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Biomedical subjects

M Navarro

Publications and source records attributed to M Navarro.

At least 109 records · Page 6Linked to original sources

Does treatment of bladder dysfunction prior to renal transplant improve outcome in patients with posterior urethral valves?

Fourteen patients with posterior urethral valves and end-stage renal failure were urodynamically evaluated in order to identify and correct any bladder dysfunction before renal transplant. Of the 14 patients, during filling, six had normal bladder function, two had an over-distended bladder (one with instability), one had instability, four had poor compliance, and one had a very reduced bladder capacity. During the voiding phase, one had a myogenic failure and another had detrusor-sphincteric dyssynergia. Four patients underwent bladder augmentation. Three were managed with anticholinergic therapy and two required clean intermittent catheterization owing to post-voiding residual urine. A renal transplant was performed in all of these patients at a mean age of 8.2 years. We compared outcome in these 14 patients with bladder dysfunction treated before transplantation with outcome in a matched control group of 14 transplant patients. Graft function and survival were similar in both groups. We believe that urodynamic studies must be included in the pretransplant evaluation of patients with posterior urethral valves in order to diagnose any bladder dysfunction and commence appropriate treatment to avoid any negative influence on graft function.

Adolescent↗

Increased serum levels of soluble L-selectin (CD62L) in patients with active systemic lupus erythematosus (SLE).

The adhesion molecule L-selectin (CD62L) mediates lymphocyte recirculation and leucocyte rolling on vascular endothelium at sites of inflammation. Serum levels of soluble L-selectin (sL-selectin) were measured in patients with SLE in order to relate these levels to clinical activity and immunological parameters. An ELISA was used to detect the soluble form of human L-selectin (CD62L) in 42 patients with SLE and in 33 healthy individuals. The mean +/- s.e.m. values of sL-selectin were 1285 +/- 121 ng/ml for patients with SLE and 986 +/- 180 ng/ml for healthy blood donors, but there was no significant difference. When patients with active SLE were analysed, higher levels of circulating sL-selectin were found when compared with patients without activity (1497 +/- 167 ng/ml versus 941 +/- 150 ng/ml; P = 0.028). We found a significant correlation between the levels of sL-selectin and of dsDNA antibodies (r = 0.36, P = 0. 044) and between levels of sL-selectin and SLE Disease Activity Index (SLEDAI) score (r = 0.42, P = 0.003). Patients with active SLE studied cross-sectionally showed significant elevations of sL-selectin (CD62L) compared with controls. Thus, the levels of this soluble adhesion molecule correlated with active disease and levels of anti-dsDNA antibodies.

Adolescent↗

Peripheral versus central effects of glucagon-like peptide-1 receptor agonists on satiety and body weight loss in Zucker obese rats.

The present study explores the potential utility of peripheral versus central administration of glucagon-like peptide-1 (GLP-1) receptor agonists in the regulation of feeding behavior in Wistar and Zucker obese rats. Acute central (intracerebroventricular [i.c.v.]) and peripheral (subcutaneous [s.c.]) administration of both GLP-1 (7-36) amide and exendin-4 resulted in a reduction in food intake for at least 4 hours, exendin-4 being much more potent than GLP-1 (7-36) amide, especially after peripheral administration. Both Zucker obese rats (fa/fa) and their lean littermates (Fa/-) responded to acute central and peripheral administration of exendin-4. Moreover, in situ hybridization revealed specific labeling for the mRNA for GLP-1 receptors in several brain areas of both the obese and lean rats. The presence of this receptor was also detected by affinity cross-linking assays. Long-term s.c. administration of exendin-4 (1 single injection per day, 1 hour prior to the onset of the dark phase of the cycle) decreased daily food intake and practically blocked weight gain in obese rats. In contrast to previous studies, these findings show that peripheral (s.c.) administration of both GLP-1 receptor agonists also induces satiety and weight loss in rats, and suggest the potential usefulness of exendin-4 as a therapeutic tool for the treatment of diabetes and/or obesity.

Amines↗

Primary tuberculous chancre caused by Mycobacterium bovis after goring with a bull's horn.

A 14-year-old boy was gored by a bull during festival celebrations. The horn of the bull caused a wound on his left hand and after 3 months it was a accompanied by an ulcerated nodule on the left upper arm and an axillary adenopathy. The tuberculin test was positive and a culture of the aspiration biopsy specimen of the axillary lymph node yielded Mycombacterium bovis.

Adolescent↗

Single-tube balanced heminested PCR for detecting Mycobacterium tuberculosis in smear-negative samples.

