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Biomedical subjects

G R Lewis

Publications and source records attributed to G R Lewis.

At least 19 recordsLinked to original sources
PubMed1995

Advances in partial denture ceramics.

Two techniques for incorporating bonded porcelain facings within metal partial dentures are described. In the first technique, porcelain is bonded to a metal framework constructed of bonding alloy. In the second technique, separate components are combined in a cast-on procedure to incorporate the mechanical properties of both bonding and framework alloys in one prosthesis. These techniques have enabled the successful treatment of patients in whom limited interocclusal space or parafunctional activity had led to failure of previous prostheses.

Acrylic Resins↗
PubMed1994

A denture replication technique following partial maxillectomy: a case report.

A variety of problems faces the prosthodontist attempting reconstruction of maxillary defects. There are various treatment options for patients requiring a partial maxillectomy and an obturator prosthesis. Reduced adaptability makes it difficult for the patient to learn to use a new appliance, unless existing skills can be employed. It is therefore helpful to reproduce familiar features of a patient's existing obturator, especially if this has been used successfully over a transition period.

Dental Prosthesis Design↗
PubMed1991

Treatment of primary hypercholesterolaemia with simvastatin. New Zealand multicentre evaluation.

OBJECTIVE: To assess the efficacy of simvastatin in a large patient cohort. DESIGN: In an open multicentre study, after a four week placebo phase, patients were treated with simvastatin for 24 weeks; a subgroup continued therapy for a further 24 weeks. Efficacy of simvastatin (a) with prolonged use over three years, and (b) in combination with bezafibrate was assessed in an open single site study. SETTING: Lipid or cardiology specialist hospital outpatient clinics. PATIENTS: For the open multicentre study, 228 patients with primary hypercholesterolaemia (total cholesterol level greater than 6.5 mmol/L) were recruited, of whom 224 met entry criteria and completed the study. Forty-seven of these patients continued therapy for one year. In the open single site study, 22 patients (with low density lipoprotein [LDL] cholesterol levels greater than 4.3 mmol/L) participated in studies of long term use (n = 9) or of combined therapy (n = 13). INTERVENTION: Therapy in the open multicentre study began with 10 mg of simvastatin per day, doubling to 20 mg after six weeks and then 40 mg after 12 weeks of therapy if total cholesterol levels persisted above 5.2 mmol/L. In the study of long term use, simvastatin (40 mg daily) was taken continuously over three years. In the study of combination therapy, bezafibrate (600 mg daily) was taken in addition to simvastatin (40 mg daily) for 10 months. MAIN OUTCOME MEASURES: Plasma lipid and lipoprotein concentrations. RESULTS: In the multicentre study, total plasma cholesterol levels were reduced by 32.8% from 9.11 +/- 1.84 (in mmol/L, mean +/- SD) to 6.12 +/- 1.25 (P less than 0.001), and LDL cholesterol levels by 41.4% from 6.90 +/- 1.92 to 4.04 +/- 0.31 (P less than 0.001). The effect of therapy was sustained in those patients continuing therapy to 48 weeks. The study of long term use found no significant attenuation of effect over three years of monotherapy. Combined simvastatin/bezafibrate therapy reduced the LDL cholesterol concentration by a further 19.9% (P less than 0.001) from levels achieved on simvastatin alone. CONCLUSIONS: Simvastatin is an effective, well tolerated lipid lowering drug, without significant attenuation of effect with prolonged use. Simvastatin plus bezafibrate appears to be a potentially useful drug combination.

Adult↗
PubMed1989

Comparison of lisinopril versus placebo for congestive heart failure.

A multicenter, randomized, double-blind assessment of 130 patients with congestive heart failure (New York Heart Association functional classes II to IV) was undertaken to assess the therapeutic efficacy of lisinopril, an angiotensin-converting enzyme inhibitor. All the subjects received concurrent therapy with digoxin and diuretics. Assessments performed periodically over 12 weeks revealed that the active treatment was associated with significant improvements in treadmill exercise time, cardiothoracic ratio, ejection fraction, functional status and clinical signs and symptoms of heart failure. Lisinopril exhibited a mild first-dose effect on blood pressure that was not significantly different from that observed with placebo. The incidence of adverse experiences was not markedly different in the 2 study groups, with only mild hypotension and dizziness occurring more frequently in association with the active medication.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

Lisinopril versus placebo in older congestive heart failure patients.

