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Biomedical subjects

P Simon

Publications and source records attributed to P Simon.

At least 289 records · Page 16Linked to original sources
PubMed1991

Childhood lead poisoning: a Rhode Island perspective.

The Rhode Island Department of Health recognizes lead exposure as the State's most important environmental health problem. Historically, the program has relied on secondary prevention strategies consisting primarily of screening, case-finding, limited environmental intervention and medical management. While secondary prevention of lead toxicity identifies existing cases in a preclinical stage, it does not prevent exposure to lead hazards. The sources of lead exposure need to be appropriately identified and abated if exposures and re-exposures are to be prevented. Because of the ubiquity of lead and practical limitations of available resources, a large number of children with elevated blood lead levels will continue to go unscreened and undetected unless more effective screening strategies are implemented. Present reliance on the free erythrocyte protoporphyrin (FEP) test as a primary screening tool is recognized as an insensitive way to identify children with blood lead levels below 40 micrograms %. With growing evidence of toxicity and long term health effects associated with blood lead levels in the range between 10 and 40 micrograms %, blood lead analysis will need to become part of the routine method of screening.

Child↗
PubMed1990

Cytotoxicity assays using cryopreserved target cells pre-labeled with the fluorescent marker europium.

We describe a method for standardizing cytotoxicity assays by the use of cryopreserved, fluorescently labeled target cells. The cells are labeled in batches with the fluorogenic element europium (Eu) and frozen in multiple aliquots. Replicate aliquots can be thawed on different days and used for cytotoxicity assays. Thawed pre-labeled cells from the same batch are killed reproducibly, allowing cytotoxicity assays to be standardized. The target cells need only be thawed, washed, counted for viability and used. The availability of pre-labeled, cryopreserved targets facilitates the assessment of cytotoxic activity of individual donors at different times. The method also simplifies the use of large panels of target cell types. By using this procedure it is not necessary to maintain active cultures of target cells, nor is it necessary to use and dispose of radioisotopes. These pre-labeled target cells can be used in various assays where the result is a destroyed target cell such as cell-mediated cytotoxicity, complement mediated cytotoxicity, or antibody-dependent cellular cytotoxicity.

Cell Survival↗
PubMed1990

Adrenal-dependent leucopenia after short-term exposure to various airborne irritants in rats.

Leucopenia without any change in differential or red blood cell counts was observed in rats exposed for 4 h to increasing concentrations of the following airborne irritants: acetic acid, benzyl chloride, 1,2-dichlorobenzene, ethyl acetate, ethyl acrylate, formaldehyde, isophorone, mesityl oxide, phenol, styrene, toluene diisocyanate and vinyl toluene. This effect was abolished by adrenalectomy. Vinyl toluene and 1,2-dichlorobenzene induced leucopenia at levels as low as their current occupational standards of 50 ppm. With the exception of 1,2-dichlorobenzene, the tested compounds caused leucopenia only when exposure reached the irritant level. It is discussed that stress associated with the irritative effect of chemicals can confound specific haematological effects.

Adrenal Glands↗
PubMed1990

Decrease in the rat bronchial acetylcholinesterase activity after toluene diisocyanate inhalation.

Acetylcholinesterase (AChE) activity was measured in bronchial tissue homogenate and blood from rats subjected to single and repeated 4-h daily inhalation exposure to toluene diisocyanate (TDI) or control atmospheres. A single 4-h exposure to TDI in the concentration range of 0.7-4.3 ppm did not decrease AChE activity in bronchial tissue but a 4-h exposure to 0.6 ppm TDI, or greater, for two consecutive days did reduce this activity (19% to 33% of the controls). Increasing the level of exposure to TDI for two consecutive days from 0.6 to 4.0 ppm and extending the length of exposure to 1.2 ppm TDI from 2 to 4, 9 or 14 days produced no further decrease in bronchial ACHE activity. Throughout these experiments, blood AChE activity remained unchanged. In rats exposed to 0.3 or 1 ppm TDI for 3 weeks, staining of the bronchial smooth muscle for AChE was reduced (36% of the controls) after exposure to 1 ppm TDI. These results support, for the first time, in vivo and localized anti-AChE activity by TDI.

Acetylcholinesterase↗
PubMed1990

Protracted anuria due to active vasoconstriction in primary or secondary malignant hypertension.

