Incidence of p53 and Ha-ras gene mutations in chemically induced rat mammary carcinomas

To determine whether p53 alterations, which are frequent in human breast cancers, are also common in rat mammary tumors, we examined 40 tumors from 24 rats treated with 7,12-dimethylbenz[a]anthracene (DMBA) and 34 tumors from 14 rats treated with N-nitroso-N-methylurea (NMU) (an N-nitroso compound). DMBA and NMU are known genotoxic mutagens. The entire coding regions of the p53 and Ha-ras genes were examined for mutations by polymerase chain reaction single-strand conformational polymorphism analysis and by direct sequencing. One of the 40 DMBA-induced mammary tumors had a p53 mutation, a single-base substitution (AGC-->GGC) at codon 307, resulting in an amino-acid change from Ser to Gly. No mutations were found in NMU-induced tumors. The incidence of Ha-ras gene mutation was 79% (27 of 34) at codon 12 in the NMU group and 23% (nine of 40) at codon 61 in the DMBA group. Thus, p53 mutation, in contrast to Ha-ras mutation, did not seem to be a prerequisite for carcinogenesis in chemically induced rat mammary tumors.

Distribution of Ca2+ channels on cochlear outer hair cells revealed by fluorescent dihydropyridines

Physiological evidence has shown that cochlear outer hair cells (OHC) possess L-type voltage-dependent Ca2+ channels through which Ca2+ enters the OHC during depolarization. Their subcellular distribution has, however, remained unclear. In this study, the distribution of L-type Ca2+ channels on the basolateral plasma membrane of OHC has been demonstrated by the use of a laser scanning confocal microscope (LSCM) and a fluorescent probe DMBODIPY-DHP. The fluorescent staining pattern on the basolateral wall is nonuniform, suggesting a heterogeneous distribution of the channels in the plasma membrane. Direct imaging of intracellular Ca2+ visualized in real time by means of the LSCM and the fluorescent Ca2+ probe fluo 3 revealed temporal and spatial integration of Ca2+ movements and Ca2+ channel distribution. Exposure to high-K+ solution induced heterogeneity in the subcellular increase in the intracellular Ca2+ concentration. These results suggest that the heterogeneous distribution of L-type Ca2+ channels on the basolateral membrane might induce heterogeneous intracellular Ca2+ distribution during electrical activity in the OHC.

Enzymes for anandamide biosynthesis and metabolism

Anandamide is an endogenous ligand for cannabinoid receptors. We tried to isolate and purify "anandamide amidohydrolase' which hydrolyzes anandamide to arachidonic acid and ethanolamine. The enzyme activity was found in the microsomal fraction of porcine brain homogenate. The enzyme was solubilized in 1% Triton X-100, and partially purified by hydrophobic chromatography to a specific activity of about 0.3 mumol/min per mg protein (37 degrees C). Apparent K(m) for anandamide was about 60 microM. The enzyme reacted also with ethanolamides of linoleic, oleic, and palmitic acids at lower rates. This enzyme preparation also converted arachidonic acid to anandamide in the presence of 250 mM concentration of ethanolamine. Several lines of evidence including experiments using various inhibitors suggested that the anandamide synthase and amidohydrolase activities were derived from a single enzyme protein.

Immunohistochemical detection of truncated APC protein in sporadic human colorectal adenomas and adenocarcinomas

Mutations of the APC gene frequently occur in sporadic forms of colorectal adenomas and adenocarcinomas. Phenotypically, the vast majority of these mutations result in the truncation of the APC protein. To demonstrate the defective APC gene product in human colorectal tumors, rabbit region-specific antisera raised against the APC protein of amino acid sequences between 371 and 390 (SPI) and between 1821 and 1840 (SP3) were used to exhibit the truncated APC protein. In all, 86 lesions from 67 cases of sporadic adenoma and adenocarcinoma were examined; abnormal staining patterns were distinguished in 43 lesions (50%); the incidence of abnormalities was not significantly different between adenomas and carcinomas. The majority, 75% exhibited epitopic change with the SPI-positive and SP3-negative phenotype (type P1), and 25% exhibited neither of these phenotypes (type P2). The staining pattern in all lesions was uniform, and studies of carcinomas arising in adenomas showed the same pattern of staining. These findings supported the view that the APC lesion is a very early event in colorectal carcinogenesis. Furthermore, this simple immunohistochemical approach demonstrated that different adenomas from the same patient showed different staining patterns.

