[Natural forming causes of China population distribution].

The diverse natural environment in China causes the spatial heterogeneity of China population distribution. It is essential to understand the interrelations between the population distribution pattern and natural environment to enhance the understanding of the man-land relationship and the realization of the sustainable management for the population, resources, and environment. This paper analyzed the China population distribution by adopting the index of population density (PD) in combining with spatial statistic method and Lorenz curve, and discussed the effects of the natural factors on the population distribution and the interrelations between the population distribution and 16 indices including average annual precipitation (AAP), average annual temperature (AAT), average annual sunshine duration (AASD), precipitation variation (PV), temperature variation (TV), sunshine duration variation (SDV), relative humidity (RH), aridity index (AI), warmth index ( WI), > or = 5 degrees C annual accumulated temperature (AACT), average elevation (AE), relative height difference (RHD), surface roughness (SR), water system density (WSD), net primary productivity (NPP), and shortest distance to seashore (SDTS). There existed an obvious aggregation phenomenon in the population distribution in China. The PD was high in east China, medium in central China, and low in west China, presenting an obvious positive spatial association. The PD was significantly positively correlated with WSD, AAT, AAP, NPP, AACT, PV, RH, and WI, and significantly negatively correlated with RHD, AE, SDV, SR, and SDTS. The climate factors (AAT, WI, PV, and NPP), topography factors (SR and RHD), and water system factor (WSD) together determined the basic pattern of the population distribution in China. It was suggested that the monitoring of the eco-environment in the east China of high population density should be strengthened to avoid the eco-environmental degradation due to the expanding population, and the conservation of the eco-environment in the central and west China with vulnerable eco-environment should also be strengthened to enhance the population carrying ability of these regions and to mitigate the eco-environmental pressure in the east China of high population density.

Clinical predictors of obstructive sleep apnea in Asian bariatric patients.

BACKGROUND: Obstructive sleep apnea (OSA) is a common disorder in modern society and closely associated with obesity. Because OSA increases the likelihood of complications in the perioperative period, preoperative recognition is very important for bariatric patients. Polysomnography (PSG) remains the gold standard for diagnosis, but it is a time-consuming and expensive examination. Our study is aimed at identifying practical clinical predictors of OSA for bariatric patients. METHODS: From April 2006 to December 2007, 101 morbid obese patients [41 men and 60 women, mean age 30.3 +/- 8.5, mean body mass index (BMI) 43.3 +/- 6.9] who underwent PSG before bariatric surgery were retrospectively studied. The severity of OSA was categorized by the apnea-hypopnea index (AHI) as follows: normal, 0 to 4.9; mild, 5 to 14.9; moderate, 15 to 29.9; and severe, >/=30. Chi-squared tests and linear regression models were used to assess associations between clinical parameters and AHI; P < 0.05 was considered statistically significant. RESULTS: The mean Epworth sleepiness scale (ESS) score was 8.2 +/- 4.7, and the mean AHI was 28.9 +/- 33.8 per hour. Of 101 patients, 83 patients had OSA; including severe (32.7%), moderate (17.8%), and mild (31.7%) OSA; 18.5% had no OSA. Patients with severe OSA are significantly male predominant and had higher BMI, systolic blood pressure, hemoglobin, neck and waist circumference, and ESS scores. In linear regression model analysis, the parameters which positively correlated with AHI were body weight, BMI, systolic blood pressure, diastolic blood pressure, hemoglobin, waist and neck circumferences, and the scores of ESS. Multivariate analysis confirmed that BMI, neck circumference, and scores of ESS are independent predictors of the increasing of AHI. CONCLUSIONS: OSA is highly prevalent (82.2%) in Asian bariatric patients. BMI, neck circumference, and scores of ESS are independent predictors of OSA in these patients.

Serum C-reactive protein and white blood cell count in morbidly obese surgical patients.

BACKGROUND: Obesity has been widely recognized as a chronic inflammatory condition and associated with elevated inflammatory indicators including C-reactive protein (CRP) and white blood cell count (WBC). Recent studies have shown elevated CRP or WBC is a significant risk factor for cardiac events and stroke but the clinical significance of CRP and WBC has not been clearly studied in morbidly obese patients. This study is aimed at the clinical significance of WBC and CRP in morbidly obese patients and the change after bariatric surgery. METHODS: The study was a prospectively controlled clinical study. From December 1, 2001 to January 31, 2006, of 640 (442 females and 198 males) consecutive morbid obese patients enrolled in a surgically supervised weight loss program with at least 1 year's follow-up were examined. RESULTS: Of the patients, 476 (74.4%) had elevated CRP and 100 (15.6%) had elevated WBC at preoperative study. CRP and WBC were significantly related and both increased with increasing body mass index (BMI). CRP is also increased with increasing waist, glucose level, hemoglobin, albumin, Ca, insulin, C-peptide, and metabolic syndrome while WBC is increased with metabolic syndrome but decreased with increasing age. Multivariate analysis confirmed fasting glucose level and hemoglobin are independent predictors of the elevation of CRP while age is the only independent predictor for elevated WBC. Both WBC and CRP levels decreased rapidly after obesity surgery. These improvements resulted in a 69.8% reduction of CRP and 26.4% reduction of WBC 1 year after surgery. Although individuals who underwent laparoscopic gastric bypass lost significantly more weight (36.8 +/- 11.7 kg vs. 17.3 +/- 10.8 kg; p = 0.000) and achieved a lower BMI (27.8 +/- 4.6 vs. 35.0 +/- 5.5; p = 0.000) than individuals who underwent laparoscopic gastric banding, there was no difference in the resolution of elevated CRP 1 year after surgery (95.9% vs. 84.5%; p = 0.169) and WBC (99.4% vs. 98.3%; p = 0.323). CONCLUSIONS: Both baseline WBC and CRP are elevated in morbid obese patients but CRP has a better clinical significance. Significant weight reduction 1 year after surgery markedly reduced CRP and WBC with a resolution rate of 93.9% and 98.2% separately. Obesity surgery performed by laparoscopic surgery is recommended for obese patients with elevated CRP or WBC.