Biomedical subjects

M E Fonseca

Publications and source records attributed to M E Fonseca.

At least 19 recordsLinked to original sources

PubMed1999

Upper body obesity and hyperinsulinemia are associated with anovulation.

The objective of this study was to determine the effect of body fat distribution and hyperinsulinemia on the occurrence of ovulation. Fifty-six women (20-35 years old) either with overweight or obesity (body mass index >/=25) were studied. They were classified in two groups according to waist/hip ratio (WHR); one with predominance of adiposity in the upper body segment (n = 29, WHR >0.85) and the other with predominant adiposity in the lower body segment (n = 27, WHR </=0.85). Basal body temperature and serum progesterone were determined in each cycle during 6 months. Serum insulin levels were measured at baseline and 30, 60, 90, 120 and 180 min after a 75-gram oral glucose load. The mean insulin values in response to oral glucose load in patients with upper body segment obesity were significantly higher than those corresponding to women with lower body segment obesity. Furthermore, the ratio between ovulated cycles and all the cycles studied in patients with upper body segment obesity was significantly lower than that observed in patients with lower body segment obesity. Upper body obesity seems to affect the ovulatory process and this may be related to the presence of hyperinsulinemia.

Adipose Tissue↗

PubMed1998

Effect of naloxone on serum prolactin levels in adult male rabbits.

In order to clarify the possible physiological role of endogenous opioid peptides (EOP), we studied the effect of low doses of naloxone (specific opiate antagonist) on plasma prolactin levels in male rabbits. Five groups of five male rabbits each was injected daily between 8-9 a.m., with naloxone 12.5, 25, 50, 100 and 200 microg/kg/day. An additional group of ten animals was injected with saline solution and considered the control group. Blood samples were taken at baseline before naloxone administration and later at 90 min and 1, 2, 4, 7, 10 days after its administration. Samples were also taken 4 days after stopping naloxone administration (day 14). Plasma prolactin levels were measured by RIA. A significant constant decrease in PRL levels was seen with the 12.5 microg at 90 minutes, while with the remaining doses a progressive decrease was recorded throughout the study.

Animals↗

PubMed1998

[Structural characteristics of prolactin, growth hormone and their receptors as determinants of biological actions].

The pituitary hormones prolactin and growth hormone are structurally related. Both hormones exist in the circulation in several molecular forms, differing in aminoacid sequences, posttranslational modifications and fragments produced by proteolytic cleavage. Heterogencity may produce a diversity of inmunological and biological actions. It has been suggested that each of this forms may be a isohormone with a different physiological role. The predominance of one of them in serun could account for the complex and often contradictory actions of the hormones. In addition receptors also have structural homology and so the possibility exist that these hormones share binding affinity to the receptors and can produce endocrinological problems in some special conditions.

Adult↗

PubMed1997

Surface vesicles: a possible function in commensal relations of Bacteroides fragilis.

Surface vesicles (SV) defined by electron microscopy as outer membrane (OM) extrusions were detected in Bacteroides fragilis strains from distinct sources. A partial identity between SV and OM electrophoretic protein profiles, in addition to the microscopic analysis, may suggest the designation of OMSV. Sialidase activity, a virulence determinant, was associated with these sub-cellular structures in all the strains, but in an inverse relation to the vesicle quantity per cell. A commensal strain, previously defined as avirulent in an animal model, presented the lowest vesicle-associated sialidase activity and the greatest SV expression as opposed to what happened with clinical and environmental strains. These results seem to suggest that these surface components have a function in commensal stages of B. fragilis.

Bacterial Outer Membrane Proteins↗

PubMed1997

[The transcendence of prolactin and its relation to the immune response].

Prolactin is a hormone involved in a variety of physiological processes in male and female of several vertebrates species. In mammalian included the human, it has been suggested that prolactin plays a role in immunoregulatory mechanism. There are some evidence in the sense that exists a notable bidirectional interaction between prolactin and the immune systems. This finding has stimulated the research on this area. Prolactin has stimulative effects on the lymphocytes and on the immune responses, and the cytokines production changes the prolactin concentration, so modifying its biological action. These reciprocal effects involve the presence of specific receptors. The prolactin receptors have been demonstrated on lymphocytes and other accessory cells. This review tries to summarize the interaction between immune and neuroendocrine systems and the importance of neuroimmune endocrinologic study.

Female↗

PubMed1997

[The proportion of molecular forms of gonadotropins changes in patients with polycystic ovaries].

