Overexpression of Cox-2 in Human Osteosarcoma Cells Decreases Proliferation and Increases Apoptosis

Overexpression of cyclooxygenase-2 (COX-2) is generally considered to promote tumorigenesis. To investigate a potential role of COX-2 in osteosarcoma, we overexpressed COX-2 in human osteosarcoma cells. Saos-2 cells deficient in COX-2 expression were retrovirally transduced or stably transfected with murine COX-2 cDNA. Functional expression of COX-2 was confirmed by Northern and Western analyses and prostaglandin production. Overexpression of COX-2 reduced cell numbers by 50% to 70% compared with controls. Decreased proliferation in COX-2-overexpressing cells was associated with cell cycle prolongation in G(2)-M. Apoptosis, measured by both Annexin V binding assay and terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling staining, was increased in cells overexpressing COX-2, and the increase was not reversed by treatment with NS-398, indicating that the effects were not mediated by prostaglandins. Retroviral COX-2 overexpression in two other human osteosarcoma cell lines, U2OS and TE85, also decreased cell viability. However, in the human colon carcinoma HCT-116 cell line, which is deficient in COX-2, retroviral overexpression of COX-2, at similar efficiency as in Saos-2 cells, increased resistance to apoptosis. Reactive oxygen species (ROS), measured by flow cytometry, were increased by COX-2 overexpression in Saos-2 cells but not in HCT-116 cells. Inhibition of peroxidase activity, but not of COX activity, blocked the ROS increase. Antioxidants blocked the increase in ROS and the increase in apoptosis due to COX-2 overexpression in Saos-2 cells. Our results suggest that (a) COX-2 overexpression in osteosarcoma cells may increase resistance to tumorigenesis by increasing ROS to levels that decrease cell viability and (b) the effects of COX-2 overexpression are cell type/tissue dependent.

theta Isoform of protein kinase C alters barrier function in intestinal epithelium through modulation of distinct claudin isotypes: a novel mechanism for regulation of permeability

Using monolayers of intestinal Caco-2 cells, we discovered that the isoform of protein kinase C (PKC), a member of the "novel" subfamily of PKC isoforms, is required for monolayer barrier function. However, the mechanisms underlying this novel effect remain largely unknown. Here, we sought to determine whether the mechanism by which PKC- disrupts monolayer permeability and dynamics in intestinal epithelium involves PKC--induced alterations in claudin isotypes. We used cell clones that we recently developed, clones that were transfected with varying levels of plasmid to either stably suppress endogenous PKC- activity (antisense, dominant-negative constructs) or to ectopically express PKC- activity (sense constructs). We then determined barrier function, claudin isotype integrity, PKC- subcellular activity, claudin isotype subcellular pools, and claudin phosphorylation. Antisense transfection to underexpress the PKC- led to monolayer instability as shown by reduced 1) endogenous PKC- activity, 2) claudin isotypes in the membrane and cytoskeletal pools ( downward arrowclaud-1, downward arrowclaud-4 assembly), 3) claudin isotype phosphorylation ( downward arrow phospho-serine, downward arrow phospho-threonine), 4) architectural stability of the claudin-1 and claudin-4 rings, and 5) monolayer barrier function. In these antisense clones, PKC- activity was also substantially reduced in the membrane and cytoskeletal cell fractions. In wild-type (WT) cells, PKC- (82 kDa) was both constitutively active and coassociated with claudin-1 (22 kDa) and claudin-4 (25 kDa), forming endogenous PKC-/claudin complexes. In a second series of studies, dominant-negative inhibition of the endogenous PKC- caused similar destabilizing effects on monolayer barrier dynamics, including claudin-1 and -4 hypophosphorylation, disassembly, and architectural instability as well as monolayer disruption. In a third series of studies, sense overexpression of the PKC- caused not only a mostly cytosolic distribution of this isoform (i.e., <12% in the membrane + cytoskeletal fractions, indicating PKC- inactivity) but also led to disruption of claudin assembly and barrier function of the monolayer. The conclusions of this study are that PKC- activity is required for normal claudin assembly and the integrity of the intestinal epithelial barrier. These effects of PKC- are mediated at the molecular level by changes in phosphorylation, membrane assembly, and/or organization of the subunit components of two barrier function proteins: claudin-1 and claudin-4 isotypes. The ability of PKC- to alter the dynamics of permeability protein claudins is a new function not previously ascribed to the novel subfamily of PKC isoforms.

theta Isoform of protein kinase C alters barrier function in intestinal epithelium through modulation of distinct claudin isotypes: a novel mechanism for regulation of permeability

Using monolayers of intestinal Caco-2 cells, we discovered that the isoform of protein kinase C (PKC), a member of the "novel" subfamily of PKC isoforms, is required for monolayer barrier function. However, the mechanisms underlying this novel effect remain largely unknown. Here, we sought to determine whether the mechanism by which PKC- disrupts monolayer permeability and dynamics in intestinal epithelium involves PKC--induced alterations in claudin isotypes. We used cell clones that we recently developed, clones that were transfected with varying levels of plasmid to either stably suppress endogenous PKC- activity (antisense, dominant-negative constructs) or to ectopically express PKC- activity (sense constructs). We then determined barrier function, claudin isotype integrity, PKC- subcellular activity, claudin isotype subcellular pools, and claudin phosphorylation. Antisense transfection to underexpress the PKC- led to monolayer instability as shown by reduced 1) endogenous PKC- activity, 2) claudin isotypes in the membrane and cytoskeletal pools ( downward arrowclaud-1, downward arrowclaud-4 assembly), 3) claudin isotype phosphorylation ( downward arrow phospho-serine, downward arrow phospho-threonine), 4) architectural stability of the claudin-1 and claudin-4 rings, and 5) monolayer barrier function. In these antisense clones, PKC- activity was also substantially reduced in the membrane and cytoskeletal cell fractions. In wild-type (WT) cells, PKC- (82 kDa) was both constitutively active and coassociated with claudin-1 (22 kDa) and claudin-4 (25 kDa), forming endogenous PKC-/claudin complexes. In a second series of studies, dominant-negative inhibition of the endogenous PKC- caused similar destabilizing effects on monolayer barrier dynamics, including claudin-1 and -4 hypophosphorylation, disassembly, and architectural instability as well as monolayer disruption. In a third series of studies, sense overexpression of the PKC- caused not only a mostly cytosolic distribution of this isoform (i.e., <12% in the membrane + cytoskeletal fractions, indicating PKC- inactivity) but also led to disruption of claudin assembly and barrier function of the monolayer. The conclusions of this study are that PKC- activity is required for normal claudin assembly and the integrity of the intestinal epithelial barrier. These effects of PKC- are mediated at the molecular level by changes in phosphorylation, membrane assembly, and/or organization of the subunit components of two barrier function proteins: claudin-1 and claudin-4 isotypes. The ability of PKC- to alter the dynamics of permeability protein claudins is a new function not previously ascribed to the novel subfamily of PKC isoforms.

Do cyclooxygenase-2 knockout mice have primary hyperparathyroidism?

