Microsatellite instability(MSI) in non-small cell lung cancer(NSCLC) is highly associated with transforming growth factor-beta type II receptor(TGF-beta RII) frameshift mutation

BACKGROUND

TGF-beta type II receptor (TGF-beta RII) mutations associated with microsatellite instability(MSI) are characteristically frameshift mutations within a 10 bp poly-A tract. These frameshift mutations have been reported to be common in colorectal and gastric cancers with MSI, though, rarely reported in non-small cell lung cancer (NSCLC).

MATERIALS AND METHOD

In this study, we analysed MSI and TGF-beta RII frameshift mutations in 7 NSCLC cell lines and 21 surgically resected NSCLC tissues. Determination of MSI in NSCLC was performed using primer sets for BAT-25, BAT-26 and BAT-40. In order to examine the presence of the frameshift mutations of TGF-beta RII in samples with MSI, sequencing for TGF-beta RII poly-A tract was performed.

RESULTS

MSI was observed in 5 out of 7 NSCLC cell lines and 3 out of 21 NSCLC tissues. Six out of 8 samples with MSI(75%) showed frameshift mutations in TGF-beta RII poly-A tract.

CONCLUSION

These results suggest that MSI is highly associated with TGF-beta RII frameshift mutations in NSCLC and further support the hypothesis that TGF-beta RII plays an important role in NSCLC carcinogenesis.

Haloaniline-induced in vitro nephrotoxicity: effects of 4-haloanilines and 3,5-dihaloanilines

Haloanilines are widely used as chemical intermediates in the manufacture of pesticides, dyes and drugs. The purpose of this study was to examine the in vitro nephrotoxic effects of the four 4-haloaniline and four 3,5-dihaloaniline isomers using renal cortical slices obtained from the kidneys of untreated, male Fischer 344 rats. Renal cortical slices were incubated with a haloaniline hydrochloride (0.1, 0.5, 1.0 or 2.0 mM, final concentration) or vehicle for 2 h, and toxicity determined by monitoring lactate dehydrogenase (LDH) release and changes in tissue gluconeogenesis capacity. At the concentrations tested, none of the 4-haloanilines increased LDH release. 4-Bromoaniline reduced gluconeogenesis at the lowest concentration (0.1 mM), but 4-iodoaniline 2.0 mM induced the largest decrease in gluconeogenesis (92% downward arrow). Among the 3,5-dihaloanilines, 3,5-dibromoaniline proved to be the most potent nephrotoxicant and 3,5-difluoroaniline the least potent nephrotoxicant. LDH release was increased by the dibromo (1.0 and 2. 0 mM), dichloro (2.0 mM) and diiodo (2.0 mM) derivatives, but not by 3,5-difluoroaniline. These results demonstrate that 3, 5-dihaloanilines are generally more potent nephrotoxicants in vitro than the 4-haloaniline isomers, and that bromo and iodo substitutions enhanced the nephrotoxic potential of aniline to the greatest degree.

Increased urinary albumin excretion in Cushing's syndrome: remission after correction of hypercortisolaemia

OBJECTIVES

Increased urinary albumin excretion (UAE) in diabetic and nondiabetic subjects is frequently associated with insulin resistance syndrome and central obesity. Cushing's syndrome is also characterized by central obesity and insulin resistance. This study was undertaken to see whether increased UAE is found in Cushing's syndrome.

DESIGN

Cross-sectional study.

PATIENTS

Thirteen consecutive patients with Cushing's syndrome.

MEASUREMENTS

Patients collected three overnight urine samples for the measurement of UAE by radioimmunoassay. UAE was also measured in 479 nondiabetic subjects who comprised the control population for this study. In the patients who had initial microalbuminuria, UAE was remeasured 2 months after successful removal of pituitary or adrenal tumours. Kidney biopsy was performed in three patients during adrenalectomy.

RESULTS

Eleven out of 13 patients (84.6%) had increased UAE (> 9.6 micrograms/min), and eight patients (61.5%) had microalbuminuria or overt proteinuria (> 20 micrograms/min). Kidney biopsy revealed apparently normal glomerular structures without evidence of diabetic nephropathy. After correction of hypercortisolaemia, UAE declined profoundly in all of the patients.

CONCLUSIONS

More than 80% of patients with Cushing's syndrome had increased UAE. This was almost completely reversed after successful treatment of hypercortisolaemia. These results indicate that endogenous hypercortisolaemia increases UAE by a mechanism that is presently unknown.

