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Biomedical subjects

P Dumont

Publications and source records attributed to P Dumont.

At least 19 recordsLinked to original sources
PubMed1992

Pleuropulmonary aspergilloma: clinical spectrum and results of surgical treatment.

From 1974 to 1991, 77 patients were admitted for pulmonary (55), pleural (16), or bronchial (6) aspergilloma. About 50% were asymptomatic. Sixty-three underwent operation. Pulmonary aspergillomas were operated on for therapeutic need in 26 and on principle in 18; the procedures were 28 lobar or segmental resections, 10 thoracoplasties, and 5 pleuropneumonectomies (1 patient had exploration only). Pleural aspergillosis was treated by operation on principle in 5 and for therapeutic need in 8 patients; 10 thoracoplasties, 1 attempt at pleuropneumonectomy, and 2 decortications were performed. All six bronchial lesions were operated on as a rule. Overall postoperative mortality was 9.5%. Major complications were bleeding (n = 37), pleural space problems (n = 24), respiratory failure (n = 6), and postpneumonectomy empyema (n = 4). All patients with pleural disease experienced complications. The outcome was better after lobar or segmental resection than after thoracoplasty (mortality, 6% versus 15%). Asymptomatic and nonsequellary pulmonary or bronchial aspergilloma also had an improved outcome. We conclude that operation is at low risk in pulmonary or bronchial locations in asymptomatic patients and in the absence of sequellae; the risk is high in symptomatic patients for whom operation is the only definite treatment. Pleuropneumonectomy should be avoided. Only symptomatic pleural aspergilloma should be operated on.

Adolescent↗
PubMed1992

Mutagenicity of nitroxyl compounds: structure-activity relationships.

Three piperidinoxyl radicals were found to be directly mutagenic in Salmonella typhimurium TA 100, one pyrrolidinoxyl compound had weaker activity, and two other pyrrolidinoxyl derivatives did not produce an increase of the spontaneous revertants. The tester strain TA 100 was selected in preliminary tests for its higher sensitivity compared to TA 98 and TA 102. The mutagenic activity of the three active compounds was abolished by partial reduction with ascorbic acid, suggesting that the mutagenicity was linked to the free radical nature of these compounds, and reduced in the presence of a cofactor supplemented rat liver subcellular fraction. The mutagenicity of the tested compounds was correlated to the resistance of the nitroxyl spin labels to reduction: the more reactive radicals were found to possess higher mutagenic activity.

Ascorbic Acid↗
PubMed1992

Evaluation of nonionic nitroxyl lipids as potential organ-specific contrast agents for magnetic resonance imaging.

Considering their intrinsic properties of accumulation in the hepatic tissue, we have synthesized nitroxyl-containing lipids as potential organ-specific contrast agents for magnetic resonance imaging (MRI). Their resistance to reduction by ascorbate and in liver homogenates, and their relaxivity in different media were investigated and compared to those of free carboxyl-Proxyl (3-carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl) and Tempamaine (4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl). With respect to the reduction rates by ascorbate, the lipid derivatives show the same well-known order of reactivity as carboxy-Proxyl and Tempamine, the five-membered nitroxyls being more stable than the six-membered compounds. However the binding of the piperidinoxyl compounds to the fatty acids confers to those lipid derivatives a markedly increased stability. Similarly, in liver homogenates, the nitroxyl lipids remained unchanged more than 20 min, contrarily to carboxy-Proxyl and Tempamine. The measurements of spin-lattice relaxation time (T1) in biological media have demonstrated a higher relaxivity of nitroxyl lipids, which can be related to their interaction with proteins. Tested in vivo, one of the synthesized compounds (0.75 mmol/kg) produced an enhancement of 44 +/- 12% of the hepatic signal 5 min after intraportal injection in T1-weighted images. The potential applicability of the other nitroxyl lipids as contrast agents for MRI was limited in the in vivo studies by an unexpected toxicity. Work is currently in progress to improve the therapeutic index of the present class of nitroxyl lipids.

Animals↗
PubMed1992

[Lobectomy extended to the main bronchus in the treatment of bronchial cancer (seventy-three cases)].

Sleeve allow excision of bronchial carcinoma in patients not able to functionally tolerate pneumonectomy. Our series consists of 73 patients operated over the last thirty years. Implantation of the bronchus was treated either by wedge resection or by complete resection followed by reimplantation. This procedure was performed for respiratory functional reasons in 39 cases (53%), on principle in 27 cases (37%) and in palliative indications in 7 cases (10%). The high perioperative mortality (6.8%) and morbidity (20%) were related to bronchovascular complications which were eliminated over the last decade. Local recurrences (23%) were more frequent than following conventional resections. On the other hand, the survival, 80% at one year, 62% at 2 years, 54% at 3 years and 39% at 5 years, related more to metastatic dissemination than to local recurrence, was comparable to that of the control group of pneumonectomised patients. This procedure gave identical results in terms of survival, but should be reserved for patients with respiratory failure due to the increased risk of local recurrence.

Adult↗
PubMed1992

[Forgotten mediastinal goiter: seven cases].

