双歧杆菌活菌粉的制备

用多孔淀粉吸附双歧杆菌后再喷雾干燥制备活菌粉,考察了喷雾干燥工艺过程对活菌存活率的影响,将得到的活菌粉装入肠溶胶囊制成肠溶性活菌粉胶囊,接着考察了该肠溶性活菌粉胶囊在加速贮藏条件下的贮藏稳定性.结果表明用多孔淀粉吸附双歧杆菌后,不仅在喷雾干燥过程中,而且在贮藏过程中,多孔淀粉对活菌都有保护作用.     

非晶颗粒态木薯淀粉微生物降解特性

采用光学显微分析方法,以原木薯淀粉为参照,对非晶颗粒态木薯淀粉在微生物作用下的降解过程进行了观察和研究. 结果发现,在微生物作用下,从淀粉颗粒的爆裂孔开始,沿着淀粉颗粒爆裂孔逐步深入,直至最后将淀粉颗粒完全降解,而原淀粉颗粒具有致密的结晶结构,淀粉颗粒表面没有明显的孔洞,因此在同样条件下,生物降解性能要远远低于非晶颗粒态淀粉.     

原淀粉和预处理方法对淀粉基木材胶粘剂性能的影响研究

采用不同原淀粉制备出淀粉基木材胶粘剂,通过比较发现蜡质玉米淀粉是制备淀粉基木材胶粘剂的最佳原淀粉;比较了酸解、氧化、酶解3种降粘方式对淀粉基木材胶粘剂的粘接性和流动性等性能的影响,实验表明氧化降粘具有最好的粘接性和流动性;比较了糊化对接枝共聚反应的影响,表明糊化有利于接枝共聚反应,有利于胶性能的提高.     

高交联玉米淀粉的非晶化特性

研究了以三氯氧磷为交联剂的高交联玉米淀粉的制备方法,报道了高交联玉米淀粉颗粒随反应取代度增加而逐渐非晶化的现象.采用偏光显微镜和广角X-射线衍射对其由多晶态向非晶态的渐变过程进行了研究,提出高交联玉米淀粉中存在不同于原淀粉多晶颗粒态的只含无定形结构的非晶颗粒态。对非晶颗粒态高交联玉米淀粉颗粒的粒度分布的进一步研究结果还表明,此时的淀粉颗粒发生了轻度的膨胀。     

玉米淀粉的挤压研究──淀粉在挤压过程中降解机理的研究（Ⅱ＿b）

利用ＳｅｐｈａｄｅｘＧ－２００凝胶过滤层折，碘吸附值，碘络合物吸收光谱，Ｘ－射线衍射光谱等方法对挤压淀粉进行了研究。结果表明，玉米淀粉在挤压过程中，其直链级分未发生显著变化，支链级分的降解位置位于其分子内部，挤压施加于淀粉聚合物的剪应力是挤压淀粉中直链淀粉脂肪络合物的Ｖ型结构向Ｅ型结构转换的根本原因。依据淀粉的聚集态结构，从理论上阐述了淀粉在挤压过程中降解的力化学过程，并提出淀粉降解可能为自由基过程的机理。     

非晶颗粒态马铃薯淀粉的制备方法

报道了水分散体系高温溶胀、常温碱分散体系强碱溶胀作用非晶颗粒态马铃薯淀粉的制备方法 ,采用偏光显微镜对多晶态向非晶态的变化进行了确认 ,提出在一定条件下 ,高交联马铃薯淀粉 ,可以由原淀粉多晶颗粒态制备成只含无定形结构的非晶颗粒态淀粉     

硬脂酸淀粉酯的性质

对硬脂酸淀粉酯的流变学性质和乳化稳定性进行了研究.结果表明:硬脂酸淀粉酯的粘度明显低于原淀粉,其粘度随温度的升高和剪切速率的增加而下降,取代度的增加对硬脂酸淀粉酯的粘度没有显著影响;硬脂酸淀粉酯的乳化稳定性随取代度、硬脂酸淀粉酯用量以及油水比的增加而增加,随温度的升高而降低.     