In order to achieve more sensitive and specific results for the rapid diagnosis of tuberculosis, we have developed a new method, named balanced heminested PCR, which avoids the inconvenience of asymmetric amplification and has the advantages of single-tube heminested PCR. This was achieved by replacing the outer primer that participates in both rounds of amplification in the standard heminested technique by another primer containing the sequence of the inner primer attached at its 5' end. When both techniques were tested for the IS6110 target of Mycobacterium tuberculosis complex in 80 smear-negative culture-positive sputum samples and 60 control samples, the results showed 100% specificity for both techniques and sensitivities of 60 and 75% for heminested PCR and balanced heminested PCR, respectively (P = 0.02). In conclusion, the balanced heminested technique shows a higher sensitivity than that of the standard heminested, and it could be applied to any PCR by attaching the inner primer at the 5' end of the opposite outer primer. Thus, the balanced heminested technique provides a target for the inner primer in both strands, avoiding asymmetric amplification and thereby resulting in a more efficient amplification, and, in practice, a higher sensitivity without loss of specificity and with a minimum risk of cross-contamination.

DNA Transposable Elements↗

Maternal exposure to the synthetic cannabinoid HU-210: effects on the endocrine and immune systems of the adult male offspring.

Natural and synthetic cannabinoid receptor agonists have been described to exert profound effects on both the neuroendocrine integration and the functional responses of the immune system. In the present study, Wistar rats were exposed to the highly potent cannabinoid agonist HU-210 (1, 5 and 25 microg/kg) during gestation and lactation and the ensuing effects on several endocrine and immune parameters of the adult male offspring were analyzed. Perinatal exposure to HU-210 partially affected the distribution of lymphocyte subpopulations in the spleen and peripheral blood. The major changes observed occur after maternal exposure to the 25 microg/kg dose of HU-210. There was a reduction in the T-helper subpopulation in the spleen and a dose-related decrease in the rate of T(helper)/T(cytotoxic) in peripheral blood lymphocytes. Concanavalin-A and lipopolysaccharide-induced proliferation were normal in all the groups tested. In the same animals, perinatal exposure to HU-210 did not affect basal levels of growth hormone, IGF-1, prolactin, or follicle-stimulating hormone. Basal values of luteinizing hormone were elevated in animals given the 1 microg/kg dose of HU-210. Corticosterone levels were reduced in the animals exposed to the higher dose of HU-210 during gestation and lactation. These animals exhibited a decreased responsiveness of the hypothalamo-pituitary-adrenal (HPA) axis to the stimulation with a single injection of HU-210 (20 microg/kg, i.v.) at adult ages, which may reflect the onset of long-lasting tolerance to the HPA-activating properties of cannabinoids. The opposite pattern of response was found in the animals given the 1 microg/kg dose, in which a sensitization of the corticosterone response to acute HU-210 was observed. The present work reveals that maternal exposure to cannabinoids results in minor changes in the development of the immune system, but may induce long-lasting alterations in the functional status of the HPA axis.

Administration, Oral↗

Autologous blood transfusion as an immunomodulator in experimental sepsis.

BACKGROUND: Homologous blood transfusion is associated with immunosuppressive consequences. Some clinical and experimental studies have suggested an immunostimulating action of autologous blood transfusion. The aim of this paper is to ascertain the effects of either homologous blood transfusion or autologous blood transfusion on the lymphocyte subsets and cytokines in a model of intra-abdominal sepsis. MATERIALS AND METHODS: There were three study groups. Group A: 10 Wistar-Furth (WF) rats underwent cecal ligation and puncture (CLP) aimed at causing an intra-abdomial sepsis; Group B: 10 WF rats underwent CLP plus 1 ml homologous blood perioperative transfusion obtained from Fisher-344 rat while Group C: 10 WF rats underwent CLP plus 1 ml autologous blood perioperative transfusion. Changes of peripheral lymphocyte subsets, percentages of total T-lymphocytes (CD3), Helper T-lymphocytes (CD4), supressor/cytotoxic T-lymphocytes (CD8), CD4/CD8 ratio, Interleukin-2 receptor expression (IL-2R) and cytokines IL-1 and TNF-alpha were measured in peripheral blood on the preoperative, 1st, 3rd and 7th postsepsis (PO) days. RESULTS: Rats in homologous transfused group showed a decrease of %CD4 on the 3rd PO (from preoperative to 3rd PO;p < 0.01; and from 1st to 3rd PO; p < 0.05) and on the 7th PO (from preoperative to 7th PO; p < 0.05); %CD8 increased from preoperative to 3rd PO (p < 0.05), from 1st to 3rd PO (p < 0.01) and from 1st to 7th PO (p < 0.05). An initial decrease on day 1 (p < 0.01) followed by an increase on the 3rd PO (p < 0.01) with regard to IL-2R and a significant increase of IL-1 levels within the first 24h (p < 0.01). Rats in autologous transfused group showed an increase of %CD3 from preoperative to 7th PO (p < 0.05), and from 3rd to 7th PO (p < 0.01). CONCLUSIONS: We observed that homologous blood transfusions induce a greater alteration in the cellular immune response and of the cascade of cytokines than autologous transfusions. This modulates the variations of the immune response induced by sepsis.

