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Biomedical subjects

P Simon

Publications and source records attributed to P Simon.

At least 199 records · Page 11Linked to original sources
PubMed1995

The Breuer-Hering reflex in humans. Effects of pulmonary denervation and hypocapnia.

Passive lung inflation in humans causes reflex expiratory prolongation that is abolished by vagal blockade. We have studied two aspects of this classic Breuer-Hering reflex in humans: the effect of pulmonary denervation from bilateral lung transplantation, and the effect of alveolar hypocapnia. Lung inflations were performed in six normal subjects and four lung transplant patients during triazolam-induced sleep using a negative pressure body box. Lung inflation with isocapnic gas in normal subjects resulted in expiratory prolongation lasting up to 60 s and occurring at a volume threshold of 40 to 60% of inspiratory capacity (1.1 to 1.7 L). Expiratory prolongation increased in a graded fashion as volume of lung inflation increased. Inhibition of inspiration at any given inflation volume was prolonged by inflations with air as compared with inflations with isocapnic gas. In lung transplant patients lung inflations of up to 2 L caused no prolongation of expiration. We conclude that bilateral lung transplantation abolished expression of the reflex in humans, and that in normal intact humans the duration of expiratory prolongation with lung inflation is prolonged by alveolar hypocapnia.

Adult↗
PubMed1995

Surgical treatment of type A aortic dissections. Results with profound hypothermia and circulatory arrest.

Type A aortic dissection still presents an emergency situation in cardiac surgery that is associated with high morbidity and mortality rates. There has been a significant improvement in the surgical outcome since the introduction of deep hypothermia and circulatory arrest. In this study, we discuss our results after operative repair of ascending aortic dissections, using deep hypothermia and circulatory arrest. This study presents the results of 67 patients (43 men, 24 women) from 18 through 81 years of age (mean, 54 years) who underwent surgery for type A dissecting aneurysm over a period of 4 years. Type A dissection (52 acute and 15 chronic cases) was due to Marfan syndrome in 12 patients, to atherosclerotic disease of the aorta in 27 patients, and to traumatic injury in 1 patient. Hypertension as the only pathologic finding was observed in 27 patients. Deep hypothermia (confirmed by isoelectric electroencephalogram) and circulatory arrest were induced in all patients. Two patients died intraoperatively due to massive bleeding (intraoperative mortality, 3%). The 30-day mortality rate was 30% (n = 20). Causes of perioperative deaths in order of frequency were multi-organ failure (n = 11), myocardial infarction (n = 2), postoperative bleeding (n = 2), cerebrovascular insult (n = 2), and sepsis (n = 1). The mean intensive care unit stay of the surviving 47 patients (72%) was 8 days, followed by a mean of 21 additional days in the hospital. Our experience with profound hypothermia and circulatory arrest, used in combination with coated grafts, supports our conviction that this is the method of choice for the treatment of type A dissecting aneurysm.

Adolescent↗
PubMed1995

[Surgery of thoracic and thoraco-abdominal aneurysms using deep hypothermia and cardiovascular arrest with continuous administration of blood cardioplegia].

Between January 1991 and February 1993, 14 patients (3 female, 11 male) aged between 21 and 79 years (mean 50 years) underwent reconstruction of the thoracic (n = 7) and thoracoabdominal aorta (n = 7). Four patients had previously undergone operation of the ascending aorta, in 3 patients coronary artery by pass grafting was performed before. All patients were operated using cardiopulmonary bypass with continuous blood cardioplegia, hypothermic circulatory arrest (11 degrees C nasopharyngeal temperature, 0-EEG) and posterolateral exposure. All patent lower intercostal and lumbar arteries (Th3-L5) were reimplanted. The 30-day mortality after repair of the thoracic aorta was 0, after replacement of the thoracoabdominal aorta 28.5% (n = 2). One patient died 70 days after replacement of the thoracic aorta as a consequence of a perioperative stroke. None of the surviving 11 patients developed a permanent neurologic deficit, renal or cardiac dysfunction. The average intensive care stay was 6 days for patients after replacement of the thoracic and 18 days for patients after replacement of the thoracoabdominal aorta. Our results indicate the method of elective hypothermia and circulatory arrest effective in spinal cord protection. The increase in the tolerable duration of spinal cord ischemia supports the reimplantation of all intercostal and lumbar vessels.

