Search PubMed⌕ Search

Biomedical subjects

J Riishede

Publications and source records attributed to J Riishede.

At least 19 recordsLinked to original sources
PubMed2004

Photonic crystal fiber based evanescent-wave sensor for detection of biomolecules in aqueous solutions.

We demonstrate highly efficient evanescent-wave detection of fluorophore-labeled biomolecules in aqueous solutions positioned in the air holes of the microstructured part of a photonic crystal fiber. The air-suspended silica structures located between three neighboring air holes in the cladding crystal guide light with a large fraction of the optical field penetrating into the sample even at wavelengths in the visible range. An effective interaction length of several centimeters is obtained when a sample volume of less than 1 microL is used.

Biocompatible Materials↗
PubMed1984

Plasma vasopressin, cortisol, and growth hormone concentrations in relation to surgery in the suprasellar region.

Posterior and anterior pituitary functions were assessed in 8 patients before, during, and after surgery for tumors in the suprasellar region. Preoperatively, all patients but one responded adequately to an osmotic stimulus with a rise in plasma vasopressin (AVP) and all but one showed adequate cortisol response to adrenocorticotropic hormone (ACTH) and hypoglycemia. During surgery a transient rise was seen in plasma levels of AVP (5 out of 8 patients), cortisol (7 out of 8 patients) and growth hormone (4 out of 8 patients). This response could be predicted from the preoperative stimulation tests. Postoperatively the AVP response to osmotic stimuli was impaired in 4 out of 5 patients, although urine volume had returned to normal after a transient polyuric phase. The response of plasma cortisol to ACTH was still adequate but lower than preoperatively.

Adenoma↗
PubMed1983

Pituitary abscess.

All cases of pituitary abscesses (19 patients) reported in the literature since 1970 are reviewed. Based on the data available, it is suggested that a pituitary abscess is not a bacterial infection as commonly assumed. Probably, it represents a normal tissue reaction to an infarction of a pituitary adenoma. The frequent association with negative cultures from the abscesses, previous sterile meningitis and endocrine disturbances, and concurrent rhinorrhoea are well explained in this way.

Abscess↗
PubMed1983

Pituitary function in patients with evidence of spontaneous disappearance of a pituitary adenoma.

Forty-four untreated patients with an enlarged sella were studied (excluding patients with acromegaly, Cushing's disease, and those with radiological evidence of suprasellar extension). In 20 patients CT revealed a completely or partially empty sella. Based on recent studies we take this finding to signify the previous presence of a pituitary adenoma which has undergone complete or partial necrosis. Ten of the 20 patients had in fact experienced symptoms typical of a pituitary apoplexy compared with only one out of the other 24 patients. Adrenal, thyroid, and growth-hormone insufficiency occurred as often in patients with an empty sella as in those with a solid pituitary tumour. In contrast, plasma prolactin levels were much lower in patients with an empty sella than in patients with a solid tumour (11 vs 166 ng/ml). It is assumed that this discrepancy reflects previous necrosis occurring in an adenoma hypersecreting prolactin. These results emphasize the importance of taking the spontaneous course of pituitary adenomas into account when assessing the effect of various treatment protocols.

Adenoma↗
PubMed1982

The empty sella and pituitary adenomas. A theory on the causal relationship.

In 44 consecutive patients with sellar volume larger than 1100 mm3, computer tomography showed that 20 had an empty or partly empty sella. None had radiological evidence of a suprasellar tumor. 10 of the 20 patients had experienced episodes with acute neurological symptoms presumably reflecting a pituitary apoplexy. It is suggested that an unknown proportion of intrasellar adenomas may disappear as a result of an infarction, which may comprise the entire adenoma or part of it--leaving an empty or partly empty sella as diagnosed by computer tomography. Air encephalography will demonstrate the empty sella only if the diaphragmatic aperture is large enough to allow cisternal herniation. The infarction may present clinically with no, slight or severe acute neurological symptoms. Late consequences of a pituitary adenoma infarction may be rhinorrhea or hydrocephalus.

Adenoma↗
PubMed1981

No effect of bromocriptine in acromegaly: a controlled trial.

Although bromocriptine, a dopamine receptor agonist, is now widely used in the treatment of acromegaly, there have been no controlled trials of its biochemical or clinical effects on this disorder. We assessed its effects in a double-blind, crossover study. Eighteen patients with acromegaly were given bromocriptine and placebo alternately for three months per medication. Their responses to oral glucose-tolerance tests during the two regimens did not differ significantly. The number of patients noting amelioration of clinical symptoms during treatment with bromocriptine was almost identical to the number with clinical improvement during placebo. We conclude that it remains doubtful whether bromocriptine has a beneficial effect in acromegaly.

Acromegaly↗
PubMed1980

Urinary excretion of cortisol in acromegaly.

