Suture patterns and corneal graft rotation in the cadaver eye

Torque and antitorque running sutures as described by Eisner are commonly used in penetrating keratoplasty. We tested the rotational effect of three different 16-bite running suture patterns on eight cadaver eyes, with the following results: (1) the torque pattern rotates the corneal graft counterclockwise by 0.7 +/- 0.1 mm at the wound or 11 degrees; (2) the antitorque pattern rotates the corneal graft clockwise by 0.7 +/- 0.1 mm at the wound or 11 degrees; (3) an intermediate "no torque" pattern, the bites of which form an isosceles triangle, produces no rotational effect. We recommend the use of a "no torque" pattern to minimize corneal graft rotation.     

pH-dependent secondary conformation of the peptide hormone leptin in different buffer solutions

The secondary structure of leptin in each different pH buffer solution (pH 5.35, 6.75, 7.58 and 8.45) was first determined by attenuated total reflection (ATR)/Fourier transform infrared (FT-IR) spectrometer with second-derivative, Fourier self-deconvolution and band curve-fitting methods to quantitatively estimate the secondary structure of leptin. The results indicate that pH induced more stretching vibration of CH2 and bending vibration of C-H and/or symmetric stretching of carboxylate of leptin structure in higher pH buffer solution than in lower pH buffer solution. Moreover, the band area of amide I for leptin in the higher pH buffer solution markedly enlarged, suggesting the amide I contour of leptin was very sensitive to pH to alter the secondary conformation of leptin structure. The structural component and composition of amide I band for leptin in both pH 6.75 and pH 7.58 buffer solutions were similar and had 50-52% helical structure including alpha-helix at 1654 cm-1 and 3(10)-helical structure at 1659-1667 cm-1 and 1640 cm-1. Although the secondary structure of leptin in pH 5.35 and 8.45 buffer solutions were also similar, a different structural information was obtained.     

Influence of α-tocopherol over the time course of experimental IgA nephropathy

 The present study investigated the pathogenesis and the time course of kidney injury in experimental IgA nephropathy. In order to determine an appropriate period in the course of experimental IgA nephropathy to study renal injury and repair, we examined proteinuria and IgA deposition in the renal mesangium after 4, 8, and 16 weeks of mucosal challenge by bovine gamma globulins (BGG) provided in the drinking water. The hallmark of IgA deposition in the mesangium was present after 4 weeks and 8 weeks of BGG inoculation, but by 16 weeks, the mesangial IgA deposition had resolved. In addition, we confirmed our previous report on the beneficial effects of α-tocopherol in reducing proteinuria in IgA nephropathy at 8 weeks, and extended this observation to investigate the effects of dietary supplementation of α-tocopherol at both 4 weeks and 16 weeks. Proteinuria resolved spontaneously at 16 weeks. There is oxidative stress, as suggested by the elevation in plasma and renal malondialdehyde content, and increased fibrogenic cytokine message, as suggested by elevated transforming growth factor β1 mRNA. These increases were clearly blunted by α-tocopherol at both 4 weeks and 8 weeks. Treatment with α-tocopherol was associated with a significant reduction in the severity of proteinuria. Thus, our data suggest that the period between 4 and 8 weeks of BGG vaccination could be relevant in designing an appropriate model to study the molecular biology of the pathogenesis of renal injury and the effects of treatment. The 16-week model may be useful in exploring gene expression involved with spontaneous resolution. Received: 17 February 1998 / Revised: 2 June 1998 / Accepted: 3 June 1998     

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.     

Lamivudine for the prevention of hepatitis B virus reactivation in hepatitis B s-antigen seropositive cancer patients undergoing cytotoxic chemotherapy.

