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Biomedical subjects

M David

Publications and source records attributed to M David.

At least 199 records · Page 11Linked to original sources
PubMed1998

Intermediate follow up of the TEKNA bileaflet valve.

BACKGROUND AND AIM OF THE STUDY: The study aim was to collect intermediate clinical data on the TEKNA bileaflet valve. METHODS: This nine-center clinical study involved 884 patients implanted between June 1990 and October 1993. The population consisted of 522 (59.0%) males and 362 (41.0%) females. Mean age at implant was 59.1 +/- 11.8 years (range: 14.7 to 88.4 years). Indication for valve replacement was dependent on the position: stenosis was the predominant reason in the aortic position; regurgitation was more pronounced for the mitral position. A total of 261 (29.5%) patients underwent concomitant procedures. Mean follow up is 2.7 +/- 1.2 years; total follow up is 2386.1 patient-years (pt-yr). RESULTS: Total operative (< or = 30 days postoperative) mortality rate was 3.7%; seven patients (0.8%) died due to valve-related causes. Total postoperative (> 30 days postoperative) mortality rate was 2.5%/pt-yr and included a valve-related mortality rate of 1.1%/pt-yr. The following valve-related complication rates (%/pt-yr) were reported for the long-term postoperative period: thromboembolism 0.6; valve thrombosis 0.3; bleeding events 1.5; non-structural deterioration 0.6; and endocarditis 0.4. No structural valve deterioration was reported. Actuarial freedom at four years was: overall survival rate 86.9 +/- 1.4%; valve-related survival rate 94.7 +/- 1.0%; freedom from thromboembolism 96.8 +/- 0.9%; valve thrombosis 99.3 +/- 0.3%; endocarditis 98.5 +/- 0.5%; bleeding events 94.3 +/- 1.0%; and non-structural deterioration 98.2 +/- 0.6%. CONCLUSIONS: The data indicate that observed mortality is due mainly to non-valve-related disorders. Risk of thromboembolic and bleeding events was low (0.9%/pt-yr and 1.5%/pt-yr, respectively). We conclude that this valve is safe and efficacious for use.

Actuarial Analysis↗
PubMed1998

[The prognosis of surgery on the elderly. Proposal for a parametric evaluation].

BACKGROUND AND AIMS: To data there are no preoperative systems of evaluating surgical risk specifically in geriatric patients. Given that it was thought useful to formulate a score-based prognostic system for these patients based on surgical risk, the authors collected a wide range of preoperative data with the aim of identifying the easily determined variables. METHODS: While data from other hospital centres are in the process of being collected, the authors report the data for 122 over 65-year-old patients who underwent elective surgery up until 30-1-1996 out of a total of 329 hospitalized patients. In addition to a wide series of objective, laboratory and instrumental data, the study also took into account the pathology requiring to surgery, any associated morbid conditions, psychic and social conditions, the type of surgery and local and/or general postoperative complications. RESULTS: Hernia of the abdominal wall were found to be the most frequent cause of surgery (41 cases), followed by 27 neoplasias of various organs and biliary lithiasis (20 cases). Cardiovascular diseases were the most common associated pathologies (85 patients). A total of 13 major and 80 medium operations were performed, including 16 cholecystectomies. Among the general complications, an altered acid-base balance was found in 7 patients. Two deaths were recorded within 30 days of surgery. When the data collection is complete, the results will be analysed statistically in order to obtain a numerical calculation of the coefficients of risk correlated to the individual variables. CONCLUSIONS: This will enable the criteria of operability to be broadened, thereby allowing surgery to be performed in those patients who are currently excluded merely on the basis of the personal judgement of the surgeon and anesthetist.

Aged↗
PubMed1998

[Long-term follow-up of anatomic heart transplantation. Apropos of 60 patients with a mean follow-up of 36 months].

The aim of this study was to collect different problems seen in long-term evolution of patients who had anatomical cardiac transplantation and to compare with those seen in patients with standard transplantation. During the mean follow-up of 36 months, we analysed different data of 60 patients mean aged 51, who underwent anatomical cardiac transplantation. Six patients (10%) died within the 30 days after surgery. No patient needed the use of permanent pacemaker. Echocardiographic examination found normal atrial shape. One month after surgery, echocardiography described 16 tricuspid regurgitations (22.66%) and 8 mitral regurgitations (13.33%), 1 year later, there was respectively 13.33 and 6.66% tricuspid and mitral regurgitation. We had 8 late deaths: 1 sudden death, 2 chronic rejections, 1 pancreatitis and 4 cancers. The survival analysis pointed out 84% at 1 year, 80 at 2 years, 78 at 3 years and 73 at 5 years. Six months after surgery, 80% of patients were treated for high blood pressure; 85% had serum creatinine level equal or superior to 13 mg/L, with mean serum ciclosporin at 130 ng/mL. At the 3rd month, 6 endomyocardial biopsies were equal or superior to grade 2 rejection (International Society for Heart Transplantation). Between the 3rd and 12th month, 3 endomyocardial biopsies were equal or superior to grade 2 rejection, and the same between the 12th and 24th month. The infections rate was 0.8 episode per patient. Long term follow-up of anatomical cardiac transplantation faces the same problems as in standard cardiac transplantation. It is better to perform anatomical cardiac transplantation because of its early postsurgical advantages. Long term care is the same as in standard cardiac transplantation.