淀粉与丙烯酰胺接枝共聚物性质的研究

研究了小麦淀粉与丙烯酰胺的接枝共聚物的物理特性和结构特征,实验结果表明:该接枝共聚物在热性质上与原淀粉有明显的区别,其糊化温度比原淀粉略低,粘度热稳定性及溶解度较原淀粉均有提高。接枝共聚反应不仅发生在淀粉颗粒的表面上,而且也发生在颗粒结构的内部,但反应仅发生在淀粉的无定型区。     

γ-射线辐照甘薯淀粉对酶促水解的影响

用10至500kGy的γ-射线辐照淀粉,酶水解产生的还原糖和淀粉的碘亲和力,随剂量增加而增大;淀粉溶液的酸度和粘度随之降低。用X-衍射法研究了辐照淀粉的结晶结构,以及辐照对淀粉中微生物存活率的影响。这些结果可作为γ-辐照技术应用于无蒸煮酒精发酵的基础研究。     

高交联木薯淀粉的非糊化特性

以三氯氧磷为交联剂制备非糊化的高交联木薯淀粉,并测定了反应的取代度和布拉班德粘度曲线,研究了在沸水中受热后非糊化淀粉的颗粒形貌及粒度分布等特性．提出高交联非糊化木薯淀粉存在着不同于原淀粉颗粒的在沸水中只发生轻度有限溶胀的非糊化颗粒态     

Osseous integration in porous tantalum implants

Porous tantalum is a biomaterial that was recently introduced in orthopedics in order to overcome problems related to implant loosening. It is found to have osteoconductive, and possibly, osteoinductive properties hence useful in difficult cases with severe bone defects. So, it is of great interest to shed light on the mechanisms through which this material leads to new bone formation, after being implanted. Porous tantalum is biologically relatively inert, with restricted bonding capacity to the bone is restricted. In order to overcome this obstacle, it undergoes thermal processing in an alkaline environment. This process leads to extensive hydroxyapatite formation on its surface, and thus, to better integration of porous tantalum implants. Apart from this, new bone tissue formation occurs inside the pores of the porous tantalum after its implantation and this new bone retains the characteristics of the normal bone, that is, bone remodeling and Haversian systems formation. This finding is enhanced by the observation that porous tantalum is an appropriate substrate for osteoblast adherence, proliferation, and differentiation. Furthermore, the finding that osteoblasts derived from old women (> 60 years old) and cultivated on porous tantalum may grow faster than osteoblasts taken from younger women (< 45 years old) and cultivated on other substrates, can partially explain porous tantalum''s good performance in cases of patients with severe bone defects. In conclusion, porous tantalum''s chemical and mechanical properties are those that probably define the already noticed good performance of this material. However, further research is needed to totally clarify the mechanisms.     

内源脂类对抗性淀粉RSⅢ形成的影响

以普通玉米淀粉为试验材料 ,先制备出低脂淀粉和无脂淀粉 ,经高温压热处理后 ,分别测定它们的抗性淀粉含量 ,发现内源脂类对抗性淀粉RSⅢ的形成有显著影响 .多量脂类的存在不利于抗性淀粉的形成 ,少量脂类的存在提高了抗性淀粉产率 ,甚至略高于无脂淀粉的产率 .故对淀粉适当脱脂有利于抗性淀粉的形成 .     

Culture-expanded periosteal-derived cells exhibit osteochondrogenic potential in porous calcium phosphate ceramics in vivo.

