Expression of fascin in oral and oropharyngeal squamous cell carcinomas has prognostic significance - a tissue microarray study of 129 cases

AIMS

To elucidate the role of fascin in oral and oropharyngeal squamous cell carcinoma (OSCC) by correlation with clinical parameters.

METHODS AND RESULTS

Paraffin sections using tissue microarrays of 129 patients with OSCC were investigated immunohistochemically. Fascin protein was overexpressed in OSCC cells compared with their non-neoplastic epithelial counterparts. For evaluating the intensity of fascin, 39 (30.2%) were classified as weakly immunoreactive, 76 (58.9%) as moderate reactive and 14 (10.9%) as intensely reactive. For evaluating the distribution of fascin, 64 (49.6%) were classified as < 55% and 65 (50.4%) were classified as >/= 55%. Fascin protein expression was correlated with size or extent of the tumour (P < 0.001), positive lymph node metastasis (P < 0.001), distant metastasis (P = 0.014) and clinical staging (P < 0.001). The immunoreactivity scores of fascin in OSCC were variable but showed significant correlation with histological grade, clinical TNM system and stage.

CONCLUSION

Expression of fascin protein may play an important role in progression of OSCC. Overexpression of fascin contributes to a more aggressive clinical course and suggests the potential of fascin as a new molecular target for therapeutic intervention.

Lovastatin improves histological and functional outcomes and reduces inflammation after experimental traumatic brain injury

Traumatic brain injury (TBI) triggers a complex sequence of inflammatory responses that contribute to secondary injury. Statins have demonstrated neuroprotective effects against brain injury, but the underlying mechanisms remain unclear. This study evaluated the effects of lovastatin on a rat model of controlled cortical impact (CCI) injury. Our two hypotheses were that pre-administration of lovastatin would reduce functional deficits and extent of anatomical brain damage and that lovastatin would attenuate levels of pro-inflammatory cytokines. Rats were injected with lovastatin (4 mg/kg) or vehicle for 5 days and subjected to CCI. Neurological status was evaluated using rotarod and adhesive removal tests. Contusion volume and neuronal degeneration were examined using cresyl violet and FluoroJade B (FJB) histochemistry. Levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) mRNA and protein were assessed by real-time quantitative reverse transcriptase polymerase chain reaction, enzyme-linked immunosorbent assay, and immunohistochemistry. Lovastatin significantly improved performance on both the rotarod and adhesive removal tests before post-injury day 7. Lovastatin also significantly reduced contusion volume (20%) and number of FJB-positive degenerating neurons (35%) at 4 days. These changes were associated with a significant decrease in levels of TNF-alpha and IL-1beta mRNA and protein at the contusion site at 6 h and 4 days, respectively. Our results show that pre-administration of lovastatin improved functional outcomes and reduced extent of brain damage, with a concomitant decrease in tissue levels of TNF-alpha and IL-1beta mRNA and protein. These findings suggest that lovastatin's protective mechanisms may be partly attributed to a dampening of the inflammatory response.

Specific caspase interactions and amplification are involved in selective neuronal vulnerability in Huntington's disease

Huntington's disease (HD) is an autosomal dominant progressive neurodegenerative disorder resulting in selective neuronal loss and dysfunction in the striatum and cortex. The molecular pathways leading to the selectivity of neuronal cell death in HD are poorly understood. Proteolytic processing of full-length mutant huntingtin (Htt) and subsequent events may play an important role in the selective neuronal cell death found in this disease. Despite the identification of Htt as a substrate for caspases, it is not known which caspase(s) cleaves Htt in vivo or whether regional expression of caspases contribute to selective neuronal cells loss. Here, we evaluate whether specific caspases are involved in cell death induced by mutant Htt and if this correlates with our recent finding that Htt is cleaved in vivo at the caspase consensus site 552. We find that caspase-2 cleaves Htt selectively at amino acid 552. Further, Htt recruits caspase-2 into an apoptosome-like complex. Binding of caspase-2 to Htt is polyglutamine repeat-length dependent, and therefore may serve as a critical initiation step in HD cell death. This hypothesis is supported by the requirement of caspase-2 for the death of mouse primary striatal cells derived from HD transgenic mice expressing full-length Htt (YAC72). Expression of catalytically inactive (dominant-negative) forms of caspase-2, caspase-7, and to some extent caspase-6, reduced the cell death of YAC72 primary striatal cells, while the catalytically inactive forms of caspase-3, -8, and -9 did not. Histological analysis of post-mortem human brain tissue and YAC72 mice revealed activation of caspases and enhanced caspase-2 immunoreactivity in medium spiny neurons of the striatum and the cortical projection neurons when compared to controls. Further, upregulation of caspase-2 correlates directly with decreased levels of brain-derived neurotrophic factor in the cortex and striatum of 3-month YAC72 transgenic mice and therefore suggests that these changes are early events in HD pathogenesis. These data support the involvement of caspase-2 in the selective neuronal cell death associated with HD in the striatum and cortex.