Anuria complicated the malignant phase of hypertension in twelve patients (ten males and two females). Five were black; five had primary hypertension; one had HBs virus angiitis; the six remaining cases suffered from previously documented renal disease, including two with Berger's disease. Renal angiography showed interruption of renal blood flow as far as the main branches of the renal artery and/or a false impression of 'cortical necrosis' and of 'renal infarcts'. In contrast, renal biopsy did not show irreversible vascular damage. Thus, anuria was mainly functional and due to active renal vasoconstriction. This was confirmed by the subsequent course; diuresis resumed after 1 week to 24 months of dialysis. Repeat angiography in six cases showed recovery of renal circulation and disappearance of 'cortical infarcts', even when plasma renin activity remained elevated and hypertension was not controlled. In one case captopril induced a new reversible episode of anuria. These observations suggest that active vasoconstriction with prolonged anuria might be due to some vasoconstrictive substance other than angiotensin II.

Adult↗
PubMed1990

Daytime wakefulness following a bedtime oral dose of zolpidem 20 mg, flunitrazepam 2 mg and placebo.

1. The effects of zolpidem 20 mg, flunitrazepam 2 mg and placebo, administered at bed time, were studied in 12 healthy young male volunteers. 2. The assessments included, at awakening, subjective ratings of overnight sleep, cognitive function, psychomotor performance (digit symbol substitution, choice reaction time, flicker fusion threshold), subjective ratings of alertness, and plasma assay of residual drug concentration. Daytime sleep propensity during the day after dosing was evaluated with the multiple sleep latency test. 3. Compared with placebo, both active drugs improved subjective assessment of the ease of getting to sleep. At awakening, under flunitrazepam treatment, the reduction of performance, on memory and psychomotor tests, paralleled an increased subjective rating of sleepiness, but zolpidem treatment left subjects unimpaired compared with placebo. Similarly, daytime sleep propensity was enhanced throughout the following day under flunitrazepam treatment, but not under zolpidem treatment. Plasma assay for residual drug concentration at awakening found significant amounts of flunitrazepam and marginal amounts of zolpidem. 4. Results indicate that zolpidem 20 mg is devoid of residual effects in a range of tasks that were sensitive enough to demonstrate a prolonged wakefulness impairment following flunitrzepam 2 mg in healthy volunteers.

Administration, Oral↗
PubMed1990

Intraoperative echocardiography in cardiac emergencies.

Echocardiography has brought about a new modality of surgical decision making in open heart surgery. Especially in urgent and emergency surgery, echocardiography can provide decisive insight into the underlying pathophysiological processes, improved monitoring of cardiac function, as well as immediate quality control after the procedure. The importance of intraoperative echocardiography for the cardiac surgeon is illustrated in a number of selected case reports.

Aged↗
PubMed1990

Intraoperative echocardiographic assessment of global and regional myocardial function.

Intraoperative echocardiography is gaining increasing importance to the anesthesiologist and the surgeon in the management of high-risk patients undergoing cardiac and major noncardiac surgery. It can provide for the noninvasive, immediate assessment of global left ventricular function, and its determinants; preload, afterload, and myocardial contractility. In addition, abnormalities of regional myocardial function, as a marker of myocardial ischemia, can be easily identified. With the advent of transesophageal echocardiography, this imaging technique can be more widely applied without interfering with the surgical procedure, not only increasing our ability to adequately monitor the patient, but also guiding our therapy and providing additional insights into the physiological and pathophysiological processes affecting the heart during surgery.

Cardiac Surgical Procedures↗
PubMed1990

Echocardiographic assessment of mitral valve function during mechanical cardiopulmonary resuscitation in pigs.

Using two-dimensional and M-mode echocardiography, mitral valve function was assessed during mechanical cardiopulmonary resuscitation (CPR). In 10 anesthetized pigs CPR began 1 min after induction of ventricular fibrillation; in all pigs three different compressive forces (200, 350, and 500 Newton [N]) were applied in randomized sequence for 3 min each, thus resulting in a reduction of anterior-posterior chest diameter by 15%, 20%, and 25%, respectively. Echocardiographic recordings of adequate technical quality were obtained from seven animals. During ventricular fibrillation, mitral valve leaflets showed fibrillatory movements without closure. During CPR systole with a compressive force of 200 N, the mitral valve closed in 114 of 700 CPR cycles (16%). This rate increased significantly (P less than 0.001) to 399 of 584 cycles (68%) with 350 N, and further to 470 of 494 cycles (95%) with 500 N. The higher mitral valve closure incidence was linked to statistically significant increases in systolic cerebral (+125%) and diastolic myocardial perfusion pressures (+136%) and cardiac output. We thus conclude that with low compressive force blood flow during mechanical CPR is due mainly to the chest pump mechanism, whereas the cardiac pump mechanism is effective with high compressive forces.

