Vitamin D inhibits growth of human airway smooth muscle cells through growth factor-induced phosphorylation of retinoblastoma protein and checkpoint kinase 1

Background and purpose:

Airway remodelling in asthma is manifested, in part, as increased airway smooth muscle (ASM) mass, reflecting myocyte proliferation. We hypothesized that calcitriol, a secosteroidal vitamin D receptor (VDR) modulator, would inhibit growth factor-induced myocyte proliferation.

Experimental approach:

Human ASM cell cultures were derived from bronchial samples taken during surgery. ASM cells were treated with platelet-derived growth factor (PDGF) (10 ng·mL⁻¹) for 24 h in the presence of calcitriol, dexamethasone or a checkpoint kinase 1 (Chk1) inhibitor (SB218078). The effects of calcitriol on PDGF-mediated cell proliferation were assessed by thymidine incorporation assay, propidium iodide-based cell cycle analysis, caspase-3 assay and immunoblotting for specific cell cycle modulators.

Key results:

Calcitriol, but not dexamethasone, inhibited PDGF-induced ASM DNA synthesis concentration dependently (IC₅₀= 520 ± 52 nM). These effects were associated with VDR-mediated expression of cytochrome CYP24A1 with no effects on ASM apoptosis. Calcitriol substantially inhibited (P < 0.01) PDGF-stimulated cell growth in ASM derived from both normal (59 ± 8%) and asthmatic subjects (57 ± 9%). Calcitriol inhibited PDGF-induced phosphorylation of retinoblastoma protein (Rb) and Chk1, with no effects on PDGF-mediated activation of extracellular signal-regulated kinases 1/2, PI3-kinase and S6 kinase, or expression of p21^Waf/Cip-1, p27^Kip1, cyclin D and E2F-1. Consistent with these observations, SB218078 also inhibited (IC₅₀= 450 ± 100 pM) PDGF-induced cell cycle progression.

Conclusions and implications:

Calcitriol decreased PDGF-induced ASM cell growth by inhibiting Rb and Chk1 phosphorylation.This Research Paper is the subject of a Commentary in this issue by Clifford and Knox (pp. 1426–1428). To view this article visit http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009     

Spontaneous release of acetylcholine from autonomic nerves in the bladder

Background and purpose:

Bladder contractility is regulated by intrinsic myogenic mechanisms interacting with autonomic nerves. In this study, we have investigated the physiological role of spontaneous release of acetylcholine in guinea pig and rat bladders.

Experimental approach:

Conventional isotonic or pressure transducers were used to record contractile activity of guinea pig and rat bladders.

Key results:

Hyoscine (3 µmol·L⁻¹), but not tetrodotoxin (TTX, 1 µmol·L⁻¹), reduced basal tension, distension-evoked contractile activity and physostigmine (1 µmol·L⁻¹)-evoked contractions of the whole guinea pig bladder and muscle strips in vitro. ω-Conotoxin GVIA (0.3 µmol·L⁻¹) did not affect physostigmine-induced contractions when given either alone or in combination with ω-agatoxin IVA (0.1 µmol·L⁻¹) and SNX 482 (0.3 µmol·L⁻¹). After 5 days in organotypic culture, when extrinsic nerves had significantly degenerated, the ability of physostigmine to induce contractions was reduced in the dorso-medial strips, but not in lateral strips (which have around 15 times more intramural neurones). Most muscle strips from adult rats lacked intramural neurones. After 5 days in culture, physostigmine-induced or electrical field stimulation-induced contractions of the rat bladder strips were greatly reduced. In anaesthetized rats, topical application of physostigmine (5–500 nmol) on the bladder produced a TTX-resistant tonic contraction that was abolished by atropine (4.4 µmol·kg⁻¹ i.v.).

Conclusions and implications:

The data indicate that there is spontaneous TTX-resistant release of acetylcholine from autonomic cholinergic extrinsic and intrinsic nerves, which significantly affects bladder contractility. This release is resistant to blockade of N, P/Q and R type Ca²⁺ channels.British Journal of Pharmacology (2009) 157, 607–619; doi:10.1111/j.1476-5381.2009.00166.x; published online 3 April 2009     

Patient discomfort during screen-film mammography

Vigorous compression is required to minimize radiation dose and maximize image quality for screen-film mammography. Of 356 women who adequately completed a questionnaire following mammography, 171 (48%) reported mammography to be comfortable, 135 (38%) uncomfortable but tolerable, 39 (11%) very uncomfortable, and only 11 (3%) found the examination to be intolerable. Only 14 women (4%) indicated that they would not return for mammography at our facility in the future. Because of this high level of acceptance of compression by women, technologists and radiologists should not hesitate to use vigorous compression to optimize image quality and decrease radiation dose to the patient.     