Spontaneous programmed cell death of peripheral blood mononuclear cells from HIV-infected persons is decreased with interleukin-15

Interleukin 15 (IL-15) is an important regulatory cytokine in cellular immunity. In vitro replacement of IL-15 has been shown to enhance immunity in Human immunodeficiency virus type 1 (HIV-1) infected lymphocytes. We evaluated the effect of IL-15 on the survival of peripheral blood mononuclear cells of HIV patients by examining in vitro lymphocyte apoptosis, and correlated the process with Bcl-2 and Fas gene regulation. Peripheral blood mononuclear cells (PBMC) from 21 HIV-infected adults and 24 HIV-seronegative healthy individuals were isolated and cultured to determine the effect of escalating doses of IL-15 (0, 1, 10, 100, 1000 ng/mL) on apoptosis. Lymphocyte proliferation assay with (3H) TdR was measured and Bcl-2 and Fas gene regulation was observed. The results were as follows: 1) IL-15 reduced culture induced lymphocyte apoptosis in HIV patients in a dose dependent manner, and reached a plateau level at a concentration of 100 ng/ml; 2) IL-15 significantly reduced the level of apoptosis after 3 days (14%) and 5 days (15%) of culture in HIV patients, while no difference was observed in HIV (-) donors; 3) The percentage of viable cells among the total number of lymphocytes was significantly enhanced by 25% in HIV patients with IL-15; 4) Bcl-2 expression was decreased in HIV patients (53.9 +/- 12.3%) compared to HIV (-) donors (93.0 +/- 3.7%), and IL-15 increased Bcl-2 expression by 21.2 +/- 5.2% in HIV patients; 5) Fas expression was increased in HIV patients (70.2 +/- 4.6%) compared to HIV (-) donors (32.4 +/- 4.3%), and IL-15 increased Fas expression by 8.4 +/- 1.2% in HIV (-) donors. Our findings indicate that IL-15 may influence immunologic abnormalities in HIV infection, particularly its ability to prevent apoptosis of lymphocytes by suppressing the down-modulation of Bcl-2. This may provide an experimental basis for IL-15 immunotherapy.

Structural comparison of zebrafish Elav/Hu and their differential expressions during neurogenesis

The present communication reports the isolation and characterization of three new zebrafish elav/Hu (Kim, C.-H., Ueshima, E., Muraoka, O., Tanaka, H., Yeo, S.-Y., Huh, T.-L. and Miki, N., Zebrafish elav/HuC homologue as a very early neuronal marker. Neurosci. Lett., 216 (1996) 109-112) homologues, HuA, HuD and HuG. While HuA and HuG showed weak and ubiquitous expressions, HuD, as well as HuC, were specifically expressed in the neuronal cells. The first expression of HuD was detectable of the 10-somite stage, that is, several hours later than HuC. After 24 h of embryonic development, although HuD and HuC expressions overlapped overall, the cells expressing HuD were restricted to subsets of the HuC-positive neuronal cells in the brain and spinal cord. These differentially regulated spatial and temporal expression patterns implied distinct roles for HuC and HuD in neuronal determination and neuronal differentiation, respectively.

Suppression of endogenous insulin secretion by exogenous insulin in patients with insulinoma

OBJECTIVE

Previous studies have demonstrated that endogenous insulin secretion is not suppressed by exogenous insulin in patients with insulinoma. In this study we examined whether insulin secretion in insulinoma patients is suppressed by exogenous insulin during hypoglycaemia.

SUBJECTS AND METHODS

Sixteen insulinoma patients (5 men and 11 women) and 10 normal subjects were studied. Hyperinsulinaemic glucose clamp studies were performed at both euglycaemia (4.5 mmol/l glucose) and hypoglycaemia (2.5 mmol/l glucose).

RESULTS

In normal subjects, plasma C-peptide levels were suppressed by 66% during the euglycaemic hyperinsulinaemic clamps (P < 0.01). In contrast, in insulinoma patients, plasma C-peptide levels increased by 25% during the clamps (P < 0.05). In the hypoglycaemic hyperinsulinaemic clamps, plasma C-peptide levels were nearly completely (91%) suppressed in normal subjects and partially (39%) suppressed in patients with insulinoma (P < 0.01). The decrease in C-peptide levels during the hypoglycaemic clamps was > 30% in 12 (75%) of 16 insulinoma patients and > 50% in 8 (50%) patients.

