维持性血液透析患者血浆同型半胱氨酸与骨密度的相关性研究

目的 探讨维持性血液透析（MHD）患者血浆同型半胱氨酸（Hcy）与指骨骨密度（BMD）的关系.方法 选择2006年2月至2010年2月在我院住院的MHD患者94例,分别将男性和女性患者分为3组,骨质疏松组：T值＜-2;骨量减少组：T值-2～-1;正常骨量组：T值＞-1.分别比较3组男性和3组女性患者年龄、血钙、血磷、碱性磷酸酶（ALP）、血浆Hcy.对血浆Hcy水平与指骨BMD进行相关性分析,用逐步回归法以指骨BMD为自变量建立多元线性回归方程以分析指骨BMD的影响因素.结果 骨质疏松组年龄均大于骨量减少组和正常骨量组（P＜0.05）,骨量减少组年龄大于正常骨量组（P＜0.05）.3组血钙、血磷、ALP、Hcy差异无统计学意义（P＞0.05）.男性血浆Hcy水平与指骨BMD无相关性（r=0.267,P＞0.05）.年龄是指骨BMD的影响因素（回归系数b1=-0.002,P=0.022）.骨质疏松组血浆Hcy水平均高于骨量减少组和正常骨量组（P＜0.05）,而骨量减少组和正常骨量组Hcy差异无统计学意义（P＞0.05）.3组血钙、血磷、ALP差异无统计学意义（P＞0.05）.女性血浆Hcy水平与指骨BMD呈负相关（r=-0.527,P＜0.05）.年龄和Hcy是指骨BMD的影响因素（回归系数b1=-0.002,P=0.011;回归系数b4=-0.003,P=0.048）.结论 女性MHD患者高血浆Hcy水平可能与指骨BMD降低有关,男性MHD患者血浆Hcy水平与指骨BMD无相关性.血浆Hcy升高可能是女性MHD患者骨质疏松潜在的危险因素.     

大庆地区1096例汉族人群骨密度调查及骨质疏松发生率分析

目的 调查大庆市1096例健康汉族人群骨密度,了解该地区健康人群骨量峰值、骨密度变化的规律及骨质疏松发生率。方法 采用美国GE公司生产的Luner Prodigy Advance型骨密度仪,检测受试者腰椎和股骨颈骨密度（BMD）。将1096例检测结果按不同性别每5岁为1年龄组,应用SPSS19.0软件统计分析骨密度测量指标及骨质疏松（OP）发生率。结果 大庆市汉族男、女性人群腰椎骨密度峰值分别为1.197±0.203、1.192±0.145,股骨颈骨密度峰值分别为0.977±0.157、0.918±0.128。其峰值骨量年龄男性为45～49岁,50岁以后开始缓慢下降。其峰值骨量年龄女性为40～49岁,50岁以后开始缓慢下降。50～54岁年龄段男性骨质疏松症发生率为5.56%,女性为5.67%;55～59岁年龄段男性骨质疏松症发生率为7.32%,女性为11.51%;60～64岁年龄段男性骨质疏松症发生率为15.15%,女性为28.28%;65～69岁年龄段男性骨质疏松发生率为26.67%,女性为29.41%;70～74岁年龄段男性骨质疏松发生率为25.00%,女性为44.44%;75～79岁年龄段男性骨质疏松发生率为36.36%,女性为77.78%;80岁以上男性骨质疏松发生率为66.67%,女性为83.33%。结论 大庆市汉族人群不同年龄及同年龄组两性之间比较骨密度测定值差异显著（P<0.01）。55岁以后各年龄段女性骨质疏松发生率明显高于男性（P<0.01）。本研究报告的骨密度峰值大于沈阳地区,与合肥地区相近,略低于贵阳地区。OP发生率与合肥地区比较相近,略低于沈阳地区。     

