Mechanisms of cell death induced by nitric oxide and peroxynitrite in Calu-1 cells

S-nitrosoglutathione (GSNO) is an important physiological redox form of nitric oxide (NO) and serves as an NO-releasing compound. 3-Morpholinosydnonimine hydrochloride (SIN-1) produces NO and superoxide anion (O(2)(·-)) which results in the formation of peroxynitrite (ONOO(-)). We investigate the cytotoxicity, cell death mechanisms and gene expression of NO and ONOO(-) in human lung epithelial cells show NO induced apoptosis and DNA genomic fragmentation. Whereas, ONOO(-) induced cell death more characteristic of necrosis than apoptosis. The concentrations of GSNO and SIN-1 required to cause death in 50% of cells were greater than 1 mM. Several gene products are important in controling the apoptotic and necrotic processes. Of these, bcl-2, bax and hsp 70 were studied. The level of expression of bcl-2 was dramatically decreased in cells treated with SIN-1 or GSNO, while the expression level of bax, the heterodimer of bcl-2, did not significant change. In addition, a roughly two-fold increase of hsp 70 was found in cells treated with SIN-1. There were no significant changes in hsp 70 levels in cells treated with GSNO.

Selenium-dependent glutathione peroxidase-GI is a major glutathione peroxidase activity in the mucosal epithelium of rodent intestine

Gpx2 mRNA, encoding a selenium-dependent glutathione peroxidase (GPX-GI), has been found to be highly expressed in the gastrointestinal tract (GI) mucosal epithelium. In this study, we show that GPX-GI is produced in the mucosal epithelium of the adult rat GI tract and that the activity levels are comparable to that from GPX-1. Post-mitochondrial supernatant GPX activity from the mucosal epithelium of the complete length of the small intestine was partially purified. A sample enriched for putative GPX-GI was fractionated by SDS-polyacrylamide gel electrophoresis. Polypeptides of 21 kDa and 22 kDa were digested with trypsin. After resolving the tryptic peptides by high pressure liquid chromatography (HPLC), the major peaks were analyzed for their amino acid sequence by Microflow-HPLC-Tandem Mass Spectrometry and automated Edman degradation sequencing. Both methods revealed that the 21-kDa sample contained rat GPX-GI determined by the sequence homology with the deduced mouse GPX-GI polypeptide sequence. Rat GPX-1 was also detected in the samples. AntiGPX-GI and antiGPX-1 antibodies were used to determine the distribution of the respective isoenzyme activities along the length of the intestine and with respect to the crypt to villus axis in rats. GPX-GI and GPX-1 activities were uniformly distributed in the middle and lower GI tract and with respect to the crypt to villus axis. GPX-GI activity accounted nearly the same percentage of the total GPX activity as GPX-1 in all of the these compartments. Studies on the distal ileum segment of wildtype and Gpx1 gene knockout mice showed that GPX-GI activity was also at parity with GPX-1 in the mucosal epithelium of this segment.

Cellular glutathione peroxidase is the mediator of body selenium to protect against paraquat lethality in transgenic mice

The antioxidative role of Se-dependent cellular glutathione peroxidase (EC 1.11.1.9, GPX1) in vivo has not been established. Our objective was to determine the effects of GPX1 knockout or overexpression on the susceptibility of mice to paraquat toxicity and the contributions of GPX1, compared with other selenoproteins and vitamin E, to body defenses against such acute oxidative stress. Four experiments were conducted using 111 GPX1 knockout or overexpressing mice and the respective controls. Mice were fed diets supplemented with Se (as sodium selenite) at 0-0.4 mg/kg and/or all-rac-alpha-tocopheryl acetate at 0-75 mg/kg before intraperitoneal injections of 12.5, 50 or 125 mg paraquat/kg body weight. All mice that received 50 or 125 mg paraquat/kg died spontaneously, and the survival time of mice was (independent of dietary levels of Se per se or alpha-tocopheryl acetate) solely a function of tissue GPX1 activity (P < 0.001). Severe acute pulmonary interstitial necrosis was found only in the GPX1 overexpressing mice and the controls that had extended survival time. Thiobarbituric acid reacting substances in postmortem liver inversely correlated with the tissue GPX1 activity and dietary levels of Se and/or alpha-tocopheryl acetate. In contrast, all mice that received 12.5 mg paraquat/kg survived and were killed 2 wk after the injection for tissue collection. Compared with the saline injection, this low dose of paraquat resulted in greater (P < 0.001) liver and lung F2-isoprostanes in both the GPX1 knockout mice and the controls. However, there was no difference in plasma alanine transaminase (EC 2.6.1.2) activity or overt injuries in liver, lung and kidney in either group. Our data indicate that GPX1 is the major, if not the only, metabolic form of body Se that protects mice against the lethal oxidative stress caused by high levels of paraquat; it seems less important, however, in protecting mice against the moderate oxidative stress by the low level of paraquat.

