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Biomedical subjects

C Oliveira

Publications and source records attributed to C Oliveira.

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

Unusual occurrence of a ZZ/ZW sex-chromosome system and supernumerary chromosomes in Characidium cf. fasciatum (Pisces, Characiformes, Characidiinae).

Individuals of two populations of the fish Characidium cf. fasciatum were cytogenetically studied and showed a basic diploid number of 50 chromosomes. Some fishes were found to have 51 to 54 chromosomes due to the presence of one to four small subtelocentric/acrocentric supernumerary chromosomes. When analyzed by conventional Giemsa staining, male and female specimens of C. cf. fasciatum from the Quinta stream and Pardo River presented the same basic karyotypic macro- and microstructure, consisting of 32 metacentric and 18 submetacentric chromosomes. Ag-NORs were terminally located on the long arms of two submetacentric chromosome pairs. Constitutive heterochromatin was identified by C-banding as small pericentromeric blocks in the majority of the chromosomes, and B-chromosomes were found to be heterochromatic. The occurrence of one totally heterochromatic submetacentric chromosome restricted to females and considered as an unusual feature in fish karyotypes led to the identification of a ZZ/ZW sex-chromosome system. The implications of chromosomic differentiation observed in the genus Characidium are discussed.

Journal Article↗
PubMed1998

Molecular cytogenetic analysis of heterochromatin in the chromosomes of tilapia, Oreochromis niloticus (Teleostei: Cichlidae).

The structure of the heterochromatic bands in mitotic chromosomes of the important tropical aquaculture species of tilapia, Oreochromis niloticus, was investigated by the combination of the C-banding technique, chromosomal digestion with two restriction endonucleases and fluorescence in situ hybridization (FISH) of two satellite DNAs (SATA and SATB). The tilapia chromosomes presented heterochromatic bands in the centromeres and in the short arms of almost all chromosomes that were differentially digested by the restriction endonucleases HaeIII and EcoRI. FISH of SATA showed that this satellite sequence is distributed in the centromeric region of all chromosomes of tilapia. FISH also revealed an intense hybridization signal for SATB in only one chromosome pair, but less intense signals were also present in several other pairs. The digestion of tilapia chromosomes by HaeIII and EcoRI was positively correlated with the position of SATA and SATB in chromosomes as revealed by FISH. The results obtained may be useful in future molecular and genetic studies of tilapias.

Animals↗
PubMed1998

Iron supplementation in haemodialysis--practical clinical guidelines.

BACKGROUND: The aim of this prospective study was to test a new protocol for iron supplementation in haemodialysis patients, as well as to assess the utility of different iron metabolism markers in common use and their 'target' values for the correction of iron deficiency. METHODS: Thirty-three of 56 chronic haemodialysis patients were selected for long-term (6 months) i.v. iron therapy at 20 mg three times per week post-dialysis based on the presence of at least one of the following iron metabolism markers: percentage of transferrin saturation (%TSAT) <20%; percentage of hypochromic erythrocytes (%HypoE) > 10% and serum ferritin (SF) <400 microg/l. Reasons for patient exclusion were active inflammatory or infectious diseases, haematological diseases, psychosis, probable iron overload (SF > or =400 microg/l) and/or acute need of blood transfusion mostly due to haemorrhage and change in renal replacement treatment. RESULTS: More than half (51.8%) of the patients of our dialysis centre proved to have some degree of iron deficiency in spite of their regular oral iron supplementation. At the start of the study the mean haemoglobin was 10.8 g/dl and increased after the 6 months of iron treatment to 12.8 g/dl (P<0.0001). The use of erythropoietin decreased from 118 units/kg/week to 84 units/kg/week. The criterion for iron supplementation with the best sensitivity/specificity relationship (100/87.9%) was ferritin <400 microg/l. Patients with ferritin < 100 [microg/l and those with ferritin between 100 microg/l and 400 microg/l had the same increase in haemoglobin but other parameters of iron metabolism were different between the two groups. CONCLUSIONS: Routine supplementation of iron in haemodialysis patients should be performed intravenously. Target ferritin values should be considered individually and the best mean haemoglobin values were achieved at 6 months with a mean ferritin of 456 microg/l (variation from to 919 microg/l). The percentage of transferrin saturation, percentage of hypochromic erythrocytes and ferritin <100 microg/l, were not considered useful parameters to monitor routine iron supplementation in haemodialysis patients. No significant adverse reactions to iron therapy were observed.

