Vestibular Schwannoma Hypofractionated Stereotactic Radiation Therapy in Five Fractions.

AIM: To retrospectively analyse the long-term results of hypofractionated stereotactic radiation therapy (HSRT) applied in five fractions for vestibular schwannomas. MATERIALS AND METHODS: One hundred and thirty-four patients with vestibular schwannomas underwent medical treatment of HSRT. The median follow-up time interval was 54 months (range 6-121 months). All patients had a prescribed dose of 22 Gy in five fractions to D90. Restaging was carried out by thin-slice contrast-enhanced T1 magnetic resonance imaging. Progression was defined as 2 mm post-treatment tumour enlargement. Progression or death for any reason was counted as an event in progression-free survival rates. Acute toxicity was defined as adverse events occurring within 3 months of HSRT; long-term toxicity was defined as such events occurring after 3 months. RESULTS: In 74/128 patients who had >6 months of follow-up (54%), the HSRT resulted in a partial or a complete response. The mean time interval for response in 50% of these was 4 years, whereas in 49 patients (38%) vestibular schwannomas failed to show any response, resulting in stable disease. Five of 128 patients (4%) showed marked progressive vestibular schwannomas after treatment in the first 3 years; two of them received conventionally fractionated radiation therapy. Local control at 3, 5 and 7 years was 96%, 95% and 94%, respectively. Seven were lost to follow-up. The median planning target volume was 2.1 ml (range 0.78-8.66). The 3- and 5-year progression-free survival rates were 95% and 94%, respectively. Seven patients reported a marked deterioration in hearing ability. Post-radiation therapy magnetic resonance imaging showed variability in oedema collection, but no patient suffered from radio-necrosis. Grade 2 temporary facial nerve disorders were observed in 10 patients (8%) 3-6 months after HSRT. CONCLUSION: Delivering HSRT in five fractions for vestibular schwannoma appears safe and efficient, combining both efficiency and short treatment time while optimising neurological function preservation.

It takes time after bilateral nephrectomy for better control of resistant hypertension in renal transplant patients.

UNLABELLED: Severe resistant hypertension in end-stage renal disease patients has traditionally been an indication for bilateral nephrectomy (BN) before kidney transplantation. Nevertheless the influence of BN on successful control of hypertension has not been well documented. We sought to clarify the effect of BN on blood pressure patterns and control in renal transplant patients. MATERIALS AND METHODS: We retrospectively reviewed 28 patients who underwent BN between November 2003 and May 2009 before or after kidney transplantation. Nineteen of them were under treatment with 4 or 5 antihypertensives according to the international guide lines; they had BN for resistant hypertension. They were considered as group 1 (G1). Nine patients operated for indications other than resistant hypertension; they constitute group 2 (G2) and considered as a control group. All patients received triple immunosuppression according to our local protocol. BN was done either before, simultaneously or after transplantation. Antihypertensives were recorded before and after BN. We evaluated our patients at 3 months, 1 year, and 3 years. Acute rejection episodes and calcinurein nephrotoxicity were reported. RESULTS: In G1, the mean age was 30.2 years (range, 10-62). In G2, the mean age was 33.6 years (range, 11-61). Before BN, G1 patients used antihypertensive drugs (3.6 +/- 1.05 drugs per day; mean +/- SD), which was significantly higher than in G2 patients (2.0 +/- 1.65 drugs per day; P = .02). Three months after BN, G1 patients used 2.6 + 0.9 drugs per day, with gradual reduction in number of antihypertensives to 1.4 +/- 1.3 drugs per day at 3 years (P = .008). In G2, there was reduction in antihypertensive drug number per day, which was insignificant during the follow-up period. No difference was noted between G1 and G2 drug administered after BN. We conclude that BN is effective to help blood pressure control, in resistant hypertension in renal transplant patients, but it starts to show up 3 months after surgery, and continues to work for a year and more.

Outcome of renal allografts with multiple arteries.

BACKGROUND: Renal allograft transplantation with multiple arteries (MRA) was always avoided as much as possible as it is technically demanding and carries a higher MSK for complications. This was a single-center study to explore the graft outcomes of kidney transplantation with MRA. PATIENTS AND METHODS: We retrospectively reviewed the medical records of 35 patients who received kidney grafts with MRA for the surgical technique, surgical complications, graft function, and graft survival. The results were compared with those achieved in recipients of kidney grafts with a single renal artery (SRA). RESULTS: Of 35 grafts, there were 2 renal arteries in 30 grafts, and 3 renal arteries in 5 grafts. In the MRA group, there were 7 instances of surgical complications, the mean serum creatinine levels were 122, 139, and 156 micromol/L at 1 month, 1 year, and 5 years, respectively, and the actuarial graft survival rates were 94.3%, 88.6%, and 83% at 1, 5, and 10 years, respectively. In the SRA group, there were 56 instances of surgical complications, the mean serum creatinine levels were 115, 121, and 141 micromol/L at 1 month, 1 year, and 5 years, respectively, and the actuarial graft survival rates were 93.7%, 88.1%, and 84.4% at 1, 5, and 10 years, respectively. CONCLUSION: Although transplantation of MRA grafts might carry a relatively higher risk for complications, it is justified because it gives results comparable with those achieved in SRA.