Relationship between flow-metabolism uncoupling and evolving axonal injury after experimental traumatic brain injury

Blood flow-metabolism uncoupling is a well-documented phenomenon after traumatic brain injury, but little is known about the direct consequences for white matter. The aim of this study was to quantitatively assess the topographic interrelationship between local cerebral blood flow (LCBF) and glucose metabolism (LCMRglc) after controlled cortical impact injury and to determine the degree of correspondence with the evolving axonal injury. LCMRglc and LCBF measurements were obtained at 3 hours in the same rat from 18F-fluorodeoxyglucose and 14C-iodoantipyrine coregistered autoradiographic images, and compared to the density of damaged axonal profiles in adjacent sections and in an additional group at 24 hours using beta-amyloid precursor protein (beta-APP) immunohistochemistry. LCBF was significantly reduced over the ipsilateral hemisphere by 48 +/- 15% compared with sham-controls, whereas LCMRglc was unaffected, apart from foci of elevated LCMRglc in the contusion margin. Flow-metabolism was uncoupled, indicated by a significant 2-fold elevation in the LCMRglc/LCBF ratio within most ipsilateral structures. There was a significant increase in beta-APP-stained axons from 3 to 24 hours, which was negatively correlated with LCBF and positively correlated with the LCMRglc/LCBF ratio at 3 hours in the cingulum and corpus callosum. Our study indicates a possible dependence of axonal outcome on flow-metabolism in the acute injury stage.

Effect of 5-methoxypsoralen (5-MOP) on cell apoptosis and cell cycle in human hepatocellular carcinoma cell line

The chemopreventive role of 5-methoxypsoralen (5-MOP) in the human hepatocellular carcinoma (HCC) cell line was investigated by studying the regulation of proliferation and apoptosis in HCC (J5) cells. Morphological analysis, cell viability assay, DNA analysis and cell-cycle analysis suggest that there are at least three modes of the suppressive effects shown by 5-MOP: (a) kills J5 cells directly; (b) induces apoptosis by arresting J5 cells at the G2/M phase in the cell cycle; (c) induces apoptosis through an independent pathway with cell-cycle arrest at 24-72 h of exposure. Further immunoblot analysis demonstrated that inhibition of cyclin B1 by 5-MOP may play an important role in G2/M arrest of J5 cells and provides an additional way to prevent cells from entering the M phase and undergoing apoptosis. 5-MOP therefore appears to exert its anticarcinogenic properties by cytotoxic effect, inducing apoptosis and inhibiting proliferation in the human hepatocellular carcinoma cell line.

A ligand-receptor pair that triggers a non-apoptotic form of programmed cell death

Several receptors that mediate apoptosis have been identified, such as Fas and tumor necrosis factor receptor I. Studies of the signal transduction pathways utilized by these receptors have played an important role in the understanding of apoptosis. Here we report the first ligand-receptor pair-the neuropeptide substance P and its receptor, neurokinin-1 receptor (NK(1)R)-that mediates an alternative, non-apoptotic form of programmed cell death. This pair is widely distributed in the central and peripheral nervous systems, and has been implicated in pain mediation and depression, among other effects. Here we demonstrate that substance P induces a non-apoptotic form of programmed cell death in hippocampal, striatal, and cortical neurons. This cell death requires gene expression, displays a non-apoptotic morphology, and is independent of caspase activation. The same form of cell death is induced by substance P in NK(1)R-transfected human embryonic kidney cells. These results argue that NK(1)R activates a death pathway different than apoptosis, and provide a signal transduction system by which to study an alternative, non-apoptotic cell death program.

