Purification and characterization of an 82-kD membrane protein as a neurite outgrowth factor binding protein: possible involvement of NOF binding protein in axonal outgrowth in developing retina

Neurite outgrowth factor (NOF) is a glycoprotein isolated from an extract of gizzard that induces neurite outgrowth from cultured retinal or ciliary ganglionic (CG) neurons. We have reported that a glycoprotein of approximately 82 kD solubilized from gizzard muscles binds to NOF (ligand blotting) and inhibits the neurite promoting activity of NOF (inhibition assay). The 82-kD protein (NOF binding protein) was purified from gizzard muscle membranes as a doublet band on SDS-PAGE and a polyclonal antibody was raised against it. An NOF binding protein in developing retina exhibited the same physicochemical properties as that of the gizzard muscle. Quantitative decrease in NOF binding protein in embryonic retinas was observed after day 11 by the inhibition assay, ligand blotting, and immunoblotting, its decrease being parallel with reduction of NOF-induced neurite outgrowth of embryonic retinas. In an immunohistochemical study, the antibody stained only the optic fiber layers of the retinas of 8-d embryos, and this staining was no longer detectable in retinas of 18-d embryos. These results suggest that the 82-kD protein is a novel membrane protein that behaves as an NOF receptor and that the loss of neuritic response of the retinal neurons to NOF reflects a decrease in NOF receptor molecules.

Upper gastrointestinal bleeding in dengue fever

Twenty-six virologically and serologically confirmed Dengue patients with signs of upper gastrointestinal tract bleeding (13.1%) were studied during the 1987 outbreak in southern Taiwan. Within a 1-yr period from 1987 to 1988 in Kaohsiung Chang Gung Memorial Hospital, there were 198 patients with Dengue fever confirmed. Viral isolation and serological studies indicated that type I Dengue was the cause. There was no evidence of sequential secondary infection among them. The 26 patients were evaluated gastroduodenoscopically. Most of the Dengue patients who developed upper gastrointestinal bleeding had gastric ulcers or duodenal ulcers; superficial and hemorrhagic gastritis are the other relevant endoscopic findings. Thirteen patients (50%) had a past history of peptic ulcer symptoms, whereas the other 13 did not. Dengue infection is a precipitating factor in inducing peptic ulcer bleeding because of hemostatic derangements. Supportive therapy and blood transfusions alone were adequate treatment, except for one patient who required surgery due to massive bleeding of a duodenal ulcer. No mortality was observed in this study.

Retroperitoneal neurilemoma: clinical features in 10 cases

Neurilemoma is a rare tumor in the retroperitoneal cavity. Up to 1984, less than 50 cases had been reported in the English literature. We observed 10 cases of retroperitoneal neurilemoma with histologic proof at our hospital. The major symptoms were abdominal pain (80%) and body weight loss (40%). Physically palpable abdominal masses were found in 90% of the cases. The laboratory data were all within normal limits, except for a mild elevation of the eosinophil count in 4 cases. Radiologic examination demonstrated the tumor in most cases. Abdominal ultrasonography was very effective in the detection of these tumors. Surgical resection was the treatment of choice. Some patients suffered from leg numbness after the operation. Recurrent rate was high, up to 20% therefore, long-term follow-up is mandatory.

Isolation and analysis of the human MEKA gene encoding a retina-specific protein

We have isolated and sequenced a human gene encoding photoreceptor cell-specific MEKA protein. The protein coding region was separated into three exons, which encoded 246 amino acid residues with a molecular weight of 28,311. The coding region of the human gene exhibited the homologies of 90.7% nucleotides and 88.5% amino acids with those of the bovine cDNA. Southern blot analysis revealed that the human MEKA gene has a single copy number. However, the anti-bovine MEKA stained both rod and cone photoreceptor cells in the human retina.

Visinin: a novel calcium binding protein expressed in retinal cone cells

Visinin is a retinal cone cell-specific protein (molecular weight 24,000, pI 5.1). To investigate its function, visinin cDNA was isolated from a chick retinal lambda gt11 cDNA library, using anti-visinin serum. The beta-galactosidase-visinin fusion protein was used for purifying epitope-selected antibody. The purified visinin antibody reacted only with a 24 kd protein in retinal cone cells. Visinin mRNA was expressed only in the retinal photoreceptor layer. The nucleotide sequence of the cDNA revealed that visinin has three E-F hand structures and is a Ca2+ binding protein. Visinin protein expressed in E. coli exhibited Ca2+ binding activity. These results suggest that visinin is a photoreceptor-specific Ca2+ binding protein and may be involved in phototransduction in the cone cells.

Developmental changes of MEKA protein and opsin in normal and rd mice

Antisera raised against photoreceptor-specific MEKA and opsin proteins were provided for immunohistochemical studies on the retinas of normal (BJ57BL/6) and retinal degeneration (rd, C3H/He) mice. The expression of MEKA protein began at postnatal day 6 (P6) in the photoreceptor cells and gradually increased until P10 in both normal and rd mice. Thereafter the MEKA proteins in the photoreceptor cells of rd mice gradually decreased and disappeared at P18, whereas those of normal mice were increasing until P18. The time course of MEKA proteins in the photoreceptor cells of normal and rd mice was almost similar to that of opsin protein, except that the MEKA protein disappeared earlier than opsin.

