PubMed Health⌕ Search

Biomedical subjects

F Paycha

Publications and source records attributed to F Paycha.

36 records · Page 2Linked to original sources
PubMed1995

[An expert system for the diagnosis of intraocular pressure disorders].

PURPOSE: This expert system (ES) is designed to avoid the four types of diagnosis errors: by omission or by confusion both of which may occur when collecting signs and symptoms and when analyzed data. This ES uses a thesaurus containing 42 classical and objective signs and a comprehensive library. For a given case report, it provides the practitioner with a positive diagnosis, and if possible, one or several etiologies taking into account all the data known about intraocular disorders. METHODS: This ES is run on a PC-compatible computer with 640 KB RAM and without hard drive. The 90 KB program is written in compiled Basic. After checking the case record to rule out nonsenses, the logic considers every sign of the case record as equivalent. Likewise, in the first stage all syndromes are considered of equal likelihood. The syndromic diagnosis is set by identification. Comparisons of prevalence interfere, when needed, in a second phase, within the framework of etiological diagnosis. RESULTS: When tested on a set of 180 cases records combined with 115 cases extracted from the literature corresponding to more than 1,900 diaagnoses, this ES yielded 100% correct positive and differential diagnoses, thus validating the logial hypotheses. Probability of error by omission was less than a 3% and probability of error by confusion was well below 0.1%. Besides, the logical analysis shelds light on the intellectual mechanisms of diagnosis. CONCLUSIONS: This ES is user-friendly, easy to update and can answer clinical problems the ophthalmologist has to cope with in diagnosis and therapy of intraocular pressure disorders.

Acute Disease↗
PubMed1992

Non-invasive identification of severe coronary artery disease in patients with long-standing diabetes mellitus.

OBJECTIVES: To detect severe coronary artery disease in asymptomatic middle-aged diabetic patients exposed to coronary artery disease risk factors. PATIENTS AND METHODS: Forty-four middle-aged patients (30 to 65 years of age) with a known duration of diabetes exceeding 10 years and at least one additional cardiovascular risk factor were studied. Patients were free of anginal chest pain and had a normal 12-lead ECG at rest. All patients underwent 24-hour ambulatory ECG, maximal bicycle exercise electrocardiography and intravenous dipyridamole thallium myocardial scintigraphy. If one of these 3 non-invasive tests revealed signs of myocardial ischaemia, a coronary angiography was performed. RESULTS: Non-invasive investigation yielded the diagnosis of myocardial ischaemia in 9/44 patients (20%). Six of the 9 patients had significant coronary artery stenoses (> 70% narrowing) and 5 exhibited severe triple-vessel disease. With dipyridamole thallium scintigraphy, the positive predictive value for diagnosis of coronary artery disease was optimal. CONCLUSION: In diabetic patients with additional coronary risk factors, periodical thorough clinical examination and resting ECG may fail to detect severe coronary disease. More sophisticated cardiovascular non-invasive tests should then be proposed as part of the periodical care of these patients.

Coronary Angiography↗
PubMed1992

[Negativity of the exercise thallium test despite tight stenosis of the common trunk of the left coronary artery].

The authors report a case of severe angina linked to subocclusive ostial stenosis of the common trunk of the left coronary, characterised by the contrast between a very positive stress test on the basis of clinical and electrocardiographic parameters and a negative Thallium stress test. The occasion is taken to review the sensitivity of Thallium stress testing in lesions of the common trunk.

Constriction, Pathologic↗
PubMed1989

Prevalence and significance of left ventricular filling abnormalities determined by Doppler echocardiography in young type I (insulin-dependent) diabetic patients.

