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Biomedical subjects

A Franco

Publications and source records attributed to A Franco.

At least 199 records · Page 11Linked to original sources
PubMed1993

Two light attenuation models for automatic diameter measurement of the blood vessels.

The Lambert-Beer's law of the absorption of the light by blood in a vessel is used to model the light attenuation by a blood vessel that is transilluminated. Two models are used for an automatic vessel diameter determination for intravital microscopy. Some requirements for the photometric system have to be met in order to reduce errors due to light scattering. In these conditions, a videodensitometric pattern of the cross-section of the vessel can be fitted by the different models in order to obtain the diameter of the vessel. The first model proposed uses a uniformly distributed red blood cell column. A non-linear estimation of the diameter is done with the Levenberg-Marquardt method in 2 sec, using a regular PC386 microcomputer. The second one takes in account the presence of a plasma layer and computes the diameter of the red blood cell column and the diameter of the vessel in one minute. These models can be used for pharmacological studies or for a better understanding of the formation of a transilluminated intravital image. They can also be used for angiographic images.

Algorithms↗
PubMed1993

[The management of diarrheal disease at home in some regions of Mexico].

A survey was carried out between May and October, 1991 in eleven federal entities to know the correct household diarrhea case management (EMECADI). It was observed that among the 15,125 children less than five years old the punctual prevalence was of 6.4% (970 children); the incidence in the previous two weeks was 14.5% (1,605 children) and the annual incidence of diarrhea was 4.5 episodes per child per year. Among the children who presented diarrhea in the 24 hours, the following rates were observed: use of oral hydration solution, 17.1%; use of recommended homemade fluids, 63.2%; oral hydration therapy use, 63.2%; increased fluids, 29.9%; correct oral serum preparation, 60.0%; continued breast-feeding, 75.0%; continued feeding, 59.8%; adequate knowledge about seeking care, 12.5%, and drugs use, 53.2%. The reference and nutritional components should improved.

Breast Feeding↗
PubMed1992

Transferrin receptor mediates uptake and presentation of hepatitis B envelope antigen by T lymphocytes.

Human activated T lymphocytes expressing class II molecules are able to present only complex antigens that bind to their own surface receptors, and thus can be captured, internalized, and processed through the class II major histocompatibility complex processing pathway. We have used the antigen-presenting T cell system to identify the viral receptor used by hepatitis B virus (HBV) to enter cells, as well as the sequence of HB envelope antigen (HBenvAg) involved in this interaction. Results show that both CD4+ and CD8+ T clones can process and present HBenvAg to class II-restricted cytotoxic T lymphocytes and that the CD71 transferrin receptor (TfR) is involved in efficient HBenvAg uptake by T cells. Moreover, we provide evidence that the HBenvAg sequence interacting with the T cell surface is contained within the pre-S2 region. Since TfR is also expressed on hepatocytes, it might represent a portal of cellular entry for HBV infection. This system of antigen presentation by T cells may serve as a model to study both lymphocyte receptors used by lymphocytotropic viruses and viral proteins critical to bind them.

Amino Acid Sequence↗
PubMed1992

Tumor necrosis factor-alpha and interferon-gamma synthesis by cerebrospinal fluid-derived T cell clones in multiple sclerosis.

T cell clones derived from cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS) were analysed for their capacity to produce interleukin 2 (IL-2), interleukin 4 (IL-4), interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha). They were also compared with liver-infiltrating T cell clones from patients with chronic active hepatitis. All the CSF T clones (both CD4+ and CD8+) produced large amounts of IFN-gamma and particularly of TNF-alpha, that was synthesized in a significantly larger amount than compared clones. Moreover, they were capable of secreting IL-2, but not IL-4. From our results, we conclude that first, the CSF CD4+ T clones could constitute a subset with functional properties similar to the T helper 1 (Th1)/inflammatory cell subset of the mouse; and second, the large amounts of TNF produced by CSF T cell clones strongly suggests a significant role for this cytokine as well as of IFN-gamma in MS immunopathogenesis.

Adult↗
PubMed1992

T cell recognition of hepatitis B envelope proteins.

We have studied the T-cell processing pathways of Hepatitis B antigens and the role of specific B lymphocytes. It could be shown that some form of processing by specific B cells is required for class I CTLs. This mechanism differs from class II endosomal processing. In addition, it could be shown that lysis of HBsAg-specific B cells may be partly responsible for chronic HBV carrier states.

B-Lymphocytes↗
PubMed1992

Further consideration of the clonal nature of Salmonella typhi: evaluation of molecular and clinical characteristics of strains from Indonesia and Peru.

