Effects of a nonpeptide vasopressin antagonist (OPC-21268) on cytosolic Ca2+ concentration in vascular and cardiac myocytes

A selective V1 antagonist, 1-(1-[4(3-acetylaminopropoxy)benzoyl]-4-piperidyl)-3,4-dihydro-2(1 H)- quinolinone (OPC-21268), which is nonpeptide and orally effective, has been recently synthesized. We studied the effects of vasopressin and OPC-21268 on cell contraction with a video motion detector and cytosolic Ca2+ concentration ([Ca2+]i) by using indo-1 in cultured rat vascular smooth muscle cells and cultured chick embryo ventricular myocytes. Exposure of cultured vascular smooth muscle cells to vasopressin (1-100 nM) dose-dependently produced an initial transient increase (from control level [Ca2+]i of 133.6 +/- 10.9 nM to peak [Ca2+]i of 842.7 +/- 172.8 nM at 100 nM vasopressin, p less than 0.01) and then a small sustained increase in [Ca2+]i. After pretreatment of vascular smooth muscle cells with 1 microM OPC-21268, the effects of 100 nM vasopressin on [Ca2+]i were abolished. Exposure of ventricular myocytes to 100 nM vasopressin slightly but significantly decreased peak systolic cell position (-8.7 +/- 3.7%, p less than 0.05) and also produced reductions in peak systolic [Ca2+]i (from 962.2 +/- 76.4 to 751.2 +/- 70.5 nM, p less than 0.01) within 30 seconds. Pretreatment of ventricular myocytes with OPC-21268 (1 microM) completely suppressed vasopressin-induced changes in peak systolic cell position and [Ca2+]i. These results suggest that vasopressin may increase vascular tone and may also cause a direct negative inotropic effect via V1 receptors and that this orally active V1 antagonist (OPC-21268) may have potential clinical usefulness.

A novel ETA antagonist (BQ-123) inhibits endothelin-1-induced phosphoinositide breakdown and DNA synthesis in rat vascular smooth muscle cells

The effects of a novel cyclic pentapeptide (BQ-123), an endothelin (ET) antagonist selective for the ETA receptor subtype, on phosphoinositide breakdown and DNA synthesis stimulated by ET-1 were studied in cultured rat vascular smooth muscle cells (VSMC). BQ-123 competitively inhibited the binding of [125I]ET-1 to VSMC with the apparent Ki of 4 x 10(-9) M. BQ-123 dose-dependently inhibited formation of inositol-1,4,5-trisphosphate and [3H]thymidine uptake stimulated by ET-1. These data suggest that the ET-1-induced DNA synthesis in VSMC is mainly mediated by ETA receptor subtype.

Endothelin receptors in human parathyroid gland

We studied whether specific receptors for endothelins (ETs) exist in human parathyroid tissues and whether ETs may have any effect on secretion of PTH from parathyroid cells. Binding studies using [125I]ET-1 to the parathyroid membranes obtained from patients with hyperparathyroidism (2 adenomas, 2 hyperplasias) revealed that ET-1 competitively inhibited the binding of [125I]ET-1 to the membranes (the apparent Kd: 62 +/- 18 pM), whereas ET-3 showed biphasic and less steep inhibition curve than ET-1 in all tissue membranes examined. Northern blot analysis of poly(A)+ RNA from the parathyroid adenoma clearly demonstrated gene expression of both ETA and ETB receptors as well as preproET-1. ET-1 inhibited basal PTH secretion from dispersed adenoma cells more potently than ET-3. The present study clearly demonstrates the presence of both ETA and ETB receptor subtypes in human parathyroid tissues through which ETs may modulate PTH secretion in an autocrine and/or paracrine manner.

Detection of novel germ-line p53 mutations in diverse-cancer-prone families identified by selecting patients with childhood adrenocortical carcinoma

BACKGROUND

Germ-line p53 mutations appear to be inherited among the members of families diagnosed with Li-Fraumeni syndrome (LFS). The mutations detected in those families to date have been clustered in exon 7 of the p53 gene and, typically, have been single-base substitutions resulting in amino acid changes.

PURPOSE

Our aim was to define the spectrum of p53 mutations associated with LFS.

METHODS

From seven cancer-prone families identified by selecting members with childhood adrenocortical carcinoma as probands, we chose two families, each of which had two members from whom specimens could be obtained for genetic analysis. To detect germ-line p53 gene mutations in these individuals, we performed polymerase chain reaction (PCR)-single-strand conformation polymorphism analysis with Taq polymerase and oligonucleotide primers specific for p53 gene sequences. Genomic DNA extracted from fresh tissue samples and paraffin-embedded tumor samples was amplified, denatured, and electrophoresed on neutral polyacrylamide gels. PCR amplification was also carried out using total RNA from adrenocortical carcinoma samples of the proband in family 1. PCR products were purified, subcloned, and sequenced.