In 16 insulin-dependent diabetic patients, 36 +/- 8 years old with no microangiopathy, hypertension or coronary artery disease, and 16 healthy control subjects matched for sex, age and body surface area, the following parameters were obtained by Doppler-echocardiography: (1) end-diastolic left ventricular thickness and radius; (2) aortic pulse wave velocity; (3) mitral flow with measurement of early and late (atrial) peak velocities (E and A), pressure half-time and the velocity time integrals of the entire mitral curve and of the atrial wave; and (4) isovolumic relaxation time (i.e., the time between aortic closure and the mitral opening signals recorded simultaneously by continuous-wave Doppler). Heart rate and systolic blood pressure were not different in the 2 groups. Aortic pulse wave velocity and the wall thickness to radius ratio were significantly increased in the diabetic patients compared to the controls. E was significantly reduced whereas A/E, pressure half-time, the atrial contribution to the left ventricular filling (i.e., the ratio of the atrial velocity time integral to the mitral velocity time integral) and the isovolumic relaxation time were significantly increased in the diabetic group versus the control subjects. Lastly, 11 of 16 diabetic patients (69%) had at least 2 of the following abnormalities: A/E greater than 0.71, an atrial contribution to the left ventricular filling greater than 0.25, a pressure half-time greater than 50 ms and an isovolumic relaxation time greater than 88 ms. No correlations were found between the wall thickness to radius ratio, aortic pulse wave velocity and the filling indexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Solitary increased tibial uptake of 99mTc-diphosphonate unmasking pancreatic tumor-related medullary fat necrosis.

Pancreatic inflammation and tumors can induce various systemic lesions of steatonecrosis. We report here the case of a 73-year-old woman presenting a painful left leg. Roentgenograms and tomograms of the left tibia were normal. Radionuclide bone scan showed diffuse increased uptake in the whole tibia and a CT scan of the same region demonstrated an unusual pattern of bone tumor. Tibial biopsy revealed intra medullary steatonecrosis and led to the discovery of a pancreatic carcinoma.

Adenocarcinoma↗
PubMed1989

Measurement and clinical and pharmacokinetic implications of diffusion coefficients of antibiotics in tissues.

A method for determining diffusion coefficients of four antibiotics in extracellular tissue space according to Fick's law is described. This new method was applied to rat brain tissue and to agar. After diffusion of the antibiotic in one axis, the gradient concentration was determined with microvoltammetric electrodes. These microelectrodes (1 micron at the extreme tip) measured the free diffusible form of electroactive antibiotics in the extracellular brain space. Metronidazole, chloramphenicol succinate, cefsulodin, and piperacillin gave diffusion coefficients ranging from 0.1 x 10(-6) to 0.2 x 10(-6) cm2 . s-1 in tissue; chloramphenicol base, which is positively charged, gave a coefficient of 0.04 x 10(-6) cm2 . s-1. The coefficient ranged from 0.6 x 10(-6) to 1.2 x 10(-6) cm2 . s-1 in agar. These coefficients were used to simulate antibiotic concentrations in infectious sites and between capillaries by using a simple model of plane diffusion.

Animals↗
PubMed1989

[Preoperative localization of parathyroid adenoma with technetium and thallium double-labeling scintigraphy. Difficulties related to associated thyroid lesions].

Technetium and thallium double-labeling scintigraphy with image subtraction was carried out on 63 patients suspected of having primary hyperparathyroidism, with or without thyroid involvement. Forty-four patients had a normal thyroid image with technetium. The positive foci located by double-labeling in patients who were to undergo surgery always coincided with parathyroid adenoma. In the 16 cases where the initial diagnosis of hyperparathyroidism was not substantiated, the double-labeling test was normal. Thus for these 44 patients, scintigraphy sensitivity was 75% and specificity was 100%. Nineteen patients had an abnormal thyroid image with technetium. In 7 cases, image subtraction following double-labeling yielded uninterpretable data. In 12 other patients, the positive foci located outside the thyroid by double-labeling coincided with a parathyroid adenoma, whereas this was true for only one patient whose positive foci were located inside the thyroid; a parathyroid adenoma was not detected preoperatively in 4 patients. This double-labeling test is thus useful in locating parathyroid adenomas when technetium scintigraphy of the thyroid is normal; when it is abnormal, double-labeling is advantageous only in cases of extra-thyroid foci.

