Regulation of secretion and clearance of C-type natriuretic peptide in the interaction of vascular endothelial cells and smooth muscle cells

OBJECTIVE

To clarify the significance of C-type natriuretic peptide in the interaction between endothelial cells and vascular smooth muscle cells by investigating the endothelial production of C-type natriuretic peptide and the clearance mechanism of C-type natriuretic peptide using the endothelial cells-smooth muscle cells co-culture system.

RESULTS

Secretion of C-type natriuretic peptide in the direct co-culture of endothelial cells with smooth muscle cells elicited as much as a 60-fold increase compared with endothelial cells alone. The accumulation of intracellular cyclic GMP in the co-culture was consequently increased and the elevation of cyclic GMP level in the co-culture was abolished by the anti-C-type natriuretic peptide monoclonal antibody. The elevated cyclic GMP production in the co-culture was abolished by the anti-transforming growth factor-beta neutralizing antibody. Candoxatrilat (10(-6)-10(-4) mol/l), a neutral endopeptidase inhibitor, dose-dependently increased the concentrations of C-type natriuretic peptide in the culture medium with endothelial cells alone, but not in the endothelial cells-smooth muscle cells co-culture. The transcript of neutral endopeptidase messenger RNA was detected in endothelial cells but not in smooth muscle cells by reverse transcriptase polymerase chain reaction. Treatment with C-atrial natriuretic factor4-23 (10(-9)-10(-6) mol/l), the specific ligand for the clearance receptor of the natriuretic peptides, resulted in dose-dependent augmentation of C-type natriuretic peptide concentration and concomitant intracellular cyclic GMP production in the endothelial cells-smooth muscle cells co-culture but not in endothelial cells alone.

CONCLUSION

The present study demonstrated that direct interaction between endothelial cells and smooth muscle cells augments C-type natriuretic peptide secretion from endothelial cells through transforming growth factor-beta activation, and revealed that the enzymatic degradation is responsible for the steady state level of C-type natriuretic peptide in endothelial cells alone and that the receptor-mediated clearance mainly determines the augmented level of C-type natriuretic peptide in the interaction between endothelial cells and smooth muscle cells. The results taken together raise the possibility that endothelial C-type natriuretic peptide might play a role in regulation of vascular tone and remodelling.

Changes in regional cerebral blood flow during self-paced arm and finger movements. A PET study

The purpose of this study was to identify the functional fields activated in relation to the self-paced proximal and distal arm movements. The regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET) and 15O-labelled H2O (H2(15)O) in eight healthy subjects. All subjects performed the following three tasks: (1) repetitive opposition of thumb and index finger of the right hand, (2) repetitive co-contraction of biceps and tricepts brachii muscles of the right arm, and (3) rest. The mean rCBF change images for each task minus control was calculated and fields of significant rCBF changes were identified. Each movement activated different fields in the primary motor area (MI), the dorsal aspect of the premotor area (PMA) and the superior part of the prefrontal area (PFA) of the contralateral hemisphere. In these areas, arm fields were located relatively dorsally to the finger fields. In addition, specific fields in the ventral part of the PMA, the supplementary motor area (SMA), the superior parietal lobule (SPL) of the contralateral hemisphere, and the ipsilateral PFA were consistently activated during both movements. Due to a limited a field of view of the PET scanner in the axial direction, the PET scan could not cover the cerebellum. The results indicate that there may be somatotopical organization not only in the MI but also in the dorsal part of the PMA and the PFA, and that the specific fields in the ventral part of the PMA, the SMA, the SPL, and the PFA may be involved in self-paced movement.

Regulation of endothelial production of C-type natriuretic peptide in coculture with vascular smooth muscle cells. Role of the vascular natriuretic peptide system in vascular growth inhibition