RESULTS

We detected novel germ-line p53 mutations in affected members of both cancer-prone families. In the proband of family 1, a single-base deletion was detected at the first nucleotide of codon 307 in exon 8 of the p53 gene, resulting in a premature stop codon in exon 10. In family 2, we detected an A to C transversion at the second nucleotide of codon 286 in exon 8, both in DNA isolated from the adrenocortical tumor of the proband and in DNA isolated from the astrocytoma of the proband's father. This single-base substitution resulted in an amino acid substitution of alanine for glutamic acid. Both of these mutations are located outside the highly conserved region of the p53 gene where mutations in patients with LFS have been reported previously.

CONCLUSION

Our results indicate that a wide range of germ-line p53 mutations is inherited in members of diverse-cancer-prone families.

Investigation of the mode of inheritance of insulin-dependent diabetes mellitus in Japanese subjects

Previous studies have shown that insulin-dependent diabetes mellitus is positively associated with HLA-DR4 and HLA-DR9 in Japanese populations. It was proposed that susceptibility to the disease is determined by a single HLA allele associated with both DR4 and DR9. DR genotypes in a Japanese population with insulin-dependent diabetes mellitus were determined by DRB/DQB RFLP analysis. A single disease-susceptibility-allele model was tested by the antigen-genotype-frequency-among-patients method. Recessive and additive inheritance of a single susceptibility allele were rejected. The DR9-associated disease-susceptibility allele in Japanese subjects is distinct from both the DR3- and DR4-associated susceptibility alleles in white Caucasians. The data suggest further complexity in the inheritance of HLA-associated susceptibility to insulin-dependent diabetes mellitus.

[Multiple resistance to drugs by MRSA]

Most methicillin-resistant Staphylococcus aureus (MRSA) isolates are multiply resistant to various antimicrobial agents. Therefore, MRSA strains have become a serious problem in the clinical setting. However, it should be noted that the frequency of isolation of strains resistant to aminoglycoside and minocycline was not significantly different between low- and high-MRSA isolates and the isolation frequency of high-MRSA strains, less susceptible to not only beta-lactam antibiotics but also to macrolide antibiotics and quinolones, was significantly higher than the corresponding values for low-MRSA strains. These results suggest that high-MRSA strains were selected by antimicrobial agents for the treatment with the patients.

Increased production of endothelin-1 in patients with inflammatory arthritides

OBJECTIVE

Endothelin-1 (ET-1) is a potent vasoconstrictive peptide, but its precise mechanism of action in vivo has remained unknown.

METHODS

We measured ET-1 activity by radioimmunoassay, in both plasma and synovial fluid from patients with inflammatory arthritides.

RESULTS

ET-1-like immunoreactivity was found in synovial fluid, at levels severalfold higher than those in plasma. Reverse-phase high-performance liquid chromatography showed an elution profile corresponding to actual ET-1. A single class of high-affinity binding sites for ET-1 in cultured synovial cells was also detected. Furthermore, ET-1 induced mild DNA synthesis in synovial cells.

CONCLUSION

Taken together, these results indicate that ET-1 might contribute to the synovial proliferation seen in inflammatory arthritides, in an autocrine/paracrine manner.

Intervarietal and interspecific chimera formation by in vitro graft-culture method in Brassica

An efficient chimera formation method by tissue culture combined with grafting was studied in Brassica. Cabbage cultivars "Ruby-ball" and "YR-ranpou" (Brassica oleracea) were used for intervarietal chimera formation. Seven-day-old seedlings leaving one of two cotyledons were approach-grafted and cultured in vitro (AGSC method). Chimeric shoots were obtained by the subculture of directly growing chimeric leaves (DGCL) from grafted part and cross-cut section of the united part after the graft culture. These were rooted and grown to complete chimera. An approach-grafted culture method was also available for interspecific chimera formation between "Komatsuna" (B. campestris) and "Ruby-ball" (B. oleracea), resulting in 20% formation per culture. Interspecific chimeras were identified as complex and peripheral-sectorial type by microscopic observation and the electrophoretic analysis of acid phosphatase isozyme pattern. The AGSC method was more effective than the usual Winkler's graft method and a simple mixed culture of heterogeneous cells or tissues.

