Cyclin-dependent kinase 5 increases perikaryal neurofilament phosphorylation and inhibits neurofilament axonal transport in response to oxidative stress

Cyclin-dependent kinase 5 (cdk5) phosphorylates the high molecular weight neurofilament (NF) protein. Overexpression of cdk5 inhibits NF axonal transport and induces perikaryal accumulation of disordered phospho-NF cables. Experimental and clinical motor neuron disease is characterized by oxidative stress, increased cdk5 activity, and accumulation of phospho-NFs within perikarya or proximal axons. Because oxidative stress increases cdk5 activity in experimental motor neuron disease, we examined whether oxidative stress induced cdk5-mediated NF phosphorylation. Treatment of cultured neuronal cells with hydrogen peroxide inhibited axonal transport of green fluorescent protein-tagged NF subunits and induced perikaryal accumulation of NF phosphoepitopes normally confined to axons. These effects were prevented by treatment with the cdk5 inhibitor roscovitine or transfection with a construct expressing the endogenous cdk5 inhibitor peptide. These findings indicate that oxidative stress can compromise NF dynamics via hyperactivation of cdk5 and suggest that antioxidants may alleviate multiple aspects of neuropathology in motor neuron disease.     

Effects of cadmium(II) on (+/-)-anti-benzo[a]pyrene-7,8-diol-9,10-epoxide-induced DNA damage response in human fibroblasts and DNA repair: a possible mechanism of cadmium's cogenotoxicity

Cadmium, a widespread environmental pollutant and a cigarette smoke constituent, enhances the genotoxicity of benzo[a]pyrene (BP). The mechanism(s) underlying the potentiation of BP-induced genotoxicity by Cd2+ is not clearly understood. Our studies of the effects of noncytotoxic concentrations of Cd2+ on the levels of p53 and p21 in (+/-)-anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE)-treated human fibroblasts showed that Cd2+ decreased BPDE-induced p21 levels in a dose-dependent manner whereas p53 accumulation is attenuated only at higher noncytotoxic concentrations of cadmium. These findings suggest that both the activity and the accumulation of p53 in response of BPDE treatment are inhibited by Cd2+ although the possibility of p53-independent p21 transactivation cannot be ruled out. Exposure of synchronized human fibroblast cells to 0.5 microM of BPDE caused 72% of the cells remaining in G1 phase as compared to 52% in the case of untreated cells. Treatment of the cells with CdCl2 prior to exposing them to BPDE caused a decrease in the G1 population (72 to 54%) in a dose-dependent manner. An in vitro repair assay of BPDE-damaged pUC18 plasmid DNA using untreated and cadmium-treated nucleotide excision repair (NER) proficient HeLa extract showed that cadmium impaired the ability of HeLa cell extract to repair BPDE-damaged pUC18 DNA. Our findings indicate that cadmium not only inhibits NER pathway-dependent repair of BPDE-damaged DNA but also impairs p53 and p21 responses and overrides BPDE-induced G1-S cell cycle arrest. The effect of cadmium on these processes may explain, at least partly, the potentiating effect of the metal on the genotoxicity of BP.     

Effect of oestrogen replacement therapy on serum lipid profile

BACKGROUND: Oestrogen deficiency in postmenopausal women alters the lipid metabolism unfavourably. AIM: To evaluate the effects of oral and transdermal oestrogen replacement therapy (ORT) on serum lipid profile. METHODS: Ninety hysterectomised and oophorectomised women were randomised into three equal groups (no hormones; oral conjugated equine oestrogen, 0.625 mg/day; transdermal oestradiol patches, 50 microg/day). Serum concentrations of total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol and triglycerides were determined at the baseline and after 3 and 6 months of therapy. Student's t-test was used for statistical evaluation. RESULTS: Most of the hysterectomised women had abnormal serum lipid profile, especially HDL cholesterol levels (less than 40 mg/dL in 87%). A significant decline in the levels of serum cholesterol (total) as well as LDL and a significant increase in HDL cholesterol levels were observed following ORT by both modes, the response being comparatively rapid with oral route. After 3 and 6 months, the number of cases with HDL cholesterol levels above 40 mg/dL increased from initial 13 to 63% and 87% (oral) and 30 and 60% (transdermal), respectively. Serum triglyceride levels declined significantly with transdermal therapy but increased with oral ORT. CONCLUSIONS: Oestrogen replacement therapy either via oral or transdermal route has a beneficial effect on serum lipid profile of menopausal women. Whereas the oral route is more effective in increasing HDL cholesterol levels, the transdermal route is better for reducing the serum triglyceride level; hence, the latter should be the route of choice in women with high serum triglyceride levels.     

Pelviureteric junction obstruction: how much is the extent of the upper ureter with defective innervation needing resection?