Recently, we have demonstrated that C-type natriuretic peptide (CNP) is produced in vascular endothelial cells (ECs). In the present study, we investigated the interaction of ECs and vascular smooth muscle cells (SMCs) for endothelial production of CNP and its action on vascular growth, using the EC/SMC coculture system. The concentration of CNP-like immunoreactivity in the medium was increased 60-fold within 48 hours in the EC/SMC coculture with direct contact compared with that in EC alone. Northern blot analysis revealed the augmented expression of CNP mRNA in the EC/SMC coculture. The accumulation of intracellular cGMP in the coculture was concomitantly increased, and this response was blocked by anti-CNP monoclonal antibody and HS-142-1, a nonpeptide atrial natriuretic peptide receptor antagonist. The concentration of biologically active transforming growth factor-beta (TGF-beta) in the culture medium of the coculture with direct contact of ECs and SMCs was elevated to the level to stimulate endothelial production of CNP. Actually, the neutralizing antibody against TGF-beta abrogated the cGMP accumulation in the coculture. These results show that endothelial production of CNP in the EC/SMC coculture is at least in part regulated by TGF-beta. Furthermore, the conditioned medium from ECs stimulated by TGF-beta was demonstrated to have a growth-inhibitory effect on SMCs, which was abolished by anti-CNP monoclonal antibody and HS-142-1. The treatment with anti-CNP monoclonal antibody and HS-142-1 also significantly increased the cell number of the EC/SMC coculture. The present study reveals the pathophysiological significance of endothelial CNP as a paracrine/autocrine vascular regulator for vascular growth in the interaction of ECs and SMCs.

Growth of cultured human bronchiogenic epithelioid CCD-14 Br cells and dermal fibroblasts, NB1 RGB treated with ginseng tetrapeptide and its isomer

The configurations of the component amino acids in ginseng tetrapeptide 1 isolated from Panax ginseng were determined by HPLC with an optical resolution column and the structure of 1 was established to be H-L-Val-gamma-D-Glu-D-Arg- Gly-OH. Synthesis of the ginseng tetrapeptide, 1, and of the configuration and conjugation isomers, H-L-Val-gamma-L-Glu-L-Arg-Gly-OH (2), H-L-Val-D-Glu- D-Arg-Gly-OH (3), and H-L-Val-L-Glu-L-Arg-Gly-OH (4) was carried out by a solid-phase method using the Fmoc strategy. The effects of 1-4 on the proliferation of baby hamster kidney (BHK)-21 cells, normal female bronchiogenic epithelioid (CCD-14 Br) cells, and normal human epidermal fibroblast (NB1 RGB) were examined. Only 1 showed 32 and 23% enhancement of BHK-21 and human CCD-14 Br cells growth, respectively, at a concentration of 13.6 microM and 41% enhancement of NB1 RGB cells growth at a concentration of 32 microM under the conditions employed. It was shown that both the configuration of the component amino acids and the peptide conjugation at a gamma-position of D-Glu in 1 are important for proliferation of the cells. Compound 1 exerted a prominent effect on cell stimulation and growth rate without any morphological change and showed no cytotoxicity.

Radical surgery for advanced gallbladder carcinoma

Forty-four patients with advanced gallbladder carcinoma (18 with stage pT3 and 26 with stage pT4 of the Union Internacional Contra la Cancrum classification) were aggressively managed by extended heptatic resection in 33 patients, bile duct resection in 28, pancreaticoduodenectomy in seven, gastrointestinal resection in eleven and portal vein resection and reconstruction in seven. Adjacent organ involvement was classified as follows: type I, hepatic involvement with or without gastrointestinal invasion (Ia, Ib); type II, bile duct involvement with or without gastrointestinal invasion (IIa, IIb); type III, hepatic and bile duct involvement with or without gastrointestinal invasion (IIIa, IIIb); type IV, gastrointestinal involvement without hepatic or bile duct invasion. Fourteen of 15 patients with type I tumours had a curative resection compared with seven of 26 with type III lesions (P < 0.0001). The surgical mortality rate was two of 15 patients with type I tumours, seven of 26 with type III tumours and nine of 44 for the whole group. The long-term survival rate after curative resection was four and two of 23 at 3 and 5 years respectively, significantly better than two and none of 21 at 1 and 2 years after non-curative resection (P < 0.01). The survival rate after curative resection for patients with type I tumours was four and two of 14 at 3 and 5 years respectively, significantly better than for other types (P < 0.05). This classification of advanced gallbladder carcinoma according to involvement of adjacent organs might be helpful in planning surgery for this condition; in particular, type I tumours should be treated by a radical surgical procedure to achieve a favourable outcome.

