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Biomedical subjects

P Simon

Publications and source records attributed to P Simon.

At least 235 records · Page 13Linked to original sources
PubMed1993

[Multiple perforation in cryogenically preserved bone allografts. Comparative histological and microradiographic study of perforated and non-perforated allograft in sheep].

Incorporation of massive cortical bone allografts in the human is slow and remains incomplete. Late biopsies of implanted allografts or histological studies of explanted allografts always show the partial substitution of necrotic bone by new bone from the host. The aim of the present study was to evaluate the value of drilling the massive deep-frozen cortical allografts in order to induce osteogenesis. Thirteen sheep were operated on and a standard segment of the proximal ulna was removed and the gap filled either by an unperforated allograft or by a perforated one. Based on histological and microradiographic examination, a complete substitution of the perforated allografts was observed but in this model no statistically significant difference was observed between perforated and unperforated allografts. Further study is needed to assess the effect of the perforations.

Angiography↗
PubMed1993

A possible explanation for the multiple polyadenylation sites in transcripts coding for a winged-bean leghemoglobin.

Five different copy DNA clones coding for the same leghemoglobin were isolated from a winged-bean (Psophocarpus tetragonolobus L.) nodule library. Although identical in sequence, they each possess a different side of polyadenylation located 93-128 nucleotides downstream of two overlapping AAUAAA putative signal sequences. By analysis of the untranslated 3' ends, a potential mRNA secondary structure can be predicted which could explain the observed polyadenylation heterogeneity. The structure is a size-variable hairpin, creating a net topological distance of 25-27 nucleotides between the canonical signal sequence and the different polyadenylation sites observed. We suggest that this type of variable secondary structure could be one among other causes that determines the apparent flexibility of plant polyadenylation. It could also confer particular properties to the mRNA in relation to stability, translation efficiency and-or nuclear export.

Base Sequence↗
PubMed1993

Anxiogenic-like effects induced by stimulation of dopamine receptors.

We considered the increase in latency for entering into a white-lightened compartment from a black one as an index of anxiety for Swiss albino mice. This has been validated with several reference anxiogenic drugs [pentylenetetrazole, yohimbine, dexamphetamine, and methyl-beta-carboline-3-carboxylate (beta-CCM)]. On this test, the effects of various indirect or direct dopamine (DA) agonists have been investigated, as well as the respective involvement of D1 and D2 dopamine receptors. Dexamphetamine, the specific DA uptake inhibitor 1-[2-(diphenylmethoxy)-ethyl]4-(3-phenyl propenyl)-piperazine (GBR 12783), and the mixed DA/norepinephrine uptake inhibitor N-[1-(2-benzo(b)thiophenyl)-cyclohexyl]piperidine (GK 13) dose dependently increased the entering latency. This effect was shared by the D2 DA agonist RU 24926. The partial agonist of D1 DA receptors SK&F38393 had a significant although moderate efficacy. Their association led at best to an additive synergy. The antagonist of D1 DA receptors SCH23390 shortened the entering latency. The anxiogenic effect of GBR 12783 was antagonized by haloperidol and SCH23390. It is concluded that an anxiogenic-like effect is linked to an increase in dopaminergic transmission involving both D1 and D2 dopamine receptors.

Animals↗
PubMed1993

Pulmonary autograft valve replacement in the dilated and asymmetric aortic root.

Pulmonary autograft aortic valve replacement is the only technique for implantation of a biologic, vital and thus nondegenerating valve. The technique of root replacement overcomes problems of asymmetric aortic roots and reduces the risk of malalignment, but bears the risk of dilatation. We have performed pulmonary autograft aortic root replacement in 20 patients (mean age 22 years, range 5-38). Twelve presented with aortic incompetence, 3 with stenosis and 5 with combined defects. Initially roots were implanted just supraannularly with two running suture lines. As the neo-aortic roots gradually dilated, we started to implant autografts intraannulary, but still one valve dilated and aortic incompetence (AI) increased from grade I to II. Consequently the remaining aortic wall was wrapped around the new root and the composite subsequently was reinforced by a circular absorbable mesh. In addition, the aorta and pulmonary valve were exactly sized and the aortic root was reduced by commissuroplasty stitches up to 6 mm in diameter in seven cases. The ventricular size decreased in all patients 10 days after surgery, the left ventricular end-diastolic diameters (LVEDD) from 58 +/- 12 to 52 +/- 10 mm (P = 0.0002; paired t-test) and left ventricular end-systolic diameter (LVESD) from 41 +/- 12 to 36 +/- 10 mm (P = 0.008), but the contractility did not change significantly (fractional shortening from 31 +/- 9% to 30 +/- 9%). The diameter of the new aortic ring increased for the supraannular position but size matching and the intraannular valve position reduced the new ring size significantly (P = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