Kidney iron status in passive Heymann nephritis and the effect of an iron-deficient diet

In the study presented here, the iron status in the kidney in passive Heymann nephritis, a complement-dependent model of membranous nephropathy, was examined. To examine whether the effect of immune injury on iron status has a pathogenic role, the effect of an iron-deficient diet was also determined. Injection of the anti-Fx1A antibody (10 mg/100 g body wt) in Sprague-Dawley rats resulted in no change in the serum iron level, a marked increase in the urinary excretion rate of iron, a marked increase in non-heme iron content of kidney cortex, and a marked increase in the non-heme iron level in tubules. These increases in iron were prevented by feeding the rats an iron-deficient diet. In the rats fed a normal iron diet and injected with anti-Fx1A-lgG, there was no significant change in the non-heme iron level in glomeruli. However, an iron-deficient diet resulted in a significant decrease in the non-heme iron level in glomeruli, compared with its respective control. In addition, an iron-deficient diet significantly reduced urinary protein excretion rate (Day 5: iron-replete, 68 +/- 12 mg/24 h, N = 12; iron-deficient, 36 +/- 11, N = 10, P < 0.05) in the complement-dependent immune phase of the glomerular injury. Taken together, these data indicate a marked alteration in the iron status in the kidney and suggest an important role of iron in glomerular injury of passive Heymann nephritis.

Diurnal heart rate variability in healthy subjects: effects of aging and sex difference

To study the effects of aging and gender, circadian profiles of heart rate variability were evaluated for 105 healthy volunteers by frequency domain analysis of a Holter electrocardiogram record. The low-frequency (LF) component representing cardiac beta-adrenergic function showed high values for the 0800-1200 period in male subjects and the 1200-2400 period in female subjects. The high-frequency (HF) component representing parasympathetic function showed a peak for the 0000-0600 period in both male and female subjects independent of age. Male subjects showed significantly higher %LF [LF/(LF + HF) x 100] than female subjects. LF showed consistently highly significant correlation with age. These basic findings can help elucidate the diurnal profile of cardiac nerve function and how it is affected by aging and sex difference.

Inhibition of TGF-beta 1 expression by antisense oligonucleotides suppressed extracellular matrix accumulation in experimental glomerulonephritis

Overproduction of transforming growth factor-beta 1 (TGF-beta 1) has been implicated in the pathogenesis of fibrotic diseases. TGF-beta 1 plays a crucial role in the accumulation of extracellular matrix (ECM) in human and experimental glomerular diseases. However, it remains unclear whether inhibition of TGF-beta 1 overproduction would suppress TGF-beta 1-induced ECM accumulation. To inhibit the overproduction of TGF-beta 1 in experimental glomerulonephritis induced by anti-Thy 1.1 antibody, we introduced antisense oligodeoxynucleotides (ODN) for TGF-beta 1 into the nephritic kidney by the HVJ-liposome-mediated gene transfer method. Sense, scrambled or reverse ODN were also introduced as controls. Transfected ODN accumulated mainly in the nuclei of mesangial cells in the glomeruli of transfected kidneys. In the antisense ODN-transfected rats, a marked decrease in expression of TGF-beta 1 mRNA was confirmed by Northern analysis. Consequently, the expression of TGF-beta 1 protein in the glomerulus was markedly reduced in the antisense ODN-transfected kidney with a comparable effect in preventing glomerular ECM expansion in experimental glomerulonephritis. In contrast, sense, scrambled and reverse ODNs failed to suppress TGF-beta 1 expression and ECM accumulation. Thus, these results suggested that inhibition of TGF-beta 1 overproduction could suppress progression to glomerulosclerosis.