Walking patterns and finger rhythm of older adults

Walking patterns and rhythmic movement of the fingers were examined in a total of 1,134 male and female community residents 65 years of age and over. Walking patterns were characterized according to the ratio of step length divided by step rate (cadence), called the Walk Ratio, during level walking at preferred and maximum speeds. The walking pattern tended to change according to age; older subjects walked with shorter steps (smaller Walk Ratio). Rhythmic movement was examined using the finger-tapping test in time to the sound of a 4-Hz metronome. Hastened tapping or finger festination, in which the subject tapped faster than requested (constant error of 3 msec. and over in the intertap interval), was characteristic of aging; 16.8% of the subjects exhibited finger festination and the occurrence increased with age, especially among those in their eighties (29.3%). Finger festination was accompanied by walking patterns with an increased step rate, or a smaller Walk Ratio. These characteristics of aging were discussed as similar to extrapyramidal symptoms of walking and rhythm production in patients with Parkinson's disease.

Diffuse ganglioneuromatosis with plexiform neurofibromas limited to the gastrointestinal tract involving a large segment of small intestine

A rare case of diffuse ganglioneuromatosis with plexiform neurofibromas limited to the gastrointestinal tract in a 20-year-old man is reported. The patient had no cafe-au-lait spots or any apparent tumorous lesions affecting other organs. A fan-shaped resection of the mesentery, including 200cm of the ileum, together with ileocecal resection was done, and the diagnosis was histologically confirmed. The relationship between this benign tumor and other neurogenic disorders is discussed, along with a review of the literature. Long-term follow up of this patient is required because of the possible development of von Recklinghausen's disease or multiple endocrine neoplasia type IIb.

Cloning of the cDNAs for mast-cell chymases from the jejunum of Mongolian gerbils, Meriones unguiculatus, and their sequence similarities with chymases expressed in the connective-tissue mast cells of mice and rats

By using the combination of reverse-transcription CR and rapid amplification of cDNA ends methods, two distinct cDNAs encoding mast-cell proteases (chymases; MCPs), designated as gMCP-1 and -2, were successfully cloned and sequenced from the jejunum of Mongolian gerbil, Meriones unguiculatus, infected with Nippostrongylus brasiliensis. On the basis of a comparison of the deduced amino acid sequences with those of known rodent mast-cell chymases, gMCP-1 was found to be highly similar to mouse mast-cell protease (mMCP)-4 and rat mast-cell protease (rMCP)-1, while gMCP-2 was similar to mMCP-5 and rMCP-3. Alghough mMCP-4 and -5 and rMCP-1 and -3 were restrictedly or mainly expressed in connective-tissue mast cells and serosal mast cells, the gMCP-1 and -2 genes were mainly transcribed in the jejunal mucosa and to a lesser extent in the skin and tongue. Moreover, kinetic study after infection revealed that the amounts of the gMCP-1 and -2 mRNAs in jejunum paralleled well the degree of intestinal mastocytosis. The expression of gMCP-1 and -2 in mucosal mast cells of gerbil jejunum was also confirmed by in situ hybridization. Since a tryptase, another type of MCP, was also expressed in mucosal mast cells of gerbils but not in those of mice and rats, the expression of MPCs in mucosal mast cells of gerbils is different from those of mice and rats. The Mongolian gerbil would be a useful model with which to investigate the physiopathological role of MCPs.

Natriuretic peptide receptors in human artery and vein and rabbit vein graft

Natriuretic peptides elicit their biological effects by elevation of cGMP through activation of two biologically active receptors: natriuretic peptide A receptor, which shows high affinity to atrial and brain natriuretic peptides, and natriuretic peptide B receptor, which is specific to C-type natriuretic peptide. To elucidate the implications of the natriuretic peptide system in arteries and veins, we examined the cGMP production in response to atrial and C-type natriuretic peptide and gene expressions of biologically active natriuretic peptide receptors in human gastroepiploic artery, internal mammary artery, and saphenous vein. Atrial natriuretic peptide augmented cGMP production more potently by one order of magnitude in arteries than in veins. C-type natriuretic peptide stimulated cGMP production weakly and equally in these vessels. Analyzed by reverse transcription-polymerase chain reaction, gene expression of natriuretic peptide A receptor was four times more abundant in arteries than in veins. Gene expression of natriuretic peptide B receptor was approximately the same between these vessels. We also studied the responsiveness to atrial and C-type natriuretic peptide in rabbit jugular vein grafted into carotid artery. In arterialized vein grafts 4 weeks after operation, the effects of atrial and C-type natriuretic peptides on cGMP production did not change from those in jugular veins. In conclusion, atrial natriuretic peptide stimulates cGMP production more potently in arteries than in veins due to the preferential expression of natriuretic peptide A receptor in arteries. These observations support the distinct roles of natriuretic peptides in cardiovascular homeostasis.