The authors relate their experience with 7 cases of mediastinal goiter residual to a subtotal thyroidectomy for substernal goiter. The differential diagnosis with ordinary recurrence was based on the absence of connection with the cervical remnant. The reasons for surgical decision-making was mediastinal compression in 4 patients, hyperthyroidism in 1 patient and absent diagnosis in 1 patient; surgery was systematic in 1 asymptomatic patient. Sternal splitting incision was required in 6 patients: alone in 3, associated with cervical incision in 3 others; excision by an exclusively cervical route was possible in one patient. No malignancy was discovered. Postoperative outcome was uncomplicated in all patients. The residual goiter has the same clinical and paraclinical presentation as the ordinary intrathoracic goiter; treatment should be principally surgical for the same reasons. Nevertheless, for this mediastinal tumor, sternum-splitting incision will be required in most cases.

Aged↗
PubMed1991

Expression of collagenase-related metalloproteinase genes in human lung or head and neck tumours.

We address the question as to whether increased metalloproteinase production might be related to the high regional recurrence rate of some carcinomas, and particularly head and neck squamous-cell carcinomas (SCC). Northern blot of total RNA prepared from 26 lung carcinomas, 107 head and neck carcinoma samples and corresponding normal tissue samples demonstrates the frequent and sometimes concomitant over-expression of the 2 stromelysin genes, the type-I collagenase gene and the pump-I gene in the head and neck tumour tissue samples. In these SCC, over-expression of the 2 stromelysin genes and the type-I collagenase gene (but not the pump-I gene) is associated with a high degree of tumour differentiation. Moreover, a tumour with high levels of the stromelysin mRNAs is more likely to show high local invasiveness, suggesting that the stromelysins may be implicated in the clinical course of head and neck tumours. Evaluation of the corresponding mRNA levels may prove a useful indicator for predicting the clinical aggressiveness of these tumours.

Biomarkers, Tumor↗
PubMed1991

Poly(diethyl methylidenemalonate) nanoparticles as a potential drug carrier: preparation, distribution and elimination after intravenous and peroral administration to mice.

Polymerization of diethyl methylidenemalonate (DEMM, 1a) in 0.1 M phosphate buffer containing 1% dextran 70 yields nanoparticles of a diameter ranging from 140 to 250 nm depending on the pH value (6.7 to 8.7). The weight-average and number-average molecular weight of the resulting polymer were 3791 and 1084, respectively. Approximately 95% of the 14C-labeled poly(DEMM) nanoparticles were found in liver and spleen 1 h after iv administration. A statistically significant (p less than 0.01) approximately 10% decrease of the radioactivity was observed in the liver over a 3-month period. The poly(DEMM) nanoparticles were not absorbed and were totally cleared from the gastrointestinal tract 24 h after oral dosage. The very slow bioelimination process observed after iv administration limits the usefulness of poly(DEMM) nanoparticles as a systemic drug carrier. Nevertheless, their oral administration as bioavailability enhancers can be envisaged. Moreover, the fact that nanoparticles are readily produced in a medium near neutrality should be emphasized.

Administration, Oral↗
PubMed1991

Synthesis of 1,3-diacylaminopropan-2-ols and corresponding 2-acyl derivatives as amide isosteres of natural lipids.

N,N'-diacyl-1,3-diaminopropan-2-ols as amide isosteres of 1,3-diacylglycerols are obtained in 50-79% yields by treatment of 1,3-diaminopropan-2-ol with acid chlorides either in ether or THF in the presence of triethylamine and catalytic amounts of 4-dimethyl-aminopyridine. Subsequent acylation of the secondary alcohol function with a variety of carboxylic acids (e.g. fatty acids, N-protected amino acids, drug compounds) can be effected by various techniques (i.e. acid chlorides, symmetrical anhydrides, isopropenyl chloroformate) with yields ranging from 56% to 76%.

Acylation↗
PubMed1991

Emergency repair of main stem bronchus disruption complicated by anastomotic stenosis: two cases of successful repair by resection and reanastomosis.

The case reports of two patients who developed complete bronchial stenosis after emergency repair of a left stem bronchus disruption are reported. Resection of the stenotic bronchus and reanastomosis restored a normal lung function in both patients. Arguments for a conservative approach, perioperative investigations, and technical data are discussed.

Accidents, Traffic↗
PubMed1991

Glossina fusca group tsetse as vectors of cattle trypanosomiasis in Gabon and Zaire.

1. The significance of Glossina fusca group tsetse flies as vectors of cattle trypanosomiasis was examined using biconical traps to survey tsetse populations at one site in Gabon and two sites in Zaire. 2. Mean trypanosome infection rates in G.tabaniformis Westwood over the study period ranged from a minimum of 8.9% at one site to a maximum of 17.7% at another. The mean infection rate in G.nashi Potts was 6.0%. 3. Up to 49% of bloodmeals of G.tabaniformis were from cattle. Trypanosome prevalence in cattle where G.tabaniformis appeared to be the main vector was 9.5% and 5.4% at the Mushie and OGAPROV ranches, respectively. 4. A highly significant positive correlation was found between tsetse challenge and trypanosome prevalence in N'Dama cattle across sites. Tsetse challenge was defined as the product of tsetse relative densities, trypanosome infection rates in the flies and the proportion of feeds taken by them from cattle. Thus, G.tabaniformis can be an important vector of pathogenic Trypanosoma species in cattle.

