Search PubMed⌕ Search

Biomedical subjects

A Fernandez

Publications and source records attributed to A Fernandez.

At least 73 records · Page 4Linked to original sources
PubMed1998

Characterization of angiotensin-(1-7) in the urine of normal and essential hypertensive subjects.

A total of 31 healthy volunteers [39 +/- 7 (SD) years] and 18 untreated essential hypertensive subjects [43 +/- 9 years] collected urine for 24 h after a physical examination and laboratory tests. Radioimmunoassay measurements of angiotensin-(1-7) [Ang-(1-7)] in urine and plasma were done as described previously. Sitting systolic and diastolic blood pressures (+/- SD) averaged 118 +/- 11/74 +/- 7 mm Hg and 146 +/- 16/96 +/- 8 mm Hg in normal and essential hypertensive subjects, respectively (P < .001), whereas 24 h urinary volume was not different in normal and essential hypertensive subjects (P > .05). The concentration of Ang-(1-7) in the urine of normal subjects averaged 62.6 +/- 22.6 pmol/L corresponding to a urinary excretion rate of 98.9 +/- 44.7 pmol/24 h. Concurrent measurements of plasma Ang-(1-7) showed that the content of Ang-(1-7) in urine was 2.5-fold higher than that measured in the plasma. In contrast, untreated essential hypertensive subjects had lower concentrations and 24 h urinary excretion rates of Ang-(1-7) averaging 39.4 +/- 18.0 pmol/L and 60.2 +/- 14.6 pmol/24 h, respectively, (P < .001). Differences in the excretory rate of Ang-(1-7) between normal volunteers and essential hypertensive subjects were not modified by normalization of the data by urinary creatinine excretion rates. Urinary concentrations of Ang-(1-7) correlated inversely with systolic, diastolic and mean arterial pressures (r = -0.48, P < .001). Both urinary Ang-(1-7) [odds ratio of 0.92 (95% CI: 0.88-0.97)] and age were independent predictors of systolic blood pressure. These studies demonstrated the presence of Ang-(1-7) in urine and the existence of reduced levels of the heptapeptide in individuals with untreated essential hypertension. The relatively higher concentrations of Ang-(1-7) in urine compared to plasma agrees with data that showed that Ang-(1-7) may contribute to the regulation of blood pressure. The inverse association between Ang-(1-7) and arterial pressure provides a potential marker for the characterization of forms of essential hypertension associated with reduced production or activity of vasodilator hormones.

Adult↗
PubMed1998

Impact of season and discharge weight on complications and growth of Kangaroo Mother Care treated low birthweight infants in Mozambique.

This study aimed to determine the impact of season and weight at discharge on growth rate and complications in low birthweight infants treated with Kangaroo Mother Care (KMC) in Maputo, Mozambique. The study population included 246 infants of birthweight < 2000 g. Follow-up until 2400 g was obtained in 64%. There were no seasonal differences in weight gain and the risk of complications of infants treated with KMC in hospital. During the cold season after discharge, the risk of serious complications, including death, was higher (risk ratio 1.96; p = 0.02) and more readmissions occurred (risk ratio 2.77; p = 0.04). We postulate that after discharge mothers are unable to comply with the kangaroo position at all hours of the day and that exposure to low ambient temperatures may explain the more frequent occurrence of complications in the cold season. The weight at discharge did not affect complications or growth rate. We conclude that the current policy to discharge infants when having gained weight on 3 consecutive days, regardless of the actual weight, or whether the weight at birth has been regained, is adequate. In the cold season particularly, more efforts may be needed to ensure compliance with kangaroo position after discharge and to educate mothers on early signs of complications such as bronchopneumonia to encourage timely care seeking. With this method, low birthweight infants can grow adequately.

Analysis of Variance↗
PubMed1998

RhoA GTPase and serum response factor control selectively the expression of MyoD without affecting Myf5 in mouse myoblasts.