The absence of cyclooxygenase-2 (COX-2) activity in vitro reduces differentiation of both bone-forming and bone-resorbing cells. To examine the balance of COX-2 effects on bone in vivo, we studied COX-2 knockout (KO) and wild-type (WT) mice. After weaning, KO mice died 4 times faster than WT mice, consistent with reports of progressive renal failure in KO mice. Among KO mice killed at 4 months of age, some had renal failure with marked secondary hyperparathyroidism, but others appeared healthy. On the assumption that renal failure was not inevitable in COX-2 KO mice and that phenotypic differences might increase with age, we studied KO mice surviving to 10 months of age with serum creatinine levels similar to those of WT mice. In 10-month-old male KO mice, serum calcium and PTH, but not phosphorus, levels were increased compared with those in WT mice. 1,25-Dihydroxyvitamin D(3) levels were markedly elevated in KO mice. Skeletal analysis showed small nonsignificant decreases in cortical bone density by BMD and either an increase (distal femur, by microcomputed tomography) or no difference (distal femur, by static histomorphometry) in trabecular bone density in KO mice. There was a trend toward increased percent osteoblastic and osteoclastic surfaces, and on dynamic histomorphometry, the rates of trabecular bone formation and mineral apposition were increased in KO mice relative to WT mice. Similar trends were observed for most parameters in 10-month-old female COX-2 KO mice. However, rates of trabecular bone formation and mineral apposition were increased in 10-month-old WT females compared with males and did not increase further in female KO mice. These data suggest that COX-2 KO mice with intact renal function have primary hyperparathyroidism, and that effects of increased PTH and 1,25-dihydroxyvitamin D(3) to increase bone turnover may compensate for the absence of COX-2.

Toxicity and detoxification of lipid-derived aldehydes in cultured retinal pigmented epithelial cells

Age-related macular degeneration (ARMD) is the leading cause of blindness in the developed world and yet its pathogenesis remains poorly understood. Retina has high levels of polyunsaturated fatty acids (PUFAs) and functions under conditions of oxidative stress. To investigate whether peroxidative products of PUFAs induce apoptosis in retinal pigmented epithelial (RPE) cells and possibly contribute to ARMD, human retinal pigmented epithelial cells (ARPE-19) were exposed to micromolar concentrations of H2O2, 4-hydroxynonenal (HNE) and 4-hydroxyhexenal (HHE). A concentration- and time-dependent increase in H2O2-, HNE-, and HHE-induced apoptosis was observed when monitored by quantifying DNA fragmentation as determined by ELISA, flow cytometry, and Hoechst staining. The broad-spectrum inhibitor of apoptosis Z-VAD inhibited apoptosis. Treatment of RPE cells with a thionein peptide prior to exposure to H2O2 or HNE reduced the formation of protein-HNE adducts as well as alteration in mitochondrial membrane potential and apoptosis. Using 3H-HNE, various metabolic pathways to detoxify HNE by ARPE-19 cells were studied. The metabolites were separated by HPLC and characterized by ElectroSpray Ionization-Mass Spectrometry (ESI-MS) and gas chromatography-MS. Three main metabolic routes of HNE detoxification were detected: (1) conjugation with glutathione (GSH) to form GS-HNE, catalyzed by glutathione-S-transferase (GST), (2) reduction of GS-HNE catalyzed by aldose reductase, and (3) oxidation of HNE catalyzed by aldehyde dehydrogenase (ALDH). Preventing HNE formation by a combined strategy of antioxidants, scavenging HNE by thionein peptide, and inhibiting apoptosis by caspase inhibitors may offer a potential therapy to limit retinal degeneration in ARMD.

Biphasic effect of prostaglandin E2 on osteoclast formation in spleen cell cultures: role of the EP2 receptor

We examined the effect of PGE2 on OC formation from spleen cells treated with M-CSF and RANKL. PGE2 decreased OC number at 5-6 days of culture and increased OC number, size, and resorptive activity at 7-8 days. A selective EP2 receptor agonist mimicked these effects. Deletion of the EP2 receptor or depletion of T-cells abrogated the increase in OC number.

INTRODUCTION

Prostaglandin E2 (PGE2) has been reported to increase osteoclast (OC) number in spleen cells cultured with RANKL and macrophage-colony-stimulating factor (M-CSF). In this study, we examined the time course of PGE2 effects on spleen cells cultured with RANKL and M-CSF. We then investigated which PGE receptors and cell types were involved in these effects.

MATERIALS AND METHODS

Spleen cells were cultured from wildtype C57BL/6 mice and EP2 or EP4 receptor-deficient (-/-) and wildtype (+/+) mice on a mixed genetic background. Spleen cells were cultured with M-CSF and RANKL for 5-9 days with or without PGE2 or selective agonists for the four PGE2 receptors (EP1A, EP2A, EP3A, or EP4A). Some cultures were performed using T-cell-depleted spleen cells. OC number and size were quantitated. OC apoptosis and pit formation were measured at 7 or 8 days.

RESULTS

PGE2 decreased the number of OCs formed in the presence of RANKL and M-CSF at 5-6 days of culture and increased OC number at 8-9 days compared with cultures without PGE2. PGE2 also increased OC size at 7 and 8 days, decreased apoptosis of OC at 7 days, and increased pit formation at 8 days. EP1A or EP4A had no effect on OC. EP3A decreased OC number. EP2A mimicked effect of PGE2. EP2(-/-) spleen cells showed no increase in OC number in response to PGE2, whereas deletion of EP4 had no effect. Depletion of T-cells abrogated the late increase of OC number.

CONCLUSIONS

We conclude that PGE2 has an initial inhibitory effect on OC formation in spleen cell cultures, possibly mediated by both EP2 and EP3 receptors, and a later stimulatory effect, mediated by the EP2 receptor, possibly acting on T-cells.

Extracellular calcium induces COX-2 in osteoblasts via a PKA pathway

We have shown that extracellular calcium [Ca(+2)](e) induces cyclooxygenase-2 (COX-2) expression and prostaglandin E(2) (PGE(2)) production via an ERK signaling pathway in osteoblasts. In this study, we examined the roles of protein kinase C (PKC) and A (PKA) signaling pathways in the [Ca(+2)](e) induction of COX-2 in primary calvarial osteoblasts from mice transgenic for -371 bp of the COX-2 promoter fused to a luciferase reporter. Neither PKC specific inhibitors nor downregulation of the PKC pathway by phorbol myristate acetate (PMA) affected the [Ca(+2)](e) stimulation of COX-2 mRNA or promoter activity. In contrast, PKA inhibitors, used at doses that inhibited forskolin-stimulated luciferase activity by 90%, reduced [Ca(+2)](e)-stimulated COX-2 mRNA expression and promoter activity by 80-90%. [Ca(+2)](e) also stimulated a 2- to 3-fold increase in cAMP production. Hence, the [Ca(+2)](e) induction of COX-2 mRNA expression and promoter activity was independent of the PKC pathway and dependent on the PKA signaling pathway.

