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Biomedical subjects

D C Alexander

Publications and source records attributed to D C Alexander.

At least 19 recordsLinked to original sources
PubMed1992

U.S. system for organ procurement and transplantation.

The establishment and responsibilities of the organ procurement and transplantation network in the United States are discussed, and the process of receiving an organ transplant through the system is described. The National Organ Transplant Act of 1984 provided for a federally funded network for organ procurement and transplantation, which would function as a private, non-profit organization. This organization is the United Network for Organ Sharing (UNOS). UNOS monitors the activities of and provides service to transplant centers and organ procurement organizations (OPOs). The names of all candidates awaiting cadaveric organ transplants are placed on a central waiting list maintained by UNOS; UNOS also is responsible for maintaining a scientific registry to collect relevant data from transplant centers on the recipients of organ transplants. Although there is a national list of more than 25,000 persons waiting at any given time for a cadaveric organ, there are far fewer actual organ donors (less than 5000 in 1991). The hospital's best resource with respect to the donation process is the local OPO, which provides services related to organ donor referral, evaluation, and surgical recovery. The organ donation process consists of eight components: donor identification, referral, evaluation, consent, management, recovery of organs, allocation, and follow-up. An organ recovery coordinator from the local OPO helps the hospital staff in determining donation potential, seeking consent from the next of kin, and managing the donor after consent has been obtained. The OPO--never the donor's family or their insurer--is billed for charges relating to the donation. The OPO then bills the costs associated with the donation to the transplant centers receiving each organ for implantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1989

Changing trends in dental restorative treatment needs of naval recruits 1987-89--disease or diagnosis?

The restorative treatment needs of 9960 young men and women who entered the Naval Service at HMS Raleigh between January 1987 and April 1989 are summarised. A marked increase in the numbers of fillings required and a decrease in the proportion considered to be dentally fit occurred in May 1988 and has continued as a trend thereafter. Weighted non-orthogonal analysis of variances have been conducted to assess the significance of clinical and period variables upon the changes.

Dental Caries↗
PubMed1987

cDNA cloning and in vitro synthesis of the Dolichos biflorus seed lectin.

The Dolichos biflorus seed lectin contains two structurally related subunits. A cDNA library was constructed using RNA isolated from D. biflorus seeds actively synthesizing the seed lectin. The library was expressed in Escherichia coli using a lambda Charon 16 vector, and lectin-specific antiserum was used to isolate a seed lectin cDNA. Hybridization of the D. biflorus seed lectin cDNA to RNA isolated from seeds actively producing both lectin subunits identifies a single-size RNA of 1100 bases. An oligodeoxyribonucleotide probe, constructed from an amino acid sequence common to both lectin subunits, detects the same size RNA. Translation of seed mRNA in vitro and immunoprecipitation of translation products using a lectin-specific antiserum yields a single polypeptide of slightly higher molecular mass than the largest seed lectin subunit. This seed lectin precursor is indistinguishable from a polypeptide synthesized from mRNA hybrid selected by the seed lectin cDNA. These data support the existence of a single polypeptide precursor for both subunit types of the D. biflorus seed lectin and suggest that differences between the subunit types arise by posttranslational processing.

Amino Acid Sequence↗
PubMed1987

A nutritional analysis of food provided to Royal Naval personnel at sea.

The aim of this study was to determine the nutritional content of the foods provided to, and the confectionary purchased by, personnel serving at sea in British warships. Data were collected from the stores accounts of six ships over a period of 32,354 man-victualling-days. Analysis was carried out at the Nuffield Laboratories of Comparative Medicine. The food from the ships' gallies provided mean daily intakes of 3750 kcal, of which 42 per cent were derived from fats (17 per cent from saturated fats) and 9 per cent from added sugars. In taking account of confectionary purchased from NAAFI sources the total energy intake was raised to 4200 kcal of which 40 per cent were derived from fats (15 per cent saturated fats) and 12 per cent from added sugars. The results do not compare favourably with the recommendations of the reports of expert committees.

Adult↗
PubMed1986

Nucleotide sequence and molecular evolution of two tomato genes encoding the small subunit of ribulose-1,5-bisphosphate carboxylase.

We have isolated and sequenced two cDNA clones (LESS5 and LESS17) encoding the small subunit of ribulose-1,5-bisphosphate carboxylase of tomato (Lycopersicon esculentum). At the nucleotide level, the protein-coding regions of these genes are 85% conserved, while the untranslated 3' regions are only 55% conserved. Comparison with rbcS genes from other species of Solanaceae suggests that the tomato LESS5 gene, the Nicotiana tabacum NTSS23 gene and the Petunia hybrida SSU8 gene are orthologous members of the rbcS gene family. In addition, the tomato gene LESS17, and the Petunia hybrida gene SSU611, may also be orthologous, since their untranslated 3' regions are related. There is a large difference between the two tomato rbcS genes in the frequency of the CG dinucleotide. This difference may reflect different levels of methylation, and therefore expression, of the tomato genes. Many of the differences involving the CG dinucleotide can be represented as transitions between C and T on the noncoding strand. Such changes are consistent with observations that methylated cytosines are hot-spots for transitions.

Base Sequence↗
PubMed1984

A simplified and efficient vector-primer cDNA cloning system.