It is known that protein hormones circulate as different molecular forms and the relative proportion of these isoforms changes according to endocrine milieu. In particular gonadotropins, both LH and FSH, isoforms suffer variations related to the estrogen levels; thus sera obstained from menopausal women show a predominance of larger molecular forms which are considered as having lesser biological activity and the administration of estrogen replacement therapy is followed by the appearance of intermediate molecular forms possessing higher biological activity. This chormatographic pattern with predominance of intermediate isoforms is typical at midcycle in sera from normal women at the periovulatory stage. Present study showed that sera obtained from anovulatory women, such as patients with polycystic ovaries a predominance of larger and smaller molecular weight isoforms, exhibiting a chromatographic pattern different from that observed in normal women. It is speculate that there is some imbalance between the ovarian steroid synthesis and gonadotropin production in the stage of tertiary structural conformation.

Adult↗

PubMed1997

[Use of metformin in the management of adolescents with polycystic ovary syndrome].

Present study was designed to test that insulin resistance due to hyperinsulinism contribute to the clinical features of polycystic ovarian syndrome (POS). We studied 15 women wit POS who received Metformin 400 mg b.i.d during six months; blood levels of estradiol, testosterone (T), sexual hormone binding globulin (SHBG), insulin like growth factor-I (IGF-I) were determined. In response to treatment women exhibited decrement in serum levels of T as well as an increment, no significative, in both SHBG and IGF-I. Most of the patients showed reduction in body mass index and presented restoration of menstrual cycles. It is concluded that Metformin treatment exerts some metabolic effect which in turn induces some clinical improvement.

Adolescent↗

PubMed1996

A rapid and sensitive dot-blot hybridization assay for the detection of citrus exocortis viroid in Citrus medica with digoxigenin-labelled RNA probes.

A rapid and sensitive dot-blot hybridization assay using in vitro-transcribed digoxigenin-labelled RNA probes (riboprobes) was developed aiming at detection of citrus exocortis viroid (CEVd) in crude sap of infected Citrus medica plants. The protocol includes a very quick and simple preparation of RNA extracts from samples using a denaturation step with formaldehyde. From our results, the employment of this step is highly recommended because the hybridization signals in formaldehyde-denatured samples were significantly stronger when compared with that of extracts without formaldehyde treatment. The assay was found to be sensitive enough to detect 0.1 ng of purified CEVd RNA and was able to detect viroid in 0.2 mg of symptomatic Citrus medica leaves. The use of riboprobes also allowed hybridization under high temperature conditions, avoiding non-specific background.

Digoxigenin↗

PubMed1996

A scanning electron microscopic evaluation of in vitro dentinal tubules penetration by selected anaerobic bacteria.

In vitro root canal dentinal tubule invasion by selected anaerobic bacteria commonly isolated from endodontic infections was evaluated. Dentinal cylinders obtained from bovine incisors were inoculated with bacteria, and microbial penetration into tubules was demonstrated by scanning electron microscopy. The results indicated that all bacterial strains tested were able to penetrate into dentinal tubules, but to different extents.

Actinomyces↗

PubMed1996

Insulin resistance in offspring of hypertensive subjects.

OBJECTIVE: To assess whether apparently healthy subjects with a family history of systemic hypertension have a higher risk of presenting the insulin resistance syndrome. SUBJECTS: Three hundred and eighty-six subjects aged 20-65 years. SETTING: A middle socio-economic class urban community from Mexico City. METHOD: All subjects and, when necessary, their first-degree relatives, answered a questionnaire and underwent a physical examination with measurement of height, weight and blood pressure. Serum insulin, glucose, cholesterol and triglycerides were measured during fasting and 2 h after an oral load of 75 g glucose. RESULTS: A family history of systemic hypertension was present for 167 (43%) of the subjects, of whom 123 (31%) were obese. Subjects with a family history of hypertension had higher systolic blood pressures than did those without such a history (120 +/- 15 versus 115 +/- 10 mmHg). In the logistic regression model, the body mass index and age showed statistically significant effects on the fasting glucose:insulin ratio and on serum insulin levels after an oral load of glucose. When men and women were analysed separately, only in men were higher systolic and mean blood pressures and lower glucose:insulin ratios observed. In the logistic regression analysis the body mass index was a significant predictor of the glucose:insulin ratio and serum insulin levels after an oral load of glucose, especially in men. CONCLUSION: Apparently healthy male offspring of hypertensive parents have higher blood pressure levels and lower insulin sensitivities than do offspring of normotensive parents. Insulin resistance was related to obesity, but not to a family history of hypertension, as had previously been reported by other research groups.