Adult↗
PubMed1995

Aortic valve resuspension in ascending aortic aneurysm repair with aortic insufficiency.

BACKGROUND: The known complications of prosthetic valve replacement in patients with an ascending aortic aneurysm and secondary aortic regurgitation who frequently have a morphologically normal aortic valve have prompted interest in valve-sparing aneurysm repair procedures. The aim of this study was to define the echocardiographic criteria for identifying suitable candidates for ascending aortic aneurysm repair that spares the aortic valve. We also examined the perioperative and intermediate-term results of this innovative procedure. METHODS: Fifteen patients underwent ascending aortic replacement with resuspension of the native valve within a vascular prosthesis and reimplantation of the coronary ostia. Echocardiography was performed preoperatively and intraoperatively, before discharge, and during follow-up. Thirteen patients had nondissecting aneurysms, and 2 patients had a Standford type A aortic dissection. The mean age of the patients was 48 +/- 18 years. Only patients with morphologically normal aortic leaflets and leaflets of similar size were selected. RESULTS: There was one death perioperatively, and this was due to sepsis. The procedure failed in 1 patient, and a valved conduit was implanted during the same operation. In the 13 others the aortic annulus diameter was significantly reduced from 27.1 +/- 2.2 mm preoperatively to 22.2 +/- 1.9 mm postoperatively (p < 0.05). The severity of aortic insufficiency decreased from 2.9 +/- 0.7 to 0.6 +/- 0.4 (p < 0.05). The peak aortic gradient increased from 11.5 +/- 6.5 to 20.3 +/- 16 mm Hg. A slight increase in the aortic annulus diameter to 24.3 +/- 1.0 mm and normalization of the peak aortic gradient to 9.8 +/- 7.8 mm Hg were noted at follow-up. There was no significant increase in aortic insufficiency. CONCLUSIONS: In selected patients undergoing ascending aortic aneurysm repair who have normal aortic leaflets but secondary aortic regurgitation, the native valve can be spared through this novel operation. The aortic annulus size is reduced significantly, thereby effectively eliminating hemodynamically significant aortic regurgitation. The intermediate-term results are promising, but the long-term durability of this type of repair needs to be determined.

Adult↗
PubMed1995

[Fat embolism still exists. A retrospective study of 17 cases in a surgical intensive care unit].

Fat embolism is a severe complication in patients with femoral fractures. This retrospective study records 17 cases of post traumatic fat embolism diagnosed between 1979 and 1993 among 430 patients admitted for femoral fractures (incidence: 2.7%). These cases underline the high frequency of early hypovolaemia (10/17), of respiratory and cerebral disorders (15/17), all occurring during the first post trauma week. Three cases were observed in the postoperative period. Severity of fat embolism is proved by three deaths and a mean mechanical ventilation period of 13 days. With early osteosynthesis, incidence of fat embolism could be lowered to 0.2%. Prevention is based on osteosynthesis, avoidance of hypovolemia and of hypoalbuminemia.

Critical Care↗
PubMed1995

[Development of extrarenal complications of chronic renal insufficiency in patients treated by peritoneal dialysis].

As other Renal Replacement therapies, peritoneal dialysis has to control the morbid events due to severe uremia and to prevent new pathology due to long term dialysis. This review concerns major studies published in literature during the last ten years. Critical analysis has permitted to define the benefits and the disadvantages of this treatment method. When a patient has a residual diuresis, peritoneal dialysis is efficient: 1) to control cardio-vascular events due to chronic renal failure, 2) to remove beta 2-microglobulin, 3) to improve anemia due to uremia without using recombinant human erythropoietin, 4) to reduce the risk of developing aplasic bone by using a dialysate calcium concentration of 2.5 mEq/liter and to control secondary hyperparathyroidism by using calcitriol.

Anemia↗
PubMed1995

[Epidemiology of primary glomerulopathies in a French region. Variations as a function of age in patients].

