Circulating levels of endothelin and atrial natriuretic factor during postnatal life

We determined plasma endothelin-1-like immunoreactivity and atrial natriuretic factor concentrations in preterm and full-term newborn infants during the first month of life. Plasma endothelin-1-like immunoreactivity levels were far greater than those of maternal blood in the newborn infants. The highest plasma endothelin-1-like immunoreactivity levels were observed on the first day of life (8.7 +/- 3.7 pmol/l) and gradually decreased with age. There was no significant difference in plasma endothelin-1-like immunoreactivity levels between preterm and full-term infants. A good correlation was observed between plasma endothelin-1-like immunoreactivity levels and atrial natriuretic factor concentrations (p < 0.01). These results suggest that circulating endothelin may regulate the cardiovascular system in the newborn period.

Urinary arginine vasopressin excretion and hyponatremia in the sick neonates

We attempted to clarify the renal physiologic response to arginine vasopressin (AVP) in the 12 sick neonates: three with respiratory distress syndrome (RDS), three with meconium aspiration syndrome, two with transient tachypnea of the newborn, two with neonatal asphyxia, and two low birthweight infants during the first 2 days of life. Plasma atrial natriuretic factor (ANF), urinary AVP, osmolality, free water clearance and creatinine clearance (Ccr) were measured at 8 to 16 hours of life (stage 1) and 24 to 32 hours of life (stage 2). Urinary AVP was expressed as the ratio of AVP to Ccr (urine AVP/Ccr). These subjects were divided into two groups: group A represented five infants with a urine AVP/Ccr ratio of 2000 or higher and group B, seven infants with a ratio of less than 2000 at stage 1. Hyponatremia occurred in two infants of group A at stage 2. Number of infants on mechanical ventilation was four in group A and one in group B. There were no significant differences in gestational age, birthweight, Apgar scores at 1 and 5 minutes, blood gas pH and mean arterial blood pressure between groups A and B. A good correlation was observed between logarithm of urine AVP/Ccr ratio and urinary osmolality (p < 0.01). A negative correlation was observed between logarithm of urine AVP/Ccr ratio and free water clearance (p < 0.01). Body weight of infants of group A at stage 2 was greater than at stage 1 (p < 0.05). Higher plasma ANF concentrations were observed in infants of group A at stage 2 when compared with those at stage 1 (p < 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Arterial thrombosis model with photochemical reaction in guinea-pig and its property

We have already developed an arterial thrombosis model in the rat femoral artery which utilized photochemical reaction between systemically injected rose bengal and transillumination of a green light with 540 nm wave length from the outside of the vessel. In the present study, we applied this model to guinea-pigs in order to produce a more suitable thrombus model for evaluation of antithrombotic drugs which act on the prostaglandin cascade. In the guinea-pigs, the irradiated femoral artery was completely occluded in 7 min after the injection of rose bengal (10 mg/kg) in a similar manner to the rats. The processes of primary endothelial injury and the subsequent formation of thrombus during this manipulation were observed by the electron microscopy. Pretreatment with aspirin and Y-20811, a thromboxane synthetase inhibitor, significantly prolonged the time required for occlusion in the guinea-pigs, while these drugs were ineffective in the rats. The antithrombotic effect of vapiprost, a thromboxane A2 receptor antagonist, was more pronounced in the guinea-pigs than the rats. In conclusion, this model in guinea-pigs is more suitable for evaluating antithrombotic drugs, particularly, the action of which is exerted involving the prostaglandin cascade.

New method of detecting nitric oxide production

Nitric oxide (NO) reacts with H2O2 to produce a rise in potent luminol-dependent chemiluminescence under neutral pH conditions. We applied this reaction to the continuous detection of NO released from the rat isolated perfused kidney with simultaneous pressure changes. Acetylcholine increased NO release dose-dependently with the pressure reduction. An NO synthesis inhibitor, NG-monomethyl-L-arginine, abolished the release. This inhibition was reversed by the addition of L-arginine.