CONCLUSIONS

This study demonstrated that in patients with insulinoma, insulin secretion was not suppressed by exogenous insulin during euglycaemia but was suppressed during hypoglycaemia, although the degree of suppression was less than that in normal subjects. Our results suggest that the feedback regulation of insulin secretion by exogenous insulin is partially retained in patients with insulinoma.

Changes in nerve growth factor levels in dorsal root ganglia and spinal nerves in a rat neuropathic pain model

The purpose of this study was to measure the changes in levels of nerve growth factor (NGF) in dorsal root ganglia (DRG) and spinal nerves with the aim of investigating the role of NGF in a rat neuropathic pain model. Nerve injuries were made by tight ligation of the left L5 and L6 spinal nerves using 6-0 silk thread in male Sprague-Dawley rats. Before surgery and 1, 3, 5, 7, and 14 days after surgery, tissue samples collected included the L3-6 DRGs bilaterally, segments of the ipsilateral L5-6 spinal nerves proximal and distal to ligation sites, and corresponding sites of the contralateral L3-6 and the ipsilateral L3-4 spinal nerves. NGF levels in the DRGs of the injured spinal nerves (the left L5 and L6) did not change significantly from control values. The spinal nerve segments distal to ligation sites had higher levels of NGF than the control values. Unlesioned sites did not show any significant changes in NGF levels. The increase of NGF in distal segments of injured spinal nerves may be due to an accumulation of retrogradely transported NGF. The maintenance of NGF levels in the DRGs that had lost peripheral connections may reflect local synthesis after nerve injury.

Sodium sulfate potentiates N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA) nephrotoxicity in the Fischer 344 rat

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) induces nephrotoxicity as its major toxicity in rats. Previous studies have shown that NDPS induces nephrotoxicity following oxidation of the succinimide ring to form N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and the hydrolysis product of NDHS, N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA). Our recent work found that sodium sulfate potentiated NDPS nephrotoxicity, suggesting that sulfate conjugation of NDPS metabolites might be a bioactivation step mediating NDPS nephrotoxicity. The purpose of this study was to determine if sodium sulfate also potentiated the nephrotoxicity of the two nephrotoxic metabolites of NDPS and further to see if sodium sulfate potentiated NDHS and 2-NDHSA nephrotoxicity to the same degree. Male Fischer 344 rats (4-16 rats/group) received an intraperitoneal (ip) injection of sodium sulfate (10 mg/kg) 20 min before a non-nephrotoxic dose (0.05 mmol/kg, ip) of NDHS or 2-NDHSA, or vehicle (12.5% dimethyl sulfoxide in sesame oil). Renal function was then monitored over 48 h. Sodium sulfate pretreatment potentiated the renal effects of a non-nephrotoxic dose of NDHS and 2-NDHSA to induce nephrotoxicity. Nephrotoxicity was characterized by diuresis, increased proteinuria, elevated blood urea nitrogen (BUN) concentration, increased kidney weight and proximal tubular necrosis. Differences in the potentiation of NDHS and 2-NDHSA nephrotoxicity by sodium sulfate were also observed as NDHS nephrotoxicity was potentiated to a lesser degree than 2-NDHSA-induced nephrotoxicity. These results support the likelihood that one or more sulfate conjugate(s) of NDPS metabolites contribute to NDPS nephrotoxicity.

2-Amino-5-chlorophenol toxicity in renal cortical slices from Fischer 344 rats: effect of antioxidants and sulfhydryl agents