Treatment of refractory acute leukemia with timed sequential chemotherapy using topotecan followed by etoposide + mitoxantrone (T-EM) and correlation with topoisomerase II levels

A phase I/II clinical study evaluated 17 patients with refractory/recurrent acute leukemia treated with 1.5 mg/m2/day topotecan on days 1-3 followed by etoposide (100 mg/m2/day)+mitoxantrone (10 mg/m2/day) on days 4, 5 and 9, 10. Timed sequential chemotherapy using the topoisomerase I-inhibitor topotecan before the topoisomerase II-inhibitors, etoposide+mitoxantrone (T-EM) treatment is proposed to induce topoisomerase II protein levels and potentiate the cytotoxic activity of the topoisomerase II-directed drugs. Fourteen patients had refractory and three had recurrent acute leukemia. The majority of patients were heavily pre-treated with greater than three re-induction chemotherapy regimens. Ten patients responded to T-EM treatment (59%). Four of seventeen (24%) had a complete remission and one had a partial remission. Four additional patients (24%) who scored complete leukemia clearance had no evidence of disease with complete white and red blood cell recovery but with platelet counts less than 100,000. The lack of platelet recovery in one patient having a partial response was scored as a partial leukemia clearance. The toxicity profile included major non-hematological toxicity including grade 3 mucositis (29%) and neutropenic fever (65%). Paired measurements of intracellular levels of topoisomerase II isoforms alpha and beta in leukemia blast cells (bone marrow) collected before (day 0) and after topotecan treatment (day 4) showed that a relative increase of topoisomerase IIalpha (Topo IIalpha) > or = 40% strongly correlated with response after T-EM treatment. Increased Topo IIalpha levels also corresponded to increased DNA fragmentation. Two patients who had an increase of Topo IIalpha of 20-25% had either a PR or PLC while patients with a < 10% increase showed no response to T-EM treatment. We conclude that timed sequential chemotherapy using topotecan followed by etoposide+mitoxantrone is an effective regimen for patients with refractory acute leukemia, and demonstrate Topo IIalpha protein level increases after topotecan treatment.

[Cloning and functional analysis of glnB from Azospirillum brasilense Yu62]

The glnB gene of A. brasilense Yu62 was determined in a 3.7 kb EcoRI + PstI fragment. The glnA is located downstream of glnB and an ORF for hypothetical protein is on upstream of glnB. The deduced amino acid sequence of PII encoded by glnB is 71%, 77%, 79% and 69% identical to that of K. pneumoniae, Bradyrhizobium japonicum, Rhizobium leguninosarum and E. coli, respectively. A Km-casette was inserted into BglII site of glnB coding region and GlnB- mutant was obtained by homologous recombination. The GlnB- mutant has lost the nitrogenase activity, i.e.: Nif-. For the functional confirmation of glnB gene, a complementary test was carried out and it was shown that C-glnB(glnB::Km/glnB) can restore the nitrogenase activity. When the recombinant plasmid pVK-II which containined the coding region of glnB was introduced into A. brasilense Yu62 and A. brasilense Yu62 DraT-, respectively, the Yu62-II (containing pVK-II) and draT-II(containing pVK-II) showed higher nitrogenase activity than wild type. These results confirmed that glnB plays an important role in the regulation of nitrogen in A. brasilense.

The spatial distribution of macular pigment in humans

PURPOSE

To estimate the distributions in width as well as in density of macular pigment (MP) in humans at different ages, imaging fundus reflectometry was employed as a tool to reach our aim.

METHODS

Imaging fundus reflectometry was used to measure the macular pigment distribution in human eyes with a modified fundus camera to which a cooled CCD camera was attached. The fundus images were taken at 460 nm and 560 nm after the retina was light-adapted to completely bleach rhodopsin. The density of macular pigment was estimated using a model described in the text. The variation in density with retinal eccentricity was fit to Gaussian distribution. The width of MP in retinal eccentricity was estimated by 95% covering area of the distribution profile. A total of 54 normal people served as subjects. They were divided into three groups with ages of 24.8 +/- 2.6 years (N = 24), 40.2 +/- 8.3 years (N = 13) and 67.5 +/- 7.1 years (N = 17) respectively. Statistical t-tests were employed to evaluate the differences in MP density, the half width of MP distributed (HWMPD) in retina with respect to age between the groups. Linear regression was also applied to reveal the relationships of HWMPD distribution with respect to age.