Renal allograft venous thrombosis is salvageable.

BACKGROUND: Renal vein thrombosis (RVT) is an uncommon but serious complication. It usually occurs early after surgery. While compression of the renal vein is the most common cause, early rejection and hemostatic defects are other known causes. The symptoms are nonspecific and diagnosis is often delayed. Ultrasonography and renal isotope scan findings may resemble acute rejection or acute tubular necrosis. PATIENTS AND METHODS: We retrospectively reviewed the records of 684 recipients who were transplated between November 1993 and May 2006. The diagnosis of RVT was suspected by an unexplained drop in urine output, rise in serum creatinine, or hematuria, and confirmed by Doppler ultrasound and isotope scanning. Urgent exploration was performed in all suspected cases. RESULTS: Seven incidences of biopsy-proven RVT were encountered, including 3 associated with hematoma and 1 with rejection. Four grafts were from cadaveric donors. Three grafts were salvaged. CONCLUSIONS: The incidence of RVT in the present series was 1%. All cases developed in the first 2 weeks after transplantation. It was more common in adults, in female recipients, and in cadaveric grafts. Early diagnosis and intervention were the keys to salvage.

Single daily dose administration of cyclosporine in renal transplant recipients.

Cyclosporine (CsA) microemulsion has been the mainstay immunosuppressive agent for renal transplant recipients for years. A single daily dosing of cyclosporine (SD) is rarely used. The objective of this study was to evaluate the efficacy of SD versus twice daily dosing of CsA. Retrospective evaluation of SD use was conducted for 44 renal transplant recipients for 12 months (study group). Equal numbers of matched recipients were selected for age, sex, HLA mismatch, donor type, and immunosuppressive regimen (control group). We measured CsA trough (C0) and peak (C2) blood levels, 12-hour CsA profile, and the area under the concentration-time curve (AUC). There were significant differences in C0, C2, and calculated AUC after shifting to SD. In the study group, the mean AUC was 4619 ng/mL/h before versus 6567 ng/mL/h after shifting to SD (P=.004). This became more therapeutic and identical to the mean AUC in the control group, which was 6551 ng/mL/h. Total daily CsA dose was significantly lower in the study group compared with the control group (P<.0001). A significantly higher incidence of hepatitis was observed among the study group (P=.011). There were significantly fewer adverse effects in patients in the study group than the control group. There were no significant differences in graft and patient outcomes between the groups. We concluded that CsA dose should be individualized in renal transplant recipients especially if they have viral hepatitis. SD has the advantage of decreasing dosage and CsA-related adverse effects while maintaining optimal graft function.

Effect of oxidation on the properties of apolipoproteins A-I and A-II.

Purified apolipoprotein A-I has been separated by reversed-phase high performance liquid chromatography (HPLC) into multiple peaks and these peaks have been characterized. One peak, apoA-Ib had a relatively longer retention time on HPLC but its retention time could be shortened by treatment by hydrogen peroxide. CNBr cleavage studies indicated that the differences in apoA-Ib and in its oxidation product, apoA-Ia, were due to the different oxidation states of methionine. This phenomenon was also observed in apoA-II, where methionine oxidation produced two more forms of this apolipoprotein in addition to the native form. These isomers were found to have different secondary structures and affinities for lipid. Model peptide analogs of the amphipathic helix with the same sequence but with methionine and methionine sulfoxide at the nonpolar face of the amphipathic helix were synthesized and studied. It was found that the lipid affinities of these synthetic peptide isomers were very different. They also differed in their secondary structures as studied by circular dichroism (CD). We propose that methionine oxidation introduces hydrophilic residues at the nonpolar face of the amphipathic helical domains of these apolipoproteins and, therefore, alters their secondary structure and lipid affinity.

Inhibition of chondroitin and heparan sulfate biosynthesis in Chinese hamster ovary cell mutants defective in galactosyltransferase I.

We have isolated five Chinese hamster ovary cell mutants defective in galactosyltransferase I (UDP-D-galactose:xylose beta-1,4-D-galactosyltransferase) and studied the effect of p-nitrophenyl-beta-D-xyloside supplementation on glycosaminoglycan biosynthesis in the mutant cells. Assays of galactosyltransferase I showed that the mutants contained less than 2% of the enzyme activity present in wild-type cells, and enzyme activity was additive in mixtures of mutant and wild-type cell extracts, suggesting that the mutations most likely defined the structural gene encoding the enzyme. Cell hybridization studies showed that the mutations in all five strains were recessive and that the mutants belonged to the same complementation group. The mutants contained wild-type levels of xylosyltransferase (UDP-D-xylose:core protein (serine) beta-D-xylosyltransferase), lactose synthase (UDP-D-galactose:N-acetyl-glucosaminide beta-1,4-D-galactosyltransferase), and lactosylceramide synthase (UDP-D-galactose:glucosylceramide beta-1,4-D-galactosyltransferase). Their sensitivity to lectin-mediated cytotoxicity was virtually identical to that of the wild-type, indicating that there were no gross alterations in glycoprotein or glycolipid compositions. Anion-exchange high performance liquid chromatography of 35S-glycosaminoglycans from one of the galactosyltransferase I-deficient mutants showed a dramatic reduction in both heparan sulfate and chondroitin sulfate, demonstrating that galactosyltransferase I is responsible for the formation of both glycosaminoglycans in intact cells. Surprisingly, the addition of 1 mM-p-nitrophenyl-beta-D-xyloside, a substrate for galactosyltransferase I, restored glycosaminoglycan synthesis in mutant cells. This finding suggested that another galactosyltransferase, possibly lactose synthase, can transfer galactose to xylose in intact cells.