Nuclear multiparameter flow cytometric DNA analysis of human brain tumors: correlation of DNA content with tumor histology and clinical behavior

BACKGROUND

Using fresh surgical specimens of brain tumors to investigate cellular DNA content is uncommon. The aim of this study is to elucidate the relationship among cellular nuclear DNA content, tumor histology, and tumor clinical behavior of various tumors of the central nervous system.

METHODS

Multiparameter flow cytometry (FACStar, Becton-Dickinson, San Jose, CA) was randomly applied to analyze 40 fresh surgical specimens from brain tumors. Histologically, there were 19 cases of benign tumors and 21 cases of malignant tumors.

RESULTS

DNA distribution profiles in the benign tumors revealed 15 cases of diploidy and four cases of aneuploidy, while the malignant tumors had eight cases of diploidy and 13 cases of aneuploidy (p < 0.01). The mean DNA index (DI) in benign tumors was 1.13 +/- 0.27 and in malignant tumors 1.43 +/- 0.48 (p < 0.05). The mean proliferative index (PI) in benign tumors was 10.27 +/- 5.46% and 18.44 +/- 8.98% in malignant tumors (p < 0.05). Clinically, 10 patients had postoperative recurrence. The PI in recurrent and nonrecurrent tumors was 17.83 +/- 11.13% and 13.20 +/- 7.19%, respectively (p < 0.05). The 1-year cumulative survival rate in benign tumors was 78.9%, and 57.1% in malignant tumors (p < 0.05).

CONCLUSIONS

Malignant tumors had a significantly higher incidence of aneuploid DNA histograms, a higher DNA index, and a higher proliferative index. Tumors with a high PI had a higher incidence of recurrence and a lower survival rate. Multiparameter DNA analysis by flow cytometry provides a valuable diagnostic aid for the histopathologic differentiation of human brain tumors.

Clinical evaluation of C7 spinal nerve transection: 21 patients with at least 2 years' follow-up

We have performed C7 spinal nerve transfer to treat root injury of the brachial plexus since 1989. Out of a total of 43 patients, 21 have been followed up for at least 2 years. Evaluation of the effect of C7 transection included clinical examination, intraoperative C7 stimulation, LIDO Workset machine and electrophysiological studies to test C7 innervated muscles, and histochemical analysis of the anterior and posterior division of the upper trunk using acetylcholinesterase stain. Nearly half of the study group (48%) reported no significant sensory changes and most patients (81%) did not notice any weakness of the limb following C7 transection. Some patients did experience sensory and motor abnormalities which were most frequent during the first postoperative month, improved during the 2nd month and in most cases resolved in the 3rd postoperative month. The only longer persistent abnormality was the triceps reflex, which becomes weak or absent. We also found that intraoperative C7 stimulation was a useful predictor of possible post-transection morbidity. Subclinical deficits, detected by the LIDO workset machine and by electro-physiological studies, were quite common. Histochemical analysis revealed that the posterior division of C7 had more motor fibres than the anterior division.

Transgenic models for the study of lung antioxidant defense: enhanced manganese-containing superoxide dismutase activity gives partial protection to B6C3 hybrid mice exposed to hyperoxia

To investigate the role of manganese-containing superoxide dismutase (MnSOD) in lung antioxidant defense, lines of transgenic B6C3 hybrid mice carrying human MnSOD transgenes under the transcriptional control of a human beta-actin promoter were established. Expression studies demonstrated that the human MnSOD transgene in line TgHMS66 is expressed and functional. The cellular distribution of the transgene product in the lungs was further examined by immunocytochemical analysis. Increased immunoreactive MnSOD was found in mitochondria of lung type I epithelial cells, type II epithelial cells, capillary endothelial cells, and fibroblasts. Furthermore, the magnitude of increase in mitochondrial labeling density of type II cells of nontransgenic, hemizygous, and homozygous transgenic littermates was proportional to the increased lung activity of MnSOD found in these mice. Transgenic mice over-expressing MnSOD did not have enhanced survival relative to controls when exposed to > 99% oxygen. However, when exposed to 90% oxygen, the transgenic mice had a small but statistically significant increase in survival time. Our results indicate that when the beta-actin promoter is used to increase activity of MnSOD it provides modest protection to B6C3 mice against hyperoxic lung injury.

