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Biomedical subjects

M B Jones

Publications and source records attributed to M B Jones.

At least 91 records · Page 5Linked to original sources
PubMed1987

Production of a growth factor(s) by fibroblasts from the lungs of ventilated premature baboons and oxygen-exposed adult hamsters.

Among the pathologic findings in infants succumbing to bronchopulmonary dysplasia are peribronchiolar and alveolar fibrosis. We examined the possibility that endogenously produced growth factors might contribute to these fibrotic changes through stimulation of fibroblast replication, with a resulting increase in collagen synthesis. We cultured fibroblasts from the lungs of prematurely delivered baboons and adult hamsters exposed to 100% oxygen and tested the media from these cells to see if they produced a factor(s) that was mitogenic to normal fibroblasts. We found that lung fibroblasts from baboons delivered prematurely at 140 days of gestation and ventilated for 6 days with 100% oxygen produced a factor(s) that supported fibroblast growth. A similar factor was also secreted by fibroblasts from normal term newborn baboon lungs and from the lungs of adult hamsters exposed to 100% oxygen for 4 to 8 days. Growth factor was not secreted by lung fibroblasts from 140-day non-breathing or 24-h-ventilated premature baboons, adult baboons, or hamsters not exposed oxygen. The growth-promoting substance is apparently a progression factor that is heat labile and inactivated by exposure to trypsin. These findings indicate that exposure of both the premature and adult lung to high concentrations of oxygen causes the elaboration of a growth factor that may induce fibroblast hyperplasia. This action may result in an increased production of connective tissue proteins and thereby contribute to the development of the fibrosis seen in bronchopulmonary dysplasia.

Animals↗
PubMed1987

Hemoglobin Chico [beta 66(E10)Lys----Thr]: a new variant with decreased oxygen affinity.

Hemoglobin Chico was discovered in an asymptomatic 3-year-old boy when a mild anemia was detected by a routine blood count. Affected individuals in three generations are also mildly anemic. The abnormal hemoglobin amounts to about 45% of the total. It separates from Hb A by cellulose acetate electrophoresis at pH 8.5 with a mobility similar to Hb J but does not separate in citrate agar at pH 6.2. Stability in isopropanol is slightly decreased. Its structure differs from the normal by the substitution of a threonyl residue for lysyl residue at position 66(E10) of the beta chain. The P50 of the oxygen equilibrium curve of whole blood at 37 degrees C was 38 torr compared with controls of 27 +/- 2 torr. The P50 binding studies of the isolated Hb Chico revealed a unique right shift of the equilibrium curve with an oxygen binding constant (1/P50) about half of normal. The remaining allosteric properties were essentially normal. This significant decrease in oxygen affinity appears to be due to changes in the heme region which result from the substitution of the normal beta 66 lysyl by the threonyl residue.

Anemia↗
PubMed1986

Mutations downstream of the polyadenylation site of a Xenopus beta-globin mRNA affect the position but not the efficiency of 3' processing.

In order to identify nucleotide sequences required for efficient and accurate polyadenylation of mRNA precursors, we have constructed a series of mutations in the X. laevis beta 1-globin gene and analyzed transcripts produced upon microinjection into Xenopus oocytes. Small deletion and linker replacement mutations, which lie in the region from 8 to 39 bp downstream of the AATAAA sequence and which effectively remove previously identified second components of the polyadenylation signal, do not greatly reduce the efficiency of processing, but in some cases alter the precise site of cleavage. We conclude that sequences downstream of the polyadenylation site affect the position of 3' RNA processing, but have minimal effects on its efficiency.

Animals↗
PubMed1986

Participation and sibship size in a skill-development program: a research note.

The behavior of interest in this study was participation or non-participation in a non-school skill-development program carried out in Ottawa, Ontario, for children living in a rent-to-income housing complex. Participant and non-participant children differed sharply only in sibship size; the larger the sibship from which a child came the greater the probability that he or she would participate. The basis for this relationship seems to have been a strong tendency for the probability of a child's participating to increase whenever a brother or sister in the same family participated.