RESULTS

The results indicate that the average MP densities are 0.23 +/- 0.08, 0.22 +/- 0.06 and 0.23 +/- 0.06 density unit (DU) for the young to old age groups. The average MP density is 0.23 +/- 0.07. No statistical significant difference is found in the peak MP density between the groups (all p > 0.05). This result pretty agrees with the data that obtained from others by using optical methods. For the young to old age groups, the average estimated HWMPD are 2.6 degrees +/- 0.5 degrees, 3.1 degrees +/- 0.5 degrees and 4.1 degrees +/- 0.6 degrees respectively. The differences between loci of HWMPD in the three groups are statistically significant with p = 0.0059, p < 0.0001 and p = 0.0001 for young vs. mid-age, young vs. old and mid-age vs. old respectively. Linear regressions for the HWMPD vs. age (r = 0.734, p < 0.001) implies that the macular pigment can gradually accumulate and spread out to the periphery of retina through our life span with an increase rate of approximately 0.03 degrees /year.

CONCLUSIONS

The accumulation of MP is reflected by the broader area in the macula lutea due to age, but no significant change is observed in peak density. The cause of the extension in the macular area with respect to age is unknown.

The involvement of glutamate in recall of the conditioned NK cell response

The molecular mechanisms responsible for the conditioned enhancement of natural killer (NK) cell activity were investigated. The primary goal of the study was to examine the roles of glutamate and gamma-aminobutyric acid (GABA) in recall of the conditioned NK cell response. Both neurochemical blocking assay and high performance liquid chromatography (HPLC) technique were used in the study. Results from the neurochemical blocking assay demonstrated that glutamate but not GABA was required in recall of the conditioned NK cell response. NMDA but not the kainate/AMPA receptors, are believed to be involved. The levels of glutamate that were released and/or taken up also appeared to be critical in that interruption of glutamate release and/or uptake blocked the conditioned NK cell response. Results from the HPLC analysis, however, did not show any significant difference in the glutamate content between the conditioned and control brains.

Induction of Tie-1 and Tie-2 receptor protein expression after cerebral ischemia-reperfusion

Tie-1 and Tie-2 are receptor tyrosine kinases (RTKs) that are exclusively expressed in endothelial cells and play important roles in endothelial cell biology. The authors have reported previously the temporal profiles of Tie-1 and Tie-2 mRNA expression after focal cerebral ischemia-reperfusion. In the current study, the localization of Tie-1/Tie-2 mRNA and proteins were further investigated in the same focal ischemia model. In situ hybridization showed that, after 60-minute ischemia and 72-hour reperfusion, both Tie-1 and Tie-2 mRNA appeared as capillary-like structures in the ischemic middle cerebral artery (MCA) cortex. Western blot analysis showed a biphasic expression of Tie-1 protein in the same region. The first peak, spanning the ischemic and early reperfusion period. was of low intensity and short-lived. The second peak was of greater intensity and spanning the period from 72 to 168 hours after reperfusion. Similarly, Tie-2 expression at the protein level also exhibited a biphasic pattern. Immunohistochemical studies, after 72 hours of reperfusion, showed that although Tie-1 and Tie-2 were detected within the ischemic cortex, they actually were expressed in different populations of endothelial cells in different regions. In agreement with the in situ hybridization study, Tie-1 immunoreactivity appeared as capillary-like structures in cortical layers 2 to 4. Similar capillary-like appearance of Tie-2 immunoreactivity was noted in the outer cortical layers. In addition, Tie-2 immunoreactivity also was observed in cortical layer 6b, where de novo large vessel formation was noted. Cellular colocalization experiments revealed that Tie-2 is expressed in proximity to its antagonist, Angpo-2, as well as basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) in cortical layer 1, where active vessel remodeling was noted. Interestingly, bFGF only partially colocalized with VEGF, suggesting differential roles for these angiogenic factors during vessel remodeling. Tie-1 protein, to a lesser degree, also colocalized with Angpo-2, bFGF, and VEGF in cortical layer 1. Magnetic resonance imaging (MRI) showed increased regional cerebral blood flow (CBF) corresponding to the expression of these angiogenesis gene products. Together, these findings suggest that the evolving expression of angiogenesis genes underlie the robust vascular remodeling after ischemia and reperfusion.