Vascular endothelial growth factor suppresses C-type natriuretic peptide secretion

Angiogenesis plays a pivotal role not only in wound healing and tumor progression but also in diabetic angiopathy, arteriosclerosis, and collateral formation of obstructive vascular diseases. Vascular endothelial growth factor (VEGF) is now thought to be an endothelium-specific and potent angiogenic factor. We previously demonstrated that C-type natriuretic peptide (CNP), originally isolated from porcine brain, is produced by endothelial cells and proposed that CNP can exert control over vascular tone and growth as a local vascular regulator. In the present study, we examined the effect of VEGF on CNP secretion from endothelial cells using the specific radioimmunoassay for CNP we developed. VEGF (1 to 100 ng/mL) dose-dependently suppressed CNP secretion from cultured bovine endothelial cells, and 100 ng/mL VEGF suppressed endothelial CNP secretion to 28% of control levels (31.7 +/- 5.5 versus 8.9 +/- 0.8 fmol/mL, vehicle versus VEGF). VEGF also suppressed CNP mRNA expression in endothelial cells 9 hours after administration. In contrast, basic fibroblast growth factor (20 ng/mL), an endothelium-nonspecific angiogenic factor, significantly stimulated CNP secretion by 290%. These results indicate that VEGF can regulate vascular tone and growth in the process of angiogenesis through suppression of endothelial secretion of CNP, which is an endothelium-derived vasorelaxing and growth-inhibitory peptide.

[Changes in plasma level of brain natriuretic peptide during exercise in recovery phase of myocardial infarction and the clinical significance]

Brain natriuretic peptide (BNP) plasma levels increase in patients with myocardial infarction and may reflect the degree of left ventricular dysfunction. The changes in plasma level of BNP during exercise in the recovery phase and the clinical significance were investigated in 60 patients (55 men and 5 women; mean age 62.3 +/- 9.8 years) with initial acute infarction. Cardiopulmonary exercise testing was performed with a treadmill using the ramp protocol in 60 patients in the first month and 46 in the third month after the onset of the disease. Blood samples for measuring BNP and atrial natriuretic peptide (ANP) were obtained in the resting control state and immediately after peak exercise. Plasma BNP in the first month had a significant negative correlation with anaerobic threshold (AT) and peak oxygen uptake (peak VO2), and the serial change in plasma BNP from the first to third month had a significant negative correlation with the serial change of AT (peak: r = -0.35, p < 0.05) and peak VO2 (rest: r = -0.35, p < 0.05; peak: r = -0.45, p < 0.01). The serial change of plasma ANP had no relationships with the serial change of AT or peak VO2. Because the serial change ratio of plasma BNP reflects the serial change of exercise tolerance in the recovery phase of myocardial infarction, we conclude that the serial measurement of plasma BNP level is a useful non-invasive parameter for predicting latent heart failure in patients with myocardial infarction.

cDNA cloning and gene expression of human type Ialpha cGMP-dependent protein kinase