Role of protein phosphatase in malignant osteogenic and soft tissue tumors

The expression of the three catalytic subunits of protein phosphatase (PP) type 1 and 2A, PP1 alpha, PP1 gamma 1, and PP2AC, was examined in osteogenic tumors and soft tissue tumors by immunohistochemical analysis. The percentage of cells stained positively with antiserum against PP1 catalytic subunit isoform PP1 gamma 1, was significantly higher in malignant osteogenic tumors (chondrosarcoma, osteosarcoma, and Ewing's sarcoma) and in malignant soft tissue tumors (liposarcoma and malignant fibrous histiocytoma [M.F.H.]) than in benign tumors (osteochondroma, osteoblastoma, ossifying fibroma, enchondroma and lipoma). Furthermore, the malignant tumor lesions showed a markedly high number of cells in the S-phase fraction of the cell cycle, as compared to benign tumors. These results suggest that PP1 gamma 1 is involved in the accelerated growth of malignant tumor cells.

Role of reactive oxygen metabolites in DNA damage and cell death in chemical hypoxic injury to LLC-PK1 cells

Hypoxia is considered to result in a necrotic form of cell injury. We have recently demonstrated a role of endonuclease activation, generally considered a feature of apoptosis, to be almost entirely responsible for DNA damage in hypoxic injury to renal tubular epithelial cells. The role of reactive oxygen metabolites in endonuclease-induced DNA damage and cell death in chemical hypoxic injury has not been previously examined. LLC-PK1 cells exposed to chemical hypoxia with antimycin A resulted in enhanced generation of intracellular reactive oxygen species as measured by oxidation of a sensitive fluorescent probe, 2',7'-dichlorofluorescin diacetate. Superoxide dismutase, a scavenger of superoxide radical, significantly reduced the fluorescence induced by antimycin A and provided significant protection against chemical hypoxia-induced DNA strand breaks (as measured by the alkaline unwinding assay). Pyruvate, a scavenger of hydrogen peroxide, provided significant protection against chemical hypoxia-induced DNA strand breaks and DNA fragmentation (as measured by agarose gel electrophoresis). The interaction between superoxide anion and hydrogen peroxide in the presence of a metal catalyst leads to generation of other oxidant species such as hydroxyl radical. Hydroxyl radical scavengers, dimethylthiourea, salicylate, and sodium benzoate, and two metal chelators, deferoxamine and 1,10-phenanthroline, also provided marked protection against DNA strand breaks and DNA fragmentation. These scavengers of reactive oxygen metabolites and metal chelators provided significant protection against cell death as measured by trypan blue exclusion and lactate dehydrogenase release. Taken together, these data indicate that reactive oxygen species play an important role in the endonuclease activation and consequent DNA damage, as well as cell death in chemical hypoxic injury to renal tubular epithelial cells.

Angiotensin I-converting enzyme insertion/deletion polymorphism: potential significance in nephrology

Angiotensin I-converting enzyme (ACE) plays a pivotal role in cardiovascular homeostasis and by activating angiotensin I into angiotensin II and inactivating bradykinin. These two peptides play antagonistic roles on the cardiovascular system by regulating vascular tone and vascular smooth muscle cell proliferation. Identification of the ACE gene as a genetic marker for various forms of cardiovascular disease is a recent result of the progress made in molecular biology and genetics. The insertion/deletion (ID) polymorphism of the ACE gene defined by the presence or absence of the 287 base pair Alu sequence situated in intron 16 has been investigated as a possible genetic marker for a variety of cardiovascular disease including myocardial infarction, essential hypertension, cardiomyopathy, and diabetic vascular complications. This paper reviews prior reports and briefly describes our recent study on the association of the ACE I/D polymorphism and antiproteinuric effect of ACE inhibitors in patients with proteinuria.

