Effect of hereditary obesity on renal expressions of NO synthase, caveolin-1, AKt, guanylate cyclase, and calmodulin

BACKGROUND

Obesity has emerged as a major cause of diabetes, cardiovascular disease, and renal insufficiency worldwide. Obese Zucker rats exhibit hyperphagia, obesity, insulin resistance, hyperlipidemia, and glomerulosclerosis and are frequently used as a model to study hereditary form of metabolic syndrome. Nitric oxide plays a major role in preservation of renal function and structure. The present study was designed to test the hypothesis that renal disease in this model may be associated with down-regulation of endothelial (eNOS) and neuromal NO synthases (nNOS) in the kidney. The study further sought to explore expressions of caveolin-1, phospho AKt, and calmodulin, which regulate activities of constituitive NOS isoforms, as well as soluble guanylate cyclase (sGC), which is involved in NO signaling.

METHODS

Twenty-two-week-old male obese and lean Zucker rats were studied. Body weight, serum lipids, urine albumin excretion, and renal tissue abundance of the above proteins were determined.

RESULTS

Serum glucose and arterial pressure were unchanged, whereas urinary NO metabolite (NO(chi)) excretion and renal tissue nitrotyrosine abundance were markedly reduced (denoting depressed NO production) in the obese versus lean Zucker rats. This was accompanied by significant glomerulosclerosis, tubulointerstitial damage, renal immune cell infiltration, marked down-regulations of renal tissue eNOS and nNOS, mild reduction of caveolin-1, and unchanged calmodulin, phospho-AKt, and sGC.

CONCLUSION

Hereditary obesity can result in down-regulations of kidney eNOS and nNOS, marked reduction of NO production, and glomerulosclerosis prior to the onset of frank diabetes and hypertension.

Expression of NOX-I, gp91phox, p47phox and P67phox in the aorta segments above and below coarctation

Aorta coarctation results in hypertension (HTN) in the arterial tree proximal to stenosis and, as such, provides an ideal model to discern the effects of different levels of blood pressure on the vascular tissue in the same animal. Compelling evidence has emerged supporting the role of oxidative stress as a cause of HTN. However, whether or not HTN (independent of the circulating humoral factors) can cause oxidative stress is less certain. NAD(P)H oxidase isoforms are the main source of reactive oxygen species (ROS) in the vascular tissues. We therefore compared the expressions of NOX-I, gp91phox and the regulatory subunits of the enzyme in the aorta segments residing above and below coarctation in rats with abdominal aorta banding. Rats were studied 4 weeks after aorta banding above the renal arteries or sham operation. Subunits of NAD(P)H oxidase and its NOX-I isoform as well as endothelial NO synthase (eNOS) and nitrotyrosine (footprint of NO oxidation by superoxide) were measured in the aorta segments above and below coarctation. The gp91phox, p47phox, and p67phox subunits of NAD(P)H oxidase, NOX-I isoform, eNOS and nitrotyrosine were markedly increased in the aorta segment above coarctation (hypertensive zone), but were virtually unchanged in the segment below coarctation. Since, excepting blood pressure, all other conditions were constant, the upregulation of NAD(P)H oxidase isoforms and the increased NO oxidation in the aorta segment above, but not below, coarctation prove that HTN, per se, independent of circulating mediators can cause oxidative/nitrosative stress in the arterial wall. These observations suggest that HTN control may represent a specific form of antioxidant therapy for hypertensive disorders.

Bradykinin Down-Regulates, Whereas Arginine Analogs Up-Regulates, Endothelial Nitric-Oxide Synthase Expression in Coronary Endothelial Cells

Bradykinin (BK) is an endogenous vasoactive peptide that promotes vasodilation by stimulating the release of nitric oxide (NO) from endothelial cells via activation of endothelial NO synthase (eNOS). Although the role of BK in modulation of eNOS activity is well understood, its possible effect on eNOS expression remains uncertain. Several studies have demonstrated negative feedback regulation of eNOS by NO. Therefore, we hypothesized that sustained stimulation with BK may down-regulate eNOS expression in endothelial cells. Human coronary endothelial cells were incubated for 24 h with either BK alone or BK plus BK receptor type 1 or type 2 blockers. NO production and eNOS abundance (Western analysis) were determined. In separate experiments, cells were incubated with either an NOS inhibitor alone or in combination with BK. Incubation with BK caused a concentration-dependent rise in NO production and a dose-dependent decline in eNOS protein expression. These effects were abrogated by BK-2 blockade but unaffected by BK-1 blockade. In contrast, NOS inhibitors lowered NO production and raised eNOS abundance in a dose-dependent fashion. The effects of BK on NO production and eNOS expression were abrogated by the NOS inhibitor. Thus, sustained activation of eNOS by BK results in a compensatory down-regulation of eNOS, whereas its sustained inhibition leads to a compensatory up-regulation of eNOS. The observed modulations of eNOS expression are mediated by NO and represent an adaptive physiologic response.

Treatment of melasma with Pycnogenol

Melasma (or chloasma) is a common disorder of cutaneous hyperpigmentation predominantly affecting sun-exposed areas in women. The pathogenesis of melasma is not fully understood and treatments are frequently disappointing and often associated with side effects. Pycnogenol is a standardized extract of the bark of the French maritime pine (Pinus pinaster), a well-known, potent antioxidant. Studies in vitro show that Pycnogenol is several times more powerful than vitamin E and vitamin C. In addition, it recycles vitamin C, regenerates vitamin E and increases the endogenous antioxidant enzyme system. Pycnogenol protects against ultraviolet (UV) radiation. Therefore its efficacy in the treatment of melasma was investigated. Thirty women with melasma completed a 30-day clinical trial in which they took one 25 mg tablet of Pycnogenol with meals three times daily, i.e. 75 mg Pycnogenol per day. These patients were evaluated clinically by parameters such as the melasma area index, pigmentary intensity index and by routine blood and urine tests. After a 30-day treatment, the average melasma area of the patients decreased by 25.86 +/- 20.39 mm(2) (p < 0.001) and the average pigmentary intensity decreased by 0.47 +/- 0.51 unit (p < 0.001). The general effective rate was 80%. No side effect was observed. The results of the blood and urine test parameters at baseline and at day 30 were within the normal range. Moreover, several other associated symptoms such as fatigue, constipation, pains in the body and anxiety were also improved. To conclude, Pycnogenol was shown to be therapeutically effective and safe in patients suffering from melasma.

Analyses of micronuclei in exfoliated epithelial cells from individuals chronically exposed to arsenic via drinking water in inner Mongolia, China

The groundwater in Bayingnormen (Ba Men), located in Central West Inner Mongolia, China, is naturally contaminated with arsenic at concentrations ranging from 50 microg/L to 1.8 mg/L. Various adverse health effects in this region, including cancer, have been linked to arsenic exposure via drinking water. A pilot study was undertaken to evaluate frequencies of micronuclei (MN), as measures of chromosomal alterations, in multiple exfoliated epithelial cell types from residents of Ba Men chronically exposed to arsenic via drinking water. Buccal mucosal cells, airway epithelial cells in sputum, and bladder urothelial cells were collected from 19 residents exposed to high levels of arsenic in drinking water (527.5 +/- 24 microg/l), and from 13 control residents exposed to relatively low levels of arsenic in drinking water (4.4 +/- microg/L). Analytical results from these individuals revealed that MN frequencies in the high-exposure group were significantly elevated to 3.4-fold over control levels for buccal and sputum cells, and to 2.7-fold over control for bladder cells (increases in MN frequency significant at p < .001 for buccal cells; p < .01 for sputum cells; p < .05 for bladder cells). When smokers were excluded from high-exposure and control groups the effects of arsenic were observed to be greater, although only in buccal and sputum cells; approximately 6-fold increases in MN frequency occurred in these tissues. The results indicate that residents of Ba Men chronically exposed to high levels of arsenic in drinking water reveal evidence of genotoxicity in multiple epithelial cell types; higher levels of induced MN were observed in buccal and sputum cells than in bladder cells.

