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Biomedical subjects

M F Borges

Publications and source records attributed to M F Borges.

10 recordsLinked to original sources
PubMed1999

Diagnostic value of fluorometric assays in the evaluation of precocious puberty.

To establish normative data and determine the value of fluorometric AutoDELFIA assays (Wallac Oy) in the investigation of precocious puberty, we determined serum levels of LH, FSH, testosterone, and estradiol under basal and GnRH-stimulated conditions in 277 normal subjects at various pubertal stages and in 77 patients with precocious puberty. A substantial overlap was observed in basal and GnRH-stimulated gonadotropin levels in normal individuals of both sexes with pubertal Tanner stages 1 and 2. The 95th percentile of the normal prepubertal population was the cut-off limit between prepubertal and pubertal levels. These limits were 0.6 IU/L in both sexes for basal LH, 9.6 IU/L in boys and 6.9 IU/L in girls for peak LH after GnRH stimulation, 19 ng/dL in boys for basal testosterone, and 13.6 pg/mL in girls for basal estradiol. Basal and peak LH exceeding these limits were considered positive tests for the diagnosis of gonadotropin-dependent precocious puberty. According to these criteria, the sensitivities of basal and peak LH for the latter diagnosis were 71.4% and 100% in boys, and 62.7% and 92.2% in girls. The specificity and positive predicted value were 100% in both sexes for basal and peak LH levels. The negative predicted values for basal and peak LH were 62.5% and 100% in boys, and 40.6% and 76.5% in girls. Basal and GnRH-stimulated FSH levels overlapped among the various pubertal stages in normal subjects and were, in general, not helpful in the differential diagnosis of precocious puberty. In conclusion, basal LH levels were sufficient to establish the diagnosis of gonadotropin-dependent precocious puberty in 71.4% of boys and 62.7% of girls. In the remaining patients, a GnRH stimulation test was still necessary to confirm this diagnosis. Finally, suppressed LH and FSH levels after GnRH stimulation indicate gonadotropin-independent sexual steroid production.

Adolescent↗
PubMed1998

Calcitonin deficiency in early stages of chronic autoimmune thyroiditis.

OBJECTIVES: Although calcitonin (Ct) deficiency has been described in chronic autoimmune thyroiditis (CAT) it is unclear at what stage in the disease it develops. We have analysed the Ct secretory responses of patients in two different evolutionary stages of CAT, namely the goitrous and atrophic phases. DESIGN: We studied the Ct response to combined calcium (2 mg/kg) and pentagastrin (0.5 microgram/kg) intravenous infusion in 27 patients with CAT and 30 normal adult controls. The cases were divided into two groups. The first comprised eleven women with CAT and goitrous subclinical hypothyroidism (GH), aged 28.6 +/- 10.1 years--at diagnosis they had increased thyroid autoantibody titres and cytological features compatible with stages 1 and 2 of Hashimoto's thyroiditis. The second comprised 16 females with CAT and an atrophic thyroid confirmed by ultrasound scan, aged 38.0 +/- 9.2 years--these patients were severely hypothyroid at diagnosis and were termed AH (atrophic hypothyroidism). Both groups (GH and AH) received replacement doses of thyroxine sufficient to restore euthyroidism for at least six months before the stimulation tests. Control group (C) consisted of 20 healthy women (A), aged 30.0 +/- 9.6 years, and 10 healthy men (B), aged 34.7 +/- 8.0 years. Serum Ct was measured by IRMA. The Ct secretory response was related to thyroid size and cytological data, when available. RESULTS: Basal Ct concentrations in groups GH (0.08 ng/l, median) and AH (0.07 ng/l, median) were significantly lower than those of female controls (0.58 ng/l, median). Stimulated Ct peak values in groups GH (0.08 ng/l, median) and AH (0.19 ng/l, median) were significantly lower than those of female controls (13.61 ng/l, median). Also, both basal (2.72 ng/l, median) and stimulated Ct levels (35.73 ng/l, median) in male controls were significantly higher than in female controls given already. A positive correlation between the Ct secretory reserve and thyroid dimensions, evaluated by ultrasound scan, was found only in patients with thyroid atrophy (AH; rs = 0.61, P < 0.05). CONCLUSIONS: We have found low basal and stimulated calcitonin values in patients with chronic autoimmune thyroiditis and thyroid enlargement, which represents an early phase of chronic autoimmune thyroiditis. Our data have also confirmed previous findings of deficient calcitonin secretion in advanced stages of chronic autoimmune thyroiditis in which thyroid atrophy is usually found. These findings may be associated with C-cell destruction following progressive, nonspecific follicular cell damage caused by lymphocytic infiltration and fibrosis of the gland.

