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Biomedical subjects

M Jones

Publications and source records attributed to M Jones.

At least 775 records · Page 43Linked to original sources
PubMed1984

Modification by the Hancock T6 process of calcification of bioprosthetic cardiac valves implanted in sheep.

The effectiveness of the T6 process (surfactant treatment) to decrease calcification of porcine aortic valvular (PAV) and bovine pericardial (BPV) bioprostheses was investigated. Morphologic and biochemical studies were made of standard and T6-treated PAVs and BPVs that had been implanted for a mean of 20 weeks in the tricuspid position in young sheep. Gross, radiographic, histologic and ultrastructural observations showed that the calcific deposits were less severe in T6-treated (n = 9) than in standard PAVs (n = 7), but were similar in severity in T6-treated (n = 6) and standard BPVs (n = 7). This was confirmed by results of quantitative analyses for calcium in half of each cusp of each explanted valve. Because these results showed large differences in standard deviations in the 4 groups of sheep, natural logarithmic and square-root transformations were used for statistical comparisons. The mean calcium content (milligrams of calcium per gram of dry tissue) of standard PAVs (111 +/- 53) was greater than that of T6-treated PAVs (11 +/- 3) (p = 0.0037). The calcium content of T6-treated PAVs was lower than that of T6-treated BPVs (96 +/- 26) (p = 0.031). However, the calcium content of standard BPVs (35 +/- 13) was not different from that of T6-treated BPVs or standard PAVs. Thus, under conditions of relatively short-term implantation in the sheep model, the T6 process is useful for decreasing the extent of calcification in PAVs, but not in BPVs.

Animals↗
PubMed1984

A comparison of attitudes toward orthodontic treatment in British and American communities.

Utilization of orthodontic services may be influenced as much by the social and cultural setting as by objective criteria. The public's assessment of dental irregularity and its perceptions of the psychosocial implications of malocclusion may be critical factors in the utilization of available services. To test these assumptions, two communities with historic differences in the availability and utilization of orthodontic services were selected as survey sites (Lexington, Kentucky, and Cardiff, Wales). Three-hundred eighty-five sixth grade children (11 to 12 years of age) and 123 of their parents were interviewed concerning dental esthetics, treatment need, and knowledge about, attitudes toward, and value placed on orthodontic treatment. Although the Lexington respondents had greater personal and indirect knowledge about such services, they did not have more positive perceptions about treatment; nor did they value straight teeth more highly. There were no significant differences between the groups' judgement of dental esthetics or assessment of treatment need. The differences in utilization of services in the two communities could not be explained in terms of differences in attitude toward malocclusion and orthodontic treatment.

Adult↗
PubMed1984

A structural basis for variegating position effects.

Variegating position effects in Drosophila result from chromosome rearrangements where normal genes, having been placed next to heterochromatin, are inactivated in some cells but not in others, thereby producing a variegated tissue. We have determined that the euchromatic breakpoints for three variegating white mutants are clustered and lie approximately 25 kb downstream of the white structural gene. In each case the white locus is adjoined in the heterochromatin to a mobile genetic element. Satellite sequences are not involved. We also demonstrate that revertants of the variegating mutant, wm4, are reinversions that leave the initial wm4-heterochromatic junction intact so that some heterochromatin-derived sequences remain joined to white at its new location. These results suggest a simple model for understanding the structure of heterochromatic domains and how variegating position effects may arise.

Animals↗
PubMed1984

Results of early excision and grafting in hand burns.

A total of 658 admissions to the Burns Unit at the Royal Brisbane Hospital were reviewed over a 4-year period. During this time, 73 hand burns were treated. The policies of the Burns Unit regarding hand burns are detailed; and, where possible, early excision and grafting is performed. The results of these hand burns are discussed and indicate minimal requirements for reconstructive surgery. The most common reconstructive surgery needed was for web space release in 10 patients and excision of hypertrophic scar in 2 patients. It is concluded that early excision and grafting of hand burns is safe and practical, and combined with adequate splinting, exercise and pressure garments, gives good results and lessens hospital stay in patients with relatively small injuries. The duration of stay in hospital in patients with large burns is not due to the treatment of their hand burns, but to their overall large body surface area burnt.

Adolescent↗
PubMed1984

The effect of d-amphetamine and ephedrine on smoking attitude and behavior.

Using a double blind, randomized, latin square design, 17 light smokers and 6 heavy smokers were given three times per day doses of placebo, 5 mg amphetamine sulfate, 7.5 mg amphetamine sulfate, 25 mg ephedrine hydrochloride or 50 mg ephedrine hydrochloride. Compared to placebo, active drug produced a statistically significant drop in feeling of addiction to cigarettes (p = 0.022). Ephedrine was reported to be more effective than amphetamine (p = 0.046). Subjects reported similar changes in feeling of enjoyment of smoking. Active drug produced a statistically significant drop in the actual amount of tobacco smoked in heavy smokers (p = 0.028), but not in light smokers. Only two smokers were able to quit completely during the experiment, and one of those people resumed smoking after she stopped taking medication. Possible explanations of these findings are discussed.