Identification of a retina-specific MEKA protein as a 33 K protein

A photoreceptor-specific MEKA protein was purified from bovine retinal soluble fraction. The purified sample was eluted as a single peak of 74 kDa protein from a Superose column, which was dissolved into three components, MEKA protein (32 kDa), beta-(36 kDa) and gamma-(10 kDa) subunits of transducin on a SDS-PAGE. From several lines of evidence, we concluded that MEKA protein is identical with a 33k phosphoprotein reported by Lee et al (1).

Translocation of a photoreceptor-specific MEKA protein by light

Light-or dark-adapted retinal sections from bovine chick and mouse were provided for immunohistochemistry with antiserum against a MEKA protein which is specific to photoreceptor cells. In dark-adapted retinal sections, the anti-MEKA serum heavily stained outer segments of photoreceptor cells and lightly stained inner segments. The reverse staining pattern was observed in light-adapted retinal sections. These results indicate that the translocation of MEKA protein in a photoreceptor cell is regulated by light dark.

Isolation of a novel retina-specific clone (MEKA cDNA) encoding a photoreceptor soluble protein

We have reported the isolation of clones which are candidates for retina-specific cDNAs. One of the cDNA clones, pCR-470, was further characterized. We found that mRNA corresponding to the pCR-470 was expressed only in the retina and encodes an unknown soluble protein whose molecular weight and pI are calculated to be 26,935 and 5.35, respectively. We designated it as a MEKA protein, because its amino acid sequence starts from M-E-K-A. It was found by in situ hybridization that MEKA mRNA was transcribed only in the photoreceptor cells and accumulated in the inner segments just like opsin mRNA. The MEKA cDNA was ligated with expression vector PEX 1, and a MEKA-fusion protein synthesized in E. coli was purified and used as an antigen. By the Western blot analysis anti-MEKA protein serum reacted with a soluble 32 kDa protein from bovine retina and 33 kDa for chick, but not with proteins from other tissues. Immunohistochemical study showed that anti-MEKA stained only the photoreceptor cells in bovine, chick, rat and mouse retinas.

A longitudinal study on the expression of the opsin gene in the degenerating retina of C3H/He mice

By a combination of immunohistochemistry and in situ hybridization using a 35S-labeled opsin cDNA probe, it was revealed in rd mutant C3H/He mice that opsin mRNA is not detectable in photoreceptor cells which still exhibit opsin-immunoreactivity at later stages of retinal degeneration. This indicates that the photoreceptor cells of rd mutant mice cease to express the opsin gene at earlier stages of retinal degeneration.

Presence of retina-specific proteins in the lamprey pineal complex

The pineal complex of river lamprey reacted with the antisera raised against retina specific proteins including bovine opsin, chick visinin and frog light-sensitive cyclic GMP phosphodiesterase (PDE). Immunoreactive materials stained with anti-opsin were evenly located at the outer segment of photoreceptor cells in the pineal organ and also found in the parapineal organ. Although anti-visinin stained the pineal and parapineal photoreceptor cells, the immunopositive photoreceptor cells were observed only at the lateral portion and not at the medial portion of the pineal organ. No immunoreactive materials were found in the pineal complex by the anti-PDE, whereas the anti-PDE reacted with photoreceptor cells of the retinal tissue. The data suggest that the pineal and parapineal retinas of lamprey contain opsin- and visinin-like proteins with different distribution in their photoreceptor cell layer as found in the lamprey retinal tissue.

Two types of lamprey retina photoreceptors immunoreactive to rod- or cone-specific antibodies

The localization of structures immunoreactive to antisera against opsin (OPS; a specific marker for rods) and against visinin (VIS; a specific marker for cones in the vertebrate retina) was investigated in the retina of the river lamprey (Lampetra japonica) by means of fluorescence microscopy. Different immunoreactive structures were found with the two antisera. A vitreadly located structure in the outer nuclear layer displayed OPS-like immunoreactivity, while a scleradly located one exhibited VIS-like reactivity. Thus, the two antisera applied to the retina of the river lamprey permit the distinguishing of rod and cone immunoreactive photoreceptors such as occurs typically in all vertebrate classes. The former appears in the outer segments of a type of rod cells, and the latter in the cell bodies and axons of cones.

Multiple opsin mRNA species in bovine retina

Two retina specific cDNAs have been isolated by differential colony hybridization to retina and brain, and one of them, pCR-394, was identified as an opsin cDNA. By Northern hybridization experiment, the opsin cDNA hybridized to two species of bovine mRNA, one approximately 18 S (1800 bp) and the other 22 S (2600 bp). Using pCR-394 as a probe two opsin clones, R-5 (about 1200 bp) and LR-8 (about 2500 bp), were isolated from a cDNA library which was prepared by the method of Okayama-Berg. Each had a different length of 3'-untranslated DNA. The nucleotide sequences of R-5 and LR-8, as well as Northern and Southern hybridization experiments suggest that at least two species of opsin mRNA are expressed from a single gene. When the effects of illumination were examined by Northern hybridization and translation assays, the ratio of the two opsin mRNA species was changed between light- and dark-adapted eyes.

