瘦素与脂肪生成

瘦素是一种由肥胖基因编码、主要由脂肪组织合成和分泌的蛋白质,通过与其受体结合而发挥多种生物学效应.许多研究发现瘦素能减少脂肪蓄积,但其发挥作用的机制还不是很清楚.本文就瘦素对脂肪生成的作用,尤其是瘦素对前脂肪细胞增殖与分化的影响进行综述.     

瘦素与胃肠运动

瘦素是由肥胖基因编码、脂肪细胞分泌的一种蛋白质类激素,在调节摄食、体重、能量消耗和神经内分泌方面发挥着重要的作用.研究证实,瘦素可以改变胃肠神经肌肉的反应性,从而调节胃排空及肠动力.表明瘦素是与胃肠的生理功能及胃肠疾病密切相关的一种新的胃肠激素.本文就瘦素与胃肠运动的关系进行简要综述.     

瘦素与胆结石形成的关系

瘦素(Leptin)是由脂肪细胞分泌的一种调节机体能量平衡的激素.胆结石病人血中瘦素的浓度较高,瘦素可以通过调节脂质代谢,影响胆囊的收缩性,改变胆汁蛋白的成分等机制影响结石的形成.本文就对瘦素在胆结石形成中的作用的研究进展做一综述.     

瘦素在乳腺癌发病中的作用

瘦素是一种由肥胖基因(ob基因)编码表达的小分子蛋白,在调控机体的摄食行为和脂肪代谢方面具有重要作用.近来大量研究发现瘦素在体外可促进乳腺细胞转化、癌细胞增生并促进血管生成.这表明瘦素在乳腺癌的发生发展中可能起重要作用,但具体机制尚未阐明.本文主要从体外实验、动物试验和乳腺癌病理组织研究3方面对瘦素在乳腺癌发病中的作用的近年相关研究进展进行综述.     

瘦素在乳腺癌发病中的作用

瘦素是一种由肥胖基因(ob基因)编码表达的小分子蛋白,在调控机体的摄食行为和脂肪代谢方面具有重要作用.近来大量研究发现瘦素在体外可促进乳腺细胞转化、癌细胞增生并促进血管生成.这表明瘦素在乳腺癌的发生发展中可能起重要作用,但具体机制尚未阐明.本文主要从体外实验、动物试验和乳腺癌病理组织研究3方面对瘦素在乳腺癌发病中的作用的近年相关研究进展进行综述.     

瘦素在乳腺癌发病中的作用

瘦素是一种由肥胖基因(ob基因)编码表达的小分子蛋白,在调控机体的摄食行为和脂肪代谢方面具有重要作用.近来大量研究发现瘦素在体外可促进乳腺细胞转化、癌细胞增生并促进血管生成.这表明瘦素在乳腺癌的发生发展中可能起重要作用,但具体机制尚未阐明.本文主要从体外实验、动物试验和乳腺癌病理组织研究3方面对瘦素在乳腺癌发病中的作用的近年相关研究进展进行综述.     

瘦素与骨关节炎

瘦素是一种由肥胖基因编码的一种分泌型蛋白质,分子质量约为16kDa,主要由白色脂肪组织产生。它具有细胞因子和激素的双重功能,起着调节能量代谢、炎症反应、免疫反应、神经内分泌及血管生成的作用等。本文就瘦素在骨关节炎中作用的研究现状及争论作一综述。     

痩素对骨质疏松症效应的研究进展

瘦素作为一种内分泌激素,通过中枢和外周两种途径调节骨代谢.瘦素的中枢效应可能是通过下丘脑、交感神经系统以及β受体而最终引起骨量减少,瘦素的外周效应可能是通过骨髓基质细胞,骨化细胞和破骨细胞3个方面起作用并最终引起骨量增加.瘦素对骨代谢的整体作用可能取决于血清瘦素的水平及血脑屏障的通透性.     

