Strengthening tuberculosis patient referral mechanisms among health facilities in Punjab, Pakistan.

OBJECTIVE: To describe approaches to strengthen existing tuberculosis (TB) patient referral mechanisms in Punjab, Pakistan. METHODS: A descriptive intervention study was conducted through medical chart review. All new smearpositive pulmonary TB patients diagnosed at Gulab Devi Hospital, Lahore, who were referred to any of the primary health care (PHC) units in Punjab Province, were enrolled from January to September 2009. TB coordinators at the referral unit maintained an electronic TB referral/transfer register (e-TRTR) as their key referral monitoring tool. RESULTS: Of 444 new smear-positive pulmonary TB patients enrolled in the study, 181 (41%) confirmed that they had arrived and were registered at the receiving PHC units, and another 17 (4%) had gone to other health facilities. Of the 181 access-confirmed patients at the receiving PHC units, seven were confirmed by postal mail, 49 by district TB coordinators, and the remaining 125 only through direct phone calls made by Provincial TB Programme staff. CONCLUSION: The present study indicates that utilisation of a referral register (e-TRTR), appointment of a responsible person for patient referral at the hospital, close monitoring of the referral by telephone and communication with responsible TB coordinators bring about a considerable improvement in the TB patient referral mechanism.

Effects of estrogen replacement therapy on peripheral vasomotor function in postmenopausal women.

Hormone replacement therapy is associated with a reduction in cardiovascular events in postmenopausal women. We have recently found that acute 17 beta-estradiol administration improves endothelium-dependent vasodilation in both the peripheral and coronary circulations of postmenopausal women. The current study was undertaken in 33 estrogen-deficient postmenopausal women (mean age 59 +/- 7 years) to determine if short-term estrogen replacement therapy also improves endothelium-dependent vasodilation in peripheral circulation. Acute intraarterial infusion of estradiol, which increased forearm venous estradiol levels from 16 +/- 11 to 345 +/- 202 pg/ml, potentiated forearm vasodilation induced by the endothelium-dependent vasodilator acetylcholine by 49 +/- 67% (p < 0.001). Acute estradiol also potentiated vasodilation induced by the endothelium-independent vasodilator nitroprusside by 5 +/- 31% (p = 0.04). However, after 3 weeks of transdermal estradiol administration (0.1 mg/day), which achieved an estradiol level of 120 +/- 57 pg/ml, the vasodilator responses to acetylcholine and to sodium nitroprusside were unchanged from initial measurements obtained before acute administration of estradiol. Repeat intraarterial infusion of estradiol in 8 women, while receiving transdermal estradiol, increased forearm venous estradiol levels to 268 +/- 105 pg/ml and again potentiated the vasodilator response to acetylcholine to a similar degree as that observed in the initial study after acute administration of estradiol. Thus, although acute intraarterial infusion of 17 beta-estradiol potentiates endothelium-dependent vasodilation in the forearms of postmenopausal women, this effect is not maintained with a 3-week cycle of systemic estradiol administration. The different effects of acute and chronic estradiol may be due to the lower plasma levels achieved with chronic estrogen administration.

Acute vascular effects of estrogen in postmenopausal women.

