Effect of flow configuration and membrane characteristics on membrane fouling in a novel multicoaxial hollow-fiber bioartificial liver.

A novel "multicoaxial hollow fiber bioreactor" has been developed consisting of four concentric tubes, the two innermost tubes are called hollow fibers. Bioartificial livers are created by culturing liver progenitors in the space between the two innermost hollow fibers and with culture media contained in the two compartments (intracapillary and extracapillary) sandwiching the cell compartment. The outermost compartment is used for gas exchange. A hydrodynamic model has recently been established to predict the optimum hydraulic permeability and bioreactor operational parameters to create the physicochemical environment found in the liver acinus. However, perfusion with serum-free hormonally-defined media and inoculation of cells introduces membrane fouling into the equation, and this parameter must be incorporated into the model. Using commercially available semipermeable hollow fibers (1 mm [0.65 microm pores] and 3 mm [0.1 microm pores] outer diameters [o.d]), the primary cause of resistance is the middle hollow fiber. Preliminary studies using bioreactors inoculated with isolated rat hepatocytes and perfused with serum-containing culture media demonstrated that the middle hollow fiber is the primary site of fouling, and this fouling ultimately causes cell mortality by blocking the transfer of nutrients. Experiments were performed to determine the best commercially available middle hollow fiber for construction of bioreactors and two 3-mm outer-diameter middle hollow fibers were compared: polypropylene and polysulfone, with 0.2 microm and 0.1 microm pore sizes, respectively. Dead-ended and cross flow configurations were compared for their effectiveness at reducing membrane fouling in the middle hollow fiber by determining the change in resistance with time. The results demonstrate that the 0.2-microm pore size polypropylene hollow fiber is the best choice for construction of the multicoaxial hollow-fiber bioreactor, and that cross flow results in two orders of magnitude lower resistance than dead-ended flow after 36 h.

Rapid improvement of icterus and pruritus by the oral administration of colestimide in two cases of drug-induced hepatitis.

We report two cases of drug-induced hepatitis refractory to therapy of ursodeoxycholic acid and prednisolone, who were relieved of icterus and pruritus immediately by the oral administration of colestimide. Their liver dysfunction was not improved, by withdrawal of causative drugs or by treatment with prednisolone and ursodeoxycholic acid. Colestimide (3.0 g/day), a strong basic anion-exchange resin, was orally taken before breakfast and evening meal, leading to rapid and complete relief of icterus and pruritus. These cases suggested that colestimide would be useful for patients with cholestasis in drug-induced hepatitis, because this agent has few side effects and it is easy to take.

Comparison of the mechanical properties of polyglycolide-trimethylene carbonate (Maxon) and polydioxanone sutures (PDS2) used for flexor tendon repair and active mobilization.

Thirty-six canine flexor digitorum profundus tendons were repaired using 5-0 polyglycolide-trimethylene carbonate monofilament (Maxon) or polydioxanone monofilament (PDS2). All the tendons healed without rupture or formation of gaps of more than 2 mm. Mechanically, all tendon repairs had sufficient tensile strength to enable active mobilization. Polyglycolide-trimethylene carbonate (Maxon) repairs were initially superior in gap and ultimate strength to polydioxanone (PDS2) repairs. However, the gap and ultimate tensile strength of polyglycolide-trimethylene carbonate (Maxon) repairs had decreased significantly at day 14, whereas polydioxanone (PDS2) repairs maintained their strength throughout the 28-day observation period.

Comparison of mechanical properties of polyvinylidene fluoride and polypropylene monofilament sutures used for flexor tendon repair.

We performed an experimental study to evaluate the mechanical properties of polyvinylidene fluoride sutures and to compare their use with that of standard polypropylene sutures for the circumferential, epitendinous suture of a flexor tendon repair. Polyvinylidene fluoride sutures had a smaller suture diameter, a greater knot pull strength and less delayed extension when under creep testing, than polypropylene sutures. Tendons repaired using polyvinylidene fluoride sutures had significantly greater gap and breaking strengths than those repaired using polypropylene sutures.

[Effects of the gene transfer into sperm mediated by liposomes on sperm motility and fertilization in vitro].

To clarify the problems of gene transfer in the fertility clinic, we investigated the safety and effectiveness of the gene transfer of mouse sperm using the lipofection method. We used the pCAGGS-lacZ plasmid connected with cytomegarovirus enhancer/chicken beta-actin promoter as an adventitious gene. After incubation of the DNA-liposome complex and mouse sperm of epididymis in the medium, we investigated the sperm motility after gene transfer, in vitro fertilization rate of the gene transferred sperm, and gene expression of the fertilized ovum and fetus. Sperm motility was lowered significantly with the increase in DNA density. The fertilization rate for in vitro fertilization was lowered significantly with the increase in DNA density. Gene expression was observed in some of the fertilized ova. In the fetus 12.5 days after embryo transfer, gene transfer was confirmed by the PCR method, but we could not find gene expression by X-gal staining. We proved that the sperm with a gene transferred by the lipofection method could fertilize the ovum and transfer adventitious gene to ova. We speculate that sperm motility and fertility rate were lowered because the introduction of DNA and the DNA-liposome complex destroyed parts of the cell. Development of a sperm fractionation method for DNA transfer and establishment of a method for effective and safe DNA transfer are awaited.