PURPOSE: For cancer patients receiving cytotoxic chemotherapy, hepatitis B virus (HBV) reactivation is a well described complication resulting in varying degrees of liver damage. The objectives of this study were to assess the efficacy of the antiviral agent lamivudine in reducing the incidence of HBV reactivation and diminishing morbidity and mortality of cancer patients with chronic HBV infection during chemotherapy. PATIENTS AND METHODS: Two groups were compared in this nonrandomized study. The prophylactic lamivudine group consisted of 65 patients in a phase II study who were treated with lamivudine before and until 8 weeks after discontinuing chemotherapy. The historical controls consisted of 193 consecutive patients who underwent chemotherapy without prophylactic lamivudine. Significant prognosticators for the development of HBV reactivation were determined based on data from the controls. Potential confounding factors were identified between the two groups. The outcomes were compared. RESULTS: In the controls, lymphoma and anthracycline usage were factors identified to be associated with reactivation. The two groups were comparable in most baseline characteristics, although in the prophylactic lamivudine group, there were significantly more patients with lymphoma and receiving anthracyclines. In the prophylactic lamivudine group, there was significantly less HBV reactivation (4.6% v 24.4% in the controls; P <.001), fewer incidences of hepatitis (17.5% v 44.6%; P <.0001) that were less severe (4.8% v 18.7%; P =.0005), and less disruption of chemotherapy (15.4% v 34.6%; P =.0029). The reduction in overall mortality was not statistically different. CONCLUSION: Prophylactic lamivudine significantly reduced the incidence of HBV reactivation and the overall morbidity of cancer patients undergoing chemotherapy.     

Phase II study of neoadjuvant carboplatin and paclitaxel followed by radiotherapy and concurrent cisplatin in patients with locoregionally advanced nasopharyngeal carcinoma: therapeutic monitoring with plasma Epstein-Barr virus DNA.

PURPOSE: To assess the efficacy of neoadjuvant paclitaxel and carboplatin (TC) followed by concurrent cisplatin and radiotherapy (RT) in patients with locoregionally advanced nasopharyngeal carcinoma (NPC) and to monitor treatment response with plasma Epstein-Barr virus (EBV) DNA. PATIENTS AND METHODS: Thirty-one patients with International Union Against Cancer stages III and IV undifferentiated NPC had two cycles of paclitaxel (70 mg/m2 on days 1, 8, and 15) and carboplatin (area under the curve 6 mg/mL/min on day 1) on a 3-weekly cycle, followed by 6 to 8 weeks of cisplatin (40 mg/m2 weekly) and RT at 66 Gy in 2-Gy fractions. Plasma EBV DNA was measured serially using the real-time quantitative polymerase chain reaction method. Results All patients completed planned treatment. Response to neoadjuvant TC was as follows: 12 patients (39%) achieved partial response (PR) and 18 achieved (58%) complete response (CR) in regional nodes; five patients (16%) achieved PR and no patients achieved CR in nasopharynx. At 6 weeks after RT, one patient (3%) achieved PR and 30 patients (97%) achieved CR in regional nodes, and 31 patients (100%) achieved CR in nasopharynx; 29 patients (93%) had EBV DNA level of less than 500 copies/mL. Neoadjuvant TC was well tolerated, and the most common acute toxicity of cisplatin plus RT was grade 3 mucositis (55%). At median follow-up of 33.7 months (range, 7 to 39.3 months), six distant and three locoregional failures occurred. Plasma EBV DNA level increased significantly in eight of nine patients who experienced treatment failure but did not increase in those who did not. The 2-year overall and progression-free survival rates were 91.8% and 78.5%, respectively. CONCLUSION This strategy was feasible and resulted in excellent local tumor control. Serial plasma EBV DNA provides a noninvasive method of monitoring response in NPC.     