Enhanced nitric oxide inactivation in aortic coarctation-induced hypertension

BACKGROUND

Abdominal aortic coarctation above the renal arteries leads to severe hypertension (HTN) above the stenotic site. We have recently shown marked up-regulations of endothelial nitric oxide synthase (eNOS) in heart and thoracic aorta and of neuronal NOS (nNOS) in the brain of rats with severe aortic coarctation above the renal arteries. We hypothesize that the presence of severe regional HTN in the face of marked up-regulation of NO system may be partly due to enhanced NO inactivation by reactive oxygen species (ROS) leading to functional NO deficiency.

METHODS

Tissue nitrotyrosine (which is the footprint of NO interaction with ROS) was determined by Western blot in sham-operated control and aortic-banded (above renal arteries) rats three weeks postoperatively. Intra-arterial pressure and tissue nitrotyrosine (Western blot) were measured.

RESULTS

The banded group showed a marked rise in arterial pressure measured directly through a carotid cannula (203 +/- 9 vs. 131 +/- 2 mm Hg, P < 0.01). Compared with the sham-operated controls, the banded animals exhibited significant increases in nitrotyrosine abundance in the heart, brain, and the aorta segment above the stricture. In contrast, nitrotyrosine abundance was unchanged in the abdominal aorta segment below the stricture wherein blood pressure was not elevated.

CONCLUSION

Coarctation-induced HTN is associated with increased nitrotyrosine abundance in all tissues exposed to high arterial pressure, denoting enhanced ROS-mediated inactivation and sequestration of NO in these sites. This can, in part, account for severe regional HTN in this model. The normality of nitrotyrosine abundance in the abdominal aorta wherein blood pressure is not elevated points to the role of baromechanical factors as opposed to circulating humoral factors that were necessarily similar in both segments.

Compensatory up-regulation of nitric-oxide synthase isoforms in lead-induced hypertension; reversal by a superoxide dismutase-mimetic drug

Chronic exposure to low levels of lead causes hypertension (HTN) that is, in part, due to increased inactivation of nitric oxide (NO) by reactive oxygen species (ROS). The latter results in functional NO deficiency and compensatory up-regulation of NO synthase (NOS). We have previously shown evidence for increased hydroxyl radical (*OH) activity in rats with lead-induced HTN. Since in the biological systems *OH is primarily derived from superoxide (O2*) we hypothesize that lead-induced oxidative stress and HTN must be due to increased O2* production and as such could be ameliorated by administration of a cell-permeable O2* scavenger. We, therefore, studied the effects of the superoxide dismutase (SOD)-mimetic drug tempol (15 mmol/kg/day i.p. x 2 weeks) and placebo in lead-exposed (given lead acetate, 100 ppm in the drinking water for 12 weeks) and normal control rats. Lead exposure resulted in a marked elevation of blood pressure, a significant reduction in urinary NO metabolites (NO(chi)) excretion, and up-regulations of endothelial and inducible NOS abundance in the kidney, aorta, and heart and of neuronal NOS in the cerebral cortex and brain stem. Administration of tempol ameliorated HTN, increased urinary NO(chi) excretion, and reversed the compensatory up-regulation of NOS isoforms in rats with lead-induced HTN. These abnormalities recurred within 2 wk after discontinuation of tempol. In contrast to the lead-exposed rats, the normal control rats showed no change in either blood pressure, urinary NO(chi) excretion, or tissue NOS expression in response to either administration or discontinuation of tempol. Thus, the study supports the presence of increased O2* activity and its role in the pathogenesis of HTN and altered NO metabolism in lead-exposed animals.

Effect of microiontophoretic application of dopamine on subthalamic nucleus neuronal activity in normal rats and in rats with unilateral lesion of the nigrostriatal pathway

The subthalamic nucleus (STN) receives dopamine inputs from the substantia nigra but their implication in the pathophysiology of parkinsonism is still debated. Extracellular microrecordings were used to study the effect of microiontophoretic injection of dopamine and the D1 receptor agonist SKF 38393 on the activity of STN neurons in normal and 6-hydroxydopamine-lesioned rats under urethane anaesthesia. Dopamine and SKF induced an increase in the firing rate of the majority of STN neurons in both normal and 6-OHDA rats. In rats with 6-OHDA lesions, the percentage of firing rate increase did not differ from that of controls. When GABA, glutamate and dopamine were all applied to the same individual STN neurons, GABA induced an inhibitory effect and glutamate and dopamine caused an excitatory effect in both groups. This excitatory response was suppressed by the application of GABA. Systemic administration of apomorphine provoked a decrease in the firing rate of STN neurons in rats with 6-OHDA lesions. These results show that dopamine exerts an excitatory influence on STN neurons, suggesting that the inhibitory effect induced by the systemic injection of apomorphine is due to the GABAergic inputs from the globus pallidus as predicted by the current model of basal ganglia organization. In addition, we show that dopamine, GABA and glutamate can act on the same STN neuron and that GABA can reverse the excitatory effect of dopamine and glutamate, suggesting the predominant influence of GABAergic inputs to the subthalamic nucleus.

Intrasubthalamic injection of 6-hydroxydopamine induces changes in the firing rate and pattern of subthalamic nucleus neurons in the rat

The subthalamic nucleus (STN) receives dopaminergic projections from the substantia nigra pars compacta (SNc). To investigate the role of direct and indirect dopaminergic influences on STN neurons, the spontaneous activity was studied in four groups of animals: normal rats, rats with intrasubthalamic or intranigral injection of 6-hydroxydopamine (6-OHDA), and sham STN injection rats by using extracellular recordings 4 weeks postsurgery. After intrasubthalamic injection of 6-OHDA, the mean firing rate significantly decreased (7.29 +/- 0.39 spikes/sec, P < 0.01 vs. 11.13 +/- 0.59 spikes/sec in normal or 11.26 +/- 0.57 spikes/sec in sham group), and the percentage of STN neurons discharging regularly decreased significantly (81%, P < 0.05 vs. 90% in normal group or P < 0.01 vs. 92% in sham group) and that of bursty cells increased (19%, P < 0.05 vs. 10%; in normal group or P < 0.01 vs. 8% in sham group). In the group of rats with SNc lesion, the firing rate of subthalamic neurons did not show a significant difference (11.61 +/- 0.81 spikes/sec) compared with normal group. However, the firing pattern was dramatically changed: 74% of cells exhibited bursty pattern and only 26% of cells discharged regularly or slightly irregularly. Immunohistochemical results showed that intrasubthalamic injection of 6-OHDA induced a marked degeneration of dopaminergic cells in the lateral part of the ipsilateral SNc, whereas 6-OHDA injection into the SNc induced a total in situ lesion of dopamine cells. These results suggest that the SNc exerts an excitatory influence on STN neurons and that the loss of this dopaminergic projection could, at least partially, account for the changes in the firing pattern of STN neurons in the 6-OHDA rat model of parkinsonism.

[Speciation of metals and metalloids in biomolecules by hyphenated techniques]

This paper introduces briefly the analytical methods recently published in the literature on the speciation of arsenic, selenium and cadmium in biological samples using hyphenated techniques, HPLC-ICP-MS, HPLC-ES-MS/MS, and CE-ES-MS/MS. The coupling SEC-ICP-MS is the most popular technique for the first screening of unknown sample in view of the presence of macro molecular species of element. But due to its insufficient resolution, complementary chromatographic separations have to be carried out in order to guarantee the purity of the signal. CZE-ICP-MS is a powerful tool in trace metal speciation. In case standards and reference materials are not available, ES-MS/MS is the best technique in the characterization of metal complexes. During analysis care should be taken to avoid contamination of the sample and break-up of the original metal-protein bond during the separation process. Due to lack of standards and reference materials, the application of hyphenated technique has been looking for new species rather than determining a known compound. The difficult problems are whether a signal produced by a detector belongs to a particular compound and the identification of this compound.

