Search PubMed⌕ Search

Biomedical subjects

R Jones

Publications and source records attributed to R Jones.

At least 757 records · Page 42Linked to original sources
PubMed1988

Effect of ischemia and reperfusion of the myocardium on in vitro beta-oxidation of fatty acids.

The in vivo oxidation of perfused [14C]-labeled fatty acids has been shown to decrease dramatically in hypoxic hearts. This study addresses the influence of ischemia and reperfusion on the enzymic activities of beta-oxidation of fatty acids in mitochondria and of peroxisomal origin. The rate of beta-oxidation of fatty acids in the isolated mitochondria from myocardium of swine fed control diet declined about 20% by the ischemic insult induced by hypothermic cardioplegic arrest. Upon reperfusion, the rate of mitochondrial beta-oxidation returned to a normal level. In clofibrate-fed animals, the rate of mitochondrial beta-oxidation did not vary significantly between control, ischemic, and perfused tissues. Furthermore, neither in control nor in clofibrate-fed animals did the rates of peroxisomal beta-oxidation of fatty acids vary significantly in the ischemic or reperfused tissues as compared to that of preischemic controls. These results suggest that ischemia does not contribute to any loss of enzymic activity in beta-oxidation of fatty acid cycles either in mitochondria or peroxisomes. Furthermore, the feeding of 0.5% (w/w) clofibrate to pigs increased the rate of mitochondrial beta-oxidation of fatty acids only by 50% while that of peroxisomes increased threefold. A similar threefold increase in catalase activity was also produced by clofibrate feeding. These results suggest that the heart plays a role in the hypolipidemic action of clofibrate.

Animals↗
PubMed1988

Variability in 28-day outcomes for very low birth weight infants: an analysis of 11 neonatal intensive care units.

A retrospective study of all infants weighing 701 to 1,500 g born at 11 neonatal intensive care centers during 1983 and 1984 was performed to determine whether two specific 28-day outcomes, survival and survival without the need for supplemental oxygen, varied among the centers. Survival without the need for supplemental oxygen was chosen as a reflection of infants surviving without chronic lung disease. There were 1,776 live-born infants delivered during the 2-year study period. Of these infants, 85% (1,512) survived 28 days, a range of 80% to 92% at the individual centers. A total of 60% (1,056) of the infants were alive without supplemental oxygen on day 28, a range of 51% to 70% at the individual centers. Multivariate analysis demonstrated that both survival on day 28 (chi 2 = 23.9, P less than .01) and survival without supplemental oxygen on day 28 (chi 2 = 44.2, P less than .0001) varied significantly among centers after the effects of birth weight, gender, and race were taken into account. Female gender, nonwhite race, and increased birth weight were factors associated with improved rates of survival and survival without supplemental oxygen. The magnitude of outcome variation among centers was estimated by using the logistic regression models to predict what the outcomes would be if each center were to treat a standardized population consisting of all 1,776 study infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Weight↗
PubMed1988

Hemodynamic and pathologic effects of prostacyclin on oleic acid-induced pulmonary injury.

Oleic acid (OA) injection into the lungs of dogs produces pulmonary edema and decreased cardiac output, and the result is combined hypoxic and stagnant hypoxia. Prostacyclin (PGI2) has some effects that may be beneficial in the alleviation of hypoxia. We studied 18 anesthetized dogs that were divided into three groups: (1) Six dogs acted as controls and did not receive OA or PGI2, (2) six dogs received OA but no PGI2, and (3) six dogs were first given OA and 1 hour later an infusion of PGI2 (100 ng/kg/min) was started and continued for 4 hours. All dogs were killed at the end of the study and their lungs were removed for weighing and preparation for microscopic examination. Compared with controls, OA caused a low cardiac output, high systemic and pulmonary vascular resistance, and increased right-to-left intrapulmonary shunt. The group that received OA and PGI2 demonstrated a well-maintained cardiac output and a low systemic vascular resistance. Right-to-left intrapulmonary shunt, however, increased in these dogs compared with the dogs not given PGI2. All animals given OA had similar wet/dry lung weights and histologic appearances. Our results suggest that the only beneficial effect of PGI2 in OA-induced lung injury is to improve the stagnant hypoxia, but this is associated with an aggravation of the hypoxic hypoxia. The result of these competing effects appears to be a mild overall improvement in oxygen delivery as suggested by the slightly higher mixed venous PO2 in the group that received PGI2.

Animals↗
PubMed1988

Effects of chronic endotoxaemia on oxygen consumption at different ambient temperatures in the unanaesthetised rat.