Reduced fertility in female mice lacking copper-zinc superoxide dismutase

Copper-zinc superoxide dismutase (CuZn-SOD) is believed to play a major role in the first line of antioxidant defense by catalyzing the dismutation of superoxide anion radicals to form hydrogen peroxide and molecular oxygen. Recent studies have shown that missense mutations in this gene contribute, evidently through a gain-of-function mechanism, to about 20% of familial amyotrophic lateral sclerosis. To define further the physiologic role of this enzyme, a model of mice deficient in this enzyme was generated using gene targeting technology. Mice lacking this enzyme were apparently healthy and displayed no increased sensitivity to hyperoxia. However, they exhibited a pronounced susceptibility to paraquat toxicity. Most surprisingly, female homozygous knock-out mice showed a markedly reduced fertility compared with that of wild-type and heterozygous knock-out mice. Further studies revealed that although these mice ovulated and conceived normally, they exhibited a marked increase in embryonic lethality. These data, for the first time, suggest a role of oxygen free radicals in causing abnormality of female reproduction in mammals.

Preoperative embolization of meningiomas: comparison of superselective and subselective techniques

We retrospectively compared the efficacy of preoperative superselective and subselective embolization for intracranial meningiomas. Between January and December 1996, 22 patients (7 men, 15 women, mean age 51 +/- 15.5 yr) underwent superselective embolization with 45 to 150 mm polyvinyl alcohol particles after superselective catheterization of the feeding vessels with a microcatheter system. Another 30 patients (12 men, 18 women, mean age 50 +/- 12.9 yr) underwent subselective embolization between January and December 1995 with 150 to 300 mm Gelfoam particles after catheterization of the terminal external carotid artery just proximal to the orifice of the maxillary artery with a 4- or 5-F angiocatheter. The mean intraoperative blood loss (918 versus 1450 mL, p < 0.05), amount of blood transfused (4.9 versus 7.5 units, p = 0.09), and surgical resection time (422 versus 529 min, p < 0.05) were all lower in the superselective group than in the subselective group, while the occurrence of fresh ischemic necrosis (59% versus 53%, p = 0.68), hemorrhage (77% versus 60%, p = 0.19), and embolic material (55% versus 13%, p < 0.05) on pathologic examination were higher in the superselective group. No procedure-related complications occurred in the superselective group, whereas two patients in the subselective group had postoperative scalp necrosis. Our findings show that superselective embolization is more effective than subselective embolization for preoperative endovascular devascularization of meningiomas, with significant reductions in intraoperative blood loss and surgery time. Preoperative embolization of meningiomas, if indicated, should be done with the superselective technique whenever feasible.

Administration of dexamethasone induces proteinuria of glomerular origin in mice

The administration of glucocorticoids has been reported to exacerbate proteinuria in a few patients with glomerulonephritis. This effect has not been well recognized, and the pathogenetic mechanism responsible for this phenomenon remains to be clarified. In this study, we observed that a high daily oral dose (0.5 mg/kg body weight) of dexamethasone was capable of inducing overt proteinuria in mice, beginning on day 5 and persisting for a 19-day duration. One fourth of mice also intermittently presented with slight hematuria beginning on day 12. Renal lesions in the dexamethasone-treated mice, which were killed on day 23, were characterized by mild mesangial expansion, segmental or global hyalinosis/sclerosis in deep cortical glomeruli, and focal tubular changes. No glomerular inflammatory cell infiltration or proliferative lesion was noted in any of the mice. Ultrastructural features of glomeruli included mesangial widening characterized by either an increase of mesangial matrix, dilated mesangial channels filled with slightly electron-dense material or mesangial lysis-like appearance showing intracytoplasmic microcysts filled with electron-lucent material, and evidence to support injury of endothelial cells, erythrocytes, and podocytes. An immunofluorescence study revealed enhanced glomerular deposition of IgG, IgA, IgM, and fibrinogen (P < 0.001, compared with normal control mice), but no glomerular C3 deposition was identified in any of the dexamethasone-treated mice. Charge analysis showed no impairment in anionic property of glomerular tufts in the dexamethasone-treated mice. In addition, the dexamethasone-induced proteinuria was greatly attenuated by treatment with a low molecular weight heparin, although it was not reduced by an angiotensin-converting enzyme inhibitor. Data from these experiments suggest that a large dose of glucocorticoids is potentially nephrotoxic. Alteration of a size-dependent permeability may predominantly contribute to the dexamethasone-induced proteinuria. However, the effect of glomerular hyperfiltration may be only partially involved in the pathogenesis of this dexamethasone-induced glomerulopathy in mice.

