Cancer epidemiology in mainland South-East Asia - past, present and future

The countries of mainland South-East Asia, Myanmar, Thailand, Laos, Cambodia and Viet Nam, share a long history of interactions and many cultural similarities, as well as geographical contiguity. They therefore can be usefully examined as a group when considering measures for control of cancer and other non-communicable diseases. Liver cancer is consistently found at higher incidence than most other parts of Asia, with lung cancer as the other most important neoplasm in males. In females cervical and breast cancer about equally predominate, throughout. However, there are also major differences, particularly with regard to stomach and nasopharyngeal cancer, only found at relatively high incidence in Viet Nam. The present review was conducted to gather together registry data on cancer prevalence and epidemiological findings cited in PubMed in order to obtain as comprehensive picture as possible of the present status. It is hoped that future cooperation across the region will facilitate development of coordinated cancer control programs to reduce the burden.

Closely related HIV-1 CRF01_AE variant among injecting drug users in northern Vietnam: evidence of HIV spread across the Vietnam-China border

To investigate the nature of recent HIV outbreaks among injecting drug users (IDUs) near the Vietnam-China border, we genetically analyzed 24 HIV-positive blood specimens from 2 northern provinces of Vietnam (Lang Son and quang Ninh) adjacent to the China border, where HIV outbreaks among IDUs were first detected in late 1996. Genetic subtyping based on gag (p17) and env (C2/V3) sequences revealed that CRF01_AE is a principal strain circulating throughout Vietnam, including the provinces near the China border. The majority of CRF01_AE sequences among IDUs in Quang Ninh and Lang Son showed significant clustering with those found in nearby Pingxiang City of China's Guangxi Province, sharing a unique valine substitution 12 amino acids downstream of the V3 loop. This particular subtype E variant, uniquely found among IDUs in northern Vietnam and southeastern China, is designated E(v). The genetic diversity of CRF01_AE distributed in Quang Ninh (1.5 +/- 0.6%) and Pingxiang City (1.9 +/- 1.2%) was remarkably low, indicating the emerging nature of HIV spread in these areas. It is also noted that the genetic diversity of CRF01_AE among IDUs was consistently lower than that in persons infected sexually, suggesting that fewer closely related CRF01_AE variants were introduced into IDUs and, conversely, that multiple strains of CRF01_AE had been introduced via the sexual route. The data in the present study provide additional evidence that HIV outbreaks among IDUs in northern Vietnam were caused by the recent introduction of a highly homogeneous CRF01_AE variant (E(v)) closely related to that prevailing in nearby southern China.

The potency (ED50) and cardiovascular effects of rapacuronium (Org 9487) during narcotic-nitrous oxide-propofol anesthesia in neonates, infants, and children

We studied the neuromuscular blocking effects of rapacuronium (Org 9487) (dose-response curve, onset, and 50% effective dose [ED50] value), and changes in heart rate and blood pressure, as well as evidence of histamine release in neonates, infants, and children in an open-label, randomized, two-center study. Fifteen neonates, 30 infants, and 30 children were studied. Anesthesia was induced and maintained with propofol, nitrous oxide:oxygen (60:40), and fentanyl. Mechanomyographic monitoring of neuromuscular function was performed at the thumb. The potency (ED50) for neonates, infants, and children were 0.32 (95% confidence interval [CI] 0.15-0.61), 0.28 (95% CI 0.11-0.61), and 0.39 (95% CI 0.17-0.85) mg/kg, respectively. Neonates who received 0.3, 0.6, or 0.9 mg/kg Org 9487 developed a maximum T1 twitch depression of 34 +/-28%, 98 +/- 3%, and 99 +/- 2%, respectively. Time-to-peak effect (onset time) for 0.9 mg/kg Org 9487 was 57 +/- 20 s. Maximum percent T1 twitch depression (+/-SD) in infants who received 0.3, 0.6, or 0.9 mg/kg rapacuronium was 41 +/- 34%, 96 +/- 7%, and 100 +/- 1%, respectively. Time-to-peak effect for 0.9 mg/kg Org 9487 was 62 +/- 29 s. In children 0.3, 0.6, and 0.9 mg/kg rapacuronium resulted in an average percent T1 twitch suppression of 29 +/- 23, 83 +/- 11, and 90 +/- 16, respectively. Time-to-peak effect of 0.9 mg/kg Org 9487 was 96 +/- 33 s, respectively. There was no evidence of histamine release or significant changes in heart rate or blood pressure in either group at any dose. Rapacuronium is a low-potency nondepolarizing muscle relaxant with a fast onset of relaxation and minimal cardiovascular effects. Its potency (ED50) is similar in neonates (0.32 mg/kg), infants (0.28 mg/kg), and children (0.39 mg/kg). T1 suppression (90% +/- 16) is less and time to peak effect (96 +/- 33 s) is greater (0.9 mg/kg rapacuronium) in children, compared with the combined group of infants and neonates.