Adolescent↗
PubMed1986

Hemoglobin Linkoping [beta 36 (C2) Pro----Thr] in a large Finnish family from Astoria, Oregon, USA.

Eleven members of a large Finnish family from Astoria, Oregon were studied because of an erythrocytosis. No abnormality was detected by the usual hemoglobin electrophoretic tests, but an abnormal variant was separated by reverse phase HPLC. All of the affected individuals have an increased oxygen affinity with a P50 for whole blood at 37 degrees C averaging 18 torr. Fifty percent of their hemoglobin was found to have a threonyl residue in place of the normal prolyl residue at position 36 (C2) of the beta globin chain. This abnormality is identical to Hb Linkoping which was recently reported in a Finnish man living in Sweden.

Aged↗
PubMed1985

Polyadenylation of the Xenopus beta 1 globin mRNA at a downstream minor site in the absence of the major site and utilization of an AAUACA polyadenylation signal.

We show that adult reticulocytes of Xenopus laevis produce two forms of the beta 1 globin mRNA that differ in their site of polyadenylation. The minor site of polyadenylation is located 46 nucleotides downstream of the major site and is used in approximately 1% of mRNA molecules. A fusion gene was constructed containing the promoter from the thymidine kinase gene of herpes simplex virus fused to the protein coding, 3'-noncoding and 3'-flanking sequences of the X. laevis beta 1 globin gene. When injected into the nuclei of Xenopus oocytes, transcripts of this fusion gene were accurately and efficiently spliced and polyadenylated. The proportion of fusion gene transcripts terminating at the major and minor polyadenylation sites after injection into oocytes was approximately similar to that found in reticulocytes. When the AATAAA sequence element upstream from the major site was deleted, the minor site was used with a high (greater than 90%) efficiency. Therefore, by comparing the ratio of polyadenylation at the major and minor sites, it is possible to determine the effect of sequence alterations at the major site. In a construct where the AATAAA polyadenylation signal was changed to AATACA a high proportion (35%) of transcripts continued to be polyadenylated at the major site. This suggests a surprisingly high degree of flexibility in the precise polyadenylation signal.

Animals↗
PubMed1984

A nuclear Overhauser enhancement study on the imino proton resonances of a DNA pentadecamer comprising the specific target site of the cyclic AMP receptor protein in the ara BAD operon.

A 500 MHz 1H-NMR study on a synthetic DNA pentadecamer comprising the specific target site of the cAMP receptor protein in the ara BAD operon is presented. Using pre-steady state NOE measurements, unambiguous assignments of all the imino proton resonances and associated adenine (H2) resonances are obtained. From the NOE data interbase pair interproton distances involving the imino and adenine (H2) protons are determined. It is shown that these distances are very similar to those expected for classical B DNA (RMS difference of 0.5 A), but are significantly different from those expected for classical A DNA (RMS difference of 1.1 A).

Adenine↗
PubMed1983

Nitrogen Turnover and Assimilation during Regrowth in Trifolium subterraneum L. and Bromus mollis L.

Subterranean clover (Trifolium subterraneum L. cv Woogenellup) and soft chess grass (Bromus mollis L. cv Blando) were grown in monocultures with (15)NH(4)Cl added to the soil to study nitrogen movement during regrowth following shoot removal. Four clipping treatments were imposed. Essentially all available (15)N was assimilated from the soil prior to the first shoot harvest. Measurements of total reduced nitrogen and (15)N contained within that nitrogen fraction in roots, crowns, and shoots at each harvest showed large, significant (P </= 0.001) declines in excess (15)N of crowns and roots in both species between the first and fourth harvests. There was no significant decline in total reduced nitrogen in the same organs over that period. Similar responses were evident in plants defoliated three times. The simplest interpretation of these data is that reduced nitrogen compounds turn over in plant roots and crowns during shoot regrowth. Calculations for grass and clover plants clipped four times during the growing season indicated that 100 to 143% of the nitrogen present in crowns and roots turned over between the first and fourth shoot harvest in both species, assuming nitrogen in those organs was replaced with nitrogen containing the lowest available concentration of (15)N. If other potential sources of nitrogen were used for the calculations, it was necessary to postulate that larger amounts of total nitrogen flowed through the crown and root to produce the measured dilution of (15)N compounds. These data provide the first quantitative estimates of the amount of internal nitrogen used by plants, in addition to soil nitrogen or N(2), to regenerate shoots after defoliation.