Cervical ecchordosis physaliphora: CT and MR features

We report a case of cervical ecchordosis physaliphora in an elderly man who presented with hemihypoaesthesia and contralateral hemiparesis. MRI showed a well defined, non-enhancing extradural mass lesion on the dorsal surface of the odontoid process of the axis. The lesion was of intermediate signal intensity on T1 weighted images and of low signal intensity on T2 weighted images. CT showed a small bony defect on the adjacent cortex of the odontoid process. Recognition of the imaging features of ecchordosis physaliphora is helpful in suggesting the diagnosis and differentiating the lesion from chordoma.

Clinical and pathological characteristics of secondary thyroid cancer

Although up to 24% of metastatic cancers have been reported to spread to the thyroid gland, metastases to the thyroid are not detected in clinical practice in most cases. The prognosis is poor when metastatic cancer to the thyroid occurs. The aim of this study was to examine the clinical presentation, cytopathological findings, and clinical course of secondary cancers of the thyroid. The medical records of a total of 1013 histopathologically verified thyroid cancer patients treated during the period from January 1977 to December 1995 in Chang Gung Medical Center in Linkou were analyzed retrospectively. There were 14 patients (1.4% of all thyroid cancers) with secondary cancers of the thyroid with a mean age of 55.3 +/- 16.7 years. All these patients underwent thyroid ultrasonography and a fine-needle aspiration cytology of the thyroid (FNAC) before biopsy or surgical treatment. Tissue diagnosis was obtained by biopsy or necropsy in 12 or by thyroidectomy specimens in 2 patients. Most of the patients died within 9 months of diagnosis except for 2 patients who were lost to follow-up after transferring to another hospital and 1 patient with lymphoma. Before the surgical diagnosis, there were only 7 patients who metastatic neoplasms to the thyroid gland were diagnosed by FNAC. Anaplastic thyroid carcinoma was diagnosed in 5 patients. Benign nodule was diagnosed in 1 patient and lymphoma in another patient. Most of these patients had widespread metastases to many organs, as well as the thyroid gland. As a result these patients had very short survival times. Delayed diagnosis of the thyroid metastasis was the main reason for the short survival period. In conclusion, most of the metastatic lesions presented as an advanced stage of primary cancers. FNAC was a useful tool in the diagnosis. Histopathological diagnosis by surgical open biopsy is needed for the final diagnosis.

Acute suppurative thyroiditis and aggressive malignant thyroid tumors: differences in clinical presentation

BACKGROUND AND OBJECTIVES

Aggressive malignant thyroid tumors (AMTT) may mimic the clinical symptoms and signs of acute suppurative thyroiditis (AST) in the early course of the disease process. Our objective was to analyze the clinical features of these two conditions, to assess the best way of early diagnosis, and to propose proper treatment.

METHODS

We retrospectively reviewed and analyzed the clinical features of 30 patients, who had similar clinical pictures of AST and were managed at Chang Gung Memorial Medical Center in Linkou, Taiwan, during the period from 1983 to 1996. These patients were consequently diagnosed as either AST or AMTT. The data were analyzed by the Mann-Whitney U, chi-square and Fisher's exact tests.