Effect of severe aortic banding above the renal arteries on nitric oxide synthase isotype expression

BACKGROUND

Severe aortic stenosis above the renal arteries leads to a reduction in renal perfusion, increased renin secretion, and elevation of arterial blood pressure above the stenotic site. Nitric oxide (NO) plays an important role in regulation of renal and systemic vascular resistance, renal blood flow, and Na(+) handling. Abdominal aortic banding provides an excellent model for simultaneous testing of the effects of increased and decreased pressure, flow, and shear stress in the same animal.

METHODS

We studied protein expressions of endothelial NO synthase (eNOS), inducible NOS (iNOS), and neuroneal NOS (nNOS) isotypes in the renal cortex, renal medulla, heart, brain, and aorta segments above and below the stenosis site three weeks after abdominal aortic banding above the renal arteries. The results were compared with those obtained in the sham-operated controls. NOS isotype proteins were measured by Western blot.

RESULTS

Compared with the control group, the banded group showed significant up-regulations of eNOS, iNOS, and nNOS in renal cortex and medulla. Likewise, heart eNOS, brain nNOS, and thoracic aorta eNOS proteins were significantly increased in the banded group. However, eNOS and iNOS expressions were unchanged in the aorta segment below the stenotic site. Likewise, iNOS expression in the heart and thoracic aorta remained unchanged in the banded animals. No significant difference was found in creatinine clearance or urinary protein excretion between the two groups.

CONCLUSIONS

These findings clearly demonstrate the up-regulatory action of increased pressure on eNOS expression in the thoracic aorta and heart and of nNOS expression in the brain. These data further show up-regulation of all NOS isotypes in the kidney, which must have helped to mitigate the associated hypoperfusion.

Effect of salt loading on nitric oxide synthase expression in normotensive rats

Elevation of arterial blood pressure (BP) with high salt intake in Dahl salt-sensitive rats is associated and perhaps, in part, due to downregulation of renal and vascular production of nitric oxide (NO) and nitric oxide synthase (NOS) expressions. Several recent studies have revealed a significant increase in BP in Sprague-Dawley rats on high salt intake. Given the apparent salt sensitivity of Sprague-Dawley rats, we hypothesized that chronic high salt intake may affect NO system in these rats in a manner resembling that reported in salt-sensitive (not salt-resistant) Dahl rats. The effects of a high salt diet (chow containing 8% NaCl) of 48-h or 3-week duration was studied on immunodetectable endothelial (eNOS), inducible (iNOS), and neuronal (nNOS) NOS expressions of relevant organs in male Sprague-Dawley rats. The results were compared with those obtained in the control animals fed a regular no-added salt diet (0.2% NaCl). Consumption of a high salt diet for 3 weeks induced hypertension (HTN) (158 +/- 6 v 115 +/- 5 mm Hg, P < .01) and widespread downregulation of iNOS expression in renal cortex, renal medulla, aorta, and heart. Similarly, chronic salt loading resulted in marked downregulation of eNOS expression in renal cortex and aorta and lowered expressions of nNOS in the brain, renal cortex, and renal medulla. In comparison, short-term salt loading resulted in significant reduction of iNOS in the renal cortex and aorta and of eNOS in the aorta together with significant elevation of nNOS expression in renal medulla and brain. Thus, chronic consumption of a high salt diet resulted in moderate HTN in normotensive Sprague-Dawley rats. This was accompanied by widespread downregulation of various NOS isotypes that undoubtedly contributed to the development and maintenance of HTN in this model.

[Cloning and expression of Shiga-like toxin type II variant B gene of E. coli]

A structure sequence and a DNA fragment including the signal peptide sequence and structure sequence of Shiga-like toxin II variant B subunit gene were amplified from E. coli strain O138 by PCR. After digested with restriction endonuclease EcoRI and BamHI, the two genes were orientally inserted into the polycloning site of expression vector pYA3334 (asd+) respectively. Recombinant plasmids pB0 and pB1 were constructed and amplified in E. coli X6212 (asd-). pB0 and pB1 were then introduced into avirulent Salmonella typhimurium vaccine strain X4550 (asd-) by serial transformation through intermediate strain X3730 (asd-) to construct recombinant SLT-IIvB strain. Results of nucleotide sequencing of the cloned fragments in pB0 and pB1 revealed that they were in correct ORF of SLT-IIvB. The results of SDS-PAGE and Western-blot showed that 7.6 kD protein of SLT-IIvB antigen was expressed at pretty high level in recombinant strain X4550(pB0). The results of mice immunization indicated X4550(pB0) could initiate the host to produce specific antibodies to SLT-IIvB and LPS-O antigen of X4550. So the recombinant strain X4550 (pB0) is worth considering as a candidate vaccine strain against porcine edema disease and Salmonella typhimurium infections.

Effect of antioxidant therapy on blood pressure and NO synthase expression in hypertensive rats

Earlier studies have demonstrated evidence for increased reactive oxygen species, enhanced NO synthase (NOS) expression, and elevated NO production in spontaneously hypertensive rats (SHR). Given the negative-feedback regulation of NOS by NO, we hypothesized that enhanced NO inactivation by ROS may contribute to compensatory upregulation of NOS in SHR. The present study was designed to test this hypothesis. Eight-week-old male SHR and Wistar-Kyoto rats were treated for 3 weeks with either a placebo or the potent antioxidant, lazaroid (desmethyltirilazad, 10 mg. kg(-1). d(-1), by gastric gavage). Tail arterial blood pressure, urinary excretion of NO metabolites (ie, nitrate and nitrite), and immunodetectable NOS isotype proteins in the vascular, renal, cardiac, and cerebral tissues were measured. The placebo-treated SHR group showed a marked elevation of blood pressure and a significant upregulation of aorta, kidney, and cardiac tissue endothelial and inducible NOS (eNOS and iNOS, respectively) proteins and of brain and renal tissue neuronal NOS. Lazaroid therapy ameliorated hypertension and mitigated the upregulation of eNOS and iNOS in vascular, renal, and cardiac tissues but had limited effect on the expression of renal and brain neuronal NOS. In contrast, lazaroid therapy had no effect on blood pressure, urinary nitrate and nitrite excretion, or tissue NOS isotype expressions in the Wistar-Kyoto group. These findings support the role of oxidative stress in the genesis and/or maintenance of hypertension and compensatory upregulation of the expression of eNOS and iNOS in SHR.

Changes in the firing pattern of globus pallidus neurons after the degeneration of nigrostriatal pathway are mediated by the subthalamic nucleus in the rat

Changes in the neuronal activity of globus pallidus (GP) have been shown in animal models of parkinsonism. In order to study the implication of the subthalamic nucleus (STN) in these changes, the effects of STN lesions alone or in combination with 6-hydroxydopamine (6-OHDA) -induced damage to the substantia nigra compacta (SNc) were examined in rats using electrophysiological recordings of GP cells. In normal rats, the firing rate was 22.1+/-1.4 spikes/s. The pattern was regular in 45%, irregular in 49% and bursty in 6% of the cases. In rats with STN lesions, the firing rate of GP units (20.15+/-1.25 spikes/s) did not differ from that of normal rats and only regular (46%) and irregular (54%) cells were found; a bursty pattern was not observed. 6-OHDA lesions of the SNc induced no change in the firing rate of GP neurons (21.5+/-1.4 spikes/s, P>0.05) but a significant decrease in the percentage of regular cells (27%, P<0.001), a significant increase in burst cells (21%, P<0.001) with no change in the percentage of irregular units (52%) were observed. In rats with combined SNc and STN lesions, the firing pattern did not change from that of normal rats. The present results show that STN lesions induced the disappearance of bursts in normal rats and normalization of firing pattern in the GP units of rats with 6-OHDA lesions suggesting that the STN plays an important role in the modulation of the pattern of activity of GP neurons which may account for the therapeutic effect of STN lesions in Parkinson's disease.

[The prevention of primary liver cancer by selenium in high risk populations]

OBJECTIVE

To study the preventive effects of selenium on primary liver cancer.

METHODS

After screening of blood samples in 18,000 males from 20 to 65 years-old in Qidong, Jiangsu province (a high risk area for liver cancer), 2,065 cases of HBsAg positive, AFP negative and normal liver function (normal ALT values) were found. The subjects were randomly divided into two groups, based on their residence areas; 1,112 subjects (experimental group) received one tablet of sodium selenite (0.5 mg Se) every day and 953 subjects (control group) received one placebo tablet every day.