Critical role of the atypical {lambda} isoform of protein kinase C (PKC-{lambda}) in oxidant-induced disruption of the microtubule cytoskeleton and barrier function of intestinal epithelium

Oxidant injury to epithelial cells and gut barrier disruption are key factors in the pathogenesis of inflammatory bowel disease. Studying monolayers of intestinal (Caco-2) cells, we reported that oxidants disrupt the cytoskeleton and cause barrier dysfunction (hyperpermeability). Because the lambda isoform of protein kinase C (PKC-lambda), an atypical diacylglycerol-independent isozyme, is abundant in parental (wild type) Caco-2 cells and is translocated to the particulate fractions upon oxidant exposure, we hypothesized that PKC-lambda is critical to oxidative injury to the assembly and architecture of cytoskeleton and the intestinal barrier function. To this end, Caco-2 cells were transfected with an inducible plasmid, a tetracycline-responsive system, to create novel clones stably overexpressing native PKC-lambda. Other cells were transfected with a dominant-negative plasmid to stably inhibit the activity of native PKC-lambda. Cells were exposed to oxidant (H(2)O(2)) +/- modulators. Parental Caco-2 cells were treated similarly. We then monitored barrier function (fluorescein sulfonic acid clearance), microtubule cytoskeletal stability (confocal microscopy, immunoblotting), subcellular distribution of PKC-lambda (immunofluorescence, immunoblotting, immunoprecipitation), and PKC-lambda isoform activity (in vitro kinase assay). Monolayers were also processed to assess alterations in tubulin assembly, polymerized tubulin (S2, an index of cytoskeletal integrity), and monomeric tubulin (S1, an index of cytoskeletal disassembly) (polyacrylamide gel electrophoresis fractionation and immunoblotting. In parental cells, oxidant caused: 1) translocation of PKC-lambda from the cytosol to the particulate (membrane + cytoskeletal) fractions, 2) activation of native PKC-lambda, 3) tubulin pool instability (increased monomeric S1 and decreased polymerized S2), 4) disruption of cytoskeletal architecture, and 5) barrier dysfunction (hyperpermeability). In transfected clones, overexpression of the atypical (74 kDa) PKC-lambda isoform by itself ( approximately 3.2-fold increase) led to oxidant-like disruptive effects, including cytoskeletal and barrier hyperpermeability. Overexpressed PKC-lambda was mostly found in particulate cell fractions (with a smaller cytosolic distribution) indicating its activation. Disruption by PKC-lambda overexpression was also potentiated by oxidant challenge. Stable inactivation of endogenous PKC-lambda ( approximately 99.6%) by a dominant-negative protected against all measures of oxidant-induced disruption. We conclude that: 1) oxidant induces disruption of epithelial barrier integrity by disassembling the cytoskeleton, in large part, through the activation of PKC-lambda isoform; and 2) activation of PKC-lambda by itself appears to be sufficient for disruption of cellular cytoskeleton and monolayer barrier permeability. The unique ability to mediate an oxidant-like injury and cytoskeletal depolymerization and instability is a novel mechanism not previously attributed to the atypical subfamily of PKC isoforms.

Concurrent emphysematous pyelonephritis and emphysematous cholecystitis in type 2 diabetes

Concurrence of emphysematous pyelonephritis and emphysematous cholecystitis in a patient with type 2 diabetes has not been reported in the published literature, to the authors' knowledge. A patient who had both at the time of presentation is reported. The mechanism of gas formation and the management strategies are discussed.

A comparison of sonourethrography and retrograde urethrography in evaluation of anterior urethral strictures

AIM

This prospective study was undertaken to evaluate the abnormalities of the male anterior urethra using high-resolution ultrasound (sonourethrography) and to compare the efficacy with that of retrograde urethrography (RGU) using operative findings as the gold standard.

MATERIALS AND METHODS

Seventy patients with symptoms of lower urinary tract obstruction underwent RGU followed by sonourethrography. The sonologist was blinded to the findings of RGU. The parameters studied were compared with the intra-operative findings as gold standard, and the sensitivity, specificity and overall accuracy for the procedures were calculated. Chi-square test and kappa statistics were used where appropriate.

RESULTS

All patients found to have urethral stricture disease by RGU were also detected by sonourethrography and confirmed intra-operatively. In the estimation of stricture length, RGU showed a lower sensitivity (60-80%) for lengths 1-4 cm, compared with sonourethrography (73.3-100%). Spongiofibrosis was detected by sonourethrography with a sensitivity of 77.3-83.3%. All the false tracts and calculi detected at sonourethrography were confirmed at surgery, whereas RGU showed a low sensitivity in their detection. The complications encountered during the procedures were pain, urethral bleeding and contrast intravasation. The frequency of pain during RGU was greater (p < 0.001); however, the difference in frequency of bleeding after the two procedures was not significant (p < 0.5).

CONCLUSION

RGU and sonourethrography are equally efficacious in detection of anterior urethral strictures. Further characterization of strictures in terms of length, diameter and periurethral pathologies, like spongiofibrosis and false tracts, is done with greater sensitivity using sonourethrography as compared with RGU, with the added benefit of lower incidence of complications.

Extracellular calcium is a potent inducer of cyclo-oxygenase-2 in murine osteoblasts through an ERK signaling pathway

[Ca2+]e may be important in bone turnover. We found [Ca2+]e induces COX-2 transcription and PGE2 production in primary calvarial osteoblasts through an ERK signaling pathway. Inhibition of PGE2 production inhibited the [Ca2+]e stimulation of osteoblastic differentiation but not the increase in cell number. Hence, some effects of [Ca2+]e on bone may be mediated by COX-2.

INTRODUCTION

Local changes in extracellular calcium ([Ca2+]e) may play an important role in bone turnover. We examined the possibility that prostaglandins produced by cyclo-oxygenase-2 (COX-2) could mediate some of the effects of [Ca2+]e on osteoblasts.

METHODS

We examined the [Ca2+]e induction of COX-2 expression and prostaglandin E2 (PGE2) production in primary osteoblasts (POBs) obtained by sequential enzymatic digestion of mouse calvariae. We measured mRNA and protein levels by Northern and Western analyses and PGE2 production in culture medium by radioimmunoassay (RIA). COX-2 promoter activity was measured as luciferase activity in calvarial osteoblasts derived from mice transgenic for 371 bp of the COX-2 promoter fused to a luciferase reporter gene.

RESULTS AND CONCLUSIONS

COX-2 mRNA and protein expression were induced by 3-40 mM of [Ca2+]e. [Ca2+]e (5 mM) induced COX-2 mRNA within 30 minutes; levels peaked at 6-9 h and remained elevated at 24 h. Cumulative medium PGE2 was increased at 3 h, with levels rising to 30 nM at 24 h. PGE2 production in POBs from mice with only COX-1 gene expression was 1/40th of that in POBs from mice with both COX-1 and COX-2 gene expression. [Ca2+]e increased alkaline phosphatase activity and osteocalcin mRNA, and this increase was blocked by inhibiting PGE2 production. [Ca2+]e stimulation of COX-2 promoter activity correlated with the induction of COX-2 mRNA expression. [Ca2+]e induced rapid and transient phosphorylation of extracellular signal-regulated kinase (ERK) in POBs, which peaked at 5-10 minutes. Inhibition of ERK phosphorylation with the specific inhibitors, PD-98059 and U-0126, decreased the [Ca2+]e induction of both COX-2 mRNA and luciferase activity by 70-80%. Although less effective than [Ca2+]e, strontium [Sr2+]e also induced COX-2 mRNA and promoter activity in POBs through an ERK signaling pathway. We conclude that [Ca2+]e is a potent transcriptional inducer of COX-2 expression and PGE2 production in osteoblasts through an ERK signaling pathway.