Cloning and characterization of a cDNA specific for bovine retina

A retina-specific cDNA clone (pCR18) was selected from a bovine retinal cDNA library and characterized. The clone pCR18 consisted of 905 base pairs and hybridized to the mRNA of about 12S from the bovine retina, but not that from the brain or liver. The nucleotide sequence revealed a long open reading frame which encodes a 147 amino acid polypeptide of about 15,700 Da. No significant sequence homology with the predicted protein was found in the protein sequence library of about 3500. Messenger RNA which hybridized to pCR18 translated a polypeptide of about 19,000 Da in a reticulocyte translation system. Southern blot analysis indicated that the bovine genome contains a single copy of this gene. Furthermore, RNA dot analysis showed that the poly(A)+ RNA from the human retinoblastoma cell lines (Y79 and WERI) hybridized to pCR18, whose intensity was comparable to that of the bovine retina. In situ hybridization revealed that pCR18 was expressed mostly in some ganglion cells of the rat retina. The results suggest that cDNA clone (pCR18) encodes a protein specific for the retina and mRNA for pCR18 is mostly localized in the retinal ganglion cells and also expressed in the human retinoblastoma cells, although its function remains to be elucidated.

The role of p-aminophenol in acetaminophen-induced nephrotoxicity: effect of bis(p-nitrophenyl) phosphate on acetaminophen and p-aminophenol nephrotoxicity and metabolism in Fischer 344 rats

Acetaminophen (APAP) produces proximal tubular necrosis in Fischer 344 (F344) rats. Recently, p-aminophenol (PAP), a known potent nephrotoxicant, was identified as a metabolite of APAP in F344 rats. The purpose of this study was to determine if PAP formation is a requisite step in APAP-induced nephrotoxicity. Therefore, the effect of bis(p-nitrophenyl) phosphate (BNPP), an acylamidase inhibitor, on APAP and PAP nephrotoxicity and metabolism was determined. BNPP (1 to 8 mM) reduced APAP deacetylation and covalent binding in F344 renal cortical homogenates in a concentration-dependent manner. Pretreatment of animals with BNPP prior to APAP or PAP administration resulted in marked reduction of APAP (900 mg/kg) nephrotoxicity but not PAP nephrotoxicity. This result was not due to altered disposition of either APAP or acetylated metabolites in plasma or renal cortical and hepatic tissue. Rather, BNPP pretreatment reduced the fraction of APAP excreted as PAP by 64 and 75% after APAP doses of 750 and 900 mg/kg. BNPP did not alter the excretion of APAP or any of its non-deacetylated metabolites nor did BNPP alter excretion of PAP or its metabolites after PAP doses of 150 and 300 mg/kg. Therefore, the BNPP-induced reduction in APAP-induced nephrotoxicity appears to be due to inhibition of APAP deacetylation. It is concluded that PAP formation, in vivo, accounts, at least in part, for APAP-induced renal tubular necrosis.

Characterization of the polypeptide composition of human factor VIII:C and the nucleotide sequence and expression of the human kidney cDNA

Human coagulation factor VIII:C has been purified approximately 5000-fold from commercial preparations with an average activity yield of 35%. Proteins of 92 kD and 77-80 kD enriched during purification are precipitated by a human serum polyclonal antibody which inhibits factor VIII:C activity. Evidence suggests that these polypeptides are linked by a calcium ion bridge. Partial amino acid sequence information from these proteins has been obtained from the intact polypeptides and from products of digestion with thrombin, endoproteinase lysC, or trypsin after citraconylation. An oligonucleotide probe designed from one of the amino acid sequences was used to isolate a partial genomic clone from a human 4X chromosome library in bacteriophage lambda. The genomic segment was used to isolate two cDNA molecules encompassing the entire human kidney factor VIII:C mRNA. Biologically active factor VIII:C has been produced in a mammalian cell line utilizing a complete cDNA construction.

Effect of polybrominated biphenyls, beta-naphthoflavone and phenobarbital on arylhydrocarbon hydroxylase activities and chloroform-induced nephrotoxicity and hepatotoxicity in male C57BL/6J and DBA/2J mice

Administration of chloroform (CHCl3) to male C57/6J (C57) and DBA/2J (DBA) mice produced dose-dependent hepatic and renal damage. Hepatic arylhydrocarbon hydroxylase (AHH) activity was higher in C57 than DBA mice; in kidney, AHH activity was higher in DBA than in C57 mice. CHCl3 caused the same degree of liver damage in both strains of mice; however, nephrotoxicity of CHCl3 was greater in DBA than in C57 mice. Pretreatment of C57 and DBA mice with phenobarbital (PB) markedly increased hepatic AHH activity and hepatotoxicity of CHCl3 in both strains but did not affect renal AHH or nephrotoxicity of CHCl3. Similarly, beta-naphthoflavone (BNF) enhanced AHH activity and CHCl3 hepatotoxicity in C57 mice, but had little effect on nephrotoxicity. BNF did not affect hepatic AHH nor CHCl3-induced hepatic injury in male DBA mice. Pretreatment with polybrominated biphenyl (PBB) enhanced AHH activity in liver and CHCl3 hepatotoxicity in both strains. After PBB, nephrotoxicity of CHCl3 and renal AHH activity were increased in C57 mice whereas PBB did not alter nephrotoxicity or renal AHH in DBA mice. These results suggest that CHCl3-nephrotoxicity is independent of hepatotoxicity.

cis-Dichlorodiammineplatinum nephrotoxicity in rats of different ages

In 5-, 15-, 30-, and 60-day-old rats there was a distinct decrease of body weight 24 hours after a single i.p. injection of cis-dichlorodiammineplatinum (CDDP) over a dose range from 0.25 to 2.0 mg/100 g b.w.t. Compared with a control group the kidney weights appeared nearly unchanged. The increase of blood urea nitrogen (BUN) concentrations following CDDP treatment was dose dependent and more profound in 5- and 15-day-old rats than in older animals. In higher doses, CDDP impaired the renal concentrating ability in rats of all age groups as reflected in a significant increase in urine volume with only a slightly increased renal sodium excretion. Following CDDP treatment there was a moderate proteinuria. In 30- and 60-day-old rats the renal excretion of p-aminohippurate (PAH) was more reduced by CDDP compared to younger rats.

