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Biomedical subjects

R W Parsons

Publications and source records attributed to R W Parsons.

At least 37 records · Page 2Linked to original sources
PubMed1993

Breast cancer in Western Australia in 1989. I. Presentation.

This study was designed as a population-based study of all cases of breast cancer diagnosed in Western Australia (WA) in 1989. Cases were identified from the State Cancer Registry and from computerized hospital inpatient records. Data were obtained from the records of surgeons and oncologists managing the patients, hospital medical records, and pathology and cytology reports. A total of 701 histologically proven tumours were documented in 692 women. Of these 6.8% were not known to the State Cancer Registry. Two-thirds (68%) of tumours were first detected by the woman herself, 11% were found by a doctor and 11% were detected by mammographic screening. Stage I tumours accounted for 40% of tumours and Stage II 39%. The estimated lifetime risk of a WA woman developing at least one malignant breast tumour is 10%. Passive surveillance based upon a legal obligation on doctors to notify cases of cancer may be resulting in a significant under-estimation of the incidence of cancer in WA. Mammographic screening played only a small role in the detection of breast cancer in WA in 1989, but its contribution and the proportion of stage I tumours should both increase as a population-based mammographic screening programme is established. This survey will provide a yardstick against which changes can be measured. Eighty-four per cent of tumours presently occur in women who would have access to mammographic screening although only 44% occur in the 50-69 age bracket that is to be actively recruited. The lifetime risk of breast cancer in WA women is greater than has been appreciated previously.

Adult↗
PubMed1993

Breast cancer in Western Australia in 1989. II. Diagnosis and primary management.

This study was designed as a population-based study of all cases of breast cancer diagnosed in Western Australia (WA) in 1989. Cases were identified from the State Cancer Registry and from computerized hospital inpatient records. Data were obtained from the records of surgeons and oncologists managing the patients, hospital medical records and pathology and cytology reports. A total of 701 tumours in 692 women were treated by 105 different surgeons of whom 25 saw 10 or more cases. Over 70% were proven by cytology or biopsy within 2 weeks of presentation to a doctor. The first diagnostic investigation was fine needle aspiration in 45%, open biopsy in 28% and diagnostic mammogram in 24.4%. A definitive procedure involving breast conservation was performed in 31.3% of patients with operable tumours; 35.6% of those under 50 years of age. If axillary dissection or sampling was part of such treatment, 93.5% of those under 50 years and 75% of those 50 years and over had radiotherapy to the residual breast. Although less than one-third of patients were referred to a medical oncologist almost a half had adjuvant systemic therapy (92% of node positive and 23% of node negative patients). Tamoxifen was prescribed as part of adjuvant therapy in 93% of those over 50 years and cyclophosphamide, methotrexate and 5-fluorouracil in 71% of those under 50 years. Less than 10% of patients treated with mastectomy and axillary dissection had postoperative radiotherapy to the chest wall and drainage areas. The patterns of care of patients with breast cancer in WA prior to the introduction of population-based mammographic screening have been established.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Changing patterns of medical treatment in acute myocardial infarction. Observations from the Perth MONICA Project 1984-1990.

TYPE OF STUDY: Descriptive study of trends in the drug therapy for acute myocardial infarction. SETTING: Population-based register of acute coronary events compiled for the years 1984 to 1990 in the course of the Perth MONICA project. CASES: 5294 cases meeting clinical criteria for acute myocardial infarction. RESULTS: Striking changes were seen in the use of aspirin before admission to hospital (from 4% to 18%). During the stay in hospital the use of beta-blockers increased steadily from 52% to 76%, while the use of aspirin increased 3.5-fold from 25% to 88% and the use of streptokinase increased 13.5-fold from 2.4% to 32.4%. The proportion of patients prescribed beta-blockers on discharge from hospital increased from 46% to 65% and that for aspirin rose from 16% to 83%. There were also major relative increases in the use of lipid-lowering agents and declines in the use of antiarrhythmic drugs. CONCLUSION: These trends in the pharmacological management of myocardial infarction mirror the emerging evidence from clinical trials, although the increases in the use of certain types of drugs antedated publication of the results of major randomised studies. The changes in therapy would partly explain observed improvements in case fatality and may have contributed to the decline in coronary mortality observed in the Perth community.

Adrenergic beta-Antagonists↗
PubMed1992

Class III antiarrhythmic activity of novel substituted 4-[(methylsulfonyl)amino]benzamides and sulfonamides.