瘦素与肠黏膜屏障

瘦素是一种主要由脂肪细胞分泌的多肽类激素,在机体具有广泛的生物学效应,具有调节能量代谢、生长发育、免疫反应、促进损伤修复等作用。近年来,对肠道瘦素及其受体研究的不断深入研究,证明瘦素作为一种新的胃肠道激素,在调节胃肠功能、维护肠黏膜屏障方面具有重要的生理功能。     

瘦素对损伤器官的保护作用

瘦素是一种主要由脂肪组织合成、分泌的多肽类激素,在调节体重和代谢、内分泌反应中具有重要作用,近来发现它是多种器官抵抗损伤的保护因素.本文对其保护作用及可能的机制进行综述.     

睾丸CR16与精子发生

精子发生是依靠各种激素(FSH、LH、T、17β雌二醇)、细胞因子和基因调节的复杂调控过程。基因调控在精子发生中的研究已逐渐成为热点,已发现的与精子发生相关的基因,如AYZ、DAZ、YRRM、NOSTRIN等。但目前关于CR16在男性生殖方面的报道尚不多见,其在精子发生中的作用机制并不十分清楚,本文主要从支持细胞形成血睾屏障角度,对CR16在男性生殖系统精子发生中的研究做一综述。     

Persistent organic pollutants and male reproductive health

Environmental contaminants such as persistent organic pollutants （POPs） are man-made bioaccumulative compounds with long half-lives that are found throughout the world as a result of heavy use in a variety of consumer products during the twentieth century. Wildlife and animal studies have long suggested adverse effects of exposure to these compounds on human reproductive health, which, according to the endocrine disrupter hypothesis, are ascribed to the compounds＇ potential to interfere with endocrine signaling, especially when exposure occurs during certain phases of fetal and childhood development. An extensive number of epidemiological studies have addressed the possible effects of exposure to POPs on male reproductive health, but the results are conflicting. Thus far, most studies have focused on investigating exposure and the different reproductive health outcomes during adulthood. Some studies have addressed the potential harmful effects of fetal exposure with respect to malformations at birth and/ or reproductive development, whereas only a few studies have been able to evaluate whether intrauterine exposure to POPs has long-term consequences for male reproductive health with measurable effects on semen quality markers and reproductive hormone levels in adulthood. Humans are not exposed to a single compound at a time, but rather, to a variety of different substances with potential divergent hormonal effects. Hence, how to best analyze epidemiological data on combined exposures remains a significant challenge. This review on POPs will focus on current knowledge regarding the potential effects of exposure to POPs during fetal and childhood life and during adulthood on male reproductive health, including a critical revision of the endocrine disruption hypothesis, a comment on pubertal development as part of reproductive development and a comment on how to account for combined exposures in epidemiological research.     

Decrease in bone mineral density and muscle mass after femoral neck fracture: A quantitative computed tomography study in 25 patients

We performed a prospective, longitudinal, quantitative computed tomography (QCT) study of bone mineral density (BMD), cortical bone volume, bone mass and muscle volume in 25 patients who were operated on with osteosynthesis because of a displaced femoral neck fracture. Both legs were scanned within 3 days after the fracture, and 3 and 6 months after the operation. The measurements were performed by a computer tomograph equipped for bone mineral densitometry.

We found some side differences among the patients at the time of fracture, but none of the differences was statistically significant. After 6 months, we found reductions in BMD in the distal femur and proximal tibia on the fractured side of 11 % and 19%, respectively, as well as a reduction in BMD of 7% in the proximal tibia on the uninjured side. We found no changes in cortical bone mass, either on the fractured femur or on the uninjured femur. The muscles of the thigh showed a loss of 9% on the fractured side, but a gain of 12% on the uninjured side.

The findings of a bone loss in the distal femur and proximal tibia of the fractured leg and in the proximal tibia of the healthy leg, but no cortical bone loss in the middle femur on any side 6 months after the fracture, indicate that the cancellous bone is more sensitive to osteopenia. Moreover, this bone loss is interpreted as mainly a posttraumatic effect, since we also found a decrease in bone mineral on the uninjured side, despite a gain in muscle volume on that side, an overuse which was not sufficient to counteract the posttraumatic effect on the bone of the uninjured side.     

