Search

Introduction: A subpopulation of neoplastic cells with characteristics of stem cells has been described on human multiform glioblastomas. These cells play a pivotal role in tumour angiogenesis and malignancy being involved in infiltration of adjacent normal parenchyma. The named glial stem cells could be responsible for recurrences after surgery. This is due to their survival capacity after quimio/radiotherapy treatments., Development: In this work we review the role of glial stem cells in relationship with angiogenesis process. We also review some findings related to the appearance of these cells during angiogenesis in a rat endogenous experimental model of gliomas. These cells were characterized by antibodies against the antigens CD133, nestin and the vascular endothelial growth factor (VEGF). Nestin+ cells were found in every stage of tumour development, whereas CD133+ cells were only present since intermediates stages corresponding with VEGF overexpression. This moment is known as start of angiogenesis or 'angiogenic switch'. We also found that some nestin+ cells co-expressed CD133 antigen. Glial stem cells are distributed in the experimental glioma model as well as in human multiform glioblastomas, shaping niches into perivascular or intra-tumoral hypoxic areas., Conclusion: Many evidences corroborate the hypothesis that glial stem cells have a close relationship with angiogenic switch, intratumor hypoxia and neoplastic microvascular network.

Lipopolisaccharide (LPS), also called endotoxin, is the major component of the external membrane in Gram negative bacteria. This molecule is released to circulation by the bacteria, producing a large variety of toxic and pro-inflammatory effects which are associated with lipid A as well as with sepsis pathogenesis. Many physiological phenomena produced by LPS arise from this molecule's capacity to activate cells in the host immune system such as monocytes, macrophages and polymorphonuclear leukocytes. This process leads to a local inflammation, and it is beneficial for the host. However, if the amount of LPS released exceeds the critical concentration threshold an augmented release of inflammatory cytokines as TNF-alpha, and interleukines (IL) produce a severe sepsis. This fact led us to find therapeutical alternatives able to neutralize circulating endotoxin. This work is focused on the experimental results obtained in vivo and in vitro using synthetic proteins and peptides in order to neutralize LPS, and on future perpectives in this research area that offer the use of lipoprotein and in particular apolipoprotein A-I and mutants or peptides derived from this protein.

An increase in parathyroid hormone (PTH) levels in chronic renal failure (CRF) induces bone abnormalities known as renal osteodystrophy (ROD). The aim of the present study was to evaluate alternative biochemical methods to bone biopsy, to evaluate changes in bone remodeling in renal patients. Intact PTH (iPTH) and bone markers were measured in 43 predialysis (PD), 49 hemodialysis patients (HD) and 185 controls. betaCTXs, bone alkaline phosphatase (bAL), iPTH were higher and creatinine clearance (Ccr) was lower in PD and HD compared with controls (p < 0.0001). In both renal groups, a positive correlation was found between iPTH and both betaCTXs and bAL (p < 0.0001) and between betaCTXs and bAL (p < 0.002). PD patients with Ccr < 40 ml/min had higher iPTH, bAL and betaCTXs (p<0.004, p<0.05 and p<0.001, respectively) than patients with Ccr > 40 ml/min. betaCTXs (p < 0.05) in PD and betaCTXs and bAL in HD patients were higher than controls, even when iPTH was within normal range (< 65 pg/ml). Patients with severe secondary hyperparathyroidism showed higher bone markers than patients with normal or moderately increased iPTH (p < 0.001). These results suggest that even when there is no increase in iPTH, bone remodeling increases (possibly due to other factors) exhibiting higher bone resorption, and betaCTXs would seem to be an adequate non-invasive tool to assess early bone changes in CRF and prevent future fractures. Bone marker measurements in ROD would be useful to identify patients who may require bone biopsy. However, further studies comparing both methods must be performed before replacing bone biopsy with serum beta-CTX.