Between January 1st, 1976 and December 31st, 1990, histological diagnosis of primary glomerular diseases (PGD) was made in 480 patients born and living at the time of diagnosis in a region of France comprising 410,664 inhabitants, of whom 390,574 were aged from 10 to 80 years. The prevalence of PGD during a 70-year exposure to risk (10-80 years of age) was evaluated to 5.7 in 1000 (7.6 in 1000 males and 3,8 in 1000 females). The most common PGD was IgA nephropathy with a prevalence of 1.9 in 1000 (3.3 in 1000 males, 1 in 1000 females). The annual incidence of the disease was evaluated separately for 3 consecutive 5-year periods: period A (1976-80), period B (1981-85), and period C (1986-90). Within each of these 3 periods the number of patients with PGD was 179, 170 and 131 respectively, and annual incidence was 9.3, 8.8 and 6.7 in 100,000. The incidence of IgA nephropathy remained the same throughout the 3 periods: 2.6, 3.1 and 2.5 in 100,000. The incidence of membranoproliferative glomerulonephritis decreased from 1981 onward (0.9, 0.5 and 0.15/100,000). Acute streptococcal glomerulonephritis virtually disappeared during periods B and C. Lipoid nephrosis was less frequent in period C and idiopathic proliferative glomerulonephritis with crescents slightly increased (0.3, 0.3 and 0.6 in 100,000). There was no significant difference between the 3 periods regarding the incidence of other PGD. Incidence of IgA nephropathy was 3 to 4-fold higher in the adult aged from 20 to 60 years than in the elderly. In contrast, membranous nephropathy was 3 fold more frequent in the elderly than in the adult. Therefore only some histopathological forms have a different incidence according to age, but the major information furnished by this study is that the risk of occurrence of a PGD is similar in the population living in the area, whatever the age group (10-19 years: 6.4/10(5) inhabitants, 20-39: 7.1/10(5), 40-59: 8.4/10(5), 60-79: 8.4/10(5)). Finally, we confirm that the most common PGD going to end stage renal disease was IgA nephropathy, particularly under 60 years of age (0.8/10(5)). In contrast, membranous nephropathy was a less frequent cause of ESRD (0.2/10(5)).

Adolescent↗
PubMed1995

[Results of valve-sparing correction of aortic valve insufficiency].

The risk of valve-related complications and the necessity of anticoagulation in patients with prosthetic valves, has led to new operative techniques in the correction of severe aortic insufficiency. In the last 2 years, 35 patients (mean age 41.3 years, range 10-80 years) with aortic insufficiency underwent reconstructive valves surgery. Eighteen patients had a commissuroplasty with or without triangular resection. In 5 patients with perforation, the valves could be reconstructed with a pericardial patch. In 12 patients with insufficiency due to aortic aneurysm, the valves were resuspended within the aortic prosthesis. In 2 patients the aortic valves were replaced intraoperatively because of unsatisfactory results. The perioperative mortality was 5.7%. The echocardiographic degree of aortic insufficiency decreased from 3.3 +/- 0.5 preoperatively to 0.45 +/- 0.53 postoperatively. Two patients were reoperated within the first week. Five of 23 patients at 1-year follow-up have mild to moderate aortic insufficiency. Mean ventricular dimensions and function at discharge and after 1-year follow-up are normal. With the new operative techniques described recently, valve-sparing corrections of aortic insufficiency are possible in an increasing number of patients, and autologous valve tissue can be saved. With more refinement of surgical technique, early postoperative results will further improve.

Adolescent↗
PubMed1995

Nafadotride, a potent preferential dopamine D3 receptor antagonist, activates locomotion in rodents.