Subcellular distribution of protein kinase C in the living outer hair cell of the guinea pig cochlea

Immunohistochemical staining using isoform-specific antibodies and intracellular localization using fluorescent probes for protein kinase C (PKC) were evaluated in the cochlear outer hair cell (OHC). Among three isoforms of classic PKC, PKC alpha was selectively stained in the fixed OHC as well as inner hair cells under a surface preparation method. Two types of fluorescent probes to detect subcellular localization of PKC were observed with a confocal laser scanning microscopy in the present study, fim-1 diacetate which binds to the ATP-competitive catalytic domain of PKC and Bodipy FL C12-phorbol acetate which binds to specific site localized to the first cysteine-rich loop of the C1 region in the regulatory domain. High fluorescence intensity of both dyes was observed in subcuticular and subsynaptic regions, infracuticular network, and along the lateral wall. The displacement experiments to evaluate binding specificity were performed by incubating Bodipy FL C12-phorbol acetate in the presence of 10 microM phorbol 12-myritate 13-acetate (PMA) and the fluorescence was totally disappeared. For the acute treatment of phorbol ester, cells were preincubated with 1 microM PMA 30 min before loading with fim-1 diacetate. The brightest area in the plasma membrane became much larger as compared with untreated cells, which suggests a dramatic translocation of PKC to the plasma membrane. The biological functions involving PKC in the OHC are discussed.

A low-affinity vasopressin V2-receptor gene in a kindred with X-linked nephrogenic diabetes insipidus

In this study, a mutation in vasopressin Type 2 receptor (V2R) in a patient with hereditary nephrogenic diabetes insipidus (NDI) has been identified and characterized. The sequencing of the V2R gene from the patient revealed that there was a missense mutation (TAT to TGT) resulting in the substitution of 205Tyr for Cys in the putative third extracellular domain. The expression analysis in COS cells showed that the binding affinity of the mutant receptor (KD = 19.8 nM) for arginine vasopressin was much lower than that of the wild-type receptor (KD = 1.8 nM) so that intracellular cAMP production stimulated by arginine vasopressin was impaired in cells with the mutant V2R. From these results, it was concluded that the single amino-acid substitution of V2R is responsible for this familial disease.

Role of 'catalytic' iron in an animal model of minimal change nephrotic syndrome

Treatment of minimal change disease, like most glomerulonephritides, is empirical because underlying mechanisms that cause glomerular injury are not known. We examined a pathogenic role of 'catalytic' iron in a model of minimal change nephrotic syndrome induced by injection of puromycin aminonucleoside (7.5 mg/100 g body wt) to rats. Although there was no significant change in non-heme iron content in glomeruli, the bleomycin-detectable iron (capable of catalyzing free radical reactions) was markedly increased in glomeruli from nephrotic rats when compared to control. In contrast, despite a marked and significant increase in the non-heme iron content in tubules, there was no significant change in the bleomycin-detectable iron in tubules from nephrotic rats. In a separate in vivo study, the iron chelator, deferoxamine, prevented the increase in the bleomycin-detectable iron in glomeruli and provided complete protection against proteinuria. Taken together, our data suggest an important pathogenetic role for glomerular catalytic iron in the puromycin aminonucleoside-induced minimal change nephrotic syndrome.

Altered carbohydrate composition in colorectal adenomas and carcinomas: histochemical characterization of N-acetylgalactosamine, L-fucose, and o-acetylated sialic acid

Changes of surface sugar residues in the large intestinal mucosa may be associated with malignant transformation and may be of importance in differentiating borderline lesions. To compare these changes in normal mucosa, adenomas, and carcinomas of the large intestine, we investigated modifications of carbohydrate composition, such as those of N-acetyl-galactosamine (GalNac), L-fucose, and o-acetylated sialic acid, by histochemical staining with Dolichos biflorus agglutinin (DBA) and Ulex europaeus agglutinin-1 (UEA-1) lectins, and with Culling's periodic acid-thionin Schiff/potassium hydroxide/periodic acid-Schiff (PAT/KOH/PAS), respectively. For stable staining, the sections stained with DBA and UEA-1 were pretreated with potassium hydroxide and neuraminidase. We conclude that the pattern of the two lectin stainings in carcinomas is quite different from that in normal mucosa and adenomas, and that it shows the carcinomatous features in some cases of adenoma with severe atypia (borderline lesions). In contrast, PAT/KOH/PAS staining demonstrates differences between normal mucosa and adenomas rather than differences between adenomas and carcinomas.