This article reports the results of a multicenter international study of the use of lisinopril in patients with congestive heart failure also receiving digoxin, diuretics, or both. Two thirds of the 130 subjects enrolled in the study received lisinopril and one third received placebo. Lisinopril treatment led to a significant improvement in both bicycle and treadmill exercise tolerance, New York Heart Association classification status, cardiac function assessed noninvasively, and symptomatology. There was no age differentiation; the same improvement was achieved in the 35 patients over 65 years old as in the younger patients. There was a mild decrease in both systolic and diastolic blood pressure in patients receiving lisinopril, peaking at seven hours. These changes, however, were not significantly different from those seen with placebo. Apart from one patient in whom hypotension developed followed by reversible renal failure, there were no serious adverse effects, and the incidence of sudden death and biochemical abnormalities was no different from that seen with placebo. This study confirms that this agent is an effective, safe, well-tolerated agent in the treatment of congestive cardiac failure and is equally applicable to younger and older patients.

Age Factors↗
PubMed1987

Transdermal clonidine (Catapres-TTS) monotherapy in the management of mild hypertension in general practice.

The efficacy and patient acceptance of transdermal clonidine applied once a week were assessed in 62 mild hypertensives previously controlled on a diuretic and/or beta-blocker in a general practice setting involving 18 general practitioners. Patients underwent 3-5 week wash-out period and those patients whose mean seated diastolic blood pressure returned to levels between 91-105 mmHg or increased by greater than 10 mmHg above the initial value, were titrated with transdermal clonidine (Catapres-TTS-1, 2, or 3) and maintained on the optimal dose for 3 months with monthly check-ups. Satisfactory response of blood pressure to levels below 90 mmHg or greater than 10 mmHg reduction from the wash-out level was obtained in 85% of patients who completed the titration phase; nine patients failed to achieve a satisfactory blood pressure control. There was no significant difference in blood pressure response between previous therapy and transdermal clonidine treatment. Systemic side effects were minimal. Eight patients withdrew because of local allergic contact dermatitis. This study confirms that transdermal clonidine is at least as effective in reducing blood pressure as diuretic and/or beta-blocker therapy.

Administration, Cutaneous↗
PubMed1987

Contact sensitivity by diisocyanates: potencies and cross-reactivities.

The dermal sensitizing potencies of four diisocyanates were investigated using the mouse ear-swelling test (MEST) with BALB/cBy mice. Mice were administered topical doses of diisocyanates to the abdomen and were challenged on the ear 4 days later with a nonirritating dose of chemical. The increase in ear thickness at 24 hr postchallenge indicated the extent of contact sensitivity. Ear thickness increase plotted against the log of the dose of diisocyanate indicated three regions of effects: a no-effect region, a dose-response region, and a region of reduced response at highest dosages. The potencies of the diisocyanates expressed as the SD50 (dose required to sensitize 50% of the animals in each group) were hexamethylene diisocyanate, 0.088 mg/kg; diphenylmethane-4,4'-diisocyanate, 0.73 mg/kg; and toluene diisocyanate, 5.3 mg/kg. For dicyclohexylmethane diisocyanate, the steep dose-response curve suggested a threshold-type response occurring at 0.24 mg/kg. The specificity of sensitization was evaluated by challenging sensitized animals with heterologous diisocyanates. The homologous reactions were always the most extensive. However, cross-reactions were noted between aryl and alkyl diisocyanates. Toluene diisocyanate, the weakest sensitizer, elicited the fewest cross-reactions. The MEST proved to be a simple and effective method for assessing delayed-type hypersensitivity without need of adjuvants, occlusive patches, abrasions, or other procedures which fail to mimic industrial exposures. The observation that very high exposures resulted in reduced response indicates that protocols which generate dose-response data must be utilized to accurately assess the sensitizing potencies of industrial chemicals.

Animals↗
PubMed1987

Placebo-controlled study of lisinopril in congestive heart failure: a multicentre study.