RESULTS

Among the 30 patients, 25 patients (Male/Female (M/F) ratio = 9/16) were diagnosed as having AST and 5 (M/F ratio = 1/4) as AMTT. After statistical analysis we concluded that the presence of the following factors, namely, older age at diagnosis (P = 0.0155), history of dysphonia (P = 0.0325), right thyroid lobe involvement (P = 0.0151), large size of lesions (P = 0.0013), presence of anemia (P = 0.0075), and sterile pus cultures from thyroid aspirates (P = 0.0013) were cause to suspect a malignancy if the condition did not improve after antibiotics. Delay in diagnosis and management of AMTT may result in a poor prognosis (P = 0.0082).

CONCLUSION

Due to the high mortality rate of AMTT, we should closely observe the patients with poor prognostic variables of acute thyroiditis. Earlier detection and aggressive surgical intervention for AMTT might improve the outcome.

Primary diffusely infiltrative adenocarcinoma of the colon and rectum

BACKGROUND

Primary diffusely infiltrative colorectal adenocarcinoma is rare. About 100 cases have been reported in the literature. The mucosal alterations in this type of tumor and their clinicopathological characteristics in relation to survival are not clear.

METHODS

We retrospectively reviewed 30 cases of primary diffusely infiltrative colorectal adenocarcinoma operated upon in a single institution.

RESULTS

Eighteen (60%) of these 30 patients were women. The average age at diagnosis was 47.4 (SD, 19.3) years. Eighteen tumors (60%) were located in the rectum. The tumors could be classified into two major types. A type 1 tumor had minimal mucosal alteration and no discrete ulcer. A type 2 tumor was associated with a discrete ulcer. The type 1 tumor was more frequently associated with intracellular or extracellular mucin production and stage IV disease. Hematogenous spread (including peritoneal carcinomatosis) was more frequently seen in type 1 than in the type 2 tumors (61% vs. 18%, p = 0.013). The overall median cancer-specific survival time was 15 (SE, 3; 95% confidence interval, 10-21) months. TNM stage is the only significant factor in predicting outcome (p = 0.016). When compared with stages II and III, the odds of death for stage IV was 2.9 (95% confidence interval: 1.1-7.4).

CONCLUSION

Diffusely infiltrative colorectal cancer can be separated into two subtypes according to the presence of a discrete ulcer. The type 1 tumor (without a discrete ulcer) was associated with a higher frequency of hematogenous spread. TNM Stage was the only important clinicopathological factor in determining outcome.

Glutathione peroxidase knockout mice are susceptible to myocardial ischemia reperfusion injury

BACKGROUND

To test our hypothesis that intracellular antioxidant enzymes constitute a cellular defense against acute stress, we studied myocardial ischemia reperfusion injury in the setting of reduced level of glutathione peroxidase using GSHPx-1 gene knockout mice.

METHODS

Knockout mice were developed by disrupting the coding sequence of GSHPx-1 gene after inserting a neomycin resistance gene derived from pMCIpol A into the EcoRI site located in exon 2. Isolated perfused hearts were prepared from two groups of mice-knockout and nontransgenic controls. A 4-0 silk was attached to the apex of the heart which in turn was attached to a force transducer. Hearts were perfused by the Langendorff mode, and after 20 minutes of stabilization subjected to 30 minutes of ischemia followed by 2 hours of reperfusion. The force developed by the heart (DF) and the first derivative of DF (dF/dt) were recorded. Creatine kinase (CK) release was measured in the perfusate and the infarct size was measured at the end of each experiment.

RESULTS

For both GSHPx-1 knockout and nontransgenic control groups, DF and dF/dt were significantly lower during early postischemic reperfusion compared with baseline, but these values were significantly higher for the control group than the knockout mice throughout most of the reperfusion period. CK release from the heart increased during reperfusion for both groups, but this increase was significantly lower for the control group. The infarct size was also smaller for the control mice as compared with knockouts.

CONCLUSIONS

The results indicate that the knockout mice are more susceptible to ischemia reperfusion injury, suggesting the importance of GSHPx-1 gene in myocardial protection from ischemic reperfusion injury.

The Colorectal Cancer Recurrence Support (CARES) System

Colorectal cancer has risen in incidence to become the second commonest form of cancer in Singapore. The primary treatment is surgery but up to 50% of patients still suffer from recurrence of the cancer after surgery. Early identification of recurrence will increase the effectiveness of therapy and the survival of patients. This paper describes the CARES (Cancer Recurrence Support) System, whose objective is to predict the recurrence of colorectal cancer, using Case-based Reasoning (CBR), and supported by other techniques such as data mining and natural language processing. The CARES System employs CBR to compare and contrast between the new and past colorectal cancer patient cases, and makes inferences based on those comparisons to determine the high risk patient groups. The features and functionality of the system are described.

