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Biomedical subjects

R W Jones

Publications and source records attributed to R W Jones.

At least 127 records · Page 7Linked to original sources
PubMed1987

Tryptophan availability of some feedstuffs determined by pig growth assay.

Three experiments were conducted with young pigs to measure the availability of tryptophan in soybean meal, meat and bone meal, cottonseed meal, corn and sorghum. In Exp. 1, a 17.5% crude protein corn and gelatin-based diet, deficient in tryptophan, was supplemented with graded levels of L-tryptophan to establish the growth response of 10- to 20-kg pigs to graded additions of dietary tryptophan. From these data the requirement for maximal growth was calculated to be .16% of the diet using a broken-line model. In Exp. 2, the effects of excess amino acids in a test feedstuff, i.e., soybean meal, on the growth assay method for estimating tryptophan availability was evaluated. The addition of excess crystalline amino acids to the basal diet in proportions equal to the excesses contributed by a test level of soybean meal resulted in a 17.7 percentage unit reduction in the estimate of tryptophan availability (82.3%). When the standard diet was supplemented with amino acids to provide the pattern of excess amino acids found in the corn-gelatin basal diet with added soybean meal, the availability of tryptophan in soybean meal was estimated to be 95.2%. In Exp. 3, the tryptophan availabilities for meat and bone meal, cottonseed meal, corn and sorghum were estimated to be 82.2%, 80.9%, 94.0% and 86.4%, respectively. The diets used in this experiment were supplemented to contain excesses of individual amino acids in the same proportions as found in the basal diet, with the test feed ingredient added as a source of tryptophan. In these experiments the tryptophan content of the various feedstuffs was measured by ion-exchange liquid chromatography following alkaline hydrolysis.

Animal Nutritional Physiological Phenomena↗
PubMed1986

Comparison of epicardial and body surface ECG potentials in man.

Simultaneously measured epicardial electrograms and body surface electrocardiograms in human subjects were compared. Unipolar electrograms were recorded from up to three epicardial sites in each of 21 patients one week after aortocoronary bypass surgery. Simultaneously, electrocardiograms were recorded from 37 body surface electrodes. The epicardial electrograms from ventricular sites correlated well during the QRS complex with body surface electrocardiograms at geometrically similar positions. In particular, most posterior epicardial sites correlated best with posterior body surface regions, contrary to model predictions. P waves recorded from the right atrial surface showed a sharp negative deflection not evident in body surface P waves. A large intersubject variation was evident when the magnitude of epicardial potentials was compared with the body surface potentials. The findings are relevant to the interpretation of surface maps, the estimation of epicardial potentials from surface maps, and the positioning of body surface electrodes.

Electrocardiography↗
PubMed1986

Carcinoma in situ of the vulva: a review of 31 treated and five untreated cases.

Thirty six patients with carcinoma in situ of the vulva have been followed from two to 23 years. Among 31 patients managed by surgical excision, there were four recurrences of vulvar carcinoma in situ and one patient developed a vulvar carcinoma 17 years later. Four middle-aged and elderly women managed only by biopsy all progressed to invasive vulvar carcinoma in two to eight years; one additional patient progressed to invasion after inadequate primary treatment. These last five cases all represented multifocal lower genital tract neoplasia. Untreated vulvar carcinoma in situ, when seen as part of a multifocal lower genital tract neoplastic process, in middle and later life is likely to progress to invasion.

Adult↗
PubMed1985

Analysis of an inversion within the human beta globin gene cluster.

We have cloned and sequenced the DNA from two regions of the defective beta-globin gene cluster from a patient with Indian A gamma delta beta thalassaemia, and confirmed the complex and unusual pattern of rearrangement involving two separate deletions (0.8 kb and 7.5 kb) the inversion of the 15.5 kb segment separating them, as previously proposed from gene mapping studies [1]. All four breakpoints occur within the transcribed region of the globin genes and at one junction are found six nucleotides of unknown origin. This unique rearrangement results in enhanced expression of the upstream fetal gene, and is therefore is pertinent to the localisation of any putative control region involved in the coordinate expression of fetal and adult genes.

