Anoxic depolarization of rat hippocampal slices is prevented by thiopental but not by propofol or isoflurane

BACKGROUND

There is strong evidence to suggest that anoxic depolarization (AD) is an important factor in hypoxia/ischaemia-induced neural damage. Treatments that prevent the occurrence of AD may be useful in providing neuronal protection against hypoxia. The current study was designed to determine whether general anaesthetics which have been suggested to 'induce prophylaxis' against hypoxia can attenuate the incidence of AD.

METHODS

The effects of anoxia (3 min) on evoked extracellularly recorded field potentials of CA1 neurons in rat hippocampal slices were assessed in the absence and presence of the i.v. general anaesthetics thiopental and propofol and the volatile anaesthetic isoflurane.

RESULTS

In the absence of anaesthetics, AD occurred in 81% of the preparations tested. Thiopental (2 x 10(-4) M) significantly reduced the incidence of AD (16%, P=0.0006). In comparison, propofol (2 x 10(-4) M) and isoflurane (1.5 vol%) were ineffective (69% and 60%, respectively). Furthermore, in the presence of thiopental, the population spike amplitude recovered with and without AD (90% and 94% of pre-anoxic value, respectively) following 3 min anoxia.

CONCLUSION

The prophylactic effect of thiopental against hypoxia might be induced, in part, by preventing the generation of AD.

Overview of mammalian zinc transporters

In recent years, a number of mammalian zinc transporters have been identified, and candidate genes are rapidly growing. These transporters are classified into two families: ZIP (ZRT, IRT-like protein) and CDF (cation diffusion facilitator). ZIP members facilitate zinc influx into the cytosol, while CDF members facilitate its efflux from the cytosol. Molecular characterization of the transporters has brought about major advances in our understanding of their physiological functions. Zinc metabolism is regulated primarily through zinc-dependent control of transcription, translation, and intracellular trafficking of transporters. Analyses of mice whose zinc transporter genes have been genetically disrupted and of the naturally occurring mutant mice with symptoms related to abnormal zinc metabolism have provided compelling evidence that some zinc transporters play critical roles in zinc homeostasis. In this review, we review the literature of mammalian zinc transporters with emphasis on very recent findings and elicit integrative knowledge of zinc homeostasis.

[A case of steroid-induced glaucoma after radial keratotomy]

BACKGROUND

We report a patient who was diagnosed as having steroid-induced glaucoma after radial keratotomy(RK) and suffered from severe visual field defect.

CASE

A 29-year-old man underwent RK for both eyes. After the operation, he was treated for six months with topical medication including 0.1% and 0.01% betamethasone without measuring intraocular pressure(IOP). When he consulted an ophthalmologist, his IOP was 43 mmHg in the right eye and 51 mmHg in the left eye. At our initial examination, his IOP was 8 mmHg in the right eye and 10 mmHg in the left eye with 750 mg acetazolamide peroral, 0.5% timolol maleate, and latanoprost eyedrops. There were RK 16 incisions on the cornea and we found severe glaucomatous visual field loss. Finally we performed trabeculotomy in both eyes for IOP control with conservative therapy.

CONCLUSION

As the keratorefractive surgery becomes popular, we must be careful of problems, such as steroid-induced glaucoma, and the change of refraction following the change of IOP.

Case of radiation-induced esophageal ulcer worsened after endoscopic biopsy

Esophageal ulcer is one of the most important late complications of the esophagus treated with radiation therapy, especially with intraluminal brachytherapy. We encountered a patient with esophageal cancer treated with external radiation therapy and intraluminal brachytherapy, who developed radiation ulcer and who had severe dysphagia soon after endoscopic biopsy of the ulcer edge. A 55-year-old man was diagnosed as esophageal cancer without symptoms. He received 60 Gy/30 Fr of external radiation therapy and 12 Gy/3 Fr of intraluminal brachytherapy at a point of 5 mm in depth from the mucosa surface. He developed an asymptomatic esophageal ulcer 13 months after treatment, and endoscopic biopsy was obtained from the edge of the ulcer. Thereafter, swallowing difficulties appeared, and endoscopy revealed severe esophageal stenosis and a deep ulcer. A possibility that the biopsy contributed to worsening the ulcer can be considered. Except for cases where relapse is apparent, endoscopic biopsy is considered to be avoided.

Early-onset, rapidly progressive familial tauopathy with R406W mutation

An early-onset and rapidly progressive familial tauopathy with R406W mutation is described. The patient was a 47-year-old man who first presented with psychiatric symptoms followed by overt dementia at age 52 and died 1 year later. Postmortem study revealed tangle-associated neuronal degeneration, accentuated in the medial temporal lobe. R406W mutation was determined by sequence analysis and immunocytochemically with anti-mutant tau antibody.