Prospective randomized trial of early initiation and hospital discharge on a liquid diet following elective intestinal surgery

Length of hospital stay after elective intestinal surgery may be related to patient tolerance of a diet. We hypothesized that early initiation and discharge home on a clear liquid diet would decrease the length of hospital stay without increasing morbidity. The aim of this study was to determine if early initiation and discharge on a clear liquid diet decreases the length of hospital stay and is safe. Forty-four patients were randomly assigned to either a standard diet or a clear liquid diet. A standard diet (n = 17) was begun after the passage of flatus or stool, and consisted of clear liquids to a volume of approximately 750 ml, then three solid meals, and discharge thereafter. Patients randomized to a clear liquid diet (n -27) received 30 ml/hr of clear liquids on postoperative day 2, unlimited clear liquids on postoperative day 3, and were dismissed on a clear liquid diet on postoperative day 4. All patients were followed by a daily telephone call and clinic visit. The primary outcome variable was length of hospital stay. The incidence of postoperative intestinal-related sequelae, complications, and readmission rates did not differ between groups. Posl-discharge intestinal symptoms were common in both groups but tended to resolve faster in the patients on a standard diet. The length of hospital stay was decreased in the patients on a clear liquid diet compared to those on a standard diet (6.1 ±1.1 days vs. 4.4 ±0.2 days; P = 0.09), but total hospital costs did not differ. Early initiation and hospital discharge on a clear liquid diet after elective intestinal surgery decreases the length of hospital stay and is safe. Presented at the Fortieth Annual Meeting of The Soeiety for Surgery of the Mimentary Tract, Orlando, Fla., May 16–19. 1999.     

Analysis of Flow Patterns in a Ventricular Assist Device: A Comparative Study of Particle Image Velocimetry and Computational Fluid Dynamics

Abstract:  In order to develop a diaphragm-type ventricular assist device (VAD), we studied the flow field change following structural modifications. We devised a center flow-type pump by putting a small projection on the center of the housing and/or diaphragm to provide a center in the flow field, and examined the following four types of VADs: N type without a projection, D type with a projection on the diaphragm, H type with a projection on the housing, and DH type with projections on both the diaphragm and housing. Computational fluid dynamics (CFD) was used for flow simulation. Particle image velocimetry (PIV) was also used to verify the reliability of the CFD method and to determine how the flow field changes in the presence of a projection. The results of the PIV and CFD analyses were comparable. The placement of a projection on the housing was most effective in rectifying the flow field.     

Antiatherogenic effect of abdominoplasty in patients with anterior abdominal wall deformity and obesity

The impact on a lipids metabolism of a certain volume of fat tissue extraction from organism was investigated. With that objective there was determined the lipids content in a blood serum before and on a 14th day after abdominoplasty. In 73 patients (the main group) surgical interventions were performed on the organs of abdominal cavity, small pelvis and anterior abdominal wall with a simultant abdominoplasty, in 59 patients (a comparison group) abdominoplasty was not performed. The lipids metabolism desorders was observed in both groups of patients. The results of operations, conducted with a simultant extraction of a fat tissue were characteristic for positive dynamics of the lipids spectre in the blood. A normalizing impact on the blood serum lipids was caused by a triglyceride depot volume reduction, which promotes a catabolism processes strengthening in atherogenic lipoproteins and stabilizes a nonesterified fat acids concentration on optimal level. The data obtained witness, that abdominoplasty conduction secures antiatherogenic affect in patients, suffering obesity.     

The effect of cadmium on the formation and properties of hydroxyapatite In vitro and its relation to cadmium toxicity in the skeletal system

In order to understand the biological action of cadmium (Cd) in inducing bone pathologies, the effect of Cd on the formation, structure, and properties of hydroxyapatite (HA) in vitro was investigated using three biologically relevant test systems: (1) direct precipitation of HA with no precursor phase; (2) transformation of amorphous calcium phosphate (ACP) to crystalline HA; and (3) growth of HA seed crystals. Cd-containing HA was prepared by transforming ACP to HA in the presence of Cd at a pH of 10; Cd/Ca ratios of 0.05, 0.10, and 0.20 were obtained. Infrared and x-ray diffraction analyses were performed on the Cd-HA samples, and measurements were made of Cd adsorption on HA and of the dissolution characteristics of Cd-containing HA. Cd incorporation in HA introduced little strain in the lattice but resulted in a decreasing C-axis spacing and a corresponding crystal size decrease in the C-axis direction. Cd incorporation had a nominal effect on HA dissolution. Cd had an inhibitory effect on HA formation kinetics in all three test systems. Infrared spectroscopy of Cd-HA showed a complex series of small changes in the spectra as a function of Cd concentration resulting from some distortion in the crystal perfection and symmetry. The interference of Cd with mineralization can be partially explained by its inhibitory effect on HA nucleation and growth in addition to any cellular involvement. Furthermore, Cd probably has little effect on bone mineral dissolution. Our results explain the Cd incorporation reported in bone.     