Structure of the bovine endothelin-B receptor gene and its tissue-specific expression revealed by northern analysis

We have isolated and characterized the gene encoding the bovine endothelin (ET) receptor ETB with seven putative membrane-spanning domains. The gene exists as a single copy of the bovine genome and extends over 36 kilobases. The coding region is divided into seven exons separated by six introns; the first exon encodes the first and second transmembrane domains and each of the following transmembrane domains is encoded by a separate exon. The 5' region of the transcript was examined by the ribonuclease protection analysis; multiple start sites were deduced with no apparent "TATA" box in the expected upstream region. Northern blot analysis demonstrated a widespread but tissue-specific distribution of the ETB receptor in bovine tissues.

An insulin-like growth factor II-producing histiocytoma associated with hypoglycemia: analysis of the peptide, its gene expression, and glucose transporter isoforms

An insulin-like growth factor II (IGF-II)-producing histiocytoma was detected in a patient presenting with the classical findings of tumor-related hypoglycemia (low serum insulin and IGF-I concentrations, glucose intolerance, and only modestly increased serum IGF-II levels). Acid-gel filtration of serum extracts showed a single peak of IGF-II immunoreactivity that emerged at the same site as the 125I-labeled human IGF-II standard. High-performance liquid chromatography (HPLC) analysis of the tumor IGF-II demonstrated that it had an identical retention time to that of recombinant human IGF-II. The tumor IGF-II content was extremely high, messenger RNA (mRNA) for IGF-II showed a 100-fold increase in expression compared with normal human liver tissue. Of special interest, a newly identified exon (hE1) was shown to be predominantly expressed in the tumor by Northern blot analysis using leader exon-specific rat IGF-II complementary DNA (cDNA) probes. Although the significance of this finding remains uncertain, this is the first evidence of a new transcription unit in the human IGF-II gene. In addition, immunoblotting showed that the levels of the glucose transporters, GLUT1 and GLUT4, in the tumor were low and undetectable, respectively. This finding makes it unlikely that increased glucose consumption by the tumor accounted for the hypoglycemia in this patient. This case report provides an interesting insight into the pathophysiology of tumor-induced hypoglycemia and new evidence of the abnormal regulation of IGF-II gene expression in human tumors.

[A patient with liver cirrhosis manifesting various symptoms including cerebellar ataxia due to germanium intoxication]

A patient with hepatitis B virus-associated cirrhosis manifested various symptoms such as anemia, renal damage and neurological signs including cerebellar ataxia due to long-term administration of germanium-containing food. The patient was a 40-year-old male who had taken germanium containing mineral cheese for 26 months after he was diagnosed as having cirrhosis. Twenty four months after beginning to take the mineral cheese, he began manifesting paresthesia of the extremities, dysarthria and gait ataxia. Laboratory findings revealed anemia and renal damage. Biopsy of the peripheral nerve revealed loss of the large sheathed nerve, a characteristic feature of germanium intoxication. A high concentration of germanium (GeO2) was detected in patient's hair and urine. Cerebellar ataxia was characteristic in this patient, which was not reported in the previous papers.

Strong association of insulin autoimmune syndrome with HLA-DR4

Insulin autoimmune syndrome is characterised by spontaneous hypoglycaemia without evidence of exogenous insulin administration, a high serum concentration of total immunoreactive insulin, and the presence of insulin autoantibodies in high titre. HLA typing of 27 patients with insulin autoimmune syndrome showed that all had DR4, which was present in only 43% of 51 healthy controls (odds ratio 72.1, p less than 2 x 10(-6), and 19 (70%) of the patients were positive for the allelic combination, Cw4, Bw62, and DR4. Analysis of the nucleotide sequences of the DRB1, DQA1, and DQB1 genes showed that all the patients had DRB1*0406, DQA1*0301, and DQB1*0302, compared with only 14% of the controls (odds ratio 281, p less than 1 x 10(-10). We conclude that the development of insulin autoimmune syndrome is associated with a strong genetic predisposition.

Characterization of atrial natriuretic peptide in urine from rats treated with a neutral endopeptidase inhibitor

To explore the mechanisms for the natriuretic effects of a neutral endopeptidase inhibitor, candoxatril, the concentration of atrial natriuretic peptide (ANP) and its molecular forms in the urine of Dahl salt-sensitive (S) rats were examined. Candoxatril-induced natriuresis (+120%, p less than 0.05) was associated with a marked increase in the urinary ANP excretion (+1200%, p less than 0.05). Analysis by Sephadex G-50 gel filtration revealed that molecular weight of the major fraction of immunoreactive (ir-) ANP in the plasma of candoxatril-treated Dahl S rats was 3K, whereas that in the urine was 2.5 K. Further analysis by reverse phase high performance liquid chromatography showed that ir-ANP in the plasma of Dahl S rats was alpha-rANP (1-28), while that in the urine from rats treated with candoxatril was alpha-rANP (1-25). These results indicate that candoxatril inhibits the complete degradation of ANP in the kidney, thereby increasing the amount of biologically active ANP reaching the distal nephron and contributing to natriuresis.

