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Biomedical subjects

R M Jenkins

Publications and source records attributed to R M Jenkins.

17 recordsLinked to original sources
PubMed2000

Diagnostic accuracy of 99mTc-sestamibi breast imaging: multicenter trial results.

UNLABELLED: Although mammography is well established as a first-line tool for breast cancer screening and detection, efforts to develop complementary procedures continue. Observation of 99mTc-sestamibi tumor uptake provided the impetus for its evaluation as an adjunctive technique. This trial's objectives were to determine in a multicenter trial the diagnostic accuracy of 99mTc-sestamibi in women with suspected breast cancer and to investigate factors influencing diagnostic accuracy. METHODS: Our multicenter trial enrolled 673 women (387 with nonpalpable abnormalities; 286 with palpable abnormalities) scheduled for excisional biopsy or mastectomy. Blinded and unblinded interpretations of scintigraphic images were compared with core laboratory established histopathologic diagnoses to define the diagnostic accuracy of 99mTc-sestamibi breast imaging. RESULTS: Blinded readers' diagnostic accuracy was 78%-81%. Inter-reader agreement was excellent, ranging from 95% to 100% (kappa = 0.82-0.99). Overall institutional sensitivity and specificity for 99mTc-sestamibi breast imaging were 75.4% and 82.7%, respectively. In this population with a 40.1% disease prevalence, the positive predictive value was 74.5% and the negative predictive value was 83.4%. The negative predictive value was 94% in patients with a 40% or lower mammographic likelihood of breast cancer. Sensitivity was higher for palpable abnormalities; specificity was higher for nonpalpable abnormalities. Sensitivity was decreased for tumors <1 cm in largest dimension but appeared not to be affected by patient's age. CONCLUSION: As an adjunct to current procedures, 99mTc-sestamibi breast imaging may contribute to patient management decisions in selected populations, including women with dense breasts, mammographically indeterminate lesions >1 cm, and palpable abnormalities.

Biopsy↗
PubMed1995

Weakness in mouse masticatory muscles by repetitive contractions with forced lengthening.

The etiology of myofascial tenderness and pain of masticatory muscles in humans is difficult to understand. Parafunctional oral habits such as tooth grinding or vigorous chewing are thought to be factors. The objective of this study was to determine if masticatory muscles are susceptible to weakness and injury induced by repetitive, dynamic, forced-lengthening contractions. Results would support the hypothesis that contraction-induced injuries could occur in hyperactive masticatory muscles of humans in response to parafunctional oral habits. Mice were anesthetized and randomly assigned to three groups: non-treated controls, treated by repetitive passive jaw opening, or treated by repetitive isometric tetanic contractions with lengthening by jaw opening. In each treatment group, masticatory muscle injury was evaluated by contractile tension, plasma creatine kinase, and muscle glycogen. Contractile tension was determined at different stimulation frequencies and was significantly decreased 5 min, 4 h, and 72 h after repetitive contraction/lengthening. Plasma creatine kinase was significantly elevated at 4 but not at 72 h post-treatment in mice subjected to repetitive contraction/lengthening. Masticatory muscle glycogen was not significantly different in any groups at 4 or 72 h post-treatment. These results indicate that contraction injuries can be induced in masticatory muscle of mice by forced lengthening contractions which simulate eccentric contractions.

Analysis of Variance↗
PubMed1994

Effect of the acyl-CoA:cholesterol acyltransferase inhibitor DuP 128 on cholesterol absorption and serum cholesterol in humans.