Intracranial meningeal melanocytoma: CT and MRI

We report the MRI and CT findings of an intracranial meningeal melanocytoma (IMM) arising from Meckel's cave and review the imaging characteristics of IMM. On CT, IMM constantly appear as well-circumscribed, isodense to slightly dense, extra-axial tumours with homogeneous contrast enhancement. This appearance is non-specific and similar to that of meningiomas or small neuromas. On MRI, the signal of IMM is strongly related to the amount of melanin pigment: the more melanin, the more shortening of T1 and T2 relaxation times. Only when it shows as a homogeneous mass, bright on T1 and dark on T2 weighting, can a specific diagnosis of a melanin-containing tumour be made. However, this still cannot provide a distinction between IMM and malignant meningeal melanoma.

Clinical presentations and predictive variables of thyroid microcarcinoma with distant metastasis

BACKGROUND

Thyroid microcarcinoma is not an uncommon disorder. The purpose of this study is to analyze the clinical presentation and predictive factors for patients with thyroid microcarcinomas who have distant metastases.

METHODS

We retrospectively reviewed and analyzed the clinical variables of 97 patients with thyroid microcarcinoma during the period from 1977 to 1995. The patients were divided into 2 groups representing patients with and without distant metastases. These data were analyzed by the Mann-Whitney U, chi 2 and Fisher's exact tests.

RESULTS

Of the 97 patients with thyroid microcarcinomas, there were 6 (6.2%) cases (F/M = 5/1) with distant metastases. Among them, 4 cases were papillary carcinomas and 2 cases were follicular carcinomas. The parameters: age at diagnosis (P = 0.0137), one month postoperative serum thyroglobulin (Tg) level (P = 0.0215), cervical lymph node metastasis (P = 0.0097), and follicular cell type (P = 0.0079), were determined to be factors predictive for distant metastases by statistical analysis. There were no statistical differences between gender (P = 0.5781), postoperative 131I uptake (P = 0.1238), tumor size (P = 0.0571), preoperative thyroid function (P = 0.4425), fine-needle aspiration cytology (FNAC) (P = 0.9723), preoperative thyroid scan (P = 0.9765), and operative methods (P = 0.1060) between these two groups.

CONCLUSIONS

Most thyroid microcarcinomas presented with relatively benign clinical courses, but patients with adverse predictive factors need more aggressive interventions to improve outcome.

Pathogenetic implications of DNA nondiploidy in colorectal cancers

PURPOSE

Several studies propose that proximal and distal colorectal cancers have a different pathogenesis. We tested the hypothesis using flow cytometric DNA analysis.

METHODS

DNA analysis was performed in 719 patients with colorectal cancer. In addition, histopathologic data were re-evaluated in a blinded fashion by a single pathologist.

RESULTS

Distal tumors were more often nondiploid than were proximal tumors (61 vs. 49 percent; P = 0.015). Compared with the proximal tumor, distal tumors were smaller (P = 0.0001) and had less desmoplastic reaction (39 vs. 53 percent; P = 0.0001). Tumor location had no significant associations with the remaining parameters, including mucin production, perineural invasion, blood/lymphatic vessel invasion, lymphocytic infiltration, histologic grade, tumor stage, gross appearance, age, and gender.

CONCLUSIONS

The unequal distribution of ploidy suggests distinct pathogenetic mechanisms at proximal and distal sites.

Expression and chromosomal mapping of mouse Gpx2 gene encoding the gastrointestinal form of glutathione peroxidase, GPX-GI

GPX-GI is a cytosolic tetrameric Se-dependent glutathione peroxidase, similar in properties to GPX-1. Unlike the almost ubiquitous GPX-1, GPX-GI is mainly expressed in the epithelium of gastrointestinal tract. GPX-GI contributes to at least fifty percent of GPX activity in rodent small intestinal epithelium. The total GPX activity consists of at least 70% of selenium-dependent GPX activity in this compartment. By analyzing a panel of mouse interspecies DNA from the Jackson Laboratory's backcross resource, we mapped Gpx2 gene to mouse chromosome 12 between D12Mit4 and D12Mit5, near the Ccs1 locus which contains a colon cancer susceptibility gene. A pseudogene, Gpx2-ps is mapped to mouse chromosome 7. Comparison of Gpx2 gene expression in three pairs of C57BL/6Ha and ICR/Ha mice which are respectively resistant and sensitive to dimethylhydrazine-induced colon cancer, we found a higher Gpx2 mRNA level in C57BL/6Ha colon than ICR/Ha colon. Interestingly, a lower level of GPX activity is found in the resistant strain of mice. Because GPX-1 has three times higher specific activity than GPX-GI, our data suggest that the decreased GPX activity may result from a higher level of Gpx2 gene expression in those cells co-express Gpx1 gene.

