Development and evaluation of a new composite Laserskin graft

BACKGROUND: Tremendous effort has been made to improve the graft take rate of cultured epidermal autograph. The purpose of this study is to develop and evaluate a new composite Laserskin graft (CLSG) as a human skin substitute for wound resurfacing. METHODS: The seeding efficacy of cultured keratinocytes on plain Laserskin was compared with the 3T3 cell-seeded Laserskin and allogenic fibroblast-populated Laserskin. Three different types of CLSG, 2 cm in diameter each, were prepared and tested in rats. Type A CLSG consisted of proliferative allogenic rat fibroblasts on both sides of the Laserskin with autologous keratinocytes also on the upper side. Fibroblasts and keratinocytes were seeded only on the upper side of the Laserskin in type B CLSG. Keratinocytes alone were seeded on plain Laserskin in type C CLSG. Type B CLSG consisting of autologous keratinocytes and autologous dermal fibroblasts was tested on five selected wounds (5x5 cm each) of a patient with full-thickness burn. In another burn patient, type B CLSG consisting of autologous keratinocytes and allogenic dermal fibroblasts was grafted onto three wounds (5x5 cm each). RESULTS: The seeding efficacy of human keratinocytes on plain Laserskin increased from 75% to 95% when proliferative allogenic fibroblasts were grown as a feeder layer on the Laserskin. The seeding efficacy of rat keratinocytes increased from 36% to 88% in the presence of a proliferative allogenic fibroblast feeder layer, whereas human/rat keratinocytes had respective seeding efficacy of 98%/91% on Laserskin preseeded with mitomycin C-treated 3T3 cells. Skin biopsies of grafted type A CLSG on day 14 after grafting showed complete epithelialization without severe inflammation in 16 of 20 (80%) grafted surgical wounds in rats. There were eight (40%) and seven (35%) "takes" of the CLSG in types B and C, respectively. The infection rate in type B CLSG was two (10%). There was one (5%) infection in types A and C. The respective take rates on the two patients grafted with type B CLSG were 60% and 100%. CONCLUSION: The animal experiment and the preliminary clinical data showed that the CSLGs consisting of autologous keratinocytes and of autologous/allogenic fibroblasts are good human skin substitutes in terms of durability, biocompatibility, high seeding efficacy for keratinocytes, high graft take rate, and low infection rate.     

An in vivo model of femtosecond laser intrastromal refractive surgery

BACKGROUND AND OBJECTIVE: To develop an animal model for evaluation of femtosecond laser intrastromal refractive surgery. METHODS: Intrastromal photodisruption was performed in New Zealand Albino rabbits using a femtosecond laser system. This surgical pattern consisted of a 100 microm-tick pyramid of laser pulses starting 180 microm below the corneal surface. Animals underwent serial slit lamp examinations and corneal thickness measurements at 1,3,7,14, and 28 days, then monthly up to 1 year. RESULTS: Approximately 70 microm of central corneal thinning were seen at 1 week, remaining stable up to 7 months. CONCLUSIONS: Intrastromal photodisruption with femtosecond lasers produced consistent changes in corneal thickness without loss of corneal transparency. These changes were more stable than those produced with excimer laser procedures in a similar animal model.     

Antiplatelet effect of amlodipine: a possible mechanism through a nitric oxide-mediated process.

The effect of amlodipine, a novel calcium channel blocker of the dihydropyridine type, on rabbit platelet aggregation, and the possible antiaggregatory mechanisms of amlodipine, especially on the nitric oxide (NO) guanosine 3',5'-cyclic monophosphate (cyclic GMP)-mediated pathway, were investigated. Other effects of amlodipine on thromboxane B2 (TXB2) formation in platelets also were examined. Amlodipine concentration-dependently inhibited rabbit platelet aggregation induced by collagen (10 microg/mL) or thrombin (0.1 U/mL) with an IC50 range of 32-69 microM. Along with this inhibition, our results also demonstrated that in the presence of L-arginine (100 IM), amlodipine (50 microM) increased nitric oxide synthetase (NOS) activity (from the resting activity of 2.05+/-0.36 to 7.11+/-0.95 pmol/mg protein/min) and NO release (by 80%), accompanied by an elevation of the cyclic GMP level (from the resting platelet level of 1.27+/-0.12 to 6.21+/-0.55 pmol/10(9) platelets) induced by collagen (10 microg/mL). However, the antiaggregatory effect of amlodipine (50 microM) could be attenuated significantly by oxyhemoglobin (5 microM), a NO scavenger, or N(G)-nitro-L-arginine methyl ester (100 microM), a specific NOS inhibitor. In addition, the TXB2 production in platelets induced by collagen or thrombin was concentration-dependently inhibited by amlodipine. Therefore, we propose that the antiaggregatory mechanisms of amlodipine might be mediated, in part, by a NO-cyclic GMP process accompanied by the inhibition of TXB2 formation in platelets.     