Animals↗

PTEN tumour suppressor is linked to the cell cycle control through the retinoblastoma protein.

The tumour suppressor PTEN, also named MMAC1 or TEP1, is associated with a number of malignancies in human populations. This protein has a dual protein phosphatase activity, being also capable to dephosphorylate phosphatidylinositol 3,4,5 triphosphate. We have studied the mechanism of growth suppression attributable to PTEN. We observed that PTEN overexpression inhibits cell growth in a variety of normal and transformed, human and murine cells. Bromodeoxyuridine (BrdU) incorporation and TUNEL labelling experiments in transiently transfected cells demonstrate that this inhibition is due to a cell cycle arrest rather than induction of apoptosis. Given that PTEN is unable to cause cell growth arrest in retinoblastoma (Rb)-deficient cell lines, we have explored the possible requirement for pRb in the PTEN-induced inhibition of cell proliferation. We found that the co-expression of SV40 antigen, but not a mutant form (which binds exclusively to p53), and cyclin D1/cdk4 are able to overcome the PTEN-mediated growth suppression. In addition, the reintroduction of a functional pRb, but not its relatives p107 or p130, in Rb-deficient cells restores the sensitivity to PTEN-induced arrest. Finally, the hyperphosphorylation of transfected pRb is inhibited by PTEN co-expression and restored by PI-3K co-expression. Accordingly, PTEN gene is mostly expressed, in parallel to Akt, in mid-late G1 phase during cell cycle progression prior to pRb hyperphosphorylation. Finally, we have studied the signal transduction pathways modulated by PTEN expression. We found that PTEN-induced growth arrest can be rescued by the co-expression of active PI-3K and downstream effectors such as Akt or PDK1, and also certain small GTPases such as Rac1 and Cdc42, but not by active Ha-ras, raf or RhoA. Collectively, our data link the tumour suppressor activities of PTEN to the machinery controlling cell cycle through the modulation of signalling molecules whose final target is the functional inactivation of the retinoblastoma gene product.

3T3 Cells↗

Conditional expression of glycosylphosphatidylinositol phospholipase C in Trypanosoma brucei.

Trypanosoma brucei glycosylphosphatidylinositol phospholipase C (GPIPLC) is expressed in the bloodstream stage of the life cycle, but not in the procyclic form. It is capable of hydrolyzing GPI-anchored proteins and phosphatidylinositol (PI) in vitro. Several roles have been proposed for GPIPLC in vivo, in the release of variant surface glycoprotein during differentiation or in the regulation of GPI and PI levels, but none has been substantiated. To explore GPIPLC function in vivo, tetracycline-inducible GPIPLC gene (GPIPLC) conditional knock-out bloodstream form and tetracycline-inducible GPIPLC-expressing procyclic cell lines were constructed. We were unable to generate GPIPLC null mutants. Cleavage of GPI-anchored proteins was abolished in extracts from uninduced conditional knock-outs and was restored upon induction. Despite the barely detectable level of GPIPLC activity in uninduced conditional knock-out bloodstream forms, their growth was not affected. GPI-protein cleavage activity could be induced in procyclic cell extracts, up to wild-type bloodstream levels. Myo-[3H]inositol incorporation into [3H]inositol monophosphate was about 14-fold lower in GPIPLC conditional knock-out bloodstream forms than in the wild type. Procyclic cells expressing GPIPLC showed a 28-fold increase in myo-[3H]inositol incorporation into [3H]inositol monophosphate and a 1.5-fold increase in [3H]inositol trisphosphate levels, suggesting that GPIPLC may regulate levels of inositol phosphates, by cleavage of PI and phosphatidylinositol 4,5-bisphosphate.

Animals↗

Effects of delta9-THC on VIP-induced prolactin secretion in anterior pituitary cultures: evidence for the presence of functional cannabinoid CB1 receptors in pituitary cells.