Energy balance of adolescent girls in rural area of Varanasi

Although several studies have been undertaken on dietary intake of adolescent girls, studies on their energy expenditure and thereby energy balance are few. In order to explore these aspects, this community based cross-sectional study was done on 270 adolescent girls of a rural area of Varanasi, selected by adopting appropriate sampling technique. Nutritional status of study subjects was assessed on the basis of BMI. Their energy intake was computed by 24 hours recall oral questionnaire method. Estimation of energy expenditure was based on physical activity which was noted by 24 hours activity recall questionnaire method. Average energy intake (1609.42 +/- 528.87 kcal/day) of the study subjects was less than their mean energy expenditure (1896.19 kcal/day). Their energy expenditure was significantly influenced by several factors (e.g. age, caste, type of family, etc.) As much as 69.63%, subjects were in negative energy balance. Majority of subjects belonging to lower (79.37%) and middle (75.19%) SES were in the negative energy balance. Negative energy balance has been significantly less in subjects belonging to high SES, having main occupation of the family as business and high per capita income groups with respect to their corresponding subcategories. In all 68.52% study subjects had BMI < 18.5 kg/m2. Majority (91.11%) of adolescent girls had rate of energy expenditure > 1.4. Under nutrition was significantly (p<0.05) more in subjects with rate of energy expenditure > 1.4 (i.e. 70.33%) than in subjects with rate of energy expenditure < or = 1.4.

Possible involvement of oxidative stress in cisplatin-induced apoptosis in LLC-PK1 cells

Use of cisplatin, a chemotherapeutic agent, is associated with toxicity as a significant number of patients develop a decline in renal function. The mechanisms by which cisplatin produces renal injury are not well understood. It has been suggested that free radical-catalyzed lipid peroxidation can induce apoptosis or necrosis leading to renal injury. This study examined whether low concentrations of cisplatin induce apoptosis in LLC-PK1 cells and whether caspases 1, 2, 3, 8, and 9 are activated during this event. Our results show a dose- and time-dependent induction of apoptosis by micromolar concentrations of cisplatin. Expression of oncogenes c-myc and p53 was induced, and except for caspase 1, all the other caspases tested were activated. Z-VAD, the broad-spectrum inhibitor of caspases, prevented caspase activation and apoptosis, but not c-myc and p53 induction. On the other hand, N-acetylcysteine prevented cisplatin-induced apoptosis as well as c-myc induction but not p53 induction. The antioxidant trolox also prevented cisplatin-induced apoptosis. The results suggest that antioxidants and caspase inhibitors may alleviate cisplatin-associated nephrotoxicity.

Fluid flow induces COX-2 expression in MC3T3-E1 osteoblasts via a PKA signaling pathway

Mechanical loading of bone generates fluid flow within the mineralized matrix which can exert fluid shear stress (FSS) at cell membranes. FSS induces new transcription of cyclooxygenase-2 (COX-2) in MC3T3-E1 osteoblasts, with peak effects at 4-5h. Using MC3T3-E1 cells stably transfected with the COX-2 promoter fused to a luciferase reporter, we examined involvement of the protein kinase A (PKA) and protein kinase C (PKC) signaling pathways in the peak COX-2 mRNA and luciferase responses to FSS (10dyn/cm(2)). Neither inhibition nor down-regulation of the PKC pathway affected the FSS stimulation of COX-2 mRNA or luciferase activity. In contrast, inhibitors of the PKA pathway, used at doses which inhibited forskolin-stimulated luciferase activity by 70-80%, reduced FSS-stimulated COX-2 mRNA expression and luciferase activity by 50-80%. Hence, peak FSS induction of COX-2 expression in MC3T3-E1 osteoblastic cells is largely dependent on the PKA signaling pathway.

Cellular lipid peroxidation end-products induce apoptosis in human lens epithelial cells

Hydrogen peroxide (H(2)O(2)), an oxidant present in high concentrations in the aqueous humor of the elderly eyes, is known to impart toxicity to the lens---apoptosis being one of the toxic events. Since H(2)O(2) causes lipid peroxidation leading to the formation of reactive end-products, it is important to investigate whether the end-products of lipid peroxidation are involved in the oxidation-induced apoptosis in the lens. 4-Hydroxynonenal (HNE), a major cytotoxic end product of lipid peroxidation, has been shown to mediate oxidative stress-induced cell death in many cell types. It has been shown that HNE is cataractogenic in micromolar concentrations in vitro, however, the underlying mechanism is not yet clearly understood. In the present study we have demonstrated that H(2)O(2) and the lipid derived aldehydes, HNE and 4-hydroxyhexenal (HHE), can induce dose- and time-dependent loss of cell viability and a simultaneous increase in apoptosis involving activation of caspases such as caspase-1, -2, -3, and -8 in the cultured human lens epithelial cells. Interestingly, we observed that Z-VAD, a broad range inhibitor of caspases, conferred protection against H(2)O(2)- and HNE-induced apoptosis, suggesting the involvement of caspases in this apoptotic system. Using the cationic dye JC-1, early apoptotic changes were assessed following 5 h of HNE and H(2)O(2) insult. Though HNE exposure resulted in approximately 50% cells to undergo early apoptotic changes, no such changes were observed in H(2)O(2) treated cells during this period. Furthermore, apoptosis, as determined by quantifying the DNA fragmentation, was apparent at a much earlier time period by HNE as opposed to H(2)O(2). Taken together, the results demonstrate the apoptotic potential of the lipid peroxidation end-products and suggest that H(2)O(2)-induced apoptosis may be mediated by these end-products in the lens epithelium.

Preventing gut leakiness by oats supplementation ameliorates alcohol-induced liver damage in rats

Only 30% of alcoholics develop liver disease (ALD) suggesting that additional factors are needed. Endotoxin is one such factor, but its etiology is unclear. Since the gut is the main source of endotoxin, we sought to determine whether an increase in intestinal permeability (leaky gut) is required for alcohol-induced endotoxemia and liver injury and whether the gut leakiness is preventable. For 10 weeks, rats received by gavage increasing alcohol doses (to 8 g/kg/day) and either oats (10 g/kg) or chow b.i.d. Intestinal permeability was then assessed by urinary excretion of lactulose and mannitol. Liver injury was evaluated histologically, biochemically (liver fat content), and by serum aminotransferase. Alcohol caused gut leakiness that was associated with both endotoxemia and liver injury. Oats prevented these changes. We conclude that chronic gavage of alcohol in rats is a simple experimental model that mimics key aspects of ALD, including endotoxemia and liver injury, and can be useful to study possible mechanisms of endotoxemia in ALD. Since preventing the gut leakiness by oats also prevented the endotoxemia and ameliorated liver damage in rat, our results suggest that alcohol-induced gut leakiness 1) may cause alcohol-induced endotoxemia and liver injury and 2) may be the critical cofactor in the 30% of alcoholics who develop ALD. Further studies are needed to determine whether ALD in humans can be prevented by preventing alcohol-induced gut leakiness, studies that should lead to the development of useful therapeutic agents for the prevention of ALD.