Different pH Dependency of Mitomycin C Activity in Monolayer and Three-Dimensional Cultures

Purpose. Previous studies by other investigators have shown an enhancement of mitomycin C (MMC) activity at acidic extracellular pH (pH_e) in monolayer cultures of human cells. The goal of the present study was to determine if the efficacy of intravesical MMC therapy in patients treated for superficial bladder cancer can be enhanced by using acidified dosing solutions. We evaluated (a) the effect of pH_e on MMC activity in patient bladder tumors in vitro, and (b) the pH dependency of MMC activity in 2-dimensional monolayer and 3-dimensional multilayer cultures of human bladder RT4 tumor cells. Methods. Patient bladder tumors were maintained as 3-dimensional histocultures. RT4 cells were harvested and maintained as monolayer cultures or as 3-dimensional cell pellets on a collagen gel matrix. The cell pellets were 300–450 cell layers and 4,000–5,000 µm in diameter. Tumors or cells were incubated for 2 hr with MMC-containing media at pH_eof 5, 6, and 7.4. The drug effect was measured by the inhibition of DNA precursor (thymidine) incorporation. The stability of MMC as a function of pH_e was determined. About 24% of MMC was degraded following 2 hr exposure at pH_e 5 and 2% at pH_e 6 and 7.4. Results. The drug concentrations required to inhibit thymidine incorporation by 50% (IC₅₀) were corrected for the degraded MMC at acidic pH_e. The results showed no pH-dependent MMC activity in human patient bladder tumors nor in RT4 multilayer cultures; the IC₅₀ values were about 10 µg/ml at all three pH_e. In contrast, the monolayer RT4 cultures showed a pH-dependent MMC cytotoxicity; the IC₅₀ were 0.1, 0.8 and 1.2 µg/ ml at pH_e 5,6 and 7.4, respectively (p < 0.05). Pre-incubation of multi-layered RT4 cultures in acidic pH medium for 8 hr enhanced the MMC activity; the IC₅₀ was reduced by about 5 fold at pH_e 5 and about 3 fold at pH_e 6. Similar pH-dependent MMC activity was found when multilayers were pre-treated for 1 hr with 0.5 µml nigericin, a proton ionophore known to cause the intracellular pH (pH_i) to equilibrate with pH_e. Conclusions. These data suggest that the difference in the pH dependency of MMC activity in the monolayer and multilayer systems was due to the different experimental conditions. The time lag for pH_i to equilibrate with pH_e in the multilayer systems and the instability of MMC at low pH_e imply that the efficacy of intravesical MMC therapy is unlikely to be enhanced by using acidic dosing solution.     

Associations between health risk appraisal scores and employee medical claims costs in a manufacturing company

BACKGROUND. The bivariate relationships between 18 health-related measures on a health appraisal and prospective medical claims costs were examined among 1,838 employees for three consecutive years. METHODS. Employees were classified into high- or low-risk categories for each of the 18 health-related measures, and divided into high- or low-cost categories according to their averaged three-year medical costs respective to the mean of their sex/age subgroup. RESULTS. Average annual medical costs for the 18 health-related measures were $67 to $778 higher for the employees classified at high risk. The high-cost category was statistically associated with high-risk status in 11 of 18 health-related measures with a high-cost/high-risk to high-cost/low-risk ratio of 1.26 to 2.50. The average annual medical claims costs were also significantly related to number of high-risk classifications. DISCUSSION. This study provides strong statistical evidence that, regardless of age and sex, employees in this sample with positive behaviors cost less in medical claims from 11 of 18 health-related measures.     