Nephrotoxicity of phenolic bromobenzene metabolites in the mouse

Bromobenzene, at doses greater than 5.7 mmol/kg, produced renal proximal tubular necrosis and renal functional changes in mice. p-Bromophenol and o-bromophenol were the major urinary phenolic bromobenzene metabolites although m-bromophenol and 4-bromocatechol were also excreted in detectable quantities. With the exception of o-bromophenol, urinary metabolites were excreted primarily as conjugates. 4-Bromocatechol and the 3 bromophenol isomers were nephrotoxicants (measured as increased blood urea nitrogen and decreased accumulation of organic anions by renal cortical slices) but not hepatotoxicants (measured as serum glutamic pyruvate transaminase) in vivo at 0.56 mmol/kg (i.v.). Preincubation of renal cortical slices with each of these bromobenzene metabolites for 90 min resulted in dose-dependent decreases in the accumulation of p-aminohippurate and tetraethylammonium. At 10 mumol/preincubation (2.4 mM), organic ion accumulation was decreased maximally by all bromobenzene metabolites examined while equimolar amounts of bromobenzene were without effect. 4-Bromocatechol was the most potent nephrotoxicant in vitro. Administration of 0.53-2.12 mmol/kg (i.v.) 4-bromocatechol to mice resulted in a dose-dependent decrease in renal function while hepatic function was altered only slightly at the higher doses. The renal cortical necrosis produced by in vivo administration of 4-bromocatechol could not be distinguished histologically from that induced by bromobenzene. These results demonstrate that 4-bromocatechol and the 3 bromophenol isomers are nephrotoxicants that can be generated from bromobenzene in mice.

Sex and strain differences in mouse kidney: Bowman's capsule morphology and susceptibility to chloroform

Chloroform (CHCl3) produces liver damage in male and female mice but renal injury only in male mice. Previous reports demonstrated that the parietal epithelium of Bowman's capsule in female mice is composed of squamous cells, whereas the parietal cells of Bowman's capsule from male mice consist of a mixture of squamous and cuboidal cells or purely cuboidal cells. These data suggested that the factor(s) associated with these histological differences may similarly be associated with factors that determine susceptibility to tubular damage from chloroform. The susceptibility of male mice to chloroform nephrotoxicity varies with animal strain. In the present study, administration of CHCl3 to male C57BL/6J (C57) and male and female DBA/2J (DBA) mice produced dose-dependent kidney tubular damage in male C57 and male DBA mice. However, CHCl3 nephrotoxicity was considerably greater in male DBA mice than in male C57 mice. Female DBA mice failed to develop renal damage following administration of CHCl3. Male DBA mice had a higher percentage of cuboidal parietal epithelial cells in Bowman's capsule whereas male C57 mice had a higher percentage of squamous cells in the parietal epithelium. The parietal epithelium in Bowman's capsule of female DBA mice was predominantly squamous. Since morphological differences between sex and strain of mice occurred in the capsular epithelium, and the differences in susceptibility to CHCl3 appear to be a tubular phenomenon, it is unlikely that there is a causal relationship between the structure of Bowman's capsule and chloroform-induced renal tubular necrosis; rather, these two independent phenomena are regulated by some common factor(s), possibly testosterone.

Nephrotoxicity of bromobenzene in mice

I.p. administration of bromobenzene to male mice at doses ranging from 0 to 9.4 mmol/kg resulted in a dose-dependent increase in blood urea nitrogen (BUN) and serum glutamic-pyruvic transaminase (SGPT) activity and a decrease in renal cortical accumulation of para-aminohippurate (PAH) and tetraethylammonium (TEA). Induction of renal and hepatic mixed-function oxidases by beta-naphthoflavone (BNF) did not result in any alterations in the hepatotoxic or nephrotoxic response to bromobenzene. Renal and hepatic non-protein sulfhydryl (NPSH) concentrations were decreased significantly 1 h after administration of bromobenzene (7.5 mmol/kg) and were maximally depleted in both organs to 18% of control after 7 h. Depletion of renal NPSH by bromobenzene was dose-dependent up to 9.4 mmol/kg. Treatment of mice with diethyl maleate (DEM) (0.6 ml/kg) 60 min prior to bromobenzene administration resulted in greater hepatotoxicity, evidenced by increased SGPT, while renal toxicity was unchanged. These data demonstrate that large doses of bromobenzene produce functional alterations in the kidney.