[Relation between anterior displacement of the temporomandibular joint disc and size of the condyle].

To elucidate the cause of anterior displacement of the disc, we evaluated the relation between anterior displacement and the size of the condyle from MR images in 301 patients (602 TMJs) with clinical diagnosis of internal derangement. We found that the size of condyles with anterior displacement of the disc was significantly smaller than that of condyles without anterior displacement. This result suggests that small condyles may give rise to anterior displacement of the disc.

Expression and secretion of an Arthrobacter dextranase in the oral bacterium Streptococcus gordonii.

We have constructed a plasmid to express and secrete dextranase in the oral bacterium Streptococcus gordonii. The dextranase gene from Arthrobacter sp. strain CB-8 was linked to a promoter and a DNA sequence encoding the signal peptide of Streptococcus downei glucosyltransferase I (gtfI) followed by the Escherichia coli rrnBt1t2 terminator and inserted in the shuttle vector pVA838. S. gordonii transformed with this plasmid (pMNK-4) expressed and secreted mature Arthrobacter dextranase. The transformant was found to repress the firm adherence of water-insoluble glucan in a coculture experiment with cariogenic bacteria, Streptococcus sobrinus, in the presence of sucrose. Such genetically engineered oral bacteria could provide a therapy to prevent dental caries.

Identification of whale species by thin-layer isoelectric focusing of sarcoplasmic proteins.

Thin-layer isoelectric focusing was applied to the identification of whale (Cetacea) species by using water-soluble sarcoplasmic proteins of skeletal muscles. Twenty-eight samples consisting of 4 species (10 samples) of baleen whales (Mysticeti) and 8 species (18 samples) of toothed whales (Odontoceti) were analyzed. Each sample (approximately 1 g) was electrophoresed with Ampholine PAGplate, pH 3.5-9.5. The electrophoretic profiles were species-specific on the 4 toothed whale species that did not have a marked intra-species difference, and all 4 baleen whale species. However, the profiles were not specific on the 4 other dolphin species, even though they were discriminable from the other 4 toothed whale species. Numerical values of pIs and relative peak heights were obtained by densitometric analysis of the isoelectro-focused protein bands. The bands were also species-specific for the 8 toothed whale species mentioned. The values may be applicable to species identification without the need for a standard sample, which may not be readily obtainable. Experiments on test samples of minke and sel whales showed that bloodletting with ice water made the densities of isoelectro-focused bands thinner, although species identification was still possible by using the inside part of muscles. Heat treatment at below 60 degrees C for 10 min caused little denaturation; at higher temperatures the protein bands were diminished in a temperature-dependent fashion. Therefore, the present isoelectric focusing analysis should be applicable to small samples of whale meat, excluding several species of dolphins.

Biomechanical and histologic characteristics of canine flexor tendon repair using early postoperative mobilization.

The purpose of this experimental study was to evaluate the mechanical and histologic healing of flexor tendon repairs using an early active motion protocol. Three different flexor tendon repair techniques in zone II were used. Forty-seven lacerated canine flexor profundus tendons from 25 dogs were repaired and evaluated at 5, 10, and 21 days after surgery. Eight of 9 Kessler repairs ruptured at days 5 and 10. None of the 19 Savage repairs or the 19 dorsal tendon splint repairs ruptured; 3 of 19 dorsal tendon splint repairs failed owing to adhesions. Smooth tendon gliding was obtained in all specimens in which repair was successful. The gap strength values for both the Savage and dorsal tendon splint repairs improved significantly for day-21 specimens compared to day-5 or day-10 specimens. The ultimate tensile strength showed no reduction during the 3-week period of tendon healing for both repairs. Histologically, there was evidence of progressive healing without surrounding adhesions. The improved suture techniques have the potential to withstand the stress produced by active digital motion protocols.

Effect of absorbable polydioxanone flexor tendon repair and restricted active mobilization in a canine model.

We performed an experimental study to evaluate the mechanical and histologic healing process of flexor tendon repair using absorbable polydioxanone monofilament followed by active mobilization. Sixty-four canine flexor digitorum profundus tendons were repaired using polydioxanone monofilament or control braided polyester. Animals were evaluated 7, 14, 28, and 42 days after surgery with 12 day 0 control tendons. All repaired tendons healed without rupture or gap formation. Mechanically, all specimens had adequate tensile strength enabling active mobilization. The tendons that were repaired using braided polyester healed without initial tensile depression; however, the ultimate tensile strength values of polydioxanone specimens showed a significant decrease at day 14. Histologically, an inflammatory response was observed around the polydioxanone monofilament; this reaction increased from day 14 to day 42. However, the inflammatory response did not cause large adhesions or large tendon callus formation. This method of using absorbable suture material for tendon repair has the potential for use in the clinical setting.