RESULTS

During three years of intervention and follow up, the blood selenium concentration and glutathione peroxidase activity of the subjects in the experimental group were increased and had significant difference as compared with those of the control group (P < 0.01). At the same time, the prevalence rate of micronucleus cells in peripheral blood lymphocytes in the experimental group was significantly lower than that of the control group (P < 0.01), and the incidence of new liver cancer in the experimental group (3 057.55/10(6), 34 cases out of 1,112 subjects) was significantly lower than the control group (5 981.11/10(6); 57 cases out of 953 subjects) (P < 0.01).

CONCLUSION

The results confirms that selenium supplementation in general populations lived in high risk is effective in the prevention of liver cancer and the using of selenium tablets is simple and feasible.

Identification of a hybrid-specific expressed gene encoding novel RNA-binding protein in wheat seedling leaves using differential display of mRNA

A hybrid-specific expressed cDNA fragment, designated as AG5, has been identified in wheat seedling leaves using differential mRNA display. AG5 contains an open reading frame (ORF) encoding 183 amino acid residues. Comparison with amino acid sequences in GenBank revealed that the AG5 protein is homologous to a group of Gly-rich proteins with consensus sequence-type RNA-binding domains (CS-RBD). Structural analysis showed that AG5 protein contains five motifs, including a consensus sequence-type RNA-binding domain near its N-terminus, arginine/aspartic acid repeats and a Gly-rich region in its center, a Cys-X2-Cys-X4-His-X4-Cys (CCHC) zinc finger motif in the Gly-rich region, and TrySer2ArgAsp2Arg repeats towards its C-terminus. Of all previously described RNA-binding proteins, only RZ-1 from tobacco has a similar structure to the AG5 protein, but RZ-1 lacks a TrySer2ArgAsp2Arg repeat motif, indicating that the two proteins may belong to a family of closely related proteins in plants. The possible role of AG5 and its relation to wheat heterosis are discussed.

Down-regulation of renal endothelial nitric oxide synthase expression in experimental glomerular thrombotic microangiopathy

Infection with certain strains of Escherichia coli and endotoxemia results in renal glomerular thrombotic microangiopathy (TMA) characterized by endothelial swelling and prominent glomerular microthrombus formation. Nitric oxide (NO) is an endogenous biologic modulator with diverse physiologic functions including vasodilation and inhibition of platelet adhesion and aggregation. NO is synthesized from conversion of L-arginine to L-citrulline by a family of NO synthases (NOS), which include constitutive and inducible isoforms. Indirect evidence supports the hypothesis that TMA is associated with depressed intrarenal NO production. However, the effect of TMA on renal tissue NOS expression has not been fully elucidated. We studied rats with TMA induced by iv bolus injection of high dose (20 mg/kg) E. coli endotoxin. Subgroups of six animals each were sacrificed before or at 30, 90, 180, 360, and 720 minutes after the administration of endotoxin. Renal histology and tissue expression of endothelial and inducible nitric oxide synthases (eNOS and iNOS) were examined. Additionally, we examined the effect of endotoxin on glomerular NO production, and eNOS and iNOS protein expression in vitro. Glomerular capillary thrombosis developed by 180 minutes after endotoxin administration in approximately half of the animals. The glomeruli without thrombotic lesions apparent by light microscopy disclosed early signs of TMA characterized by endothelial swelling, platelet accumulation/adhesion, and patchy fibrinogen deposition. These morphologic changes were associated with a marked reduction of renal tissue eNOS expression beyond 180 minutes after the endotoxin administration. The fall in eNOS expression was coupled with a significant rise in iNOS protein abundance, which was expressed largely by glomerular circulating neutrophils and endothelial cells, peritubular vascular endothelium, and collecting ducts of cortex and medulla. In vitro incubation of isolated glomeruli with endotoxin also resulted in a marked reduction in eNOS expression and a significant rise in iNOS content. Administration of E. coli endotoxin leads to a sustained fall in renal eNOS expression both in vivo and in vitro. The associated decline in intrarenal endothelial NO production/availability may result in renal vasoconstriction and a hypercoagulative state, which may contribute to the pathogenesis of endotoxin-induced TMA.

Analysis of K-ras and p53 mutations in mesotheliomas from humans and rats exposed to asbestos

Malignant mesothelioma is known to be associated with asbestos exposure. However, the mechanism of mesothelial carcinogenesis in relation to the activation of proto-oncogenes or inactivation of tumor suppressor genes remains unclear. In this study, the PCR-Primer Introduced Restriction Site (PCR-PIRS) assay was employed to examine mutations in the K-ras proto-oncogene in mesothelioma tissues from workers exposed to asbestos and from rats treated with asbestos. Mutations in exons 5-8 of the p53 tumor suppressor gene were determined by direct DNA sequence analysis. Results of the PCR-PIRS analysis revealed no mutations in codons 12, 13 or 61 of the K-ras gene in any of the 17 human or 22 rat mesothelioma tissue samples. These results were confirmed by direct DNA sequence analysis. No mutations were found in exons 5-8 of the p53 gene in any of the mesothelioma tissue samples analyzed. These results and the results reported by others indicate that the K-ras proto-oncogene and p53 tumor suppressor gene may not play a critical role in the induction of mesothelioma by asbestos either in humans or in rats.

High frequency stimulation of the STN influences the activity of dopamine neurons in the rat

The effect of high frequency stimulation (HFS) of the subthalamic nucleus (STN) on the spontaneous activity of substantia nigra pars compacta (SNc) dopaminergic neurons was investigated in normal rats and in rats with globus pallidus (GP) lesions. In normal rats, the spontaneous activity of SNc neurons did not significantly differ from that of rats with GP lesions (4.2+/-2.2 versus 4.4+/-2.6 spikes/s). STN-HFS induced an increase of firing rate in the majority of tested cells in normal (76%) and GP-lesioned rats (73%) with an after-effect of 34.4+/-3.4 and 33.2+/-3.1 s, respectively. These results demonstrate that STN-HFS influences the activity of the SNc dopaminergic neurons by increasing their firing rate and that this increase of activity is independent of the globus pallidus.

Inhibition of constitutively activated Stat3 signaling pathway suppresses growth of prostate cancer cells

Overexpression of interleukin 6, a downstream target of the GBX2 homeobox gene, has been linked to the progression of prostate cancer. The Janus kinase-signal transducers and activators of transcription signaling pathway transmits interleukin 6-mediated signals from cell surface receptors to the target genes in the nucleus and is critical in mediating cellular growth and differentiation. We demonstrate that cells derived from both rat and human prostate cancers have constitutively activated Stat3, with Stat3 activation being correlated with malignant potential. Blockade of activated Stat3 by ectopic expression of a dominant-negative Stat3 in human prostate cancer cells significantly suppresses their growth in vitro and their tumorigenicity in vivo. Furthermore, the Janus kinase inhibitor, tyrphostin AG490, inhibited the constitutive activation of Stat3 and suppressed the growth of human prostate cancer cells. These results indicate that activation of Stat3 signaling is essential in the progression of prostate cancer cells and suggest that targeting Stat3 signaling may yield a potential therapeutic intervention for prostate cancer.

Interleukin-6 induces prostate cancer cell growth accompanied by activation of stat3 signaling pathway

BACKGROUND

Interleukin-6 (IL-6) is a pleiotropic cytokine that regulates growth and differentiation of various types of malignant tumors, including prostate carcinomas. The levels of IL-6 are elevated in sera of patients with metastatic prostate cancer. In this study, we evaluate the role of IL-6 in the growth regulation of prostate cancer cells.

METHODS

Expression of IL-6 and its receptors in human prostate cancer cells was measured by ELISA and RT-PCR. The effects of IL-6 on cell growth were evaluated by ectopically expressing IL-6 cDNA into IL-6-negative LNCaP human prostate cancer cells. Stat3 DNA binding activities were analyzed by electromobility shift assay and supershift assay.

