remarkably high interspecies genetic diversity among necrogenic isolates. Four evolutionary clades of necrogenic species were described that assorted more closely to known soft-rotting species than to each other. Interclade comparisons of gapDH nucleotide sequences revealed as much genetic divergence between these four necrogenic clades as existed between necrogenic and soft-rotting clades. An examination of the phylogenetic utility of the gapDH gene in light of current 16S rDNA clustering of these species revealed varying levels of taxonomic congruence between these genes for the structure of Erwinia, Brenneria and Pectobacterium. These analyses suggest that, while gapDH possesses sufficient genetic variation to fully differentiate Erwinia and Brenneria species, the gene may not accurately reflect interspecies taxonomic relatedness among all three phytopathogenic genera.

DNA, Ribosomal↗
PubMed1999

Corneal wound-associated glycoconjugates analyzed by lectin histochemistry.

PURPOSE: To examine changes in corneal glycoconjugates during wound healing in a pig model of refractive surgery. METHODS: Pig corneas were wounded using a mechanized microkeratome. Lamellar keratectomy, without replacement of a corneal cap, or automated lamellar keratoplasty, with replacement of a corneal cap, was performed. Corneas were prepared for microscopy 1, 7, or 28 days after surgery. Cryosections of corneas were probed with lectins recognizing a variety of carbohydrate moieties. Glycoconjugates were characterized by glycosidase digestion and chemical extraction. RESULTS: Of the lectins used, only that from Dolichus biflorus (DBA), specific for terminal N-acetylgalactosamine, exhibited a dramatic change in staining pattern after wounding. In unwounded corneas, DBA labeled the superficial epithelium, Bowman's layer, and occasional keratocytes. After wounding, DBA intensely labeled exposed stromal surfaces and keratocytes near wound sites. RESULTS of glycosidase treatments indicated that the DBA-binding material contains alpha-linked N-acetylgalactosamine. After extraction with lipid solvents, stromal DBA labeling was unchanged, while that of keratocytes was greatly diminished. CONCLUSIONS: Corneal wounding results in the accumulation of specific glycoconjugates at surfaces and in keratocytes. After keratectomy, the exposed stromal surface is infiltrated with ocular surface components, including DBA-binding glycoproteins. The presence of these components may influence the course of wound healing. In addition, changes in keratocyte glycoconjugates may accompany their mobilization to the wound-repair phenotype.

Acetylgalactosamine↗
PubMed1999

Use of orally administered chitin inhibitor (lufenuron) to control flea vectors of plague on ground squirrels in California.

The efficacy of orally administered lufenuron, a chitin inhibitor, to control fleas on California ground squirrels, Spermophilus beecheyi (Richardson), was evaluated during a 2-yr study in Santa Barbara County, CA. Results demonstrated that use of a host-targeted feed cube containing lufenuron was effective in significantly reducing the burden of Oropsylla montana (Baker) and Hoplopsyllus anomalus (Baker) fleas on ground squirrels. A flea index that indicated a mean number of fleas per squirrel of 10.0 decreased to 1.3 after 2 treatments in season 1, and to 0.7 and 0.2 after the 3rd and 4th treatments, respectively, in season 2. A cost comparison of this new method compared with a traditional reactive, emergency, insecticide-based plague control program demonstrated a cost reduction of approximately 90%. The results of this study indicated that a lufenuron feed cube was an effective, cost-saving, and proactive technique for controlling fleas on California ground squirrels, and thus reducing the risk of disease transmission in plague endemic regions.

Administration, Oral↗
PubMed1998

Sleepiness, driving, and motor vehicle crashes. Council on Scientific Affairs, American Medical Association.

OBJECTIVE: To assess the contribution of driver sleepiness to highway crashes and review recent recommendations to change federal hours-of-service regulations for commercial motor vehicle drivers. DATA SOURCES: Information was derived from a search of the MEDLINE, Transportation Research Information Service (TRIS), and Bibliographic Electronic Databases of Sleep (BEDS) databases from 1975 through 1997 and from manual review of the reference lists in relevant journal articles, government publications, conference proceedings, and textbooks. DATA SYNTHESIS: Driver sleepiness is a causative factor in 1% to 3% of all US motor vehicle crashes. Surveys of the prevalence of sleepy behavior in drivers suggest that sleepiness may be a more common cause of highway crashes than is reflected in these estimates. About 96% of sleep-related crashes involve passenger vehicle drivers and 3% involve drivers of large trucks. Risk factors include youth, shift work, alcohol and other drug use, over-the-counter and prescription medications, and sleep disorders. CONCLUSIONS: Increased awareness of the relationship between sleepiness and motor vehicle crashes will promote the health and safety of drivers and highway users. Physicians can contribute by encouraging good sleep habits, recognizing and treating sleep-related problems, and counseling patients about the risks of driving while sleepy. To protect public health and safety, the American Medical Association recommends continued research on devices and technologies to detect the signs of sleepiness and prevent the deterioration of driver alertness and performance. Educational programs about the risks of falling asleep while driving are needed for physicians, the public, and commercial truck drivers.

Accidents, Traffic↗
PubMed1998

The U.S. Preventive Services Task Force Guide to Clinical Preventive Services, Second Edition. AMA Council on Scientific Affairs.

A resolution, introduced by the American College of Preventive Medicine at the 1996 American Medical Association (AMA) Annual Meeting, asked the AMA to recommend to physicians the use of the United States Preventive Services Task Force's Guide to Clinical Preventive Services, Second Edition. In response to that resolution, the AMA's Council on Scientific Affairs has reviewed and evaluated this publication. The recommendations of the Council on Scientific Affairs on the use of the Guide to Clinical Preventive Services, Second Edition, by clinicians and medical educators are included in this report. These recommendations were adopted as AMA Policy at the AMA Annual Meeting in June 1997.

Government Publications as Topic↗