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N Simionescu

Publications and source records attributed to N Simionescu.

135 records · Page 8Linked to original sources
PubMedDate not supplied

In vitro study of low density lipoprotein--collagen interaction.

Possibility of LDL--collagen complex formation was investigated in vitro by biochemical assay and electron microscopy. Types I and III collagen isolated from bovine thoracic aorta were incubated with human low density lipoproteins (LDL) at physiological ionic strength, pH and temperature. Biochemical quantification showed that 10-20 micrograms LDL (cholesterol) were bound per 100 micrograms collagen, binding of type III being slightly more pronounced (17%) than that of type I (11%). Binding was in inversely proportional to the extent of fibrillation. The increase of ionic strength and pH reduced the binding, indicating the electrostatic nature of the interaction. These observations suggest a possible trapping mechanism of LDL in the extracellular matrix by means of collagen, which may be relevant for the development of the atherosclerotic lesions.

Arteriosclerosis↗
PubMedDate not supplied

Bromocriptine treatment of pituitary adenomas. Evaluation of withdrawal effect.

Forty patients wtih pituitary adenomas, i.e. 22 prolactinomas, 13 acromegalies, 5 non-secreting adenomas, were submitted to bromocriptine therapy 19.3 +/- 1.7 mg/day (mean +/- SEM) (range 7.5-40.0 mg/day) for 5 to 41 months (10.1 +/- 1.31). Remission of the tumoral mass was documented by air tomograms (PETG) or computerized tomograms (CT) in all but one prolactinomas and in 2 mixed HGH and PRL-secreting adenomas. Six empty sella syndromes (ESS) were produced, 4 of them during primary chemotherapy. Serum PRL decreased to normal in all but 3 prolactinomas, and serum HGH levels in 5 out of 13 acromegalies. Bromocriptine withdrawal was followed by a rapid increase of serum PRL into the pathological range, without a rapid reexpansion of the tumoral remnants: GT or surgical exploration of 4 cases, remitted until ESS showed a minimal evolution along 8 months after bromocriptine withdrawal. It is suggested that the antitumoral effect of bromocriptine is specific to lactotrophic cells and at least partially irreversible.

Acromegaly↗
PubMedDate not supplied

Additional antitumoral effects of bromocriptine and radiotherapy in patients with prolactinomas or acromegaly.

Thirteen patients with prolactin-secreting and/or growth hormone secreting pituitary tumours have been treated with bromocriptine in doses of about 10 mg/day for several months. Nine of these patients were previously submitted to external or interstitial radiotherapy and one case to pituitary microsurgery. Serum prolactin concentration in patients with prolactinomas was still very high within one year after pituitary irradiation or operation, i.e. 5,125.6 +/- 974 mU/l (mean +/- SEM). It has been reduced to normal level only during bromocriptine therapy, i.e. to 329.1 +/- 88mU/l (p less than 0.001), and increased thereafter, but remained to a significantly lower concentration than before bromocriptine treatment, i.e. 2,709.0 +/- 553 mU/l (p less than 0.05). Serial pneumonecephalotomography has demonstrated the reduction of tumour size afrer bromcriptine therapy to two prolactinomas with suprasellar extension. In patients with acromegaly the effects of bromocriptine were less evident. The antitumoral effects of bromocriptine on prolactin-secreting adenomas is independent and additional to the effects of pituitary radiotherapy or microsurgery, and has therapeuticical implications.

Acromegaly↗
PubMedDate not supplied

Blood-cerebrospinal fluid barrier for prolactin in empty sella syndrome.

In six patients with "empty sella" syndrome (ESS), three primary (pESS) and three secndary (sESS), the ratio of serum to cerebrospinal fluid (CSF) concentrations of prolactin (PRL) was 6.6 +/- 0.7 (mean +/- SEM) (range 5.5--9.6), with a significant correlation between serum and CSF levels of PRL (r = 0.93 p less than 0.01). A control group of ten normal subjects showed similar values. The hyperprolactinemia found in two cases of pESS did not change the serum/ CSF ratio of PRL. The acute release of PRL into the serum following TRH i.v. did not increase the PRL level in CSF either in control subjects or ESS, with one exception. In a case of sESS consecutive to the treatment with bromocriptine (for 6 months) of an invasive prolactinoma, TRH i. v. released PRL into the CSF but not into the blood, and the serum/ CSF ratio of PRL was very low, until a new cure with bromocriptine (for 3 months) mormalised it. It is suggested that the blood-CSF barrier for PRL is similar in ESS and in normal subjects, with the exception of sESS following incomplete remission of some invasive prolactinomas, in which the high permeability of BCB may be explained both by hemodynamic changes in the pituitary portal vascular system and by a new source of PRL which release it directly into the CSF, bypassing the blood route.

Adolescent↗