Adult↗

PubMed1996

[Changes in molecular forms of sex hormone binding globulin during menstrual cycle and menopause].

Sex hormone binding globulin (SHBG) is a glycoprotein that transports mainly androgens and estrogens regulating the amount of free and bound hormone which in turn plays a role in the metabolic balance. It is also known that estrogens increase the hepatic production of SHBG which circulates in various molecular forms containing different amounts of sialic acid as the main component of carbohydrates. In the present work we studied physiological variations of molecular forms of SHBG during the normal menstrual cycle and the menopause. During the follicular phase the form 54 KD was the predominant variant, in the periovulatory period was isomers 90 KD, and during the luteal phase corresponded to both 54 and 90 KD. In the menopause dimeric form of 90 KD corresponded to the major proportion and was present a higher molecular forms of 115-135 KD. Following estrogen therapy the chromatographic profile changed as to that observed during the menstrual cycle. Important changes in the proportion of sialic acid were observed in each of the phases of menstrual cycle and following estrogen replacement. And increase in the amount of sialic acid corresponded to higher estrogen concentrations. It is concluded that SHBG concentrations varies during the menstrual cycle according the estrogen levels which in addition regulates the proportion of molecular forms and sialic acid containt.

Adult↗

PubMed1995

Activation-induced CD4+ T cell death by apoptosis in experimental Chagas' disease.

Infection of mice with Trypanosoma cruzi, the causative protozoan agent of human Chagas' disease, leads to immunosuppression of the T cell compartment and to chronic cardiac inflammation which resembles the human infection. Recently, reinduction of programmed cell death by apoptosis in mature T cells has been demonstrated. It has been suggested that mature T cell apoptosis could play a role in immunosuppression caused by virus infection. In this report, we have investigated the occurrence of mature T cell apoptosis in murine experimental Chagas' disease. Infection with T. cruzi metacyclic forms led to a relative accumulation of CD8 T cells over CD4 T cells in the spleens of infected mice. Splenic T cells from T. cruzi-infected donors, but not from control littermates, died in vitro upon stimulation with T cell mitogens Con A and anti-TCR-alpha beta mAb in a dose-dependent fashion. DNA fragmentation into nucleosome-sized bands was detected in the supernatants of CD4+ T cells from infected origin, after stimulation with the T cell mitogen Con A. Upon in vitro stimulation with either anti-TCR-alpha beta or Con A, CD4+ T cells were susceptible to elimination, whereas CD8+ T cells were not. Splenic T cells from infected donors were markedly unresponsive to anti-TCR mAb in proliferative assays and underwent apoptosis in vitro, as assessed by electron microscopy. Apoptosis also occurred in vivo in the course of acute infection, as seen by DNA fragmentation in freshly explanted splenic cells and purified T cell subsets. The data indicate that activation-induced CD4+ T cell death by apoptosis is a prominent feature of experimental infection with T. cruzi, and could play a role in immunosuppression and parasite persistence in infected hosts.

Animals↗

PubMed1994

Detection of avocado sunblotch viroid in chloroplasts of avocado leaves by in situ hybridization.

In situ hybridization experiments were carried out to detect avocado sunblotch viroid (ASBVd) in foliar tissue of avocado, using a digoxigenin-labelled RNA probe complementary to the ASBVd-RNA in sections of aldehyde-fixed, LRGold-embedded leaf samples. Detection of the probe was made through anti-digoxigenin antibody and protein-A colloidal gold (20 nm). Seventy to 80% of the signals came from chloroplast while the cytoplasm and vacuole were labelled with ca. 10% of the gold particles. This is in contrast with the subcellular localization of potato spindle tuber viroid and some other related viroids, which are mainly found in the nucleus.

Chloroplasts↗

PubMed1994

Nucleotide sequence of the original Brazilian isolate of coleus yellow viroid from Solenostemon scutellarioides and infectivity of its complementary DNA.