Concomitant expression of receptor subtype and isopeptide of endothelin by human adrenal gland

We studied whether specific receptors for endothelin (ET) isopeptide exist in human aldosterone-producing adenoma and normal adrenal cortex, and whether ET isopeptides are produced by human adrenal gland. Competitive binding studies using [125I]ET-1 as a radioligand revealed the presence of a single class of high-affinity binding sites for ET-1 with the apparent KD of 70 +/- 31 pM and Bmax of 226 +/- 139 fmol/mg protein in adenoma membranes almost comparable to those in adjacent normal cortex. The apparent Ki for ET-2 and ET-3 were 89 +/- 33 pM and 82 +/- 16 pM, respectively. Northern blot analysis of poly(A)+ RNA of adenoma and adjacent normal cortex using cDNAs for ET receptor subtype (ETA, ETB) and ET isopeptide (ET-1, ET-3) as probes revealed that ETA and ETB receptors as well as ET isopeptides (preproET-1, preproET-3) are concomitantly expressed in both tissues. Our data demonstrate for the first time that ET receptor subtype (ETA and ETB) and ET isopeptide (ET-1 and ET-3) are concomitantly expressed by human adrenal cortex, suggesting the potential role of ETs as a local mediator in human adrenal gland.

Effects of three distinct natriuretic peptides on receptor binding and guanylate cyclase activities in rat glioma cells

Receptor binding and cyclic GMP generation by three distinct natriuretic peptides (ANP, BNP, CNP) were studied in a cultured rat glioma cell line (C6). Binding studies revealed the presence of high-affinity binding sites for three natriuretic peptides with almost comparable affinities. In contrast, CNP and BNP were almost equipotent in stimulating intracellular cyclic GMP generation over the low concentration range, but CNP caused further elevation in the high concentration range, whereas ANP was minimally effective. Our data suggest that the glioma cells possess receptors more responsive to CNP than ANP and BNP despite no apparent correlation between receptor binding affinities and cyclic GMP responses.

Human insulin-specific immunoglobulin G antibody and hypoglycemic attacks after the injection of gold thioglucose

A 56-year-old woman with granulomas of gold thioglucose in her hips exhibited recurrent bouts of hypoglycemic attacks. The first attack occurred 2 years after the last injection of gold thioglucose, when large amounts of extractable insulin and human insulin-specific antibody were noted in her serum. Histological examination of the resected granulomas showed marked infiltration of lymphocytes, plasma cells, and macrophages containing yellowish-brown granules, which proved to be gold by electron microscopy using X-ray microanalysis. After resection of the granuloma, however, the frequency of the hypoglycemic attacks decreased remarkably as well as the levels of both extractable insulin and human insulin-specific antibody.

[Clinical study of Pseudomonas aeruginosa isolated from the urine of patients with urinary tract infections]

We studied the characteristics of Pseudomonas aeruginosa isolated from the urine specimens of the patients with urinary tract infections (UTI), in the urological unit at Kitasato University Hospital, between April, 1989 and March, 1990. Pseudomonas aeruginosa was detected in 8.0% of the total urine specimens (1.1% from outpatients, 6.9% from inpatients). Serotype of Pseudomonas aeruginosa was F (33%), G (17%), M (14%) and others (36%). In sensitivity tests, imipenem (IPM) had the lowest MIC among 8 antimicrobial agents tested, which were imipenem, piperacillin, cefsulodin, ceftazidime, aztreonam, gentamicin, amikacin, and ofloxacin with 5.0%, 82.0%, 74.0%, 69.0%, 92.0%, 67.0%, 79.0% and 82.0% resistant strains, respectively. Bladder cancer was the most common underlying disease in the urological patients with Pseudomonas infection. Pseudomonas aeruginosa infection is still an annoying problem in UTI among compromised patients suffering from advanced urinary tract malignancies.