A simplified, efficient, and versatile vector-primer cDNA cloning system is presented. The dimer-primer system is a modification of the method of Okayama and Berg (1982) with the following features: (i) the vector-primer molecules are more rapidly and reliably prepared by virtue of the elimination of an endonuclease digestion and the agarose gel purification step from the original method, and (ii) the final cDNA products contain polylinkers at both cDNA-vector junctions, simplifying the size analysis, subcloning, and sequencing of inserts. The system is highly efficient, yielding greater than 10(5) transformants using 1 microgram mRNA and 1 pmol of vector-primer ends, with 75% or more of the transformants having inserts. The ability of the system to produce clones of full-length or near full-length is demonstrated by the analysis of 32 ribulose-1,5-bisphosphate carboxylase small subunit cDNA clones from tomato.

Animals↗
PubMed1983

Regulation of beta-chain mRNA of ovine follicle-stimulating hormone by 17 beta-estradiol.

17 beta-Estradiol (E2) rapidly and reversibly decreases the synthesis of follicle-stimulating hormone (FSH) in primary dispersed cell cultures of ovine pituitaries. Similarly, E2 also causes a decrease in the messenger RNA for the beta subunit of ovine FSH (FSH beta-mRNA) as measured in an in vitro translation assay. These results are consistent with the concept that E2 directly regulates either transcription of the FSH beta gene or processing of FSH beta-mRNA in sheep. Of additional interest is the observation that pituitary cultures from various species respond differently to E2 in terms of FSH synthesis. For example, E2 stimulates FSH synthesis in rat pituitary cultures, has no effect in similar rabbit cultures, and inhibits FSH synthesis in ovine cultures. Thus, a set of eukaryotic 'mutants' may exist to aid studies of the effect of E2 on FSH synthesis and secretion.

Animals↗
PubMed1975

Biological characterization of Fusobacterium necrophorum. Cell fractions in preparation for toxin and immunization studies.

Fusobacterium necrophorum isolated from bovine liver abscesses was grown in bulk at 37 C for 24 h under a strict anaerobic atmosphere. Harvested washed cells were disrupted ultrasonically and fractionated by differential centrifugation into the intracellular (cytoplasm) and cell wall fractions. Both intact cells and cell fractions induced generalized cytopathic effect on primary pig kidney cultures and caused a variety of signs of illness and/or death of intraperitoneally injected mice. The intact cells, disrupted cells, and cell walls produced necrotic lesions and erythema on intradermally injected guinea pigs and rabbits, whereas the cytoplasm mainly erythema. By contrast, the used culture medium (culture filtrate) of F. necrophorum did not show any detectable toxicity. The toxic component of the cytoplasm appears to be associated with nondialyzable, hemolytic, high-molecular-weight proteins and its toxicity is reduced by trypsin and pronase. Heating at 60 C for 10 min decreased markedly its erythemal and cytotoxic ability, wheras the toxicity of the cell walls appeared to be only slightly affected even when heated at 100 C for 1 h. These results suggest that at leasttwo distinct cell-bound toxic factors are present in F. necrophorum cells.

Amino Acids↗
PubMed1974

Results of a preliminary trial with Sphaerophorus necrophorus toxoids to control liver abscesses in feedlot cattle.

A preliminary field experiment was undertaken to evaluate the efficacy of alum precipitated toxoids of Sphaerophorus necrophorus prepared from sonicated whole cells and cell fractions to reduce the incidence of bovine abscesses. A total of 108 calves were divided into five groups and treated as follows: I. uninoculated control, II. adjuvant inoculated control, III. 15.5 mg protein of sonicated (fragmented cells) toxoid, IV. 10.5 mg protein of cytoplasmic toxoid. V. 15.5 mg protein of cytoplasmic toxoid. All animals were maintained under similar conditions to those prevailing in feedlots in Alberta. Livers were examined at slaughter. The most promising result was achieved with the injection of 15.5 mg protein of cytoplasmic toxoid. In this treatment group, no scars (healed lesions) were found in the liver and the incidence of liver abscesses was reduced to 10% from the average 35% liver abscesses and scars found in the uninoculated and adjuvant inoculated groups. The toxoid from sonicated whole cells did not reduce liver abscess incidence. These data suggest that the incidence of liver abscesses in cattle fattened in feedlots may be reduced by immunization.

Adjuvants, Immunologic↗
PubMed1971

Bacteriological studies on meat pies and frozen prepared dinners.

A bacteriological survey of meat pies, frozen prepared dinners and entrees indicated that their bacterial populations were related to the components, the environment and handling in manufacture. Results were correlated with microbiological examinations of ingredients, line samples and plant environmental samples. Total bacterial counts, coliform counts and Staphylococcus counts of the finished product were low. Coliform organisms found were primarily Aerobacter spp. originating with the frozen vegetables. Enterococci were also found in the frozen vegetables and finished product. Both enterococci and Aerobacter organisms were recovered from the plant environment where they appeared to multiply. Many of the plant personnel carried coagulase-positive staphylococci in the throat or nasal cavity, and this was indicated as a possible source for these organisms found in low numbers in the finished product. Cooking of the products produced sterility except for the survival of some spore forming Bacillus spp. The presence of a poultry slaughtering operation adjacent to the manufacturing area was considered to contribute to microbial contamination of the air in the plant.

Air Microbiology↗