IMPLICATIONS

This study assesses the potency of rapacuronium (Org 9487) in pediatric patients. The potency of rapacuronium is similar in neonates (0.32 mg/kg), infants (0.28 mg/kg), and children (0.39 mg/kg).

Long-term nitric oxide blockade in the pregnant rat: effects on blood pressure and plasma levels of endothelin-1

OBJECTIVE

Abnormalities in the production of nitric oxide and endothelin-1 have been implicated in the development of preeclampsia. We postulated that long-term nitric oxide synthase inhibition with L-nitro-arginine methyl ester would induce sustained hypertension, a rise in plasma levels of endothelin-1, and fetal growth restriction.

STUDY DESIGN

Conscious virgin and pregnant Sprague-Dawley rats received infusions of vehicle or L-nitro-arginine methyl ester (2.5 mg/kg/hr) for 11 days. Mean arterial pressure was assessed serially. On day 21 of gestation (or equivalent in virgin rats) plasma was collected for endothelin-1 levels; pup weight and litter size were determined. Data were analyzed with analysis of variance and regression techniques.

RESULTS

Mean arterial pressure was constant in virgin control rats (n = 7) but declined in pregnant control rats (n = 11) as gestation advanced. Nitric oxide synthase inhibition in virgin (n = 10) and pregnant (n = 11) rats caused sustained elevations in mean arterial pressure (165 +/- 7 vs 100 +/- 3 mm Hg, L-nitro-arginine methyl ester vs control virgin rats, p < 0.0001; 149 +/- 5 vs 91 +/- 2 mm Hg, L-nitro-arginine methyl ester vs control pregnant rats, p < 0.0001). L-nitro-arginine methyl ester induced a rise in plasma endothelin-1 levels in virgin (4.4 +/- 0.1 vs 3.5 +/- 0.1 pg/ml, L-nitro-arginine methyl ester vs control, p < 0.0001) and pregnant rats (3.0 +/- 0.1 vs 2.6 +/- 0.1 pg/ml, L-nitro-arginine methyl ester vs control, p < 0.0001). Pregnant rats had lower endothelin-1 levels than did virgin rats (p < 0.0001). Mean arterial pressure and endothelin-1 were significantly correlated in pregnant rats. L-nitro-arginine methyl ester decreased pup weight (2.4 +/- 0.4 vs 3.7 +/- 0.2 gm/pup/litter, L-nitro-arginine methyl ester vs control, p < 0.01) and litter size (6.6 +/- 1.3 vs 10.2 +/- 0.9 pups/litter, L-nitro-arginine methyl ester vs control, p < 0.05).

CONCLUSIONS

Long-term nitric oxide synthase blockade causes sustained hypertension, elevated levels of endothelin-1, and fetal growth restriction. Although the endocrine and pressor effects are not unique to pregnancy, this model clearly induces some of the changes seen in preeclampsia and may be useful for studying specific interventions.

Uremic serum subfraction inhibits apolipoprotein A-I production by a human hepatoma cell line

Abnormalities in lipoprotein metabolism are common in uremic patients and may represent an additional risk factor for the development of atherosclerosis. Despite the frequent occurrence of lipoprotein abnormalities, the role of various serum toxins and subfractions that accumulate in uremic patients on lipoprotein metabolism is not clearly understood. This study addressed the role of uremic toxins on lipoprotein metabolism by examining the effect of a 500 to 2,000-d subfraction obtained from the serum of uremic and control subjects on the synthesis of apolipoprotein (apo) A-I in a human hepatoma cell line (Hep-G2). Serum subfractions obtained from uremic patients inhibited apo A-I synthesis and secretion by Hep-G2 cells in a dose-dependent manner as measured by (3H)leucine incorporation into apo A-I, immunoprecipitation, and ELISA. The uremic serum subfraction decreased the mRNA expression for apo A-I in Hep-G2 cells when compared with controls. These observations suggest that a component of uremic serum can have the potential to inhibit hepatic apo A-I synthesis and may adversely influence high-density lipoprotein metabolism, thus increasing the risk for the development of atherosclerotic vascular complications in uremic patients.