Mokenge P. Malafa

Dose-Dependent Protection by Lipoic Acid against Cisplatin-Induced Nephrotoxicity in Rats: Antioxidant Defense System

This study was designed to investigate the role of graded doses of lipoic acid pretreatment against cisplatin-induced nephrotoxicity. Male Wistar rats were divided into six groups and treated as follows: 1) vehicle (saline) control; 2) cisplatin (16 mg/kg, intraperitoneally); 3) lipoic acid (100 mg/kg, intraperitoneally); 4) cisplatin plus lipoic acid (25 mg/kg); 5) cisplatin plus lipoic acid (50 mg/kg) and 6) cisplatin plus lipoic acid (100 mg/kg). Rats were sacrificed three days after treatment, and plasma as well as kidneys were isolated and analyzed. Plasma creatinine increased (677% of control) following cisplatin administration alone which was decreased by lipoic acid in a dose-dependent manner. Cisplatin-treated rats showed a depletion of renal glutathione (GSH), increased oxidized GSH and decreased GSH/GSH oxidized ratio (62%, 166% and 62% of control), respectively which were restored with lipoic acid pretreatment. Renal superoxide dismutase, catalase, glutathione peroxidase (GSH peroxidase) and glutathione reductase activities decreased (62%, 75%, 62% and 80% of control), respectively, and malondialdehyde content increased (204% of control) following cisplatin administration, which were restored with increasing doses of lipoic acid. The renal platinum concentration increased following cisplatin administration, which was possibly decreased by chelation with lipoic acid. The data suggest that the graded doses of lipoic acid effectively prevented a decrease in renal antioxidant defense system and prevented an increase in lipid peroxidation, platinum content and plasma creatinine concentrations in a dose-dependent manner.

Inhibition of angiogenesis and promotion of melanoma dormancy by vitamin E succinate

BackgroundRelapse of melanoma after surgical treatment remains a significant clinical problem in need of novel therapies. Vitamin E succinate (VES) is a promising antitumor micronutrient. We evaluated the effect of VES on melanoma dormancy and angiogenesis.MethodsB16F10 melanoma cells were allografted in mice. The effect of VES on melanoma dormancy was measured by monitoring tumor volume. Tumor vascularity was quantitated with CD31 immunostaining. The expression of vascular endothelial growth factor (VEGF), VEGF receptor 1, and VEGF receptor 2 in tumors was assessed by the intensity of immunostaining. VES effect on secreted VEGF protein and VEGF promoter activity was measured with enzyme-linked immunosorbent assay and transient transfection assay, respectively. Significance was determined by analysis of variance.ResultsVES promoted melanoma dormancy (P=.0019) and inhibited melanoma angiogenesis (P<.0001). VES also significantly suppressed the expression of VEGF, VEGF receptor 1, and VEGF receptor 2 in melanoma tumors (P<.0001). Melanoma VEGF secretion (P=.0077) and melanoma VEGF promoter activity (P<.05) were significantly inhibited by VES.ConclusionVES promotes melanoma dormancy and inhibits melanoma angiogenesis. The mechanism of the VES antiangiogenesis effect involves the inhibition of VEGF gene transcription. These findings support future studies of VES in the prevention of melanoma metastasis.

Complications of hepatic artery infusion: a review of 4580 reported cases.

Purpose: The resurgence of hepatic artery infusion (HAI) for the treatment of colorectal liver metastases has been dampened by concern over its complications. We have reviewed the incidence and frequency of complications associated with HAI and discussed the factors associated with these complications.Methods: A PUBMED search was conducted from 1950–2001 using various combinations of these keywords: hepatic arterial infusion, colorectal carcinoma, complications, and trials. The main inclusion criterion was the reporting of HAI complications. The main exclusion criterion was duplicated patients. Extracted data included chemotherapeutic agents, catheter technique, drug toxicities, and catheter related complications. Relative risks and 95% confidence intervals were calculated.Results: We reviewed 437 articles/abstracts and included 101 studies. 4580 patients with 4582 toxicities and complications were reported. The mortality rate was 1%. The most common toxicities were: GI symptoms 22%, chemical hepatitis 19%, and bone marrow toxicity 8%. 5-fluorouracil (5-FU) HAI had statistically significant risk for GI symptoms and bone marrow toxicity. Floxuridine (FUDR) HAI had statistically significant risk for chemical hepatitis, sclerosing cholangitis, and biliary toxicity. The most common catheter complications were: hepatic artery occlusion 6%, catheter thrombosis 5%, and catheter displacement 7%.Conclusions: This literature review of the complications of HAI confirms a low mortality associated with HAI. Sclerosing cholangitis and chemical hepatitis are associated with the use of FUDR, while the use of 5-FU is associated with bone marrow toxicity. Our observations support the development of hepatic cytoprotective agents and other effective anti-tumor agents to improve the results and morbidity of HAI for colorectal liver metastases.