Additional gene therapy with Ad5CMV-p53 enhanced the efficacy of radiotherapy in human prostate cancer cells

PURPOSE

The aim of this study was to investigate the efficacy of combination therapy of ionizing radiation (IR) and adenoviral p53 gene therapy and to evaluate its molecular mechanisms.

METHODS AND MATERIALS

Two human prostate cancer cell lines, DU145 and PC-3 cells, containing different types of p53 gene mutations, were investigated. The recombinant adenovirus vector containing the wild-type p53 gene (Ad5CMV-p53) was used for this study. Cells were irradiated (in 0, 2, 4, and 6 Gy, 300 cGy/min) and after 12 h of irradiation, the cells were infected with various doses of Ad5CMV-p53 (0-40 multiplicity of infection [MOI]). Cytotoxicity was determined by clonogenic assay. The molecular mechanisms were evaluated by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), apoptotic cell detection, and cell cycle analysis.

RESULTS

The cell growth inhibition in DU145 (p53-mutated) cells by IR was strongly enhanced by additional Ad5CMV-p53 infection in a viral dose-dependent manner. In DU145 cells, IR alone induced minimal p53 mRNA expression. However, IR combined with Ad5CMV-p53 infection stimulated significant increase in p53 mRNA expression supplemented with Bax and p21 mRNA expressions. In PC-3 (p53-null), IR induced Bax and p21 mRNA expression, while the combination effects were observed in p53, Bax, and p21 mRNA expression. Apoptotic cell deaths were rarely observed after IR alone (DU145: 3%, PC-3: 5%). However, after combination therapy, the proportion of apoptotic cells greatly increased (sevenfold in DU145 cells, and twice in PC-3 cells). G1 cell cycle arrest was observed after Ad5CMV-p53 infection and the combination in both cell lines.

CONCLUSION

In this study, we demonstrated that the combination of IR and Ad5CMV-p53 gene therapy resulted in remarkable synergistic effects in human prostate cancer cells. This combination therapy could be one of the optimal treatment strategies for radioresistant prostate cancer.

Associations of plasma endothelin concentration with carotid atherosclerosis and asymptomatic cerebrovascular lesions in patients with essential hypertension

We studied the association of endothelin (ET)-1 with carotid atherosclerosis and asymptomatic cerebrovascular lesions in patients with essential hypertension. Neurologically normal patients with essential hypertension (n=293; 138 male, 155 female; mean age, 65 years) and age-matched control subjects (n=242) were studied with B-mode ultrasonography of the common and internal carotid arteries and magnetic resonance imaging of the brain. Plasma ET-1 was measured by enzyme immunoassay. Hypertensive patients were divided into groups with carotid plaques and low ET-1 concentrations (< 0.75 pg/ml; PL group); carotid plaques and mid-range ET-1 (0.75 to 1.55 pg/ml; PM group); carotid plaques and high ET-1 (> or = 1.55 pg/ml; PH group); no plaques and low ET-1 (NPL); no plaques and mid-range ET-1 (NPM); and no plaques and high ET-1 (NPH). Overall, ET-1 concentrations were significantly higher in patients than in control subjects. Carotid plaque prevalence was significantly related to ET-1 in hypertensive patients. ET-1 showed a significant positive relationship with the number of asymptomatic lacunar infarcts of the brain in hypertensive patients with carotid plaques (rho=0.48, p<0.001). No significant relationship was seen between ET-1 and periventricular hyperintensity scores in patients with plaques. ET-1 did not show a relationship to either brain lesion type in patients without carotid plaques. Thus, ET-1 may foster asymptomatic lacunar cerebral infarcts by promoting carotid atherosclerosis in patients with essential hypertension.

Drug-resistant human bladder-cancer cells are more sensitive to adenovirus-mediated wild-type p53 gene therapy compared to drug-sensitive cells

We investigated the therapeutic potential and molecular mechanism of adenovirus-mediated wt p53 gene therapy for drug-resistant human bladder cancers. KK47, a human bladder-cancer cell line, along with the drug-resistant sublines KK47/DDP10, KK47/DDP20 (cisplatin-resistant) and KK47/ADM (doxorubicin-resistant) were used for the experiments. All 4 KK47 cell lines had genetically normal p53 genes. Using an in vitro cytotoxicity assay, the drug-resistant cell lines were more sensitive to Ad-CMV-p53 cell killing than the KK47 parental cell line. Ad-CMV-p53 induced higher levels of p53 protein and mRNA in the drug-resistant cell lines than in the parental cell line and, consequently, higher levels of p21 and Bax mRNA, which resulted in higher percentages of G(1) cell-cycle arrest and apoptosis. The higher efficiencies of adenoviral gene transfer in the drug-resistant cell lines were confirmed by X-gal staining after infection with Ad-CMV-beta-gal. In conclusion, adenovirus-mediated wt p53 gene therapy was more effective in the drug-resistant bladder-cancer cell lines than in the drug-sensitive bladder-cancer cell line.