The synthesis and Class III antiarrhythmic activity of a series of 4-[(methylsulfonyl)amino]benzamides and sulfonamides are described. Selected compounds show a potent Class III activity and are devoid of effects on conduction both in vitro (dog Purkinje fibers) and in vivo (anesthetized dogs). Compounds having a 2-aminobenzimidazole group were found to be the most potent, and one compound having this heterocycle (5, WAY-123,398) was selected for further characterization. Compound 5 was shown to have good oral bioavailability and a favorable hemodynamic profile to produce a 3-fold increase of the ventricular fibrillation threshold and to terminate ventricular fibrillation, restoring sinus rhythm in anesthetized dogs. Voltage-clamp studies in isolated myocytes show that 5 is a potent and specific blocker of the delayed rectifier potassium current (IK) at concentrations that cause significant prolongation of action potential duration.

Action Potentials↗
PubMed1992

Effects of WAY-123,398, a new class III antiarrhythmic agent, on cardiac refractoriness and ventricular fibrillation threshold in anesthetized dogs: a comparison with UK-68798, E-4031, and dl-sotalol.

Previous studies in isolated ventricular myocytes showed that WAY-123,398 is a selective blocker of the delayed rectifier K+ current (IK). In this report, we studied the electrophysiological and hemodynamic effects of WAY-123,398 in open-chest anesthetized dogs. WAY-123,398 prolonged atrial and ventricular refractoriness without affecting conduction; WAY-123,398 was as effective as UK-68798, E-4031, and dl-sotalol, but less potent than UK-68798 and E-4031. The increase in atrial refractoriness was approximately twice as large as the ventricular increase with all compounds. The hemodynamic effects of WAY-123,398 were similar to those of UK-68798; at the ED20 for increasing ventricular refractoriness, WAY-123,398 did not affect the mean arterial pressure and decreased the heart rate by 20%. In a different series of experiments, all four compounds produced large and comparable increases in the ventricular fibrillation threshold in anesthetized dogs; WAY-123,398 and UK-68798 induced defibrillation and restoration of sinus rhythm in two of six dogs each and E-4031 in one of six dogs. No episodes of drug-induced restoration to sinus rhythm were observed in dogs treated with sotalol or vehicle. In conclusion, WAY-123,398 is an effective Class III agent without Class I actions and with a favorable hemodynamic profile.

Anesthesia↗
PubMed1991

Synthesis and selective class III antiarrhythmic activity of novel N-heteroaralkyl-substituted 1-(aryloxy)-2-propanolamine and related propylamine derivatives.

The synthesis and biological evaluation of a series of novel 1-(aryloxy)-2-propanolamines and several related deshydroxy analogues are described. Compounds 4-29 were prepared and investigated for their class III electrophysiological activity in isolated canine Purkinje fibers and in anesthetized open-chest dogs. None of these compounds showed any class I activity. On the basis of the in vitro data, structure-activity relationships for the series are discussed. Two compounds, N-[4-[2-hydroxy-3-[methyl(2-quinolinylmethyl)amino] propoxy]phenyl]methanesulfonamide (12,WAY-123,223) and N-[2-[[methyl[3-[4-[(methylsulfonyl)amino]phenoxy]propyl] amino]methyl]-6-quinolinyl]-methanesulfonamide (24, WAY-125,971) were identified and characterized as potent and specific class III antiarrhythmic agents in vitro and in vivo. Compound 12 was found to be orally bioavailable, to produce large increases of ventricular fibrillation threshold (VFT), and, in some instances, to restore sinus rhythm from ventricular fibrillation in anesthetized open-chest dogs at a dose of 5 mg/kg (iv). The enantiomers of 12 (i.e., 13 and 14) were synthesized and were found to exhibit similar electrophysiological effects in the Purkinje fiber screen. Compound 24, a propylamine analogue with potency and efficacy comparable to those of UK-68798 (2) and E-4031 (3), was studied in voltage-clamp experiments (isolated cat myocytes) and was found to be a potent and specific blocker of the delayed rectifier potassium current (IK).

Animals↗
PubMed1991

The benefits of beta-blockade at the time of myocardial infarction.