Peripheral administration of cannabinoid CB1 receptor agonists to laboratory rats induce a brief rise in plasma prolactin (PRL) levels followed by a prolonged decrease in PRL secretion from the pituitary. While the inhibitory component of this biphasic response depends on the cannabinoid-induced activation of dopamine release from hypothalamic terminals located in the median eminence, the neurobiological mechanisms underlying the activation phase of PRL release remains to be explained. In the present study the possible direct effect of the cannabinoid receptor agonist delta9-Tetrahydrocannabinol (THC) on prolactin secretion and cAMP accumulation was examined in anterior pituitary cultures. THC (0.1 and 1 microM) increased cAMP levels, and induced PRL release (1 and 10 mu). THC did not affect vasoactive intestinal peptide (VIP, 0.5 microM) induced cAMP accumulation in pituitary cultures, showing additive effects at THC 1 microM concentration. However, THC did prevent VIP-dependent increases in prolactin secretion. These results indicate that THC, through a direct pituitary action, activates both the synthesis of cAMP and PRL release and interferes with intracellular mechanisms involved in PRL secretion by VIP. These actions could be mediated through cannabinoid CB1 receptors which were found to be present in anterior pituitary cells, including lactotrophs, as revealed by immunocytochemistry with a specific polyclonal antibody raised against the CB1 receptor protein.

Animals↗

Frameshift mutations at mononucleotide repeats in caspase-5 and other target genes in endometrial and gastrointestinal cancer of the microsatellite mutator phenotype.

The majority of tumors from hereditary nonpolyposis colorectal cancer families and a subset of unselected gastrointestinal and endometrial tumors exhibit a microsatellite mutator phenotype (MMP) that leads to the accumulation of hundreds of thousands of clonal mutations in simple repeat sequences. The mutated genes with positive or negative roles in cell growth or survival in aneuploid gastrointestinal cancer (e.g., APC, K-ras, and p53) are less frequently mutated in near-diploid MMP gastrointestinal tumors. These tumors accumulate mutations in other genes, such as DNA mismatch repair hMSH3 and hMSH6, transforming growth factor-beta type II receptor, and BAX. All these genes carry, within their coding sequences, mononucleotide repeats that are preferred targets for the MMP. Endometrial carcinoma is the most common type of extracolonic neoplasia in the hereditary nonpolyposis colorectal cancer syndrome, but the spectrum of its target cancer genes is not well characterized. Here, we report that endometrial cancer of the MMP also accumulates mutations in genes that are typically mutated in gastrointestinal cancer of the mutator pathway, including BAX (55%), hMSH3 (28%), and hMSH6 (17%). We also report the detection of frameshift mutations in caspase-5, a member of the caspase family of proteases that has an (A)10 repeat within its coding region, in MMP tumors of the endometrium, colon, and stomach (28, 62, and 44%, respectively). We therefore suggest caspase-5 as a new target gene in the microsatellite mutator pathway for cancer.

Caspases↗

Trypanosoma brucei variant surface glycoprotein regulation involves coupled activation/inactivation and chromatin remodeling of expression sites.

Trypanosoma brucei is an extracellular protozoan parasite that cycles between mammalian hosts and the tsetse vector. In bloodstream-form trypanosomes, only one variant surface glycoprotein gene (VSG) expression site (ES) is active at any time. Transcriptional switching between ESs results in antigenic variation. No VSG is transcribed in the insect procyclic stage. We have used bacteriophage T7 RNA polymerase (T7RNAP) to study the transcriptional accessibility of ES chromatin in vivo. We show that T7RNAP-mediated transcription from chromosomally integrated T7 promoters is repressed along the entire length of the ES in the procyclic form, but not in the bloodstream form, suggesting that the accessible chromatin of inactive bloodstream-form ESs is remodeled upon differentiation to yield a structure that is no longer permissive for T7RNAP-mediated transcription. In the bloodstream form, replacing the active ES promoter with a T7 promoter, which is incapable of sustaining high-level transcription of the entire ES, prompts an ES switch. These data suggest two distinct mechanisms for ES regulation: a chromatin-mediated developmental silencing of the ES in the procyclic form and a rapid coupled mechanism for ES activation and inactivation in the bloodstream form.

Animals↗

Pelvic insufficiency fractures in patients with pelvic irradiation.

