Spectroscopic and functional characterization of Lampyris turkestanicus luciferase: a comparative study.

Functional expression and spectroscopic analysis of luciferases from Lampyris turkestanicus and Photinus pyralis were carried out. cDNA encoding L. turkestanicus luciferase was isolated by reverse transcription-polymerase chain reaction, cloned, and functionally expressed in Escherichia coli. The luciferases were purified to homogeneity using Ni-nitrilotriacetic acid Sepharose, and kinetic properties of luciferase from L. turkestanicus were compared with that from P. pyralis. Amino acid differences in its primary structures in relation to P. pyralis luciferase brought about changes in the kinetic properties of the enzyme as evidenced by substantial lowering of Km for ATP, increased light decay time, and decreased thermostability. Luciferase from L. turkestanicus was used to carry out Michaelis-Menten kinetics with a Km of 95.5 muM for ATP and 20 muM for luciferin. Maximum activity was recorded at pH 8.5, so it might be a suitable reporter for microbial screening at alkaline pH. Tryptophan fluorescence for P. pyralis luciferase was higher than L. turkestanicus luciferase. Substitution of some residues in L. turkestanicus luciferase appears to change the kinetic properties by inducing a substantial tertiary structural change, without a large effect on secondary structural elements, as revealed by intrinsic and extrinsic fluorescence, Fourier transform infrared spectroscopy, and near-ultraviolet circular dichroism spectra.

Does donor nephron mass have any impact on graft survival?

OBJECTIVES: Functioning nephron mass namely, the number of nephrons in the grafted kidney, is one of the nonimmunologic factors that may have some impact on long-term graft survival. The aim of this study was to assess the impact of donor nephron mass on graft outcome in the recipient. MATERIALS AND METHODS: From 1989 to 2005, 1000 renal transplants were performed at our center. The 217 studied cases were followed for an average of 8 years. All patients received grafts from living donors. The weight of the grafted kidney (donor nephron mass) as well as the recipient's body mass index (BMI) were measured at the time of operation. Nephron mass index (NMI) was defined as the ratio of donor nephron mass to recipient BMI. Associations between variables were tested by logistic regression and Pearson correlation using the SAS system and S-plus statistical software. To evaluate graft function, we determined serum creatinine values, acute rejection episodes and chronic nephropathy. RESULTS: Mean NMI was 8.07 +/- 0.2 and mean creatinine level was 1.43 +/- 0.4 mg/dL. There were 32 cases (14.7%) of acute rejection, who were managed successfully with antithymocyte globulin (ATG) in 28 cases. Four patients lost their grafts. There were 15 cases (7%) of graft loss due to chronic rejection. Using Pearson correlation, we observed no association between NMI and mean serum creatinine level. Logistic regression showed a significant relation between NMI and acute rejection (P<.05) with an odds ratio of 2.0. There was no significant correlation between NMI and chronic rejection. CONCLUSIONS: The lower the NMI, the greater the short-term graft loss. However, in the long term, no significant correlation was found between graft survival and NMI. Also, mean creatinine level was not significantly different among patients regardless of NMI.

Microchimerism and renal transplantation: doubt still persists.

OBJECTIVE: We sought to study microchimerism in a group of kidney transplant recipients. MATERIALS AND METHODS: In this study, the peripheral blood microchimerism (PBM) after renal transplantation was retrospectively evaluated in 32 male-to-female recipients of living unrelated or cadaveric donor renal transplants. Using a nested polymerase chain reaction (PCR) amplification specific for SRY region of the Y chromosome, microchimerism was detected with a sensitivity of 1:1,000,000. Recipients were compared according to the presence of PBM, acute and chronic rejection episodes, type of allotransplant, recipient and donor age at transplantation, previous male labor or blood transfusion, allograft function (serum creatinine level), and body mass index. RESULTS: Among 32 recipients, 7 (21.9%) were positive for PBM upon multiple testing at various posttransplant times. All microchimeric recipients had received kidneys from living unrelated donors. No significant difference was observed with regard to other parameters. In addition the acute rejection rate in the microchimeric group was 3 (42%) versus 4 (16%) in the nonmicrochimeric recipients (not significant). CONCLUSION: Our results suggested better establishment of microchimerism after living donor kidney transplantation. However, doubt persists concerning the true effect of microchimerism after renal transplantation. It seems that microchimerism alone has no major protective role upon renal allograft survival.

Does renal transplantation improve erectile dysfunction in hemodialysed patients? What is the role of associated factors?

OBJECTIVE: To assess the effect of successful renal transplantation on improvement of erectile function in hemodialysis (HD) patients and the relationship between the degree of patient response and other factors. MATERIALS AND METHODS: From September 2002 to November 2005, erectile function of 64 patients on HD for at least 6 months was evaluated pretransplantation and 6 months posttransplantation by International Index of Erectile Function, version 5 (IIEF-5). Sixty four age-matched persons without renal impairment were enrolled as control group to compare erectile dysfunction (ED) prevalence with the HD group. We evaluated duration of HD, age, and site of arterial anastomosis. In an attempt to find predictors of improvement of ED, after kidney transplantation, we performed linear regression analysis with a backward method. RESULTS: The prevalence of ED in HD patients was 87.5%. Although there were some differences in the prevalence of ED between patients older versus younger than 50 years, the difference was not statistically significant. There was no relationship between the duration of dialysis and the severity of ED in HD group. Compared to the pretransplant IIEF-5 score (13.59), there was significant improvement (19.16). In an attempt to find predictors of ED improvement, we used a linear regression analysis with backward method. Pretransplant IIEF-5 score, age at the time of transplant, and anastomosis to the common iliac artery showed significant associations with improvement, but the duration of dialysis and anastomosis to internal iliac or external iliac artery did not. CONCLUSION: The incidence of ED among hemodialyzed patients is high. Kidney transplantation is the key treatment for this complaint. ED has a major negative impact on the quality of life and family relations. Its treatment is associated with improvement of psychogenic factors. ED is a sensitive topic and many patients will not spontaneously discuss it with their physician, so better to include potency evaluation in posttransplantation list evaluations.

Pelvic nerve neuropathy after kidney transplantation.

OBJECTIVES: We examined the relation of various age, gender, diabetes, hypertension, and graft function with the prevalence of femoral and lateral cutaneous nerves sensory and/or motor disturbances after kidney transplantation. MATERIALS AND METHODS: Among 129 patients who underwent kidney transplantation from April 2001 to March 2002. We excluded, 10 due to preoperative sensory disturbances. We evaluated the prevalence of sensory and/or motor disturbances preoperatively by physical examination and postoperatively by both physical and electromyography examinations. The clinical findings were correlated with the following risk factors: age, gender, preoperative dialysis duration, background diseases. (e.g., diabetes, hypertension), graft weight, nephron mass index, operative and retraction time, and rejection episodes. RESULTS: At 1 to 9 days postoperatively, 31 ng (26%) patients, suffered neuropathy of the lateral cutaneous nerve and 4 (3.3%), femoral neuropathy. No meaningful relation was detected between the incidence of neuropathy and these risk factors. The probability of neuropathy was greater among diabetics, hypertensives, women, and those with graft rejection episodes. All of these complaints were temporary. CONCLUSIONS: Post-kidney transplant femoral and/or lateral cutaneous nerve neuropathy is a prevalent complication particularly in diabetic, hypertensive, and female patients. Neuropathy is also more evident after graft rejection.