Biomedical subjects

V Ang

Publications and source records attributed to V Ang.

5 recordsLinked to original sources

PubMed1998

Thermal control of drug release by a responsive ion track membrane observed by radio tracer flow dialysis.

The combination of a responsive hydrogel with a rigid porous supporting structure yield a membrane with high mechanical strength and high on-off-permeability ratio. A membrane consisting of an ion track filter with a thermally responsive lining was prepared by penetrating a 19 micron thick foil of poly(ethylene terephthalate) (PET) with swift heavy ions at a fluence of 5 x 10(5) ions/cm2, followed by etching of the ion tracks to generate an ion track filter with 2.9 micron pore diameter, onto which a thin layer of poly(N-isopropylacrylamide) (NIPAAm) hydrogel was grafted. It was revealed that the mass flow of various molecules (water, chloride-, choline+, insulin, and albumin) through the membrane could be thermally controlled. The on-off-permeability ratio ranged between 3 and 10 increasing with molecular weight. Over a storage time of 5 months the permeabilities varied up to a factor of 2.6, while the on-off-permeability ratio and temperature sensitivity remained practically constant.

Drug Delivery Systems↗

PubMed1981

Vasopressin in plasma and CSF of patients with subarachnoid haemorrhage.

Arginine vasopressin was measured in the blood and cerebrospinal fluid (CSF) of 42 patients with subarachnoid haemorrhage. Increased concentrations of vasopressin were present in 10 patients, of whom eight had bled from an anterior communicating artery aneurysm. In three patients high blood vasopressin values were associated with gross hyponatraemia. Five patients were found to have increased CSF vasopressin concentrations in the presence of normal plasma values and in all of these the level of consciousness was severely disturbed. It is suggested that an increased secretion of vasopressin into the blood or CSF may be a contributory factor in the worsening condition of some patients with subarachnoid haemorrhage.

Adult↗

PubMed1980

Vasopressin in human cerebrospinal fluid.

Arginine vasopressin was measured by RIA in samples of plasma and cerebrospinal fluid (CSF) taken synchronously from 62 patients with proven or suspected disorders of the central nervous system in order to determine the relationship between the secretion of vasopressin into the systemic circulation and that into the CSF. In 12 patients without endocrine or brain disease, mean plasma values (+/- SD) were 2.8 +/- 0.7 pg/ml and CSF values were 2.4 +/- 0.7 pg/ml. Thirty-six patients with various intracranial disorders had plasma and CSF values which were both within the range of 1-4 pg/ml. Eight patients had raised plasma concentrations, but their CSF levels were within the normal range. One patient with posttraumatic diabetes insipidus and 2 patients with subarachnoid hemorrhage had concentrations of CSF vasopressin which were greater than plasma levels. These results indicate that a blood CSF barrier to vasopressin exists in man and that under certain pathological conditions excessive amounts of the hormone can be secreted into the CSF independently of that which is released into the blood, a finding which could have clinical significance in disorders of brain function.

Adolescent↗

PubMed1978

Bromocriptine treatment of males with pituitary tumours, hyperprolactinaemia, and hypogonadism.

Plasma prolactin concentrations were measured in thirty-four males with pituitary tumours and twenty-two patients (65%) were found to have hyperprolactinaemia. Plasma testosterone concentrations were subnormal in twenty-nine patients. Ten patients with hyperprolactinaemia were treated with bromocriptine; prolactin was restored to normal values in eight patients but testosterone secretion remained deficient. Two patients were resistant to bromocriptine. Some improvement in libido and potency was obtained after restoration of normal prolactin concentrations in four cases in spite of persistently low testosterone secretion. For maximal improvement in sexual function treatment with both bromocriptine and testosterone was required.

Bromocriptine↗

PubMed1976

Hypothalamic-pituitary function in patients with craniopharyngiomas.

Hypothalamic-pituitary function was investigated in 20 patients with craniopharyngioma, and all showed some degree of hypopituitarism. Pituitary-adrenal dysfunction was present in 50% of the patients whereas all but one had deficiencies of growth hormone and gonadotropin. Serum thyroxine was low in 13 patients, and in a further six there was an abnormal response of thyrotropin (TSH) to thyrotropin-releasing hormone (TRH). Prolactin levels were normal in over half the patients tested and only moderately elevated in the remainder. Gonadotropins failed to increase adequately after gonadotropin-releasing hormone (LRH) in all but one patient, and the response gave no indication of the predominantly hypothalamic site of the tumors.

Adolescent↗