RESULTS

Expression of IL-6 was detected in the androgen-insensitive prostate cancer cell lines (i.e. , TSU, PC3, and DU145), but not in the androgen-sensitive LNCaP cell line. IL-6 receptors, including both IL-6-specific receptor alpha chain and gp130 signal transducer, are expressed in all human prostate cancer cell lines (i.e., LNCaP, TSU, PC3, and DU145). Overexpression of IL-6 by ectopically expressing IL-6 into IL-6-negative LNCaP human prostate cancer cells significantly increased clonogenic ability and cell proliferation in vitro compared to the IL-6-negative parental LNCaP cells and the antisense controls. This growth stimulation by IL-6 was accompanied by activation of the Stat3 signaling transduction pathway.

CONCLUSIONS

IL-6 is an autocrine growth factor for LNCaP human prostate cancer cells; the effects of IL-6 on prostate cancer cell growth are mediated through the Janus kinase-signal transducers and activators of transcription (JAK-STAT) signaling pathway.

Effect of Astragalin on matrix secretion and beta 1 integrin mRNA expression in human mesangial cells

OBJECTIVE

To investigate the effect of Astragalin on human renal mesangial cells.

METHODS

Cultured human mesangial cells were treated with Astragalin and Astragalin serum in different concentrations in the presence or absence of PDGF-BB, the proliferation and type IV collagen secretion of mesangial cells were measured by MTT assay and ELISA, and expression of beta 1 integrin gene was estimated by reverse transcription-polymerase chain reaction (RT-PCR) method, suspectively.

RESULTS

After 72 hours Astragalin or Astragalin serum treatment, the proliferation of mesangial cells induced by PDGF-BB was inhibited significantly in a dose-dependent manner compared with untreated controls (P < 0.05 and P < 0.01). After 24 hours of Astragalin or Astragalin serum treatment, the secretion of type IV collagen protein in presence of PDGF-BB was significantly decreased and beta 1 integrin mRNA level decreased significantly compared with untreated control (P < 0.05, P < 0.01).

CONCLUSIONS

Astragalin inhibits cell proliferation and matrix over-synthesis which might be mediated, at least, partly by decrease of beta 1 integrin gene over-expression. The study suggested that Astragalin might play a role in preventing the progression of chronic renal diseases.

Nitric oxide synthase expression in the course of lead-induced hypertension

We recently showed elevated reactive oxygen species (ROS), reduced urinary excretion of NO metabolites (NOx), and increased NO sequestration as nitrotyrosine in various tissues in rats with lead-induced hypertension. This study was designed to discern whether the reduction in urinary NOx in lead-induced hypertension is, in part, due to depressed NO synthase (NOS) expression. Male Sprague-Dawley rats were randomly assigned to a lead-treated group (given lead acetate, 100 ppm, in drinking water and regular rat chow), a group given lead and vitamin E-fortified chow, or a normal control group given either regular food and water or vitamin E-fortified food for 12 weeks. Tail blood pressure, urinary NOx excretion, plasma malondialdehyde (MDA), and endothelial and inducible NOS (eNOS and iNOS) isotypes in the aorta and kidney were measured. The lead-treated group exhibited a rise in blood pressure and plasma MDA concentration, a fall in urinary NOx excretion, and a paradoxical rise in vascular and renal tissue eNOS and iNOS expression. Vitamin E supplementation ameliorated hypertension, lowered plasma MDA concentration, and raised urinary NOx excretion while significantly lowering vascular, but not renal, tissue eNOS and iNOS expression. Vitamin E supplementation had no effect on either blood pressure, plasma MDA, or NOS expression in the control group. The study also revealed significant inhibition of NOS enzymatic activity by lead in cell-free preparations. In conclusion, lead-induced hypertension in this model was associated with a compensatory upregulation of renal and vascular eNOS and iNOS expression. This is, in part, due to ROS-mediated NO inactivation, lead-associated inhibition of NOS activity, and perhaps stimulatory actions of increased shear stress associated with hypertension.

Nitric oxide synthase isotype expression in salt-sensitive and salt-resistant Dahl rats

Previous studies have suggested that salt-sensitive hypertension in humans and experimental animals may in part be due to dysregulation of the L-arginine/nitric oxide system. This study was conducted to determine the endothelial, inducible, and neuronal nitric oxide synthase expressions in the kidney, heart, aorta, and brain of salt-sensitive and salt-resistant Dahl rats. We studied salt-sensitive and salt-resistant Dahl rats maintained on high- (8%) and regular- (0.2%) salt diets for 3 weeks. Blood pressure was modestly elevated in both Dahl salt-sensitive and salt-resistant rats consuming regular diet and severely increased in sensitive but not resistant rats consuming the high-salt diet. The Dahl salt-sensitive animals showed a significant reduction in kidney, heart, and aorta inducible nitric oxide synthase protein abundance on the regular diet, with further reductions on the high-salt diet. In addition, the high-salt diet markedly downregulated endothelial nitric oxide synthase expression in the kidney and aorta but not in the heart of the Dahl salt-sensitive animals. The rise in blood pressure in the Dahl salt-sensitive rats on the high-salt diet was accompanied by a significant elevation of brain neuronal nitric oxide synthase protein. In contrast, salt-resistant animals showed no change in heart, kidney, and aorta endothelial or brain neuronal nitric oxide synthase and considerably less intense changes in inducible isotype than that seen in the salt-sensitive group in response to the high-salt diet. In conclusion, the study revealed a marked downregulation of inducible nitric oxide synthase in the Dahl salt-sensitive rats on the regular diet, with further reductions on the high-salt diet. Furthermore, Dahl salt-sensitive rats consuming the high-salt diet showed significant reductions of kidney and aorta endothelial nitric oxide synthase and an upregulation of brain neuronal nitric oxide synthase expression.

[Expression and characteristics of laryngeal carcinoma-associated antigen]

OBJECTIVE

To study the characteristics of laryngeal carcinoma-associated antigen (LCAA) and its expression on laryngeal carcinoma tissue.

METHODS

The binding of a cocktail monoclonal antibodies Lc9, Lc11, Lc12 to human laryngeal squamous-cell carcinoma, laryngeal precancerous lesions and normal laryngeal mucosa was examined by immunohistochemical method. LCAA isolated and purified by gel-filtration, and chromotography from 3 laryngeal squamous-cell carcinomas. The reactivity of the purified antigen was determined after treatment with trypsin, NaIO4, methanol and heating.

RESULTS

The positive rate of LCAA expression in 90 cases of laryngeal carcinoma, 14 cases of precancerous lesions and in 10 cases of normal laryngeal mucosa was 97.7%, 50.0% and 0, respectively. LCAA was a glycoprotein, moderately heat stable. The purified antigen gave two bands of apparent molecular weights of 61,400 and 56,500 on SDS-PAGE and Western blot.

CONCLUSION

The results provide a basis for immunoimaging diagnosis and targeting chemotherapy for laryngeal cancer.

[On the problems of fitting linear regression models for hierarchically structured data in medical research]

There are a large number of the hierarchically structured data in the field of medical sciences, which have been analyzed usually by conventional linear regression models. The objective of this paper is to explore the problems and the relationship of parameter estimates of the three common linear regression models in fitting the hierarchically structured date, and the correction of the precision of parameter estimates. It is shown that the estimate of parameter and it's precision of linear regression models is related to the variation of independent variable between and within level 2 units, and the difference of residual estimates is associated with the difference of parameter estimates. The three common linear regression models are all inappropriate for the hierarchically structured data, but the standard error of the level 1 combined model can be corrected by variance inflation factor in conditions.

[Application of intraclass correlation coefficient to reliability assessment]

To evaluate the reliability of questionnaire and expound the simple method of calculating and testing the intraclass correlation coefficient (ICC), the authors gave an example of how to simply calculate and conduct the hypothesis testing of ICC by using the analysis table of variance. The results demonstrated a high test-retest reliability of the illustrative questionnaire. By using ANOVA table, the calculation and hypothesis testing of the ICC is easy to do. The method can be used in the analysis of quantitative data, and categorical data as well.