Anemia, Iron-Deficiency↗
PubMed1998

The use of bovine pericardium for pulmonary valve reconstruction or conduit replacement: long-term clinical follow up.

BACKGROUND AND AIMS OF THE STUDY: This study aimed to determine the clinical performance of bovine pericardial aldehyde-treated material alone or in combination with aortic leaflets of porcine origin. These were the porcine aortic stentless pulmonary valved bovine pericardial conduit (PSPVC), and porcine aortic monocusp attached to pericardial patch (PAMC), used to correct right-sided heart lesions. METHODS: Between November 1985 and October 1995, 33 patients underwent corrective congenital surgery with PSPVC. Mean patient age was 5.7+/-4.3 years (range: 15 days to 18 years). Pulmonary atresia with ventricular septal defect (VSD) was the most frequent disease (16/33, 48%). For PAMC, 45 patients with various congenital heart malformations underwent implantation between June 1989 and April 1996. Mean patient age was 4.8+/-4.7 years (range: 2 weeks to 18 years). RESULTS: With PSPVC, hospital mortality rate was 18.2% and related to poor preoperative clinical condition in six cases. Four patients were lost to follow up; 23 (85%) were followed for 3 months to 10 years (mean 4.8+/-3.0 years). Distal anastomotic scarring in four patients was probably due to retraction of the pericardial tissue. With PAMC, hospital mortality rate was 11% and related to patients' preoperative clinical condition. Three patients were lost to follow up; 37 survivors have been followed for 6 to 88 months (mean 38.5+/-19.0 months). There were no late deaths. Two patients underwent reoperation; intra-operative observation showed well-preserved monocusps with no signs of tissue degeneration. The remaining 35 patients remain asymptomatic by clinical examination and Doppler echocardiography. The monocusps remained mobile in every case. CONCLUSION: PSPVCs have shown excellent performance and durability in young patients with a low mean age (5 years). The monocusp graft has remained functional with good leaflet motion for up to seven years.

Adolescent↗
PubMed1998

Use of bovine pericardial tissue for aortic valve and aortic root replacement: long-term results.

BACKGROUND AND AIMS OF THE STUDY: The study aimed to determine the clinical performance of bovine pericardial aldehyde-treated products alone or in combination with aortic leaflets of porcine origin. These included a composite porcine stentless aortic valve attached to a scalloped pericardial tube (BSAV), and valved and non-valved bovine pericardial conduits for use in left-sided heart lesions (BPG). METHODS: For BSAV grafts, between January 1990 and August 1996, 163 patients (119 males) had their aortic valves replaced by SJM Biocor BASV. Mean age was 37.9 +/- 17.6 years (range: 1 to 76 years). Rheumatic heart disease sequelae (n = 72) and replacement of a prosthetic heart valve (n = 46) were predominant. Preoperative NYHA functional class showed 90 patients (55.2%) in class III and 50 (30.7%) in class IV. BPVC and NVPC grafts were used in 166 patients: acute aortic dissection was the main indication in 52 (31.3%) and chronic in 36 (21/7%). The ascending aorta was involved in 141 patients (84.9%); grafts were seldom used at other sites. In most patients the graft implanted was either a non-valved (n = 79) or a valved (n = 75) pericardial conduit. Twelve patients had a localized lesion and required a patch repair. RESULTS: For BASV grafts, the non-valve-related hospital mortality rate was 4.9%. There were 14.7% non-fatal complications with full recovery of all patients. Mean follow up in 141 patients was 3.0 +/- 1.4 years (range: 1 month to 7.2 years); 14 patients were lost to follow up. Late, non-conduit-related, mortality occurred in seven patients (4.9%). Eight patients underwent reoperation. The current clinical follow up of 127 patients has shown 118 (92.9%) with competent valves and nine (7.0%) with mild stable aortic insufficiency. For BPVC and NVPC grafts, hospital mortality rate was 16.9%, death being related to poor preoperative clinical condition. Postoperative follow up was accomplished in 125 patients; reoperation was necessary in seven patients. Histology showed good tissue preservation up to five years; echocardiography revealed satisfactory findings. No valved conduit had to be reoperated for valve or pericardial tissue wear. CONCLUSIONS: Clinical results of left-sided heterologous pericardial grafts have shown excellent performance over time. The BASV (over seven years) and BPVC and NVPC (eight years) have demonstrated superior results as aortic valves alone or in combination with a pericardial conduit.

Adolescent↗
PubMed1998

Serologic profile of some sexually transmitted diseases in women with squamous intraepithelial lesions.

