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Biomedical subjects

A Haddad

Publications and source records attributed to A Haddad.

At least 91 records · Page 5Linked to original sources
PubMed1995

[Spinal cord compression in bone fluorosis. Apropos of 4 cases].

The authors report four cases of spinal cord compression (three at cervical level and one at dorsal level) due to vertebral osteosclerosis secondary to chronic fluoride intoxication. Roentgenograms showed typical diffuse densification of vertebral bodies, calcifications of bony insertions of many ligaments, discs and interosseous membranes. Urinary fluoride was markedly increased in two cases. In the other two cases the bone biopsy was suggestive of skeletal fluorosis. Spinal computed tomography showed severe cord compression due to posterior osteophytes. Good improvement was observed after surgical decompression in one case. Fluorosis was described as a consequence of endemic exposure to high fluoride content in soil and natural ground water in North Africa. Fluorotic myelopathy was due to bone excrescences mainly affecting the spine.

Bone Diseases↗
PubMed1995

Phylogenetic characterization of the epibiotic bacteria associated with the hydrothermal vent polychaete Alvinella pompejana.

Alvinella pompejana is a polychaetous annelid that inhabits active deep-sea hydrothermal vent sites along the East Pacific Rise, where it colonizes the walls of actively venting high-temperature chimneys. An abundant, morphologically diverse epibiotic microflora is associated with the worm's dorsal integument, with a highly integrated filamentous morphotype clearly dominating the microbial biomass. It has been suggested that this bacterial population participates in either the nutrition of the worm or in detoxification of the worm's immediate environment. The primary goal of this study was to phylogenetically characterize selected epibionts through the analysis of 16S rRNA gene sequences. Nucleic acids were extracted from bacteria collected from the dorsal surface of A. pompejana. 16S rRNA genes were amplified with universal bacterial primers by the PCR. These genes were subsequently cloned, and the resulting clone library was screened by restriction fragment length polymorphism analysis to identify distinct clone types. The restriction fragment length polymorphism analysis identified 32 different clone families in the library. Four of these families were clearly dominant, representing more than 65% of the library. Representatives from the four most abundant clone families were chosen for complete 16S rRNA gene sequencing and phylogenetic analysis. These gene sequences were analyzed by a variety of phylogenetic inference methods and found to be related to the newly established epsilon subdivision of the division Proteobacteria. Secondary structural model comparisons and comparisons of established signature base positions in the 16S rRNA confirmed the placement of the Alvinella clones in the epsilon subdivision of the Proteobacteria.

Animals↗
PubMed1995

Adenoid cystic carcinoma of the head and neck: a clinicopathologic study of 37 cases.

The records of 37 patients with histopathologically confirmed adenoid cystic carcinoma, who presented to McGill University's Department of Otolaryngology between 1956 and 1990, were reviewed to determine factors influencing local failure, distant metastases, and survival. Of the 37 cases, 12 developed local recurrences. Local failure was seen an average of 3.5 years following initial treatment, 62% of which were seen prior to 2 years. No statistically significant advantage was found for the use of postoperative radiotherapy in the prevention of local recurrences. Thirteen cases presented with or subsequently developed distant metastases. The mean interval between initial treatment and the appearance of distant disease was 8.1 years. A comparison of survival in patients with negative versus positive surgical margins was carried out. Survival at 15 years with negative margins remained 100%, while with positive margins, only 35% survived. Disease-free survival with negative and positive margins at 10 years was 80% and 31.1%, respectively. The effect of positive margins on survival was statistically significant with a p values between .01 and .001. The aim of this study was to demonstrate the importance of negative surgical margins with regard to survival. The results suggest that negative margins at initial resection significantly improve long-term disease-free survival.

Actuarial Analysis↗
PubMed1994

Transferrin, one of the major vitreous proteins, is produced within the eye.

Transferrin occurs in the vitreous at a higher relative concentration than found in the plasma or in the aqueous humor. This has been related to a possible local synthesis of transferrin by some component of the eye, although convincing evidence for this has not been available. Recently, the intraocular synthesis of several vitreous glycoproteins, possibly by the ciliary body, was demonstrated by our group. This paper reports experiments that characterize vitreous transferrin as one of these glycoproteins. Vitreous of rabbits injected intravitreally either with 3H-fucose or 3H-tyrosine and killed 40 hr after the injection was processed for 1D and 2D-electrophoresis, followed by immunoblot techniques or fluorography. It was possible to detect a labeled polypeptide with the same molecular weight and pI of rabbit plasma transferrin. Furthermore, this labeled polypeptide could be specifically eluted from columns of Sepharose conjugated with antibody against rabbit plasma transferrin. Thus, these results demonstrate that at least part of the transferrin of the vitreous is synthesized within the eye.

Animals↗
PubMed1994

Serum albumin enters the posterior chamber of the eye permeating the blood-aqueous barrier.

In order to check the entrance site of serum albumin into the aqueous humor, rabbits were injected intravenously either with Evans blue (which reacts very quickly with albumin) or horseradish peroxidase. The Evans blue-albumin complex (Eb-a) was traced to the posterior chamber as early as 1 min after injection by examining frozen half eyes. The Eb-a was localized in frozen sections by fluorescence microscopy in the stroma of the ciliary and iridial processes, as well as in the lumen of all blood vessels from 1 to 60 min after injection even at doses as low as 3 mg/kg. The peroxidase activity was also localized on these same structures from 8 min to 4.5 h. Neither tracer was visualized in the iris stroma outside the lumen of blood vessels. This was also true for experiments with Eb (75 mg/kg) in which the blood-aqueous barrier was disrupted. The concentration (m/v) of Evans blue and the peroxidase activity in the aqueous humor of the anterior chamber were estimated by spectrophotometry. The morphological integrity of the blood-aqueous barrier was demonstrated by electron microscopy in all peroxidase-injected rabbits. Considering that (a) the Eb-a appeared first in the posterior chamber, (b) there was a high concentration of tracers in the stroma of the ciliary and iridial processes, (c) neither tracer was visualized in the iris stroma, (d) there was no evidence of disruption of the blood-aqueous barrier, and (e) the concentration of both tracers in the aqueous humor kept increasing up to 4 h after injection, it was assumed that serum macromolecules entered first the posterior chamber and subsequently migrated to the anterior chamber. Most likely they passed in between the cells of the inner layer of the ciliary epithelium, the site of the so-called blood-aqueous barrier. No evidence was found indicating migration of macromolecules from the stroma of the processes directly to the anterior chamber via the iris root.

Animals↗