We examined envelope protein profiles, chromosomal restriction endonuclease digest patterns, and immune responses to envelope proteins for collections of Salmonella typhi strains isolated in Peru and Indonesia. Only minor differences in envelope protein patterns were apparent among strains. Strains from 7 of 20 Indonesian patients had a distinct chromosomal digest pattern compared with patterns of Peruvian and other Indonesian strains. Strains with this pattern carried the gene for the j flagellar antigen (H1-j); differences in response to envelope proteins of j and d strains were noted on immunoblot analysis. Our data suggest that there are genotypic and phenotypic differences among S. typhi strains. The clinical importance of these differences remains to be fully evaluated; however, in this study it was not possible to show a clear correlation between strain characteristics and disease severity.

Bacterial Proteins↗
PubMed1992

Comparative study between the use of a treatment with hyperthermia through the rectal approach versus the urethral approach for benign prostatic hyperplasia.

200 patients suffering from benign prostatic hyperplasia were treated with hyperthermia: 100 cases through the rectal approach and 100 through the urethral approach. Subjective symptoms were assessed as well as nycturia and objective data, urinary flow and postmicturition residue before treatment and 6 months after treatment. In the group of 100 patients treated rectally, the subjective symptoms and nycturia improved in 76; urine flow improved in 63, postmicturition residue decreased in 32 and the vesical catheter could be removed in 5 out of 8 patients. With the urethral approach, 77 patients out of 100 presented an improvement in their symptoms, nycturia improved in 53; urine flow improved in 28; the urine residue was decreased in 40 and the vesical catheter could be removed in 10 out of 16 patients who required it previously. Although slightly better results seem to be achieved with the use of rectal hyperthermia, as concerns nycturia and micturition flow, we prefer the urethral approach for its higher degree of convenience, easier handling, shorter time of treatment and reasonable effectiveness.

Aged↗
PubMed1992

Plasmids in Salmonella typhi in Lima, Peru, 1987-1988: epidemiology and lack of association with severity of illness or clinical complications.

A prospective study was conducted to better characterize the epidemiology of plasmid-bearing strains of Salmonella typhi in an endemic area of Lima, Peru, and to determine if plasmids were associated with specific manifestations of typhoid fever. Of 228 S. typhi isolated from patients at Cayetano Heredia University Hospital in Lima during 1987-1988, 76 (33%) contained plasmids. Ten different plasmid profiles were identified, with ten distinct plasmids present within these profiles. There was significant temporal clustering of isolates having common plasmid profiles. Two plasmids (both from the same isolate) carried antibiotic resistance genes. Two cryptic plasmids with approximate sizes of 55 and 65 kilobases (kb) appeared to be closely related, based on restriction endonuclease digestions and Southern blot analysis. An ampicillin resistance plasmid from a 1989 patient isolate differed by only a single restriction fragment from the cryptic 65-kb plasmid. No association was found between any plasmid or plasmid profile and severity or clinical manifestations of disease.

Blotting, Southern↗
PubMed1992

Evolution of lipid profiles in long-term peritoneal dialysis.

Serial lipid profiles of 102 patients starting chronic ambulatory peritoneal dialysis (CAPD) in our renal unit from January 1985 to December 1990 were collected retrospectively. Transient triglyceride elevation was noted during the first two years of CAPD but declined to normal levels even lower than those at baseline by 60 months. Total cholesterol, HDL and LDL cholesterol levels did not change significantly. Lipid-lowering agents were begun in 17 patients before initiating CAPD, 5 of whom achieved lipid profiles warranting cessation of therapy. Five other patients started treatment while on CAPD. No statistical difference in patient mortality was found when patients hyperlipidemic at the initiation of CAPD were compared to their normolipemic counterparts. We conclude that the return to normal plasma triglyceride levels after transient triglyceride elevation during long-term CAPD implies that adaptative mechanisms of triglyceride production in response to chronic glucose overload may ensue.

Adolescent↗
PubMed1992

[Use of an active clinical maneuver for diagnosis of popliteal artery entrapment].

Overall incidence rate of popliteal artery entrapment syndrome is certainly underestimated. The aim of this work was to test and to evaluate the interest of a clinical maneuver of active and repetitive ankle extensions in upright position, for the screening, the diagnosis and the follow-up of patients with popliteal artery entrapment. During a 3 year period, this maneuver was used in 10 patients (16 popliteal artery entrapments) and in 50 age-matched controls. The results of the maneuver were compared to the results of functional vascular investigations. For all the patients the maneuver had to be stopped before 20 movements whereas it could be continued up to 50 movements for all the controls. The maneuver was easy to perform, reliable and constant in its results. The earlier the maneuver was stopped the more critical was the trouble at functional vascular investigations. We believe that this maneuver is of great help for early diagnosis of popliteal artery entrapment, assessment of its severity and follow-up treated patients. It could also help to detect athletes with asymptomatic popliteal entrapment.

Adolescent↗