Actuarial Analysis↗
PubMed1998

Pregnancies following liver transplantation--how safe are they? A report of 19 cases under cyclosporine A and tacrolimus.

The number of pregnancies following liver transplantation is increasing due to better patient and graft survival and quality of life. Out of 156 women of a reproductive age, there were 19 pregnancies in 16 women, 12 on CsA and seven on tacrolimus, which occurred between 7/92 and 1/97. The median age of the women was 27.9 yr, median time after transplantation 33 months. There were four spontaneous and two induced abortions in the first trimenon. Ten women delivered ten healthy babies; three newborns had problems (alcoholic embryopathy due to recurrent alcohol abuse of his mother, pneumonia, weight < 2000 g). In eight women mostly mild complications were observed, such as hypertension (n = 5), nonspecific elevation of liver enzymes (n = 2), infection (n = 3) and premature labor (n = 1). Mean gestational age was 39 wk and mean birth weight 2900 g. One case of prematurity and three cases of growth retardation occurred. Cesarean sections were performed in 7 patients (54%) for maternal hypertension (n = 2), presumed fetal hypoxia (n = 4) and breech position (n = 1). All children are normally developed, the oldest being 5 yr old. Although experience with tacrolimus is limited, pregnancies following liver transplantation carry an acceptable risk if carefully monitored by an experienced team of transplant surgeons and obstetricians.

Adult↗
PubMed1997

Engrafted human T and B lymphocytes form mixed follicles in lymphoid organs of human/mouse and human/rat radiation chimera.

BACKGROUND: We recently described a new approach that enables the generation of human/mouse chimera by adoptive transfer of human peripheral blood mononuclear cells into lethally irradiated normal strains of mice or rats, radioprotected with bone marrow from donors with severe combined immune deficiency. In such human/mouse chimera, a marked humoral response to recall antigens, as well as a significant primary response to keyhole limpet hemocyanin, has been generated. METHODS: In the present study, the organ distribution of the engrafted human cells in the human/mouse and human/rat chimera was investigated by immunohistochemistry. RESULTS: Our results show that the T cells seem to be distributed throughout the reticular endothelial system, almost behaving like particles without any homing specificity. The B cells, however, can barely be found in internal organs, such as the liver or the pancreas, and are concentrated in the secondary lymphoid system (e.g., spleen, lymph node, and nonencapsulated lymphoid tissue). The B cells, together with the engrafted human T cells, form mixed lymphoid follicles. CONCLUSIONS: The different homing patterns exhibited by the T and B lymphocytes indicate that the homing receptors on human B cells might be cross-reactive with their mouse counterparts, in contrast to the human T cells, which seem to be unable to interact with the mouse homing receptors. The presence of human B and T lymphocytes in close proximity to each other in the lymphoid tissues is in accordance with the ability of human/BALB radiation chimera to mount significant primary human antibody responses.

Adoptive Transfer↗
PubMed1997

A model for human B-chronic lymphocytic leukemia in human/mouse radiation chimera: evidence for tumor-mediated suppression of antibody production in low-stage disease.