Chick tibial periosteal cells were enzymatically disaggregated, introduced into cell culture, and subcultured. These subcultured cells were combined with porous calcium phosphate ceramics and implanted into a subcutaneous site in athymic mice as an immunocompatible host to test the in vivo osteochondrogenic potential of this composite graft. These cells eventually gave rise to bone tissue in the pores of ceramics at the heterotopic implantation sites. The process of bone formation occurred through two different mechanisms: Intramembranous bone formation occurred at the peripheral pores of ceramics early, and endochondral bone formation occurred in the central pores later. Cultured chick muscle fibroblasts of the same-aged donor as controls did not form bone or cartilage under identical conditions to those of cultured periosteal-derived cells. These results raise the possibility that composite graft of cultured periosteal-derived cells and porous ceramics can be clinically used as a bone graft substitute in situations requiring bone augmentation or regeneration.     

Heterotopic osteogenesis in porous ceramics induced by marrow cells

When untreated porous calcium phosphate ceramics were transplanted into subcutaneous (s.c.) or intramuscular (i.m.) sites, fibrovascular tissue grew in the pore region without evidence of bone formation. However, when these same ceramics were combined with syngeneic marrow cells, osteogenesis was observed inside the pore region of the implanted ceramic. The osteogenesis began on the surface of the pore region at approximately 3 weeks postimplantation by a process of intramembranous bone formation, with the de novo bone tissue observed directly interfacing with the ceramic surface. Infrequently, small isolated areas showed cartilage formation with no noticeable endochondral ossification. At 4 weeks postimplantation of the ceramic with marrow cells, the osteogenesis in the ceramic accompanied an observed increase in compressive strength, rigidity, and energy absorption of the ceramic. These results suggest that a combination of porous ceramics and marrow cells may be useful for clinical problems requiring osseous reconstruction.     

In vitro evaluation of the effect of profound haemodilution with hydroxyethyl starch 6%, modified fluid gelatin 4% and dextran 40 10% on coagulation profile measured by thromboelastography

Synthetic colloids have been implicated as a cause of coagulopathy when administered in large quantities. The effect of profound haemodilution (50%) on coagulation profile was measured in vitro by thromboelastography. Blood samples were taken from 11 ASA grade 1 patients prior to induction of anaesthesia for elective surgery. Each sample was simultaneously tested in four different preparations: undiluted blood (control sample); blood diluted with hydroxyethyl starch 6%; blood diluted with modified fluid gelatin 4%; blood diluted with dextran 40 10%. There was a significant decrease in reaction time in the preparations treated with hydroxyethyl starch 6% and modified fluid gelatin 4%, reflecting activation of initial fibrin formation. A significant increase in clot formation time was noted in the hydroxyethyl starch 6%-treated preparations. There was also a significant decrease in clot formation rate and maximum amplitude in the hydroxyethyl starch 6% group. Clot formation time, clot formation rate and maximum amplitude did not change in the modified fluid gelatin 4% group. Profound haemodilution with dextran 40 10% exerted extreme effects on the measured variables, very often resulting in a straight line on the thromboelastography profile.     

Glove powder promotes adhesion formation and facilitates tumour cell adhesion and growth

BACKGROUND: The presence of foreign material in the abdominal cavity irritates the peritoneal surface, leading to an inflammatory response. This defensive mechanism can provoke adhesion formation. The same peritoneal defence cascade is thought to play a role in the process of intra-abdominal tumour recurrence. The aim of this study was to evaluate whether glove powder produced peritoneal adhesions in a rat adhesion model and whether it promoted intra-abdominal tumour recurrence in a rat tumour cell adhesion and growth model. METHODS: A reproducible model that allowed semiquantitative scoring of adhesion formation or tumour load was used in three different groups of rats. One group was treated by intra-abdominal application of powder obtained from starch-powdered gloves, one by application of pure starch and in one group no powder was used. RESULTS: Application of glove powder or pure starch on minimally and severely traumatized peritoneum gave rise to significantly greater adhesion formation and intra-abdominal tumour load than peritoneal trauma alone (both P < 0.001). CONCLUSION: Starch-induced peritoneal trauma leads not only to more adhesion formation but also to increased adhesion and growth of tumour cells. Since good powder-free alternatives are available there is no longer any justification for the use of powdered gloves during intra-abdominal surgery.     