Anorectal impalement in a pediatric patient with transanal evisceration of small bowel

Rectal injuries in the pediatric population are most often attributed to accidental falls on offending objects, sexual abuse, or blunt trauma. Anorectal impalement is a rare injury, and as a result, specific knowledge or experience on the treatment of this type of injury in children is sparse. The extent of injury is often difficult to assess. Mostly, therapeutical decisions are based on general knowledge in adults. We present a case of accidental anorectal impalement in a child by a fall on the handle of a toilet brush. The handle caused an anterior rupture of the intraperitoneal part of the rectum with subsequent transanal evisceration of several loops of small bowel.     

Albumin Adsorption and Retention on C18-Alkyl-Derivatized Polyurethane Vascular Grafts

The short-term albumin affinity and thrombo-resistance of a polyether polyurethane vascular graft have been improved. The method is based on the C18 alkylation of the polymer. Thrombus formation by a planimetric technique and albumin retention on wire-reinforced polyurethane tubes, both C18 alkylated and untreated, were measured in short-term (4-h) exposure at femoral arterial sites in the dog. 125I-Albumin was preabsorbed on tubes and then exposed to blood for successive 2-h periods. Albumin uptake on alkylated tubes prior to blood exposure and retention following 2 h of blood exposure were significantly greater than on controls. Following a fast desorption phase in blood, the remaining albumin was more slowly desorbed from alkylated than from control tubes. Reincubation with albumin and blood reexposure produced a similar tendency, suggesting blood conditioning does not reduce the albumin affinity-enhancing property of C18 alkylation in the short term. Blood-preconditioning experiments suggested endogenous albumin has a high affinity for the C18-alkylated surface. Scanning electron microscopic examination showed thrombus and platelet densities were higher on control than on alkylated surfaces. These results suggest in vivo albumin affinity is increased for C18-alkylated polyurethane, which may be linked to decreased thrombus formation on these surfaces.     

Rhythmic dentinogenesis in the rabbit incisor: Allometric aspects

Summary We have described differences in the aspects of biological rhythms for calcium and sulfur deposition on the labial and lingual sides of the growing rabbit incisor, where growth occurs along a spiral axis. The calcium oscillations appear to be smoother on the labial side than on the lingual side. The lingual side is characterized by high-frequency rhythms with high amplitudes which possess the greatest percent of the power (Fourier analysis). These observations also reflect a difference in behavior of the mean Ca concentration across the labial and lingual sides. Sulfur rhythms on the labial side have higher amplitudes than those on the lingual side, but systematic differences in distribution of power between high and low frequencies is not as pronounced as in the case of Ca. The differences in Ca rhythms reflect differences in the growth rates of incisors on either side of the spiral axis. The labial side grows slightly faster than the lingual side, and its odontoblasts secrete Ca along the spiral axis and toward the pulp cavity at the same time. Thus the resultant direction of growth is more nearly opposite the extension of the occlusal end on the labial side, and Ca is consequently deposited over a wider area relative to that on the lingual surfaces. On the lingual side, Ca is deposited within a more limited area, and growth must therefore be continuous at high frequencies. The distribution of Ca on both sides of the tooth reflects these differences in growth rate and periodicity in two ways. First, given a unit area of tooth, the calcium concentration on the labial side is less than that of the lingual side. Second, whereas the calcium concentration on the labial side declines rapidly from the enamel-dentin junction to the pulp cavity, it is uniformly high across the lingual side because its growth is more continuous at high frequencies.