High Cell-Density Culture System of Hepatocytes Entrapped in a Three-Dimensional Hollow Fiber Module with Collagen Gel

Abstract: A compact three-dimensional (3D) module is needed for hepatocyte culture in order to develop an effective hybrid artificial liver system that can retain hepa-tocellular structure and differentiated functions. We treated the 3D module with collagen gel to entrap rat hepatocytes. This method yielded a high hepatocellular density (2 times 10⁷ cells/ml) over a period of 14 days and maintained the secretion of albumin and ureogenesis at the same level as the control monolayer method. The ammonia removal remained at 43% of the Day 0 value over 8 days of perfusion. Our data show that this approach may be useful for liver support therapy in an ex-tracorporeal circuit.     

NO2和LPG燃烧产物对大鼠肺脂质过氧化,胶原含量和尿HOP的影响

本研究分别观察了ＮＯ２染毒和ＬＰＧ燃烧产物自然暴露对Ｗｉｓｔａｒ雄性成年大鼠肺脂质过氧化、肺胶原含量和尿ＨＯＰ排泄的影响及其相互关系。结果发现７．５２ｍｇ／ｍ＾３的ＮＯ２对三者均有一定影响，染毒剂量不同大鼠尿ＨＯＰ排泄也有相应的变化。尿ＨＯＰ的变化早于肺胶原含量，且两者有一定的相关关系。ＬＰＧ燃烧产物暴露期间，尿ＨＯＰ含量一直高于对照组，但未见肺胶原含量的变化，８周时尿ＨＯＰ与肺脂质过氧化物之间有     

An ultrastructural study on anterior cruciate ligament reconstruction using autogenous patellar tendon grafts in dogs

An ultrastructural study was undertaken concerning morphological changes within the autografted patellar tendon (PT) after being transplanted to the anterior cruciate ligament (ACL) in mongrel dogs. After 4 weeks, the arrangements of both large and small collagen fibrils in the PT graft became disordered, and the number of inflammatory cells increased. However, the same PT grafts revealed postsurgical signs of newly-produced collagen fibrils around activated fibroblasts at 12 to 24 weeks. At 52 weeks after the transplantation, small collagen fibrils increased in both number and density, showing a remarkable morphological similarity to the collagen fibrils of normal ACL. These data indicate that the characteristics of the PT graft eventually resemble those of a normal ACL. This paper was presented in part at the Combined Meeting of the Orthopedic Research Societies of the USA, Japan and Canada in Banff, Alberta, Canada, October, 1991.     

组织工程学研究中偏光显微镜的应用

偏光显微镜是地质界用来观察晶体矿物的重要仪器。其理论基础是结晶光学，特点是即可观察结构，又可根据光学性质（折光率值不同）来判断成分。通过在研究ＮＥＣＭ和注射性胶原制作的过程中，用偏光显微镜和光镜观察同一部位的组织片，加以对比分析。因为胶原是生物体内的特殊“晶体”，故认为偏光显微镜应用在组织工程研究中，不仅开阔了观察领域，而且是重要的观测手段和方法。用偏光显微镜观察了猪骨ＥＣＭ胶原框架，以及注射性胶原制作过程中胶原变化特点。认为本方法简单不需染色，并可特异的观察到胶原的分布和走行。     

Transurethral collagen injection for treatment of stress urinary incontinence

Summary Minimally invasive treatment of urinary incontinence has become a subject of major interest in recent years. We examined the use of transurethral collagen injection for incontinence treatment. A total of 48 patients were selectet for this procedure from April 1993 to February 1997 – 26 male patients (19 post-RPX incontinence and 7 post-TUR incontinence) and 22 female patients (all after previous incontinence surgery) were treated by injection of collagen into the continence region. The whole group underwent an average of 1.8 sessions, and a mean collagen injection volume of 14.5 ml was delivered per session. Mean follow-up was 9.2 months. Of the female population, 68.2 % were cured or greatly improved. In the male population only 47.3 % of the post-RPX patients and 6/7 of the post-TUR patients benefited from the procedure. In males, treatment outcome depends on the degree of pretreatment incontinence, because all grade III incontinence patients did worse. Therefore we conclude: transurethral collagen injection is an interesting method in the treatment of urinary incontinence if proper patient selection is assured.      