Effect of dietary trans-stilbene oxide on hepatic and renal drug-metabolizing enzyme activities and bromobenzene-induced toxicity in male Sprague-Dawley rats

The effect of dietary trans-stilbene oxide (TSO) on hepatic and renal xenobiotic metabolizing-enzyme activities and bromobenzene-induced toxicity was quantified in adult male Sprague-Dawley rats. Rats were fed a regular diet or the same diet supplemented with 2.5 g TSO/kg diet for 10 days. TSO treatment did not alter hepatic or renal arylhydrocarbon hydroxylase activity, but significantly increased glutathione S-transferase and uridine diphosphoglucuronyl transferase activities in both organs. In addition, TSO increased hepatic, but not renal, epoxide hydrolase activity. The same treatment did not produce adverse effects on renal or hepatic functions, but markedly potentiated bromobenzene hepatotoxicity. A single dose of bromobenzene (0.2 ml/kg) caused a slight increase in serum glutamic pyruvic transaminase (SGPT) activity and minor hepatic necrosis in animals fed the control diet; the same dose of bromobenzene markedly increased SGPT activity and produced severe hepatic necrosis in the TSO-fed animals.

Effect of piperonyl butoxide on organic anion and cation transport in rabbit kidneys

Piperonyl butoxide has been shown to reduce accumulation of cephaloridine in rabbit renal cortex; however, the mechanism responsible for this effect remains unclear. Cephaloridine is a zwitterion and its accumulation in renal cortex has been suggested to be regulated by both organic anion and cation transport systems. Thus, it was of interest to determine the effect of piperonyl butoxide on renal transport of p-aminohippurate (PAH, an organic anion) and tetraethylammonium (TEA, an organic cation). Although pretreatment with piperonyl butoxide markedly inhibited renal cortical uptake of cephaloridine, the same treatment had less inhibitory effect on either PAH or TEA uptake. Efflux of PAH from preloaded renal cortical slices was enhanced by pretreatment with piperonyl butoxide; however, TEA efflux was unaffected. Thus, piperonyl butoxide appears to have effects on renal membrane functions which result in differential effects on PAH, TEA, and cephaloridine transport.

Nuclear structure: determination of the fate of the nuclear envelope in Drosophila during mitosis using monoclonal antibodies

Libraries of monoclonal antibody against nuclear proteins of Drosophila melanogaster have been established recently to investigate nuclear structure and function. Some of the antibodies have been characterized as being directed against the nuclear envelope. Further studies detailed in this paper describe the fate of the nuclear envelope during mitosis. Indirect immunofluorescence staining of whole developing Drosophila embryos has been used as a system in which nuclear events can be studied both synchronously and in a longitudinal gradient of mitotic structures. The results show a pattern of breakdown and reconstruction of the nuclear envelope in which the antigen is always present in particulate structures. In addition, the processes of antigen rearrangement are shown to be spatially determined throughout mitosis.

Analysis of a distinctive protein in chick retina during development

Soluble proteins from the chick retina were analyzed at various developmental stages by SDS-polyacrylamide gel electrophoresis. A peptide of about 24,000 daltons (24 Kd protein) appeared in the 14-day embryo and gradually increased with embryonic age, maintaining a fairly steady level after hatching. Polypeptides which correspond to actin and tubulin, however, remained almost unchanged during development. The 24 Kd protein was not detected in the cerebrum, tectum, pigment epithelium or vitreous body at any age. To characterize this protein, it was partially purified by gel filtration and ion exchange column chromatography, and its isoelectric point was measured. It was focused in a diffuse spot at about pH 5.5. In the bovine retina, a protein was observed at 24,000 daltons on SDS-polyacrylamide gel, but its isoelectric point was more basic than that of chick retina. It is suggested that the 24 Kd protein is one of the distinctive proteins that increase in concentration during the chick retinal development, and would be closely associated with retinal functions.

Metabolic heterogeneity of the proximal and distal kidney tubules

Proximal and distal tubule suspensions were prepared from kidneys of Sprague-Dawley rats by an isolation procedure on a Percoll gradient. The marker enzymes alkaline phosphatase (brush border) and hexokinase (cytoplasmic) as well as p-aminohippurate transport capacity, gluconeogenic activity and electron microscopy were used to characterize the two kidney tubule suspensions. The results of this study indicate that cytochrome P-450 is localized to the proximal tubular cells and that the O-deethylation of 7-ethoxycoumarin was higher in the proximal than distal fraction. Both proximal and distal tubules showed glucuronidation and deacetylation capacities and a relatively equal distribution of non-protein sulfhydryls. These studies demonstrate metabolic heterogeneity of the nephron, the proximal tubule being the main site of renal xenobiotic metabolism. Understanding of metabolic heterogeneity of proximal and distal kidney tubules should provide important information regarding cell specific mechanisms of nephrotoxicity.

Effects of age and sex on hexachloro-1,3-butadiene toxicity in the Fischer 344 rat

Effects of age and sex on hexachloro-1,3-butadiene (HCBD) nephrotoxicity were determined 24 hours after a single dose (0, 25, 50, 100 or 200 mg/kg) in 28- and 63-day-old Fischer 344 rats. HCBD treatment significantly increased the kidney to body weight ratio but had little effect on the liver to body weight ratio. The 28-day-old rats were more susceptible to HCBD nephrotoxicity judged by elevated blood urea nitrogen, decreased renal cortical accumulation of p-aminohippurate and tetraethylammonium. Adult female rats (63-day-old) appeared to be more susceptible to HCBD nephrotoxicity than males at the low dose (50 mg/kg).