Base Sequence↗
PubMed1985

Two cases of X/autosome translocation in females with incontinentia pigmenti.

We report two unrelated girls who present some clinical features of severe incontinentia pigmenti (IP), with characteristic skin pigmentation. Both have balanced de novo X/autosome translocations involving band Xp11. The coincidence of the probable de novo expression of an X-linked disorder in these two girls with translocations involving similar breakpoints on the X chromosome suggests that this band may be the site of the IP gene locus.

Child, Preschool↗
PubMed1985

Penbutolol and propranolol: a comparison of their effects on antipyrine clearance in man.

The effects of two beta-adrenoceptor antagonists, penbutolol (administered on separate occasions as (+/-)- and (-)-forms) and propranolol, on the kinetics of antipyrine were studied in eight normal subjects. At the same degree of beta-adrenoceptor blockade, as assessed by the lowering of exercise tachycardia, propranolol decreased antipyrine clearance by 31 +/- 11 s.d.% (P less than 0.001) whereas neither of the two penbutolol formulations had a significant effect. The volume of distribution of antipyrine was unchanged following any of the beta-adrenoceptor antagonist treatments. The lack of effect of penbutolol on oxidative drug metabolism is not consistent with in vitro data suggesting a relationship between the lipid solubility of beta-adrenoceptor antagonists and inhibition of metabolism.

Adult↗
PubMed1985

The sequence of the A gamma globin gene in a G gamma beta+ type of hereditary persistence of fetal haemoglobin.

The sequence of the A gamma globin gene from the affected chromosome of an individual heterozygous for the G gamma beta+ type of hereditary persistence of fetal haemoglobin (G gamma beta+ HPFH) is reported. With two exceptions, it is identical to one of the two allelic A gamma globin genes already sequenced and there is therefore no change which could explain the absence of its expression in the face of the persistent G gamma globin expression which is a feature of this condition.

Alleles↗
PubMed1985

Effect of the beta-adrenergic agonist cimaterol (CL 263,780) on the growth and carcass characteristics of finishing swine.

A randomized complete-block design was used to evaluate the effects of the beta-adrenergic agonist, cimaterol (CL 263,780), on growth rate, feed efficiency and carcass composition of finishing swine. The drug was fed at four levels (0, .25, .5 and 1.0 ppm) to a total of 240 pigs from 64.5 to 103.7 kg live weight. Growth rate and feed efficiency were measured during the 7-wk feeding trial. Feeding cimaterol depressed feed intake, improved feed efficiency and did not alter rate of gain. Carcass evaluation showed that pigs continuously fed cimaterol had 13.2, 9.3 and 9.2% less fat measured at the 10th rib, P2 and average backfat (BF) locations, respectively, compared with controls. Cimaterol-fed pigs had increased loin eye areas (10.9%), and increased semitendinosus (11.8%) and biceps femoris (8.9%) weights compared with controls. The semitendinosus muscles of the cimaterol-fed pigs had less fat and the femur bones were shorter and lighter weight than controls. There were no detected differences in structural soundness of the live pigs, but postmortem evaluation of the hooves indicated that pigs fed 1.0 ppm cimaterol had a higher incidence of hoof lesions. Pigs withdrawn from cimaterol for 7 d were comparable in performance and carcass characteristics with those continuously fed the drug except that carcass fat measurements had generally returned to control values. The data indicate that cimaterol improved the feed efficiency of finishing pigs and increased the lean:fat ratio of their carcasses. Withdrawal of cimaterol caused compensatory fat deposition.

Adipose Tissue↗
PubMed1985

The developmental genetics of human hemoglobin.