The complete nucleotide (nt) sequence of the original coleus yellow viroid (CYVd) from Solenostemon scutellarioides, 'Golden Bedder', has been determined. The covalently closed single-stranded CYVd RNA molecule consists of 248 nt residues which assumes a rod-like secondary structure when folded in the model of lowest free energy. The sequence was determined by direct sequencing of RNA and from three overlapping cDNA clones. Comparison of the CYVd sequence with that of Coleus blumei viroid 1 (CbVd 1) from Germany demonstrated that they are closely related. The differences observed in the genome organization of CYVd relative to CbVd 1 were at three sites: position 25 (one U deletion), position 26 (a U was replaced by an A) and position 241 (one A insertion). The first two mutations were detected in one A-rich segment of eight nt (between positions 25 and 34). Northern blot hybridization of partially purified nucleic acids from the leaf tissue of S. scutellarioides 'Frilled Fantasy', inoculated with double-stranded cDNA, demonstrated that this fragment was infectious. These data enable CYVd to be assigned to the viroid class of plant pathogens, based on its biological properties and molecular structure. This work also gives additional support to the present classification system, in which the viroids isolated from S. scutellarioides form a distinct subgroup.

Base Sequence↗

PubMed1994

Changes in the prolactin serum isoforms secreted by a pituitary adenoma associated with therapy.

Variations in serum molecular forms of prolactin (PRL) from an adolescent woman presenting amenorrhea-galactorrhea are reported. Persistent hyperprolactinemia and hypoestrogenism were demonstrated as well as the presence of a pituitary tumor with suprasellar extension. Bromocriptine was given at progressive doses up to 37 mg daily, decreasing the hyperprolactinemia and galactorrhea. After 2 years of treatment the patient noticed symptoms of gastric intolerance, bromocriptine was discontinued and a rebound of hyperprolactinemia was observed. Lisuride was administered instead resulting in a new decrease in PRL serum levels, disappearance of galactorrhea and beginning of regular menses. Serum gel chromatographic analysis was carried out before and during lisuride treatment. The first chromatographic analysis showed a predominance of high molecular weight (approximately 66 KD) PRL, accounting for more than 90% of the immunoreactive PRL. The second chromatography showed the major peak of immunoreactive PRL displaced to the right (molecular weight of 22 KD), which was eluted near the PRL standard. With these chromatographic patterns it is concluded that the pituitary macroprolactinoma secreted different molecular forms of PRL and treatment with lisuride appeared to exert some effect on the PRL molecular size secreted by the pituitary.

Adolescent↗

PubMed1993

Interferon action on Mayaro virus replication.

Treatment of TC7 cells with interferon (IFN) drastically reduced the yield of infectious Mayaro virus under experimental conditions that virus attachment and penetration into the cells were not affected. In IFN-treated cells, synthesis of Mayaro virus proteins was inhibited and cellular protein synthesis was restored. This phenomenon is dependent on IFN concentration and multiplicity of infection. Electron microscopy of these cells revealed normal and anomalous viral particles inside cytoplasmic vacuoles. This suggests that IFN also interferes with Mayaro virus morphogenesis and inhibits the release of virions from cells.

Alphavirus↗

PubMed1993

Echovirus type 19 and herpes simplex type 2 infection in human placenta tissue explants.

1. Light and electron microscopy have been used to characterize echovirus 19 and herpes simplex type 2 infection of human placenta tissue in vitro. Immunofluorescence, autoradiography and virus adsorption were used to determine virus replication in this system. 2. Placental tissue was permissive to echovirus 19. Trophoblast cells were lysed with liberation of mature virions. However, during the 48-h period of observation, few cells were damaged and the trophoblastic structure was maintained. 3. HSV-2 infection in placental tissue was aborted although trophoblastic cells allowed virus adsorption, penetration and uncoating. A characteristic cytopathic effect was observed in infected trophoblastic cells in spite of the abortive infection.

Echovirus Infections↗

PubMed1993

[Determination of gastrin levels in maternal and neonatal serum as well as in amniotic fluid in acute fetal distress].

The objective was to measure gastrin (G) levels in maternal and neonatal sera as well as in amniotic fluid in patients with fetal distress and a control group. Twenty-five patients with term pregnancies were assigned to the following two groups: fifteen with acute fetal distress and ten with previous cesarean section. Maternal and neonatal blood and amniotic fluid samples were taken at the time of delivery. Differences between groups were calculated with non-parametric Mann Whitneys' U test. A significant difference (p < 0.001) between G levels in amniotic fluid of fetal distress and those of the control group was found. In conclusion, serum G levels can be used as another predictor of fetal distress, although further studies must be performed before it can be used as a clinical tool.

Acute Disease↗