Search PubMed⌕ Search

Biomedical subjects

R Jones

Publications and source records attributed to R Jones.

At least 847 records · Page 47Linked to original sources
PubMed1984

Cloning and organisation of some genes for nitrogen fixation from Azotobacter chroococcum and their expression in Klebsiella pneumoniae.

By DNA hybridisation, restriction fragments of genomic DNA from Azotobacter chroococcum and A. vinelandii bearing sequences homologous to Klebsiella pneumoniae nitrogenase structural genes were detected. These were different in the two species and inconsistent with the arrangement of the homologous sequences as a contiguous cluster of unique genes. The use of a DNA probe specific for nifH showed that in A. chroococcum two nifH-like sequences were present in the genome. From gene libraries for A. chroococcum, several recombinant cosmid clones bearing nif genes were identified and physically mapped. One copy of the nifH-like sequences was closely linked to nifD and K, the order of genes being as for K. pneumoniae. This cluster was sub-cloned into the broad host-range vector pKT230. The resultant plasmid complemented for C2H2-reduction but not growth in N2 several Nif- mutants of A. vinelandii and K. pneumoniae and also abolished growth in N2 in Nif+ parents. The inhibition was ascribed to a short region adjacent to nifH, which probably corresponds to the promoter as its inhibitory affects were alleviated by provision of K. pneumoniae nifA in multiple copies. 3 sizes of transcripts are produced from the region containing nifH and nifD of A. chroococcum in cultures derepressing for nif. A region bearing homology to a fragment of the K. pneumoniae nif cluster bearing nifV was identified 15 Kb away from nifHDK in A. chroococcum however the order of genes is probably similar to that of K. pneumoniae.

Azotobacter↗
PubMed1984

Technetium-fibrinogen lung scanning in canine lung contusion.

To detect experimentally induced acute lung contusion in anesthetized dogs, serial radionuclide images of the lung were recorded following intravenous infusion of 99mTc-labelled human fibrinogen (Tc-HF). The accumulation of Tc-HF in canine lungs was serially quantitated for up to 20 hours after lung contusion. A contusion (#1) was produced in one lung, Tc-HF was injected IV after 15 minutes, and 75 minutes later a contralateral lung contusion (#2) was produced in a series of 14 dogs. At autopsy the excised lungs were scanned, sectioned, and counted for radioactivity. Radiolabelled fibrinogen accumulated within 2-4 minutes of contusion #2 and remained stable over the next 20 hours in 14 dogs; contusion #1 was barely visible in four dogs. Lung Tc-HF activity in the central region of contusion #2 remained sixfold higher than in normal lung tissue. These data suggest that following lung contusion, fibrinogen deposition occurs rapidly and remains stable over a 20-hour interval of observation.

Animals↗
PubMed1984

A preoperative chymopapain sensitivity test for chemonucleolysis candidates.

A fluorescence enzyme immunoassay (ChymoFAST test) for the quantitation of chymopapain-specific IgE antibody concentration in human serum is described. The IgE antibody is recognized as the major immunologic mediator for anaphylactic reactions. Serum chymopapain-specific IgE levels serve as an objective screening method for identifying patients most likely to tolerate chymopapain, thereby minimizing associated risks. Preoperative sera obtained from 11,658 chemonucleolysis candidates were tested, of which 0.94% (110/11,658) were found to be positive. Good predictive values for both positive and negative findings are evident based on 4776 postmarketing surveillances obtained from the surgeons.

Antibody Specificity↗
PubMed1984

Chymopapain-induced hypersensitivity following chemonucleolysis.

This study describes the changes in chymopapain-specific IgE antibody levels in patients following chemonucleolysis with Chymodiactin. Using the ChymoFAST method, chymopapain-specific IgE values were studied in 91 patients prior to and for 2 months post-Chymodiactin chemonucleolysis. A total of 8.8% (17/91) developed IgE levels greater than or equal to 0.06 IU/ml. Those patients with detectable IgE levels prior to chemonucleolysis were more likely than those with nondetectable preinjection levels (36.4% versus 4%) to develop chymopapain-specific IgE levels greater than or equal to 0.06 IU/ml.