Clearly, it is impossible to combine the diverse information briefly outlined in this review to provide a coherent model of the regulation of globin gene expression during development. One of the great difficulties in this field is uncertainty as to whether the mutations which are associated with persistent gamma chain production or, for the matter, the experimental models which have been used to study the differential expression of the fetal and adult globin genes, have any real relevance to an understanding of the normal switching process. Probably they do, but only with respect to one aspect of what must be an extremely complex multi-step regulatory system. The consistent changes in chromatin and methylation state of the beta globin gene cluster which are associated with activation of the different gene loci at different stages of development provide an anatomical explanation for the activity of these loci but tell us nothing about their mode of regulation. However, the gene or chromosome transfer experiments suggest that there may be developmental-stage specific trans regulatory factors which may be involved in the regulation of these genes, presumably by interacting in some way with chromatin. This is a very promising lead. Equally interesting is the possibility that the upstream mutations which are being found in some of the forms of non-deletion HPFH could provide a clue as to the site of these interactions. Thus at least we have an indication of what might be the most productive area of investigation for trying to characterize the mechanisms of regulation at the chromosomal level. This may be as far as we can go in the immediate future. The central question remains, however. How is the differential expression of the globin genes during development actually timed? All we know at the moment is that it is related fairly closely to gestational age. The only experimental data relating to this question is derived from the sheep transplant model, and suggests that there might be some form of "developmental clock' built into the hemopoietic stem cell. Here we are in considerable difficulties because we don't have an obvious experimental model with which to analyze time-related events. None of the forms of HPFH is, strictly speaking, a heterochronic mutation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1984

A model for the structure of fumarate reductase in the cytoplasmic membrane of Escherichia coli.

By a recombinant DNA approach we have prepared Escherichia coli cytoplasmic membranes that are highly enriched in the terminal electron transfer enzyme fumarate reductase. This enzyme is composed of four nonidentical subunits in equal molar ratio. A 69,000-dalton covalent flavin-containing subunit and a 27,000-dalton nonheme iron-containing subunit make up a membrane extrinsic catalytic domain. Two very hydrophobic subunits of 15,000 and 13,000 daltons make up the hydrophobic membrane anchor domain. Electron microscopy of negatively stained membranes shows a characteristic knob-and-stalk-type structure composed of the catalytic domain. The anchor polypeptides have been analyzed for hydrophobic segments and alpha-helical content and a model for their organization within the lipid bilayer is presented. The results reviewed in this paper suggest a model for the fumarate reductase complex in the cytoplasmic membrane.

Bacterial Proteins↗
PubMed1984

(A gamma delta beta) thalassaemia: similarity of phenotype in four different molecular defects, including one newly described.

Globin gene mapping of DNA from families with (A gamma delta beta) thalassaemia has revealed a previously unreported gene deletion responsible for this condition. The deletion removes the A gamma, delta and beta genes and while its 5' end is in a similar position to that described in a previous deletion of this type, the 3' ends of the two deletions are quite different. In addition we have observed further examples of two other previously described deletions which result in this disorder. Phenotypic comparisons of families with (A gamma delta beta) thalassaemia, in which the molecular basis has been defined, show a remarkable similarity among the four different deletion defects, with important implications with regard to the mechanism by which deletions allow the continued expression of gamma genes.

Adolescent↗
PubMed1984

Hydrocephalus and primary ciliary dyskinesia.

Primary ciliary dyskinesia was shown in a 12 year old boy with bronchiectasis who had developed hydrocephalus in the neonatal period. The possible relevance of his ciliary abnormality is discussed.

Child↗
PubMed1984

The invasive potential of carcinoma in situ of the cervix.

Nine hundred and forty-eight patients with carcinoma in situ (CIS) of the cervix diagnosed histologically have been followed from five to 28 years. Among the 817 patients who had normal cytology follow-up, 12 (1.5%) developed invasive carcinoma. A second group of 131 patients continued to produce abnormal cytology consistent with cervical neoplasia, and 29 (22%) of them developed invasive carcinoma of the cervix or vaginal vault. Patients with continuing abnormal cytology after initial management of CIS of the cervix are 24.8 times more likely to develop invasive carcinoma than women who have normal follow-up cytology. Further, when compared with the population at large, the chances of patients with normal follow-up cytology developing invasive cervical or vaginal vault carcinoma increase 3.2-fold over women who have never had CIS of the cervix.

Adolescent↗