Protective effect of nimodipine on dichlorvos-induced delayed neurotoxicity in rat brain(1)

The effect of dichlorvos (200 mg/kg body weight) with or without nimodipine (6 mg/kg body weight/day for 3 days, starting 1 day prior to the administration of dichlorvos) on calcium homeostasis was studied in the rat brain. The delayed neurotoxic potential of dichlorvos was assessed in terms of neuropathy target esterase (NTE) inhibition in the brain and the subsequent development of motor incoordination at 21 days post-exposure. NTE activity had recovered up to 84% at the time of clinical manifestations. No signs of motor deficit were present when nimodipine was given with dichlorvos. The administration of dichlorvos alone caused an increase in intrasynaptosomal Ca(2+) with a concomitant increase in calpain activity. These increases in calpain activity and in the levels of intracellular Ca(2+) were not observed when nimodipine was administered to rats treated with dichlorvos. Also, the inhibition of calcium ATPase following the exposure to dichlorvos was reduced when animals received nimodipine. This indicates that nimodipine, a centrally acting calcium channel blocker, may contribute to the amelioration of dichlorvos-induced neurotoxicity by attenuation of calcium-mediated disruption of cytoskeletal homeostasis, without preventing NTE inhibition.

Modulation of glyoxalase, glutathione S-transferase and antioxidant enzymes in the liver, spleen and erythrocytes of mice by dietary administration of fenugreek seeds

There is a growing interest in understanding the biological effect of time-tested folk medicinal plants. In the present work, the effect of dietary administration of fenugreek seeds on the glyoxalase system and antioxidant enzymes as well as levels of glutathione (GSH) have been examined in different tissues of mice. Swiss albino mice were fed with diet containing powdered fenugreek for 4 weeks. The mode and magnitude of effect was found to depend on the dose of fenugreek and type of tissue. The diet containing 1 and 2% of fenugreek enhanced the specific activity of gly I, whereas 5 and 10% inhibited its activity in the liver. However, on the other hand, the specific activity of gly II decreased continuously with dose. Dietary administration of fenugreek seeds resulted in an increase of GSH levels and the glutathione S-transferase (GST) activity in the liver. Fenugreek (1 and 2%) showed no appreciable change in superoxide dismutase (SOD) and catalase. However, 5 and 10% doses of fenugreek supplementation inhibited their activities. In the case of spleen, a significant change in gly I was observed only at 10% fenugreek. In addition, a significant increase was also observed with GSH levels. Fenugreek treatment up to 5% showed a small but consistent increase in erythrocytes. In the case of GST, the activity enhanced with dose. Significant elevation of catalase activity was observed with a 10% dose of fenugreek. The significance and relevance of these findings are suggested in relation to mechanistic aspects.

Novel antioxidants zolimid and AEOL11201 ameliorate colitis in rats

The mechanism of tissue damage in ulcerative colitis (UC) is unknown. However, recent evidence suggests that reactive oxygen species (ROS) are critical mediators of inflammation, and tissue damage in UC and antioxidants could be beneficial in the treatment of UC. Our aim was to evaluate the effects of two new antioxidants, Zolimid and AEOL11201 on experimental colitis. Antioxidants or vehicle were given to rats for five days after induction of colitis by intrarectal administration of 4% acetic acid. Severity of colitis was assessed on day 5. Zolimid and AEOL11201 significantly improved acetic acid-induced colitis. Both Zolimid and AEOL11201 significantly decreased the severity of diarrhea, and severity of macroscopic and histological changes in the colon. Both agents also significantly decreased colonic MPO levels. In conclusion, Zolimid and AEOL11201 are effective antiinflammatory agents in an animal model of colitis. Further studies are needed to evaluate their beneficial therapeutic effects in patients with UC.

Interferon action against human parainfluenza virus type 3: involvement of a novel antiviral pathway in the inhibition of transcription

Interferon (IFN)-induced 2'-5' oligoadenylate synthetase (2-5A synthetase)/RNase L, PKR, and Mx proteins are considered to be the principal antiviral protein pathways through which IFN induces an antiviral state. It was previously reported that human parainfluenza virus type 3 (HPIV3) multiplication was inhibited by IFN-alpha in human lung epithelial cells A549 and that MxA was found to contribute to the inhibition process (Zhao et al., Virology 220:330-338, 1996). Viral primary transcription was dramatically inhibited in A549 cells after IFN-alpha treatment, but a step following primary transcription was inhibited in U87-MxA cells constitutively expressing MxA. Here we have investigated the role of MxA, believed to be cell type specific, and other antiviral pathways in the inhibition of viral primary transcription. Our data indicate that a novel IFN-induced pathway(s) is involved in the inhibition of primary transcription. This is based on the following findings: (i) IFN-alpha inhibited viral primary transcription in U87-MxA and other cell types including cells lacking MxA; (ii) cells constitutively expressing 2-5A synthetase had no antiviral effect against HPIV3; and (iii) primary transcription occurred in the absence of protein synthesis, a step of PKR target. The novel antiviral pathway(s) was induced by both IFN-alpha and IFN-gamma to establish an effective antiviral state against HPIV3. By using IFN-alpha-signaling mutant cells, we found that IFN-gamma could elicit antiviral effect against HPIV3 without cross talk with the IFN-alpha-signaling pathway. These data provide the first evidence that a novel antiviral pathway(s) contributes to the antiviral action of IFN against a nonsegmented negative-strand RNA virus by targeting the primary transcription.

Possible role of enhanced microtubule phosphorylation in dichlorvos induced delayed neurotoxicity in rat

The effect of a single subcutaneous dose of 200 mg/kg body weight dichlorvos on neuronal microtubule phosphorylation has been studied in rat following the development of organophosphate induced delayed neurotoxicity (OPIDN). Microtubule associated Ca2+/calmodulin dependent as well as cAMP dependent protein kinases were assayed. Dichlorvos administration led to a consistent increase in the activity of both the kinases at all post exposure intervals (7th, 15th and 21st day) as compared to that of controls. After in vitro phosphorylation using [gamma-32P]ATP, various proteins were resolved on one-dimensional 8% SDS-PAGE, stained with Coomassie Blue and autoradiographed. The amount of 32P incorporated was quantified by microdensitometry. Dichlorvos enhanced the phosphorylation of 55- and 280-kDa proteins. These two proteins were identified as tubulin and microtubule associated protein-2 (MAP-2) by immunoblotting. This study showed that dichlorvos induced hyperphosphorylation of tubulin and MAP-2 which in turn destabilizes microtubule assembly, and may ultimately result in axonal degeneration leading to dichlorvos induced delayed neurotoxicity.

Successful and sustained treatment of chronic radiation proctitis with antioxidant vitamins E and C

OBJECTIVE

Chronic radiation proctitis, a common sequelae of pelvic radiation, is characterized by obliteration of the submucosal vasculature with subsequent ischemia and reperfusion injury. Oxidative stress is thought to be a major mechanism in radiation proctitis. Therefore, antioxidants (vitamins E and C) may be beneficial.

METHODS

Twenty consecutive symptomatic outpatients with endoscopically documented radiation proctitis seen in a single gastroenterology clinic were given a combination of vitamin E (400 IU tid) and vitamin C (500 mg tid). Previous radiation therapy was given for prostatic (n = 10) or gynecological (n = 10) malignancies. These patients presented with one or more of the following symptoms: rectal bleeding, rectal pain, diarrhea, or fecal urgency. Using a questionnaire, these symptoms were rated by the patients in terms of their severity (grade 0-4) and frequency (grade 0-4) before and after treatment with vitamins E and C. A symptom index was calculated by the addition of the severity and frequency scores (8 = most symptomatic). The lifestyle impact of the symptoms was also assessed by questionnaire grading from 0 (no effect on daily activity) to 4 (afraid to leave home). Among these 20 patients, 10 patients who received vitamins E and C for 1 yr were assessed again to determine whether their initial responses were sustained.