Bladder tissue pharmacokinetics of intravesical taxol

Our previous studies have suggested that the ineffectiveness of intravesical mitomycin C or doxorubicin therapy against muscle-invading bladder cancer is in part because of the inability of these drugs to penetrate the urothelium (the urothelial drug concentration is <5% of the concentration in urine). The goal of the present study was to identify agents that are efficiently absorbed across the urothelium. To evaluate the potential use of taxol in intravesical therapy for bladder cancer, we examined the bladder tissue and systemic plasma pharmacokinetics of intravesical taxol in dogs. Animals (∼8 kg body weight) were given an instillation of taxol at 500 μg in 20 ml water. At 120 min postinstillation, the bladder was emptied and excised, and about 85% of the dose was recovered in the urine. The taxol concentration in the urothelium was about 50% of the concentration in the urine, the concentrations then declined logarithmically in the underlying capillary-perfused tissues. The average tissue concentration (∼2 μg/g) was two to three times the reported plasma concentration of 0.75 μg/ml in patients following intravenous infusion of the >100-fold higher dose of 250 mg/m². The steady-state plasma concentration was <0.02% of the average tissue concentration, and was <0.05% of the maximally tolerated plasma concentration in patients. The octanol:water partitioning coefficients of taxol, doxorubicin, and mitomycin were >99, 0.52, and 0.41, which parallels the rank order of the partitioning across urothelium, i.e. taxol (∼50%) >> doxorubicin ≈ mitomycin C (∼3%). In summary, the partitioning of taxol across the urothelium was more favorable than the partitioning of mitomycin C and doxorubicin, and the systemic concentration of taxol resulting from intravesical treatment was insignificant in spite of the extensive absorption into the bladder. We conclude that intravesical delivery of taxol provides a significant bladder tissue targeting advantage, and that taxol represents a viable candidate drug for intravesical bladder cancer therapy. Received: 20 September 1996 / Accepted: 2 December 1996     

Allogeneic bone marrow transplantation for adult acute lymphoblastic leukemia: a single-centre experience.

Between 1990 and 1997, we performed 29 allogeneic BMTs for acute lymphoblastic leukemia (ALL) patients with HLA-identical sibs. Their median age was 31 years (range 15 to 43); there were 15 males and 14 females. The conditioning protocol was Cy-TBI (n = 15), VP16-Cy-TBI(n = 12), CBV (n = 1) and Bu-Cy (n = 1). Cyclosporin and methotrexate were used for GVHD prophylaxis. The median disease-free survival (DFS) was 12 months (range 1 to 92) with an actuarial 4-years DFS of 42.3 per cent. Three patients died of transplant-related complications before 100 days. Relapse occurred in 11 cases at a median time of 5 months (range 3 to 14). All nine patients relapsing within one year died form resistant leukemia. Three patients died of late treatment-related complications. There were 13 survivors (median follow-up 38 months, range 12-98), with 12 in remission. Only four had limited cGVHD, and all had 100 per cent performance scores. One patient also cleared her chronic hepatitis B carrier status due to acquired immunity. The DFS rates amongst CR1 cases and R1/CR2 cases were comparable (p = 0.39). No long-term DFS is obtained from patients with resistant disease (n = 4). The survival results for BMT at CR1 were superior to those using intensive chemotherapy consolidation (p = 0.29), mainly due to poor late results in the chemotherapy arm. For young ALL patients with HLA-matched siblings, the option of BMT should be considered in light of local consolidation survival results.     

Phase II study of Temodal in the treatment of patients with advanced nasopharyngeal carcinoma

Purpose: A single-institution phase II trial of Temodal (temozolomide, SCH52365) in Chinese patients with advance nasopharyngeal carcinoma was undertaken to determine the efficacy and safety of the drug in this population. Methods: A total of 14 patients with metastatic or locoregionally recurrent nasopharyngeal carcinoma were entered into the study. One patient was unevaluable. Temodal was given at doses of 150 or 200 mg/m² daily on days 1–5 every 28 days. Results: In all, 30 cycles of Temodal were given with no significant toxicity. All 13 (100%) evaluable patients had progressive disease after 2 (84.6%) or 4 (15.4%) courses. Conclusion: Temodal given on this schedule has no activity in advanced nasopharyngeal carcinoma. Received: 9 January 1998 / Accepted: 4 February 1998