Influence of tooth-to-denture-base discrepancy on space closure following premature loss of deciduous teeth

Influence of tooth-to-denture-base discrepancy on so-called physiologic migration of the first molar was studied on serial dental casts of 116 boys and girls, obtained through a dental health program for school children in an area in which there was no dentist. The alteration of spaces following premature loss of deciduous molars was examined comparing the anterior to posterior discrepancies between tooth and denture base. Modes of space alteration showed positive correlation with the size of the discrepancy, especially in the mandibular dental arches. The space deficiency in the posterior region seemed to have a positive effect on the mesial migration of the first molar. Mesial migration of the first molar seems to be pathologic rather than physiologic and is strongly affected by tooth-to-denture-base discrepancies. Space maintenance does not seem to be useful, because it is not necessary in minimum discrepancy cases and is not effective in severe discrepancy cases.

Effects of piperonyl butoxide on cephalosporin nephrotoxicity in the rabbit. An effect on cephaloridine transport

To evaluate the hypothesis that cytochrome P-450 mixed-function oxidase (MFO) activity may have a causal role in the production of cephalosporin nephrotoxicity, the effects of the MFO inhibitors cobaltous chloride and piperonyl butoxide on the nephrotoxicity of cephaloridine in the rabbit were examined. Although cobaltous chloride had no effect on cephaloridine nephrotoxicity, piperonyl butoxide had a significant protective effect. However, in correlated studies of the effects on the renal cortical uptake and disappearance of cephaloridine, it was found that piperonyl butoxide significantly reduces (by 50%) the cortical concentrations of the cephalosporin, both decreasing its uptake by and increasing its disappearance from tubular cells. Finally, we evaluated the effect of piperonyl butoxide on the nephrotoxicity of cephaloglycin, a more toxic cephalosporin that lacks the thiophene side-ring proposed as the target of MFO activation in earlier studies with cephaloridine. No protection against cephaloglycin was found. It is concluded that these inhibitors of MFO activity do not reduce cephalosporin nephrotoxicity in general, and that the reduction of cephaloridine toxicity by piperonyl butoxide can be explained by an effect on the intracellular concentrations of that particular cephalosporin.

Lipid peroxidation: a possible mechanism of cephaloridine-induced nephrotoxicity

Cephaloridine produces renal cortical injury, but the precise mechanism responsible for this nephrotoxicity remains unclear. Recently cephaloridine has been shown to deplete reduced glutathione (GSH) concentration selectively in renal cortex. Cephaloridine nephrotoxicity can be potentiated by diethyl maleate (a GSH depletor), but no glutathione conjugate can be detected. Thus, it was of interest to investigate further the mechanism of depletion of renal cortical GSH by cephaloridine. In the present study, cephaloridine markedly decreased GSH in rat and rabbit renal cortex while concomitantly increasing oxidized glutathione (GSSG). Furthermore, cephaloridine increased lipid peroxidation specifically in renal cortical cells. Conjugated diene formation (an index of lipid peroxidation) was increased in renal cortex but not in the liver shortly following administration of cephaloridine. Removal of selenium and/or vitamin E from the diet, which should enhance lipid peroxidation, potentiated cephaloridine nephrotoxicity and enhanced cephaloridine-induced morphological damage in the kidney. These findings are consistent with a major role of lipid peroxidation in the etiology of cephaloridine nephrotoxicity.

A library of monoclonal antibodies to nuclear proteins from Drosophila melanogaster embryos. Characterization by a cultured cell assay

To study the structure and function of the cell nucleus, a library of 170 monoclonal antibodies was produced to nuclear antigens from 3-6 h old Drosophila embryos. In preparation for immunization, nuclei were separated, at neutral pH and in the presence of polyamines, into two fractions containing either urea-soluble non-histone nuclear proteins or histones plus small quantities of non-histone proteins complexed to DNA. The antibodies were characterized in a rapid, indirect immunofluorescent assay employing cultured Drosophila cells (Schneider's line 2). Low backgrounds and high specific fluorescence were achieved in this assay by purifying the rhodamine-labelled second antibody on a polystyrene resin and washing the cells with optimal concentrations of detergents. The assay categorized antigens according to their cellular locations: in nuclei, in nuclei plus cytoplasm, or primarily in cytoplasm. A subset of nuclear antigens reacted specifically with the nuclear envelope. In addition, some antibodies were characterized by their reactions with polytene chromosomes. The cultured cell assay provides a new, efficient method for expanding this antibody library. The monoclonal antibodies in the library now provide highly specific tools for investigating structural nuclear proteins and proteins that may be regulatory during embryonic development.

5-hydroxytryptamine stimulates [3H]dopamine release from the fish retina

Serotonin (5-hydroxytryptamine, 5-HT; 0.5 micro M and above) stimulated the release of [3H]dopamine ([3H]DA) from particulate fractions of the carp (Cyprinus carpio) retina. The 5-HT effect was dose- and Ca2+-dependent, and was structurally specific. A similar response was not elicited by the other indoles (5,6-dihydroxytryptamine, 5,7-dihydroxytryptamine, 5-hydroxytryptophan, or 5-hydroxyindoleacetic acid) examined. An increase in [3H]DA release was elicited by addition of 5-HT agonists (5-methoxytryptamine, 5-methoxy-N,N-dimethyltryptamine, and tryptamine), but not antagonized by three 5-HT antagonists (metergolin, methysergide, and spiperone). Either DA alone or noradrenaline (0.5 mM) produced a large increase in [3H]DA release from the particulate fractions, but this action was Ca2+-independent. Further, no significant release of [3H] gamma-aminobutyric acid could be evoked by 5-HT (0.5 mM) under similar experimental conditions. Taken together, the present data suggest that 5-HT stimulates [3H]DA release from the fish retina through a specific receptor-mediated mechanism on dopaminergic terminals, but not through an exchange or nonspecific phenomenon.