2-Amino-5-chlorophenol is nephrotoxic through an unidentified mechanism. This study examined the in vitro toxicity of 2-amino-5-chlorophenol in renal cortical slices from Fischer 344 rats and specifically assessed induction of lipid peroxidation and depletion of renal glutathione. Renal cortical slices exposed to 0, 0.25, 0.5, and 1 mM 2-amino-5-chlorophenol exhibited a concentration- and time-dependent increase in lactate dehydrogenase (LDH) leakage. Pyruvate-directed gluconeogenesis was diminished in a concentration-dependent manner following a 90-min incubation with 0, 0.25, 0.5, and 1 mM 2-amino-5-chlorophenol. Lipid peroxidation was induced within 60 min by 1 mM 2-amino-5-chlorophenol in renal slices relative to control tissue. Total glutathione (GSH) levels were decreased below control values within 30 min of exposure to 0.5 and 1 mM 2-amino-5-chlorophenol. These results indicated that GSH levels were decreased prior to the appearance of increased LDH leakage and diminished membrane integrity. 2-Amino-5-chlorophenol toxicity was increased in renal slices isolated from animals pretreated with buthionine sulfoximine (BSO, 890 mg/kg ip). Pretreatment of renal slices with the phenolic antioxidant N,N'-diphenyl-1, 4-phenylenediamine (DPPD, 50 microM) or the iron chelator deferoxamine did not reduce 2-amino-5-chlorophenol cytotoxicity. These results suggest that 2-amino-5-chlorophenol toxicity was not mediated through an iron-dependent mechanism. 2-Amino-5-chlorophenol cytotoxicity was reduced by a 15-min pre-incubation with 2 mM ascorbate or a 30-min preincubation with the thiol-containing agents GSH (1 mM) or dithiothreitol (1 mM, DTT). Pretreatment with GSH, DTT, or ascorbate reduced LDH leakage and lipid peroxide generation induced by 2-amino-5-chlorophenol. These results suggest that 2-amino-5-chlorophenol cytotoxicity involved free radical generation through an iron-independent mechanism. Toxicity was reduced by the presence of the antioxidant ascorbate or by addition of glutathione.

Localization of calcium-binding protein parvalbumin-immunoreactive neurons in mouse and hamster visual cortex

Calcium-binding proteins are thought to play important roles in regulating intracellular calcium in the central nervous system. In the present study, we investigated the distribution and morphology of neurons containing parvalbumin in the visual cortex of mouse and hamster. The calcium-binding proteins were localized using immunocytochemistry. Parvalbumin-immunoreactive neurons were located in all layers except layer I. The highest density of parvalbumin immunoreactivity was found in layer V of both mouse and hamster. The labeled neurons varied in morphology. The majority of the parvalbumin-immunoreactive neurons both in mouse and hamster visual cortex was stellate and round, or oval with multipolar dendrites. These results indicate that the calcium-binding protein parvalbumin is contained in specific layers and in selective cell types of the mouse and hamster visual cortex. The distribution of parvalbumin in the mouse visual cortex is very similar to that of hamster.

Electrophysiological evidence for the role of substance P in retinohypothalamic transmission in the rat

The retinohypothalamic tract (RHT) is a neural pathway through which photic time cues are delivered directly to the mammalian circadian pacemaker in the suprachiasmatic nucleus (SCN). Although the excitatory amino acid glutamate is the primary neurotransmitter in the RHT, other substances such as substance P (SPq also have been suggested to play a role. The present study tested the hypothesis that SP participates in retinohypothalamic transmission and selectively modulates either N-methyl-D-aspartate (NMDA) or non-NMDA receptor-mediated neurotransmission. The SP antagonist L-703,606 depressed the excitatory postsynaptic current (EPSC) evoked by optic nerve stimulation in SCN neurons in rat hypothalamic slices. The SP antagonist also had a similar depressive effect on the NMDA and non-NMDA receptor-mediated components of the EPSC. These results suggest that SP is an excitatory neuromodulator contributing to the expression of both the NMDA and non-NMDA receptor-mediated components of retinohypothalamic transmission.

Multicentric juvenile pilocytic astrocytoma occurring primarily in the trigone of the lateral ventricle

The authors report a juvenile pilocytic astrocytoma (JPA) in the trigone of an 11-year-old girl, apparently with disseminated lesions that disappeared spontaneously after the removal of primary lesion. Gadolinium-enhanced magnetic resonance images (MRIs) showed features suggestive of the development of multicentric spread of the tumor at the initial diagnosis. Histologically the primary tumor showed the typical features of a JPA. Serial postoperative MRIs demonstrated that everything except a remnant of the primary tumor seemed to regress spontaneously without any adjuvant therapy. The site of origin of this tumor is thought to be the subependymal glia of the occipital lobe.