双能量X线骨质密度测量仪监测小儿下肢骨延长骨矿物质的变化

目的　在儿童骨延长的患儿中 ,为了能够有效地控制骨延长的速率 ,达到骨延长的目的 ,采用双能量X线骨质密度测量仪 (dualenergyX Rayabsorptiometry ,DEXA)监测延长断端骨矿含量 (bonemineralcontent,BMC)的变化。方法　 30例患儿中有 5 0处下肢作了骨延长术 ,平均年龄10 .9岁 (5～ 17岁 ) ,引起短肢的病因不同。术后 7～ 10d开始行骨延长 ,每次延长 0 .2 5mm ,每天 4次。牵引延长期间每周扫描一次 ,拆除外固定器后每 2周扫描一次到术后 2年。DEXA扫描的分辨率是 1mm× 1mm ,扫描速度 30mm/s。比较不同延长时期中骨矿含量的变化。分析不同病因和不同外固定器之间骨矿含量变化的差别。结果　不同固定器之间骨矿含量的差别无著性意义。根据骨延长区BMC增加速率 ,将患儿分为快速组、一般组和慢速组。快速组每日BMC增加速率为 0 .3%～ 0 .6 % ,新骨生长快速 ;一般组每日BMC增加 0 .1%～ 0 .3% ,新骨中速生长 ;慢速组每日增加 <0 .1% ,新骨生成缓慢。骨矿化速率与原发病因相关。结论　DEXA能动态监测骨延长中新生骨的骨矿含量的变化 ,根据骨矿含量变化的程度 ,能够调整骨延长的速率 ,从而达到预期骨延长的目的。     

Pentoxifylline inhibits human peritoneal mesothelial cell growth and collagen synthesis: effects on TGF-beta

BACKGROUND: Prevention or treatment of peritoneal fibrosing syndrome has become an important issue in patients on continuous ambulatory peritoneal dialysis (CAPD). Recent evidence has suggested that mesothelial stem cell proliferation and matrix over-production predispose the development of peritoneal fibrosis. We investigated whether pentoxifylline (PTX) affects human peritoneal mesothelial cell (HPMC) growth and collagen synthesis. METHODS: HPMC was cultured from human omentum by an enzymic disaggregation method. Cell proliferation was assayed using a methyltetrazolium uptake method. Cell cycle analysis was performed by flow cytometry. Collagen synthesis was measured by 3H-proline incorporation into pepsin-resistant, salt-precipitated collagen. Prostaglandins and cAMP were determined by enzyme immunoassay. Northern blot analysis was used to determine mRNA expression. RESULTS: Our data show that PTX inhibited serum-stimulated HPMC growth and collagen synthesis in a dose-dependent manner. Cell cycle analysis showed that PTX arrested the HPMCs in the G1 phase. PTX decreased the procollagen alpha1 (I) mRNA expression either stimulated by serum or transforming growth factor-beta (TGF-beta). PTX did not alter prostaglandins synthesis but dose-dependently increased intracellular cAMP level. PTX, the same as 3-isobutyl-l-methylxanthine, could potentiate prostaglandin E1 (PGE1) increased cAMP levels of HPMC. The antimitogenic and antifibrogenic effects of PTX on HPMC were reversed by N-[2]-((p-Bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide (H-89). Therefore, the mechanism of these effects may be due to the phospodiesterase inhibitory property of PTX. CONCLUSIONS: These data suggest that PTX may have a role in treating peritoneal fibrosing syndrome.     

Longitudinal neurological follow-up of a group of HIV-seropositive and HIV-seronegative hemophiliacs: results from the hemophilia growth and development study

BACKGROUND: Boys and young men with hemophilia treated with factor infusions before 1985 had a substantial risk of acquiring the human immunodeficiency virus (HIV) and the acquired immunodeficiency syndrome. This study was designed to assess the effects of HIV and hemophilia per se on neurological function in a large cohort of subjects with hemophilia, and to investigate the relationships between neurological disease and death during follow-up. METHODS: Three hundred thirty-three boys and young men (207 HIV seropositive and 126 HIV seronegative) were evaluated longitudinally in a multicenter, multidisciplinary study. Neurological history and examination were conducted at baseline and annually for 4 years. The relationship between neurological variables, HIV serostatus, CD4+ cell counts, and vital status at the conclusion of the study was examined using logistic regression models. RESULTS: The risks of nonhemophilia-associated muscle atrophy, behavior change, and gait disturbance increased with time in immune compromised HIV-seropositive subjects compared with HIV seronegative or immunologically stable HIV-seropositive subjects. The risk of behavior change in immune compromised HIV-seropositive hemophiliacs, for example, rose to 60% by year 4 versus 10% to 17% for the other study groups. Forty-five subjects (13.5%), all of whom were HIV seropositive, died by year 4. Subjects who died had had increased risks of hyperreflexia, nonhemophilia-associated muscle atrophy, and behavior change. CONCLUSIONS: These results indicate that immune compromised, HIV-seropositive hemophiliacs have high rates of neurological abnormalities over time and that neurological abnormalities were common among subjects who later died. By contrast, immunologically stable HIV-seropositive subjects did not differ from the HIV-seronegative participants. Hemophilia per se was associated with progressive abnormalities of gait, coordination, and motor function.