Journal Article↗
PubMed1983

Variability in nutrient intake in a 28-day period.

This study of food logs showed that although individual intake varied widely, there were no significant differences in the intake of energy or seven selected nutrients from week to week over a four-week period. With the exception of protein, there was no difference attributable specifically to the day of the week. Thus, it is concluded that 7-day records most accurately reflect intake over periods of up to 28 days. A 4-day record, covering a weekend (Friday through Monday), also correlates well with information collected for 7, 14, and 28 days.

Adult↗
PubMed1982

Television computer games: a 'new look' in performance testing.

Work at the Naval Biodynamics Laboratory aims at developing a battery of performance evaluation tests for environmental research (PETER). Because repeated-measures designs are virtually universal in environmental studies, the paradigm focuses on stabilisation with practice; thus far, over 50 tasks have been studied. The present report describes how five computerized video games fare as performance tests. The tasks were performed for 3 weeks each, in the same order, by the same subjects. The results show that four out of the five games meet all criteria satisfactorily and one does not, a favorable showing for the video games in comparison with conventional tests of either the paper-and-pencil or apparatus types. In terms of availability, equipment reliability, expense, and other practical considerations, the video games have many advantages. It is concluded that video games have considerable promise for performance testing and other applied contexts.

Adult↗
PubMed1981

Clinical value of serum bile acid levels in chronic hepatitis.

A prospective study was undertaken to determine if individual serum bile acid (SBA) levels are clinically useful in differentiating patients with asymptomatic chronic active hepatitis (CAH) from patients with chronic persistent hepatitis (CPH). Fasting and postprandial SBA levels were obtained from 16 patients with CAH, 12 with CPH, and 18 control subjects. Levels of cholylglycine (CG) and total cholic acid conjugates (CCA) were determined by radioimmunoassay. Alanine aminotransferase (ALT) levels were also obtained from each subject. There were no significant differences in the mean fasting and 3-hr postprandial CG or CCA levels between the CPH group and the control subjects. The mean fasting and 3-hr CG and CCA levels were significantly higher for the CAH group than the CPH group (P less than 0.05 for each comparison). A combination of the 3-hr postprandial CG and CCA levels with the ALT levels resulted in a better separation of the two groups. All patients with CAH had either a 3-hr CCA level of 200 micrograms/dl, a 3-hr CG level of 170 microgram/dl, or an ALT level of 120 IU/liter. Using these values, only patients with CPH were misclassified as having CAH, and no control subject reached any of these levels. Although the differences obtained were statistically significant, the separation based on a combination of CG, CCA, or ALT levels may have been fortuitous. Nevertheless, these data suggest that postprandial serum bile acid levels may have clinical utility in identifying patients with asymptomatic chronic hepatitis who are likely to have CAH.

Adult↗
PubMed1981

Multifocal eosinophilic granuloma involving the common bile duct: histologic and cholangiographic findings.

The multifocal eosinophilic granuloma syndrome (Hand-Schüller-Christian disease) is characterized histologically by focal accumulations of histiocytes and eosinophils. The clinical manifestations of this syndrome reflect the site and extent of these focal accumulations which are usually found in membranous bone, skin, and lung. Significant hepatobiliary disease due to this disorder has not been previously described. We are reporting an adult female with the multifocal eosinophilic granuloma syndrome who developed a mixed histiocytic and eosinophilic infiltration of the common bile duct which resulted in obstructive jaundice. Therapeutic attempts have failed to reverse this process, and the patient has shown progressive intrahepatic biliary tract destruction.

Adult↗