Endonuclease induced DNA damage and cell death in chemical hypoxic injury to LLC-PK1 cells

Hypoxia is considered to result in a necrotic form of cell injury. We examined the role of endonuclease activation, considered a feature of apoptosis, in DNA damage and cell death in hypoxic injury in LLC-PK1 cells. Hypoxia in LLC-PK1 cells was induced using a combination of glucose deprivation and a mitochondrial inhibitor, antimycin A (10 microM). Chemical hypoxia caused DNA damage as measured by the alkaline unwinding assay and internucleosomal DNA fragmentation that preceded cell death. Incubating protein extract of cells subjected to chemical hypoxia with calf thymus DNA resulted in oligonucleosome length fragments, which were prevented by an endonuclease inhibitor, aurintricarboxylic acid. Chemical hypoxia resulted in an increased DNA degrading activity with a molecular mass of approximately 15 kDa. Endonuclease inhibitors, aurintricarboxylic acid and Evans blue, prevented antimycin A-induced DNA strand breaks, fragmentation and cell death. We conclude that endonuclease activation plays an important role in chemical hypoxic injury to LLC-PK1 cells.

Bilateral sensorineural hearing loss associated with the point mutation in mitochondrial genome

Mitochondrial DNA (mtDNA) mutation associated with sensorineural hearing loss (SNHL) has previously been described in MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) and in aminoglycoside-induced deafness. The authors of this study report three cases of SNHL associated with mtDNA mutation (3243A-->G). They examined the clinical features of this type of SNHL by audiologic studies and examined the mtDNA mutation by the polymerase chain reaction technique. In the three cases described, the SNHL had an adult onset and was bilateral and symmetrical. All patients had adult-onset diabetes mellitus. Audiologic studies revealed that the SNHL in all patients derived from the cochlea rather than from retrocochlear sites. It is presumed that mtDNA mutation results in mitochondrial dysfunction in cochlear tissues (i.e., hair cells and stria vascularis) and in neurons of the auditory pathway. Genetic analysis of mtDNA offers new insight into the diagnosis and treatment of SNHL.

Arachidonate 12-lipoxygenase in porcine anterior pituitary cells: its localization and possible function in gonadotrophs

Arachidonate 12-lipoxygenase, which oxygenates positions 12 and 13 of arachidonic and linoleic acids, is present in porcine anterior pituitary cells. Colocalization of the 12-lipoxygenase with various pituitary hormones was examined by immunohistochemical double-staining using antibodies against 12-lipoxygenase and various anterior pituitary hormones. Under light microscopy, approximately 7% of the cells producing luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were positive for 12-lipoxygenase, whereas the enzyme was detected in less than 2% of the cells producing thyrotrophin, prolactin, growth hormone (GH), and adrenocorticotrophin. In an attempt to examine the participation of 12-lipoxygenase metabolites in pituitary hormone release, we incubated the primary culture of porcine anterior pituitary cells with 12-hydroperoxy-arachidonic acid or 13-hydroperoxy-linoleic acid. Significant stimulation of LH and FSH release by these hydroperoxides was observed at 10 microM in a time-dependent manner. At doses around 10 microM these compounds produced responses of similar magnitude to 1 nM gonadotrophin-releasing hormone (GnRH), but higher concentrations (30 microM) of the compounds were required for GH release. In contrast, 12-hydroxy-arachidonic and 13-hydroxy-linoleic acids were almost ineffective. Furthermore, the gonadotrophin release by 1 nM GnRH was inhibited by nordihydroguaiaretic acid (a lipoxygenase inhibitor) with an IC50 of about 5 microM. Thus, the hydroperoxy (but not hydroxy) products of 12-lipoxygenase may be involved in the release of pituitary hormones especially LH and FSH.

