Metabolic and cardiovascular risk factors in Klinefelter syndrome

Klinefelter syndrome (KS), which normally presents with a 47,XXY karyotype, is the most common sex chromosome disorder in males. It is also the most common genetic cause of male infertility. KS subjects are typically tall, with small and firm testes, gynecomastia, broad hips, and sparse body hair, although a less evident presentation is also possible. KS is also characterized by a high prevalence of hypogonadism, metabolic syndrome (MetS) and cardiovascular disease. The aim of this article is to systematically review metabolic and the cardiovascular risk factors in KS patients. Hypogonadism has an important role in the pathogenesis of the changes in body composition (particularly visceral obesity) and hence of insulin resistance and MetS, but the association between KS and MetS may go beyond hypogonadism alone. From childhood, KS patients may show an increase in visceral fat with a reduction in lean body mass and an increase in glucose and impaired fat metabolism. Their increased incidence of congenital anomalies, epicardial adipose tissue, and thromboembolic disease suggests they have a higher risk of cardiovascular disease. There is conflicting evidence on the effects of testosterone therapy on body composition and metabolism.     

Extra- and intracellular free iron and the carotid body responses

The hypothesis that chelation of free iron, by decreasing reactive oxygen species (ROS), might mimic hypoxia and stimulate the carotid body was tested. We used the iron chelators, desferrioxamine (DFO, 200-400 microM) initially, and later ciclopirox olamine (CPX, 2.5-5.0 microM), on rat carotid body in vitro and measured chemosensory activity and [Ca2+]i in isolated cultured glomus cell clusters during normoxia and hypoxia. Although acute treatment of DFO might not penetrate the cell, and extracellular DFO would not influence these activities whereas CPX significantly increased chemosensory activities as well as increased [Ca2+]i in normoxia. We concluded that chelation of extracellular free iron did not alter ROS formation and oxygen sensing. Chelation of intracellular free iron and, therefore, a decrease in intracellular ROS appears to influence oxygen sensing in the carotid body.     

正常人周围神经内膜中的纤维性长间距体及神经束膜细胞的超微结构

本文报道在电镜下观察了正常人腹壁神经小分支的神经束膜细胞的超微结构,并在神经内膜间质中发现了纤维性长间距体(FLS)。 1.2～5层神经束膜细胞紧密地包绕着神经束。束膜细胞呈扁平样排列,胞质内有丰富的微丝和吞饮小泡,基膜明显而连续。紧贴其外的和神经内膜中的成纤维细胞均无基膜。两相贴的束膜细胞之间可见缝管连接和丰富的桥粒,也可见胶原纤维。神经内膜间质中胶原原纤维细,有FLS体存在;而束膜外侧的胶原原纤维较粗,未见FLS体。 2.多数FLS体与无髓神经纤维的Schwann细胞基膜相连,个别处周围为一般胶原原纤维,未见基膜;有髓神经纤维的Schwann细胞处未见FLS体。纵切面上,多数FLS体呈纺锤状,大小不等,其长轴与相邻胶原原纤维的长轴平行,有时可见两者相互延续移行。偶见FLS体呈桥样架于两Schwann细胞之间,FLS体的暗带与两侧Schwann细胞的基膜相延续。还见2～3个FLS体并为一体,但横纹错开。FLS体的斜断面近似长方形,也呈横纹样结构,与纵断面没有很大区别。FLS体的横纹周期长约133nm,暗带约53nm,主要由电子较密的颗粒状物构成;明带约80nm,由方向大致相同的微丝网构成;横纹周期中无细横纹存在。本文并对神经束膜细胞可能的作用、FLS体与基膜的关系、FLS体的横纹周期问题进行了讨论。     

Effects of ageing on the alveolar pores of Kohn and on the cytoplasmic components of alveolar type II cells in monkey lungs

The effects of ageing on the numbers of alveolar pores of Kohn and on the cytoplasmic components of alveolar type II cells were studied in monkey lungs by scanning and transmission electron microscopy. Lung tissue from 26 female and three male pigtail macaques whose ages ranged from 1 month to 31 years (life span is 35 years) was analysed. From the age of 1 month to 10 years there was a significant increase in the number of alveolar pores (r = 0.85, p less than 0. 001); however, between the ages of 14 years to 31 years there was no significant change. In seven animals ranging in age from 1 month to 4 years (mean 2.4 years) the number of pores was 5.8 +/- 3.9 (mean +/- S.D.), whereas in 10 animals aged 16 to 31 years (mean 20.3 years) the number of pores was 32.7 +/- 17.5 (mean +/- S.D.) per alveolar profile, a significant difference (p less than 0.002). In older animals (15-20 years) there was a significant decrease, both in the number of lamellar bodies per alveolar type II cell (p less than 0.01) and in the volume density of lamellar bodies to cytoplasmic volume (p less than 0.05) compared with young animals (1 month to 4.8 years). In older animals, there was also a significant increase in the volume density of a vacuole-like dilatation of the endoplasmic reticulum in alveolar type II cells (p less than 0.05) compared with young animals. These findings suggest impaired pulmonary surfactant production with aging. Both the increased number of alveolar pores and the postulated decrease of surfactant production could play a role in the pathogenesis of pulmonary emphysema.     