Quantitative analysis of gene expressions of vascular endothelial growth factor-related factors and their receptors in renal cell carcinoma

Vascular endothelial growth factor (VEGF)-related factors are believed to regulate angiogenesis, an essential event in the growth of solid tumors. In this study, we investigated the expression of VEGF-related factor genes (VEGF, VEGF-B, and VEGF-C) and their receptor genes (VEGFR-1 and VEGFR-2) in renal cell carcinoma (RCC). There were significant differences in the expression level of VEGF, VEGFR-1 and VEGFR-2 between RCC and the corresponding normal renal tissue. The expression level of VEGF in the tumor tissue significantly correlated with those of VEGFR-1 and VEGFR-2. Expression levels VEGF-B and VEGF-C genes were not significantly different between RCC and normal renal tissue. A moderate to high protein expression for VEGF, VEGFR-1, and VEGFR-2 was observed in both the tumor cells and the endothelial cells, whereas the protein expression was low for VEGF-B and VEGF-C. The present results suggested that VEGF and its receptors VEGFR-1 and VEGFR-2 cooperates to play a crucial role in the angiogenesis of RCC, while VEGF-B and VEGFR-C may not. Furthermore, since VEGFR-1 and VEGFR-2 proteins were expressed in the tumor cells as well as in the endothelial cells, these receptors may also be responsible for the progression of RCC.

Reciprocal regulation of tissue-type and urokinase-type plasminogen activators in the differentiation of murine preadipocyte line 3T3-L1 and the hormonal regulation of fibrinolytic factors in the mature adipocytes

Adipose tissue expresses a variety of genes including tumor necrosis factor alpha and type-1 plasminogen activator inhibitor (PAI-1); and these factors, produced by adipocytes, may be associated with the risk of coronary events in obesity. In this study, we characterized the production of fibrinolytic factors including tissue-type plasminogen activator (tPA), urokinase-type PA (uPA), and PAI-1 in the differentiation of preadipocytes, and examined the hormonal regulation of these fibrinolytic factors in mature adipocytes. Mouse 3T3-L1 preadipocytes were employed as a model of adipocytes. Adipocyte differentiation was induced by insulin, dexamethasone, and 3-isobutyl-1-methyl xanthine (IBMX). alpha-Glycerophosphate dehydrogenase (GPDH) activity and glucose transporter 4 (GLUT4) mRNA, indices for adipocyte maturation, were induced on Day 4, and gradually increased. GPDH activity reached its maximum level on Day 14. The level of tPA, a major PA in preadipocytes, dramatically decreased with differentiation. On the other hand, that of uPA reciprocally increased. PAI-1 production was also dramatically induced concomitant with differentiation. In mature adipocytes, uPA production was dominant (25 microg/ml/24 h vs. 0.8 microg/ml/24 h for tPA). Total PA activity in the mature adipocytes was reduced by insulin or dexamethasone, but not by glucagon. Insulin, IBMX, and dexamethasone significantly decreased both uPA and tPA production, and increased PAI-1 production. Glucagon had no effect on the production of these fibrinolytic factors. Our results reveal that uPA is one of the markers for the differentiation of 3T3-L1 cells and that insulin, IBMX, and dexamethasone are potent regulators of the fibrinolytic activity in differentiated 3T3-L1 cells, reciprocally affecting PA and PAI-1 levels in them.

BAG-1M, an isoform of Bcl-2-interacting protein BAG-1, enhances gene expression driven by CMV promoter

BAG-1M, one of the isoforms of BAG-1, was reported to bind to DNA and stimulate general transcription when cells were stressed by heat shock (Zeiner, M., et al., Proc. Natl. Acad. Sci. USA 96, 10194-10199, 1999). Here we show that BAG-1M binds and enhances transcriptional activity of Cytomegalovirus (CMV) early gene promoter under unstressed conditions. This activity is unique to BAG-1M in that other isoforms, BAG-1S and BAG-1L, are much weaker in this activity, although all of the isoforms share common ubiquitin-like domain and BAG domain interacting with Hsp70/Hsc70. Deletion analysis of BAG-1M showed that C-terminal BAG domain is necessary to enhance the CMV promoter activity, suggesting that interaction with Hsp70/Hsc70 proteins may mediate this function. Another mutation in N-terminus, BAG-1M K(2-4)A, lost DNA binding capacity and majority of the promoter-enhancing activity. Our study demonstrates that both N-terminal DNA binding site and C-terminal Hsp70/Hsc70 binding site of BAG-1M play an important role in enhancing the CMV promoter activity.