血清铁蛋白水平与骨密度的相关性研究

目的分析绝经后女性及50岁以上男性不同骨量人群血清铁蛋白的差异,探讨血清铁蛋白水平与骨密度的相关性。 方法选择2018年9月至2019年2月期间于河北医科大学第三医院就诊,接受双能X线骨密度测量仪（DEXA）检测骨密度（BMD）的绝经后女性（131例）及50岁以上男性（65例）患者（共196例）,根据BMD分为骨量正常组（46例）、骨量减少组（68例）和骨质疏松组（82例）。收集上述患者的临床资料,检测相关生化指标,并测定血清铁蛋白水平,评估血清铁蛋白与骨密度的相关性。 结果（1）与骨量正常组[99.50（91.55,128.51）ng/ml]和骨量减少组[103.36（93.26,113.46）ng/ml]相比,骨质疏松组血清铁蛋白水平明显增高[（174.25（160.85,210.42）ng/ml）（χ²=100.573,P=0.000）。（2）血清铁蛋白水平与髋部、腰椎骨密度均呈负相关,（髋部r=-0.487,P<0.05;腰椎r=-0.531,P<0.05）。（3）体重为骨质疏松症的保护因素（r=0.049,P<0.05）,血清铁蛋白为骨质疏松症的危险因素（r=-0.018,P<0.05）。 结论血清铁蛋白水平增高是骨质疏松症的危险因素,在骨质疏松症的发生中可能起重要作用。     

重庆市1424例健康体检者超声桡骨骨密度检测结果分析

目的 了解位于西南地区的重庆市健康成年男性、女性的骨密度现状,为骨质疏松症的筛查、预防提供科学依据。方法 采用Sunlight OmnissenseTM 7000超声骨密度仪,调查测量了自2012年9月~2013年1月期间在西南大学体检中心参加健康体检的1424(女性643,男性781)名汉族成年人桡骨远端骨密度,根据T值判定骨量减少和骨质疏松,并计算其检出率。结果 女性骨量减少248例,检出率为38. 57%,骨质疏松187例,检出率为29. 08% ;男性骨量减少339例,检出率为43. 41%,骨质疏松96例,检出率为12. 29%。重庆地区骨量减少和骨质疏松的检出率与贵阳、广州、北京地区比较男性在20岁段~40岁段均有显著差异(P <0. 001),与杭州地区相比男性在20岁段、30岁段、60岁段、70岁段有显著差异（P <0.001）,与沈阳地区相 比男性在20岁段、50岁段、60岁段均有差异(P <0. 05);与贵阳地区比较女性在50岁段和70岁段有显著差异（P <0. 001), 与广州地区相比女性在20岁段、40岁段、60岁段、70岁段均有显著差异(P < 0. 001),与杭州、沈阳地区相比女性在50岁段和 60岁段有显著差异(P <0. 001),与北京地区相比女性在20岁段~50岁段有显著差异（P <0. 001)。结论 重庆地区男女性 在50岁以前T值水平相当并保持相对稳定,50岁以后女性T值明显低于男性;随年龄增加男女性T值均逐渐下降,女性在围绝经期下降迅速。重庆地区在骨量减少及骨质疏松的检出率上较我国其他地区处于中等水平。     

2510名浙江居民指骨骨密度检测结果分析

目的 了解受检人群的指骨骨密度(BMD)情况,为骨质疏松的防治计划奠定基础.方法 通过健康快车活动在2011年6月至2011年7月在浙江省对2510名志愿者(男性734人,女性1776人,年龄范围20～85岁,平均为55.62±14.13岁)的指骨骨密度数据进行分析.结果 受检人群骨量峰值出现在35～40年龄组,男性＞65岁和女性＞50岁BMD低于35 ～ 40年龄组(P＜0.05);三指骨骨密度有差别,MP3＞ MP2＞ MP4(F =493.647,P=0.000);男性BMD高于女性(F=788.027,P=0.000).男性20～40年龄组骨质正常占86.32％,50～60年龄组骨质正常为80.86％,而到70～85年龄组骨质正常只有56.02％;女性20～40年龄组骨质正常占88.51％,50～60年龄组骨质正常为52.29％,而到70 ～ 85年龄组骨质正常只有13.27％.结论 浙江省受检人群的指骨BMD有明显的性别和年龄差异,其中女性＞50岁指骨BMD呈直线下降趋势,应加强对这一人群骨质疏松的预防和治疗;指骨骨密度仪简易、快速、便携、有效,作为普查工具具有一定的可行性.     