UNLABELLED: The purpose of this study consisted of the evaluation of some sexually transmitted diseases in patients with cervical pathology, namely squamous intraepithelial lesions. METHODS: a prospective study was performed. Patients with an abnormal cervical smear were submitted to colposcopy, directed biopsy and an immunologic assay for Chlamydia, Herpes Simplex Virus (HSV) types 1 and 2, Cytomegalovirus, Treponema pallidum, Hepatitis B and Human Immunodeficiency Virus I and II. The same parameters were evaluated in women with normal cervical cytology in a matched control group. A comparative study was performed evaluating some epidemiological parameters and the referred immunologic assays. RESULTS: 118 patients were separated into four groups. Statistically significant differences were observed in the personal history of fungi infections, as well as Chlamydia and HSV 2 IgM. CONCLUSION: immunologic assays may prove useful in identifying sexually-transmitted diseases, especially Chlamydia and HSV 2 infections, in Human Papillomavirus infected women.

Adult↗
PubMed1997

Pregnancy and birth after intracytoplasmic sperm injection with totally immotile sperm recovered from the ejaculate.

OBJECTIVE: To report the birth of two healthy children after intracytoplasmic sperm injection (ICSI) with totally immotile spermatozoa recovered from the ejaculate. DESIGN: Retrospective case report. SETTING: University-based hospital. PATIENT(S): Four couples in whom spermatozoa recovered from the ejaculate were totally immotile but presented normal vitality scores. INTERVENTION(S): Therapeutical IVF-ET attempts coupled with ICSI. MAIN OUTCOME MEASURE(S): Fertilization and pregnancy results after ICSI. RESULTS: With random sperm injection, 19 of the 36 injected oocytes showed normal fertilization and cleavage. One of four patients had a twin pregnancy that resulted in birth of two healthy children. CONCLUSION(S): In cases in which totally immotile ejaculated sperm present normal vitality scores, normal clinical outcomes can be achieved by using the usual random sperm selection during conventional ICSI.

Abortion, Spontaneous↗
PubMed1996

Contribution of plasma membrane and endoplasmic reticulum Ca(2+)-ATPases to the synaptosomal [Ca2+]i increase during oxidative stress.

In the present study we analyzed the effect of ascorbate (0.8 mM)/Fe2+ (2.5 microM)-induced membrane lipid peroxidation on the levels of intracellular free calcium,[Ca2+]i and on the possible mechanisms involved in the perturbation of intracellular calcium homeostasis during oxidative stress. For this purpose, the influence of the ascorbate/iron oxidant system on the plasma membrane and endoplasmic reticulum Ca(2+)-dependent ATPases of brain cortical synaptosomes was studied. In addition, the influence of the peroxidative process on the uptake of calcium (45Ca2+) and on the Na+/Ca2+ exchange activity at the plasma membrane was evaluated. After ascorbate/Fe(2+)-induced membrane lipid peroxidation of the order of 18.05 +/- 4.20 nmol TBARS/mg protein, an increase in [Ca2+]i occurred, under basal or depolarizing conditions (30 mM KCl), which was dependent on the extracellular calcium concentration. Thus, for 1 and 3 mM extracellular calcium concentration, an increase of the resting [Ca2+]i values of 19.8% and 33.7% was observed, while after the K(+)-depolarization the enhancement of the [Ca2+]i was 18.4% and 29.5%, respectively. The Na+/Ca2+ exchange activity and the time-dependent influx of 45Ca2+ observed in basal conditions and after the 30 mM K(+)-depolarization, were not affected under the peroxidative conditions. The Ca(2+)-dependent ATPase activity of the synaptosomal plasma membrane was significantly depressed following peroxidation of membrane lipids, decreasing the V(max) by 48.1%, without significant changes in the affinity of the enzyme for calcium (K(m) for Ca2+ was 0.54 +/- 0.04 microM in control conditions and 0.56 +/- 0.034 microM in peroxidized conditions). The Ca(2+)-ATPase activity of the endoplasmic reticulum was also affected during ascorbate/iron-induced oxidative stress; thus, an inhibition of 45.2% was observed 5 min after adding ATP. These data suggest that the increase in synaptosomal [Ca2+]i due to oxidative stress may result from the inhibition of the plasma membrane and the endoplasmic reticulum membrane Ca(2+)-ATPase activities, probably as a result of the alteration of the lipid environment required for the maximal activity of these membrane enzymes. The consequent increase in [Ca2+]i may be responsible for the injury of the nervous tissue observed during several pathological conditions in which free radical generation seems to be involved.