Data from the World Health Organization Monitoring Trends and Determinants in Cardiovascular Disease (WHO MONICA) project, collected in Perth, are described. Patients taking a beta-blocker at the time of onset of myocardial infarction are a high-risk group, but univariate analysis of the data showed that the overall survival of patients on beta-blockers at 28 days was the same as for those not taking beta-blockers. A multiple logistic regression model analysis showed that the patients treated with beta-blockers had a survival advantage at 28 days, with a relative risk of death of 0.5. The mechanism of benefit is unclear. It does not appear to be an anti-arrhythmic effect, because beta-blockers did not affect survival in the first 24 h following a myocardial infarction, nor did they affect ventricular fibrillation. The effect may be due to a reduction in myocardial necrosis. Furthermore, an analysis of the incidence of coronary disease and type of drugs prescribed in Perth has indicated that beta-blockers may be contributing to a decrease in mortality due to coronary events.

Adrenergic beta-Antagonists↗
PubMed1991

Characteristics of new patients at Illinois cleft palate teams.

The Illinois Association of Craniofacial Teams (IACT) surveyed all new patient visits to member teams in an effort to assess the needs of patients in Illinois. The survey determined the number of patients, their age at initial visit, the location and status of their defect, and their history of team visits. Four hundred eighty new patient visits were recorded. The number of patients was substantially lower than expected, and the large majority of older children seeing a team for the first time had repaired defects. It is concluded that the main opportunity for improving the quality of care for patients with clefts in Illinois may be in increasing the use of cleft palate teams.

Age Factors↗
PubMed1990

Association of sleep apnoea with myocardial infarction in men.

To examine the hypothesis that sleep apnoea is a risk factor for ischaemic heart disease, overnight polysomnography was performed in 101 unselected male survivors of acute myocardial infarction (MI) aged less than 66 yr and in 53 male subjects of similar age without evidence of ischaemic heart disease. The apnoea index (AI, number of apnoea episodes per hour of sleep) was 6.9 (SEM 1.2) in the MI patients versus 1.4 (0.3) in the control subjects. After adjustment for age, body mass index, hypertension, smoking, and cholesterol level, multiple logistic regression analysis identified the top quartile of AI (greater than 5.3) as an independent predictor of MI patients. The relative risk for myocardial infarction between the highest and lowest quartiles of AI was 23.3 (95% confidence interval 3.9-139.9).

Adult↗
PubMed1990

Reduced risk of death at 28 days in patients taking a beta blocker before admission to hospital with myocardial infarction.

OBJECTIVE: To see whether patients taking an oral beta blocker at the time of admission to hospital with myocardial infarction have a reduced risk of death at 28 days. DESIGN: Retrospective analysis of data collected on patients admitted over four years. SETTING: Community based study. PATIENTS: 2430 Consecutive patients living in the Perth statistical division admitted to hospital with myocardial infarction during 1984-7. MAIN OUTCOME MEASURE: Survival at 28 days among patients taking a beta blocker at onset of myocardial infarction. RESULTS: Patients were grouped into those who were and were not taking a beta blocker at the time of admission. Though patients taking a beta blocker were older and more likely to have a history of myocardial infarction, angina, or hypertension, the overall mortality at 28 days was similar in the two groups. A logistic regression model used to adjust for factors predictive of cardiac death at 28 days confirmed that patients taking a beta blocker at the time of admission had a significantly reduced risk of death (relative risk 0.50; 95% confidence interval 0.34 to 0.76). Though the incidence of fatal ventricular fibrillation was similar in the two groups, mean peak creatine kinase activity was significantly lower in the beta blocker group. CONCLUSIONS: These data support the value of long term use of beta blockers in patients at risk of myocardial infarction. They suggest that patients taking these agents before admission to hospital with myocardial infarction have a significant survival advantage at 28 days, which may be due to a reduction in infarct size.

Adrenergic beta-Antagonists↗
PubMed1988

Survival after a second episode of toxic epidermal necrolysis.

Toxic epidermal necrolysis resulting from severe hypersensitivity to medication has a reported mortality of up to 66%. A patient surviving two episodes with more than a 50% skin loss is unprecedented in the medical literature. Mortality has been associated with many factors, including delayed reepithelialization, persistent skin slough, coagulopathy, severe hypoproteinemia, and sepsis. It may be possible to decrease morbidity and mortality by preventing the shearing of epidermis, thereby limiting the denuded areas. This case report describes the successful management of our patient's second episode of toxic epidermal necrolysis. The treatment of this patient in our specialized burn center consisted of careful fluid and electrolyte management, nutritional support, standard topical antimicrobials, and new modalities of local wound management.

Adult↗
PubMed1987

Hidradenitis suppurativa: patient satisfaction with wound healing by secondary intention.