双能X线吸收法腰椎侧位骨密度测定的临床研究

目的评价双能X线吸收法测定腰椎骨密度时侧位的临床价值。方法178例女性患者(按年龄分组)接受腰椎后前位和侧位骨密度测定,以BMD表示骨密度值,以T值为标准判断骨量正常、骨量减少和骨质疏松,评价腰椎后前位与侧位T值对骨量减少程度的判断和骨质疏松诊断的差别。结果①各年龄组患者腰椎后前位BMD值均高于侧位值;②各年龄组患者腰椎后前位及侧位T值对骨量减少程度的判断有显著性差别;③当大于50岁时,腰椎后前位及侧位T值对骨质疏松诊断有显著性差别。结论腰椎侧位对女性患者骨量减少程度的判断和骨质疏松的诊断(>50岁)都有一定临床价值。     

氧化应激和骨代谢水平与老年原发性骨质疏松症间的相互关系

目的 探讨氧化应激、骨代谢水平与老年原发性骨质疏松症间的相互关系。方法 回顾性分析2012年5月至2013年12月间,我院体检的老年患者共62例,平均年龄为72.39岁（62~92岁）,其中男性30例,女性32例,根据BMD结果分为骨量正常组14例,骨量减少组19例,骨质疏松组29例。所有患者均抽取外周血,检测AOPP、SOD、β-CTX和tPINP水平。应用SPSS10.0对3组的数据进行比较分析。 结果 骨质疏松组中血清AOPP高于骨量减少组和骨量正常组,SOD水平则在骨质疏松组中最低（P<0.05）。各组间β-CTX和tPINP水平无统计学差异。相关性检测提示AOPP与BMD（r=-0.59,P<0.00）、SOD(r=-0.58,P<0.00)呈负相关,与β-CTX(r=-0.31,P<0.02)、年龄(r=0.53,P<0.00)呈正相关。同时,为明确各指标对BMD的影响,采用线性回归方程分析后发现,血清AOPP和SOD水平对BMD影响较大。结论 氧化应激可引起骨代谢紊乱,主要表现为骨破坏增加,可影响老年患者BMD,对老年原发性骨质疏松症的发生和发展有重要影响,抗氧化治疗可能对该病有一定的疗效。     

武汉地区1359例骨密度测定及骨质疏松患病率分析

目的 分析武汉地区人群骨密度（BMD）变化规律及骨质疏松（OP）患病率。方法 使用美国Hologic公司双能X线骨密度仪对武汉地区2－91岁的居民1359人进行L1－4和髋部BMD测定,然后进行比较和统计分析。结果 男性腰椎骨峰值在30－34岁年龄段,女性在35－39岁;男、女性髋部骨峰值均在30－34岁。峰值后随年龄增长BMD逐渐下降,女性在50岁后可见明显的骨质丢失加速,而男性丢失是逐渐和缓慢的。武汉地区50－79岁人群骨质疏松症发病率男性为37．8％,女性为67．3％。结论 骨质疏松研究的重点在中老年妇女,但对于男性也不可忽视;骨质疏松的预防应从青少年开始。     

晋城地区健康人群前臂骨峰值骨量的建立

目的：建立晋城地区健康人群前臂骨密度（ BMD）的峰值骨量和标准差值,为开展周围型双能X线骨密度仪测定及骨质疏松症研究提供基础数据。方法采用韩国产双能X线骨矿测量仪（ EXA－3000）对晋城地区1400例21～55岁的健康体检人群进行左侧前臂骨密度测定,进行非优势侧（左侧）前臂远端尺桡骨的BMD值测定,并分析其年龄分布,建立晋城地区健康人群前臂远端骨密度的峰值骨量和标准差值。骨质疏松的骨量诊断以骨量峰值的均数±标准差的形式建立,均数的计算采用三次方回归方程模型进行拟合。结果男、女性前臂骨的BMD值均符合正态分布,可采用均数±标准差（ xˉ±s）的形式表示。40岁以前男、女性前臂骨的BMD值均随年龄增加而逐步上升,且各年龄段BMD值的差异有统计学意义（P＜0．05）。45岁以后男、女性前臂骨的BMD值开始下降,且50岁以后下降明显（ P＜0．05）。男、女性前臂骨的骨量峰值均出现在41～45岁年龄段。男、女性前臂远端尺桡骨的骨量峰值及标准差分别为（0．5682±0．0647）g／cm2、（0．4209±0．0689）g／cm2。结论建立了晋城地区健康人群男、女性前臂骨的骨量峰值和标准差,为周围型双能X线骨密度仪测定并开展骨质疏松症的研究提供基础数据,尤其是用于高危人群筛查,以便确定是否需要进一步开展中轴骨测量或进行药物治疗。     