Transcriptional roles of nuclear factor kappa B and nuclear factor-interleukin-6 in the tumor necrosis factor alpha-dependent induction of cyclooxygenase-2 in MC3T3-E1 cells

When a mouse osteoblastic cell line MC3T3-E1 was cultured in the presence of tumor necrosis factor alpha (TNF alpha), the release of prostaglandin E2 and the cyclooxygenase activity increased in a dose- and time-dependent manner. The increase of the enzyme activity was attributed mostly to the induction of cyclooxygenase-2 rather than cyclooxygenase-1 as judged by the inhibitory effect of NS398, Western blotting, and Northern blotting. In this system we attempted to elucidate the transcriptional regulation of the cyclooxygenase-2 gene. As examined by the luciferase assay, two positive regulatory regions (-186 to -131 and -512 to -385 base pairs) were found in the 5'-flanking promoter region of the mouse cyclooxygenase-2 gene in the TNF alpha-stimulated cells. The former included putative NF-IL6 (C/EBP beta) and AP2 elements, and the latter contained the NF kappa B motif. A DNA probe including the NF-IL6 and AP2 sites gave positive bands upon electrophoretic mobility shift assay using the nuclear extracts of MC3T3-E1 cells. The bands were supershifted by the addition of anti-NF-IL6 antibody but not by anti-AP2 antibody. A probe including the NF kappa B site also gave positive bands, which were supershifted by anti-NF kappa B p50 and p65 antibodies. Furthermore, when the motif of NF-IL6 or NF kappa B or both was subjected to point mutation, the luciferase activity was markedly reduced. These data suggested a potential role of both NF-IL6 and NF kappa B in the induction of cyclooxygenase-2 by TNF alpha.

Association of angiotensin I-converting enzyme gene polymorphism with susceptibility to antiproteinuric effect of angiotensin I-converting enzyme inhibitors in patients with proteinuria

The antiproteinuric effect of angiotensin I-converting enzyme (ACE) inhibitors in patients with renal diseases of various origins has been well recognized. However, individual responses regarding the degree of decrease in urinary protein excretion appear to vary considerably. The mechanism underlying this variable response to ACE inhibitors has not been clarified yet. A possible role of ACE gene insertion/deletion (I/D) polymorphism in the responsiveness to antiproteinuric effect of ACE inhibitors is examined. Thirty-six patients with proteinuria (23 men and 13 woman; mean age, 47 +/- 13 yr) were studied. These patients were classified into two groups on the basis of the percent decrease in their urinary protein excretion: the effective group, those with a decrease in proteinuria (18 patients, -64 +/- 19%) and the noneffective group (18 patients, +13 +/- 40%). A 287-base pair (bp) I/D polymorphism in the ACE gene was examined by polymerase chain reaction. The allelic frequencies of the ACE gene were I/D = 0.53/0.47 in the effective group and I/D = 0.81/0.19 in the noneffective group. The difference in the allelic frequencies between the two groups was significant (chi 2 = 6.25, P = 0.0114 < 0.05). Furthermore, the difference in the responsiveness of proteinuria to ACE inhibition between genotype II versus genotype ID + DD was statistically significant (chi 2 = 4.05, P = 0.0442 < 0.05). There was no significant difference between the two groups with regard to initial urinary protein level, blood pressure, renal function, and daily sodium intake. The genetic susceptibility to the antihypertensive effect of ACE inhibitors was also studied, but no significant relation was observed. This study suggests the association of ACE gene I/D polymorphism with the antiproteinuric efficacy of ACE inhibitors in patients with proteinuria.

[Clinical study of bronchial asthma in adult, intractable asthmatics after introduction of guideline therapy]

Introduction of Guideline for asthma treatment proposed by the committee of Japanese allergology have a tremendous impact on patients with bronchial asthma. Intractable asthmatics who have had to take some oral steroid to overcome disease severity, may have also some merit by this treatment, so that some of them might be no longer considered as intractable asthmatics. To clarify this, multicenter study was conducted. In this study, a case who have had more than 5 mg of prednisolone and/or 800 mu g of beclomethasone dipropionate throughout the year, was diagnosed as intractable asthmatics. In 845 case, 14.7%, 123 cases were diagnosed as intractable. These cases were significantly to be non-atopic and adult onset. Also, they have a significant tendency to be deteriorated by infection and careless drug administrations. Using the multiquantification method to examine the most powerful factor on intractable asthmatics, type of asthmatics was the most important and the past history of severe attack was the second. When intractable asthmatics diagnosed mainly by their BDP usage (BDP-intractable) were compared with intractable diagnosed by oral PSL (PSL-intractables), BDP-intractables were significantly atopic compared to PSL-intractables.