Antibody Specificity↗
PubMed1984

Genome size and complexity in Azotobacter chroococcum.

All of eight strains of Azotobacter chroococcum examined contained between two and six plasmids ranging from 7 to more than 200 MDal in size. Strain MCC-1, a derivative of NCIMB 8003, was cured of various of the four largest of its five plasmids and the phenotypes of the strains compared. all fixed nitrogen and exhibited uptake hydrogenase activity. No differences were observed in carbon source utilization or antibiotic, heavy metal or UV resistance. The genome sizes of two strains of A. chroococcum were determined by two-dimensional electrophoresis. Strain CW8, an isolate from local soil containing two small plasmids of 6 and 6.5 MDAl contained unique DNA sequences equivalent to 1.78 x 10(6) (+/- 20%) bp (1.2 x 10(9) Dal). In strain MDC-1, a derivative of MCC-1, containing a 190 MDal and 7 MDal plasmid, the genome size was 1.94 x 10(6) (+/- 20%) bp. In exponential batch cultures, both contained 20 to 25 genome equivalents per cell. MCD-1 exhibited complex UV kill kinetics with a marked plateau of resistance; CW8 showed a simple response inconsistent with the possibility of organization of its DNA into identical chromosome copies capable of independent segregation.

Azotobacter↗
PubMed1984

Platelet impedance aggregation in whole blood and its inhibition by antiplatelet drugs.

Platelet aggregation was studied in citrated whole blood by an electrical impedance method. Blood samples from normal volunteers were studied with the aim of finding a suitable method for the routine study of samples from patients. An erratic tracing and low maximum aggregation were seen in samples with a high normal haematocrit. Optimal aggregation was seen when blood was diluted to a haematocrit of .300; isotonic saline was a better diluent than platelet poor plasma. No appreciable differences were seen when the platelet count was diluted down to 50 X 10(9)/l, after which there was a progressive reduction in response. Dose response curves were obtained, and normal ranges for ADP, collagen, and sodium arachidonate were determined. Acetylsalicylic acid had a more pronounced effect on ADP aggregation than on collagen. Prostacyclin (Epoprostenol) and the synthetic prostacyclin analogue ZK 36,374 both showed dose dependent inhibition of aggregation, but the duration of effect of the latter was much longer (greater than 6 h).

Adenosine Diphosphate↗
PubMed1984

Short-term memory for duration of movement.

This study examined the short-term retention characteristics of temporal information about visually guided movements. Subjects attempted to recall a preselected movement of a particular duration either immediately or after an unfilled or filled retention interval. Subjects did not benefit from an opportunity to rehearse information about duration of movement over the interval. This finding supports a decay model of forgetting for temporal information about visually guided movements.

Adult↗
PubMed1984

Surgical experience following percutaneous transluminal coronary angioplasty.

Percutaneous transluminal coronary angioplasty (PTCA) was attempted in 600 patients, 97 of which were considered unsuccessful. Review of our surgical experience in a large series of these procedures helps to confirm some facts regarding the unique interaction between these two modalities of myocardial revascularization. Serious complications are still relatively common, even when PTCA is performed in centers with broad experience. While emergency operation is not required in all major complications, about 7% of patients need immediate surgical intervention, which is usually performed on unstable patients, and thus associated with increased morbidity and mortality. The combined incidence of major complications, such as coronary dissection, occlusion, and spasms, still approaches 20% of attempts. In contrast to other studies, surgical mortality and morbidity do not appear to be higher in our series of operations on patients with complicated PTCA than in coronary bypass operations in general. This fact may attest to our practice of alerting all surgical services in anticipation of problems. Our short complication-to-operation completion time, averaging 123 minutes, may be partially responsible for the good results. We conclude that standby open-heart services for PTCA are warranted in most hospitals; however, it should not be performed in hospitals without surgeons who are experienced in the practice of open-heart surgery.