MyoD and Myf5 belong to the family of basic helix-loop-helix transcription factors that are key operators in skeletal muscle differentiation. MyoD and Myf5 genes are selectively activated during development in a time and region-specific manner and in response to different stimuli. However, molecules that specifically regulate the expression of these two genes and the pathways involved remain to be determined. We have recently shown that the serum response factor (SRF), a transcription factor involved in activation of both mitogenic response and muscle differentiation, is required for MyoD gene expression. We have investigated here whether SRF is also involved in the control of Myf5 gene expression, and the potential role of upstream regulators of SRF activity, the Rho family G-proteins including Rho, Rac, and CDC42, in the regulation of MyoD and Myf5. We show that inactivation of SRF does not alter Myf5 gene expression, whereas it causes a rapid extinction of MyoD gene expression. Furthermore, we show that RhoA, but not Rac or CDC42, is also required for the expression of MyoD. Indeed, blocking the activity of G-proteins using the general inhibitor lovastatin, or more specific antagonists of Rho proteins such as C3-transferase or dominant negative RhoA protein, resulted in a dramatic decrease of MyoD protein levels and promoter activity without any effects on Myf5 expression. We further show that RhoA-dependent transcriptional activation required functional SRF in C2 muscle cells. These data illustrate that MyoD and Myf5 are regulated by different upstream activation pathways in which MyoD expression is specifically modulated by a RhoA/SRF signaling cascade. In addition, our results establish the first link between RhoA protein activity and the expression of a key muscle regulator.

3T3 Cells↗
PubMed1998

Primary immunosuppression with mycophenolate mofetil and antithymocyte globulin for kidney transplant recipients of a suboptimal graft.

BACKGROUND: In renal transplantation the beneficial immunosuppressive effects of cyclosporin (CsA) may be curtailed by its nephrotoxicity, specially in patients receiving a cadaveric allograft from suboptimal donors or at risk of delayed graft function. Mycophenolate mofetil (MMF) and antithymocyte globulin (ATG) have each demonstrated to be potent immunosuppressants in renal transplantation. In a prospective analysis we have studied the results at 6 months of the combination of MMF, ATG and low-dose steroids in patients with low immunological risk receiving a first cadaveric renal allograft from a suboptimal donor or at risk of delayed graft function. METHODS: Patients with preformed reactive antibodies < 500% receiving a first graft from a suboptimal donor (age > or = 40 years, non-heart-beating, acute renal failure, arterial hypertension) or at risk of delayed graft function (cold ischaemia time > or = 24 h) were eligible for this open single-arm pilot trial. From September 1996 to March 1997 we recruited 17 patients. They were treated with MMF 2 g p.o. preoperatively, and after transplantation at 3 g/day; rabbit ATG i.v. at 2 mg/kg preoperatively, and 1.5 mg/kg/day the first day after transplantation, followed by four doses of 1 mg/kg on alternate days; prednisone was given at 0.25 mg/kg/day and reduced progressively to 0.1 mg/kg/day at 3 months. Primary outcomes were incidence of biopsy-proven acute rejection, delayed graft function, opportunistic infections, graft and patient survival, and the need for introduction of CsA treatment. RESULTS: delayed graft function occurred in two cases (12%). Four of 17 patients (24%) had a biopsy-proven acute rejection (2 grade I and 2 grade II) within the first 3 months after transplantation. CsA was added in two cases with grade II biopsy-proven acute rejection, and in one with grade I biopsy-proven acute rejection. In one patient MMF was replaced by CsA because of gastrointestinal intolerance. Mean serum creatinine 6 months after transplantation was 159+/-59 micromol/1. Cytomegalovirus tissue invasive disease occurred in one patient (6%). At 6 months follow-up all patients are alive with functioning allografts. CONCLUSIONS: These preliminary results suggest that in low-immunological-risk patients who receive a suboptimal renal allograft or at risk of delayed graft function, the combination of MMF, ATG, and steroids is an efficient immunosuppressive regime that may avoid the use of CsA in 70% of the recipients.

Adult↗
PubMed1998

Clinical and serologic follow-up in patients with neuroborreliosis.

The authors performed a clinical and serologic follow-up study after 4.2 +/- 1.2 years in 44 patients with clinical signs of neuroborreliosis and specific intrathecal antibody production. All patients had been treated with ceftriaxone 2 g/day for 10 days. Although neurologic deficits decreased significantly, more than half the patients had unspecific complaints resembling a chronic fatigue syndrome and showed persisting positive immunoglobulin M serum titers for Borrelia in the Western blot analysis.