Isolated human hepatocytes in culture display markedly different gene expression patterns depending on attachment status

In vitro human hepatocyte cultures are a key tool in the investigation of xenobiotic toxicity and metabolism. In most in vitro hepatocyte studies, the cells are allowed to adhere to an extracellular matrix, such as collagen. Unfortunately, the ability of freshly isolated hepatocytes to adhere to collagen varies from donor to donor. We used microarray analysis to determine what gene expression differences exist between hepatocytes in suspension and hepatocytes attached to collagen. Results from different donors showed a considerable difference in gene expression patterns between the two hepatocyte populations. In addition, we also compared the gene expression profiles of hepatocytes in culture with liver tissue. The results showed that both hepatocytes in suspension and hepatocytes attached to collagen display significant gene expression differences compared with liver tissue. Finally, we show that both populations of hepatocytes are responsive to dexamethasone and regulate some of the same genes. Overall, our results suggest that either significant gene expression changes occur in isolated hepatocytes or that suspended and attached cells represent different populations of hepatocytes found in intact livers.     

A small angle light scattering device for planar connective tissue microstructural analysis

The planar fibrous connective tissues of the body are composed of a dense extracellular network of collagen and elastin fibers embedded in a ground matrix, and thus can be thought of as biocomposites. Thus, the quantification of fiber architecture is an important step in developing an understanding of the mechanics of planar tissues in health and disease. We have used small angle light scattering (SALS) to map the gross fiber orientation of several soft membrane connective tissues. However, the device and analysis methods used in these studies required extensive manual intervention and were unsuitable for largescale fiber architectural mapping studies. We have developed an improved SALS device that allows for rapid data acquisition, automated high spatial resolution specimen positioning, and new analysis methods suitable for large-scale mapping studies. Extensive validation experiments revealed that the SALS device can accurately measure fiber orientation for up to a tissue thickness of at least 500 μm to an angular resolution of∼1^o and a spatial resolution of±254 μm. To demonstrate the new device’s capabilities, structural measurements from porcine aortic valve leaflets are presented. Results indicate that the new SALS device provides an accurate method for rapid quantification of the gross fiber structure of planar connective tissues.     

Construction of a stable nipple valve with processed dermal sheep collagen for continent ileostomy and urostomy

Summary Complications of the nipple valve system used for continent urostomy and ileostomy basically consist of incomplete (or complete lack of) adhesion of the invaginated serosal surfaces of the valve. A novel concept in fixation of the valve by means of the intussusception of a newly developed biomaterial (processed dermal sheep collagen; PDSC) was tested. The implanted PDSC is characterized by induction of fibroblast invasion and formation of new collagen fibers, initial high tensile strength, bio-inertion and (slow) biodegradation. It was implanted between the serosal surfaces of the invagination in 14 dogs without the application of the commonly used staples and synthetic mesh. Good permanent fixation was obtained in all cases after the PDSC had been sutured in place. As the observation time advanced up to 2 years, an increased amount of newly formed collagen was seen anchoring the serosal surfaces firmly together via the implanted PDSC with apparent slow degradation. In none of the test animals did complications accur. The first clinical trial was successful.This study was sponsored by the Preventie fonds     

The effects of brisk walking on markers of bone and calcium metabolism in postmenopausal women

Weight-bearing exercise has been shown to maintain or increase bone mass in younger as well as older individuals but the mechanisms by which mechanical loading affects bone metabolism are not known in detail. Twelve postmenopausal women participated in a single bout of brisk walking (50% of VO_{2 max}) for 90 minuttes. Calciotropic hormones and markers of type I collagen formation (PICP) and degradation (ICTP) were measured before the exercise, and 1, 24, and 72 hours following the exercise. Total body bone mineral content (BMC) and density (BMD) were measured by dual energy X-ray absorptiometry (DXA). Brisk walking did not induce any significant changes in the concentrations of ionized calcium, parathyroid hormone (PTH), calcitonin, or osteocalcin. A significant increase of PICP was noted 24 and 72 hours (P<0.01) after exertion and a significant decrease in the concentration of serum ICTP at 1 hour (P<0.05) was followed by an increase at 72 hours (P<0.001). There was no significant difference between the increases in the concentrations of PICP and ICTP at 72 hours. Strong inverse correlations between the basal levels of PTH and BMD (r=−0.78;P<0.01) as well as between osteocalcin and BMD (r=−0.83;P<0.01) were noticed. The changes in serum levels of bone collagen markers indicate an altered bone collagen turnover due to this moderate endurance exercise. The results also support the fact that serum levels of PTH as well as those of osteocalcin are associated with total body BMD in postmenopausal women.