Background/Purpose: It is well realized that Anderson-Hyne’s pyeloplasty fails to improve the drainage pattern and renal functional parameters in a few cases of hydronephrosis because of pelviureteric junction (PUJ) obstruction. The purpose of this study is to delineate the lower extent of the abnormally innervated pelviureteric junction by S-100 immunohistochemistry, which requires surgical removal.Methods: Thirty pelviureteric junction (PUJ) specimens were analyzed by histology and by S-100 immunohistochemistry after serial sectioning of the resected ureter and compared with the variables age, calyceal separation, parenchymal thickness, differential renal function, glomerular filtration rate (GFR), and the measured constricted ureteral segment on gross examination.Results: No significant correlation was noted (P > .05) when the histology was analyzed to find any association with any of the variables studied. The length of the visible constricted segment ranged from 2 mm to 15 mm (mean, 5.37 mm). The abnormally innervated segment was much longer than the length of the visible constricted segment in 24 and of the same length in 5 specimens. However, in 1 case, the abnormal innervation segment was shorter than the macroscopic constriction by 3 mm. The maximum difference in length between the visible constriction and the lower limit of defective innervation was 8 mm.Conclusions: The abnormally innervated ureteral segment below the PUJ in hydronephrosis is longer than the visible constricted segment at the time of surgery, and the ureter should be excised at least 8 mm or more beyond the visible lower limit of the constricted segment in cases of Anderson-Hyne’s pyeloplasty.     

The value of laparoscopic staging for patients with colorectal metastases

BACKGROUND: Resection offers the only chance of cure for hepatic colorectal metastases. However, preoperative staging does not always reliably detect unresectable disease. The aim of this study was to investigate the role that laparoscopy with ultrasound may have in detecting unresectable disease, thus sparing patients from unnecessary laparotomy with the associated morbidity and cost. METHODS: A retrospective review of all patients considered for liver resection of colorectal metastases during a 3-year period was performed, analyzing factors likely to predict resectable disease, rates of resectability, and success of laparoscopic staging at detecting unresectable disease. RESULTS: Of 73 patients with resectable disease on computed tomography, 24 were deemed to need laparoscopy, and 49 proceeded directly to laparotomy. Those first undergoing laparoscopy had shorter disease-free intervals between diagnosis of colorectal cancer and detection of hepatic recurrence and greater numbers of hepatic metastases. Twelve of the 24 patients who underwent laparoscopy had unresectable disease, and 8 of these were detected at laparoscopy. Forty-six of the 49 patients proceeding to laparotomy directly had resectable disease. CONCLUSIONS: Laparoscopic staging of hepatic colorectal metastatic disease detects most unresectable disease, preventing unnecessary laparotomy. The likelihood of disease being unresectable is in part predicted by the disease-free interval and the number of hepatic metastases.     

Frequency of gastrointestinal involvement and its clinical significance in mantle cell lymphoma

BACKGROUND: The reported frequency of gastrointestinal (GI) tract involvement in patients with mantle cell lymphoma (MCL) is 15-30%. However, this figure most likely is an underestimate because most patients with MCL involving the GI tract previously reported were examined endoscopically only if they had GI tract symptoms. The impact of endoscopic assessment on the management of MCL patients is unknown. METHODS: From March 1998 to May 2001 baseline upper and lower endoscopy of the GI tract was performed in consecutive untreated patients with MCL as part of a prospective therapeutic trial. Biopsies were performed on abnormal as well as macroscopically normal mucosa. Endoscopy was repeated during treatment and as part of follow-up evaluations. RESULTS: Only 26% of patients presented with GI symptoms at the time of diagnosis. MCL was present histologically in the lower GI tract of 53 of 60 patient (88%) and in the upper GI tract of 28 of 58 patients (43%). Microscopic evidence of MCL was found in 84% of patients with normal visual (macroscopic) findings by lower endoscopy and in 45% of patients with macroscopically normal findings by upper endoscopy. Despite this high frequency of GI tract involvement, the use of upper and lower endoscopy with biopsies in this group of patients resulted in changes in clinical management in only three (4%) patients. CONCLUSIONS: Gastrointestinal tract involvement was found to be present in most patients with MCL, usually at a microscopic level involving macroscopically normal mucosa. The use of aggressive staging evaluation of the GI tract was found to have little impact on patient management decisions in the current study.     

Cyclophosphamide treatment modifies tumor oxygenation and glycolytic rates of RIF-1 tumors: 13C magnetic resonance spectroscopy, Eppendorf electrode, and redox scanning

The effect of cyclophosphamide (Cp) on the glycolytic rate of radiation-induced fibrosarcomas (RIF-1) was measured in vivo in C3H mice by following the production of [3-(13)C]lactate after tail vein infusion of labeled [1-(13)C]glucose. Cp administered i.p. at a dose of 300 mg/kg caused a significant drop in glycolytic rate 24 h after treatment (P < 0.01). This drop was accompanied by an increase in [C-3]/[C-4] glutamate ratio in perchloric acid extracts of the tumors, indicating an increase in the Kreb's cycle activity. Treatment with Cp led to a significant decrease (P < 0.01) in tissue pO(2), measured in vivo with an oxygen Eppendorf electrode. Increases in NADH levels were also observed in rapidly frozen excised tumors examined by three-dimensional optical redox scanning. A significant decrease in tumor pO(2) and an increase in the NADH levels are suggestive of an increase in oxygen consumption by these tumors after Cp treatment. Overall, these data indicate that the reduction in glycolytic rate of Cp-treated RIF-1 tumors is due to an increase in aerobic metabolism.