Journal Article↗
PubMed1984

Pulmonary artery remodeling and pulmonary hypertension after exposure to hyperoxia for 7 days. A morphometric and hemodynamic study.

This study shows by morphometric and hemodynamic techniques that exposure to hyperoxia at normobaric pressure causes rapid structural remodeling of rat pulmonary arteries and pulmonary hypertension. After 7 days of 90% O2, pulmonary artery cross-sectional area is reduced by a striking loss of intraacinar arteries (control, 13 +/- 1 sq mm; exposed, 8 +/- 1 sq mm; P less than 0.001), the ratio of arteries to alveoli being 4:100 in control rats and 2.5:100 after hyperoxia. The lumen of preacinar and intraacinar arteries is narrowed by a reduction of vessel external diameter (ED) and an increased medial wall thickness (MT). There is a significant reduction in the percent medial thickness [( 2 X 100 X MT]/ED) in both regions. The proportion of muscular and partially muscular intraacinar arteries increases at the expense of nonmuscular ones (P [chi 2] less than 0.01), and fully muscular arteries appear in the alveolar wall where they are not normally found. Intimal thickening occurs in 19% of alveolar duct and 34% of alveolar wall nonmuscular arteries. Right ventricular hypertrophy occurs, the ratio of the left ventricle plus the septum to the right ventricle being significantly reduced (control, 4.07 +/- 0.26; exposed, 3.23 +/- 0.10; P less than 0.02). After 3 days of 87% O2, pulmonary artery pressure is still normal (17.0 +/- 0.9 mmHg) but after 7 days it is significantly increased (26.2 +/- 0.9 mmHg; P less than 0.01), as is pulmonary vascular resistance (control, 0.033 +/- 0.003; exposed, 0.065 +/- 0.015 U/kg; P less than 0.05). Return to air breathing (after 7 days at 87% O2) causes pulmonary vasoconstriction and a further rise of the pulmonary artery pressure (to 38.3 +/- 3.3 mmHg after 60 minutes).

Animals↗
PubMed1984

The development of a model of subacute lung injury after intra-abdominal infection.

Acute respiratory failure in humans often follows extrathoracic sepsis. The purpose of this study was to determine the effect of repeated episodes of intra-abdominal sepsis over several weeks on the structure and function of rat lung. Intermittent peritonitis and a bacteremia of Escherichia coli and Bacteroides fragilis were produced by weekly intra-abdominal implants of gelatin capsules containing these organisms (3.0 +/- 1.0 X 10(7) and 5.0 +/- 1.0 X 10(7) colony-forming units/ml, respectively; mean +/- SEM). After 4 weeks alveolar walls were thickened and cellular with focal areas of alveolar space consolidation: circulating polymorphonuclear leukocytes were increased (12.2 +/- 1.2 to 19.9 +/- 2.0 X 10(3)/mm3; p less than 0.05), as were plasma levels of 6-keto-PGF1 alpha (0.56 +/- 0.08 to 1.02 +/- 0.18 ng/ml; p less than 0.01). After 8 weeks the capillary bed was dilated and the alveolar walls and ducts appeared less cellular but showed fibrosis: The WBC count had increased to 25.5 +/- 1.0 X 10(3) (p less than 0.01). After 4 or 8 weeks of intermittent sepsis there was no increase in the pulmonary artery pressure or vascular resistance or any change in arterial oxygen tension, plasma thromboxane beta 2 level, or platelet count. We conclude that repeated bouts of sepsis and bacteremia in the rat cause progressive injury to lung alveoli without evidence of altered blood gas tensions or pulmonary hemodynamics.

6-Ketoprostaglandin F1 alpha↗