Oxygen consumption has been measured at different ambient temperatures at intervals during the intravenous infusion of endotoxin (1 mg/kg.day-1) from a subcutaneously implanted osmotic minipump in unanaesthetised rats. On day 1 of the infusion oxygen consumption was elevated at ambient temperatures of 10, 28, and 31 degrees C but not at 20 degrees C, compared with pair-fed saline-infused controls. There was a significant negative correlation between oxygen consumption on days 1 and 3 and environmental temperature (10, 20, and 28 degrees C) in both groups, but the regression line describing the relation in endotoxin-infused rats was displaced above that for the saline-infused control without a change in slope. The "minimal observed" oxygen consumption, which is taken as an estimate of basal metabolic rate, was elevated by the infusion of endotoxin. The endotoxin-induced increase in "minimal observed" oxygen consumption was removed by indomethacin (5 mg/kg.sc) on day 1 of the infusion but was ineffective on days 3 and 7.

Animals↗
PubMed1987

A dumbbell-shaped, double-hairpin structure of DNA: a thermodynamic investigation.

We report the first calorimetric and spectroscopic investigation on a member of a new class of nucleic acid secondary structures in which both ends of a duplex core are closed by single-stranded loops. Such structures can be formed intramolecularly from appropriately designed base sequences. We have synthesized the 24-mer sequence shown, and we present calorimetric, spectroscopic, and electrophoretic (formula; see text) evidence that it adopts a dumbbell-shaped, double-hairpin structure. Our data allow us to reach the following conclusions: (1) The phosphodiester gap in the center of the core duplex of the dumbbell does not reduce the transition enthalpy relative to that measured for the corresponding octameric duplex d(GGAATTCC)2. (2) Incorporation of a 5'-phosphate group into the gap decreases the thermal stability of the dumbbell relative to its unphosphorylated sequence. On the basis of the salt dependence of this effect, we propose that the phosphorylation--induced decrease in thermal stability is electrostatic in origin. From the changes in the transition enthalpy and entropy, we suggest that the phosphorylation-induced decrease in thermal stability of the double hairpin arises from electrostatically induced based unstacking at the nick. (3) The thymine residues in the loop behave both electrostatically and enthalpically like denatured single strands. Published nuclear magnetic resonance studies reveal partial stacking of thymine residues in the loops of linear hairpin structures. If this feature persists in the double-hairpin structure, then the spatial overlap of thymine residues in the loops does not necessarily produce a favorable enthalpic contribution. (4) When both ends of the nicked octameric core duplex are constrained by loops of only four thymine residues, the dumbbell structure may adopt conformations in which the 5' and 3' ends at the nick are twisted relative to the helical axis and therefore are not in phase. Such conformations would account for the observed resistance of the double-hairpin structure to ligation, since the 3'OH and 5'P would no longer be collinear.

Base Sequence↗
PubMed1987

The primary structure of rat ribosomal protein S12. The relationship of rat S12 to other ribosomal proteins and a correlation of the amino acid sequences of rat and yeast ribosomal proteins.

The covalent structure of the rat 40 S ribosomal subunit protein S12 was determined from the sequence of amino acids in tryptic, chymotryptic, thermolytic, and cyanogen bromide peptides and inferred from the sequence of nucleotides in a recombinant cDNA. Rat ribosomal protein S12 contains 129 amino acids and has a molecular weight of 14,120. The amino acid sequences of a number of ribosomal proteins appear to be related to rat S12. These include spinach chloroplast L7, Escherichia coli S5, Nicotiana tabacum chloroplast S18, and Bacillus stearothermophilus S12, and perhaps others. In addition, there are two sequences, 26 and 18 amino acids in length, in rat S12 that may be related to segments of the same number of residues in ribosomal proteins from a number of species. These, and other results, reinforce the suggestion that ribosomal proteins form an extended family.

Amino Acid Sequence↗
PubMed1987

Restriction endonucleases for pulsed field mapping of bacterial genomes.

Fundamental to many bacterial genome mapping strategies currently under development is the need to cleave the genome into a few large DNA fragments that can be resolved by pulsed field gel electrophoresis. Identification of endonucleases that infrequently cut a genome is of key importance in this process. We show that the tetranucleotide CTAG is extremely rare in most bacterial genomes with G+C contents above 45%. As a consequence, most of the sixteen bacterial genomes we have tested are cleaved less than once every 100,000 base pairs by one or more endonucleases that have CTAG in their recognition sequences: Xba I (TCTAGA), Spe I (ACTAGT), Avr II (CCTAGG) and Nhe I (GCTAGC). Similarly, CCG and CGG are the rarest trinucleotides in many genomes with G+C content of less than 45%. Thus, Sma I (CCCGGG), Rsr II (CGGWCCG), Nae I (GCCGGC) and Sac II (CCGCGG) are often suitable endonucleases for producing fragments that average over 100,000 base pairs from such genomes. Pulsed field gel electrophoresis of the fragments that result from cleavage with endonucleases that cleave only a few times per genome should assist in the physical mapping of many prokaryotic genomes.