Animals↗
PubMed1991

[Non-aplastic N2 operated bronchial cancers. Multifactorial analysis of the prognosis].

The marked disparity of the published 5-year survival rates (0 to 3%) for non-anaplastic, operated N2 lung cancers would suggest the marked heterogeneity of the patients studied. We prospectively studies 97 N2 tumours for which "curative" resection was performed between 1983 and 1986. The overall survival rate was 28% at 3 years, 19% at 4 years and 12% at 5 years. Survival was studied on the basis of several parameters concerning the tumour: histological type and degree of differentiation, T (TNM), modality of invasion (circumscribed, infiltrating), the quality of the stroma (absent, fibrotic, cellular), the mitotic index, the necrosis rate, presence or absence of microscopic invasion of blood vessels; and concerning the nodes: site, number (solitary, multiple), size of the metastasis (massive, microscopic), macroscopic or microscopic invasion of the capsule. We know the outcome for all of our patients: 81 have died and 16 are still alive. Sixty-one have developed metastases, 5 have developed local and regional recurrences and 3 have both a recurrence and metastases. Univariate analysis demonstrated that a small number of parameters significantly influence survival: microscopic invasion of blood vessel (chi 2 = 5.24, p less than 0.02), macroscopic and microscopic invasion of the lymph node capsule. In order to more clearly define the prognostic factors, we used Cox's multidimensional model. This model was applied to the three significant parameters to which we added two other variables which non-significantly tended to be related to survival: tumour necrosis and number of lymph nodes involved.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1991

[The risks of surgical training. A study apropos of 348 pneumonectomies].

On the basis of the retrospective study of a series of 348 pneumonectomies, the authors have attempted to assess whether the risks of postoperative complications were increased if the operation was carried out by trainee surgeons. All operations were performed for cancer, with a stapler being used for bronchial suture. The patients were classified in three groups according to the surgeon: 133 (38%) were operated by an University professor (group I, 2 surgeons), 171 (49%) by chief resident or hospital practitioner (group II, 3 surgeons) and 44 (13%) by an intern (group III, 14 surgeons). The homogeneity of the 3 groups was checked with alpha X2 test. The study dealt with the overall mortality as well as with the specific complications of pneumonia, namely empyema and bronchopleural fistulae. The overall postoperative mortality rate was similar in the 3 groups (respectively 8%, 8% and 5%), as well as the occurrence of empyema (respectively 4%, 3% and 5%). A difference that, though not significant statistically, is not negligible, appears for bronchopleural fistulae, which complicate 9% of the operations carried out by interns vs. 4% in the other 2 categories. These observations challenge a number of studies claiming that surgery performed by inexperienced surgeons is innocuous. However, pneumonectomy is an essential step in the training to thoracic surgery, so that no candidate with sufficient surgical maturity should be prevented from performing it.

Female↗
PubMed1990

Vidarabine-loaded nanoparticles: a physicochemical study.

The chemical reaction of vidarabine (VIDA) with isohexyl cyanoacrylate nanoparticles in a pH-dependent fashion occurs only in the presence of dioctylsulfosuccinate (DOSS). The formation of an ion pair with DOSS allows a better contact of VIDA with the monomer during the polymerization process taking place in micelles. On the basis of molecular weight profiles of the polymer, determined by gel permeation chromatography (GPC), it is proposed that VIDA induces the polymerization of cyanoacrylic monomers through a zwitterionic pathway. This mechanism allows the covalent linkage of the drug with the polymer, which is consistent with NMR experiments. The present study illustrates the need for physicochemical studies in the design of new colloidal drug delivery formulations.

Chemical Phenomena↗
PubMed1990

[Perfusion scintigraphy and surgical excision of bronchial cancers].

In a series of 1,800 operated lung cancers, 93 had a unilateral perfusion scan less than or equal to 20% (36 perfusions = 0, 15 between one and 10% and 42 between 11 and 20%). Major amputations were more frequent on the left side and constituted a pejorative but non-decisive factor for surgical nonintervention although was not synonymous with inoperability. The extent of the resection increased with the severity of the amputation.

Carcinoma, Bronchogenic↗
PubMed1990

[Outcome of 100 necessary exploratory thoracotomies for bronchial cancer].

The outcome of one hundred exploratory thoracotomies for lung cancer (9.1% of operations) was studied. There were 4 postoperative deaths. After the operation, 6 patients did not receive any further treatment, 62 received radiotherapy, 25 received a combination of radiotherapy and chemotherapy and 3 received chemotherapy. The disease-free interval was very short with development of metastases (55 cases) and local recurrences (29 cases). The survival was also short: less than 10% at 2 years; it was significantly poorer than that observed in a group of non-operated patients with an equivalent stage of lung cancer. These findings suggest the need for stricter evaluation of operative indications.

Aged↗