Attitude↗
PubMed1984

Radionuclide evaluation of acute scrotal disease.

Technetium-99m sodium pertechnetate scintigraphy is an established method for evaluating organ perfusion and can be applied to the investigation of suspected testicular ischaemia due to acute torsion. One hundred and six consecutive scrotal investigations have been analysed qualitatively and quantitatively using a computer-based comparison of the perfusion slopes over each testis. Decreased vascularity on the symptomatic side only occurs in torsion and quantitative analysis is needed to detect it reliably. Increased vascularity on the symptomatic side can usually be detected qualitatively and occurs in orchitis, tumours, trauma and resolved torsion. Distinction between the causes of increased vascularity is aided by the clinical data. A halo of increased activity surrounding a relatively cold centre was seen in chronic torsion, some tumours and hydrocoeles. The test is both sensitive and specific for acute torsion but its usefulness is limited if it is not available at all hours. The test is useful, also, in confirming a diagnosis that does not require emergency operation and in identifying chronic torsion which is an indication for contralateral orchidopexy.

Acute Disease↗
PubMed1984

Oesophageal candidiasis and croup in a child with defective neutrophil motility.

Severe oesophageal candidiasis and croup due to involvement of the larynx developed insidiously in a girl aged 20 months. There had been delayed separation of the umbilical cord and repeated infections associated with a defect of neutrophil motility. The significance of the early clinical features was not fully appreciated and the diagnosis considered only when stricture of the oesophagus became evident. She was treated with oral ketoconazole 100 mg daily. After one month's treatment there was striking radiological improvement apart from the persistence of the oesophageal stricture. The croup resolved completely but there was only partial relief of dysphagia because of the residual stricture. We would emphasis that candidiasis should be anticipated and treated vigorously in children with such a defect of neutrophil motility.

Candidiasis↗
PubMed1984

Cardiac performance and myocardial blood flow in pigs with compensated right ventricular hypertrophy.

Compensated right ventricular hypertrophy (RVH), defined by a greater than 100% RV weight increase compared to 17 normal animals, was created in 17 young pigs by pulmonary arterial banding. RVH was associated with significant elevations (p less than 0.001) in RV peak dP/dt, RV stroke work, RV minute work and RV rate-pressure product compared to normal animals matched by body weight. RV peak dP/dt showed a positive correlation (p less than 0.001) with RV peak systolic pressure in normals; however, this relationship was lost in banded animals since progressively higher RV pressures were not associated with concomitant increases in RV peak dP/dt, thus, suggesting an intrinsic difference between right and left ventricles when working at systemic arterial pressures. Time to RV peak dP/dt became progressively longer (p less than 0.05) as RV weight increased in the RVH animals. When indices of cardiac work were normalized for RV weight, the RVH group could not be distinguished from normals suggesting that the performance per unit weight of RV muscle in RVH was unchanged. Total RV blood flow, measured by radioactive microspheres, closely followed (p less than 0.001) increases in RV mass in banded animals. Blood flow . g-1 muscle in RV and septal right side were unaltered in RVH; however, regional perfusion of the left ventricle (p less than 0.001) and septal right side were unaltered in RVH; however, regional perfusion of the left ventricle (p less than 0.001) and septal left side (p less than 0.02) increased significantly. There were regional variations in RV perfusion which were maintained in compensated RVH; stress (isoprenaline infusion) caused significant increases in blood flow to all regions of the heart in normal and RVH animals (p less than 0.001), but relative regional distribution was maintained. Our observations suggest a relationship between myocardial work and blood flow in RVH such that RV perfusion . g-1 is elevated to meet haemodynamic requirements once RV regional work . g-1 become greater than normal.

Animals↗
PubMed1984

Recovery of the hypothalamo-pituitary-adrenocortical axis in the rat after long-term dexamethasone treatment.

Male rats were treated for 14 days with dexamethasone (2.6 mumol/l in the drinking water) and killed at various times after withdrawal of the drug. Some animals were subjected to stress (ether or sham adrenalectomy) just before killing. The recovery of responsiveness of the components of the hypothalamo-pituitary-adrenocortical axis was assessed by measuring plasma and tissue concentrations of hormones, and the response of the tissue in vitro to appropriate stimuli. In vitro, bioactive corticotrophin-releasing factor (CRF) release in response to acetylcholine and adrenal corticosterone release in response to adrenocorticotrophin (ACTH) were significantly suppressed until 3 days after withdrawal. However, release of immunoreactive or bioactive ACTH in response to ovine CRF or hypothalamic extract did not return to normal until day 5. This was correlated with a reduction in pituitary immunoreactive ACTH content and bioactive plasma ACTH, which were suppressed until days 5 and 4, respectively. No change in hypothalamic immunoreactive CRF content could be detected after treatment, or after stress (ether or sham adrenalectomy) in either treated or control animals. Stress (ether) had no effect on the subsequent response of the anterior pituitary gland in vitro to ovine CRF. The large rises in plasma ACTH and adrenal corticosterone measured after stress (ether) in control animals were completely abolished after dexamethasone treatment and did not return to control values until 5 days after withdrawal. Therefore, it appears that after cessation of chronic dexamethasone treatment in the rat, the responsiveness of the hypothalamus and adrenal gland return to normal before that of the pituitary gland.