Increased expression of IL-4, IL-5, IFN-gamma, IL-6, IL-8, and TGF-beta mRNAs in maxillary mucosa of patients with chronic sinusitis

This study aimed to investigate expression of various cytokine mRNAs, including IL-6, IL-8, TGF-beta, IL-4, IL-5, and IFN-gamma in maxillary sinus mucosa of patients with chronic sinusitis. Maxillary sinus mucosae of six patients with chronic sinusitis and turbinate mucosae of six healthy subjects were obtained. We performed RT-PCR and Southern blot to examine gene expression of the cytokines IL-6, IL-8, TGF-beta, IL-4, IL-5, and IFN-gamma in maxillary sinus mucosa and compared the results with cytokine gene expressions in normal turbinate mucosa. IL-6, IL-8, TGF-beta, IL-4, IL-5, and IFN-gamma mRNAs were expressed more frequently in maxillary sinus mucosa from patients with chronic sinusitis than in normal turbinate mucosa. All the maxillary sinus mucosa specimens revealed relatively higher mean density ratio for each cytokine investigated than did normal turbinate mucosa. IL-6, IL-8, TGF-beta, IL-4, IL-5, and IFN-gamma mRNAs were expressed simultaneously in maxillary sinus mucosa of chronic sinusitis. These cytokines may be responsible for recruitment of inflammatory cells and for mucosal thickening in chronic sinusitis, and thus chronicity of the disease.

Initiation of shoot apical meristem in rice: characterization of four SHOOTLESS genes

The regulatory mechanism of shoot apical meristem (SAM) initiation is an important subject in developmental plant biology. We characterized nine recessive mutations derived from four independent loci (SHL1-SHL4) causing the deletion of the SAM. Radicles were produced in these mutant embryos. Concomitant with the loss of SAM, two embryo-specific organs, coleoptile and epiblast, were lost, but the scutellum was formed normally. Therefore, differentiation of radicle and scutellum is regulated independently of SAM, but that of coleoptile and epiblast may depend on SAM. Regeneration experiments using adventitious shoots from the scutellum-derived calli showed that no adventitious shoots were regenerated in any shl mutant. However, small adventitious leaves were observed in both mutant and wild-type calli, but they soon became necrotic and showed no extensive growth. Thus, leaf primordia can initiate in the absence of SAM, but their extensive growth requires the SAM. An in situ hybridization experiment using a rice homeobox gene, OSH1, as a probe revealed that shl1 and shl2 modified the expression domain of OSH1, but normal expression of OSH1 was observed in shl3 and shl4 embryos. Accordingly, SHL1 and SHL2 function upstream of OSH1, and SHL3 and SHL4 downstream or independently of OSH1. These shl mutants are useful for elucidating the genetic program driving SAM initiation and for unraveling the interrelationships among various organs in grass embryos.

Is sympathetic sprouting in the dorsal root ganglia responsible for the production of neuropathic pain in a rat model?

Partial peripheral nerve injury often results in neuropathic pain that is aggravated by sympathetic excitation and induces sympathetic nerve sprouting in both the injured nerve and corresponding dorsal root ganglia (DRGs). Presently, the functional mechanisms of the interactions between the sprouting and injured somatic afferents remain uncertain. This study was performed to see whether the sprouting in the DRGs plays a key role in the development of neuropathic pain. To this aim, we compared two groups of rats, both of which were subjected to unilateral transection of the superior and inferior caudal trunks at the level between the S1 and S2 spinal nerves, with respect to sympathetic fiber sprouting; one group showed well-developed neuropathic pain behaviors (i.e. mechanical, cold and warm allodynia signs) and the other group showed poorly-developed ones. Immuno-histochemical staining with tyrosine hydroxylase (TH) antibody of the injured S1 DRG taken from both groups of rats after behavioral tests revealed that the magnitude of penetration of TH-positive fibers into the S1 DRG was not significantly different between the two groups. These results suggest that sympathetic nerve sprouting in the injured DRG is not a key factor in the development of neuropathic pain.

Some membrane property changes following axotomy in A delta-type DRG cells are related to cold allodynia in rat

Numerous studies have suggested that changes in electrophysiological properties of primary sensory neurons after axonal injury contribute to the generation of neuropathic pain. Presently, however, it is unclear which of the changes is important. To address this issue, we performed behavioral and electrophysiological experiments in a double-blind fashion; we made intracellular recordings in the S1 dorsal root ganglia excised from rats exhibiting cold allodynia behavior after chronic S1 spinal nerve transaction (allodynia-positive group) and from rats lacking such behavior after the same nerve injury (allodynia-negative group) or sham injury (sham group). In this study, we sought which of the membrane property changes produced by the spinal nerve injury in each of C-, Adelta- and Aalpha/beta-cell populations was unique to the allodynia-positive group. Analyses of our data revealed that only some changes in Adelta-cells (e.g. the decrease in resting membrane potential and in the threshold of central process) were more pronounced in or unique to the allodynia-positive group. We concluded that certain membrane property changes in the somata and dorsal root axons of Adelta-cells might be important in the generation of cold allodynia.

