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Biomedical subjects

C Hunt

Publications and source records attributed to C Hunt.

At least 91 records · Page 5Linked to original sources
PubMed1984

The clinical and biochemical effects of vitamin C supplementation in short-stay hospitalized geriatric patients.

A double-blind placebo trial has been undertaken on 199 elderly patients admitted to an "acute" geriatric assessment ward. Clinical and biochemical assessment was made on admission (0) and at 2, 4, 8, 16 and 24 weeks (after admission). Ninety-four patients were supplemented with vitamin C (200 mg per day) and 105 had placebo tablets. Biochemical assessment included estimations of plasma and leucocyte (buffy layer) vitamin C, plasma folate, vitamin B12, cortisol and total white cell count. Plasma and leucocyte vitamin C levels remained low for several weeks in a substantial proportion of the non-supplemented patients, whereas low levels were virtually eliminated in the supplemented group. The results from this study suggest that the leucocyte vitamin C levels may give some indication of prognosis in this category of patients (ie. "acute" geriatric admissions) as evidenced by: i) the significantly higher mortality rate during the trial period of patients who started with low initial leucocyte vitamin C levels compared with those starting with higher levels, despite similar mean initial "severity of illness scores" between the two groups. ii) the marked trend, amongst placebo subjects, for those commencing the study with higher leucocyte vitamin C levels to fare better, in terms of progression to "well", than those starting with low levels. Amongst subjects starting with low leucocyte vitamin C levels, there was a trend for "vitamin C" subjects to have fared better by 8 weeks than "placebo" subjects. This again occurred despite similar mean initial "severity scores" between the two groups. Amongst subjects diagnosed with respiratory infections there was some tendency for supplemented patients to fare better than unsupplemented patients. Low leucocyte vitamin C levels, on admission, appear to be predictive of poor subsequent prognosis in elderly hospitalised patients. Results from this trial suggest that supplementation with a moderate dose of vitamin C may improve this prognosis and larger trials with greater numbers appear to be merited to confirm or deny this hypothesis.

Aged↗
PubMed1984

Nutrition and catering: 3. Nutrient losses in cook-freeze and cook-chill catering.

Information on nutrient losses in cook-chill and cook-freeze catering systems is reviewed, which is limited and conflicting. In general it suggests that cook-freeze systems result in better vitamin C retention than conventional systems with significant warmholding periods. Losses of vitamin C, and possibly other labile nutrients appear to be significant in cook-chill systems.

Ascorbic Acid↗
PubMed1983

Microtubule polarity in the nutritive tubes of insect ovarioles.

The enormous numbers of microtubules within the nutritive tubes of hemipteran ovarioles are amenable to the hook-decoration technique for determining microtubule structural polarity, as they can be microdissected from ovarioles intact. This has allowed the correlation between the polarity of this continuously elongating complex of microtubules within a nutritive tube and the direction of transport along its length; and has shown that the plus or fast growing ends of the microtubules are all situated at the anterior end of a nutritive tube proximal to the trophic region from which synthesised materials are passed back towards the developing oocytes.

Animals↗
PubMed1983

Perinatal stress: a study of factors linked to the risk of parenting problems.

Infants who are born preterm are at high risk for subsequent maltreatment. This study examines the relationship between family functioning, infant morbidity, parents' experience following their infant's admission to a neonatal intensive care unit, and postdischarge risk of parenting problems. For the sample as a whole, family factors emerged as the best predictors of outcome.

Anxiety↗
PubMed1982

The nature of the clear zone around microtubules.

The clear zones seen around microtubules in transverse sections of nutritive tubes vary in size depending on whether a microtubule is bordered by ribosomes or by another microtubule. We consider that such a finding is not consistent with the current view, that the clear zone is maintained by microtubule-associated material. It can, however, be accounted for by an electrostatic repulsion between the surfaces of negatively charged microtubules and between microtubules and ribosomes which are also negatively charged. The experiments presented here, involving on the one hand the addition of cationic substances to microtubules and on the other the alteration in charge of the microtubules, support this hypothesis.

Animals↗
PubMed1980

Bacteriophage T5 transfer RNA. Isolation and characterization of tRNA species and refinement of the tRNA gene map.