Base Composition↗
PubMed1987

Severe hypophosphatemia associated with diabetes mellitus in six dogs and one cat.

Severe hypophosphatemia was found in 6 diabetic dogs and in one diabetic cat. The cat suffered from hemolysis, and one dog had seizures, both apparently as a result of the severe hypophosphatemia. Clinical signs were not determined solely by the serum concentration of phosphorus, as seen in 5 other patients that did not have signs of disease despite similar serum phosphorus concentrations.

Animals↗
PubMed1987

Identification and characterization of the 2D6 and Mr 23,000 antigens on the plasma membrane of rat spermatozoa.

Previous investigations [Jones, Brown, von Glos & Gaunt (1985) Exp. Cell Res. 156, 31-44] have demonstrated the appearance of a new antigenic determinant (recognized by monoclonal antibody 2D6) on the plasma membrane of rat spermatozoa during post-testicular maturation in the epididymis. Identification of the 2D6 antigen on Western blots from one-dimensional SDS/polyacrylamide gels revealed that it co-migrated with a membrane protein (designated Mr 23,000 antigen) present on testicular and immature germ cells, suggesting that one antigen might be a modified version of the other. In the present work, however, we demonstrate that, although they have similar Mr and are present in soluble and membrane-bound forms, the 2D6 and Mr 23,000 antigens are biochemically and immunologically distinct molecules. The properties of the antigens are described and compared. The Mr 23,000 antigen is present on both testicular and cauda epididymidal spermatozoa, has a pI of 6.1, contains no detectable carbohydrate, is not tissue-specific and is degraded by V8 protease. By contrast, the 2D6 antigen is glycosylated, has a broad pI from 4.5 to 6.1, is tissue- and species-specific and is resistant to digestion with V8 protease. Its role in sperm-egg recognition is discussed.

Animals↗
PubMed1987

The morbidity and mortality of vermiculite miners and millers exposed to tremolite-actinolite: Part III. Radiographic findings.

A study was conducted to estimate the exposure-response relationship for tremolite-actinolite fiber exposure and radiographic findings among 184 men employed at a Montana vermiculite mine and mill. Workers were included if they had been employed during 1975-1982 and had achieved at least 5 years tenure at the Montana site. Past fiber exposure was associated with an increased prevalence of parenchymal and pleural radiographic abnormalities. Smoking was not significantly related to the prevalence of small opacities. However, the number of workers who had never smoked was small, and this prevented measurement of the smoking effect. Under control for smoking and age, the prevalence of small opacities was significantly greater for vermiculite workers with greater than 100 fiber/cc-years exposure than for comparison groups (cement workers, blue collar workers, and coal miners) who had no known occupational fiber exposure. A logistic model predicted an increase of 1.3% in the odds ratio for small opacities at an additional exposure of 5 fiber-years.

Adult↗
PubMed1987

Identification of a zona-binding protein from boar spermatozoa as proacrosin.

The initial stages of fertilization in vertebrates and invertebrates are thought to involve complementary recognition molecules on spermatozoa and eggs. In a previous work (C. R. Brown and R. Jones, 1987, Development) we described one such putative molecule (a protein of approximate molecular weight 53 kDa) in detergent extracts of boar spermatozoa that has affinity for glycoproteins from the zona pellucida of pig eggs. This molecule has now been identified as proacrosin, the zymogen form of the acrosomal protease acrosin, on the basis of its electrophoretic behavior, the ability of zona glycoproteins to recognize and bind to proacrosin on Western blots, and the cross-reactivity of specific antisera to the 53-kDa molecule and proacrosin. A role is proposed for this enzyme in binding the sperm head to the zona pellucida during the initial stages of sperm-egg interaction.

Acrosin↗
PubMed1987

In vitro ADP-ribosylation of nuclear proteins in mouse tissues. Identification of an unusual group of acceptors in testis nuclei.

1. Acceptor proteins for poly(ADP-ribose) have been identified in nuclei from mouse testis, liver, kidney and spleen. Purified nuclei were incubated in vitro with [14C]NAD, extracted sequentially with 5% HClO4 and 0.25 N-HCl and labelled proteins analysed on acetic acid/urea polyacrylamide gels pH 2.9. 2. Results show that: (a) in vitro there are significant differences between tissues in the extent of poly(ADP-ribosylation) of nuclear proteins; (b) in testis nuclei two tissue specific proteins are poly(ADP-ribosylated) to higher specific activity than histones; (c) there are significant differences between in vivo and in vitro studies on poly(ADP-ribosylation) of nuclear proteins in testis nuclei.

Adenosine Diphosphate Ribose↗