B-chronic lymphocytic leukemia (BCLL) is a lymphoproliferative disease that is characterized by clonal expansion of CD5+ B cells. BCLL is associated with secondary immunodeficiency and hypogammaglobulinemia. It has been suggested that T-cell dysregulation may play a role in the hypogammaglobulinemia and in the increased incidence of autoimmunity in BCLL patients. We attempted to transfer human peripheral blood mononuclear cells (PBMC) from BCLL patients in different stages of the disease into immunodeficient mice. PBMC from BCLL patients in stage 0, stages I to II, and stages III to IV were transplanted into the peritoneal cavity of lethally irradiated Balb/c or beige/nude/Xid (BNX) mice radioprotected with bone marrow (BM) from severe combined immunodeficiency (SCID) mice. Different engraftment profiles were found in the chimeric mice 2 weeks after transplantation of PBMC according to the disease stage of the BCLL donors. Infusion of PBMC from donors in stage 0 led to marked engraftment of human T cells, whereas the human tumor cells could hardly be detected. In contrast, chimeric mice receiving PBMC from patients in stage III to IV disease exhibited engraftment with a dominance of tumor cells, compared with a miniscule level of T cells. The ability of the engrafted cells to produce human Ig was also found to be correlated with the disease stage of the donor, although all donors had the same magnitude of hypogammaglobulinemia. Total human Ig production in the chimeric mice was normal in mice receiving PBMC from donors in stage 0, whereas in chimeric mice engrafted with PBMC from donors in stages III to IV almost no human Igs could be detected. This differential reconstitution of antibody production in the mouse model according to the stage of the patient's disease will allow further studies on possible cellular interactions between malignant and immune cells in BCLL.

Adoptive Transfer↗
PubMed1997

A thyroxine dosage of 8 micrograms/kg per day is appropriate for the initial treatment of the majority of infants with congenital hypothyroidism.

UNLABELLED: The adequate L-thyroxine dosage for the initial treatment of infants with congenital hypothyroidism is a subject of controversy. Some recommend higher dosages (> 10 micrograms/kg/day) to ensure adequate levels, while others advocate lower dosages to permit normalisation of thyroid status. The aim of this study was to evaluate the results of a treatment strategy using an initial dosage of 7.5-8.0 micrograms/kg per day, TSH measurements being taken at 15 and 30 days of treatment. Fifty one newborns infants with primary congenital hypothyroidism detected by neonatal screening were treated with the same therapeutic strategy. A mean L-thyroxine dosage of 7.9 micrograms/kg per day at the onset of treatment and 6.6 micrograms/kg/d at 2 months, normalised the FT4 and FT3 levels at 15 days in 100% and TSH levels at 2 months in 90% of cases. Many patients showed elevated levels of FT4 and a systematic higher initial dosage could expose many infants to a dangerous hyperthyroidism. Patients with abnormal TSH levels at 2 months already had higher TSH levels in the first 8 weeks of life and, despite higher L-thyroxine dosage, also exhibited lower FT4 and FT3 levels. These patients who needed an early increase in dosage had already shown a more profound ante and neonatal hypothyroidism. This subgroup of patients require a higher dosage of thyroxine and early assessment of FT4, FT3 and TSH levels are required for optimum dosage choice. CONCLUSION: Even though a subgroup of patients may require a higher dosage of L-thyroxine, an initial dosage of 7.5-8.0 micrograms/kg per day, with an early assessment of FT4, FT3, and TSH levels, is adequate for the treatment of the majority of infants with congenital hypothyroidism.

Congenital Hypothyroidism↗
PubMed1997

Juvenile granulosa cell tumor of the ovary in infants: a clinicopathologic study of three cases and review of the literature.

The clinical and pathological features of three cases of juvenile granulosa cell tumors occurring in infants were studied. Precocious pseudopuberty developed in two patients and acute abdominal symptoms related to the rupture of the tumor developed in one. Surgery was the only treatment in each case and no adjuvant therapy was delivered. No patient experienced relapse. Histological examination showed a predominantly diffuse pattern with prominent luteinization. Call-Exner bodies were absent. Two tumors had multilocular thin walled cysts containing large amounts of estradiol, the third one contained rudimentary microfollicles. The prognosis of juvenile granulosa cell tumors in infancy appears more favorable than those occurring in older patients. No case of tumor recurrence has been reported in infancy so far. Surgery appears to be the state-of-the-art treatment of these tumors and additional therapy (chemotherapy or radiotherapy) must be discussed with caution, even in advanced stages.

Female↗
PubMed1997

A method using a liquid chromatographic-electrospray-mass spectrometric assay for the determination of antimigraine compounds: preliminary pharmacokinetics of MDL 74,721, sumatriptan and naratriptan, in rabbit.

MDL 74,721 (I), sumatriptan(II) and naratriptan(III) are new 5-HT1-like agonists that have potential as a novel treatment for migraine. Liquid chromatographic-electrospray-mass spectrometric (LC-ESI-MS) assay have been developed to compare the pharmacokinetics of these three antimigraine compounds. The concentration of each parent drug was determined using a solid-phase extraction method and LC-ESI-MS analysis demonstrating the high sensitivity and specificity of the methods down to subnanogram levels in rabbit plasma samples. Pharmacokinetic parameters evaluated after administration of single intravenous and oral doses were very similar and the ANOVA analysis did not show any statistically significant differences for t1/2, Cmax, V or AUC (normalised). The pharmacokinetic parameters showed short t1/2 (range 1.14-1.9 h) either after intravenous (i.v.) or oral (p.o.) administration and high total body clearance (CL) after the p.o. dose both probably due to extensive and rapid metabolism of the parent drugs as suggested by the low values for bioavailability (range 13.4-22.8%).