Previous studies from this laboratory have provided a high resolution map for 16 tRNA genes located on the continuous heavy DNA strand of bacteriophage T5 DNA (Chen, M.-J., Locker, J., and Weiss, S.B. (1976) J. Biol. Chem. 251, 536-547). All of the T5 tRNA genes were located in three clusters within the DNA C segment, except for tRNAArg, which mapped on the left end of the DNA D segment (Desai, S.M., Hunt, C., Locker, J., and Weiss, S.B. (1978) J. Biol. Chem. 253, 6544-6550). In this report, we present evidence for the presence of eight additional T5 tRNA species, five of which are located in two new loci within the DNA C segment. We also describe a two-dimensional gel electrophoresis system for the separation and isolation of T5 tRNA species from crude infected RNA preparations. The gel electrophoresis system separates tRNA isoacceptors specific for different amino acids; evidence is presented that the isoacceptors for isoleucine, histidine, and serine are coded by different T5 genes.

Base Sequence↗
PubMed1980

Acute systemic toxicological tests of soft contact lens extractives.

The toxic potential of three major components of soft contact lenses was assessed in white mice. Accepted procedures for toxicological studies were used to evaluate the effects of 2-hydroxyethyl methacrylate, ethylene glycol, and methacrylic acid. No observable signs of gross toxicity were detected in any of the mice injected with the original doses. Larger doses of methacrylic acid produced ataxia, irregular breathing, convulsions, and death. From the concentrations of these chemicals normally occurring in contact lenses, no systemic toxic effects would be expected.

Animals↗
PubMed1978

Localization of the arginine tRNA gene to the D segment of T5 bacteriophage DNA. A new procedure for producing duplex DNA fragments.

The tRNA genes of bacteriophage T5 are located in four clusters on the continuous heavy DNA strand (Chen, M.-J., Locker, J., and Weiss, S.B. (1976) J. Biol. Chem. 251, 536--547). Three of the four clusters are within the DNA C segment; the fourth cluster, to which only tRNAArg has been localized, maps in a 3.02 kilobase (kb) region of which 1.99 kb are at the right end of the C segment and 1.03 kb at the left end of the D segment. In order to localize the tRNAArg gene further and to define its relationship to the C-D nick, we devised a suitable method for preparing T5 DNA fragments whose ends correspond to the position of the T5 DNA nicks contained in the light DNA strand. In this method, DNA is denatured, partially renatured, and digested with low concentrations of S1 nuclease. Agarose-gel electrophoresis of these digests gives a pattern of bands which correlate in size with the pattern expected from the nicked structure of T5 DNA. Annealing of individual purified T5 [35P]tRNA species to the T5 DNA fragments transferred to nitrocellulose filters shows that tRNAArg hybridizes exclusively to the D fragment and is therefore localized to 1.03 kb at the 5' (left) end of the heavy strand of the D segment. This finding suggests that the promotor for this early gene is to the right of the C-D nick in T5 DNA; hence, the C-D nick does not coincide with this early promotor.

Arginine↗
PubMed1977

Lymphocyte and fibroblast chalones: some chemical properties.

Experiments with lymphocyte and fibroblast chalones indicate that they are complexed strongly with RNA in tissue extracts; have a molecular weight of less than 10,000 and more than 1,000 daltons, and probably about 5,000 daltons; are strongly cationically charged; and contain mannose and perhaps other carbohydrates.

Cell Division↗
PubMed1976

Mapping of two isoleucine tRNA isoacceptor genes in bacteriophage T5 DNA.

T5 bacteriophage codes for the synthesis of more than 14 different tRNA species, which map in four separate clusters in the C segment of the T5 chromosome. In this study, two tRNAile isoacceptor species have been identified by reverse-phase chromatography and shown to be transcribed from two different tRNA loci along the T5 chromosome. The map positions of the tRNA isoacceptors were aided by the use of several T5 deletion mutants in which the position and size of the deleted DNA segments had been previously determined by heteroduplex mapping. Hybridization analysis suggests the presence of some sequence homology between the two tRNAile species.

Chromosome Mapping↗