[Likelihood ratio and ROC curve in evaluation of iron parameters for diagnosing iron deficiency]

OBJECTIVE

To evaluate the value of iron parameters in diagnosing iron deficiency (ID).

METHODS

Cross-sectional study was performed for diagnostic tests. Ninety consecutive patients with anemia including iron deficiency anemia without chronic diseases (36 cases), chronic diseases (54) were divided into chronic diseases without ID(ACD) (23 cases) and chronic diseases with ID(CDID) (31) by bone marrow iron staining. The exclusion criteria included hemolytic anemia, deficiency of Vitamin B12 or folic acid, blood transfusion, taking iron preparations within one month and hematological malignancies. By using absence of bone marrow iron as gold standard of ID, we compared the diagnostic powers in the diagnosis of iron deficiency for sTfR, serum iron, total iron binding capacity, serum ferritin (SF), transferrin saturation and the presence of hypochromic red cells by analyzing the likelihood ratio, the area under ROC(AUCROC).

RESULTS

AUCROC for sTfR in determining ID in groups IDA + CDID vs. ACD, IDA vs. ACD and CDID vs. ACD were 0.9 (95% CI: 0.82-0.98), 0.96(0.9-0.99) and 0.84 (0.72-0.96) respectively, AUCROC for SF in above groups 0.87 (95% CI: 0.77-0.87), 0.94(0.86-0.99) and 0.77(0.63-0.91) respectively. AUCROC for other iron parameters in determining iron deficiency in chronic diseases was lower than 70%.

CONCLUSION

ROC and LR are useful tools for evaluating iron parameters in diagnosing iron deficiency. TfR is a best parameter in determining iron deficiency in chronic diseases than SF and other iron parameters.

[Studies on localization of laryngeal carcinoma associated antigen by immunoelectromicroscopy]

OBJECTIVE

To study the localization of laryngeal carcinoma associated antigen (LCAA) in the carcinoma tissue.

METHODS

Ninety cases of laryngeal carcinoma and 14 cases of laryngeal precancerous lesion and 10 cases of normal laryngeal mucosa were detected with three strains of monoclonal antibodies LC9, LC11, LC12 by immunochemistry. The positive sections of laryngeal carcinoma were observed under light microscope and electromicroscopy.

RESULTS

The positive rates of LCAA were dramatically higher than that in normal epithelial and precancerous tissues (P < 0.01). The results showed that the mixed monoclonal antibody had tissue specificity. The MLC associated antigens only distributed in cell membranes and/or cytoplasm. No cell nucleus was stained.

CONCLUSION

The LCAA is mainly located in cell membranous structure. This study may provide morphological basis for immunoimaging diagnosis and targeting chemotherapy by application of laryngeal carcinoma McAb.

Nitric oxide metabolism in erythropoietin-induced hypertension: effect of calcium channel blockade

Long-term administration of erythropoietin (EPO) frequently causes hypertension in humans and animals with chronic renal failure (CRF). We recently demonstrated that EPO-induced hypertension is hematocrit independent and accompanied by elevated cytosolic [Ca2+]i and nitric oxide (NO) resistance. This study was undertaken to examine the effects of therapy with EPO alone or together with calcium channel blockade on NO metabolism. Urinary excretion of NO metabolites (NOx) and thoracic aorta and kidney endothelial and inducible NO synthases (eNOS and iNOS) were studied in 4 groups of 6 nephrectomized rats treated with either placebo, EPO, the calcium channel blocker felodipine, or EPO plus felodipine for 6 weeks. A group of sham-operated placebo-treated animals served as control. The placebo-treated CRF group exhibited moderate hypertension, elevated basal and depressed stimulated platelet [Ca2+]i, reduced urinary NOx excretion, and diminished vascular and renal eNOS and iNOS proteins. EPO therapy further raised blood pressure and increased resting and stimulated [Ca2+]i but did not change NOx excretion or NOS proteins. Concurrent administration of felodipine abrogated EPO-induced hypertension, normalized resting and stimulated [Ca2+]i, and increased NOx excretion and eNOS and iNOS proteins. Thus, EPO therapy leads to marked increases in blood pressure and resting and stimulated [Ca2+]i. These abnormalities are ameliorated by calcium channel blockade, which restores [Ca2+]i to normal and increases vascular and renal NOS expression.

Depressed renal and vascular nitric oxide synthase expression in cyclosporine-induced hypertension

BACKGROUND

Introduction of cyclosporine (CsA) for clinical use has greatly enhanced the outcome of organ transplantation. However, CsA can cause nephrotoxicity and hypertension (HTN). This study was designed to test the hypothesis that CsA-induced HTN is related to depressed nitric oxide (NO) production.

METHODS

Urinary excretion of NO metabolites (NOx) and endothelial and inducible NO synthase (eNOS and iNOS) proteins were determined in thoracic aortas and kidneys of CsA-treated (given CsA 18 mg/kg/day for 3 weeks) and placebo-treated rats. In addition, renal tissue eNOS and iNOS mRNA and aorta iNOS activity were measured.

RESULTS

CsA administration resulted ina significant rise in arterial blood pressure (BP) coupled with a steady decline in urinary NOx excretion, suggesting depressed NO production. This was accompanied by a significant reduction in iNOS protein abundance in the kidney and thoracic aorta but no change in eNOS protein abundance. The fall in renal iNOS protein in CsA-treated rats was accompanied by a parallel decline in iNOS mRNA abundance and enzymatic activity.

CONCLUSION

Administration of CsA for three weeks resulted in a significant rise in BP together with marked reductions in urinary NOx excretion, and renal and vascular iNOS expression. These observations suggest that CsA-induced HTN may be, in part, related to impaired NO production. If true, strategies designed to restore NO availability may mitigate HTN and other vascular complications of CsA therapy.

Role of endothelin and nitric oxide imbalance in the pathogenesis of hypoxia-induced arterial hypertension

BACKGROUND

We have recently demonstrated that prolonged hypobaric hypoxia can lead to a hematocrit-independent sustained arterial hypertension (HTN) in genetically normotensive Sprague-Dawley rats. The rise in blood pressure in the hypoxic animals was accompanied by a marked but transient increase in plasma endothelin level. In addition, hypoxia has been shown to decrease nitric oxide (NO) production by cultured endothelial cells. This study was designed to test the hypothesis that hypoxia-induced HTN may be mediated by increased endothelin and/or decreased NO production.

METHODS

Blood pressure, plasma endothelin and urinary NO metabolites (NOx)were monitored in rats during a 24-hour exposure to hypobaric hypoxia (air pressure = 390 mm Hg). The results were compared with hypoxia (air pressure = 390 mm Hg). The results were compared with those obtained in animals maintained under normoxic condition (control group). To test the possible role of excess endothelin and depressed NO production, the studies were repeated using subgroups of animals treated with either an endothelin receptor ET-A/B blocker (L-754,142) or L-arginine.

RESULTS

The untreated hypoxic group exhibited a threefold rise in plasma endothelin and a threefold fall in urinary NOx, prior to the onset of HTN. Endothelin receptor blockade led to a further fall in urinary NOx excretion and failed to mitigate HTN. In contrast, L-arginine supplementation improved the urinary NOx excretion and prevented HTN. Neither therapy affected the hypoxia-induced erythrocytosis.

CONCLUSIONS

We conclude that hypoxia-induced HTN is associated with depressed NO production and can be mitigated by L-arginine supplementation.