Depletion of renal cortical glutathione and nephrotoxicity by cephaloridine, cephalothin and gentamicin in male Sprague-Dawley rats

Cephaloridine and gentamicin are selectively accumulated in renal cortex and produce necrosis or proximal tubular cells. However, the mechanisms responsible for renal cortical accumulation of these two antibiotics are quite different; therefore the early pathogenetic processes may not be the same. In the present study, effects of two cephalosporins (cephaloridine and cephalothin) and an aminoglycoside (gentamicin) on rat renal cortical glutathione were determined. Cephaloridine produced a dose-related depletion of renal cortical glutathione one hour following a single administration of the drug. In contrast, cephalothin in equivalent doses did not reduce renal cortical glutathione. Gentamicin had no effect on renal cortical glutathione, even when an acutely lethal dose (1000 mg/kg) was used. Pretreatment of rats with diethyl maleate (0.4 ml/kg) markedly depleted renal cortical glutathione and this pretreatment also potentiated cephaloridine nephrotoxicity. These results suggest that glutathione may play a protective role against cephaloridine but not gentamicin nephrotoxicity.

Metabolism of acetaminophen by the isolated perfused kidney

Acetaminophen (APAP) produces proximal tubular necrosis in the Fisher 344 rat. This lesion may result from the covalent binding of reactive intermediates of APAP to cellular macromolecules when glutathione (GSH) is sufficiently depleted. Experiments were designed to evaluate the ability of the kidney to convert APAP to reactive electrophilic metabolites capable of depleting renal GSH by quantifying GSH concentrations in isolated perfused kidneys perfused with APAP. Perfusion without APAP reduced (3 X 10(-5) -3 X 10(-5) M) to the perfusion medium further reduced renal GSH content. Treatment of rats with polybrominated biphenyls enhanced the ability of 3 X 10(-8) M APAP to deplete GSH. In contrast, treatment with piperonyl butoxide reduced the depletion of GSH produced by 3 X 10(-5) M APAP. At 3 X 10(-5) M APAP, the glucuronic acid, sulfate and the mercapturic acid conjugates were excreted by the isolate perfused kidneys. After treatment with polybrominated biphenyls, mercapturic acid excretion increased 4-fold, whereas the glucuronic acid and sulfate conjugate excretions were unaffected. These data suggest that the kidney can produce an electrophilic metabolite of APAP which can combine with and deplete renal GSH. An electrophilic metabolite of APAP produced by the kidney may initiate APAP induced renal necrosis.

Renal cortical accumulation of phenobarbital in rats and rabbits: lack of correlation with induction of renal microsomal monooxygenases

Subchronic treatment with phenobarbital induces renal cortical microsomal monooxygenase activities (e.g., ethoxycoumarin O-deethylase, benzphetamine N-demethylase and arylhydrocarbon hydroxylase) and cytochrome P-450 content in rabbits but not in rats. The mechanism responsible for this species-specific difference in renal cortical enzyme induction remains unknown, but may be the result of differences in the renal cortical accumulation of phenobarbital by these two species. Rabbit kidneys may be capable of accumulating more phenobarbital than rat kidneys. In the present study, accumulation of phenobarbital by renal cortical slices and the disposition of phenobarbital in vivo were determined. Both rat and rabbit renal cortical accumulation of phenobarbital was partially energy-dependent and inhibited by SKF-525A. Renal cortical accumulation of phenobarbital in rats was also inhibited by piperonyl butoxide. Accumulation of phenobarbital in rabbit renal cortical slices was not greater than that in rat renal cortical slices. Furthermore, rabbit renal cortex did not accumulate more phenobarbital in vivo than rat renal cortex. These results suggest that the different enzyme inducing effects of phenobarbital in rat and rabbit kidneys is not due to quantitative differences in accumulation of phenobarbital in renal cortex.

Effects of drug-metabolizing enzyme inducers on cephaloridine toxicity in Fischer 344 rats

High doses of cephaloridine produce necrosis of renal proximal tubular cells and this nephrotoxicity has been shown to be reduced by piperonyl butoxide (a mixed-function oxidase inhibitor) in rats and rabbits, and potentiated by phenobarbital (a mixed-function oxidase inducer) in rabbits but not rats. Phenobarbital is known to increase rabbit but not rat renal mixed-function oxidase activities; however, several other compounds such as polybrominated biphenyls (PBB), trans-stilbene oxide (TSO) and beta-naphthoflavone (BNF) have been shown to induce renal enzyme activities in rats. Thus, it was of interest to determine the effects of PBB, TSO and BNF on cephaloridine toxicity in Fischer 344 rats. Nephrotoxicity was estimated by measuring alterations in the kidney-to-body weight ratio, blood urea nitrogen and accumulation of p-aminohippurate (PAH) and tetraethylammonium by renal cortical slices. Hepatotoxicity was quantified as changes in serum glutamic pyruvic transaminase (SGPT) activity. Cephaloridine produced only minor changes in SGPT activity. Animals fed diet supplemented with 100 ppm of PBB for 10 days became less susceptible to cephaloridine nephrotoxicity. Similarly, pretreatment of animals with TSO (300 mg/kg) or BNF (100 mg/kg) for 4 days decreased cephaloridine toxicity. Thus, these results suggest that induction of renal drug-metabolizing enzyme activities by these 3 inducers may enhance some detoxification pathway(s) which convert cephaloridine to a non-toxic metabolite(s). Alternatively, treatments with these inducers may alter cephaloridine pharmacokinetics and decrease renal cortical accumulation of cephaloridine.