A double-blind randomised, parallel, placebo-controlled study was performed in patients with congestive heart failure, at 13 centres in 10 countries, to assess the efficacy and safety of lisinopril, a new angiotensin-converting enzyme inhibitor. After a 2-week run-in period, 130 patients receiving digoxin and/or diuretics were randomised to 12 weeks of treatment with lisinopril 5 mg daily (87 patients) or with placebo (43 patients), with an option to increase lisinopril dosage to 10 or 20 mg. Patients treated with lisinopril improved significantly more than placebo-treated patients (p less than 0.05) for all clinical parameters except oedema and paroxysmal nocturnal dyspnoea. Left ventricular ejection fraction rose by 8% in lisinopril patients compared to 2% in the placebo group, while the cardiothoracic ratio and echocardiographic end systolic diameter fell in the lisinopril group (p less than 0.01) but not in the placebo group. Exercise duration was greater in the lisinopril group at all timepoints, and the increase in exercise duration at 12 weeks was greater by more than 2 min in the lisinopril group as compared to the placebo group (p less than 0.01). Changes in clinical and noninvasive parameters such as the New York Heart Association status, were well correlated with changes in exercise duration. Four patients in the lisinopril group and three in the placebo group died in this study, and there were 31 adverse clinical experiences in the 87 lisinopril-treated patients compared to 13 in the 43 placebo-treated patients. We conclude that lisinopril in doses of 2.5-20 mg/day is well tolerated and effective in patients with heart failure who are receiving digitalis and diuretics.

Adolescent↗
PubMed1986

Long-term results with verapamil in essential hypertension and its influence on serum lipids.

Many studies have confirmed that the treatment of mild and moderate hypertension reduces mortality and morbidity from cardiovascular accidents and cardiac and renal failure; more recent studies suggest that there is some beneficial effect on ischemic heart disease. The harmful metabolic effects of some hypotensive agents on serum potassium, magnesium, uric acid, glucose, renin and lipids might reduce the beneficial effect of controlling raised blood pressure. Also, the adverse effects associated with most antihypertensive drugs have decreased quality of life and, possibly, compliance in many patients. In assessing the value of newer antihypertensive agents, other effects of the drugs must be taken into account. The calcium-channel antagonist verapamil produces a dose-dependent reduction in blood pressure with little postural effect. There is little change in heart rate and the major antihypertensive effect results from a decrease in peripheral vascular resistance, with no accompanying increase in cardiac output. In 75 patients followed for more than 1 year, tolerance to verapamil did not appear to develop, nor were there any significant changes in serum electrolytes or creatinine clearance. Fasting serum lipid levels were measured in 15 patients before and after 3 months of treatment with verapamil (80 to 160 mg, 3 times a day); there was no change in cholesterol, triglycerides or high-density lipoproteins. Verapamil is, therefore, an effective hypotensive agent with a rapid onset of action. Tolerance does not develop with prolonged use, nor does it appear to affect electrolytes or serum lipids adversely. Constipation appears to be its only limiting adverse effect.

Blood Pressure↗
PubMed1986

Combined spironolactone and converting-enzyme inhibitor therapy for refractory heart failure.

Three cases are described of severe congestive heart failure which failed to respond to digitalis, high doses of loop diuretics, and converting-enzyme inhibitors. The addition of spironolactone produced a substantial diuresis associated with clinical and radiological improvement in each case. Although a reversible deterioration in renal function was observed, this drug combination represents a therapeutic option in end-stage heart failure.

Adult↗
PubMed1983

Measurement of the ability to control jaw muscle forces in man.

Subjects were asked to track a moving waveform on an oscilloscope screen, with the output of a force transducer placed between the teeth. It was found that, after a learning period, the error depended upon the clenching force, and that, over the force range studied, the greater the effort demanded, the greater the error.

Adult↗
PubMed1981

Percutaneous transluminal angioplasty: successful cure of malignant hypertension.

The technique of percutaneous transluminal angioplasty has been shown to be an alternative to vascular surgery in some cases of renovascular hypertension. A 40-year-old woman presented with malignant hypertension on the basis of fibromuscular hyperplasia involving her dominant right renal artery. The stenosis was successfully dilated and her blood pressure returned to normal.

Adult↗