Intestinal cholesterol esterification by the enzyme acyl-CoA:cholesterol acyltransferase (ACAT) is a presumed prerequisite for cholesterol absorption. We evaluated the effect of a potent, poorly absorbed ACAT inhibitor (DuP 128: N'-(2,4-difluorophenyl)-N-[5-(4,5-diphenyl-1H-imidazol-2-ylthio)pe ntyl]- N-heptylurea) on cholesterol absorption in a randomized trial. Thirty subjects received DuP 128 for 7 weeks, 10 each at 900 mg per day, 1800 mg per day, and 3600 mg per day; six subjects received placebo; and nine subjects received 1 gm neomycin twice a day. Cholesterol absorption determinations used a continuous dual isotope 14C-cholesterol and 3H-beta sitosterol method. DuP 128 (pooled doses) induced at 14.4% +/- 11.4% reduction in cholesterol absorption (p < 0.05 versus placebo): 17.6% +/- 8.4% at 900 mg, 9.1% +/- 11.4% at 1800 mg, and 17.1% +/- 12.9% at 3600 mg. Neomycin induced a 26.4% +/- 10.7% reduction (p < 0.01). After 6 weeks, neomycin reduced serum total and low-density lipoprotein cholesterol by 22.4% +/- 9.2% and 24.0% +/- 11.6%, respectively (p < 0.01 versus placebo). DuP 128 induced reductions of 3.9% +/- 11% (difference not significant) and 4.95% +/- 14.3% (p = 0.05). ACAT inhibitors limit cholesterol absorption in humans; however, the magnitude of the effect, as exemplified by DuP 128, is small.

Adult↗
PubMed1993

Quality of general practitioner referrals to outpatient departments: assessment by specialists and a general practitioner.

Thirty eight specialists in one district health authority were asked to take part in a questionnaire survey to assess the appropriateness of referral and the quality of the referral letter for 20 consecutive new patients each. A total of 705 new patient referrals to 13 specialties were included in the study. Twelve of the 38 specialists were randomly selected and their 234 new patient referral letters were independently assessed by a general practitioner for the appropriateness of the referral decision. The study revealed errors and omissions in between 5% and 28% of referral letters according to the category of information. Thirteen per cent of the new patient referrals were assessed by specialists to be inappropriate and 4% of patients had been referred to an inappropriate specialty. Significantly more of the referrals to medical specialties were inappropriate (20%) than to surgical specialties (9%) (P < 0.01). There were more than three times the number of errors and omissions in the referral letters of referrals assessed as inappropriate than in the referral letters of referrals assessed as appropriate (P < 0.01). The referral letters of referrals assessed as inappropriate were more than nine times as likely to omit the reasons for or objectives of the referral compared with letters for those referrals assessed as appropriate (P < 0.01). There was a good overall agreement between the specialists and general practitioner in their assessment of the appropriateness of the clinical referrals (kappa = 0.614, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Ambulatory Care↗
PubMed1982

The symptomatic and objective effects of nifedipine in combination with beta-blocker therapy in severe angina pectoris.

Nine patients with severe coronary artery disease and disabling angina receiving either regular metoprolol or oxprenolol, together with glyceryl trinitrate tablets as required for chest pain, were studied. Nifedipine 10 mg three times per day was compared to placebo in a double blind randomized control trial, using patient diary cards and exercise tests. The number of recorded episodes of angina during the placebo period of 15.0 +/- 2.1 (mean +/- s.e.m.) per patient per week was significantly reduced to 11.2 +/- 2.5 during the nifedipine period (P less than 0.05). Similarly, the recorded number of glyceryl trinitrate tablets consumed during the placebo period of 12.6 +/- 2.1 was significantly reduced to 9.1 +/- 2.0 tablets per patient per week during the nifedipine period (P less than 0.05). There was a statistically significant increase in both the duration of exercise to onset of chest pain (from 241 +/- 16.3 seconds on placebo to 306 +/- 38.4 seconds on nifedipine (P less than 0.05)) and the total work performed to the onset of chest pain during the nifedipine period compared to the control and placebo periods (P less than 0.05). There was a significant increase (P less than 0.05) in exercise time before the onset of appreciable ST depression (greater than 1 mm) on exercise testing during the nifedipine period (66.2 +/- 4.2 sec) compared to the control period (51.2 +/- 3.0 sec) and placebo periods (58.7 +/- 3.5 sec). Although nifedipine was generally well tolerated, one patient experienced a severe episode of angina whilst taking the drug, which required admission to hospital.

