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Biomedical subjects

R Salazar

Publications and source records attributed to R Salazar.

At least 55 records · Page 3Linked to original sources
PubMed1995

Glutamate-receptor elicited acetylcholinesterase release in mouse spinal cord slice: a model of early excitotoxic injury.

To investigate the mechanisms by which glutamate-induced acetylcholinesterase (AChE) release might play a part in the pathogenesis of excitotoxically triggered motor neurone disease, we measured AChE molecular forms released after glutamate-receptor agonist stimulation of superfused and incubated slices of mouse spinal cord. Kainate and GLU caused a dose-related, calcium-dependent, magnesium-blocked liberation of AChE soluble forms (mainly G4) from both the ventral and dorsal horns, without membrane damage. In the immature slice, glycine potentiated GLU elicited AChE release in the presence of strychnine, suggesting N-methyl-D-aspartate (NMDA) receptor involvement. After the 30th postnatal day, nearly all the release was caused by non-NMDA receptor stimulation. The response might interfere with the negative feedback loop which modulates the overactivation of motor neurones, and might render them more vulnerable to excitotoxic stress.

Acetylcholinesterase↗
PubMed1995

Expression of biologically active human factor IX in human hematopoietic cells after retroviral vector-mediated gene transduction.

Gene therapy is a potential treatment for hemophilia, wherein cells transduced with a normal factor IX gene could provide a continuous in vivo source of circulating factor IX. In this study, we examined the potential use of hematopoietic cells as a target for factor IX gene therapy. Human myeloid leukemia cells (HL-60) were transduced by retroviral vectors carrying a normal human factor IX cDNA under control of either the Moloney murine leukemia virus long terminal repeat (MoMuLV LTR) (LIXSN), the SV40 promoter (LNSVIX), or a cytomegalovirus (CMV) promoter (LNCIX). Factor IX production was measured in the transduced cells both in the uninduced state and after induction of granulocytic differentiation [with dimethylsulfoxide (DMSO)] or monocytoid differentiation [with phorbol myristic acetate (PMA)]. Transcription of factor IX from the MoMuLV LTR was seen in all cells, with a two-fold increase upon differentiation. Induction with PMA led to an 8- to 15-fold increase in factor IX transcripts from an internal CMV promoter. No factor IX transcripts from the internal SV40 promoter were detected. Immunoreactive factor IX protein was identified by Western blot from induced HL-60 cells transduced by either LIXSN or LNCIX. Factor IX production by HL-60 cells transduced by LNCIX ranged from 38-93 ng/10(6) cells/24 hr following induction of monocytic differentiation. The factor IX antigen titer was directly related to factor IX coagulant titer (r = 0.98; p < 0.001). These data indicate that human myelomonocytic cells are capable of performing the necessary post-translational modifications to produce functional factor IX.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Northern↗
PubMed1991

[Immunological defects in septic shock. Deficiency of natural Killer cells and T-lymphocytes].

It is well known that an immunosuppressive response occurs after acute trauma. Some cellular mediators participate in the pathogenesis of septic shock. However, the exact role of the lymphocyte subsets and natural killer (NK) activity in this condition is not clear. We studied NK cytolytic activity through a 51Cr liberation assay using K-562 target cells in 20 patients with initial septic shock (10 men and 10 females, mean age 41 years old). Lymphocyte subsets CD3 (T3), CD4 (T4), CD8 (T8), CD16 (Leu-11) and CD56 (Leu-19) were also studied by indirect immunofluorescence. Compared to results obtained in 20 healthy volunteers, patient's NK activity was decreased (4.6 +/- 3.9 vs 26.1 +/- 10, p less than 0.025), CD16 was lower (10%/187 vs 15%/280 per ul) and CD56 was also lower (6%/120 vs 12%/224 per ul), p less than 0.05. T lymphocyte subsets were also decreased: CD3 cells (1100 vs 1352 per ul) and CD4 cells (634 vs 873 per ul), p less than 0.05. Thus, a severe decrease in NK cells and NK cell function as well as decreases in CD3 and CD4 lymphocyte subsets are present in the initial stages of septic shock. The predictive value of these findings is currently under study.

Adolescent↗
PubMed1990

Modulation of tissue responsiveness to angiotensin-II in hyperprolactinemic subjects.