[Prevalence of arterial hypertension in the Brittany population].

The epidemiology of arterial hypertension was studied from 1988 to 1991 in a region in the west of France comprising 500,000 inhabitants. Prevalence of arterial hypertension was calculated to 16.2%, significantly higher in men than in women (22.5% vs 11.2%).

Adolescent↗
PubMed1993

Arterial to end-tidal CO2 tension difference after bilateral lung transplantation.

OBJECTIVES: To assess ventilation/perfusion mismatch with high ventilation/perfusion ratios (i.e., alveolar deadspace) and to assess capnography as a noninvasive method of monitoring ventilation after bilateral lung transplantation. DESIGN: Clinical, prospective study. Repeated-measures analysis of variance was done to assess the time course of the arterial to end-tidal CO2 tension difference. SETTING: University hospital operating theater and intensive care unit. PATIENTS: Seven consecutive patients aged 25 to 64 yrs who underwent bilateral lung transplantation for end-stage lung disease. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The arterial to end-tidal CO2 tension difference was determined using infrared absorption capnography during postoperative day 1. Measurements were done at 10 mins, and at 1, 3, 12, and 24 hrs after bilateral lung transplantation (timing of measurements determined from the time when both lungs were perfused and mechanically ventilated). An arterial to end-tidal CO2 tension difference, ranging from 6 to 21 torr (0.8 to 2.8 kPa), mean 16 +/- 5 torr (2.2 +/- 0.7 kPa), was observed immediately after the transplantation. This difference rapidly decreased to 9 +/- 4 torr (1.2 +/- 0.6 kPa; p < .01) after 3 hrs and to 5 +/- 3 torr (0.6 +/- 0.4 kPa; p < .01) after 24 hrs. CONCLUSIONS: Our data suggest marked alveolar deadspace ventilation immediately after bilateral lung transplantation. The presence and rapid improvement of this ventilation/perfusion mismatch may reflect the presence of ischemia-reperfusion lung injury and its improvement in the first hours of reperfusion. In five of seven patients, capnography was not a good measure of PaCO2 during the first hours after bilateral lung transplantation.

Adult↗
PubMed1993

Ventilatory effects of pneumoperitoneum monitored with continuous spirometry.

Inspiratory and expiratory tidal volume, peak and plateau airway pressure, compliance of the respiratory system, pressure-volume and flow-volume loops were monitored continuously and recorded in seven women undergoing laparoscopy with carbon dioxide insufflation to an intra-abdominal pressure of 1.6 kPa. All patients were anaesthetised using a total intravenous technique and a constant minute ventilation was maintained. Peak airway and plateau airway pressures increased by 50% and 81% respectively, whilst the compliance of the respiratory system decreased by 47% during the period of increased intra-abdominal pressure. Following release of the pneumoperitoneum, peak and plateau pressures remained elevated by 37% and 27% respectively, and the compliance was 86% of the pre-insufflation value. On-line monitoring of respiratory volumes, pressures and compliance may be helpful during general anaesthesia for laparoscopic procedures to avoid the potential harmful effects of increased airway pressures occurring with increased intra-abdominal pressure.

Adult↗
PubMed1993

How frequent are hepatitis B virus markers in adult patients with glomerular diseases in a low endemic country? A French study from Paris and Saint-Brieuc.