Adenosine Triphosphatases↗
PubMed1995

Synaptonemal complex analysis in spermatocytes and oocytes of rainbow trout, Oncorhynchus mykiss (Pisces, Salmonidae): the process of autosome and sex chromosome synapsis.

The surface-spreading synaptonemal complex (SC) technique was employed to analyze spermatocytes and oocytes of rainbow trout in order to visualize the process of autosome and sex chromosome synapsis in this species. The structure of lateral elements (LEs) of the SC and the chromosome synapsis process at the stages of leptotene, zygotene and pachytene are described. Comparative analysis of SCs of spermatocytes and oocytes showed a difference in the synaptic process, i.e. in spermatocytes all LEs were synapsed before the appearance of centromeric regions in the biarmed elements, while in the oocytes some fully synapsed LEs, including the centromeric region of the biarmed elements, were found together with fully or partially unsynapsed LEs. In males the sex chromosome synapsis starts only after all autosomes have synapsed. Irregular synapses involving three or four LEs were found in 3.4% of the cells analyzed in mid or late zygotene. Multivalents were found in males and females. Some aspects of initial meiotic development and their implications in rainbow trout cytogenetics, genetics and evolution are discussed.

Animals↗
PubMed1995

Inter-observer agreement in analysis of basal body temperature graphs from infertile women.

In this study, we evaluated the reproducibility of analysis of basal body temperature graphs under optimized conditions for agreement. A total of 160 recordings were selected from spontaneous cycles of infertile women and analysed by three experienced clinicians using uniform criteria. Agreement at the various stages of analysis was assessed by the 'proportions of agreement' with 95% confidence intervals. Agreement in identification of the thermal nadir was clearly superior to that reported in previous publications. Reproducibility of 'ovulatory' graph features (i.e. biphasic graphs and adequate thermal shifts) was excellent. Agreement in classification of monophasic graphs and inadequate thermal shifts, although lower, was still good. Thus, with experienced observers and uniform criteria, a good agreement can be achieved in analysis of the most important parameters of the basal body temperature graph. We believe that an effort should be made to generalize the use of uniform analysis criteria, because only then can results from different institutions be compared and the remaining clinical evaluation of the method be performed.

Basal Metabolism↗
PubMed1995

[Hospital prevalence of kidney failure. Consequences and reflections for the planning of nephrology services].

A prospective prevalence study of Renal Failure (RF) in inhospital patients (creatinine > = 1.7 mg/dl) was carried out during March 1994, in two hospitals covering well defined and mutually exclusive populations. Cases were selected by screening all urea and creatinine blood tests performed in both laboratories, and registered in an individual form for daily follow-up of their nephrologic outcome. We registered 242 RF cases among 3525 patients admitted (6.8%), with an A.R.F. prevalence of 5.2%, 46% of all patients had a serum creatinine > 3 mg/dl and 71% were older than 65 years. In 55% RF was acquired inside the hospital. The most frequent cause of A.R.F. was pre-renal failure with 37%, followed by 32% of ischemic acute tubular necrosis and 13% toxic ATN. Nephrology was consulted in only 29% of all hospital RF cases. Only 17% of the RF patients were submitted to dialysis procedures, overall mortality was 31%, and 30% had normal renal function at discharge. Our results provide a data base to rethink the organization, staffing and role of nephrology departments inside general hospitals.

Female↗
PubMed1994

Persistence of antibodies to hepatitis C virus in a chronic hemodialysis population.

In order to evaluate the persistence of antibodies against hepatitis C virus (HCV) in a chronic hemodialysis population, we studied 151 HBsAg-negative patients. Anti-HCV titers were evaluated every 3 months over 1 year, and the serum alanine aminotransferase/serum aspartate aminotransferase ratio monthly from the start of hemodialysis. The anti-HCV titers (ELISA C100-3) remained stable in 127 patients and fluctuated in 24, without an evident correlation with hepatic function. Using our criteria, we found 85 patients with non-A, non-B hepatitis, 57 of them with biochemical criteria of chronic hepatic disease. There was a strong correlation between antibodies to HCV and non-A, non-B hepatitis (chi 2; p < 0.05) which was more marked in those patients with biochemical criteria of chronic hepatic disease (chi 2; p < 0.001). We concluded that the anti-HCV titer is reliable as a long-term marker of hepatitis C virus infection.

Alanine Transaminase↗
PubMed1994

[Hemodialysis with bicarbonate 30 mEq/l versus 34 mEq/l and acetate: better hemodynamic tolerance and electrolyte and acid-base homeostasis].