[Effective continuous hemofiltration and plasma exchange for the treatment of subacute type fulminant hepatic failure]

By combination of continuous hemofiltration (CHF) with plasma exchange therapy we successfully treated a patient with subacute type fulminant hepatitis to keep her consciousness alert. The patient was a 55-year-old woman who admitted because of severe jaundice. On the 51st day after the onset she had consciousness disturbance and was transferred to our hospital. We started the therapy of CHF and plasma exchange at the patient's hepatic coma grade 4. On the 5th day her consciousness level recovered to grade 2 and we could keep the level for almost 2 weeks. This combination therapy seemed good not only for the improvement of consciousness of patients in hepatic coma but also to support the hepatic function of almost ahepatic patients.

The role of endothelin-1 in the origin of cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage

Plasma and cerebrospinal fluid (CSF) endothelin (ET)-1-like immunoactivity in 27 patients with aneurysmal subarachnoid hemorrhage (SAH) was measured serially by radioimmunoassay for 2 weeks after SAH onset. Mean ET-1-like immunoactivity levels in plasma of patients with SAH were highly elevated during the whole study period, while the levels in CSF of the same patients were not. Plasma ET-1-like immunoactivity levels in patients with SAH classified as Fisher computerized tomography (CT) Group 3 were higher than those in patients with SAH classified as Fisher CT Groups 1 and 2. There were no significant differences in plasma ET-1-like immunoactivity levels between the patient groups stratified by Hunt and Kosnik grade. In this series, plasma ET-1-like immunoactivity levels in the 12 patients with vasospasm were higher than those in the 15 patients without vasospasm during the 1st week; CSF ET-1-like immunoactivity levels in patients with vasospasm were in the normal range on Days 0 to 3 after SAH onset, then became elevated on Days 5 to 7 and remained high until the end of the 2nd week. In contrast, CSF ET-1-like immunoactivity levels in patients without vasospasm were within the normal range during the entire period of study. The time course of the occurrence of vasospasm and that of the increase in CSF ET-1-like immunoactivity coincided precisely. The possible role of endogenous ET-1 in the pathogenesis of vasospasm due to SAH is discussed.

Direct effect of endothelin-1 on the granuloma cells of the porcine ovary

Specific binding sites for endothelin-1 (ET-1), a novel potent vasoconstrictor peptide, as well as the effects of ET-1 on cytosolic free Ca2+ concentration ([Ca2+]i), intracellular total inositol phosphate (IP) generation and steroidogenesis were studied in cultured porcine granulosa cells. Scatchard analysis of a binding study using 125I-labelled ET-1 indicated the presence of a single class of high-affinity binding sites with almost equal affinity for ET-1 and ET-3: the apparent dissociation constant was 0.59 nmol/l and the maximal binding capacity was 1.84 pmol/mg protein. Affinity-labelling of 125I-labelled ET-1 to the membranes using disuccinimidyl tartarate as a cross-linker revealed one major and one minor band with the apparent molecular weights of 32 kDa and 49 kDa respectively. ET-1 dose-dependently (1-100 nmol/l) induced rapid and transient increases in [Ca2+]i in fura-2-labelled cells. ET-1 also dose-dependently stimulated total IPs in cells prelabelled with myo-[3H]inositol. ET-1 had a slight stimulatory effect on the secretion of progesterone but not of oestradiol from porcine granulosa cells. The present data clearly demonstrate the presence of a non-selective ET receptor (ETB) in porcine granulosa cells coupled with phosphoinositide hydrolysis and [Ca2+]i mobilization, and suggest that ET-1 may play some role in the production of progesterone by porcine granulosa cells.

Low intermale aggression associated with small submandibular and preputial glands in goldthioglucose-obese mice

Goldthioglucose (GTG)-induced obese mice exhibited lower intermale aggression against an unfamiliar mouse, and had smaller submandibular and preputial glands than lean controls. The GTG-treated mice, which were pair-grown with control mice, also showed the same abnormalities. Therefore, obesity itself was not the cause of these abnormalities. One-h cohabitation with an unfamiliar mouse reduced the number of granules in the granular convoluted tubules of the submandibular glands of control mice. This histological change was not observed in the GTG-obese glands. These results suggest that the absence of typical intraspecific social behavior in male GTG-obese mice was associated with the failure to release a factor or factors from the submandibular glands.