Animals↗
PubMed1990

[Autosomal dominant polycystic kidney and genetic markers of chromosome 16].

The mutation for autosomal dominant polycystic kidney disease (APKD) has been mapped by linkage analysis on the distal part of the short arm of chromosome 16. We present in this study the results of linkage analysis using the two most tightly linked DNA markers (3'HVR and 24-1) in 183 members of 14 families of a same ethnic origin. We have constructed haplotypes using these two polymorphic probes, and compared the frequency of these on the normal and the affected chromosome. No evidence of linkage heterogeneity was found in our population.

Chromosome Mapping↗
PubMed1990

[The value of perforating cryopreserved massive bone allograft. Histologic data of an allograft removed after 27 months].

The authors reported one documented observation of a deep-frozen, non irradiated, intercalary allograft; it was perforated by drilling and then fixed by a blade plate. This allograft was removed 27 months after its implantation. Histological examination of the removed bone graft showed newly formed mature bone which developed near preexisting devitalized bone. The external cortex was also revitalized and reossified close to the periosteum, as it was previously reported. But osteogenesis filled all the paths of the perforations and extended to the haversian canals located in the vicinity of the perforations. The authors conclude that cortical perforations induce both cortical and medullary osteogenesis of the graft. If osteogenesis is observed in the whole medullary canal, it is more focal and located in the vicinity of the holes in the cortex.

Bone Neoplasms↗
PubMed1990

[Chorionic villi sampling: experience of the initial 500 samples].

We report our experience in first trimester antenatal diagnosis since 1984. Transcervical chorionic villus sampling (CVS) was performed in 498 pregnancies. The rate of abnormal pregnancies was 6%, the rate of chromosomal abnormalities (trisomy) in the indication group "maternal age" was 2%. The fetal loss rate (until 28 weeks) was 3.4% (17 cases), the procedure related loss plus the background loss was 2.4% (12 cases). For 92.8% of the patients a diagnosis was available after 1 CVS procedure. Ultimately an antenatal diagnosis was given to 99% of the women through a second CVS procedure or an amniocentesis or a cordocentesis. No maternal complication was observed.

Chorionic Villi Sampling↗
PubMed1990

[Uncommon surgical treatment of a tibial fibrous bone dysplasia].

The authors present an original method of treatment in prevention of fracture of the tibial shaft applied in one case of polyostosic fibrous dysplasia of bone. They treated this localization by closed intramedullary reaming and stuffage with cancellous bone grafts.

Adolescent↗
PubMed1990

[Efficacy and tolerance of low molecular weight heparin in the prevention of deep venous thrombosis during non-emergent total hip arthroplasty. A prospective, multicenter trial].

A multicenter prospective trial was conducted on 149 patients to test the efficacy and tolerance of low molecular weight heparin (LMWH) in the preventive treatment of deep venous thrombosis consecutive to total hip arthroplastic surgery. An original dose-adjusted protocol was tested, whereby the patients were injected a single dose of LMWH daily, determined on a weight and operation date basis; the prophylactic efficacy of this protocol was assessed by bilateral phlebography performed systematically on the 10th postoperative day. Only 12.9% of patients developed deep venous thrombosis of the lower extremities, and the thrombus formation site was proximal in 3.6% of cases. These rates are low compared with published data and considering the diagnostic criterion used. The low incidence of premature treatment withdrawal and hemorrhagic complication (2%) cases is indicative of the good tolerance of this preventive treatment.

Adult↗
PubMed1990

[Cordocentesis: experience in 391 initial samples].

The first diagnostic cordocentesis was performed in our unit in october 1985. Our 4-year experience is reported: 391 cordocentesis were performed in 360 patients during gestational weeks 14 to 42. The first attempt was successful in 90% of the procedures, 4 samplings failed, there were 4 fetal deaths within one week after diagnostic cordocentesis, one of them appears to be directly linked to the punction. A transient fetal bradycardia was observed in 9.9% of the cases, bleeding occurred in 19% of the cases. The indications for cordocentesis were: risk of fetal infection, karyotyping, hemopathy, search for paternity, assessment of fetal acid-base status, biochemical dosage. Our data confirm that cordocentesis is a safe and reliable diagnostic procedure providing guidelines for management of the pregnancy.

Chromosome Aberrations↗