BACKGROUND: Insufficiency fractures (IF) occur as a result of normal physiological stress on bones with deficient elastic resistance. Pelvic insufficiency fractures are a complication of osteoporosis due to postmenopausal status, high dose of corticosteroids, or local irradiation. They are important because differential diagnosis includes pelvic bone metastases. Diagnosis is based on both clinical manifestations and radiographic and scintigraphic findings. METHODS AND MATERIALS: We examined eight patients with pelvic cancer who had previously undergone external beam radiation therapy as part of their treatment. In the follow-up, they developed insufficiency fractures, and no factor other than pelvic irradiation was present. Diagnosis was confirmed by radionuclide bone scan followed by conventional radiography and computed tomography (CT) scan. RESULTS: The average onset of symptoms was 13.7 months after radiation therapy was completed. The initial symptom in all cases was pain. In all of the patients, the bone scan showed abnormalities. One to four increased uptake foci were observed, in the sacroiliac joint in all cases, and in the pubis in three cases. The initial diagnosis was bone metastases in five patients. CT scan showed fractures in all of the patients, in sacrum and pubis, both endostic and cortical. Treatment, consisting of nonsteroidal anti-inflammatory drugs and rest, led to symptomatic relief in all cases. CONCLUSION: Knowledge of pelvic insufficiency fractures is essential in order to rule out metastasic disease, and thus avoid inaccurate treatment. Although radionuclide bone scan is useful in early detection of pelvic IF, definitive diagnosis is provided by CT scan.

Adenocarcinoma↗

Chronic (-)-delta9-tetrahydrocannabinol treatment induces sensitization to the psychomotor effects of amphetamine in rats.

Clinical and basic research studies have linked cannabinoid consumption to the onset of psychosis, specially schizophrenia. In the present study we have evaluated the effects of the natural psychoactive constituent of Cannabis (-)-delta9-tetrahydrocannabinol on the acute actions of the psychostimulant, D-amphetamine, on behaviour displayed by male rats on a hole-board, a proposed animal model of amphetamine-induced psychosis. Cannabinoid-amphetamine interactions were studied (1) 30 min after acute injection of (-)-delta9-tetrahydrocannabinol (0.1 or 6.4 mg/kg, i.p.); (2) 30 min after the last injection of 14-daily treatment with (-)-delta9-tetrahydrocannabinol (0.1 or 6.4 mg/kg) and 3) 24 h after the last injection of 14-daily treatment with (-)-delta9-tetrahydrocannabinol (6.4 mg/kg). Acute cannabinoid exposure antagonized the amphetamine-induced dose-dependent increase in locomotion, exploration and the decrease in inactivity. Chronic treatment with (-)-delta9-tetrahydrocannabinol resulted in tolerance to this antagonistic effect on locomotion and inactivity but not on exploration, and potentiated amphetamine-induced stereotypies. Lastly, 24 h of withdrawal after 14 days of cannabinoid treatment resulted in sensitization to the effects of D-amphetamine on locomotion, exploration and stereotypies. Since (-)-delta9-tetrahydrocannabinol is a cannabinoid CB1 receptor agonist, densely present in limbic and basal ganglia circuits, and since amphetamine enhances monoaminergic inputs (i.e., dopamine, serotonin) in these brain areas, the present data support the hypothesis of a role for the cannabinoid CB1 receptor as a regulatory mechanism of monoaminergic neuron-mediated psychomotor activation. These findings may be relevant for the understanding of both cannabinoid-monoamines interactions and Cannabis-associated psychosis.

Amphetamine↗

Renal ischemia-induced increase in vascular permeability is limited by hypothermia.

The purpose of the present work was to evaluate the kallikrein-kinin system and effects of hypothermia during renal ischemia and reperfusion. Male C57BL/KSJmdb mice were subjected to 20 or 60 min ischemia for different periods of reperfusion. Our results demonstrate that short periods of ischemia followed by reperfusion did not cause significant alterations in kallikrein activity, Evans Blue (EB) extravasation, prokallikreins, myeloperoxidase activity or plasma creatinine concentration. Edema was evident at 1 h reperfusion in the treated mice, but returned to basal values after 24 h reperfusion. Kallikrein activities and EB extravasation showed a significant increase in 60 min ischemic mice. Myeloperoxidase activity in the kidney of the mice confirmed net infiltration in the group with 60 min ischemia and 24 h reperfusion. The generation of kinins and activation of matrix degrading enzymes by tissue kallikrein, liberated from both renal and infiltrated leukocytes, could be responsible at least in part for the damage observed in the kidney of mice subject to 60 min ischemia and reperfusion. The hypothermia significantly reduced the inflammatory process in the 60 min ischemic mice, and did prevent an increase in vascular permeability. Nevertheless, the tissue edema was not shown to change between normothermic and hypothermic ischemic mice.

Animals↗