Adenoma↗
PubMed1988

Reversibility by dipyridamole of thallium-201 myocardial scan defects in patients with sarcoidosis.

PURPOSE: In order to clarify the significance of anginal pain and myocardial thallium-201 scan defects in cardiac sarcoidosis, the pharmacologic effect of dipyridamole on myocardial perfusion was assessed by planar thallium-201 myocardial scintigraphy in patients with sarcoidosis. PATIENTS AND METHODS: Thallium-201 myocardial scintigraphy was performed at rest and after 0.56 mg/kg intravenous dipyridamole during four minutes in 16 patients with sarcoidosis. The myocardial scan (45-degree and 70-degree left anterior oblique, and anterior views) was divided into 15 segments. Results were evaluated by the number of segmental defects and with a global perfusion score (from 0 to 60) by a semi-quantitative index depending on the size and severity of myocardial thallium-201 defects. RESULTS: Thirteen of the 16 patients showed partial or total reversion of their thallium-201 defects on redistribution scanning either at rest or after dipyridamole. The mean (+/- SD) number of myocardial perfusion defects that were present in all the patients decreased from 5.31 +/- 1.78 at rest to 3.25 +/- 2.52 after redistribution (p less than 0.001) and to 2.19 +/- 2.10 after dipyridamole (p less than 0.001). The mean global perfusion score increased from 53.2 +/- 3.0 at rest to 56.2 +/- 2.9 after redistribution (p less than 0.001) and to 57.2 +/- 2.7 after dipyridamole (p less than 0.001). A significant correlation (r = 0.82, p less than 0.001) was found between the increase of global perfusion score on redistribution and after dipyridamole. CONCLUSION: The reversibility of myocardial scan defects is a common finding in sarcoidosis. It makes unlikely the role of scar fibrosis or extensive confluent granulomas as a mechanism for such defects. The effect of dipyridamole suggests the presence of reversible disorders lying at the coronary microvascular level.

Adult↗
PubMed1986

[The assisted-diagnosis by identification program, an expert system for acquired ocular hypertension in adults].

Computer Aided Diagnosis by Identification packages are expert systems which proceed by iterative comparisons sign by sign between patient's cases and data encased in their clinical memory. They draw straight forward inference from thought processes analyses that lead to diagnosis: comparison between patient's own case report and acquired identified situation, error factors: ignorance or non-performance and, lastly rules to subscribe to: perfect knowledge of every kind of glaucoma and for every kind, perfect knowledge of every sign. Formalization of the problem specifies the algorithm, the miscellaneous solutions: single hypothesis and multiple hypothesis, and their respective values. In order to build up the clinical library, literature search is required to be comprehensive: treaty, reviews, papers, communications and personal case-reports. Outputs are retrieved in an average time-lag of 15 seconds, and are expressed as a list from which only the physician can make out the meaning.

Adult↗
PubMed1985

Paradoxical technetium-thallium subtraction scan in a case of parathyroid adenoma.

A technetium-thallium (99mTcO4-201Tl) subtraction scan was performed in a patient with clinical and biological evidence of hyperparathyroidism. The 201Tl image indicated a normal thyroid gland. The 99mTcO4 image revealed a left inferior thyroidal extension with an intense and transient focus corresponding to an ultrasonographic nodule. The transient character of the focus was not explicable in terms of vascular kinetics. A supplementary scintigram using 123I confirmed the presence of an inferior extension of the thyroid, but no increased uptake was found. A nodule weighing 250 mg containing a parathyroid adenoma surrounded by normal thyroidal tissue was excised at the focus site. Biological serum levels returned to normal after the operation. It is concluded that the analysis of 99mTcO4 dynamic data could improve the accuracy of parathyroid subtraction scintigraphy.

Adenoma↗