Antibodies, Bacterial↗
PubMed1998

The role of intergenerational discrepancy of cultural orientation in drug use among Latina adolescents.

The role of intergenerational discrepancy for cultural orientation was examined in the etiology of drug use among Latina adolescents and in the context of family support. Intergenerational discrepancy occurs when a family member of one generation differs from a family member of another generation in cultural identity factors; this is usually manifested in conflict between a first generation child and the immigrant generation parent. It was hypothesized that the Latina adolescents experiencing intergenerational discrepancy might use drugs more frequently than Latina adolescents who were not; and that family support would be an important moderator of the relationship. A sample of 295 ninth and tenth grade Latina students (approximately 80% Mexican-American) from four Los Angeles area schools were surveyed as part of a larger study. In this secondary analysis, a 2 (family support ) x 2 (discrepancy) ANOVA revealed that intergenerational discrepancy was associated with more drug use in certain cases, and that family support did not moderate this relationship. Results partially validate and extend a theoretical model presented by Szapocznik and Kurtines (1980), and indicate a need to focus on cultural variables when intervening in drug use/misuse among Latina adolescents.

Acculturation↗
PubMed1998

Bioequivalence evaluation of 2 different oral formulations of ciprofloxacin in healthy volunteers.

A bioequivalence study of 2 oral formulations of 500 mg tablets of ciprofloxacin was carried out in 24 healthy volunteers according to a single dose, two-sequence, crossover randomized design. Blood samples were taken prior to each administration and at 13 points within 32 hours after the dose, and plasma concentrations of ciprofloxacin were determined by HPLC. The pharmacokinetic parameters Cmax and tmax were obtained directly from plasma data, ke was estimated by log-linear regression, and AUC was calculated by the trapezoidal rule. The pharmacokinetic parameters AUC and Cmax were tested for bioequivalence after log-transformation of data, differences of tmax were evaluated nonparametrically. The 90% standard confidence intervals of the mean values for the test/reference ratios were 0.87-0.97 for AUC and 0.91-1.05 for Cmax, within the bioequivalence acceptable range of 0.80-1.25 limits. So, we conclude that both formulations were found bioequivalent and, therefore, interchangeable.

Administration, Oral↗
PubMed1997

Role of translocation in the activation and function of protein kinase B.

We have investigated the role of subcellular localization in the regulation of protein kinase B (PKB) activation. The myristoylation/palmitylation motif from the Lck tyrosine kinase was attached to the N terminus of protein kinase B to alter its subcellular location. Myristoylated/palmitylated (m/p)-PKBalpha was associated with the plasma membrane of transfected cells, whereas the wild-type kinase was mostly cytosolic. The activity of m/p-PKBalpha was 60-fold higher compared with the unstimulated wild-type enzyme, and could not be stimulated further by growth factors or phosphatase inhibitors. In vivo 32P labeling and mutagenesis demonstrated that m/p-PKBalpha activity was due to phosphorylation on Thr308 and Ser473, that are normally induced on PKB following stimulation of the cells with insulin or insulin-like growth factor-1 (IGF-1). A dominant negative form of phosphoinositide 3-kinase (PI3-K) did not affect m/p-PKBalpha activity. The pleckstrin homology (PH) domain of m/p-PKBalpha was not required for its activation or phosphorylation on Thr308 and Ser473, suggesting that this domain may serve as a membrane-targeting module. Consistent with this view, PKBalpha was translocated to the plasma membrane within minutes after stimulation with IGF-1. This translocation required the PH domain and was sensitive to wortmannin. Our results indicate that PI3-K activity is required for translocation of PKB to the plasma membrane, where its activation occurs through phosphorylation of the same sites that are induced by insulin or IGF-1. Following activation the kinase detached from the membrane and translocated to the nucleus.

Amino Acid Substitution↗
PubMed1997

Bcl-2 inhibits p53 nuclear import following DNA damage.