In order to evaluate clinical presentation and to determinate classification criteria of type 1 diabetes in the elderly, we carried out a study in 258 diabetic patients more than 60 years old of which 100 used insulin by failure to oral hypoglycemic agents (OHA). The prevalence of ischemic cardiovascular disease was 36%, peripheral vascular disease 34% and stroke 30%. Non-proliferative retinopathy 47%, nephropathy 16% and peripheral neuropathy 37%. Cardiovascular risk factors as obesity (36%), hypertension (33%) and hypercholesterolemia (12%) were evaluated. The average duration of diabetes was 20 years. Post-glucagon C-Peptide, HLA-DR antigens and islet cell antibodies (ICA), were measured in 75 older diabetic patients on treatment of which 24 used insulin, 11 diet and 40 OHA. Older patients on treatment with insulin had longer duration of disease, less obesity, low level basal of C-Peptide and a low response to post glucagon C-Peptide (0.94 +/- 0.5 pmol/ml) compared with patients on diet (1.8 +/- 0.9 pmol/ml) and OHA (1.8 +/- 0.8 pmol/ml). Older diabetics on insulin therapy had a greater frequency of HLA-DR3 (42%) and HLA-DR4 (21%) than other older diabetics. The ICA was negative in most patients. This study shows the high prevalence of macrovascular and microvascular disease in elderly patients with diabetes mellitus and that the most reliable parameter in classifying type 1 (insulin-dependent) diabetes is the measurement of basal and post-glucagon C-Peptide. HLA-DR specific markers can be used with this parameter because their expression is partly shared. This approach appears useful in the older diabetic patients to help classify diabetes and its management.

The kinetic of release of the tissular polypeptide antigen (TPA) by MCF-7 cells synchronised by sequential treatment with hydroxytamoxifen (OH-TAM) and 17 beta-estradiol has been studied. The present findings confirm the proliferative effect of estradiol on MCF-7 cells, with a shortening of the doubling time (TD) (22.2 h versus 24.8 h) and an increase in the growing fraction (Fc) (94% versus 81%) when compared with the same parameters measured in cells rescued from OH-TAM but not treated with estradiol. In addition, the action of estradiol was followed by a simultaneous increase in the amount of TPA in the culture medium related with the phases G2/M and G1 of the mitotic cycle. This phenomenon seems to be the reason for the steplike shape of the TPA released curves. The experimental results suggest that in MCF-7 cells the sequential combination of antiestrogenic agents and estrogens leads to a cellular synchronization. Furthermore this synchronization is maintained for at least 3 cycles of cell division.

In 20 type I diabetic patients treated with conventional insulin preparations, we measured insulin antibodies and peptide C secretion. Peptide C levels 90 and 120 min after a standard breakfast correlated well with glucosylated Hb levels (r = -0.48 and -0.52, respectively). No correlation with free insulin levels was observed, in spite of a good correlation of the latter with blood glucose levels (r = -0.50 and -0.73, respectively). There was no relation between insulin antibody levels and peptide C or free insulin. Metabolic control was not affected by insulin antibodies. Insulin dose decreased in relation to the duration of the disease and reduction of body weight index and was not correlated to glycosylated Hb levels.

Tissue and plasma concentration of peptide YY (PYY) were measured by means of a radioimmunoassay (RIA) developed in our laboratory, using a specific PYY antiserum generated in New Zealand white rabbits against synthetic PYY, and dextran-coated charcoal to terminate the assay. Cellular localization of PYY was studied immunohistochemically using the peroxidase-antiperoxidase (PAP) technique. The highest tissue concentration of PYY was found in the mucosa of the terminal ileum and colon. PYY-containing secretory granules were primarily found in the basal pole of open-type endocrine cells. Basal plasma concentration of PYY was 70 +/- 9 pg/ml and rose to 357 +/- 30 pg/ml during the IV administration of PYY at 400 pmol/kg-h. A significant correlation was found (r = 0.94, p less than 0.05) between dose of PYY (12.5, 25, 50, 100, 200, 400 pmol/kg-h, IV) and plasma concentration of PYY. The calculated half-life of PYY in plasma was 8.3 +/- 1.9 minutes. Plasma concentration of PYY during the intraduodenal administration of sodium oleate (150 +/- 20 pg/ml) or long-chain triglyceride (187 +/- 37 pg/ml) was similar to plasma concentration of PYY obtained during the IV administration of PYY at 100 pmol/kg-h. Plasma concentration of PYY raised (126 +/- 10 pg/ml) after the administration of bombesin (400 pmol/kg-h, IV). Bile enhanced release of PYY. The present study suggests a hormonal role for PYY.

The presence or absence of tissular polypeptide antigen (TPA) in the culture medium of hormone dependent breast cancer tumoral cells, the relationship between TPA concentration and cellular proliferative activity, have been investigated as well as whether TPA levels change in response to steroid preparations or the action of different antiestrogens. Results show that in MCF-7 cell line culture media, proteins antigenically related to TPA can be detected in concentrations which parallel the number of cells in culture. Consequently, TPA can be considered a cell proliferation marker. Hydroxy-tamoxifen at a concentration of 10(-7) M inhibited both cell proliferation and TPA antigen release, while the relative proportion between number of cells (valued by DNA quantification) and TPA concentration remained unchanged.