Involvement of ETA and ETB receptors in the activation of phospholipase D by endothelins in cultured rat cortical astrocytes

1. This study was performed to characterize the receptor subtypes involved in the endothelin stimulation of phospholipase D (PLD) in rat cortical astrocytes in primary culture. PLD activity was determined by measuring the formation of [³²P]phosphatidylbutanol in [³²P]orthophosphate prelabelled cells stimulated in the presence of 25 mM butanol.
2. The agonists endothelin-1 (ET-1), endothelin-3 (ET-3), sarafotoxin 6c (S6c) and IRL 1620 elicited PLD activation in a concentration-dependent manner. The potencies of ET-1, ET-3 and S6c were similar. The maximal effects evoked by the ET_B-preferring agonists, ET-3, S6c and IRL 1620, were significantly lower than the maximal response to the non-selective agonist ET-1.
3. The response to 1 nM ET-1 was inhibited by increasing concentrations of the ET_A receptor antagonist BQ-123 in a biphasic manner. A high potency component of the inhibition curve (24.2±3.5% of the ET-1 response) was defined at low (up to 1 μM) concentrations of BQ-123, yielding an estimated K_i value for BQ-123 of 21.3±2.5 nM. In addition, the presence of 1 μM BQ-123 significantly reduced the maximal response to ET-1 but did not change the pD₂ value.
4. Increasing concentrations of the ET_B selective antagonist BQ-788 inhibited the S6c response with a K_i of 17.8±0.8 nM. BQ-788 also inhibited the effect of ET-1, although, in this case, two components were defined, accounting for approximately 50% of the response, and showing K_i values of 20.9±5.1 nM and 439±110 nM, respectively. The ET-1 concentration-response curve was shifted to the right by 1 μM BQ-788, also revealing two components. Only one of them, corresponding to 69.8±4.4% of the response, was sensitive to BQ-788 which showed a K_i value of 28.8±8.9 nM.
5. Rapid desensitization was achieved by preincubation with ET-1 or S6c. In cells pretreated with S6c neither ET-3 nor S6c activated PLD, but ET-1 still induced approximately 40% of the response shown by non-desensitised cells. This remaining response was insensitive to BQ-788, but fully inhibited by BQ-123.
6. In conclusion, endothelins activate PLD in rat cortical astrocytes acting through both ET_A and ET_B receptors, and this response desensitizes rapidly in an apparently homologous fashion. The percentage contribution of ET_A and ET_B receptors to the ET-1 response was found to be approximately 20% and 80%, respectively, when ET_B receptors were not blocked, and 30–50% and 50–70%, respectively, when ET_B receptors were inhibited or desensitized. These results may be relevant to the study of a possible role of PLD in the proliferative effects shown by endothelins on cultured and reactive astrocytes.

     

The prognostic value of progesterone receptor status in meningiomas

BACKGROUND: Meningiomas are known to recur frequently, and their longterm management remains controversial. Previous studies indicate that progesterone and its receptors can play a role in the recurrence of meningiomas, but the correlation between the presence of these receptors and patients' outcome is unclear. AIM: To conduct a retrospective analysis to investigate the prognostic relevance of progesterone receptor (PR) expression in meningiomas. METHODS: Five hundred and eighty eight meningiomas operated on over a period of 10 years were examined immunohistochemically to determine the PR status using monoclonal antibodies. Several factors including recurrence (mean follow up of 65 month), sex, tumour tissue consistency, location, vascularity, and en plaque appearance were analysed. RESULTS: PR status showed comparable values for men and women. World Health Organisation (WHO) grade II and III tumours had significantly fewer receptors than benign meningiomas. There was no significant correlation between PR status and recurrence rates in WHO grade I totally removed meningiomas. However, a combination of PR status and proliferation indices was shown to predict recurrence reliably. CONCLUSIONS: Together with routine histological evaluation, PR status can help to describe the biological behaviour of meningiomas. Only a combination of clinical and biological features can describe the behaviour of meningiomas, predict their recurrence, and help to devise more effective follow up strategies.     