Effect of sulfation substrates/inhibitors on N-(3,5-dichlorophenyl)succinimide nephrotoxocity in Fischer 344 rats

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is an acute nephrotoxicant in rats. Our previous studies suggested that sulfate conjugation of NDPS metabolites might be a bioactivation step mediating NDPS nephrotoxicity. In this study, effects of substrates and/or inhibitors of sulfation on NDPS nephrotoxicity were examined to explore further the role of sulfation in NDPS nephrotoxicity. Male Fischer rats (4-8/group) were administered one of the following intraperitoneal (ip) pretreatment (dose, pretreatment time) prior to NDPS (0.6 mmol/kg) or NDPS vehicle (sesame oil, 2.5 ml/kg): (1) no pretreatment, (2) dehydroepiandrosterone (DHEA) (0.5 mmol/kg, 1 h), or (3) 2,6-dichloro-4-nitrophenol (DCNP) (0.04 mmol/kg, 1 h). Following NDPS or NDPS vehicle administration, renal function was monitored at 24 and 48 h. Pretreatment with DHEA, a typical substrate for and an inhibitor of hydroxysteroid (alcohol) sulfotransferase, resulted in marked protection against NDPS nephrotoxicity. A selective inhibitor of phenol sulfotransferase, DCNP, afforded little attenuation in NDPS nephrotoxicity. These results suggest that alcohol sulfate conjugates of NDPS metabolites, rather than phenolic sulfate conjugates, may be a penultimate or ultimate nephrotoxicant species mediating NDPS nephrotoxicity. The marked, but not complete, protection by DHEA also suggests that there are other metabolites or mechanisms responsible for NDPS nephrotoxicity.

Elevated plasma proinsulin/insulin ratio is a marker of reduced insulin secretory capacity in healthy young men

AIM

To examine whether reduced insulin secretory capacity or increased insulin secretory demand is associated with elevated ratio of plasma proinsulin to immunoreactive insulin (PI/IRI ratio) in non-diabetic subjects.

SUBJECTS AND METHODS

We measured various indices of insulin secretory function and insulin sensitivity by frequently sampled intravenous glucose tolerance test (FSIGT) and hyerglycemic glucose clamp in 21 healthy young men. We then examined the relationships between these indices and PI, IRI, or PI/IRI ratio in the fasting state.

RESULTS

Insulin sensitivity index (SI) measured by FSIGT correlated inversely with basal IRI (r=-0.53, P < 0.01) and PI levels (r=-0.57, P < 0.01), but there was no significant correlation between SI and PI/IRI ratio (r=0.26, NS). On the other hand, PI/IRI ratio correlated inversely with insulin secretory indices, such as acute insulin responses during FSIGT (r =-0.46, P < 0.01) and hyperglycemic glucose clamp (r=-0.54, P < 0.01) and submaximum insulin response during hyperglycemic glucose clamp (r=-0.59, P < 0.01).

CONCLUSIONS

These results indicate that elevated PI/IRI ratio may serve as a marker of reduced insulin secretory function in non-diabetic subjects.

Nephrotoxic potential of N-(3,5-dichloro-4-fluorophenyl)succinimide in Fischer 344 rats: comparison with N-(3,4,5-trichlorophenyl)succinimide