Adult↗
PubMed1998

Quantitative analysis of C cells in Hashimoto's thyroiditis.

The objective of the present investigation was to study quantitatively C cells in Hashimoto's thyroiditis (HT) by analyzing 22 thyroids obtained at autopsy or thyroidectomy from 16 patients with thyroiditis and from 6 normal subjects. Six different areas were sampled on average and labeled with a monoclonal anticalcitonin antibody by immunohistochemistry using the avidin-biotin-peroxidase complex. Normal thyroids from adult patients with no thyroid disease were used as control. C cells were counted in 1 cm2 fields and the mean number of cells per field was calculated. Data were analyzed statistically by the Mann-Whitney test. The inflammatory process detected in cases of HT was usually moderate (50%) and the number of C cells ranged from 0 to 12.2 per 1 cm2 field. The number of C cells in normal thyroids ranged from 20 to 148 per 1 cm2 field, with a median of 35.2 cells per field. The results demonstrate a significant decrease in C cell number in HT compared with normal thyroids, indicating that the inflammatory process causes destruction of both follicular and C cells, which are replaced by fibrosis.

Calcitonin↗
PubMed1998

Minimally invasive coronary bypass surgery: postoperative pain management using intermittent bupivacaine infiltration.

Minimally invasive direct coronary artery bypass grafting (MIDCAB) is becoming a popular adjunct to standard cardiac bypass surgery in selected patients with accessible single or double vessel disease. However, the limited anterior thoracotomy used to access the heart involves trauma to the muscle tissue during removal of the fourth costal cartilage and a small piece of connected rib, perhaps leading to more severe postoperative pain compared with patients undergoing routine sternotomy. Intrathecal opioids can be used but have limited therapeutic duration and there is concern regarding anticoagulation. We present a case where soft tissue catheters were placed into the depths of the surgical wounds and pain was diminished greatly by intermittent regular infiltration with bupivacaine.

Anesthetics, Local↗
PubMed1993

Serum testosterone fractions in women: normal and abnormal clinical states.

The potential usefulness of determining serum testosterone (T) fractions in women, ie, sex hormone-binding globulin (SHBG)-bound T, albumin-bound T (Alb-T), and free T (FT) fractions, was explored in a variety of clinical situations. Serum T, SHBG, and albumin concentrations were measured by standardized methods and using binding constants of T to SHBG and albumin, we calculated serum T fractions, which agreed remarkably with measured values of SHBG-T and nonbound T. Serum T levels did not change in normal women examined during the follicular and luteal phases of the menstrual cycle, but SHBG levels were elevated in the luteal phase, changing the distribution of T, with increased SHBG-T and less T distributed to other fractions. Women taking oral contraceptives had decreased serum T levels, but use of androgen-like oral contraceptives decreased SHBG levels and T distribution to this binding protein, whereas use of non-androgen-like oral contraceptives increased SHBG levels, resulting in the expected shift of T fractions. Women receiving phenytoin for seizure disorders and women with Graves' disease exhibited increased SHBG levels with concomitant increased SHBG-T and decreased distribution of T to nonbound fractions. Women with hirsutism exhibited decreased SHBG levels irrespective of total serum T levels, and the T/SHBG ratio was elevated in this population. However, of interest were women with morbid obesity (nonhirsute) who had similar low levels of SHBG and T/SHBG ratios that were indistinguishable from those of hirsute women.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Substituted xanthones as selective and reversible monoamine oxidase A (MAO-A) inhibitors.

1,3-Dihydroxy-2-methylxanthone (X1), its 4-chloro and 4-bromo derivatives (X1-Cl and X1-Br), and 1,3-dihydroxy-4-methylxanthone were investigated for their inhibition activities toward MAO. A hyperbolic function was derived to fit the data and to calculate IC50 values. The compounds proved to be reversible and selective inhibitors of MAO-A, with X1 displaying the highest activity (IC50 = 3.7 microM).

Animals↗