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Biomedical subjects

A Stevenaert

Publications and source records attributed to A Stevenaert.

At least 73 records · Page 4Linked to original sources
PubMed1990

Pituitary microadenomas: diagnosis with two-and three-dimensional MR imaging at 1.5 T before and after injection of gadolinium.

The usefulness of different magnetic resonance (MR) imaging sequences (coronal and sagittal spin-echo [SE] and three-dimensional fast low-angle shot [3D FLASH]) in the detection of pituitary microadenomas before and after gadolinium injection was prospectively evaluated in 28 patients with surgical confirmation. When evaluated separately, the most useful sequences in the detection of these microadenomas were coronal pregadolinium T1-weighted SE, coronal pregadolinium 3D FLASH, coronal postgadolinium T1-weighted SE, and coronal postgadolinium 3D FLASH. The combination of pre- and postgadolinium T1-weighted sequences with pre-and postgadolinium 3D FLASH sequences produced the highest number of true-positive findings (90%) and the lowest number of false-positive findings (5%). When a 1.5-T imaging unit with a high signal-to-noise ratio allowing useful three-dimensional acquisition is used, the authors advocate a coronal T1-weighted SE sequence, followed (if necessary) by a coronal 3D FLASH sequence, both without injection of gadolinium, in the diagnosis of pituitary microadenomas. When no confident diagnosis is reached, the same sequences should be performed after the injection of gadolinium. The sagittal pre- and postgadolinium T1-weighted SE and long-TR SE sequences are useful only in specific cases.

Adenoma↗
PubMed1990

Placental and pituitary growth hormone secretion during pregnancy in acromegalic women.

It is now well established that during the second half of normal pregnancy, the human placenta secretes its specific GH variant (placental GH) in increasing amounts up to delivery. During the same period, pituitary GH secretion is progressively suppressed. The present study was aimed at clarifying the physiology of GH secretion in pregnant acromegalic women. Two young women remained acromegalic despite transphenoidal removal of their pituitary adenoma. Increased basal levels of GH and insulin-like growth factor-I (IGF-I) as well as paradoxical GH release after TRH injection were noted. Both women became pregnant and delivered term babies without any complication. In both patients, pituitary GH remained elevated during the entire pregnancy, contrary to the situation in normal women. Paradoxical GH release after TRH treatment was also present, whereas no response was observed in five normal control subjects. GH pulsatility studies revealed a highly pulsatile secretory pattern of pituitary GH, in contrast to that in normal woman, whose placental GH is secreted tonically. Tissue placental GH concentrations were within the range of levels in normal placentas. An increase in serum IGF-I in late pregnancy was also similar to that observed in normal pregnancy. These findings confirm that increased IGF-I levels are not pituitary GH dependent in late pregnancy. They add new evidence that adenomatous somatotrophs lack an IGF-I-dependent feedback regulation present in normal somatotrophs.

Acromegaly↗
PubMed1988

Mammosomatotropes in human pituitary adenomas as revealed by electron microscopic double gold immunostaining method.

Hormone production was studied in situ by immunocytochemical methods in 20 pituitary adenomas. Special attention was given to 13 adenomas removed from acromegalic patients. Out of them, 6 had mild to moderate hyperprolactinemia. Immunohistochemistry revealed PRL-containing cells without any close relationship with high PRL serum level in 6 patients. Double immunogold staining revealed mammosomatotrope cells characterized by simultaneous presence of GH and PRL in the same granules in 2 patients. Since mammosomatotropes have never been demonstrated in the normal pituitary, our results probably signify gene dysregulation in pituitary cells of those acromegalic patients.

Adenoma↗
PubMed1986

Study of hypotonic polyuria after trans-sphenoidal pituitary adenomectomy.

We have studied the postoperative diuresis patterns in 116 patients following the removal of a pituitary adenoma using the trans-sphenoidal approach. We observed a normal diuresis (ND) in 55 patients and a hypotonic polyuria (HP) in 61 patients, consisting of water elimination (WE = 45 cases) and transient diabetes insipidus (DI = 16 cases). We investigated the problem of predicting these patterns from eight pre-operative factors by applying stepwise logistic discriminant analysis. We demonstrated that DI was significantly associated with a posterior localization of the adenoma in the pituitary gland and that WE was more frequently observed in cases of suprasellar expansion, in young patients, and in prolactin secreting tumors. Finally, we discuss the pathogenic role of these factors in the occurrence of HP, taking into account inhibition of vasopressin secretion and possible fluid overload.

Adenoma↗
PubMed1986

Early normalization of luteinizing hormone pulsatility after successful transsphenoidal surgery in women with microprolactinomas.