Stability of curcumin in buffer solutions and characterization of its degradation products

The degradation kinetics of curcumin under various pH conditions and the stability of curcumin in physiological matrices were investigated. When curcumin was incubated in 0.1 M phosphate buffer and serum-free medium, pH 7.2 at 37 degrees C, about 90% decomposed within 30 min. A series of pH conditions ranging from 3 to 10 were tested and the result showed that decomposition was pH-dependent and occurred faster at neutral-basic conditions. It is more stable in cell culture medium containing 10% fetal calf serum and in human blood; less than 20% of curcumin decomposed within 1 h, and after incubation for 8 h, about 50% of curcumin is still remained. Trans-6-(4'-hydroxy-3'-methoxyphenyl)-2,4-dioxo-5-hexenal was predicted as major degradation product and vanillin, ferulic acid, feruloyl methane were identified as minor degradation products. The amount of vanillin increased with incubation time.

Cellular glutathione peroxidase knockout mice express normal levels of selenium-dependent plasma and phospholipid hydroperoxide glutathione peroxidases in various tissues

Selenium-dependent cellular glutathione peroxidase (GPX1) knockout [GPX1(-)] mice were derived from 129/SVJ x C57BL/6 hybrid mice by microinjecting C57BL/6 blastocysts with recombinant embryonic stem cells carrying a target mutation in the GPX1 gene. Experiment 1 was conducted to determine the effects of the GPX1 knockout on the susceptibility of mice to dietary vitamin E and Se deficiency and on the expression of the Se-dependent plasma glutathione peroxidase (GPX3) and phospholipid hydroperoxide glutathione peroxidase (GPX4), and the Se-independent glutathione S-transferase (GST). Eleven GPX1(-) and 11 control mice (5 wk old, six males and five females) were fed a Se-deficient, Torula yeast basal diet (0.02 mg Se/kg, no supplemental vitamin E) or the basal diet supplemented with 0.5 mg Se/kg (as Na2SeO3) for 13 wk. Experiment 2 was conducted to determine the effect of the GPX1 knockout on the total Se concentration in the liver of Se-adequate mice. Six GPX1(-) and four control mice (5 wk old, half males and females) were fed the basal diet supplemented with 0.2 mg Se/kg and 15 mg of all-rac-alpha-tocopheryl acetate/kg for 5 wk. There was no difference in body weight gain or apparent susceptibility to dietary vitamin E and Se deficiency between the GPX1(-) and control mice. Knockout of GPX1 resulted in almost complete abolishment of GPX1 activity in various tissues, but had no effect on the GPX3 or GPX4 mRNA level and activity or the GST activity in several tissues at either level of dietary Se. The liver total Se concentration in the Se-adequate GPX1(-) mice was only 42% of that in the controls (P < 0. 0001). These results indicate that GPX1 is expressed independently of GPX3 or GPX4 and represents approximately 60% of the total hepatic Se in Se-adequate mice.

Use of Riu stain in the immediate interpretation of bronchial brushing cytology. Comparison with Papanicolaou stain and histology

OBJECTIVE

To determine the usefulness of Riu stain in the immediate interpretation of cytologic material from bronchoscopic brushings and its accuracy in the diagnosis of lung malignancies.

STUDY DESIGN

A prospectively comparative study between Riu and Papanicolaou stain with pathologic control was conducted. Eighty-six patients with central lung lesions, visible during fiberoptic bronchoscopy, were studied. Endobronchial biopsies and brushings were performed at the time of the same procedure.