广州地区中老年人群骨量减少及骨质疏松患病率的调查

目的：了解广州地区中老年人骨量减少（Osteopenia）及骨质疏松（Osteoporosis,OP），患病率的变化规律，为防治OP提供科学依据。方法：居住广州市内及郊区农村20年以上的40岁以上人群进行整群随机抽样，样本共1160人，准确记录其性别和年龄后，用美国Lunar公司的DEXA测试受试者L2－4和髋部的骨密度（BMD），然后进行统计、比较与分析。结果：40岁组女性L2－4及Ward‘s区BMD高于男性，该组骨量减少患病率男女性都超过样本数的1／3，50岁以男性高于女性，男性70岁组L2－4下降才明显，女性L2－4及髋部BMD从50岁起加速下降，L2－4BMD70岁以后减慢，男性60岁以后髋部BMD下降明显，不论男、女性髋部BMD下降直到80岁以上都较显著，骨质疏松患病率随年龄的增长而增加，女性50岁组起变化开始明显，60岁组OP患病率85％，并一起以重度OP占多数，农村患病率高于城市，男性在70岁组起OP患病率显著上升，结论：广州地区中老年人骨量减少及OP患病率与北京、上海、成都等地区近似，老年女性以重度OP占多数，50岁以上男性OP患病率达到30％，应得到足够的重视。     

Bone mineral density in elderly men and women: results from the Framingham osteoporosis study.

Our study investigated bone mineral density of the proximal femur and ultradistal and proximal radius in a population of elderly men and women. The Framingham study started in 1948, following a population-based sample for evaluation of cardiovascular risk factors and events. During the 20th biennial Framingham examination (1988-89) we conducted the Framingham osteoporosis study, measuring bone mineral density in the proximal femur and distal and proximal radius for 1154 study participants. Ages ranged from 68 to 98 years, with a mean age of 76 years. Bone mineral density was measured using Lunar SP2 and DP3 densitometers. This cross-sectional study evaluates mean bone mineral density measurements at each site by 5 year age intervals for men and women, testing for trends in bone density with age. Analyses were repeated adjusting for weight and height. Among the 446 and 708 women, bone mineral density of the femur and bone mineral content of the proximal radius were inversely and significantly related to age in both sexes and were considerably higher in men than women at all sites. The linear decline with age group in our cross-sectional study remained after multivariate adjustment for height and weight. The ultradistal radius showed no significant correlation with age for either sex. There were significant correlations between the bone measurements made at different sites for both men and women (range in r = 0.27-0.89). Cross-sectional curves of bone mineral density with age showed no significant differences in slope between males and females.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prämature Atherosklerose

Coronary heart disease (CAD) is the leading cause of death in men and women. However, men develop heart disease about 10 years earlier, which reduces their average life expectancy by about 6 years. The cause is the high incidence of premature atherosclerosis in men. In fairly young and middle-aged men with the same blood pressure or cholesterol levels as women cardiovascular risk is double that in women the same age, or the same as in women 10 years older but with the same risk factor profile otherwise. This means that like age, male sex is a cardiovascular risk factor that noone can do anything about. The sex difference does not even out until after the age of 75 years and cannot be explained on the basis of the different sex hormones. The data currently available do not allow any definitive explanation for the premature atherosclerosis seen in men. In parallel with CAD, men also suffer more frequently and earlier in life than women from peripheral arterial disease and aortic aneurysms.     

Characteristics of age-related changes in bone compared between male and female reference Chinese populations in Hong Kong: a pQCT study

There have been few comprehensive studies on the age-related changes in bone mineral density (BMD) and bone structure in Chinese people. Using peripheral quantitative computed tomography (pQCT), we assessed volumetric BMD of both trabecular and cortical bone and their geometry at both radius and tibia in 620 Chinese men and 638 women, aged 20–98 years, in Hong Kong. Cortical BMD did not start declining until after the age of 50 years in women and the age of 60 years in men. In contrast, trabecular BMD declined with age starting from adulthood in both sexes, and the rates of decline accelerated after the age of 50 years only in women. The integral and trabecular bone area expanded with age in older men and women, primarily at the tibia. Cortical bone area decreased significantly in older women, particularly at the tibia, while it decreased only slightly with aging in men. The moment of inertia decreased with age at the radius in older men and women. At the tibia, age-related decline accelerated in older women, but not in older men. It was concluded that trabecularization of bone in response to declining BMD and mechanical loading may be maladaptive by reducing cortical bone area, if periosteal apposition cannot keep pace with it.     