Free urinary cortisol excretion was measured in 19 patients with acromegaly and 19 matched controls with other pituitary disorders who were comparable with regard to age, sex, and adrenocortical response to ACTH. Excretion of cortisol was significantly higher (P less than 0.01) in the acromegalics (mean, 161 micrograms/24 h or 444 nmol/24 h) compared to the controls (mean, 82 micrograms/24 h or 226 nmol/24 h) normal subjects (mean, 85 micrograms/24 h or 235 nmol/24 h). Seven of the acromegalics had excretion of urinary cortisol exceeding the upper normal limit. The most probable cause is an increased glomerular filtration of cortisol.

Acromegaly↗
PubMed1979

Relationship between plasma prolactin concentration and pituitary function in patients with a pituitary adenoma.

The influence of hyperprolactinaemia on endocrine functions in forty-two consecutive patients with untreated pituitary tumours was studied. Patients with acromegaly, Cushing's disease and Nelson's syndrome were excluded. Sixteen patients (eleven men and five women) had a pituitary adenoma with suprasellar extension and twenty-six (eleven men and fifteen women) had a small intrasellar tumour. Basal plasma prolactin concentration was measured in all. Thyroid function was assessed by plasma thyroxine (T4) and TSH concentrations, adrenocortical function and growth hormone (GH) secretion by the maximum plasma cortisol, adrenocorticotrophin (ACTH) and GH concentrations, respectively, during insulin-induced hypoglycaemia (tITT). Gonadal function was studied by measuring plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), oestradiol-17 beta and in men, testosterone. On the basis of computer assisted tomography of the sella turcica, the tumour volume was calculated. The basal plasma prolactin concentration was elevated in 69% of the patients. Decreased GH secretion was the most frequent pituitary dysfunction (78%) followed in men by gonadal insufficiency (77%), adrenocortical insufficiency (31%) and thyroid insufficiency (21%). There was no difference between patients with elevated and normal plasma prolactin concentration as to the tumour volume and any of the endocrine variables.

Adenoma↗
PubMed1979

Plasma corticotropin and cortisol in patients with pituitary adenomas.

Plasma ACTH and cortisol were measured during insulin-induced hypoglycemia in 39 patients with a pituitary adenoma or after hypophysectomy and in 26 healthy persons. Adrenocortical insufficiency was defined as failure to increase plasma cortisol to at least 500 nmol/liter (18 microgram/dl) during hypoglycemia. No proper distinction was possible between patients with normal and impaired cortisol response to hypoglycemia on the basis of the ACTH results. When all 39 patients were compared to the 26 controls, the cortisol results differed significantly, but those of ACTH did not. These results demonstrate a limited value of ACTH measurements in secondary adrenocortical failure.

Adenoma↗
PubMed1978

Alpha-fetoprotein and human chorionic gonadotropin in a patient with a primary intracranial germ cell tumor.

A 17 year old man with a primary intracranial germ cell tumor in the pituitary region is reported. Both serum alpha-fetoprotein (AFP) and serum human chorionic gonadotropin (hCG) were found elevated preoperatively. Normal levels of serum AFP and hCG were found after operation and radiotherapy. By indirect immunofluorescence staining of the tumor tissue a slight staining for AFP was localized to the endodermal vesicles, whereas a more intensive staining for hCG could be identified in the giant cells.

Adolescent↗
PubMed1978

Pituitary oncocytic tumor with Cushing's disease.

Pituitary adenomas composed of oncocytes are rare. We report a young female with an atypical oncocytic tumor of the pituitary. The histology was unusual because the oncocytic cells--in addition to an abundance of abnormal mitochondria--contained a conspicuous smooth endoplasmic reticulum. The tumor grew invasively and the patient developed adrenal hypercorticism.

Adenoma↗
PubMed1978

Discrepancy between ACTH and cortisol responses to insulin induced hypoglycaemia.

The purpose of this study was to assess the normal relationship between plasma ACTH and cortisol during insulin induced hypoglycaemia. Twenty-six healthy persons were studied. Peak plasma concentration and the amounts of ACTH and cortisol secreted during hypoglycaemia were compared. There was no significant correlation between the ACTH and cortisol values. The ACTH responses varied significantly more than those of cortisol. This probably signifies an over-capacity of ACTH secretion in comparison to the secretory capacity of the adrenal cortex.

Adrenocorticotropic Hormone↗
PubMed1978

Reliability of the 30-minute ACTH test in assessing hypothalamic-pituitary-adrenal function.

An insulin hypoglycemia test and a 30-min ACTH test were performed in 90 patients with proved or suspected hypothalamic-pituitary-adrenal hypofunction and in 10 normal subjects. The peak plasma cortisol concentration during hypoglycemia and the cortisol concentration at 30 min after injection of 250 micrograms corticotropin 1-24 were compared. A very close correlation (r = 0.92) was found between the the two concentrations, with no major discrepancy in any case. It is concluded that the short ACTH test accurately reflects the integrated hypothalamic-pituitary-adrenal function, as assessed by the insulin hypoglycemia test.

Adenoma↗