Endocrinology: Midluteal immunoreactive {alpha}-inhibin serum concentrations as markers of luteal phase deficiency

The present prospective clinical study was undertaken to determinethe usefulness of midluteal phase serum immunoreactive -inhibinconcentrations as markers of luteal phase deficiency and whetherthey are better indicators of biopsy confirmed luteal phasedefect than serum progesterone. Consecutive patients (n = 138)with regular menstrual cycles attending our Infertility Clinic(experimental group) and 15 fertile women who were requestingcontraception and had regular menstrual patterns (control group)were included. In all women (patients and controls), basal bodytemperature, midluteal serum concentrations of oestradiol, prolactin,progesterone and immunoreactive -inhibin, and premenstrual endometrialbiopsy were used in the same cycle to assess luteal function.Out-of-phase secretory endometria were detected in 15 of the138 patients. Thus, hormonal concentrations were compared betweenthe following three groups of women: group 1 (n = 15), infertilepatients with defective secretory endometria; group 2 (n = 123),infertile patients with normal secretory endometria; and controls(n = 15), fertile women with normal secretory endometria. Midlutealserum concentrations of progesterone, immunoreactive -inhibin,oestradiol, and prolactin of the two groups studied were similarto those of the control group of fertile women. Our resultsindicate that midluteal serum inhibin determination does notaccurately reflect histological maturation of the endo-metriumand it is not a better indicator of endometrial luteal phasedeficiency than midluteal serum progesterone concentration.     

Sjögren's Syndrome

Sj?gren's syndrome is a systemic autoimmune disease that is characterized by the presence of keratoconjunctivitis sicca, xerostomy and a large spectrum of signs and symptoms that translate into a very heterogeneous disease. The mild form that affects mucosal tissues is the most frequent, but there are more severe and active patterns, manifested by the presence of extraglandular affection with a worse prognosis. The clinical spectrum includes anything from mucosal alterations, Raynaud's phenomenon, parotid enlargement or arthritis, but can be aggravated by the presence of neurological, lung or renal affection. Initial therapy includes topical treatment with artificial tears, nocturnal cream and drugs that stimulate secretion for important glandular affection, while severe systemic affection merits immunosuppressant therapy. There has been recent evidence that biologic therapy is useful for the treatment of severe and resistant cases.     

Human exposure to PBDEs through the diet in Catalonia, Spain: temporal trend. A review of recent literature on dietary PBDE intake

The mean concentrations of polybrominated diphenyl ethers (PBDEs) (sum tetra- to octaBDEs) were determined in samples of foodstuffs widely consumed by the population of Catalonia, Northeast Spain. The following six tetra-through heptabrominated congeners were also individually analyzed: PBDEs 47, 99, 100, 153, 154 and 183. Food samples were randomly acquired in 12 cities of Catalonia between March and June of 2006. The dietary intake of PBDEs was estimated for the population of this region. In order to determine the temporal trend on the exposure to PBDEs through the diet, the results were compared with those of a previous survey performed during 2000. The highest concentration of total PBDEs was found in fish and shellfish (563.9 ng/kg of wet weight), followed by oils and fats (359.3 ng/kg ww), and bakery products (98.8 ng/kg ww). Among six individually analyzed congeners, for most food groups BDE-47 and BDE-99 showed the highest levels. The dietary intake of PBDEs for a standard male adult of 70 kg body weight was 75.4 ng/day (or 1.1 ng/kg body weight/day, assuming ND = LOD/2). On a body weight basis, it means a decrease of 23% with respect to the daily intake of the 2000 survey (97.3 ng/day or 1.4 ng/kg/body weight/day). Finally, the current PBDE intake is compared with the results of recent studies on the dietary intake of PBDEs performed in various European, North American, and Asian countries.