RESULTS

There was a significant (p < 0.05; Wilcoxon rank) improvement in the symptom index (before treatment vs after treatment with vitamins E and C) for bleeding (median score: 4 vs 0), diarrhea (median score: 5 vs 0), and urgency (median score: 6 vs 3). Patients with rectal pain did not improve significantly. Bleeding resolved in four of 11 patients, diarrhea resolved in eight of 16 patients, fecal urgency resolved in three of 16 patients, and rectal pain resolved in two of six patients. Lifestyle improved in 13 patients, including seven patients who reported a return to normal. Two of the patients with no improvement in their daily symptoms also had radiation ileitis. All 10 patients who underwent a second follow-up interview reported sustained improvement in their symptoms 1 yr later.

CONCLUSION

A substantial number of patients with radiation proctitis seem to benefit from antioxidant therapy. A double-blind placebo-controlled trial is needed to confirm this open-labeled pilot study.

Chloroform-soluble schiff-base Zn(II) or Cd(II) complexes from a dynamic combinatorial library

A dynamic combinatorial library of metal ion Schiff-base complexes have been studied for the extraction of Zn(II) or Cd(II) from aqueous solution into chloroform. Library components consist of different aminophenols and 2-pyridinecarboxaldehyde. Extraction of both Zn(II) and Cd(II) into chloroform was observed from aqueous solutions containing 0.0500 mM M(NO3)2, 0.100 M aminophenol, 0.100 M 2-pyridinecarboxaldehyde, 0.100 M NaCl, and 5.00 mM buffer at pH 8.5. Extraction was dependent on pH but not on counterions including Cl-, Br-, or NO3-. Studies showed that equilibrium was attained between the Schiff-base complexes across the two-phase chloroform-water system after 24 h of stirring. Analysis of the extracted species by use of 1H NMR spectroscopy and mass spectrometry as well as solubility studies on characterized complexes suggested that the major extracted species is the neutral bis-Schiff-base metal ion complex. In libraries containing mixtures of two different aminophenols and 2-pyridinecarboxaldehyde, an enhanced extent of extraction of Zn(II) into chloroform is observed. Studies suggest that a Zn(II) complex, which is likely the mixed Schiff-base complex, has superior extraction properties compared to simple libraries with a single aminophenol component. The structures of two bis-Schiff-base complexes of Zn(II) and one of Cd(II) have been determined by X-ray crystallography. The geometries of the two Zn(II) complexes, which differ only by a methyl substituent on the Schiff-base ligand, are markedly different, supporting the use of combinatorial methods in coordination chemistry. Zn(SB14)2 crystallized as the sesquihydrate (C24H18N4O2Zn.1.5 H2O) in the space group C2/c, with cell dimensions a = 23.219(15) A, b = 11.299(7) A, c = 16.822(11) A, beta = 102.91(5) degrees, V = 4302(5) A3, and Z = 8. Zn(SB15)2 crystallized as a 1:1 methanol solvate (C26H22N4O2Zn.CH3OH) in the space group P2(1)/c with cell dimensions a = 13.981(5) A, b = 7.978(3) A, c = 22.568(8) A, beta = 104.53(3) degrees, V = 2436.8(15) A3, and Z = 4. Cd(SB14)2 crystallized as a 1:1 ethanol solvate (C24H18N4O2Cd.CH3CH2OH) in the space group R3 with unit cell dimensions of a = 36.423(2) A, c = 9.2930(10) A, V = 10678(2) A3, and Z = 18.

Delusional parasitosis: a clinical profile

OBJECTIVE

Delusional parasitosis is a form of monohypochondriacal psychosis, a condition sometimes encountered in psychiatric or primary care practice. The outcome of this condition is not well known.

METHOD

In the present study, a series of fifty-two consecutive cases of delusional parasitosis is reported.

RESULTS

A majority of cases (92%) had insidious onset. The duration of symptoms in all but two cases was six months or more. Twenty-six cases presented with a delusion of infestation by insects over the body and twenty-three cases with a delusion of insects crawling over the scalp. Three cases had associated diabetes mellitus, five cases had leprosy, five cases dementia, four cases had depression, and three cases presented with trichotillomania. Pimozide was used in forty-six cases, amitriptyline and fluoxetine in three cases each. Twenty-eight cases (54%) showed complete remission while receiving pharmacotherapy, eighteen cases showed partial improvement, and six cases did not respond to treatment.

CONCLUSION

Further studies are warranted to study the treatment and outcome of this important psychiatric disorder.

Human parainfluenza virus type 3 inhibits gamma interferon-induced major histocompatibility complex class II expression directly and by inducing alpha/beta interferon

Human parainfluenza virus type 3 (HPIV3) is one of the major causes of bronchiolitis, pneumonia, and croup in newborns and infants. Cellular immunity involving major histocompatibility complex (MHC) class I and class II molecules plays an important role in controlling virus infection. Several viruses have been shown to down-regulate gamma interferon (IFN-gamma)-mediated MHC class II expression. In this communication, we show that HPIV3 strongly inhibits the IFN-gamma-induced MHC class II expression in HT1080 human fibrosarcoma cells. The culture supernatant of HPIV3-infected cells also inhibited IFN-gamma-induced MHC class II expression, a phenomenon that was found to be due, in large part, to alpha/beta interferon (IFN-alpha/beta). Expression of MHC class I and intercellular adhesion molecule 1 occurred efficiently in cells simultaneously infected with HPIV3 and treated with IFN-gamma, indicating that the inhibitory effect of HPIV3 was specific to MHC class II. STAT1 activation was not affected by HPIV3 at early postinfection times but was partially inhibited at later times. These data suggested that the potent inhibition of MHC class II expression was, in major part, due to a defect downstream of STAT1 activation in the IFN-gamma-induced MHC class II expression pathway. Class II transactivator (CIITA) is the unique mediator of IFN-gamma-induced transcription from the MHC class II promoter. By RNase protection analysis, CIITA expression was found to be strongly inhibited in HPIV3-infected cells. The culture supernatant containing IFN-alpha/beta, on the other hand, inhibited MHC class II expression without affecting STAT1 and CIITA expression. These data indicate that HPIV3 inhibits IFN-gamma-induced MHC class II expression primarily by the viral gene products targeting CIITA and additionally by inducing IFN-alpha/beta to target one or more steps further downstream.