Bcl-2 is an integral membrane oncoprotein that localizes to membranes of the mitochondria, endoplasmic reticulum, and nuclear envelope. Bcl-2 is a member of a family of cell death regulators and functions to inhibit apoptosis. Using confocal microscopy and immunoblotting we show that the ability of bcl-2 to suppress cell death following genotoxic damage can be a consequence of inhibiting nuclear import of induced wild-type p53 protein. Our data suggests that the ability of bcl-2 to modulate trafficking events is not cell type specific. These data support a 'gatekeeper' mechanism for cell death suppression by bcl-2.

3T3 Cells↗
PubMed1997

Kinins are implicated of the hypotensive effect of acidic fibroblast growth factor.

Acidic fibroblast growth factor causes an acute and transient nitric oxide-dependent hypotensive effect in experimental animals. However, this response is not found, or is very small, in vitro. We hypothesized that plasma mediators, such as kinins, are involved in aFGF-induced hypotension. We studied the hypotensive effect of intravenous aFGF (1 microg) in control Wistar rats, and compared this response to that in Wistar rats treated with a bradykinin receptor antagonist Na-adamantaneacetyl-D-Arg-(Hyp3,Thi5,8,D-Phe7]-brad yki nin), in kininogen-deficient Brown-Norway-Katholiek (BNK) rats, and in rats depleted of kininogen after repeated treatment with ellagic acid. FGF was administered in the jugular vein and mean arterial pressure was measured through a femoral artery catheter. Following treatment with the bradykinin receptor antagonist, the hypotensive effect of aFGF was reduced 38% with 58 microg of antagonist and by 60% with the 420 microg dose (9 +/- 1 vs 22 +/- 3mm Hg, p<0.01). Mean blood pressure decrease was 12 +/- 1 in BNK rats (p<0.01, vs control) and 10 +/- 2 mm Hg in kininogen-depleted ellagic acid-treated rats (p<0.05, vs control). These findings implicate kinins as necessary mediators for the hypotensive effect of aFGF in vivo. A full hypotensive effect of aFGF requires sufficient amounts of kininogens, the precursor molecules of kinins, as well as bradykinin receptors.

Adamantane↗
PubMed1997

Characterization and physiological importance of a novel cell cycle regulated protein kinase in Xenopus laevis oocytes that phosphorylates cyclin B2.

We have partially purified a specific cyclin B2 kinase (cyk) from prophase oocytes of Xenopus laevis after an ATP-gamma-S activation step. Phosphopeptide analysis identified Ser53 as the major in vitro phosphorylation site for cyk in cyclin B2. Using a synthetic peptide derived from cyclin B2 encompassing Ser53 (cyktide) as a substrate, cyk was shown to be activated during progesterone-induced maturation, with a peak of activity between 40 and 50% maturation. A sustained high cyk activity was observed in oscillating egg extracts. Microinjection of cyk-phosphorylated cyclin B2 into prophase oocytes accelerated progesterone-induced maturation by about 2 h, indicating that cyclin B2 is a relevant substrate for cyk and that the function of cyk is situated upstream of cdc2-cyclin B activation. Microinjection of cyk-phosphorylated cyktide or a combination of cyk and cyclin B1 into G2 fibroblasts induced significant changes in cell morphology, reminiscent of a premature prophase-like phenotype. Similarly, addition of cyk-phosphorylated cyktide in cyclin B1-dependent interphase extracts resulted in histone H1 kinase activation.

Adenosine Triphosphate↗
PubMed1997

Herpes simplex virus encephalitis in a renal transplant patient: diagnosis by polymerase chain reaction detection of HSV DNA.

A case of herpes simplex virus (HSV) encephalitis with disseminated primary HSV infection in a renal transplant patient is described. The diagnosis of the disease was achieved by nested polymerase chain reaction (PCR)-DNA in cerebrospinal fluid (CSF). Other diagnostic measures (immunoglobulin [Ig] M and virological cultures both in blood and CSF) were negative. Blood IgG gave a false-positive signal. Although ganciclovir is not the drug of choice, its concomitant administration in our patient as a prophylactic measure against CMV infection may have decreased the usual severity normally expected in this kind of primary HSV infection. The subsequent increase in ganciclovir dose to full therapeutic range, which was implemented before the diagnosis was achieved, led to the disappearance of symptoms. The detection of PCR-DNA in CSF will probably become the diagnostic method of choice. One of its great advantages, in addition to its diagnostic reliability, is that it may obviate the performance of many cerebral biopsies.