Upregulation of renal and vascular nitric oxide synthase in young spontaneously hypertensive rats

The available data on the role of the L-arginine/nitric oxide (NO) pathway in the genesis of hypertension in spontaneously hypertensive rats (SHR) are limited and contradictory. In an attempt to address this issue, male SHR were studied during the early phase of evolution of hypertension (age 8 to 12 weeks) to distinguish the primary changes of NO metabolism from those caused by advanced hypertension, vasculopathy, and aging late in the course of the disease. A group of age-matched male Wistar-Kyoto rats (WKY) served as controls. The SHR exhibited a marked rise in arterial blood pressure and a significant increase in urinary excretion and plasma concentration of NO metabolites (nitrite/nitrate [NOx]). Likewise, the SHR showed a significant elevation of thoracic aorta NO synthase (NOS) activity coupled with significant increases of kidney, aorta, inducible NOS (iNOS), and endothelial NOS (eNOS) proteins. In an attempt to determine whether the enhanced L-arginine/NO pathway is a consequence of hypertension, studies were repeated using 3-week-old animals before the onset of hypertension. The study revealed significant increases in urinary NOx excretion as well as vascular eNOS and renal iNOS proteins. In conclusion, the L-arginine/NO pathway is upregulated in young SHR both before and after the onset of hypertension. Thus, development of hypertension is not due to a primary impairment of NO production in SHR. On the contrary, NO production is increased in young SHR both before and after the onset of hypertension.

Decreased endothelial nitric oxide synthase in gastric mucosa of rats with chronic renal failure

According to recent reports, chronic renal failure (CRF) increases the susceptibility of gastric mucosa to injury. Since nitric oxide plays a major role in gastric mucosal defense and injury, we investigated, in rats with CRF produced by five-sixths nephrectomy and in control rats, the expression of nitric oxide synthase(NOS) in the stomach and measured mucosal and submucosal gastric blood flow. In CRF rats, gastric mucosal blood flow was significantly reduced compared with control rats, whereas submucosal and serosal blood flow was significantly increased. CRF significantly decreased endothelial NOS (eNOS) mRNA abundance by 53% (P < 0.01) and reduced expression of eNOS protein by 42% (P < 0.01) compared with the controls. Enzyme activity of eNOS was significantly reduced in gastric mucosa of CRF rats (P < 0.05). These data are consistent with reduced gastric mucosal blood flow in CRF rats and can explain altered susceptibility of gastric mucosa to injury in CRF rats.

Downregulation of nitric oxide synthase in chronic renal insufficiency: role of excess PTH

The available data on the effect of chronic renal failure (CRF) on nitric oxide (NO) metabolism are limited and contradictory. We studied rats with CRF 6 wk after a five-sixths nephrectomy and compared the results with those in the sham-operated controls, felodipine-treated CRF, and parathyroidectomized (CRF-PTX) animals. CRF was produced by surgical resection of the upper and lower thirds of the left kidney, followed by contralateral nephrectomy. We chose this model, as opposed to that produced by renal artery branch ligation, because the latter causes exuberant hypertension (HTN), which independently affects NO metabolism. The CRF group exhibited a mild HTN coupled with elevated basal platelet cytosolic Ca2+ concentration ([Ca2+]i), blunted hypotensive response to L-arginine, decreased hypertensive response to NO synthase (NOS) inhibitor, NG-monomethyl-L-arginine, and normal hypotensive response to NO donor, sodium nitroprusside. This was associated with a significant reduction in urinary excretion of stable NO metabolites (NOX) and depressed NOS activity, as well as endothelial and inducible NO synthase (eNOS and iNOS, respectively) protein contents of thoracic aorta and the remnant kidney in the CRF animals. Calcium channel blockade and PTX lowered blood pressure, increased urinary NOX, and enhanced vascular NOS activity, as well as eNOS and iNOS protein expressions in the tested tissues. Thus CRF animals exhibited significant reductions in vascular NOS activity and eNOS and iNOS expressions. These abnormalities were reversed by calcium channel blockade and PTX, suggesting the possible causal role of CRF-induced dysregulation of [Ca2+]i.

Egr-1 inhibits apoptosis during the UV response: correlation of cell survival with Egr-1 phosphorylation

UV irradiation of normal or immortalized cells induces a rapid increase in the expression of several transcription factors and is thought to serve a protective function. The human fibrosarcoma cell line, HT1080 clone H4, expresses almost undetectable levels of Egr-1 and does not respond to UV-C irradiation by the induction of Egr-1. The H4 cells are hypersensitive to UV which induces apoptosis and reduces clonogenicity. The introduction of exogenous Egr-1 into H4 (H4E9 and H4E4 cell-lines) confers protection from UV damage as measured by a number of assays. In both NIH3T3 (with inducible Egr-1) and H4E9 (constitutive Egr-1) cells, UV irradiation gave enhanced transactivation of Egr-1 reporters that correlated with phosphorylated Egr-1. Studies using inhibitors indicated that protein kinase-C and tyrosine kinases are involved in the anti-apoptotic effects of Egr-1 after UV damage. This is the first description of a biological effect of phosphorylated Egr-1.

Lead-induced hypertension: interplay of nitric oxide and reactive oxygen species

An elevation of mean blood pressure was found in rats treated with low lead (0.01% lead acetate) for 3 months, as contrasted to paired Sprague-Dawley control rats. In these rats, measurement of plasma and urine endothelins-1 and -3 revealed that plasma concentration and urinary excretion of endothelin-3 increased significantly after 3 months (plasma: lead group, 31.8+/-2.2, versus controls, 23.0+1.7 pg/mL, P<.001; urinary excretion: lead group, 46.6+11.7, versus controls, 35.6+6.7 pg/24 h, P<.05), whereas endothelin-1 was unaffected. Plasma and urinary nitric oxide (NO) and cyclic GMP concentrations were not significantly changed. However, assay of plasma and kidney cortex malondialdehyde by high-pressure liquid chromatography, as a measure of reactive oxygen species, was elevated in lead-treated rats compared with that in control rats (plasma: lead group, 4.74+1.27, versus controls, 2.14+.49 micromol/L, P<.001; kidney cortex: lead group, 28.75+3.46, versus controls, 16.38+2.37 nmol/g wet weight, P<.001). There was increased NO synthase activity in lead-treated rat brain cortex and cerebellum. In lead-treated rat kidney cortex, the endothelial constitutive NO synthase protein mass was unaffected, whereas the inducible NO synthase protein mass was increased. These data suggest a balance between increased NO synthesis and degradation (by reactive oxygen species) in lead-treated rats, which results in normal levels of NO. Thus, the hypertension may be related to an increase in the pressure substances, endothelin-3 and reactive oxygen species, rather than to an absolute decrease in nitric NO.

Advanced glycation end products in human penis: elevation in diabetic tissue, site of deposition, and possible effect through iNOS or eNOS

OBJECTIVES

We hypothesized that advanced glycation end product (AGE) formation contributes to erectile dysfunction (ED) by quenching nitric oxide. Our first goal was to identify the specific AGE pentosidine in the diabetic human penis. Because AGE-mediated effects may involve inducible nitric oxide synthase (iNOS), we performed immunohistochemical and Western blot analysis of diabetic and nondiabetic human penile tissue for iNOS. Finally, because AGEs may act intracellularly to affect proteins, we set out to identify endothelial NOS (eNOS) in the human penis as an initial step in examining a possible intracellular interaction between eNOS and AGEs.

METHODS

We performed high-performance liquid chromatographic analysis of diabetic human penile corpus cavernosum and serum for pentosidine and performed immunohistochemical, electron microscopic (EM), and Western blot analysis of the diabetic and nondiabetic penile corpus cavernosum and tunica for pyrraline, iNOS, and eNOS (and neural NOS [nNOS] for comparative purposes) via standard methods.

RESULTS

We found a significant elevation of pentosidine in the penile tissue but not the serum of diabetic patients (average age 55.6 +/- 2.3 years) compared with that of nondiabetic patients (average age 61.8 +/- 3.6 years). Pentosidine was 117.06 +/- 9.19 pmol/mg collagen in the diabetic tunica versus 77.58 +/- 5.5 pmol/mg collagen in the nondiabetic tunica (P < 0.01) and 74.58 +/- 8.49 pmol/mg collagen in the diabetic corpus cavernosum versus 46.59 +/- 2.53 pmol/mg collagen in the nondiabetic corpus cavernosum (P < 0.01), suggesting a tissue-specific effect of the AGEs. We localized the site of deposition of the specific AGE pyrraline to the human penile tunica and the penile corpus cavernosum collagen. Immunohistochemical and EM analysis localized eNOS and iNOS to the cavernosal endothelium and smooth muscle. Western blot analysis in 6 patients revealed the following: iNOS, but no eNOS, in penile tissue from 1 insulin-dependent diabetic man; eNOS only in 1 man after radical prostatectomy; both eNOS and iNOS in 2 men with Peyronie's disease, as well as in 2 other men with impotence and hypertension. Finally, the specific iNOS inhibitor PNU-19451A significantly augmented relaxation of precontracted human cavernosal tissue, from 64.7% +/- 5.58 to 80.03% +/- 4.55 at 10 microM acetylcholine and 65.06% +/- 2.84 to 86.16% +/- 3.96 at 0.1 mM acetylcholine (n = 4, P < 0.002 and P < 0.02, respectively).