Adult↗
PubMed1981

Variation in response to cytotoxicity of cigarette smoke.

The cytotoxic effect of cigarette smoke condensate on human polymorphs was investigated in vitro by the method of vital dye exclusion. Exposure to 1/800 of the smoke from one high-tar cigarette killed a detectable proportion of a population of 10(6) cells. The response among the cells from 40 healthy people varied widely, the percentage of dead cells ranging from 3% to 66% and from 17% to 87% at exposure levels of 125 micrograms and 250 micrograms cigarette smoke condensate respectively. Differences in individuals' responses were reproducible and unrelated to age or sex or smoking habit. The cells from 10 patients with irreversible obstructive airways disease and probable emphysema were significantly more sensitive than those from 10 patients with no respiratory disability matched for age and smoking habits. Genetically influenced variation in cellular response to cytotoxicity may be an important determinant of the risk of developing emphysema among smokers.

Adult↗
PubMed1981

Alcohol-induced Cushingoid syndrome.

Although it has been known for some time that alcohol affects the hypothalamic-pituitary-adrenal axis, the clinical significance of this disturbance has only recently become recognised. Over the last 5 years, 27 cases of an apparent Cushing's syndrome have been documented, usually resolving within weeks of alcohol withdrawal. Differentiation from the true Cushing's syndrome can be difficult before resolution, which may be prolonged for several months, but an insulin stress test can be useful in their distinction. The syndrome is invariably pituitary dependent but may not be a specific drug effect of ethanol but rather a consequence of the chronic stress of alcoholism.

Adrenocorticotropic Hormone↗
PubMed1979

The ocular hypertensive response following experimental acid burns in the rabbit eye.

Following application of 50 microliter of 2N hydrochloric acid to the rabbit cornea, the intraocular pressure rapidly increases and remains markedly elevated for up to 3 hr. The initial rapid increase in intraocular pressure appears to be the result of acid-induced shrinkage of the outer collagenous coats of the eye. The sustained rise in intraocular pressure is mediated in part by prostaglandin release. Increased prostaglandin-like activity, determined in the aqueous after an acid burn, was greatly inhibited by pretreatment of rabbits with indomethacin and to a much lesser extent by pretreatment with imidazole. Both indomethacin and imidazole essentially abolished the sustained elevation of intraocular pressure after an acid burn. Analysis of changes in pH and protein level in the aqueous implies that the stimulus for prostaglanding release within the eye is the penetration of hydrogen ions into the aqueous humor, with resultant intraocular trauma.

Animals↗
PubMed1979

Pulmonary function in Bechçet's syndrome.

Pulmonary function in Behçet's syndrome has not received much attention, although sporadic cases of airways obstruction have been described. In this series of five cases one had abnormal results with reversible airways obstruction and emphysema. These findings were likely to have been associated with asthma, previous smoking habits and pulmonary tuberculosis, and not another manifestation of Behçet's syndrome.

Adult↗
PubMed1975

An electrogenic component of the potential difference in the rabbit lens.

The normal resting potential of the rabbit lens, -70mV, is altered to -59mV by ouabain concentrations up to 5-1- minus 6M, and to -52mV at 4 degrees C. Ouabain acts only at the anterior lens surface. The temperature effect id completely reversible. The Hodgkin-Katz-Goldman equation can be used with the measured lens potentials and Na+ and K+ levels in the lens and bathing medium to obtain alpha, the ration of the membrane permeabilities to Na+ and K+. The alpha-values obtained were 0.052 at 4 degrees C and 0.053 in 5-10 minus 6M ouabain. These data suggest that the change in potential due to cold and ouabain is caused by an inhibition of an electrogenic Na+ ump in the anterior lens epithelium.

Animals↗