Potentiation of antitumor activity of irinotecan by chemically modified oligonucleotides

Co-administration of synthetic chemically modified oligonucleotides with irinotecan, a selective topoisomerase I inhibitor, provided a significant enhancement in the antitumor activity of irinotecan. The enhancement of antitumor activity of irinotecan with co-administration of chemically modified oligonucleotides was observed in several tumor models--pancreatic cancer (Panc-1), colon cancer (HCT-116) and melanoma (A375). Inhibition of tumor growth in all three models required the co-administration of irinotecan and chemically modified oligonucleotides, but was independent of the nucleotide sequence of the oligonucleotides. The potentiation of antitumor activity was dependent on the dose of irinotecan and chemically modified oligonucleotides administered. The enhancement of antitumor activity of irinotecan was also observed by co-administration of a phosphorothioate oligonucleotide, however, to a lesser extent than did chemically modified oligonucleotides, suggesting that metabolic stability of the oligonucleotide contributes to the enhancement of antitumor activity seen with irinotecan. The co-administration of dextran sulfate sodium with irinotecan showed insignificant potentiation of antitumor activity of irinotecan, suggesting that the enhancement of antitumor activity of irinotecan observed was not a result of polyanionic characteristic of oligonucleotides. Co-administration of irinotecan and chemically modified oligonucleotides did not result in increased toxicity in the tumor models studied. Potentiation of antitumor activity of irinotecan observed with co-administration of oligonucleotides suggests that the oligonucleotides affect the pharmacokinetics and/or metabolism of irinotecan. The use of chemically modified oligonucleotides together with irinotecan may increase the therapeutic index of irinotecan in cancer patients and continued development of such agents should be considered.

Determination of aqueous chlorothalonil with solid-phase microextraction and gas chromatography

Solid-phase microextraction coupled with GC-electron-capture detection was examined to analyze aqueous chlorothalonil residuals. The optimal conditions for chlorothalonil pre-concentration such as fiber polarity, temperature, salt addition, absorption time, as well as the interference were investigated in detail. In addition, the thermal desorption conditions in the injector were also systematically optimized. Experimental results indicated that an extraction with a 100-microm polydimethylsiloxane fiber for 40 min under conditions of 1250 rpm stirring rate, room temperature, and adding high concentration salt offered an optimal result. The thermal desorption of chlorothalonil at 240 degrees C for 3 min (including fiber regeneration) offered the best sensitive detection. A standard addition method for calibration was recommended to reduce the deviation from matrix interference. The proposed method provided a simple and rapid analytical procedure for chlorothalonil in water bodies with detection limits of 2.86 microg/l for distilled water, 3.06 microg/l for ground water, 4.77 microg/l for tap water, and 9.23 microg/l for farm water. The relative standard deviations were all below 3.0% (n=6) besides the farm water being below 9.2%. The calibration graph in the range of 5 to 200 microg/l is linear with very good correlation coefficient (r=0.999), and r=0.983 for farm water. Application was illustrated by the analysis of water samples collected from tap water, ground water and farm water in the southern Taichung area.

Induction of angiogenesis related genes in the contralateral cortex with a rat three-vessel occlusion model

The bFGF/FGFR, VEGF/VEGFR and Angiopoietin/Tie receptor system are crucial for angiogenesis and vascular remodeling. With a rat focal cerebral ischemia model, we previously reported dramatic changes in the vascular density and angiogenesis related genes in the ipsilateral cortex after 60 minutes severe ischemia. While only a small increase in the capillary density was noted in the contralateral cortex with very mild ischemia. In the present study we further reported that only Tie-1 and VEGFR-2 mRNA were significantly changed in the contralateral cortex with a p value of 0.0001 and 0.0168, respectively, and the degree of changes were very small. Interestingly, in contrast to a huge increase in the ipsilateral cortex, Tie-1 mRNA was slowly decreased after the onset of ischemia and stayed below the basal level throughout the remaining periods studied. The mechanism and significance for this decrease is not presently clear. In contrast to the ipsilateral cortex, the Angpo-1/Angpo-2 mRNA ratio was also slightly dropped below the basal level in the contralateral side in most of the ischemia-reperfusion periods studied, which is in line with the notion that small decrease in Angpo-1/Angpo-2 mRNA ratio implied small vascular remodeling activity. It is very likely that increase in this Angpo-1/Angpo-2 ratio is crucial for remodeling into large vessels and increase in Tie-1 may be crucial for capillary density increasing. Nevertheless, the detailed mechanisms and significance of differential expression of these genes and relationship to vascular remodeling remain to be characterized.