Administration, Oral↗
PubMed1997

Is the Parsonnet's score a good predictive score of mortality in adult cardiac surgery: assessment by a French multicentre study.

OBJECTIVE: Parsonnet proposed a preoperative score ("initial Parsonnet's score", which predicts the hospital mortality of adult cardiac surgery. This score was then modified by including several risk factors used in the 'SUMMIT' system ("modified Parsonnet's score", 44 variables). We wanted to assess the predictive value of these two scores in a French surgical population. METHODS: From December 1992 to April 1993, in France, we organised a prospective multicentre study on adult cardiac surgery mortality and morbidity. Data on 6649 patients were included. We analysed statistically the predictive value of each risk factor and of the two scores on mortality and morbidity at one month. RESULTS: Only 6 of the 15 variables of the initial Parsonnet's score and 19 of the 44 variables of the modified Parsonnet's score significantly influence hospital mortality. Both scores are able to predict hospital mortality and severe morbidity, but the modified Parsonnet's score has the best predictive value (initial Parsonnet's score: odds ratio by point of score = 1.01, area under the roc curve = 0.64; modified Parsonnet's score: odds ratio by point of score = 1.05, area under the roc curve = 0.70). CONCLUSIONS: This study shows that the Parsonnet's scores are predictive, but that these scores remain imperfect: many risk factors are non significant, the initial Parsonnet's score has a moderate predictive value, and the modified Parsonnet's score is too complex (44 variables). Thus, we have built a new score for cardiac surgery in French adults.

Adult↗
PubMed1997

Human/mouse radiation chimera generated from PBMC of B chronic lymphocytic leukemia patients with autoimmune hemolytic anemia produce anti-human red cell antibodies.

Previous studies performed in our laboratory have shown that B-CLL cells are involved in the production of anti-red cell auto-antibodies, providing a possible mechanism for the autoimmune hemolytic anemia occurring during the course of B-CLL. In order to confirm this hypothesis, we attempted to transfer human B-CLL with AIHA to immunodeficient mice. Peripheral blood mononuclear cells (PBMC) from 11 B-CLL patients suffering from AIHA were transplanted into the peritoneal cavity of lethally irradiated Balb/c mice reconstituted with SCID bone marrow. Chimeric mice generated from PBMC of these patients (in stage III-IV of the disease) exhibited an engraftment profile with dominance of tumor cells and minuscule levels of T cells. Eighty-five percent of the chimeric mice generated from 10 out of the 11 B-CLL patients with Coombs'-positive AIHA, produced human Ig with anti-human red cell specificity as detected by indirect anti-globulin test. In addition, anti-red cell auto-antibodies were produced in 36% of chimeric mice generated from PBMC of Coombs'-negative B-CLL. In contrast, control experiments in which splenic cells from idiopathic AIHA or PBMC from normal donors were transplanted, failed to produce anti-RBC. This in vivo model further supports the relationship between the B cell expansion and the autoimmune hemolytic process.

Aged↗
PubMed1997

T-lymphocyte dependence of psoriatic pathology in human psoriatic skin grafted to SCID mice.

Considerable indirect evidence suggests that T lymphocytes have a role in the pathogenesis of psoriasis. The goal of this study was to directly test the ability of T cells to maintain psoriasis pathology. Psoriatic skin was transplanted onto SCID mice, which were then injected with autologous T cells. T cells were cultured from either psoriatic skin lesions or peripheral blood and injected intradermally or intravenously. Control SCID mice transplanted with psoriasis grafts were not injected with T cells. After 10 wk, control psoriatic skin grafts not injected with T cells lost many of the features of psoriasis. Injection of peripheral blood T cells was not able to maintain these psoriatic features. In contrast, the injection of T cells derived from psoriatic skin was able to maintain the psoriatic phenotype. Psoriatic features that were maintained included epidermal thickness and labeling index and expression of HLA-DR, involucrin, and ICAM-1, as well as loss of expression of filaggrin. Injection of skin infiltrating T cells into skin of normal donors on SCID mice did not induce changes of psoriasis. The ability of T cells from lesional skin, but not peripheral blood, to maintain psoriasis suggests that psoriasis is mediated by an autoantigen reactive T cell, which is present at a higher frequency in the psoriatic lesion.