Exacerbation of alcoholic liver injury by enteral endotoxin in rats

Increased gut permeability (leaky gut) and endotoxin-mediated Kupffer cell activation are proposed as the mechanisms of alcoholic liver injury. Although ethanol feeding is shown to sensitize the liver for injury induced by parental administration of lipopolysaccharide (LPS), how enteral LPS loading affects alcoholic liver injury is yet to be tested. The present study provides direct evidence for enhanced entrance to portal circulation of LPS enterally administered to the intragastric ethanol infusion model. Portal and systemic blood endotoxin levels increased to 43.0 +/- 4.1 and 6.2 +/- 4.3 pg/mL at 2 hours following enteral LPS administration (5 mg/kg) in alcohol-fed animals, while no such increases were observed in pair-fed controls. However, endotoxin levels in systemic blood of alcohol-fed rats were reduced to 0 to 1. 5 pg/mL 16 hours after LPS administration. Weekly enteral administration of LPS to the model for 9 weeks exacerbated an increase in plasma alanine transaminase (ALT) levels (227 +/- 75 vs. 140 +/- 70; P <.01), mononuclear infiltration (25 +/- 22 vs. 6.4 +/- 4.4/10 mm(2); P =.02), sinusoidal congestion, and spotty necrosis, and induced diffuse coagulative necrosis and centrilobular fibrosis in some animals. Reverse-transcription polymerase chain reaction (RT-PCR) analysis confirmed the LPS effect at the tissue level by demonstrating accentuated induction of tumor necrosis factor alpha (TNF-alpha) and Cox-2 mRNA. In conclusion, enteral LPS administration potentiates alcoholic liver necrosis, inflammation, and fibrosis despite efficient endotoxin clearance by the liver and mild systemic endotoxemia that occurs episodically following enteral LPS challenge.

Role of NH(2)- and COOH-terminal domains of the P protein of human parainfluenza virus type 3 in transcription and replication

The phosphoproteins (P proteins) of paramyxoviruses play a central role in transcription and replication of the viruses by forming the RNA polymerase complex L-P and encapsidation complex (N-P) with nucleocapsid protein (N) and binding to N protein-encapsidated genome RNA template (N-RNA template). We have analyzed the human parainfluenza virus type 3 (HPIV3) P protein and deletion mutants thereof in an in vitro transcription and in vivo replication system. The in vitro system utilizes purified N-RNA template and cell extract containing L and P proteins coexpressed via plasmids using a recombinant vaccinia virus expression system. The in vivo system takes advantage of minigenome replication, which measures luciferase reporter gene expression from HPIV3 minigenomes by viral proteins in a recombinant vaccinia virus expression system. These studies revealed that the C-terminal 20-amino-acid region of P is absolutely required for transcription in vitro and luciferase expression in vivo, suggesting its critical role in viral RNA synthesis. The N-terminal 40-amino-acid region, on the other hand, is essential for luciferase expression but dispensable for transcription in vitro. Consistent with these findings, the C-terminal domain is required for binding of P protein to the N-RNA template involved in both transcription and replication, whereas the N-terminal domain is required for the formation of soluble N-P complex involved in encapsidation of nascent RNA chains during replication. Coimmunoprecipitation analysis showed that the P protein forms a stable homooligomer (perhaps a trimer) that is present in L-P and N-P complexes in the higher oligomeric forms (at least a pentamer). Interestingly, coexpression of a large excess of N- or C-terminally deleted P with wild-type P had no effect on minigenome replication in vivo, notwithstanding the formation of heterooligomeric complexes. These data indicate that P protein with a deleted terminal domain can function normally within the P heterooligomeric complex to carry out transcription and replication in vivo.

Neurologic complications of dropsy: from possibility to reality

Epidemic dropsy, which results from the accidental ingestion of mustard oil adulterated with argemone oil, has been associated with certain neurologic symptoms. The occurrence of objective neurologic involvement has, however, precluded this illness. We report two cases, who were victims of epidemic dropsy in the recent outbreak in India and showed objective neurologic deficit in the form of brachial neuritis.

Local tissue reactions to oil-based breast implant bleed

We present two cases (three implants) of symptomatic local tissue reactions to Trilucent breast implant bleeds. The implant shells had changed their colour and texture. Capsule histology showed foreign body reaction and inflammatory changes. These findings question the safety of these implants.

Specific phosphorylated forms of glyceraldehyde 3-phosphate dehydrogenase associate with human parainfluenza virus type 3 and inhibit viral transcription in vitro

We previously reported specific interaction of cellular glyceraldehyde 3-phosphate dehydrogenase (GAPDH), the key glycolytic enzyme, and La protein, the RNA polymerase III transcription factor, with the cis-acting RNAs of human parainfluenza virus type 3 (HPIV3) and packaging of these proteins within purified virions (B. P. De, S. Gupta, H. Zhao, J. Z. Drazba, and A. K. Banerjee, J. Biol. Chem. 271:24728-24735, 1996). To gain further insight into these molecular interactions, we analyzed the virion-associated GAPDH and La protein using two-dimensional gel electrophoresis and immunoblotting. The GAPDH was resolved into two major and one minor molecular species migrating in the pI range of 7.6 to 8.3, while the La protein was resolved into five molecular species in the pI range of 6.8 to 7.5. The GAPDH isoforms present in the virions were also detected in the cytoplasmic fraction of CV-1 cell extract, albeit as minor species. On the other hand, the multiple molecular forms of La protein as seen within the virions were readily detected in the total CV-1 cell extract. Further analysis of virion-associated GAPDH by in vivo labeling with [(32)P]orthophosphate revealed the presence of multiple phosphorylated species. The phosphorylated species were able to bind specifically to the viral cis-acting 3' genome sense RNA but failed to bind to the leader sense RNA, as determined by gel mobility shift assay. In contrast, the La protein isoforms present within the virions were not phosphorylated and bound to the viral cis-acting RNAs in a phosphorylation-independent manner. The GAPDH isoforms purified from the CV-1 cell cytoplasmic fraction inhibited viral transcription in vitro. Consistent with this, flag-tagged recombinant GAPDH synthesized by using the vaccinia virus expression system also inhibited viral transcription. Together, these data indicate that specific phosphorylated forms of GAPDH associate with HPIV3 and are involved in the regulation of virus gene expression.

Oxidant-induced intestinal barrier disruption and its prevention by growth factors in a human colonic cell line: role of the microtubule cytoskeleton

Reactive oxygen metabolites (ROM) are increased in the inflamed mucosa of inflammatory bowel disease (IBD) and may contribute to loss of intestinal barrier function in this disorder. Growth factors (GF) are protective. But the mechanisms of disruption and protection remain elusive. In the present investigation, we hypothesized that the microtubules (a critical cytoskeletal element) play a key role in the molecular mechanism of intestinal barrier dysfunction induced by ROM and in GF-mediated protection. Utilizing monolayers of a human colonic cell line (Caco-2), we evaluated the effects of ROM (H(2)O(2) or HOCl), in the presence or absence of GF (epidermal growth factor [EGF]; transforming growth factor-alpha [TGF-alpha]), on intestinal barrier function, tubulin (microtubule structural protein), and microtubule stability. Monolayers were also processed for two highly sensitive western immunoblots: fractionated polymerized tubulin (S2; an index of stability); monomeric tubulin (S1; an index of disruption) to detect the oxidation and disassembly/assembly of tubulin. ROM exposure led to a significant increase in the oxidation of tubulin, decrease in the stable S2 polymerized tubulin, and increase in the unstable S1 monomeric tubulin. In concert, each ROM in a dose dependent manner damaged the microtubule cytoskeleton and disrupted barrier function. GF pretreatment not only increased the S2 stable tubulin and decreased tubulin oxidation but also, concomitantly, prevented the disruption of microtubules and loss of barrier function in monolayers exposed to ROM. Antibody against the GF-receptor and inhibitors of GF-receptor tyrosine kinase abolished GF protection, indicating the involvement of epidermal growth factor receptor (EGFR) signaling pathway. As predicted, colchicine, an inhibitor of microtubule assembly, caused barrier dysfunction and prevented GF protection whereas taxol, a microtubule-stabilizing agent, mimicked the protective effects of GF. Thus, organization and stability of the microtubule cytoskeleton appears to be critical to both oxidant-induced mucosal barrier dysfunction and protection of intestinal barrier mediated by GF. Therefore, microtubules may be useful targets for development of drugs for the treatment of IBD.