RESULTS

The diagnostic accuracy of Riu stain for malignancy was 97%, with a sensitivity of 99%, specificity of 85%, positive predictive value of 97% and negative predictive value of 92%. As for the Papanicolaou technique, the diagnostic accuracy for malignancy was 97%, with a sensitivity of 97%, specificity of 92%, positive predictive value of 99% and negative predictive value of 86%. The overall cytologic typing accuracy of Riu stain was 86%, which was comparable with that of Papanicolaou stain (90%, P = .48). Both techniques are more accurate in the diagnosis of squamous carcinoma, small cell carcinoma and adenocarcinoma than in large cell carcinoma.

CONCLUSION

Riu stain is rapid, simple to use and, most important, accurate for the identification of lung malignancies. It can increase the diagnostic success rate, prevent unnecessary repeat bronchoscopies and lower related complications.

Mice deficient in cellular glutathione peroxidase develop normally and show no increased sensitivity to hyperoxia

Glutathione peroxidase, a selenium-containing enzyme, is believed to protect cells from the toxicity of hydroperoxides. The physiological role of this enzyme has previously been implicated mainly using animals fed with a selenium-deficient diet. Although selenium deficiency also affects the activity of several other cellular selenium-containing enzymes, a dramatic decrease of glutathione peroxidase activity has been postulated to play a role in the pathogenesis of a number of diseases, particularly those whose progression is associated with an overproduction of reactive oxygen species, found in selenium-deficient animals. To further clarify the physiological relevance of this enzyme, a model of mice deficient in cellular glutathione peroxidase (GSHPx-1), the major isoform of glutathione peroxidase ubiquitously expressed in all types of cells, was generated by gene-targeting technology. Mice deficient in this enzyme were apparently healthy and fertile and showed no increased sensitivity to hyperoxia. Their tissues exhibited neither a retarded rate in consuming extracellular hydrogen peroxide nor an increased content of protein carbonyl groups and lipid peroxidation compared with those of wild-type mice. However, platelets from GSHPx-1-deficient mice incubated with arachidonic acid generated less 12-hydroxyeicosatetraenoic acid and more polar products relative to control platelets at a higher concentration of arachidonic acid, presumably reflecting a decreased ability to reduce the 12-hydroperoxyeicosatetraenoic acid intermediate. These results suggest that the contribution of GSHPx-1 to the cellular antioxidant mechanism under normal animal development and physiological conditions and to the pulmonary defense against hyperoxic insult is very limited. Nevertheless, the potential antioxidant role of this enzyme in protecting cells and animals against the pathogenic effect of reactive oxygen species in other disorders remains to be defined. The knockout mouse model described in this report will also provide a new tool for future study to distinguish the physiological role of this enzyme from other selenium-containing proteins in mammals under normal and disease states.

Induction of glutathione depletion, p53 protein accumulation and cellular transformation by tetrachlorohydroquinone, a toxic metabolite of pentachlorophenol

Glutathione (GSH) conjugate formation with tetrachlorohydroquione (TCHQ) and the GSH content in vivo were measured by capillary zone electrophoresis. A more than 60% depletion of GSH content was found in liver tissue of mice treated with TCHQ. In addition, p53 protein accumulation and DNA fragmentation was induced by TCHQ. A two-stage model of chemical transformation of mouse embryonic fibroblasts was used to elucidate the transformation activity of TCHQ in vitro, and a 33% foci formation efficiency was found at the concentration of 5 microM. GSH depletion caused by TCHQ could abolish the protective ability of the cell against reactive oxygen species provided by GSH. When DNA was damaged, p53 protein accumulated in the nucleus and, in the case of severe damage, initiated apoptosis. TCHQ's ability to cause GSH depletion and DNA damage may play a role in the cytotoxic and genotoxic properties of its metabolic precursor, PCP.

Cerebral sparganosis: increased uptake of technetium-99m-HMPAO

Cerebral sparganosis is an extremely rare intracranial parasitic infectious disease. We report findings of 99mTc-HMPAO cerebral perfusion SPECT in a case with cerebral sparganosis. SPECT revealed an irregularly shaped area with markedly increased 99mTc-HMPAO uptake in the parasitic infectious region of the cerebrum. Both white and gray matter was involved, the white matter involved predominantly. Decreased perfusion to the right cerebellum, suggesting cross cerebellar diaschisis, was also demonstrated. This article illustrates that cerebral sparganosis is one of the causes of increased 99mTc-HMPAO uptake in the cerebrum and should be considered clinically if present.