NMDA受体在正常大鼠颈动脉体的表达

应用免疫组织化学方法观察了离子型谷氨酸受体——NMDA受体的NR1及NR2A亚单位在正常成年雄性SD和Wistar大鼠颈动脉体的表达,并对阳性产物的表达强度进行了灰度分析及统计学处理。结果表明:正常成年SD大鼠及Wistar大鼠的颈动脉体内均存在NMDA NR1免疫反应阳性细胞,从阳性细胞的形态和分布特点判断这些阳性细胞为主细胞,两种大鼠之间无明显差异(P>0.05);而两种大鼠的颈动脉体内几乎不存在NMDA NR2A免疫反应阳性细胞。本实验的结果提示:在正常成年大鼠颈动脉体的主细胞上有NMDA受体的分布,并且该受体的二聚体构成不同于经典受体,这可能与谷氨酸在颈动脉体发挥的特殊功能有关。     

Changes in hypothalamic temperature of rats after daily exposure to heat at a fixed time

Rats were subjected to an ambient temperature (T_a) of 33°C for ca. 5 h during the last half of the dark phase for 5, 14 or 28 consecutive days (heat-exposed rats, HE), while control rats were kept at a constant T_a of 24°C. After the heat exposure schedule, the levels of hypothalamic temperature (T_hy) as an index of body core temperature in the HE were significantly lower than those of the controls for 2–4 h in the last half of the dark phase. The low levels of T_hy persisted during the specific period for 1, 3 and 6 days after the end of the 5-, 14- and 28-day heat exposure schedules, respectively. These results confirm that, in rats subjected to daily heat exposure for ca. 5 h at a fixed time per day, their T_hy falls during the period when the rats were previously exposed to heat, and suggest that the duration of the specific T_hy change observed after completing the heat exposure schedule depends on the length of the heat exposure schedule.     

Infrared-spectrometric determination of D2O in biological fluids

The determination of D₂O in biological fluids by means of infrared spectrometry was reinvestigated. When the temperature of a solution, containing D₂O in the range from natural abundance to 5 ml·1^–1 increases, its absorbance decreases and the wavenumber of maximum absorption shifts to a higher value. Both changes are linearly related to the change in temperature. Storage for 17 d in either glass or polyethylene tubes does not affect the D₂O concentration. Purification of biological fluids by vacuum-sublimation removes all substances which also absorb at the O-D vibration band and the recovery of D₂O from plasma and urine is complete. The partition ratio of D₂O between plasma water and red cell water equals unity, and the same holds for plasma water and urine water over a wide range of urine flows and osmolalities. The arterial and urinary disappearance curves of D₂O, measured over several days, both permit the calculation of the total amount of body water (V ^bw), the daily water turn-over (F) and the half-time of water in the body (t _1/2), but the data derived from arterial disappearance curves are more precise. In 16 male mongrel dogs (25–32 kg body mass) the following results were obtained:V ^bw=626±28 ml·kg^–1,F=12.0±3.2% andt _1/2=6.21±1.78 d.     

Determination of body heat storage in clothing: calorimetry versus thermometry

Two methods of estimating body heat storage were compared under differing conditions of clothing, training, and acclimation to heat. Six male subjects underwent 8 weeks of physical training [60–80% of maximal aerobic power ( ) for 30–45 min · day–, 3–4 days · week^–1 at < 25 °C dry bulb (db)] followed by 6 consecutive days of heat acclimation (45–55% for 60 min · day^–1 at 40°C db, 30% relative humidity)]. Nine other male subjects underwent corresponding periods of control observation followed by heat acclimation. Before and after each treatment, subjects walked continuously on a treadmill (1.34 m · s^–1, 2% grade) in a climatic chamber (40°C db, 30% relative humidity) for an average of 118 min (range 92–120 min) when wearing normal light combat clothing and for an average of 50 min (range 32–68 min) when wearing protective clothing resistant to nuclear, biological, and chemical agents. The heat storage was determined calorimetrically (by the balance of heat gains and losses) and thermometrically [by the conventional equations, using one or two set(s) of relative weightings for the rectal temperature (T _re) to mean skin temperature _sk of 4:1 and 4:1, 2:1 and 4:1, or 2:1 and 9:1 in thermoneutral and hot environments, respectively]. _sk was calculated from 12-site measurements, weighted according to the regional distribution of body surface area and the first eigenvectors of principal component analysis. There were only minor differences (< 5%) between the heat storage values calculated by given weighting factors forT _re and _sk, whether the individual coefficients were derived from estimates of regional surface area or principal component methodologies. When wearing normal clothing, no significant differences were found between the two estimates of heat storage (calorimetry vs thermometry with an invariant relative weighting of 4:1) in any experimental condition, with one specific exception: when wearing protective clothing, thermometry underestimated the heat storage by 24–31%. This underestimation was attenuated by using two sets of relative weightings of 2: 1 and 4: 1 or 2: 1 and 9: 1. The results suggest that when subjects wearing protective clothing are transferred from thermoneutral to hot environments, the accuracy of thermometric estimates of heat storage can be improved by using two sets of weighting factors forT _re and _sk