LIGHT, a TNF-like molecule, costimulates T cell proliferation and is required for dendritic cell-mediated allogeneic T cell response

LIGHT is a recently identified member of the TNF superfamily and its receptors, herpesvirus entry mediator and lymphotoxin beta receptor, are found in T cells and stromal cells. In this study, we demonstrate that LIGHT is selectively expressed on immature dendritic cells (DCs) generated from human PBMCs. In contrast, LIGHT is not detectable in DCs either freshly isolated from PBMCs or rendered mature in vitro by LPS treatment. Blockade of LIGHT by its soluble receptors, lymphotoxin beta receptor-Ig or HVEM-Ig, inhibits the induction of DC-mediated primary allogeneic T cell response. Furthermore, engagement of LIGHT costimulates human T cell proliferation, amplifies the NF-kappaB signaling pathway, and preferentially induces the production of IFN-gamma, but not IL-4, in the presence of an antigenic signal. Our results suggest that LIGHT is a costimulatory molecule involved in DC-mediated cellular immune responses.

[Molecular cloning and nucleotide sequence of soybean glycinin gene Gy5(A3B4)]

The glycinin gene family encoding the glycinin subunits in soybean plants is composed of at least 5 gene members, i.e.: Gy1-Gy5. A genomic clone containing the Gy5 gene from a genomic library of cv. Williams was isolated by using Gy5 cDNA probe. The complete nucleotide sequence of this gene has been determined. It is 2819 bp long consisting of four exons and three introns. These exons and introns are as follows: exonl(292 bp), intronl(358 bp), exon2(263 bp), intron2(425 bp), exon3(645 bp), intron3(485 bp), exon4(351 bp). The gene encodes 517 amino asids. This is the first time to report the complete Gy5 gene sequence from a genomic library.

Pyrrolo[2,3-d]pyrimidine nucleosides: synthesis and antitumor activity of 7-substituted 7-deaza-2'-deoxyadenosines

A one step synthesis, using the nucleoside 7-iodo-2'-deoxytubercidin (2b) in a Pd(0)/Cu(I)-catalyzed cross coupling reaction furnished a series of 7-alkynyl-2'-deoxytubercidin derivatives. The 7-iodo-, 7-chloro- or 7-bromo 2'-deoxytubercidins 2b-d as well as certain 7-alkynyl derivatives show significant activity against several tumor cell lines, with 7-iodo-2'-deoxytubercidin (2b) as the most effective compound.

Excitotoxicity is required for induction of oxidative stress and apoptosis in mouse striatum by the mitochondrial toxin, 3-nitropropionic acid

Excitotoxicity is implicated in the pathogenesis of several neurologic diseases, such as chronic neurodegenerative diseases and stroke. Recently, it was reported that excitotoxicity has a relationship to apoptotic neuronal death, and that the mitochondrial toxin, 3-nitropropionic acid (3-NP), could induce apoptosis in the striatum. Although striatal lesions produced by 3-NP could develop through an excitotoxic mechanism, the exact relationship between apoptosis induction and excitotoxicity after 3-NP treatment is still not clear. The authors investigated the role of excitotoxicity and oxidative stress on apoptosis induction within the striatum after intraperitoneal injection of 3-NP. The authors demonstrated that removal of the corticostriatal glutamate pathway reduced superoxide production and apoptosis induction in the denervated striatum of decorticated mice after 3-NP treatment. Also, the N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801, prevented apoptosis in the striatum after 3-NP treatment for 5 days, whereas the non-NMDA receptor antagonist, 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo(F)quinoxaline, was ineffective. The authors also evaluated the initial type of neuronal death by 3-NP treatment for different durations from 1 to 5 days. In early striatal damage, apoptotic neuronal death initially occurred after 3-NP treatment. Our data show that excitotoxicity related to oxidative stress initially induces apoptotic neuronal death in mouse striatum after treatment with 3-NP.

Comparison of in vitro activities of camptothecin and nitidine derivatives against fungal and cancer cells