Endothelin-1- and endothelin-3-induced vasorelaxation via common generation of endothelium-derived nitric oxide

The vasorelaxant effects by endothelin-1 (ET-1) and endothelin-3 (ET-3), and their mechanisms of action were studied in isolated porcine pulmonary arterial strips. ET-1 and ET-3 dose-dependently (10(-9) - 10(-8) M) relaxed vascular strips precontracted with norepinephrine only in the presence of endothelium. The maximal vasorelaxant effect by ET-1 was about 70% of that by ET-3. The ET-1- and ET-3- induced vasorelaxation was blocked by NG-nitro-L-arginine, an inhibitor of nitric oxide synthesis, and methylene blue, an inhibitor of soluble guanylate cyclase. The present data suggest that vascular smooth muscle relaxation induced by ET-1 and ET-3 is mainly ascribed to synthesis and release of nitric oxide from L-arginine in endothelium.

Duplication mitosis in carcinoma

As proposed in 'Duplication mitosis in epithelio-glandular tissue' (1), histological continuity is dependent on duplication mitosis. Organoid continuity of carcinomas is also likely to be dependent on duplication mitosis. Cancerous duplication may be due to deterioration of the maturation capacity of carcinoma cells and caused by a cellular abnormality that rejects the effect of the maturation factor. The fundamental therapeutic approach to carcinoma should be altered from one of cell destruction to one of inducing cell-phase maturation.

Changes of circulating atrial natriuretic peptide and antidiuretic hormone in obstructive sleep apnea syndrome

Patients with obstructive sleep apnea (OSA) syndrome are known to exhibit nocturnal natriuresis/diuresis. We studied plasma and urinary levels of atrial natriuretic peptide (ANP), a potent natriuretic hormone released from the heart, and plasma antidiuretic hormone (ADH) levels in patients with OSA during awake and sleeping periods, to compare with those of normal subjects. Seven patients with OSA and 6 normal subjects were studied. Arterial blood samples were drawn during the awake and the sleeping period, while in patients with OSA, blood samples were obtained during the apneic period. Urine samples were collected over two 12-hour periods (9 a.m.-9 p.m. and 9 p.m.-9 a.m.) In patients with OSA, plasma ANP as well as urinary ANP excretion increased during the apneic period compared with the awake period. There was a significant negative correlation between plasma levels of ANP and ADH in patients with OSA. On the other hand, normal subjects had no apparent differences in plasma and urinary ANP levels between the two periods. It is suggested that nocturnal increase in ANP and decrease in ADH are responsible for the nocturnal diuresis and natriuresis associated with OSA.

Brain catecholamine concentrations in hyperosmolar diabetic and diabetic rats

The concentration of brain catecholamines were measured and compared in the experimentally made hyperosmolar diabetic, diabetic and normal control rats in order to clarify the metabolic changes of the brain in these states. Diabetes was induced with streptozotocin and hyperosmolarity was achieved through deprivation of water for 50 hours prior to experimentation. Dopamine, norepinephrine and epinephrine concentrations were measured in the left cerebral cortex, hypothalamic-thalamic area, cerebellum and medulla oblongata. Dopamine and norepinephrine concentrations were significantly elevated in the cerebral cortex, hypothalamic-thalamic area and cerebellum of the dehydrated hyperosmolar-diabetic rats relative to those of normal controls (p < 0.01-0.05). In diabetes with high blood sugar level, the norepinephrine concentration was significantly elevated in the cerebral cortex, cerebellum and medulla oblongata, and these changes generally paralleled the increase in fasting blood glucose. It was concluded that hyperosmolarity due to dehydration contributed these changes. The findings of this study further suggest that changes in brain catecholamines may be involved in the nervous system disturbances that occur in the dehydrated hyperosmolar-diabetes and severe diabetes.

An investigation of Japanese subjects maps susceptibility to type 1 (insulin-dependent) diabetes mellitus close to the DQA1 gene

Insulin-dependent diabetic and control subjects of Japanese origin were HLA-DRB1, -DQB1, and -DQA1 typed using restriction fragment length polymorphism analysis and sequence-specific oligonucleotide gene probing. The DQA1 allele DQA1*0301 was positively associated with the disease [48/52 (92%) diabetic patients versus 44/64 (69%) control subjects, Pc less than 0.03, RR = 4.97]. Alleles of the DRB1 and DQB1 genes showed no significant association with the disease. The frequency of DQB1 genotypes encoding the amino acid aspartic acid at position 57 of the DQ beta chain did not differ significantly between subjects with insulin-dependent diabetes mellitus (IDDM) and controls. These findings suggest that a susceptibility allele for IDDM in the Japanese is more closely associated with the DQA1 gene than the DQB1 gene.