Nafadotride (N[(n-butyl-2-pyrrolidinyl)methyl]-1-methoxy-4-cyano naphtalene-2-carboxamide) is a novel compound, which inhibits potently and stereoselectively [125I]iodosulpride binding at recombinant human dopamine D3 receptors. the levoisomer displays an apparent Ki value of 0.3 nM at the dopamine D3 receptor, but is 10 times less potent at the human recombinant dopamine D2 receptor. In comparison, the dextroisomer displays 20-fold less apparent affinity at the dopamine D3 receptor and reduced (2-fold) selectivity. l-Nafadotride displays iow, micromolar affinity at dopamine D1 and D4 receptors and negligible apparent affinity at various other receptors. In dopamine D3 receptor-transfected NG-108 15 cells, in which dopamine agonists increase mitogenesis, l-nafadotride has no intrinsic activity, but competitively antagonizes the quinpirole-induced mitogenetic response, monitored by [3H]thymidine incorporation with a pA2 of 9.6. In dopamine D2 receptor-transfected Chinese Hamster Ovary cells, l-nafadotride also behaves as a competitive antagonist of quinpirole-induced mitogenesis with an 11-fold lower potency. These studies establish nafadotride as a pure, extremely potent, competitive and preferential dopamine D3 receptor antagonist in vitro. l-Nafadotride displaces in vivo N-[3H]propylnorapomorphine accumulation at lower dosage and for longer periods in limbic structures, containing both dopamine D2 and D3 receptors than in the stratum, containing dopamine D2 receptor only. At low dosage (0.1-1 mg/kg), nafadotride, unlike haloperidol, a dopamine D2 receptor-preferring antagonist, increases spontaneous locomotion of habituated rats and climbing behavior of mice, at doses that do not modify striatal homovanillic acid levels. At high dosage (1-100 mg/kg), nafadotride, like haloperidol, produces catalepsy and antagonizes apomorphine-induced climbing.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Relationship between serum beta 2-microglobulin, bone histology, and dialysis membranes in uraemic patients.

BACKGROUND: beta 2-Microglobulin (beta 2M) is the main constituent of osteoarticular amyloid deposits in haemodialysis patients. When dialysed with cellulosic (C) membrane such patients present a higher incidence of beta 2M-related amyloid arthropathy than with synthetic high-flux (SHF) membrane, and they have higher serum levels of beta 2M. This could favour beta 2M deposition as amyloid fibrils and/or modify bone and cartilage metabolism. METHODS: We examined 56 uraemic patients dialysed in the same centre for 7.5 +/- 4.8 years (mean +/- SD). Based on bone histomorphometry criteria they were classified into either high-turnover bone disease (HTBD, 45 patients) or normal/low-turnover bone disease (N/LTBD, 11 patients). A subgroup of 30 patients had been dialysed with the same dialysis membrane for at least 18 months prior to study, 8 on C and 22 on SHF membrane. RESULTS: Serum intact parathyroid hormone levels were not different between the two patient subgroups. In contrast, serum beta 2M levels were higher in patients on C than on SHF membrane: 59.8 +/- 14.1 versus 32.8 +/- 8.7 mg/l, and so were serum total alkaline phosphatase and osteocalcin levels: 323 +/- 167 versus 173 +/- 50 IU/l, and 656 +/- 395 versus 288 +/- 263 ng/ml respectively. The increase of these serum markers of bone formation was associated with a higher bone cell number: osteoblast surface, 21.7 +/- 5.1 versus 9.8 +/- 11%; osteoclast surface, 4.27 +/- 1.86 versus 1.96 +/- 1.34%; and osteoclast number/mm2, 2.85 +/- 1.26 versus 1.27 +/- 0.88 respectively. Serum beta 2M was positively correlated with serum osteocalcin (r = 0.58, P < 0.001), bone-specific alkaline phosphatase (bAP) (r = 0.46, P < 0.008), and free pyridinoline (PYD) (r = 0.62, P < 0.002), and negatively correlated, only for HTBD, with osteoid volume: r = -0.40, P < 0.006. Serum beta 2M was higher in patients with HTBD than N/LTBD: CONCLUSION: The bone metabolism of chronic haemodialysis patients may be influenced by dialysis membrane biocompatibility. Moreover, the association of high serum beta 2M with increased bone cell number and serum markers of bone turnover suggests that beta 2M is either another marker of bone cell activity or an activator of bone cells.

Acrylic Resins↗
PubMed1995

Revelations from a meta database system on environmental health problems.