The activities of a series of camptothecin and nitidine derivatives that might interact with topoisomerase I were compared against yeast and cancer cell lines. Our findings reveal that structural modifications to camptothecin derivatives have profound effects on the topoisomerase I-drug poison complex in cells. Although the water-soluble anticancer agents topotecan and irinotecan are less active than the original structure, camptothecin, other derivatives or analogs with substitutions that increase compound solubility have also increased antifungal activities. In fact, a water-soluble prodrug appears to penetrate into the cell and release its active form; the resulting effect in complex with Cryptococcus neoformans topoisomerase I is a fungicidal response and also potent antitumor activity. Some of the compounds that are not toxic to wild-type yeast cells are extremely toxic to the yeast cells when the C. neoformans topoisomerase I target is overexpressed. With the known antifungal mechanism of a camptothecin-topoisomerase I complex as a cellular poison, these findings indicate that drug entry may be extremely important for antifungal activity. Nitidine chloride exhibits antifungal activity against yeast cells through a mechanism(s) other than topoisomerase I and appears to be less active than camptothecin analogs against tumor cells. Finally, some camptothecin analogs exhibit synergistic antifungal activity against yeast cells in combination with amphotericin B in vitro. Our results suggest that camptothecin and/or nitidine derivatives can exhibit potent antifungal activity and that the activities of camptothecin derivatives with existing antifungal drugs may be synergistic against pathogenic fungi. These new compounds, which exhibit potent antitumor activities, will likely require further structural changes to find more selective activity against fungal versus mammalian cells to hold promise as a new class of antifungal agents.

Myocardial effects of beta-agonist stimulation in rats with chronic left ventricular dysfunction treated with an angiotensin-converting enzyme inhibitor

BACKGROUND

This study measured morphological and hemodynamic changes and renin-angiotensin responsiveness of the left ventricle (LV) to beta-agonist stimulation in a Sprague-Dawley rat model of myocardial dysfunction produced by coronary artery ligation.

METHODS

The LV function and papillary muscle mechanics were measured after 12 weeks of captopril treatment (2 g/l in drinking water) following left coronary artery ligation or a sham operation. Fifty-two rats were divided into three groups: those with sham operations, those with small infarcts (infarct size [IS] < 30% LV) and those with large infarcts (IS > or = 30% LV).

RESULTS

The results showed that LV end-diastolic pressures were elevated in the large-infarct group regardless of treatment with the angiotensin-converting enzyme inhibitor (ACEI), and the LV weight was reduced in the ACEI-treated rats. In addition, the uninfarcted LV posterior papillary muscle of the large-infarct rats showed an impaired response to isoproterenol stimulation, including the developed tension, positive and negative rate of tension development, time to peak tension, and time to half relaxation.

CONCLUSION

Chronic captopril treatment improved isoproterenol-stimulated muscle isometric function in rats following myocardial infarction, possibly through the beta-receptor pathway.

Effect of dGTP concentration on human and CHO telomerase

Human telomerase produces a long ladder of six-base repeat additions to a primer, while CHO telomerase primarily adds only one or two repeat additions to a primer. Under the standard assay conditions, the concentration of dGTP is very low, so we investigated the effects of increasing dGTP concentration on human and CHO telomerase activities. Increasing dGTP concentration over a range of 1.5-50 microM caused the human telomerase to produce longer primer extension products until products were so large that no ladder pattern was apparent. Increasing dGTP concentration resulted in CHO telomerase producing one to eight repeat additions, though still not as many repeats as produced by human telomerase even under low dGTP conditions. CHO telomerase produced a six-base ladder pattern comparable to human telomerase only after raising the dGTP concentration to 500 microM under conditions in which the dATP concentration was low. Primer challenge experiments showed the human telomerase exhibited approximately 100% processivity at both low and high concentrations of dGTP, and thus increasing dGTP concentration appeared to affect only the extension rate. In contrast, CHO telomerase exhibited low processivity under low concentrations of dGTP and increased processivity at higher dGTP concentrations. One explanation for the low processivity of CHO was found in CHO telomerase's inability to extend the GGTTAG permuted primer under nonprocessive conditions, while able to extend the other five permuted primers. Competition studies of different permuted primers indicated that the GGTTAG primer cannot interact with the nonprocessive CHO telomerase. A model is proposed for explaining the nonprocessive behavior of CHO telomerase.

Functional roles of the extracellular segments of the sodium channel alpha subunit in voltage-dependent gating and modulation by beta1 subunits