Adrenalectomy↗
PubMed1984

Reversal of left ventricular dysfunction after aortic valve replacement for chronic aortic regurgitation: influence of duration of preoperative left ventricular dysfunction.

Preoperative left ventricular systolic function is an important predictor of postoperative prognosis in patients with aortic regurgitation. Although left ventricular dysfunction is reversible after aortic valve replacement to a greater extent in patients with good preoperative exercise capacity compared with patients with impaired exercise capacity, not all patients with preserved exercise capacity demonstrate improved left ventricular function after aortic valve replacement. To determine the influence of duration of preoperative left ventricular dysfunction on postoperative reversal of left ventricular dysfunction, we studied 37 patients with aortic regurgitation who preoperatively had left ventricular dysfunction, defined as subnormal echocardiographic fractional shortening (less than 29%), and good preoperative exercise capacity, defined as completion of stage I of the NIH treadmill protocol without limiting symptoms. Eight patients were asymptomatic. In 11 patients left ventricular dysfunction was documented 18 to 57 months preoperatively (prolonged); in 10 patients left ventricular dysfunction developed in an interval of 14 months or less preoperatively (brief); in 16 patients duration of left ventricular dysfunction was unknown. Patients with brief vs those with prolonged left ventricular dysfunction did not differ with respect to severity of preoperative symptoms or exercise tolerance, echocardiographically determined left ventricular dimensions or fractional shortening (25 +/- 3% [SD] vs 25 +/- 3%), or radionuclide angiographic ejection fraction (42 +/- 5% vs 42 +/- 5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

A randomized study comparing chemotherapy alone with chemotherapy followed by radiotherapy in patients with pathologically staged IIIA Hodgkin's disease.

This paper reports the five-year follow-up (range, 1-8 years) of 56 patients with pathologic stage IIIA Hodgkin's disease randomized for chemotherapy alone or chemotherapy followed by radiotherapy to previous areas of disease (26 treated with mustine, vinblastine, procarbazine, and prednisolone [MVPP] alone, 30 with MVPP and radiotherapy). Of the 56 patients 53 (95%) achieved a complete remission with chemotherapy and of these only five (9%) have relapsed; three died of Hodgkin's disease. There was no improvement in relapse-free survival associated with the uses of radiotherapy following chemotherapy but in view of the small numbers of relapses and the excellent results following chemotherapy alone, a significant improvement could not be expected. The use of MVPP alone can be recommended as an alternative therapy for patients with stage IIIA Hodgkin's disease. This avoids both the physical and psychologic morbidity associated with the high relapse rate following extensive primary radiotherapy and the necessity of combined modality treatment for about half these patients. The question of whether radiotherapy should be given to areas of previous bulk following chemotherapy has not yet been answered in this trial which is continuing.

Adult↗
PubMed1984

Changes in distribution of the phases of mitosis in human tumor xenografts following drug treatment.

Distribution of individual mitotic phases in different human xenografts on nude mice showed significant changes after treatment with a range of drugs when compared with untreated controls. The total amount of mitoses in prophase significantly decreased in all responsive tumors while those in all other phases increased but in a very variable degree. There was some correlation in between the range of the mitotic phase distribution changes and the degree of tumor response to treatment.

Animals↗
PubMed1984

Relationship between melanogenesis, proliferative activity and response to chemotherapy of human melanoma xenografts.

Wide range of different drugs used in the cytotoxicity studies in an amelanotic human melanoma xenograft on nude mice showed a clear inverse relationship between melanogenesis and proliferation. Decreasing rates in proliferative activity estimated by mitotic answer expressed by phase distribution changes as well as by the tumor volume response to drug treatment were in direct relationship with increasing rates in the degree of melanogenesis expressed in percentage of melanin containing cells in histological specimens.

Animals↗
PubMed1984

The significance of discrepant Farr and Crithidia luciliae tests.

The most specific serological test for systemic lupus erythematosus (SLE) is the detection of anti-dsDNA antibodies by the Farr or Crithidia luciliae (CL) assay. Serological interpretation is difficult when these assays give discrepant results (i.e., one is positive and the other negative). In the present study 34 patients with discrepant results (18 CL positive Farr negative; 16 CL negative Farr positive) were reviewed to determine whether they fulfilled ARA criteria for SLE at presentation or at follow up 1-50 months (mean 15.8 months) later. Only 2 patients had SLE, both of whom fulfilled ARA criteria at presentation. Discrepant CL and Farr assays are associated with SLE uncommonly and rarely precede the development of clinical lupus.

Adult↗