Angiogenesis Correlates With Metastasis in Melanoma

Background: Angiogenesis has been correlated with melanoma progression, but its role in melanoma metastasis is unclear.Methods: To determine whether angiogenesis correlates with the presence of melanoma metastases, we compared the number of microvessels in the primary melanomas of 12 patients presenting with metastases to those of 13 patients without metastases. Patient groups were matched for gender, age, tumor depth, and histological type and anatomical location of the primary melanoma. Microvessels were stained with factor VIII antibody and counted.Results: Microvessel counts were significantly greater for the metastatic than the nonmetastatic melanomas (51.63 ± 14.95 vs. 24.86 ± 8.415; P < .0001). One hundred percent of the metastatic melanomas had a mean microvessel count of ≥ 37, whereas only 8% of the nonmetastatic melanomas had a mean microvessel count of ≥ 37 (sensitivity = 1.00, specificity = .92). Interestingly, patients with lymph node metastases had significantly lower microvessel counts than did patients with distant metastases (42.00 ± .482 vs. 58.50 ± 16.40; P < .05), and significantly higher microvessel counts than did patients without metastases (42.00 ± 3.482 vs. 24.86 ± 8.415; P < .001).Conclusions: An increased number of microvessels in the primary tumors of patients with melanoma correlates with the simultaneous presence of metastases. This suggests that angiogenesis may be important in the process of melanoma metastasis.

Periareolar injection for localization of sentinel nodes in breast cancer patients.

Abstract: u2002 The goal of this study was to evaluate the periareolar injection of technetium 99m sulfur colloid to identify axillary sentinel nodes and compare the number of sentinel lymph nodes identified with preoperative lymphoscintigraphy to intraoperative biopsy using a handheld gamma probe. A total of 104 consecutive patients diagnosed with invasive breast cancer participated in this prospective study, with 81 patients receiving an intradermal periareolar injection and 23 patients receiving an intradermal peritumoral injection of filtered technetium 99m sulfur colloid. Preoperative lymphoscintigraphy was performed for sentinel node mapping and localization. In addition to selective sentinel node biopsy, axillary dissection was performed on all patients to determine false‐negative rates. Routine histologic staining was performed on all identified nodes, along with immunohistochemical staining of sentinel nodes negative on initial routine staining. With an intradermal periareolar injection, the sentinel node identification rate was 91.4% (74/81), axillary metastatic rate 35.1% (26/74), sentinel node positive only 61.5% (16/26), and false negative 3.8% (1/26). With an intradermal peritumoral injection, the sentinel node identification rate was 91.3% (21/23), axillary metastatic rate 42.9% (9/21), sentinel node positive only 88.9% (8/9), and false negative 0% (0/9). A total of 241 sentinel nodes were identified with biplanar lymphoscintigraphy and 173 sentinel nodes were harvested during surgery, yielding a 28.2% increase in sentinel nodes identified with lymphoscintigraphy. This study demonstrates that intradermal periareolar injection of filtered technetium 99m sulfur colloid is successful in identifying axillary sentinel nodes with a low false‐negative rate. Preoperative lymphoscintigraphy aids in the identification and surgical planning of sentinel node biopsy and provides an objective measure of surgical performance.u2002

Effect of cisplatin on the expression of glutathione-S-transferase in the cochlea of the rat

Abstract Glutathione-S-transferase (GST) has been found to conjugate glutathione (GSH) to diverse electrophiles and play a major role in the detoxification of alkylating and platinating agents. However, there is little information regarding the pattern of GST expression in the cochlea. Although cisplatin is ototoxic, its effect on GST in the cochlea is unknown. In the present study we investigated the pattern of GST expression in control and cisplatin-treated cochleas by using the laboratory rat as animal model. Sixteen mature rats were randomly assigned to control or cisplatin groups. After treatment, cochleas were procured and tissues stained by immunohistochemical methods to detect the presence of GST. Optical density measurements were determined to gauge intensity of GST immunostaining. Strong positive GST immunostaining was demonstrated in all cochleas, with the most intense staining found in the spiral ligament and the least in Reissner’s membrane. Mean optic density scores were lower for cisplatin-treated cochleas than for control cochleas in all areas analyzed. These findings showed that GST is expressed throughout the rat cochlea, with cisplatin treatment causing its decreased expression.

Angiogenesis in primary tumor cells of metastatic and nonmetastatic malignant melanoma.

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