The use of bicarbonate buffer in dialysis is more physiological than acetate. The aim of this prospective study was to compare the hemodynamic stability, acid-base and electrolyte balance changes in a group of 5 hospital hemodialysis (HD) patients, with 3 different dialysis fluids: one with 30 mEq/l of bicarbonate (B30), another with 34 mEq/l of bicarbonate (B34) and the last with acetate (ACE). All the patients had more than 12 months in HD. Each patient had HD treatment with one of the 3 different dialysis fluids: ACE, B30, B34. Each HD had a duration of 4 hours, with less than 5% dry weight ultrafiltration (UF) and continuous cardiac monitoring. The following clinical and laboratory data were evaluated: arterial blood pressure (BP), cardiac rate (CR), respiratory rate (RR), cardiac arrhythmias, blood urea, creatinine, sodium, potassium, magnesium, total calcium (Ca), ionised calcium (Ca++), pH, bicarbonate (HCO3-) and pCO2. Statistic analysis was performed using Student's paired t test and ANOVA with Bonferroni correction. Clinical evaluation showed a CR increase only in the ACE group (pre X = 78.4 to 4 degrees h X = 102.6 p < 0.001). Analytical results demonstrated, at the 1st h, Ca++ stability in the B30 group; in the first 30' the pH decreased in the ACE group (pre X = 7.35 to 30' X = 7.34); during HD, HCO3- was not corrected in the ACE group (pre X = 19.4 to 4th h X = 20.0); at 4th, pCO2 also decreased in this group (pre X = 34.5 to 4th h X = 28.4 p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1993

A study of the electrochemical oxidation of Navelbine.

The search for drugs with cytostatic activity and with better pharmacokinetic features led to the synthesis of Navelbine (5'-noranhydrovinblastine) which is a structural modification of antitumour Vinca alkaloids. The new drug Navelbine has high liposolubility, a lower toxicity and increased antitumour activity. The electrochemical oxidation of Navelbine was studied over a wide pH range (1.2-12.8) at a glassy carbon disc electrode in buffered aqueous media using differential pulse and cyclic voltammetry. The anodic oxidation mechanism is a very complex, pH dependent, multistep electron transfer process with coupled homogeneous chemical reactions.

Antineoplastic Agents↗
PubMed1993

Glutamate dehydrogenase deficiency in Machado-Joseph disease.

We studied the activity of glutamate dehydrogenase (GDH) in leukocytes from 23 patients with dominantly inherited ataxia. All the patients were assessed with a rating scale for ataxias and met the clinical criteria for the diagnosis of Machado-Joseph disease. The mean age of onset of symptoms was 37.8, SD 13.4 years and the duration of the disease was 7.4, SD 4.9. Leukocyte GDH activity was significantly decreased (p < 0.001) when compared to 20 normal controls. These data extend previous reports indicating that a GDH deficiency is present in peripheral tissues from some patients with spinocerebellar degenerations. Furthermore, this study suggests that a genetic deficiency of GDH may underlie some forms of dominant ataxias; this deficiency may be marked in patients with Machado-Joseph disease and is not specific for any type of multiple system atrophy.

Adolescent↗
PubMed1993

Chromosome studies in hypoptopomatinae (Pisces, Siluriformes, Loricariidae). II. ZZ/ZW sex-chromosome system, B chromosomes, and constitutive heterochromatin differentiation in Microlepidogaster leucofrenatus.

Cytogenetic analysis of two local populations of Microlepidogaster leucofrenatus showed a basic diploid chromosome number (2N) of 54 in both populations. Some fishes were found to have a 2N = 55 or 56 chromosomes due to the presence of one or two large heterochromatic B chromosomes. Specimens of M. leucofrenatus from the Poço Grande stream had 24 metacentrics, 24 submetacentrics, four subtelocentrics, and one submetacentric homomorphic pair in males and one submetacentric/subtelocentric heteromorphic pair in females, whereas individuals of this species from the Marumbi River had 22 metacentrics, 24 submetacentrics, four subtelocentrics, two acrocentrics, and one submetacentric/subtelocentric heteromorphic pair in females. The occurrence of the heteromorphic pair in the females was due to the presence of an extra C-banded segment on the W chromosome. Ag-NORs in both populations were located interstitially on the short arm of the largest metacentric pair. The Poço Grande population had less constitutive heterochromatin than did the Marumbi River population. The speciation process in this fish species is discussed on the basis of heterochromatin distribution.

Aneuploidy↗