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Biomedical subjects

A Haddad

Publications and source records attributed to A Haddad.

At least 37 records · Page 2Linked to original sources
PubMed2000

Increasing drug resistance of Mycobacterium tuberculosis isolates in Ontario, Canada, 1987-1998.

We examined trends in resistance to first-line antituberculous agents for Mycobacterium tuberculosis strains isolated in Ontario, Canada from 1987 through 1998 (n=8069). The proportions resistant were as follows: isoniazid, 9.6%; rifampin, 1.9%; streptomycin, 4. 9%; ethambutol, 1.3%; and pyrazinamide, 1.7%. Resistance to isoniazid has increased markedly since 1990, whereas resistance to streptomycin, ethambutol, and pyrazinamide increased from 1997 through 1998. Resistance to both isoniazid and rifampin did not increase. The incidence of persistence and reactivation (early or late treatment failure) was 1-2 per 100 person-years (PY) in the first 7-12 months and 0.3-0.9 per 100 PY from 13 months to 5 years thereafter. For initially susceptible strains, the incidence of resistance to isoniazid was 0.11 per 100 PY and for and rifampin was 0.06 per 100 PY in the first year and negligible thereafter, with an overall risk of 0.14% for isoniazid and 0.10% for rifampin. Resistance of M. tuberculosis to antituberculous agents, and in particular to isoniazid, is a growing problem in Ontario and is higher than elsewhere in Canada.

Antitubercular Agents↗
PubMed2000

Thermally affected characterization region by Barkhausen noise.

The controlling of some industrial components require the development of new and particular nondestructive testing techniques. The testing method using Barkhausen noise (BN) is a particular one which can be applied to ferromagnetic materials. It is a magnetic nondestructive evaluation method and can provide very important information about the material structure. The aim of our work is to study the material structure using this technique to characterize the region submitted to thermal processing. Samples of steel have been heated at temperatures between 650 degrees C and 1,200 degrees C with variable parameters (time processing, maintenance time, etc.). Acoustic BN processing allows an easy interpretation of results. Micrographs of samples have been obtained to confirm the results obtained by BN.

Fourier Analysis↗
PubMed2000

Renewal of the rabbit corneal epithelium as investigated by autoradiography after intravitreal injection of 3H-thymidine.

PURPOSE: To evaluate the renewal time of the rabbit corneal epithelium and to verify whether there are differences in the rate of renewal related to the topography of the cornea. METHODS: After the intravitreal injection of 20 microBq/eye of 3H-thymidine (3H-TdR), the rabbits were killed at variable survival-time intervals (3 hours to 90 days), and their corneas were processed for autoradiography on paraffin and 0.75-microm-thick Epon sections. The frequency of labeled nuclei, per each linear millimeter of epithelium, was estimated on paraffin sections of the whole length of the cornea of rabbits killed 6 hours after injection. The activity of unbound 3H-TdR was measured in the vitreous and aqueous humor. RESULTS: The incorporation of 3H-TdR into newly synthesized DNA ceased between 1 and 2 days after the intravitreal injection. At the shortest time intervals (3 hours to 1 day), the overwhelming majority of the labeled nuclei were located in the basal stratum of the stratified squamous epithelium. Cells of the wing stratum were labeled from 3 days onward. At 14 days, labeled nuclei were visualized only in the inner portion of the surface stratum, whereas their outermost layers were labeled only at 21 days and later. Lightly labeled nuclei could still be detected in the epithelium < or = 90 days after injection. The counts of labeled nuclei did not show significant differences in their frequencies between the periphery and the center of the cornea. The existence of vascularization at the periphery of the corneal stroma and the lack of a conspicuous Bowman's layer made it difficult to characterize morphologically the rabbit limbus with the light microscope. CONCLUSION: It takes >14 days for a daughter cell to migrate from the basal stratum to the outermost layer of the epithelium. Labeled daughter cells were detected < or = 90 days in several layers of the corneal epithelium. Therefore it takes >2 weeks for the complete renewal of the epithelium. Our data suggest that the proliferative capability of the centrally located basal cells is enough to guarantee the renewal of the corneal epithelium under physiologic conditions.

Animals↗
PubMed2000

[Parathyroid carcinoma: diagnosis and treatment].

Pre operative and per-operative suspicion, and recognition of parathyroid carcinoma are essential in the effective approach and the prognosis of this type of tumor. On the basis of our experience over 20 years, helped by the literature we review our 179 cases of primary hyperparathyroidism out of which 5 were malignant tumors and the 174 others were benign (adenomas and hyperplasias). We conclude that patients with primary hyperparathyroidism, reflected by high levels of serum calcium (75%) and elevated levels of parathormone (100%) are suspect of carrying a parathyroid malignancy particularly when these levels are profoundly abnormal. Furthermore, a severe clinical presentation featuring, palpable cervical mass, renal symptoms in 30% to 60% of all, bone disease in 90%, is suspect of malignancy. The operative findings such as important size of tumour, local seeding, local invasion are also significant features of malignancy. All this data gathered by comparing carcinomas to adenomas suggest and confirm what many reviews on the subject have reported, early recognition of the parathyroid carcinoma is of primal importance, because aggressive initial surgical management should be applied, as total extirpation of the malignancy is the only treatment allowing maximal survival rates.