Chronic pain syndromes in orthopedics--typical sites, follow-up and patient characteristics

This epidemiological questionnaire--study about 362 patients suffering from chronic pain related to muscle skeletal disorders shows the following results: most muscle skeletal pain syndromes are located in the area of the head and back (57.5%), patients who want to be treated in an orthopedic pain ambulance, suffer from at least "moderate" pain according to the verbal rating scale and at least from pain equal or more than 50 according to the numeric rating scale, for most patients (51.9%) the duration of the pain has been between 1 and 10 years, about twice as many women (60.5%) than men (39.5%) suffer from chronic muscle skeletal pain, pain syndromes seem to be of more chronic duration in women than in men, and women tend to take pain killers more frequently than men, most patients with chronic pain consult 2 to 6 doctors, for typical orthopedic pain syndromes most patients consult an orthopedic doctor, patients suffering from chronic headache consult an orthopedic specialist about as frequently as an neurologist or internal specialist.     

Epidemiology and pathophysiology of osteoporosis in men

Osteoporosis in men is an unrecognized but growing problem as the number of men who live to old age increases. The 10-year fracture risk at age 50 quadruples by age 80, and in general the incidence rate of osteoporotic fracture in men is about half that of women. Of note, the mortality and morbidity after hip fracture are much greater in men. There are many men whose osteoporosis is the result of specific causes such as oral glucocorticoid therapy, hypogonadism, or androgen withdrawal therapy for prostate cancer. In addition there are several interesting syndromes of osteoporosis in middle-aged men; these men usually present with vertebral fractures. As knowledge about the prevalence and etiology of osteoporosis in men increases, it will be recognized and treated in more men, in hopes of preventing fracture.     

The saddle lift for tight thighs

Efforts to tighten the lateral thigh skin and subcutaneous tissue after liposuction may result in conspicuous scars on the hips, groin crease, or medial thighs. We have developed a technique that enables the excision of skin and subcutaneous tissue, measuring about 20 × 10 cm², from the inner thigh and central buttocks crease where the scar can be completely hidden. We present a patient who, after appropriate liposuction, had a nearly perfect silhouette but who continually complained about the looseness of the skin on her lateral and posterior hips. The patient suggested that we remove the skin and subcutaneous tissue from the middle portion. We did so and the results were surprisingly good. We recommend this procedure for those patients in whom no external scar is acceptable and who require tightening of the skin of the upper thighs and buttocks.     

Role of calcium and vitamin D in the prevention (and treatment) of osteoporotic fracture

The skeleton requires optimum development and maintenance of its integrity to prevent fracture throughout the life cycle. It is now generally accepted that bones break because the loads placed on them exceed their ability to absorb the energy involved. Current figures for the UK suggest that 1 in 3 women and 1 in 12 men over the age of 55 years will suffer from osteoporosis in their lifetime, at a cost of £1.7 billion per annum to the NHS. The pathogenesis of osteoporosis is multifactorial. Both the development of peak bone mass and the rate of bone loss are determined by key endogenous and exogenous factors. Re-defining vitamin D requirements in the UK is urgently needed because there is evidence of extensive hypovitaminosis D in men and women, which is especially prevalent in Asian population groups. Low vitamin D status is associated with an increased risk of falling and a variety of other health outcomes, and is an area that requires urgent attention. Calcium supplementation seems to have little effect on bone mineral density in younger post-menopausal women (< 5 years past the menopause) who are not vitamin D deficient, but calcium supplements may be effective in reducing bone loss in late menopausal women (> 5 years post-menopause), particularly in those with low habitual calcium intake (< 400 mg/day). Vitamin D and calcium supplementation have been shown to reduce fracture rates in the institutionalized elderly, but controversy remains about whether supplementation is effective in reducing fracture in free-living populations.     