Percutaneous vascular intervention after surgical shunting for portal hypertension

Twenty percutaneous transluminal angioplasty (PTA) procedures and 13 percutaneous venous embolization (PVE) procedures were performed in 23 patients who either had or were at risk for the development of recurrent bleeding, hepatic encephalopathy, or both after surgical shunt placement for portal hypertension. PTA, performed in 12 patients with significant shunt stenoses, resulted in reduction or elimination of gradients in all patients; rebleeding has occurred in only one patient. Complications consisted of one fatal rupture of a mesocaval interposition vein graft and one balloon rupture requiring surgical removal. PVE, performed in 11 patients, resulted in measurable improvement in four of seven encephalopathic patients and temporary control in the two patients with intractable bleeding. Three patients underwent PVE prophylactically. PTA of graft strictures is a valuable treatment modality. Embolization may be helpful in selected cases of hepatic encephalopathy.     

Diurnal intraocular pressure reduction with latanoprost 0.005% compared to timolol maleate 0.5% as monotherapy in subjects with exfoliation glaucoma

AIMS: To compare the diurnal intraocular pressure (IOP) efficacy and safety of timolol vs latanoprost in subjects with exfoliation glaucoma (XFG). METHODS: A 3-month prospective, single-masked, active-controlled, parallel comparison performed in six centres in Greece that randomized subjects in a 1 : 1 ratio to either latanoprost in the evening (2000 hours) and placebo in the morning (0800 hours), or timolol twice daily (0800 and 2000 hours). RESULTS: In all, 103 subjects completed the study. After 3 months of chronic dosing, the latanoprost group exhibited a trend to a greater diurnal IOP reduction from an untreated baseline (24.9+/-3.2-17.4+/-2.9) compared with timolol (24.7+/-2.8-18.3+/-1.9 mmHg) (P=0.07). Latanoprost showed a significantly greater IOP reduction at 0800 hours (-8.5 vs -6.0 mm Hg for timolol, P<0.0001) whereas no difference was observed between the two medications at 1000, 1400, and 2000 hours after a Bonferroni Correction. In addition, latanoprost demonstrated a narrower range of diurnal IOP (2.4) than timolol (3.2 mmHg)(P=0.0017). Safety was similar between groups, except there was more conjunctival hyperaemia with latanoprost (n=8) than timolol (n=1)(P=0.01). CONCLUSIONS: This study suggests that latanoprost provides a statistically lower 08:00-hour IOP and better range of IOP than timolol in the treatment of XFG glaucoma.     

SUBTOTAL THYROIDECTOMY IN THE MANAGEMENT OF GRAVE'S DISEASE

Treatment options for Grave''s disease include radio-iodine ablation, which is the standard treatment in the USA, antithyroid drug therapy, which is popular in Japan, and surgery, which is commonly employed in Europe and India. There are very few reports about the outcome of surgery in Grave''s disease in the Indian setting. Surgery for Grave''s disease is an attractive option in under developed countries to cut short prolonged drug treatment, costly follow up and avoid the need for radio-isotope facilities for 1311 ablation. Aim of the present study was to assess the result of subtotal thyroidectomy in 32 cases of Grave''s Disease referred for surgery by the endocrinologist in a teaching hospital. Patients were prepared for surgery with Lugol''s iodine and propranalol. Subtotal thyroidectomy was performed by a standard technique, which included dissection and exposure of recurrent laryngeal nerves and parathyroid glands. Actual estimation of weight of the remnant gland was not part of the study. Duration of follow up ranged from 6 months to 4 years. 13 of 32 cases were males. Age ranged from 20 to 57 years. There was 1 death in the immediate post-operative period. There were no cases of permanent hypoparathyroidism or recurrent laryngeal nerve palsy. 1 patient developed temporary hypoparathyroidism. 1 patient developed recurrence of hyperthyroidism and 3 cases developed hypothyroidism all within 2 years of surgery. The study has demonstrated the safety and effectiveness of surgery for Grave''s Disease in comparison to the reported high incidence of hypothyroidism following radio-iodine therapy and high recurrence rate after anti thyroid drug therapy.Key Words: Grave''s Disease, Thyroidectomy