Adult↗
PubMed1997

The insulin gene is transcribed in the human thymus and transcription levels correlated with allelic variation at the INS VNTR-IDDM2 susceptibility locus for type 1 diabetes.

Type 1, or insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease associated with loss of tolerance to several pancreatic islet cell molecules, including insulin, glutamic acid decarboxylase (GAD), ICA69 and the tyrosine phosphatase IA-2 (refs 1-3). Among several predisposing loci, IDDM2 maps to the insulin gene (INS) VNTR (variable number of tandem repeats) minisatellite on chromosome 11p15 (refs 4-9). Allelic variation at this VNTR locus correlates with steady-state levels of INS mRNA in pancreas and transfected rodent cell lines, but it is difficult to reconcile the association of lower INS mRNA levels in the pancreas with class III VNTRs that are dominantly protective from IDDM. We show that during fetal development and childhood, mRNAs for insulin and other islet cell autoantigens (GAD, ICA69, IA-2) are expressed at low levels in the human thymus. Critically, we also detect proinsulin and insulin protein. VNTR alleles correlate with differential INS mRNA expression in the thymus where, in contrast to the pancreas, protective class III VNTRs are associated with higher steady-state levels of INS mRNA expression. This finding provides a plausible explanation for the dominant protective effect of class III VNTRs, and suggests that diabetes susceptibility and resistance associated with IDDM2 may derive from the VNTR influence on INS transcription in the thymus. Higher levels of (pro)insulin in the thymus may promote negative selection (deletion) of insulin-specific T-lymphocytes which play a critical role in the pathogenesis of type-1 diabetes.

Aging↗
PubMed1997

A putative human male infertility gene DAZLA: genomic structure and methylation status.

The DAZLA (DAZ Like Autosomal) gene on human chromosome 3 shares a high degree of homology with the DAZ (Deleted in AZoospermia) gene family on the Y chromosome, a gene family frequently deleted in males with azoospermia or severe oligospermia. The involvement of both DAZ and DAZLA in spermatogenesis is suggested by their testis-specific expression and their homology with a Drosophila male infertility gene, boule. Whereas male infertility resulting from deletion of the DAZ genes on the Y chromosome occurs sporadically, that due to a defective DAZLA gene is expected to be inheritable. The fraction of males with idiopathic azoospermia or oligospermia that harbour mutations in the DAZLA gene remains unknown. As a prerequisite for mutation screening, the genomic structure of the DAZLA gene was elucidated and found to consist of 11 exons spanning 19 kh. The exon/intron boundaries are conserved between DAZ and DAZLA. The 5' end of both genes are hypomethylated in spermatozoa but not in leukocytes or placenta, consistent with the expression pattern of the genes. The genomic structure of DAZLA paves the way for mutation detection in families with autosomal recessive male infertility.

Base Sequence↗
PubMed1997

Interactions between the oocyte and cumulus cells in the ovary of the B6.Y(TIR) sex-reversed female mouse.

The XY (B6.Y(TIR)) sex-reversed female mouse is infertile, primarily because of the early death of its embryos. We have previously determined that the XY oocyte itself, not the surrounding somatic cells, is responsible for its failure in postfertilization development. In the present study, we assessed the ability of the XY oocyte to regulate granulosa cell differentiation and functions. Oocyte-cumulus complexes (OCC) were isolated from antral follicles and were cultured in the presence of FSH and testosterone. Microsurgical removal of oocytes prevented cumulus cell expansion and suppressed estradiol production while it promoted progesterone production. Coculture with denuded oocytes from either XX or XY ovaries restored cumulus expansion and the endocrine profile observed in intact OCC. Morphology of oocytes and OCC in the preantral and antral follicles in situ as well as after isolation was compared for XX and XY ovaries. The average area of XY oocytes was smaller by 20% only at the preantral stage, whereas the zona pellucida layer was thinner by 20% at all stages. Furthermore, the XY oocyte was found to be attached to fewer cumulus cells (60% of XX control) in antral follicles and isolated OCC. In conclusion, the XY oocyte develops the normal ability of regulating granulosa cell differentiation despite its inferiority with respect to some morphometric parameters when compared to the XX oocyte.

Animals↗