双能X线骨密度仪测定成都市城区771例健康人骨密度结果分析

目的观察成都市城区健康人群骨密度变化规律,建立该型骨密度仪成都地区骨密度正常值,为骨质疏松诊断、防治提供参考依据。方法①采用EXPERT-XL双能X线骨密度仪(美国 LUNAR公司生产)测定成都市城区健康体检者771例,其中男性300例,女性471例,测量部位包括腰椎1～4和髋部;②按年龄、性别分别输入数据,以10岁为一年龄组,分别计算各组骨密度值,结果以x-±s表示。结果男性腰椎及股骨近端骨密度峰值出现在30～39岁,女性腰椎及股骨近端骨密度峰值出现在20～29岁,随着年龄增加,骨密度逐渐降低,男性在70岁后腰椎骨密度有反弹,而女性在50～59岁间骨密度下降迅速。结论本组健康人群骨密度数据将为成都地区骨质疏松诊断、防治提供参考依据;分析男性腰椎骨密度时应结合股骨近端骨密度;女性50岁后应注意预防、治疗骨质疏松,男性骨质疏松不容忽视。     

Fracture prediction from bone mineral density in Japanese men and women.

In a cohort of 2356 Japanese elderly, after adjusting for age and prevalent vertebral fracture, baseline BMD predicted the risk of spine and hip fracture with similar RR to that obtained from previous reports in whites. The RR per SD decrease in BMD for fracture declined with age. INTRODUCTION: Low bone mineral density (BMD) is one of the most important predictors of a future fracture. However, we are not aware of any reports among Japanese in Japan. MATERIALS AND METHODS: We examined the association of BMD with risk of fracture of the spine or hip among a cohort of 2356 men and women aged 47-95 years, who were followed up by biennial health examinations. Follow-up averaged 4 years after baseline measurements of BMD that were taken with the use of DXA. Vertebral fracture was assessed using semiquantitative methods, and the diagnosis of hip fracture was based on medical records. Poisson and Cox regression analysis were used. RESULTS: The incidence was twice as high in women as in men, after adjusting for age. After adjusting for baseline BMD and prevalent vertebral fracture, however, the gender difference was no longer significant. Age, baseline BMD of spine and femoral neck, and prior vertebral fracture predicted vertebral fracture and hip fracture. Loss of absolute BMD of the femoral neck predicted spine fracture, after adjusting for baseline BMD; rates of change in percent BMD, weight, height, body mass index, and age at menopause did not. The predictive value of baseline BMD for vertebral fracture risk was similar in men and women. The relative risk (RR) for vertebral fracture and hip fracture per SD decrease in BMD declined with age, after adjustment for prevalent vertebral fractures. CONCLUSIONS: Baseline BMD, loss of femoral neck BMD, and prior vertebral fracture predict the risk of spine and hip fracture in Japanese with similar RR to that obtained from previous reports in whites. The RR per SD decrease in BMD for fracture declined with age, suggesting that factors other than BMD might play a greater role in the elderly.     

Factors affecting choice of surgical residency training program

BACKGROUND: A significant problem facing American surgery today is the lack of participation from women and minorities. In 1995 and 1996, 15.1 and 15.8% of United States general surgical residency graduates were women. Of our 71 graduates in the last 12 years, 38% were women. The aim of this study was to identify the factors influencing our residents' choice of training program and the reasons why our program has a high percentage of female graduates. METHODS: Between 1989 and 2000, 27 women and 44 men completed general surgical training at our university and 44/71 (59%) responded to our survey. The age at residency completion was 34 +/- 2.2 years for men and 33.9 +/- 2.8 years for women. Fifty-five percent of men and 30% of women went on to fellowship training; and 36% of men and 20% of women are in academia. RESULTS: Factors influencing our graduates' selection of training program are: Only 23% of men had a female faculty as their mentor, whereas 90% of women had a male faculty as their mentor during training. Only 59% of men but 80% of women (P < 0.05) agreed that female medical students need role models of successful female faculty members. Fifty-five percent of men and 45% of women would encourage a female medical student to choose surgery as a career, but 82% of men and 50% of women would encourage a male medical student to do so. Ninety-one percent of men and 85% of women would choose surgery as a career again. CONCLUSIONS: A surgical residency training program with strong leadership, good clinical experience, and high resident morale will equally attract both genders. Women may pay more attention to the program's gender mix and geographic location.