Voltage-gated sodium channels consist of a pore-forming alpha subunit associated with beta1 subunits and, for brain sodium channels, beta2 subunits. Although much is known about the structure and function of the alpha subunit, there is little information on the functional role of the 16 extracellular loops. To search for potential functional activities of these extracellular segments, chimeras were studied in which an individual extracellular loop of the rat heart (rH1) alpha subunit was substituted for the corresponding segment of the rat brain type IIA (rIIA) alpha subunit. In comparison with rH1, wild-type rIIA alpha subunits are characterized by more positive voltage-dependent activation and inactivation, a more prominent slow gating mode, and a more substantial shift to the fast gating mode upon coexpression of beta1 subunits in Xenopus oocytes. When alpha subunits were expressed alone, chimeras with substitutions from rH1 in five extracellular loops (IIS5-SS1, IISS2-S6, IIIS1-S2, IIISS2-S6, and IVS3-S4) had negatively shifted activation, and chimeras with substitutions in three of these (IISS2-S6, IIIS1-S2, and IVS3-S4) also had negatively shifted steady-state inactivation. rIIA alpha subunit chimeras with substitutions from rH1 in five extracellular loops (IS5-SS1, ISS2-S6, IISS2-S6, IIIS1-S2, and IVS3-S4) favored the fast gating mode. Like wild-type rIIA alpha subunits, all of the chimeric rIIA alpha subunits except chimera IVSS2-S6 were shifted almost entirely to the fast gating mode when coexpressed with beta1 subunits. In contrast, substitution of extracellular loop IVSS2-S6 substantially reduced the effectiveness of beta1 subunits in shifting rIIA alpha subunits to the fast gating mode. Our results show that multiple extracellular loops influence voltage-dependent activation and inactivation and gating mode of sodium channels, whereas segment IVSS2-S6 plays a dominant role in modulation of gating by beta1 subunits. Evidently, several extracellular loops are important determinants of sodium channel gating and modulation.

VEGI, a new member of the TNF family activates nuclear factor-kappa B and c-Jun N-terminal kinase and modulates cell growth

Recently a new member of the human tumor necrosis factor (TNF) family named as VEGI was reported. However, very little is known about the biological activities displayed by this cytokine. In this report, we show that in myeloid cells VEGI activated the transcription factor kappa B (NF-kappa B) as determined by the electrophoretic mobility shift assay, induced degradation of I kappa B alpha, and nuclear translocation of p65 subunit of NF-kappa B. VEGI also activated NF-kappa B-dependent reporter gene expression. In addition, VEGI activated c-Jun N-terminal kinase. When examined for growth modulatory effects, VEGI inhibited the proliferation of breast carcinoma (MCF-7), epithelial (HeLa), and myeloid (U-937 and ML-1a) tumor cells; and activated caspase-3 leading to PARP cleavage. VEGI-induced cytotoxicity was potentiated by inhibitors of protein synthesis. VEGI also induced proliferation of normal human foreskin fibroblast cells. The activity of VEGI could neither be neutralized by antibodies against TNF, nor could it compete with TNF binding, indicating that the activity of VEGI is not due to TNF and it binds to a distinct receptor. These results suggest that VEGI, a new member of the TNF family, has a signaling pathway similar to TNF and is most likely a multifunctional cytokine.

Targeted expression of human CuZn superoxide dismutase gene in mouse central nervous system

Copper zinc superoxide dismutase (CuZnSOD) is an important enzyme for the detoxification of reactive oxygen species. Particularly in the central nervous system (CNS), reactive oxygen species are often associated with acute brain injuries and chronic neurodegeneration. It has been demonstrated in vivo that there is an inverse correlation between CuZnSOD activity and neuronal death after acute brain injury. To further understand the protective role of CuZnSOD upon neurons, we have generated transgenic mouse lines with targeted expression of the human CuZnSOD gene (SOD1) that is driven by a rat neuron-specific enolase gene promoter in neurons of the CNS. The transgenic SOD1 expression was restricted to the CNS identified by reverse transcriptase polymerase chain reaction and SOD gel electrophoresis assays. The CuZnSOD activity was significantly increased in the brain stem of the transgenic mice. Immunostaining of human CuZnSOD activity showed that Purkinje cells in the cerebellar cortex were the most intensely stained neurons in the CNS of the transgenic mice.

Release of mitochondrial cytochrome c and DNA fragmentation after cold injury-induced brain trauma in mice: possible role in neuronal apoptosis

Recent studies have shown that release of mitochondrial cytochrome c is a critical step in the apoptosis process. In this study, we examined the subcellular distribution of the cytochrome c protein after cold injury (CI), in which apoptosis is assumed to participate. Western blotting and immunohistochemistry showed cytosolic cytochrome c as early as 1 h after CI, and correspondingly, there was a reduction in mitochondrial cytochrome c after injury. Neuronal distribution of cytosolic cytochrome c was shown by double staining with a neuronal nuclear marker by immunohistochemistry. A significant amount of DNA laddering was detected 4 h after CI, and increased in a time-dependent manner. These data suggest that early cytochrome c release from mitochondria may contribute to apoptosis induction after traumatic brain injury.