Harmful effects of environmental pollution to the health status of population is well-known to ecologists and experts on health sciences. However, prevention and protection against such direct environmental hazards to save, or, in a worse case, re-establish the ecological balance are anything but successful. It is true, even if modern monitoring and measuring technology, adequate information systems, and related data bases are available. Precision of measurements and surveys, assessment and evaluation of the relationship between component elements of negative environmental effects on one the one hand, and general health conditions of the population on the other, could be increased by applying methods of informatics i.e., if we carry out a preliminary and professional analysis of the already existing information property. A useful tool for such activities could be the creation and maintenance of an integrated meta-type data base. It is a set sorted by a causal relations group of information that is collected from several databases of different origin, as pre-defined by the task. Our task was to systematize valuable information collected from different fields of science and research (competencies), to compare them with international standard databases, and thus, to discover new inter-relations, create new values. As an input, one could envisage a network of satellite data bases evaluating relevant results of scientists and research institutions. The main database itself could contain standard national and international information on environmental health care. The output of the system could be relational analysis produced by the meta-system on the basis of results provided by the satellite systems. Thus, frequently, even without carrying out a particular survey, one could already suspect that certain environmental health hazards exist, or plan and implement certain measurements and surveys in a more precisely targeted way. An unlimited number of local satellite workstation modules of experts and research institutions may be linked to the meta database. Information property created as a result of special analysis and annotation might create a knowledge basis for free access by participants. Thus not only would their scientific backgrounds be strengthened, but services would also be provided by the meta database which could be diversified continuously. The satellite systems, the sorting and retrieval functions of the database, and its graphical services would provide a loose but flexible micro-computer system that could be linked together by autonomous or networked workstations. Our system is written on FoxPro and uses FoxGraph. At a medium level of capacity, it requires 1 MB free RAM and 14-16 MB fixed memory. The system already shows a certain specialization: the 'PubHealth' system from general issues of environmental health care leans towards problems related to sub-toxic long term effects and correlations to health insurance risk assessment (cost-benefit, risk-benefit analysis). However, new issues are also emerging when experts wish foremost to utilize the philosophy of the system (e.g., epidemiological mental-hygienic surveys related to life style and social status).

Computer Communication Networks↗
PubMed1995

The main elements of the information system of the National Stroke Program (Smart Card - Telecommunication - Knowledge Bases).

The mortality of stroke in Hungary is 208 out of 100,000 inhabitants, which is very high in an international comparison. The age-group most in danger is between 35 and 50. There are 40-50 thousand hospital admissions each year because of stroke, the majority of them are unexpected crisis cases. In 1992, the government announced the National Stroke Program, which includes prevention, emergency, acute treatment and rehabilitation. Simultaneously with the medical-professional program, the National Stroke Program Information System (NSPI) has also been launched. Its aim is the direct backing up of the medical activity, the aiding of epidemiological tasks and preventive follow-up of patients. The system consists of an interactive database network in that it can guarantee accessibility, thus making every endeavour to assist in solving medical-professional problems with the help of modern information technology (smart care, telecommunication-device, etc.).

Adult↗
PubMed1995

The D3 receptor and its relevance in psychiatry.

A large fraction of neurotensin neurons in the ventromedial shell subdivision of nucleus accumbens express D3 receptors. Blockade of D2/D3 receptors by antipsychotic agents paradoxically decreases neurotensin gene expression in these neurons whereas it enhances it in other striatal areas expressing the D2 receptor. This suggests that D2 and D3 receptors mediate opposite actions of dopamine. In support of this view low doses of nafadotride, a novel D3 receptor-preferring antagonist, enhances locomotor activity in rodents, a behavioral response opposite to that of current neuroleptics. The action of D3 receptor-preferring agonists was characterized by the mitogenic response they elicit in transfected NG 108-15 cells. Finally, gene expression of the D3 receptor is in opposition to that of the D2 receptor, being decreased by denervation and unaffected by chronic blockade by neuroleptics.

Antipsychotic Agents↗
PubMed1994

The human cardiac mast cell: localization, isolation, phenotype, and functional characterization.