Adoptive Transfer↗
PubMed1997

Lupus miliaris disseminatus faciei--the DNA of Mycobacterium tuberculosis is not detectable in active lesions by polymerase chain reaction.

There has been a controversy as to the origin of lupus miliaris disseminatus faciei (LMDF). It was originally thought to be associated with tuberculosis, due to its histopathological similarity. Recently, this association has been doubted, although there remain reported cases of LMDF associated with Mycobacterium tuberculosis. Three patients with the clinical and histopathological features of LMDF are described. Skin from these patients was analysed by polymerase chain reaction (PCR) using two different oligoprimers for the detection of 123 bp and 165 bp DNA fragments specific for M. tuberculosis complex. With these two PCR systems, no M. tuberculosis DNA was detected in any of the LMDF patients. It was present in all positive controls and absent in all negative controls. In this study we could not demonstrate an association between LMDF and tuberculosis.

Adolescent↗
PubMed1997

Beta interferon and oncostatin M activate Raf-1 and mitogen-activated protein kinase through a JAK1-dependent pathway.

Activation of early response genes by interferons (IFNs) and other cytokines requires tyrosine phosphorylation of a family of transcription factors termed signal transducers and activators of transcription (Stats). The Janus family of tyrosine kinases (Jak1, Jak2, Jak3, and Tyk2) is required for cytokine-induced tyrosine phosphorylation and dimerization of the Stat proteins. In order for IFNs to stimulate maximal expression of Stat1alpha-regulated genes, phosphorylation of a serine residue in the carboxy terminus by mitogen-activated protein kinase (MAPK) is also required. In HeLa cells, both IFN-beta and oncostatin M (OSM) stimulated MAPK and Raf-1 enzyme activity, in addition to Stat1 and Stat3 tyrosine phosphorylation. OSM stimulation of Raf-1 correlated with GTP loading of Ras, whereas IFN-beta activation of Raf-1 was Ras independent. IFN-beta- and OSM-induced Raf-1 activity could be coimmunoprecipitated with either Jak1 or Tyk2. Furthermore, HeLa cells lacking Jak1 displayed no activation of STAT1alpha, STAT3, and Raf-1 by IFN-beta or OSM and also demonstrated no increase in the relative level of GTP-bound p21ras in response to OSM. The requirement for Jak1 for IFN-beta- and OSM-induced activation of Raf-1 was also seen in Jak1-deficient U4A fibrosarcoma cells. Interestingly, basal MAPK, but not Raf-1, activity was constitutively enhanced in Jak1-deficient HeLa cells. Transient expression of Jak1 in both Jak-deficient HeLa cells and U4A cells reconstituted the ability of IFN-beta and OSM to activate Raf-1 and decreased the basal activity of MAPK, while expression of a kinase-inactive form of the protein showed no effect. Moreover, U4A cells selected for stable expression of Jak1, or COS cells transiently expressing Jak1 or Tyk2 but not Jak3, exhibited enhanced Raf-1 activity. Therefore, it appears that Jak1 is required for Raf-1 activation by both IFN-beta and OSM. These results provide evidence for a link between the Jaks and the Raf/MAPK signaling pathways.

Animals↗
PubMed1997

Peripherally inserted central catheters in infants and children.

PURPOSE: To determine prospectively the feasibility, complications, and mid- and long-term advantages of peripheral insertion of central catheters in infants and children. MATERIALS AND METHODS: During a 15-month period between March 1995 and June 1996, a total of 285 catheter placement attempts were made to peripherally insert central catheters in 183 pediatric patients (89 boys, 94 girls). Phlebographic guidance was used, and the catheters were inserted below the elbow in 99% of cases. Catheter insertion was indicated for prolonged antibiotic therapy in 108 patients (158 catheter placement attempts), hematologic or oncologic care in 24 patients (40 attempts), total parenteral nutrition in 16 patients (46 attempts), and venous access for fluid or blood in 35 patients (41 attempts). The success rate and complications were recorded along with the indication, patient age, and duration of catheter placement. RESULTS: One hundred fifty-two of 158 (96%) catheter placement attempts were successful in outpatients (n = 108), 124 of 127 (98%) in hospitalized patients (n = 75), and 70 of 73 (96%) in patients aged less than 1 year. Infection and pericatheter venous thrombosis were the main complications and were seen in 17 of 276 (6%) and one of 276 (0.3%) catheter placement attempts, respectively. Catheter occlusion occurred in 23 of 276 (8%) catheter placement attempts. CONCLUSION: Peripheral insertion of central catheters was highly feasible in infants and children with this protocol. Such catheters were well tolerated in the pediatric population with a low frequency of complications.

Catheterization, Central Venous↗