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Biomedical subjects

C Alvarez

Publications and source records attributed to C Alvarez.

293 records · Page 17Linked to original sources
PubMedDate not supplied

Etiologic study of stroke in 95 young adults.

The aim of this prospective study was to determine the etiologic factors leading to stroke in a group of young adults. We studied 95 patients aged 50 years or under who were admitted with the diagnosis of stroke over a 2-year period. These patients underwent complete clinical and laboratory assessment for stroke. The etiology was established in 73 (76.8%) out of 95 cases. Arterial hypertension, embolism and atherosclerosis were found to be the most frequent causes in patients with ischemic stroke, whereas hypertension and aneurysm rupture were the most prevailing etiologies in patients with hemorrhagic stroke. Miscellaneous causes represented one fourth of all cases of the series. Coagulation abnormalities occurred in some patients, but in these cases there were also other well established causes. Paradoxical embolism was not observed. This study corroborates the importance of thorough diagnostic evaluation to establish an accurate diagnosis.

Adult↗
PubMedDate not supplied

Expression of mannose-binding sites on human spermatozoa and their role in sperm-zona pellucida binding.

A D-mannosylated albumin (DMA) neoglycoprotein was assessed to validate experimentally a probe capable of detecting mannose-binding sperm receptors involved in human sperm-egg interaction. DMA specifically blocked zona binding of swim-up human spermatozoa in a concentration-dependent manner. While no considerable effect was observed on sperm-zona initial contact, almost 50% of spermatozoa bound to the zona during a 2-hour period detached from it when DMA was introduced in the incubation medium. DNA inhibition was evident when 10% fetal bovine serum, but not 3.5% human serum albumin (HSA), was used as Ham's F10 medium supplementation. This may be due to the amount of free calcium in the medium since addition of 40 mM CaCl2 to F10-HSA restored DMA inhibition. Furthermore, the higher the calcium concentration in the incubation buffer, the greater the DMA blockage of sperm-zona binding. Unfixed sperm presented fluorescent DMA label over the entire acrosomal area (cap pattern), or concentrated at the equatorial segment (bar pattern). These patterns increased during capacitation, appearing on an average of 20% of the sperm after overnight incubation. They also increased, especially the bar pattern, following calcium ionophore treatment. Nearly all of methanol-fixed spermatozoa displayed the fluorescent label at the head level. Concomitant assessment of sperm membrane integrity and DMA fluorescent patterns revealed that DMA fluorescence coincided mostly with permeabilized or altered sperm plasma membrane. In conclusion, DMA is a suitable probe to identify human sperm mannose-binding sites crucially involved in sperm-zona interaction. These sites appear to require free calcium concentrations to operate, and their expression changes with capacitation and acrosome reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrosome↗
PubMedDate not supplied

[Primary Sjogren syndrome with involvement of the nervous system. Description of 4 cases].

Four patients, 2 males and 2 females, with primary Sjögren's syndrome (PSS) and neurologic involvement are described. The first patient presented a progressive axonal polyneuropathy due to endo-epineural vasculitis. The second patient developed an acute and focal lymphocytic meningoencephalitis with increased IgG synthesis and excellent response to corticosteroids. The remaining 2 patients had previously been diagnosed as having definite multiple sclerosis (MS), but after a standardized study both fulfilled PSS diagnostic criteria. These cases illustrate the polymorphism of the neurological manifestations in PSS. Pathogenetic relationships between PSS and MS are briefly reviewed.

Adolescent↗
PubMedDate not supplied

[Evaluation of reticulocyte count on Cell-Dyn 3500 automate: comparison with a flow cytometry technique].

Cell-Dyn 3500 automate (Abbott) provides reticulocyte count using a recent software, after ribosomal RNA colouring with methylene blue reagent. The aim of this study was to evaluate results from Cell-Dyn 3500, and to compare them with the routine laboratory technique by flow cytometry (FacScan, Becton-Dickinson). Cell-Dyn 3500 analytical parameters (inter- and intra-assay precision, sample-to-sample contamination) were good and in accord to manufacturer's specifications. Reticulocyte values from blood samples kept at 4 degrees C during 3 days were unchanged. Usual values in 145 normal patients were found between 71.3 and 78.3 G/l with Cell-Dyn 3500, between 119.3 and 130.2 G/l with FacScan. Both techniques were compared in 87 patients with various anemias: Cell-Dyn 3500 showed more frequently high reticulocyte values in regenerative anemias (hemorrhagic), but was less performant for classification of aregenerative anemias. Reticulocyte count with Cell-Dyn 3500 is a semi automatic, easy to perform and swift technique, using no toxic reagent but unitary test tubes kept at room temperature. The test cost is however high, and Cell-Dyn 3500 cannot be used during the analysis.

Flow Cytometry↗