CONCLUSIONS

AGEs are elevated in diabetic human penile tissue, but not in serum, and are localized to the collagen of the penile tunica and corpus cavernosum. We identified eNOS and iNOS in the human penile cavernosal smooth muscle and endothelium. The augmentation of cavernosal relaxation with a specific iNOS inhibitor, combined with the identification of iNOS protein, but not eNOS, in a patient with severe diabetes and ED, allows for speculation of a pathophysiologic mechanism for AGE-mediated ED via upregulation of iNOS and downregulation of eNOS. These data provide further insight into the mechanisms of advanced glycation end product-mediated ED and provide a foundation for further study.

Altered nitric oxide metabolism and increased oxygen free radical activity in lead-induced hypertension: effect of lazaroid therapy

Chronic exposure to low levels of lead results in sustained hypertension (HTN) in humans and experimental animals. The mechanism of lead-induced HTN remains unclear. We investigated the possible role of reactive oxygen species (ROS) and their impact on nitric oxide (NO) metabolism in lead-induced HTN. Male Sprague-Dawley rats were treated with lead (100 ppm in drinking water) for twelve weeks. They were then treated with either the potent antioxidant, lazaroid (des-methyl-tirilazad, 5 mg/kg i.p., twice daily) (Pb-Lz group) or placebo (Pb group) for two weeks and monitored for an additional two weeks. A group of normal animals served as controls (N = 6 in each group). Lead administration resulted in marked HTN together with a significant rise in plasma concentration of lipid peroxidation product, malondialdehyde (MDA, reflecting increased ROS generation) and a twofold reduction in urinary excretion of NO metabolites, that is, total nitrates and nitrites (NOx). Lazaroid therapy led to prompt normalization of blood pressure, plasma MDA and urinary NOx. In contrast, blood pressure and plasma MDA remained elevated, and recovery of urinary NOx excretion was slow with placebo therapy. No significant difference was found in creatinine clearance between the study groups during the observation period. Thus, chronic lead exposure resulted in marked HTN coupled with increased ROS production and decreased urinary NOx excretion. Administration of the potent antioxidant, lazaroid, abrogated HTN and reversed the abnormalities of plasma MDA and urinary NOx excretion, thus supporting the role of ROS in lead-induced HTN in this model.

Reciprocal modulation between Sp1 and Egr-1

Many ubiquitously expressed genes, including oncogenes, lack a proximal TATA or CAAT box but have a region of G + C-rich sequences that appears to replace the usual promoter initiation site. The zinc-finger protein Sp1 is one of the prevalent activators of these genes. The Egr-1 zinc-finger protein has a similar binding site and if the two sites occur in the same region, a variety of activation or inhibitory responses may be obtained. We show that competition between the two factors for overlapping sites on growth-promoting genes could explain why the overexpression of Egr-1 suppresses transformed growth in a number of cell types [Huang et al. (1995): Cancer Res 55:5054-5062; Huang et al. (1997): Int J Cancer]. We demonstrate here that Egr-1 and Sp1 can bind to the same G + C-rich sites and that Egr-1 can displace Sp1 and hence inhibit its activity. We measured the responses of synthetic consensus binding sites and natural promoter sequences linked to a reporter gene and showed that Egr-1 inhibited the activation of transcription by Sp1 on overlapping Sp1/Egr-1 sites. In contrast, Sp1 activity could be augmented by Egr-1 at nonoverlapping sites in the Egr-1 gene promoter, in transient reporter gene studies in Drosophila SL2 cells. In addition, over-expression of exogenous Sp1 in mammalian cells, also leads to increased Egr-1 protein expression, which further inhibits Sp1 transactivation of numerous genes. Therefore, we can account for some of the complex responses of G + C-rich enhancer/promoters by a form of "facilitated inhibition" of Sp1 by Egr-1 at overlapping sites.

[Non-parametric testing for independence in data]

In this paper, we have discussed the important effects of data independence on statistic results, and have explained in detainl the non-parametric testing for independence, which can facilitate medical researchers to use statistical methods for solving their problems.

[Primary study on the sensitivity of cytokinesis blocked micronucleus assay in CHL cells]

Studies were performed to determine the cytochalasin B induced binucleated cell percentage influenced by clastogens and aneuploidgens and to compare the efficacy of cytokinesis blocked binucleated cells for scoring micronuclei with that of the conventional mononucleated method following the treatment with mitomycin C, methyl methanesulforate, colchicin and chloral hydrate. The results showed that mitomycin C decreased the binucleated cell percentage induced by cytochalasin B, whereas colchicin increased the frequencies of binucleated cells. The frequencies of micronuclei in binucleated cells were not significantly higher than those in the conventional mononucleated cells. The results suggest that cytokinesis blocked method is not more sensitive than the conventional method for scoring micronuclei. The factors that may influence the cytokinesis blocked micronucleus assay have been discussed.

Up-regulation of renal and vascular nitric oxide synthase in iron-deficiency anemia

Anemia is frequently associated with increased cardiac output and reduced vascular resistance. The latter has been attributed to reduced inactivation of nitric oxide (NO) by hemoglobin. We hypothesized that in addition to reducing NO inactivation, anemia may up-regulate NO production. To test this hypothesis, male Sprague-Dawley rats with chronic iron-deficiency anemia (produced by multiple phlebotomies and an iron-free diet) were studied. The results were compared with those obtained in a group of normal control animals. The anemic group showed marked increases in urinary excretion, plasma concentration, and renal and aorta tissue contents of NO metabolites (total nitrates and nitrites, NOx). This was accompanied by a significant rise in urinary excretion of cGMP, the second messenger for NO. In addition, NO synthase (NOS) activity and endothelial constitutive (ecNOS) and inducible NOS (iNOS) proteins of the thoracic aorta were markedly increased in the anemic group. Likewise, renal tissue ecNOS and iNOS proteins were greatly increased in the anemic animals. NOS activity and protein values were inversely related to hematocrit and directly related to plasma, tissue and urinary NOx. The constellation of these findings points to an increased NOS expression and NO production as opposed to the mere reduction of NO inactivation in iron-deficiency anemia. Further studies are planned to determine the mechanism of NOS up-regulation in iron-deficiency anemia.

[Study on the analysis of organogermanium compounds by ion chromatography]

A new high performance ion exchange chromatographic method for separation and determination of three organogermanium compounds beta-carboxyethylgermanium sesquioxide (I), beta-(alpha-methyl) carboxyethylgermanium sesquioxide (II) and di-(beta-carboxyethyl) germanium hydroxide (III) has been developed. A Dionex DX-300 Ion Chromatograph equipped with a Dionex PED-II pulsed electrochemical detector (conductivity mode), a Dionex AMMS-1 anion micromembrane suppressor, and a Dionex ACI advanced computer interface coupled with AI-450 chromatographic software was employed. The separation was achieved by using a Dionex IonPac AS4A-SC column as analytical column, sodium tetraborate solution as eluent, and sulfuric acid solution as regenerant. For reducing run time, a gradient program was chosen. The detection limits (S/N = 3, expressed as germanium) for the three compounds were 0.038mg/L (I), 0.035mg/L (II) and 0.025mg/L (III), respectively. The method has been applied to the analysis of two tonic oral drinks, and the average recoveries for the three compounds ranged from 95%-101%. The results obtained were in agreement with those of hydride generation atomic fluorescence spectrometry (HG-AFS).