Ariyan and Krizek, in 1976, reported on three patients with perineal hidradenitis suppurativa who, following excision, achieved satisfactory closure allowing spontaneous wound healing by secondary intention. We have used this approach and have considered it very satisfactory from the surgeon's point of view. We now report from the point of view of patients and review the records of 20 consecutive patients with perineal hidradenitis treated by excision and secondary healing. Surgical results and patient satisfaction were assessed 1 year following complete wound closure. All patients reported minimal inconvenience and interruption of daily activities from this method of management. Analgesic requirements were minimal, and little reinforcement was necessary to maintain vigorous wound care. Uncomplicated wound closure was uniformly achieved with unrestrictive, stable scars providing long-term relief of this disabling disease. Two patients expressed dissatisfaction as a result of a new onset of disease in previously uninvolved and therefore unresected apocrine tissue. With this exception, patient satisfaction has been great and hospitalization time and costs reduced.

Adolescent↗
PubMed1984

Ectropion and epiphora in McArdle's syndrome.

Ectropion is unusual in young individuals. Recently, we treated a 19-year-old male college student for epiphora due to bilateral ectropion associated with McArdle's syndrome, a myophosphorylase deficiency. To our knowledge, there have been no previous reports of ectropion and epiphora as a result of this rare glycogen-storage disease.

Adult↗
PubMed1984

Skin grafting herpetic ulcers.

Recurrent and chronic herpetic skin ulcers are associated with the persistence of virus in the dorsal root ganglia serving the respective dermatomes. Descriptions of surgical approaches to control herpetic skin disease have recently appeared in the medical literature. We report the successful excision and skin grafting of chronic genital ulcers. Our subsequent animal studies support our expectations that potential seeding and reinfection of the grafted skin can occur following graft reinnervation. This problem must be watched for following grafts of herpetic ulcers in humans.

Abdomen↗
PubMed1984

Acceleration of capsule formation around silicone implants by infection in a guinea pig model.

Fibrous capsules surrounding silicone implants were investigated in a new guinea pig model to delineate some of the factors leading to capsular contracture. Both the implant surfaces and tissue capsules were examined by light and scanning transmission electron microscopy (STEM + SEM) with x-ray energy spectroscopy (XES). The capsular tissues were qualitatively similar to those recovered clinically, showing dense parallel collagen deposits, fibroblasts, myofibroblasts, macrophages, and foreign-body giant cells. Silicone was positively identified within intercellular vacuoles and the rough endoplasmic reticulum of macrophages by XES. Tissue recovered from the capsules that surrounded implants that were contaminated with S. aureus presented a qualitatively similar histologic spectrum. The contaminated specimens did show an accelerated response. SEM showed a cellular invasion of the silicone envelopes. We conclude that the model accurately simulates the clinical situation and suggests that immune mechanisms may play a key role in capsular contracture.

Animals↗
PubMed1983

Biocompatibility of silicone implants.

Polydimethylsiloxane has been considered immunologically inert, and previous work seems to have established that the production of circulating antibodies does not occur in response to its implantation. We have investigated the possibility of a cellular immune response to implanted silicone. We have observed histologically that the cellular response to polydimethylsiloxane in sensitized guinea pigs is consistent with a cellular immune reaction. Further studies with EM and XES have demonstrated intracellular silicon in the Golgi apparatus, rough endoplasmic reticulum, and at both ends of cytoplasmic bridges between macrophages and lymphocytes. All of these findings fit with the hypothesis that the cells are processing a silicon-containing complex as an antigen. Finally, macrophage migration inhibition studies have shown evidence of a cellular immune phenomenon. Further studies are planned to characterize the nature of the sensitizing complex and to attempt to confirm the migration inhibition studies in vivo.

Animals↗
PubMed1983

Analysis of the surface morphology of recovered silicone mammary prostheses.

The surfaces of 11 silicone mammary prostheses were examined by scanning electron microscopy (SEM) and energy dispersive x-ray spectrography (XES). Three of the prostheses were recovered from clinical cases and eight from guinea pig models. The surfaces of the prostheses were covered with an investing film and by 2- to 5-microns spheres aggregated in 40- to 200-microns-wide patches. The embeddedded spheres were blebbed and surrounded by pits. X-ray energy spectrography showed high levels of sodium, chlorine, and potassium. It is concluded from this evidence that phagocytic cells embed themselves within the envelope, perhaps by an immune-mediated phagocytic process.

Animals↗