The present studies were designed to test the hypothesis that hyperprolactinemia modulates target tissue responsiveness to angiotensin-II (AII). Adrenal and pressor responses to AII infusions were determined in six patients with PRL-secreting pituitary microadenomas and in five normal controls during defined electrolyte balance. Hyperprolactinemic and normal subjects had similar mean blood pressures while on a regular Na intake (82.5 +/- 0.5 vs. 81.2 +/- 0.3 mm Hg). However, after 4 days of Na loading (200 meq/day), the mean blood pressure in hyperprolactinemic subjects was higher than that in normal (86.6 +/- 1 vs. 83.4 +/- 0.8 mm Hg; P less than 0.05). In addition, enhancement of the mean blood pressure response to three doses of AII was noted in hyperprolactinemic subjects (P less than 0.05) compared to that in normal subjects. After 4 days of Na restriction (10 meq/day), the mean blood pressure in hyperprolactinemic subjects was similar to that in normal subjects (79.7 +/- 0.6 vs. 78.9 +/- 1 mm Hg). However, despite adequate Na restriction, the pressor response to AII continued to be enhanced (P less than 0.05) in hyperprolactinemic subjects. There were no differences in plasma or urinary electrolytes or in PRA between hyperprolactinemic and normal subjects. Hyperprolactinemic subjects had higher basal (P less than 0.01), AII-stimulated (P less than 0.05), and ACTH-stimulated (P less than 0.02) aldosterone levels during Na loading, but not during Na restriction. The differences disappeared after the correction of the hyperprolactinemia. The data demonstrate significant alterations in adrenal and pressor responsiveness in hyperprolactinemic subjects and suggest a modulating role for PRL on vascular reactivity and steroid biosynthesis. The precise mechanism has not been determined, but may be secondary to PRL-induced up-regulation of adrenal and vascular AII receptors.

Adenoma↗
PubMed1990

[Hemoglobin variants and hematologic and serologic parameters of the population of El Limón (Aragua State, Venezuela)].

Nine hundred and fifty seven individuals from El Limon (Aragua State, Venezuela) were studied, in order to get information on their hematologic, immunologic and biochemical characteristics. The majority of surnames were of Spanish origin although there were also from other European nationalities. No surname from Venezuelan Indians was found. The pathologic hemoglobin variants (Hb S, Hb C and Hb D-Punjab) have a frequency of 4.3%. Eight albumin variants were detected. The hematologic values suggest a high frequency of iron deficiency. Positivity for hepatitis virus B was found in 0.9% of the population. The carriers and patients for hemoglobin variants per generation was calculated for the whole municipality (5062 and 26, respectively). The African component of the population was estimated in around 18%.

Adolescent↗
PubMed1990

Expression of the insulin gene is regulated by opioid peptides.

The effects of the opioid peptides Met- and Leu-enkephalin on the expression of the insulin gene in isolated adult rat islets of Langerhans were examined. Isolated rat islets were maintained under various culture conditions for 26 h. The contents of islet preproinsulin mRNA and the amounts of (pro)insulin biosynthesis were assayed. In the presence of 5 mM glucose the preproinsulin mRNA content was increased by 10(-8) M Met-enkephalin to 198% (p less than 0.001) and by Leu-enkephalin to 145% (p less than 0.001) of the control without enkephalins. The preproinsulin mRNA content was raised in the presence of 5 mM glucose by 10(-10) M significant. These results corresponded with an increase in the (pro)insulin biosynthesis under the same conditions. The biosynthesis of (pro)insulin was strongly decreased by actinomycin D at the glucose and enkephalin concentrations tested. The results demonstrated that there is a dose-dependent stimulation of the insulin gene expression by enkephalins and that the increase in (pro)insulin biosynthesis in isolated pancreatic islets by endogenous opioid peptides occurs mainly on the pretranslational level.

Amino Acid Sequence↗
PubMed1989

[Patients with primary anterior uveitis. Determination of circulating immune complexes].

The level of circulating immune complexes (CIC) in 31 patients with primary anterior uveitis was determined by an ELISA method (C1q in solid phase). In addition, we measured antinuclear antibodies (ANA), HLAB 27, C3 and C4. Increased levels of CIC were found in 38% of patients (Group I), the remainder had normal levels (Group II). Positive ANA were found in 33% of patients in Group I and 26% of patients in Group II. The clinical findings and course of uveitis was similar in both groups. Chronic uveitis was associated to greater levels of CIC as compared to recurrent uveitis among patients in Group I (p less than 0.0001). Also, moderate sequelae from uveitis were associated to higher CIC levels.

Adolescent↗
PubMed1989

[T-lymphocyte subpopulations in acute viral hepatitis].

The variability of the clinical course in viral hepatitis depends more on the immune response of the host that on the type of virus involved. Inductors/helpers (LT4) or cytotoxic/suppressors (LT8) T-lymphocytes regulate the immune response which can be modified during infection or in homosexuals who are at high risk for viral infection. We studied 45 males with viral hepatitis (25 B, 13 A, and 7 non A-non B hepatitis), 20 normal and 20 homosexual subjects. LT4, LT8 and B lymphocytes were determined by immunofluorescence in peripheral blood. A significant and transient decrease in levels of LT4 was found in A and B hepatitis (670 and 591 per ml vs 873 for normals). In some hepatitis B cases this decrease persisted until the HB serum antigen disappeared. Increased levels of LT8 were found in asymptomatic or hepatitis B infected homosexuals (682 and 782 respectively vs 506 per ml in normals). No difference from normals were found in non A-non B hepatitis. B lymphocytes were normal in all groups. Serum factors acting as immunoregulators of suppressors of LT4 function may be involved in the delayed synthesis of anti-HB serum antibody.