Plasma alpha-human atrial natriuretic peptide concentration in patients with acute lung injury

To elucidate the pathophysiologic role of alpha-human atrial natriuretic peptide (alpha-hANP) in acute lung injury, plasma alpha-hANP concentrations were measured in 15 patients with severe lung injury, and the relationships of plasma alpha-hANP levels to the severity of lung injury, diuresis/natriuresis, and fluid balance were examined. The mean concentrations of plasma alpha-hANP (188.0 +/- 94.6 pg/ml) in patients with severe lung injury at the entry into the study were significantly (p less than 0.001) higher than those in normal subjects (31.7 +/- 12.0 pg/ml). Plasma alpha-hANP levels decreased in parallel with the improvement of lung injury in nine of 15 patients, whereas they changed little, if any, in the patients who did not recover. Plasma alpha-hANP concentrations correlated positively with urine volume, urinary sodium excretion, and excreted fraction of filtered sodium, but they correlated negatively with fluid balance at the onset of the disease as well as during the clinical course. It is suggested that elevation of circulatory alpha-hANP may reflect an adaptative mechanism to remove excessive fluid retention and reduce pulmonary hypertension for acute lung injury.

Role of endogenous ANP in sodium excretion in rats with experimental pulmonary hypertension

To explore the roles of endogenous atrial natriuretic peptide (ANP) in the volume regulation, we examined effects of antiserum for ANP or a neutral endopeptidase inhibitor, thiorphan, in rats with monocrotaline (MCT)-induced pulmonary hypertension. ANP concentrations in the plasma and right ventricle and ANP mRNA in the right ventricle of MCT-treated rats were higher than in vehicle-treated rats. The administration of the ANP antiserum into the MCT-treated rats did not affect the right atrial pressure or blood pressure but significantly decreased urinary excretion of Na by 60%. No decrease occurred in the control rats. Thiorphan dose dependently increased the urinary excretion of Na by 140% without influencing the right atrial pressure or blood pressure. This natriuresis was associated with 50 and 450% increases in ANP concentrations in the plasma and urine, respectively. The degrees of increases in urinary Na excretion, ANP, and guanosine 3',5'-cyclic monophosphate were significantly greater in the MCT-treated rats than in the control rats. Thus an increased secretion of ANP in pulmonary hypertension actually contributes to Na excretion. The augmentation of endogenous ANP activity may further potentiate the compensatory role of this peptide in the regulation of body fluid volume.

Induction of endothelin-1 gene by angiotensin and vasopressin in endothelial cells

To elucidate the cellular mechanism of endothelin-1 biosynthesis induced by angiotensin and vasopressin, we first cloned and sequenced full-length bovine preproendothelin-1 complementary DNA (cDNA) from a cultured bovine carotid artery endothelial cell cDNA library. The predicted bovine preproendothelin-1 consists of 202 amino acid residues and has a high percentage of homology to human, porcine, and rat preproendothelin-1 (70%, 81%, and 77%, respectively). Big endothelin-1, an intermediate form, consists of 39 residues differing only at position Val28 from porcine (Ile28) and His27 from rat (Arg27). The predicted 21-residue mature endothelin-1 is identical to human, porcine, rat, canine, and mouse endothelin-1. Northern blot analysis with the cloned cDNA as a probe demonstrated that a single 2.3-kb preproendothelin-1 messenger RNA (mRNA) is expressed not only in endothelial cells, but also in various bovine tissues, including lung, brain, heart, intestine, kidney, ovary, and urinary bladder. Angiotensin II and arginine vasopressin immediately and dose-dependently induced expression of preproendothelin-1 mRNA, whose effects were abolished by specific receptor antagonists. These findings suggest that stimulation of endothelin-1 secretion from endothelial cells by both agonists may be principally due to induction of preproendothelin-1 mRNA.

Effect of atrial natriuretic factor (ANF) on water homeostasis of the neonate

Atrial natriuretic factor (ANF) has been well known as a potent natriuretic peptide. The purpose of this study was to clarify the physiological role of ANF in neonates. We designed two types of study to investigate the role of ANF in neonates. (i) The role of ANF in neonatal fluid homeostasis; (ii) ANF and spontaneous diuresis. As a result, ANF may be released to control the extracellular volume and may have a role in the complex mechanisms that regulate the water homeostasis in neonates.

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.