Ouabain binding to chick embryo neuroretina during development in ovo and in monolayer cultures

Eight-day-old embryo neuroretinas (NR) were dissociated and cultured as monolayer. [3H]Ouabain binding was investigated during the culture period. [3H]Ouabain binding to NR increases continuously until around the tenth day of culture, but after that it gradually decreased. On the other hand, [3H]ouabain binding to NR during in ovo development continued to increase until the embryo was 20 days old. Na-K-ATPase activity was also compared with [3H]ouabain binding during development in ovo and in monolayer culture. It was found that changes in Na-K-ATPase activity of NR in vitro and in ovo were different from those of [3H]ouabain binding activity. Exposure of NR at the second day of culture to 0.1 mM ouabain for 8 h resulted in the degeneration of some differentiated neurons (rosette-formed cells), but new rosettes were soon re-formed after the withdrawal of ouabain, and [3H]ouabain binding to the ouabain-treated NR was decreased by 30%. Ouabain-treatment of NR in 10-day-old cultures completely destroyed the aggregated neurons, but did not apparently injure the glial cell layer. [3H]Ouabain binding decreased more than 90% in the ouabain-treated NR. These results suggest that [3H]ouabain binding activity of NR and the sensitivity to ouabain toxicity are useful indicators for differentiation and development of neurons in the cultured retinal cells.

Nephrotoxicity and hepatotoxicity of chloroform in mice: effect of deuterium substitution

Chloroform (CHCl3) produces renal and hepatic damage in humans and experimental animals. Deuterium-labeled chloroform (CDCl3) has been reported to be less hepatotoxic than CHCl3 in rats. However, this isotope effect has not been determined in other species or in extrahepatic tissues. In this investigation, the effect of deuterium substitution on the nephrotoxicity and hepatotoxicity of CHCl3 was quantified in male ICR mice. Renal and hepatic damage were determined 24 h after administration on various doses of CHCl3 or CDCl3. Liver damage was estimated by measuring serum glutamic-pyruvic transaminase (SGPT) activity. Nephrotoxicity was evaluated by measuring blood urea nitrogen (BUN) and in vitro renal cortical accumulation of p-aminohippurate (PAH) and tetraethylammonium (TEA). Dose-related hepatotoxicity and nephrotoxicity were observed after administration of CHCl3 and CDCl3. CDCl3 produced less liver damage than CHCl3 in mice, suggesting that mouse liver metabolizes CHCl3 by the same mechanism as rat liver. CDCl3 was also less toxic to kidneys than CHCl3, suggesting that the kidney may metabolize CHCl3 in the same manner as the liver

Induction of drug-metabolizing enzymes and toxicity of trans-stilbene oxide in rat liver and kidney

The effect of trans-stilbene oxide (TSO) on organ function and morphology and on drug-metabolizing enzymes was determined in male Sprague-Dawley rats. TSO (300 or 600 mg/kg) was administered i.p., once daily for 5 consecutive days. At a dose of 3400 mg/kg, TSO did no alter body weight, but increased liver weight. The higher dose (600 mg/kg) markedly decreased body weight. TSO treatment (300 mg/kg) induced several drug-metabolizing enzymes. Epoxide hydrolase activity was enhanced in the liver, kidney and lung. In contrast, arylhydrocarbon hydroxylase activity was not significantly altered. Glutathione S-transferase activity, with 1-chloro-2,4-dinitrobenzene as substrate, and uridine diphosphoglucuronyl transferase activity, with p-nitrophenol as substrate, were also increased in the liver and kidney after TSO treatment. It appears that TSO induces hepatic and renal enzyme activities in a similar manner. Treatment with the higher dose of TSO depressed accumulation of p-amino-hippurate by renal cortical slices and increased blood urea nitrogen concentration. Histological examination of kidney sections after treatment with TSO revealed no abnormality. The lower dose led to negligible alteration in liver and the higher dose resulted in mild to moderate hepatic cellular.

Ascorbic acid, an endogenous factor required for acetylcholine release from the synaptic vesicles

The ACh-releasing factor, which is required for ACh release in presence of 2 mM ATP, 2 mM Mg and 10(-5) M Ca from isolated synaptic vesicles, was purified from the synaptosomal cytoplasm of rat brain by Sephadex G-15, DEAE-Sephadex, Sephadex G-10 and AG50W-2X column chromatographies and identified as ascorbic acid. A low concentration of L-ascorbic acid (5 x 10(-6) M) produced a release of ACh from the vesicles in the presence of ATP, MgCl2 and CaCl2, as did synaptosomal cytoplasm. This release of ACh induced by L-ascorbic acid was found to be dissociable from formation of lipid peroxide. These findings are discussed in relation to the physiological role of L-ascorbic acid in the brain.