In order to appreciate the frequency of hepatitis B virus (HBV) infection in patients with glomerular diseases in France, a low endemic country, we reviewed the series of patients biopsied in the years 1983-1989 in 2 departments of nephrology differing by the characteristics of the population. In Saint-Brieuc, where the population is almost exclusively Caucasian, with nearly no immigrant, HBsAg was not detected in any of the 86 patients. In Paris, a large number of patients come from highly or intermediately endemic regions. HBsAg was detected in 3 of 209 patients, 2 of the 75 patients with membranous nephropathy and 1 of the 32 patients with minimal-change nephrotic syndrome. These patients came from Africa and Asia. Therefore, in low endemic countries, the role of HBV infection in the etiology of glomerulonephritis is minimal. But, because of the late severity of the disease, screening remains essential in patients belonging to the high-risk groups.

Adolescent↗
PubMed1993

[Genetic and environmental factors implicated in recurrent calcium lithiasis].

In this prospective study, we compared the frequency of some genetic and environmental factors possibly implicated in the occurrence of calcium stone disease. A group of 439 patients (258 males and 181 females) with one episode of calcium stone was compared to a group of 191 patients (131 males and 60 females) with recurrent calcium stone disease. Population with stones was also compared to control population (n = 78, 40 males and 38 females) matched to age. Major results were as follow: 1) Family history of urinary calculi was more frequent in patients than in controls (28.4% vs 9%, p < 0.01). No difference was observed between patients with one episode and those with recurrent episodes (27% vs 31%, ns). 2) The recurrence was earlier in female than in male, so that in female with family history of urinary calculi (p < 0.05). 3) Mean plasma levels of 1-25OH2D3 was significantly higher in patients with family history than in controls (60% vs 38%, p < 0.01) 5) Restricted calcium diet (< 400 mg per day) was more often observed in patients than in controls (31% vs 14%, p < 0.05) and the most significant difference was found in patients with recurrent calcium stones.

Adult↗
PubMed1993

[Short and long term complications of lithotripsy on renal function].

Today, most stones can be removed by minimally invasive means. Extracorporeal Shock Wave Lithotripsy (ESWL) is the preferred form of treatment for symptomatic upper ureteral and renal calculi less than 2 cm a diameter. The short and long term complications of ESWL are underestimated. Thus, ESWL may cause renal trauma and such trauma may induce later hypertension. In this retrospective study, we reviewed the frequency of deleterious effects of ESWL in 45 patients who had undergone ESWL from January 1988 to September 1989. Short-term complications were macroscopic hematuria (15%), lumbar pain (11%) and peri- or intrarenal hematomas (4.4%). Two years later CT scan was performed in 20 patients. It was normal in 7 (35%). In others, it shown a recurrence of stone in 8 (40%) and a focal scarring in 5 (25%). Only 1 out of 43 patients had developed hypertension.

Adult↗
PubMed1993

Indices of adequate dialysis in patients hemodialyzed with AN 69 membrane.

The objective of this study was to evaluate the incidence of morbidity (at least one hospitalization) during the first twelve months of hemodialysis (thrice weekly for 4 hours) in 54 (27 males and 27 females) sex and age matched patients, of whom 32 were treated with AN 69 (M/F = 13/19, 62 +/- 14 years) and 22 with Cuprophan (M/F = 14/8, 61 +/- 14 years). Patients were classified according to the value of TAC urea during the period under study: constantly superior or equal to 20 mmol/liter in Group A (high TAC urea) or inferior to 20 mmol/liter in Group B (low TAC urea). Dialysis quantification (Kt/V) and estimation of the patient's protein catabolic rate (PCR) were based on measurement of the midweek pre- and post-dialysis blood urea nitrogen. In the patients of Group B, incidence of morbidity was significantly increased when age was over 50 years and when AN 69 membrane was used (P < 0.02). Furthermore, in Group A, the risk of hospitalization was significantly higher in patients treated by Cuprophan than in those treated by AN 69 (P < 0.02). The survival rate was also studied. Better survival (70%) at four years was observed in patients with high TAC urea who were treated by AN 69. The difference was highly significant with the survival rate (22%) in patients with high TAC urea who were treated by Cuprophan (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