Studies of synthetic peptide analogs of the amphipathic helix. Effect of charge distribution, hydrophobicity, and secondary structure on lipid association and lecithin:cholesterol acyltransferase activation.

Four peptides capable of forming an amphipathic alpha-helix have been synthesized and their conformational and lipid-binding properties studied. These peptides have been designed to vary the alpha-helix-forming potential as well as the charge distribution of the model peptide. The resulting peptide analogs and their complexes with dimyristoyl phosphatidylcholine were studied by using right angle light scattering, negative stain electron microscopy, nondenaturing gradient gel electrophoresis, circular dichroism, intrinsic tryptophan fluorescence, and differential scanning calorimetry techniques. The four analogs, [Glu4,9, Leu11,17] (reverse-18A, [Glu4,9, Leu5,11,17] reverse-18A, [Glu1,8, Leu11,17] 18A, and [Glu1,8, Leu5,11,17] 18A were derived from a model amphipathic peptide Asp-Trp-Leu-Lys-Ala-Phe-Tyr-Asp-Lys-Val-Ala-Glu-Lys-Leu-Lys-Glu-Ala-Phe (18A) whose lipid-associating properties strongly mimic apolipoprotein A-I or derived from Lys-Trp-Leu-Asp-Ala-Phe-Tyr-Lys-Asp-Val-Ala-Lys-Glu-Leu-Glu-Lys-Ala-Phe (reverse-18A), a peptide with little affinity for lipid and having a reversed charge distribution compared to the 18A peptide. We have shown that by substituting glutamic acid and leucine for aspartic acid and alanine, respectively, in a weak lipid-associating amphipathic helix peptide, the lipid-associating ability can be increased. Thus, peptides with both kinds of charge distribution can associate with the lipid. The ability of the peptide to disrupt phospholipid bilayers, however, is higher for 18A analogs compared to the reverse-18A analogs even after increasing the helix-forming potential and hydrophobicity. In addition to forming smaller lipoprotein particles, the modified 18A analogs were much superior to the modified reverse-18A analogs in their ability to activate the enzyme lecithin:cholesterol acyltransferase. This demonstrates that the positions of charged residues in the amphipathic helix play an important role in lecithin:cholesterol acyltransferase activation.

Structural and biological studies on synthetic peptide analogues of a low-affinity calcium-binding site of skeletal troponin C.

We have synthesized four oligopeptides that are structural analogues of a low-affinity Ca2+-specific binding site (site II) of rabbit skeletal troponin C. One analogue (peptide 3) was a dodecapeptide with a sequence corresponding to the 12-residue Ca2+-binding loop (residues 63-74 in troponin C), two (peptides 4 and 5) were 23-residue in length, corresponding to residues 52-74 of the protein, and the fourth (peptide 6) was a 25-residue peptide corresponding to residues 50-74. All four peptides had one amino acid substitution within the 12-residue binding loop in which phenylalanine at position 10 was replaced by tyrosine to provide a marker for spectroscopic studies. In addition, peptides 3 and 4 each had a second substitution within the binding loop where glycine at position 6 was replaced by alanine. The second substitution was motivated by the conservation of glycine at the position in the Ca2+-binding loops of all four Ca2+-binding sites in troponin C. The peptides were characterized by their intrinsic fluorescence, ability to enhance the emission of bound Tb3+, affinity for Ca2+ and Tb3+, and circular dichroism. The affinity for Ca2+ was in the range 10-10(2) M-1, and the affinity for Tb3+ was in the range 10(4)-10(5) M-1. The binding constants of the longer peptides were several-fold larger than that of the dodecapeptide. With peptides 4 and 5, substitution of glycine by alanine at position 6 within the 12-residue loop decreased the affinity for Ca2+ by a factor of four, but had little effect on the affinity for Tb3+. However, the mean residue ellipticity of peptide 4 was substantially higher than that of peptide 5. Since peptide 4 differs from peptide 5 only in the substitution of glycine at position 6 in the loop segment, the conservation of glycine at that position may serve a role in providing a suitable secondary structure of the binding sites for interaction with troponin I. Peptides 4 and 6, when present in a large excess, mimic troponin C in regulating fully reconstituted actomyosin ATPase by showing partial calcium sensitivity and activation of the ATPase. Since these peptides are the smallest peptides containing the Ca2+-binding loop of site II, their biological activity suggests that a Ca2+-dependent binding site of troponin C for troponin I could be as short as the segment comprising residues 52-62.