The efficacy of BMP-2 to induce bone ingrowth in a total hip replacement model

The purpose of this canine total hip arthroplasty (THA) study was fourfold: (1) to quantify the efficacy of rhBMP-2 in a carrier (alphaBSM) versus alphaBSM alone, and versus untreated controls to induce bone formation across a defect between a porous acetabular component and host bone; (2) to quantify whether rhBMP-2/alphaBSM improves bone growth into the porous surface beneath that defect; (3) to quantify the efficacy of rhBMP-2/alphaBSM in inducing bone ingrowth into the porous layer at points of intimate bone-implant contact; and (4) to determine whether rhBMP-2/alphaBSM placed in the lateral uncovered aspect of the porous acetabular component promotes de novo bone formation. Fifteen dogs were sacrificed 12 weeks after uncemented THA. Five dogs received rhBMP-2/alphaBSM, five dogs received alphaBSM, and five dogs were controls. In contrast to the controls in which no bone filled the defect, the rhBMP-2/alphaBSM induced defect filling and full bone formation in the underlying porous coating. The alphaBSM produced an intermediary response. However, no increase in new bone formation occurred at sites of intimate bone porous surface contact. Recombinant bone morphogenetic protein-2/alphaBSM promoted defect filling and bone ingrowth into the porous coating beneath the defect region, both of potential value in future total joint replacement surgery.     

Intramedullary bone repair and ingrowth into porous coated implants in the adult chicken: a histologic study and biochemical analysis of collagens

A new model was developed to study the histologic and biochemical events during intramedullary bone repair and ingrowth into porous coated implants. Adult chickens were used because of the availability of specific antibody probes. Repair in the metaphysis and diaphysis were compared. Entering through a medial arthrotomy, the distal tibiotarsus was reamed and either implanted with a double-ended porous coated rod or allowed to heal without implantation of a rod. Specimens analyzed histologically at 7, 14, 21, and 70 days postoperatively revealed direct formation of bone by osteoblasts with no evidence of a cartilaginous phase. At 70 days bony ingrowth was observed deep within the porous surface. Analysis of collagens with sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated that the synthesis of type I collagen predominated. Biosynthetic data coupled with quantitative immunologic analyses using antibodies to type II and type X collagen showed that neither of these two collagen types, which are characteristic of cartilage undergoing endochondral ossification, were produced during intramedullary bone repair. These results establish that the adult chicken is capable of bony ingrowth into porous coated implants and that this process is through direct bone deposition by osteoblasts without a cartilaginous intermediate.     

Differences in neointima formation between impervious and porous polytetrafluoroethylene vascular patch material

The aim of this study was to compare the neointima formation and blood loss of an impervious ePTFE with those of the porous ePTFE patch. Ten mongrel dogs were selected for the study. Both the impervious and porous ePTFE patches were implanted into the common iliac arteries in each dog. The blood loss of each patch was recorded and the patches were explanted 30-60 days later for microscopic analysis. The arteries with either the impervious or the porous ePTFE patch were all patent at the end of the study. The impervious ePTFE patch had a significant reduction in blood loss when compared with the porous ePTFE patch (p = 0.04). The neointima covering both patches showed no statistically significant difference in its thickness or in its cellular composition. It has been speculated that wall porosity is essential for tissue ingrowth, endothelial cell proliferation, and neointima formation. In this study, the impervious ePTFE patch did not inhibit neointima formation. Our study shows that graft porosity does not improve neointima formation or patency. Neointimization of the impervious ePTFE patch is the result of pannus ingrowth and deposition of circulating blood elements. There is a statistically significant reduction in blood loss (p = 0.04) with impervious ePTFE patch, compared with that of the porous ePTFE patch.