The phosphoprotein of rabies virus is phosphorylated by a unique cellular protein kinase and specific isomers of protein kinase C

The phosphoprotein (P) gene of rabies virus (CVS strain) was cloned and expressed in bacteria. The purified protein was used as the substrate for phosphorylation by the protein kinase(s) present in cell extract prepared from rat brain. Two distinct types of protein kinases, staurosporin sensitive and heparin sensitive, were found to phosphorylate the P protein in vitro by the cell extract. Interestingly, the heparin-sensitive kinase was not the ubiquitous casein kinase II present in a variety of cell types. Further purification of the cell fractions revealed that the protein kinase C (PKC) isomers constitute the staurosporin-sensitive kinases alpha, beta, gamma, and zeta, with the PKCgamma isomer being the most effective in phosphorylating the P protein. A unique heparin-sensitive kinase was characterized as a 71-kDa protein with biochemical properties not demonstrated by any known protein kinases stored in the protein data bank. This protein kinase, designated RVPK (rabies virus protein kinase), phosphorylates P protein (36 kDa) and alters its mobility in gel to migrate at 40 kDa. In contrast, the PKC isoforms do not change the mobility of unphosphorylated P protein. RVPK appears to be packaged in the purified virions, to display biochemical characteristics similar to those of the cell-purified RVPK, and to similarly alter the mobility of endogenous P protein upon phosphorylation. By site-directed mutagenesis, the sites of phosphorylation of RVPK were mapped at S(63) and S(64), whereas PKC isomers phosphorylated at S(162), S(210), and S(271). Involvement of a unique protein kinase in phosphorylating rabies virus P protein indicates its important role in the structure and function of the protein and consequently in the life cycle of the virus.

Angiographic patterns of in-stent restenosis and implications on subsequent revascularization

Stent implantation has become the mainstay of percutaneous revascularization for most coronary lesions; in-stent restenosis (ISR) can occur in 6%-40% of stent procedures and the subsequent response to repeat intervention can possibly be predicted by the angiographic patterns of ISR. This study evaluated the incidence and predictors of angiographic patterns of ISR and its impact on subsequent target lesion revascularization (TLR) in 100 consecutive patients having Palmaz-Schatz ISR undergoing intervention. Diffuse ISR (>/=10 mm) was observed in 78% and focal ISR (>10 mm) in 22%. Diffuse vs. focal ISR occurred earlier after stent implantation and was more common in diabetics. Angiographic predictors of diffuse ISR were stent implantation for a restenotic lesion, long lesions, smaller vessel, stenting without debulking, and high-pressure balloon inflation (>16 atm). TLR after repeat intervention was 46% for diffuse and 14% for focal ISR (P < 0.02). Rotational atherectomy resulted in lower TLR (31%) vs. PTCA or restent (64%) in diffuse ISR (P < 0.004). Therefore, diffuse ISR is more common than focal ISR, usually occurs in the setting of aggressive intimal hyperplasia, and can be predicted by clinical and angiographic variables. Also, diffuse intimal hyperplasia within a stent responds poorly to PTCA and may benefit from a more aggressive debulking strategy such as rotational atherectomy. Cathet. Cardiovasc. Intervent. 49:23-29, 2000.

Ethanol-induced barrier dysfunction and its prevention by growth factors in human intestinal monolayers: evidence for oxidative and cytoskeletal mechanisms

Exposure of intestinal mucosa to ethanol (EtOH) disrupts barrier function and growth factors [epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha)] are protective, but the mechanisms remain obscure. Accordingly, we sought to determine whether the molecular mechanism of EtOH-induced intestinal barrier dysfunction involves oxidative stress and disassembly of microtubules and whether the mechanism of protection by EGF or TGF-alpha involves prevention of these alterations. To this end, human colonic (Caco-2) monolayers were exposed to 0 to 15% EtOH with or without pretreatment with EGF or TGF-alpha (10 ng/ml) or with oxidative or cytoskeletal modulators. Effects on cell viability, barrier function, tubulin (microtubules), and oxidative stress were then determined. Cells were also processed for immunoblots of polymerized tubulin (S2; index of stability) and the monomeric tubulin (S1; index of disruption). EtOH dose-dependently decreased the stable S2 polymerized tubulin and concomitantly increased measures of oxidative stress, including oxidation and nitration of tubulin, fluorescence of dichlorofluorescein, and inducible nitric oxide synthase activity. EtOH also dose-dependently disrupted barrier function and extensively damaged microtubules, and these effects were prevented by pretreatment with antioxidant scavengers: L-cysteine, superoxide dismutase, and L-N(6)-1-iminoethyl-lysine (an inducible nitric oxide synthase inhibitor). In monolayers exposed to EtOH, pretreatment with EGF or TGF-alpha prevented the oxidation and nitration of tubulin, increases in the levels of the unstable S1 tubulin, disruption of microtubules, and barrier dysfunction. A microtubule stabilizer (paclitaxel,Taxol) mimicked, in part, the effects of EGF and TGF-alpha, whereas a microtubule disruptive drug (colchicine) prevented the protective effects of these growth factors. We concluded that mucosal barrier dysfunction induced by EtOH involves oxidative stress, which causes the disassembly of the microtubule cytoskeleton. Protection by EGF and TGF-alpha involves the prevention of these EtOH-induced alterations in microtubules.

Ambulatory 24-hour electrocardiographic monitoring following total cavopulmonary connection

A total of 72 patients (53 males, 19 females) in the age range 1-22 years (mean 6.4 years) who underwent univentricular repair between April 1990 and May 1997 at our institute were followed up from six months to seven years (mean 3.6 years). Twenty-four hours ambulatory electrocardiographic Holter monitoring was done in all the patients. Thirty-four out of 40 patients (85%) who underwent fenestrated total cavopulmonary connection and 25 out of 32 patients (78%) who underwent non-fenestrated total cavopulmonary connection had normal Holter recording; thus 59 out of 72 (82%) patients had normal findings. Among the fenestrated total cavopulmonary connections, three patients each had atrial tachycardia and sinus bradycardia. In the non-fenestrated group, two patients had atrial tachycardia, three had supraventricular tachycardia, one sinus bradycardia and one had intermittent ventricular tachycardia. No correlation was found between age at surgery, pre-operative morphology, cross clamp time or cardiopulmonary bypass time with post-operative arrhythmia. To conclude, post-operative arrhythmias following total cavopulmonary connection were not related to age at surgery, pre-operative morphology, cross clamp or cardiopulmonary bypass time. However, a larger patient pool and longer follow-up is required for evaluation of any definitive correlation.