We have isolated and characterized the human cardiac mast cell (CMC) and compared this novel mast cell (MC type with MC obtained from uterus, skin, and lung. Heart tissue was obtained from 14 patients with cardiomyopathy (CMP, heart transplantation). CMC were isolated by enzymatic digestion using collagenase, pronase-E, hyaluronidase, and DNAse. Substantial amounts of CMC (0.5% to 1.5% of isolated cells) were found in the atrial appendages but not in ventricular digests or other sites of the heart (< 0.1%). In situ staining of atrial tissue revealed the presence of CMC in the myocardium (2.16 +/- 0.7 MC/mm2), endocardium (2.24 +/- 0.9 MC/mm2), and epicardium. As assessed by combined toluidine blue/immunofluorescence staining with monoclonal antibodies (MoAbs), isolated CMC expressed surface IgE, the receptor for stem cell factor (c-kit receptor/CD117), the p24 antigen (CD9), the Pgp-1 homing receptor (CD44), the pan leukocyte antigen (CD45), and the ICAM-1 antigen (CD54). CMC were not recognized by MoAbs to lymphocyte function associated antigen 2 (LFA-2; CD2), T-cell receptor (TcR; CD3), T4 antigen (CD4), LFA-1 alpha-chain (CD11a), C3biR alpha-chain (CD11b), CR4 alpha-chain (CD11c), LPS-R related Ag (CD14), 3-FAL/x-hapten (CD15), Fc gamma RIII (CD16), lactosylceramid (CDw17), the B-cell antigen CD19, or CR1 (CD35). In situ expression of leukocyte antigens on CMC was demonstrable by indirect immunoperoxidase staining technique and double-labeling immunohistochemistry. Almost all CMC (90%) reacted with MoAbs against tryptase and chymase and thus were MCTC. Cardiac mast cells were also stained by the heparin-binding dye Berberine sulfate and expressed measurable amounts of histamine (4.6 +/- 1.4 pg per cell). Cross linking of either IgE receptor or SCF receptor (c-kit) on CMC resulted in histamine secretion (non-specific release: < 6% of total histamine, alpha IgE induced: 12% to 52%; SCF-induced release: 9% to 18%), whereas neither substance P (a skin MC agonist) nor the basophil agonist FMLP showed an effect on CMC. Together, the CMC is an MCTC primarily located in the appendage of the atrium. This novel type of MC exhibits surface membrane antigen and functional properties similar to those of lung and uterus MC.

Antibodies, Monoclonal↗
PubMed1994

[Ambulatory blood pressure determination].

Recent studies have confirmed that the mean blood pressure levels recorded during ambulatory monitoring are lower than the levels measured by the standard cuff method, possibly due to the "white coat" effect which involves as many as 25 to 30% of the total hypertensive population. In addition, ambulatory blood pressure monitoring is particularly useful to evaluate the day/night cycle. Loss of the normal decrease in blood pressure at night occurs in certain types of secondary hypertension and can be revealed by ambulatory monitoring. The importance of the morning peak in determining prognosis in patients suspected of having hypertension is illustrated by the large number of cardiovascular events which occur during this period. There is also a close correlation between the mean 24-hour blood pressure and cardiovascular prognosis. Studies have demonstrated that the loss of the circadian rhythm or the mean 24-hour blood pressure are significantly correlated with type I diabetes mellitus, the risk of cerebral vascular events and left ventricle hypertrophy. Ambulatory monitoring is also a particularly useful method in clinical trials. Reproducible results can be obtained in the same individual and there is no placebo effect, making it possible to reduce the number of participants and thus raise the statistical power of the test. Ambulatory monitoring can also modify management decisions as found in a recent survey conducted in the United States demonstrating the impact on the treatment of hypertension. For 30 to 40% of the hypertensive patients, therapeutic management was different after ambulatory monitoring than after conventional cuff measurement. Standardization will be the next step in the widespread use of ambulatory blood pressure monitoring.

Blood Pressure Monitoring, Ambulatory↗
PubMed1994

Thigmotaxis as an index of anxiety in mice. Influence of dopaminergic transmissions.

When mice are introduced into an open-field, they are inclined to explore mainly the peripheral zone of this open-field. This tendency to remain close the walls, called thigmotaxis, decreases gradually during the first minutes of exploration. We have considered the degree of thigmotaxis during this period of decrease as an index of anxiety in mice. This hypothesis has been validated with several reference anxiogenic drugs (dexamphetamine, pentylenetetrazole, yohimbine, idazoxan) which increased thigmotaxis; and with anxiolytic drugs (buspirone, phenobarbital), which reduced it. On this test the selective or non-selective indirect dopamine agonists GBR 12783, dexamphetamine and cocaine induced an increase of thigmotaxis. Finally, the simultaneous involvement of D1 and D2 dopamine receptors has been evidenced in the anxiogenic-like effect associated with an increase of dopaminergic transmissions.

Adrenergic alpha-Antagonists↗