BACKGROUND: Although hormone replacement therapy has been associated with reduction of cardiovascular events in postmenopausal women, the mechanisms that mediate this apparent benefit are unclear. Because improvement in vasomotor function may represent one of the beneficial effects of estrogen administration, we investigated the acute effects of physiological levels of estrogen on the vascular responses of estrogen-deficient postmenopausal women. METHODS AND RESULTS: The study included 40 postmenopausal women 60 +/- 8 years old (mean +/- SD), 20 of whom had one or more conditions associated with vascular dysfunction (hypertension, hypercholesterolemia, diabetes, or coronary artery disease). The forearm vascular responses to the endothelium-dependent vasodilator acetylcholine were studied before and during infusion of 17 beta-estradiol into the ipsilateral brachial artery. In 31 subjects, the effect of estradiol on the responses to the endothelium-independent vasodilator sodium nitroprusside was also studied. Women with risk factors for vascular dysfunction had significantly reduced vasodilator responses to acetylcholine (P = .01) and to sodium nitroprusside (P < .001) compared with healthy subjects. Intra-arterial infusion of 17 beta-estradiol increased the forearm venous estradiol concentration from 16 +/- 10 to 318 +/- 188 pg/mL, levels typical of reproductive-age women at midcycle, but caused no vasodilation. However, estradiol potentiated the forearm vasodilation induced by acetylcholine by 18 +/- 30% (P < .001) in women with risk factors for vascular dysfunction and by 14 +/- 23% (P = .03) in healthy women. Estradiol also potentiated the forearm vasodilation induced by sodium nitroprusside in women with risk factors for vascular dysfunction by 14 +/- 21% (P < .001) but not in healthy women. CONCLUSIONS: Physiological levels of 17 beta-estradiol selectively potentiate endothelium-dependent vasodilation in healthy postmenopausal women and potentiate both endothelium-dependent and endothelium-independent vasodilation in post-menopausal women with risk factors for atherosclerosis and evidence of impaired vascular function. These vascular effects may be partly responsible for the long-term benefit of estrogen therapy on cardiovascular events in postmenopausal women.

Effect of increased availability of endothelium-derived nitric oxide precursor on endothelium-dependent vascular relaxation in normal subjects and in patients with essential hypertension.

BACKGROUND: Patients with essential hypertension have a deficit in the endothelium-derived nitric oxide system that results in impaired endothelium-dependent vascular relaxation. The objective of this study was to determine whether this abnormality is caused by a deficiency of substrate for nitric oxide synthesis. METHODS AND RESULTS: The vascular responses to acetylcholine (an endothelium-dependent vasodilator infused at 7.5, 15, and 30 micrograms/min) and sodium nitroprusside (a direct smooth muscle dilator infused at 0.8, 1.6, and 3.2 micrograms/min) were studied during combined administration of dextrose 5% or L-arginine (substrate for nitric oxide synthesis infused at 40 mumol/min) in 12 normal control subjects (seven men and five women; age, 49.3 +/- 7 years) and 14 hypertensive patients (nine men and five women; age, 48.4 +/- 7 years). In addition, the effect of D-arginine (stereoisomer of arginine that is not a precursor of nitric oxide) on the vascular responses to acetylcholine was studied in eight normal control subjects and seven hypertensive patients. Drugs were infused into the brachial artery, and the response of the forearm vasculature was measured by strain gauge plethysmography. The vasodilator response to acetylcholine was significantly blunted in hypertensive patients compared with normal control subjects (maximum flow, 8.9 +/- 5 versus 15.7 +/- 6 mL.min-1.100 mL-1, respectively; p < 0.007); however, no difference was observed in the response to sodium nitroprusside (11.4 +/- 6 and 11.7 +/- mL.min-1.100 mL-1, respectively). L-Arginine did not significantly change basal blood flow or vascular resistance in either group. In normal control subjects, the infusion of L-arginine significantly augmented the vasodilator response to acetylcholine (maximum flow, 15.7 +/- 6 versus 21.4 +/- 8 mL.min-1.100 mL-1 before and after L-arginine, respectively; p < 0.001). In contrast, in hypertensive patients, the infusion of L-arginine did not alter the response to acetylcholine (maximum flow, 8.9 +/- 5 and 8.4 +/- 4 mL.min-1.100 mL-1 before and after L-arginine, respectively). The administration of L-arginine did not modify the response to sodium nitroprusside in either group. Similarly, the infusion of D-arginine did not alter the response to acetylcholine in either group. CONCLUSIONS: In normal humans, availability of substrate for production of nitric oxide is a rate-limiting step for endothelium-dependent vascular relaxation. In contrast, increased availability of nitric oxide precursor does not modify endothelium-mediated vasodilation in hypertensive patients. These findings provide further evidence of a defect in the endothelium-derived nitric oxide system in hypertension and indicate that this abnormality is not related to decreased availability of substrate for nitric oxide production.