Aged↗
PubMed2000

[Predictive malignancy factors in thyroid nodular disease].

Nodular thyroid pathology is frequent and remains a controversial issue when it comes to establishing an ideal endocrine surgical strategy. We studied clinical and complementary data predictive of malignancy using a large retrospective analysis of 366 cases operated for nodular pathology of the thyroid gland between January 1995 and December 1997 in our Head and Neck Surgery Unit of the Pasteur Hospital in Nice, France. The incidence of malignancy was 12.8% with the usual histologic findings (83% of well-differentiated tumors: 70% papillary, 13% vesicular, 9% medullar, 6% oncocytic and 2% anaplastic). Statistical analysis did not conclude on the predictive value of several items in terms of their relationship to high risk of malignancy (p > 0.05): size of nodules, signs of local compression, biological findings, presence of calcifications, mixed ultrasound aspect, no hypoechogenic halo, scintigraphic aspect. This retrospective work did however identify items predictive of malignancy when appearing in patients with nodular thyroid disease: male sex (odds ratio 2.4; 95%CI [1.17-4.88]; p=0.13), age (less than 40 yr or more than 70yr) (p=0.003), hard nodule consistency (odds ratio 7.40; 95%CI [3.99-13.52], p<0.001), invasion of lymphatic nodes noted prior to surgery (p=0.031), hyperechogenicity on ultrasound exam (p=0.013). We were able to confirm the highly negative predictive value (92%) of fine needle aspiration, emphasizing its value in endocrine thyroid nodular disease diagnosis.

Adolescent↗
PubMed1999

Glycosaminoglycans in components of the rabbit eye: synthesis and characterization.

PURPOSE: To trace the eye components involved in proteoglycan synthesis and to characterize the sulfated glycosaminoglycans which are associated to these macromolecules. METHODS: Sodium [(35)S]-sulfate was injected intravitreally and the rabbits were killed at different time intervals after the injection. The glycosaminoglycans of choroid, ciliary body, cornea, iris, lens capsule, retina and sclera were extracted and processed for estimations of their specific activities, and for electrophoresis plus autoradiography with or without previous treatment with specific enzymes. In addition, methacrylate sections of the eyes were analysed by autoradiography. RESULTS: The peak of specific activities of the glycosaminoglycans of all eye components occurred at 2 days after the intravitreal injection of [( 35)S]-sulfate. The autoradiography of the agarose gels revealed three types of glycosaminoglycans, namely, heparan-, chondroitin- and dermatan sulfate, only in the retina. The other eye components contained heparan sulfate and either chondroitin or dermatan sulfate. Tissue autoradiography together with the biochemical techniques contributed to unravel the origin of the glycosaminoglycans in the eye components. CONCLUSIONS: The results of the present investigation have shown that heparan sulfate, contrasting to chondroitin sulfate and dermatan sulfate, is synthesized in all eye components studied and that the glycosaminoglycan composition differs according to the tissue of origin.

Animals↗
PubMed1999

Nasal endoscopic repair of cerebrospinal fluid rhinorrhea.

The surgical management of Cerebro-spinal Fluid (CSF) rhinorrhea has been modified these last years due to the improvement of endoscopic sinus surgery techniques allowing the treatment of selective dural tears by the endonasal route. Over a period of 6 years, 27 patients with CSF rhinorrhea were operated on by the endonasal approach under optical guidance. CSF rhinorrhea was due, in 20 cases, to surgical iatrogenic trauma, in 4 cases to head injury, and in 1 case it was secondary to a conservative medical treatment of a pituitary adenoma. In 2 cases the cause was unknown. The average follow-up in this series was 24.7 months. The technique used was successful in 22 patients (81.5%). Considering these results and others reported in the literature, we think the use of the endonasal approach with optical guidance should always be considered as a valuable alternative to open surgery and should be discussed in all cases of CSF rhinorrhea with neurosurgeons.

Adult↗
PubMed1999

[Chronic sinusitis in patients infected by HIV: therapeutic strategies].

Chronic sinus pathology is a frequently encountered disease in HIV infected patients. The responsible bacterial agents and management are yet to be settled. The authors report the results of a retrospective study led in the unit of Head and Neck Surgery of the University Hospital of Nice. 25 patients where HIV holders and had a sinus pathology which had lasted more than 6 weeks, despite one or several antimicrobial drug administrations. Clinical and CT scan data are detailed as well as pathology results of the samples harvested during sinus surgery (bacteria free 32%, Pseudomonas aeruginosa 32%, Streptococcus pneumoniae 16%, Staphylococcus aureus 16%, Hemophilus influenzae 16%, anaerobic agents 16% and Toxoplasma gondii 4%). All patients underwent surgery (antral puncture with maxillary sinus drainage 17, functional endoscopic sinus surgery 8). Results where gathered at 4 months with 76% of relapse (100% in patients with less than 200/mm3 CD4 cells). In conclusion empiric antimicrobial drug therapy will be expected to be also effective on Pseudomonas aeruginosa, the surgical management being most often deceiving and leading to relapse especially when considering the frequency of bilateral morbidity and the level of CD4 cell below 200/mm3.

Adult↗