Numerous structure-nephrotoxicity relationship studies from our laboratory have demonstrated that N-(3,5-dichlorophenyl)succinimide (NDPS) is one of the most potent nephrotoxicants among the N-arylsuccinimides. The purpose of this study was to extend our previous structure-nephrotoxicity relationship studies by examining the effect of addition of a fluoro verses a chloro group at the 4-phenyl position in NDPS. Male Fischer 344 rats (four rats/group) received a single intraperitoneal (i.p.) injection of N-(3,5-dichloro-4-fluorophenyl)succinimide (NDCFPS) or N-(3,4,5-trichlorophenyl)succinimide (NTCPS)(0.4 or 0.8 mmol/kg) or vehicle, and renal function monitored at 24 and 48 h. NDCFPS did not induce significant nephrotoxicity at either dose tested. In contrast, NTCPS (0.4 or 0.8 mmol/kg) induced marked nephrotoxicity characterized by diuresis, increased proteinuria, glucosuria, elevated kidney weight and increased blood urea nitrogen (BUN) concentration. NTCPS also induced marked proximal tubular necrosis at both doses tested. Neither NDCFPS nor NTCPS induced hepatotoxicity at either dose tested. The results of these experiments indicate that addition of a fluoro group at the 4-position on the phenyl ring of NDPS produces a nonnephrotoxicant NDPS derivative (NDCFPS), while addition of a chloro group at this site produces an NDPS derivative with similar nephrotoxic potential to NDPS. The mechanism for this differential effect between 4-halophenyl substitution is unclear, but may result from increased hydrolysis of the succinimide ring and/or increased clearance of N-arylsuccinimide metabolites when a fluoro group is added to the 4-position of the phenyl ring.

SHC1, a high pH inducible gene required for growth at alkaline pH in Saccharomyces cerevisiae

In this study, we carried out a large-scale transposon tagging screening to identify genes whose expression is regulated by ambient pH. Of 35,000 transformants, two strains carrying the genes whose expression is strictly dependent on pH of growth medium were identified. One of the genes with 20-fold induction by alkali pH was identified as SHC1 gene in the Yeast Genome Directory and its expression was the highest at alkaline pH and moderately induced by osmotic stress. However, the gene was expressed neither at acidic pH nor by other stress conditions. The haploid mutant with truncated shc1 gene showed growth retardation and an abnormal morphology at alkaline pH. On the other hand, the mutant strain carrying the wild-type SHC1 gene reverted to the mutant phenotype. To confirm that Shc1p is an alkali-inducible protein, a monoclonal antibody to Shc1p was produced. While a 55-kDa protein band appeared on the Western blot of cells grown at alkaline pH, Shc1p was barely detectable on the blots of cells grown in YPD. Our results indicate that yeast cells have an efficient system adapting to large variations in ambient pH and SHC1 is one of the genes required for the growth at alkaline pH.

The role of glucuronidation in N-(3,5-dichlorophenyl)succinimide (NDPS) nephrotoxicity: nephrotoxic potential of NDPS and NDPS metabolites in Gunn, Wistar, and Fischer 344 rats

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is an acute nephrotoxicant in rats. Although the mechanism of NDPS nephrotoxicity is not clear, our previous studies have strongly suggested that glucuronide conjugation of NDPS metabolite(s) is an important biotransformation reaction leading to the ultimate nephrotoxicant metabolite(s) mediating NDPS nephrotoxicity. In this study, the nephrotoxic potential of NDPS and its nephrotoxicant metabolites, N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (NDHSA), was examined in Gunn rats, which contain a genetic deficiency in bilirubin uridine diphosphate-glucuronosyltransferase (UDPGT), to explore further the role of glucuronidation in NDPS nephrotoxicity. The nephrotoxic potential of NDPS, NDHS, and NDHSA was also examined in Wistar rats, the parent strain for Gunn rats and which generally have normal UDPGT activity. Comparisons were then made with the nephrotoxicity induced by these compounds in Fischer 344 (F344) rats. Age-matched male F344, homozygous (j/j) Gunn, and Wistar rats were used. Rats (four to eight rats/group) of each strain were administered NDPS (0.4 mmol/kg ip), NDHS (0.1 or 0.2 mmol/kg ip), NDHSA (0.1 mmol/kg ip), or vehicle, and renal effects were monitored functionally and morphologically for 48 h. NDPS and its nephrotoxicant metabolites, NDHS and NDHSA, were much weaker nephrotoxicants in Gunn rats than in F344 rats, while Wistar rats were susceptible to the nephrotoxicity induced by NDPS, NDHS, or NDHSA. These results suggest that the lack of NDPS nephrotoxicity observed in Gunn rats is due to the deficiency in UDPGT in this strain rather than the parent Wistar strain being inherently nonresponsive to NDPS nephrotoxicity. Therefore, it appears that glucuronide metabolite(s) of NDHS and/or NDHSA contribute(s) to NDPS nephrotoxicity, although the exact nature of the nephrotoxicant glucuronide metabolite(s) of NDPS remains to be determined.