In eight hyperprolactinemic amenorrheic women who had a microprolactinoma, LH secretion was examined by measuring its concentration in blood samples collected every 15 min for 6 h before and 8 days after successful selective adenomectomy. Computer analysis was used for LH peak evaluation. In both circumstances, serum PRL and basal estradiol (E2) levels were also determined. Before operation, the number of LH peaks ranged from zero to one per 6 h in seven patients and was two per 6 h in the eighth patient. In all patients, serum PRL was normal on the eighth postoperative day, while E2 levels remained low, similar to the values usually found in the early follicular phase of the cycle in normal women. Postoperatively, mean LH levels were similar to preoperative levels, but there was a dramatic increase in the number of LH peaks (three to five per 6 h) in five of the eight patients. These observations confirm the impairment of LH pulsatility in hyperprolactinemia and demonstrate that normalization of PRL levels by surgery can restore LH pulsatile secretion in certain women as early as the eighth day after operation in the absence of a significant change in serum E2 levels. Thus, the preoperative impaired pulsatility of LH secretion was probably a central effect of hyperprolactinemia.

Adenoma↗
PubMed1985

Follicle-stimulating hormone-secreting pituitary adenomas.

This retrospective study concerns 40 patients with an apparently nonsecretory pituitary adenoma who were operated on during an 11-yr period from 1971 to 1981. Among them, 6 men had elevated serum FSH levels. LH levels were normal in 5 and slightly elevated in 1. Testosterone levels were low in 2 patients and within normal limits in 2 others. Sexual impotency had developed from 6 months to 1 yr before surgery in all patients. Primary hypogonadism could be eliminated on clinical grounds (recent onset of hypogonadism, previous fertility of 5 of the 6, and postoperative improvement). After transsphenoidal adenomectomy, FSH levels returned to normal values in all, and clinical recovery occurred in most patients. Tumor tissue obtained at operation stained positively for the gonadotropins, but was negative for other pituitary hormones in all patients. The most probable explanation for these findings was that the tumors were responsible for the elevated FSH secretion. This explanation is supported by the immunocytochemical identification of gonadotropin-containing cells in the tumors. We conclude that these 6 men from a series of 40 patients who presented with pituitary tumor but no GH, PRL, or ACTH hypersecretion had primary gonadotropinomas.

Adenoma↗
PubMed1985

[Ultrastructural localization of pituitary hormones by immunocytochemical reactions in ultrathin sections of adenomas].

Human pituitary adenomas were fixed in glutaraldehyde and embedded in epon. Ultrathin sections were incubated either with anti-hGH, anti-hPRL or anti-hLH. They were incubated with second step goat anti-rabbit immunoglobulins linked to gold particles. Two PRL secreting adenomas, one GH and PRL secreting adenoma, one ACTH secreting adenoma and two non secreting adenomas were studied. The specificity and the limits of the method were discussed in relation with the results obtained in light microscopy with the PAP method.

Adenoma↗
PubMed1985

Subacute subdural hematoma as the first symptom in a child with hemophilia A.

The authors reported a case of subacute subdural hematoma in a 14-month-old child suffering from mild hemophilia (Factor VIII, activity: 2.5%). Removal of hematoma under the cover of replacement therapy has been performed safely and has led to recovery without any clinical sequelae. Computerized tomography appeared very useful as an atraumatic method of examination in hemophiliacs. Discussion deals with the problems associated with management of intracranial hemorrhages in hemophiliacs and emphasizes the need of prompt adequate medical and surgical treatment to prevent irreversible damage to the brain.

Brain Damage, Chronic↗
PubMed1984

Two-dimensional echographic localization of intracardiac cerebrospinal fluid shunt catheters.

This study evaluated the ability of two-dimensional echocardiography (2D echo) to detect and localize the distal end of ventriculoatrial shunt catheters in the cardiac chambers of hydrocephalic patients. Twenty-eight patients were studied, and the performances of 2D echo and standard chest x-ray filming were compared. Although standard chest x-ray filming allowed accurate determination of the catheter position in only half of the patients, 2D echo afforded clear visualization and accurate localization of the catheter in all instances. By its precise definition of intracardiac anatomical landmarks and its excellent time determination, 2D echo can provide valuable information on the movements of the catheter's distal end during the cardiac cycle, during head flexion or rotation, and during deep breathing movements. Some interesting observations were made with 2D echo. A to-and-fro motion of the catheter tip through the tricuspid orifice during the cardiac cycle was visualized in two instances. The combination of head movements and deep respiratory movements induced a variation in the position of the catheter tip. The magnitude of this displacement was 6 cm at the most. Two patients underwent reoperation for lengthening or shortening of the catheter. The operative findings confirmed the ultrasonic localization in both cases where the chest x-ray film had failed to identify or adequately locate the catheter tip. It is concluded that 2D echo is a safe, innocuous, and accurate method with which to locate the distal end of a ventriculoatrial shunt. It is the only available technique that provides visualization of intracardiac structures and cardiac cycle reference.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1982

[Practical assessment of brain dysfunction in severe head trauma (author's transl)].

Assessment of brain dysfunction in head injured patients is important as an index of severity of brain damage and forms the basis of monitoring. . The Glasgow Coma scale (G.C.S.) is a practical scale for nurses. The Liege Coma scale contains the three variables of the G.C.S. and provides informations concerning the brain stem reflexes. In a series of 60 head-injured patients, recovery rates were calculated on the basis of either Glasgow scores or Liege scores. The Liege Coma scale provides a more sensitive index of clinical course and a better prognosis.

Adolescent↗