Acute Disease↗
PubMed1988

Evaluation of the hypothalamic-pituitary-adrenal axis immediately after pituitary adenomectomy: is perioperative steroid therapy necessary?

Patients undergoing pituitary adenomectomy are usually given glucocorticoid therapy, although there are no data to document the need for such therapy. We prospectively studied hypothalamic-pituitary-adrenal axis (HPA) function in 88 consecutive pituitary adenoma patients before and after selective adenomectomy, excluding those with corticotroph adenomas. Preoperatively, 5 patients had adrenal insufficiency (AI); they were treated with glucocorticoids and excluded from the analysis. The remaining 83 patients had normal HPA function preoperatively and were not given glucocorticoids before, during, or immediately after surgery, but were closely monitored, and their serum cortisol levels were measured in the immediate postoperative period. Two patients were clinically suspected to have AI postoperatively and were treated accordingly. The remaining 81 patients had no clinical manifestations of AI and received no glucocorticoid therapy. Their serum cortisol levels in the immediate postoperative period were appropriately elevated. The mean serum cortisol level was 40.5 +/- 11.1 (+/- SD) micrograms/dL (1117 +/- 306 nmol/L) 6 h after surgery; serum cortisol levels decreased gradually thereafter. Morning serum cortisol levels were within the normal range on the fourth, fifth, and sixth days after surgery: day 4, 15.1 +/- 7.0 micrograms/dL (417 +/- 193 nmol/L); day 5, 16.4 +/- 5.6 micrograms/dL (453 +/- 155 nmol/L); and day 6, 16.3 +/- 5.7 micrograms/dL (450 +/- 157 nmol/L). When tested 3 months after surgery, all 81 patients had normal HPA function. We conclude that HPA function is rarely compromised after selective pituitary adenomectomy. Close observation and serum cortisol measurements in the immediate postoperative period can reliably predict the integrity of the HPA after surgery. Routine glucocorticoid therapy is not needed in patients undergoing selective adenomectomy whose preoperative adrenal function is normal.

Adenoma↗
PubMed1987

Value of growth hormone dynamics and somatomedin C (insulin-like growth factor I) levels in predicting the long-term benefit after transsphenoidal surgery for acromegaly.

Transsphenoidal microsurgery has been shown to be effective in the management of human growth hormone (hGH)-secreting pituitary adenomas. We have previously demonstrated the usefulness of hGH dynamic testing (oral glucose tolerance, insulin hypoglycemia, and thyrotropin-releasing hormone stimulation test) in evaluating the completeness of removal of the adenomas. In patients with acromegaly, serum insulin-like growth factor I (IGF-I) levels are known to correlate with the activity of the disease. We studied the dynamics of hGH secretion in 43 patients with hGH-secreting adenomas 2 to 3 months after surgery. In addition, serum IGF-I levels were recently measured in frozen sera obtained from these patients at the time of dynamic testing. Of the 43 patients undergoing surgery, 19 had normal basal hGH levels as well as dynamics (group I). Two additional patients had low or undetectable hGH levels and were hypopituitary (group II). These 21 patients were considered cured and had no evidence for recurrence of their disease during a mean follow-up period of 97 months. Serum IGF-I levels were normal in 19 (group I) and low in the remaining two patients (group II). Nine additional patients had normal basal hGH levels but abnormal dynamics of secretion (group III). Serum IGF-I levels were normal postoperatively in seven of eight patients tested in this group. During the follow-up period in these nine patients (group III), biochemical and clinical recurrence of acromegaly developed in five. The remaining 13 patients had persistent elevation of basal hGH levels, and all samples tested (n = 8) had elevated IGF-I levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Acromegaly↗
PubMed1984

Modification of the theophylline radioimmunoassay.

The routine utilization of a commercially available radioimmunoassay (RIA) for theophylline (GammaDab), although reliable, is currently prohibited by the high cost of the reagents. In an effort to reduce these costs we have diluted the [125I]theophylline tracer and theophylline antiserum reagents by one-half, contrary to the manufacturer's recommendations. We have demonstrated that an excellent correlation exists (r = 0.968) between our modified RIA method and a conventional high-performance liquid chromatographic technique, despite reagent dilution. Accordingly, our reagent costs have been reduced by half. We conclude that the GammaDab kit reagents can be diluted twofold and still provide an accurate determination of serum theophylline. We must also emphasize that any further alteration(s) of this theophylline RIA procedure would require a thorough evaluation before its routine use could be substantiated.

Chromatography, High Pressure Liquid↗