Effect of glucuronidation substrates/inhibitors on N-(3,5-dichlorophenyl)succinimide nephrotoxicity in Fischer 344 rats

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is an acute nephrotoxicant in rats. Our previous studies have strongly suggested that glucuronide conjugation of NDPS metabolites might be a bioactivation step mediating NDPS nephrotoxicity. In this study, effects of substrates and/or inhibitors of primarily glucuronidation on NDPS nephrotoxicity were examined to explore further the role of glucuronidation in NDPS nephrotoxicity. Male Fischer 344 rats (4-6/group) were administered one of the following intraperitoneal (i.p.) pretreatments (dose, pretreatment time) prior to NDPS (0.4 mmol/kg) or NDPS vehicle (sesame oil, 2.5 ml/kg): (1) no pretreatment; (2) borneol (900 mg/kg, 30 min); (3) eugenol (500 mg/kg per day, 3 days); (4) clofibric acid (400 mg/kg, 15 min before (1/2 dose) and 3 h after (1/2 dose)), or (5) valproic acid, sodium salt (1.0 mmol/kg, 15 min). Following NDPS or NDPS vehicle administration, renal function was monitored at 24 and 48 h. Pretreatment with borneol or eugenol, substrates for ether glucuronidation and sulfation (mainly glucuronidation), afforded complete protection against NDPS nephrotoxicity. Substrates for acyl glucuronidation, clofibric acid or valproic acid, mildly reduced or had little effect on NDPS nephrotoxicity, respectively. These results suggest that ether glucuronide conjugates of NDPS metabolites, rather than acyl glucuronide conjugates, may be the primary ultimate nephrotoxicant species mediating NDPS nephrotoxicity.

Effects of IL-1 beta, TNF-alpha, and TGF-beta on ciliary beat frequency of human nasal ciliated epithelial cells in vitro

Previous reports suggested that several cytokines may influence the ciliary beat of the airway ciliated epithelial cells. The aim of this study is to determine the effects of cytokines including IL-1 beta, TNF-alpha, and TGF-beta on ciliary beat frequency (CBF) of human nasal ciliated epithelial cells. CBF of cultured human nasal ciliated epithelial cells was measured 24 hours after incubating with concentrations of 0.01 ng/mL, 0.1 ng/mL, 1 ng/mL, 10 ng/mL, and 100 ng/mL of each recombinant human (rh) cytokine including rhIL-1 beta, rhTNF-alpha, and rhTGF-beta. CBF was measured with time at concentrations of 1 ng/mL of rhIL-1 beta, 10 ng/mL of TNF-alpha, and 1 ng/mL of TGF-beta solutions. CBF of the human nasal ciliated epithelial cells increased after addition of rhIL-1 beta and rhTNF-alpha. Maximum CBF was observed at 1 ng/mL of rhIL-1 beta and at 10 ng/mL of rhTNF-alpha. CBF increased progressively to 4 hours after addition of rhIL-1 beta and rhTNF-alpha. Increased CBF sustained for 24 hours and decreased by 2 days. However, no variation of CBF was observed after addition of rhTGF-beta, regardless of concentrations and time. The results of this study suggest that during acute inflammation, IL-1 beta and TNF-alpha may have a potential role in defense mechanism of human nasal epithelium by regulating CBF of the nasal ciliated epithelial cells.

High serum lipoprotein(a) levels in Korean type 2 diabetic patients with proliferative diabetic retinopathy

OBJECTIVE

To examine the possible association between serum lipoprotein(a) [Lp(a)] concentration and proliferative diabetic retinopathy (PDR) in Korean patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 412 Korean outpatients with type 2 diabetes were examined. Diabetic retinopathy was determined by an ophthalmologist using fundoscopic examination. Serum Lp(a) levels were measured by two-site sandwich enzyme-linked immunosorbent assay.

RESULTS

The patients with PDR had higher serum Lp(a) levels than those with no diabetic retinopathy or with nonproliferative diabetic retinopathy (NPDR). Multiple logistic regression analysis showed that high serum Lp(a) levels and the presence of diabetic nephropathy were independent variables having a statistically significant association with PDR.

CONCLUSIONS

Korean type 2 diabetic patients with PDR had higher serum Lp(a) levels versus those with no diabetic retinopathy or with NPDR. Although these results suggest that Lp(a) might play a role in the occlusion of retinal capillaries leading to PDR, further prospective studies are required to prove the causal relationship.