The type I cGMP-dependent protein kinase (cGK) is one of the major pathways for the cGMP cascade and has been demonstrated to inhibit platelet aggregation, relax smooth muscle cells, and control cardiocyte contractility. There are two subtypes of the type I cGK, cGKIalpha and cGKIbeta. The former is more sensitive to cGMP than the latter. In humans, cGKIbeta cDNA was isolated, but the full structure and tissue-specific gene expression of cGKIalpha have not been determined. The significance of cGK in human cardiovascular diseases has not been investigated at the molecular level. In the present study, we isolated the full-length human CGKIalpha cDNA (-36 to +2177; the translation start site: +1) enclosing the 671-amino acid protein. Nucleotides +267 to +2177 of the isolated cDNA were identical to the corresponding nucleotides of human cGKIbeta cDNA. Southern blot analysis suggested that human cGKIalpha and cGKIbeta are generated by alternative splicing of a single gene assigned to chromosome 10. By Northern blot analysis, we detected abundant human cGKIalpha mRNA (7.0 kb) in the aorta, heart, kidneys, and adrenals. In contrast, human cGKIbeta mRNA (7.0 kb) was detected abundantly only in the uterus. In cultured vascular smooth muscle cells, the type I cGK mRNA concentration was reduced to 10% of the basal level by 4 x 10(-10) mol/L platelet-derived growth factor. Angiotensin II (10(-8) mol/L), transforming growth factor-beta (4 x 10(-11) mol/L), and tumor necrosis factor-alpha (6 x 10(-6) mol/L) also exhibited an inhibitory effect on type I cGK gene expression. These findings suggest a pathophysiological implication of the type I cGK in cardiovascular diseases, including hypertension and atherosclerosis.

Increased induction of apoptosis of human colorectal cancer cells after preoperative treatment with 5-fluorouracil

We examined whether the administration of 5-fluorouracil (5-FU) could enhance apoptosis of colorectal cancer cells, and we investigated the relationship between apoptosis and the expression of Ki-67, p53, and c-myc. Twenty patients with advanced colorectal cancer were divided into two groups. Ten received continuous intravenous 5-FU at 500 mg/body/day for 7 days preoperatively and 10 did not receive 5-FU and served as controls. Apoptotic cells were stained by so-called TUNEL method (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling). Apoptosis of cancer cells increased significantly to 18+/-6% in the 5-FU-treated group as compared to the controls (3+/-1%; p<0.001). Expression of Ki-67, a indicator of cell proliferation, was inversely correlated with the TUNEL staining that was specific for apoptosis and the percentage of cells immunostained for Ki-67 fell significantly to 34+/-14% of the apoptotic area as compared to 72+/-12% in controls (p<0.001). There was no clear correlation between expression of apoptosis and the expression of p53 or c-myc.

Purification, characterization and molecular cloning of Cha o 1, a major allergen of Chamaecyparis obtusa (Japanese cypress) pollen

Pollen of Chamaecyparis obtusa (Japanese cypress) is one of the causes of allergic pollinosis in Japan. A major allergen of the pollen designated Cha o 1, was purified by two-step ion exchange chromatography. Cha o 1 was separated into four components with molecular masses of 48.5 kDa and 52.0 kDa, each with pIs of 6.77 and 6.82. The 23-residue N-terminal sequence of Cha o 1 was determined and shown to have high identity with that of Cry j 1, a major allergen of Cryptomeria japonica pollen. cDNA coding for Cha o 1 was cloned by hybridization screening using Cry j 1 cDNA as a probe. One of the cDNA clones, pCHA-1 was sequenced and found to code for a putative 21-residue signal peptide and a 354-residue native protein with a derived molecular mass of 38.1 kDa. The deduced amino acid sequence of Cha o 1 showed 79-80% identity with those of Cry j 1. These findings were consistent with observations of a close crossreaction between the two allergens. Homology analyses revealed that Cha o 1 had 46-49% identity with Amb a 1 families and Amb a 2, the major allergens of short ragweed. Cry j 1 has pectate lyase enzyme activity, suggesting that Cha o 1 may have the same enzyme activity as Cry j 1.

Severe neonatal nemaline myopathy with delayed maturation of muscle

A Japanese infant with a severe neonatal form of nemaline myopathy showed features of muscle immaturity as well as rods in the biopsied quadriceps femoris muscle, and involvement of diaphragm was first confirmed at autopsy. The biopsied muscle showed numerous rods in 80% of muscle fibers, and an increased number of type 2C fibers (23.2%). Electron microscopic findings were characterized by the presence of many small, immature round fibers with central nuclei and sparse myofibrils, and an increased number of satellite cells in close association with the small muscle fibers, as well as numerous rod structures. These microscopic and electron microscopic findings are interpreted as immature muscle fibers. Maturational delay or arrest implies deprivation of a development promoting factor such as a neuronal signal. Severe involvement with numerous rods was demonstrated in both diaphragm and intercostal muscles at the time of the postmortem examination, compatible with the patient's respiratory failure.

In vitro analysis of peritoneal adhesions in peritonitis

Peritoneal adhesions due to peritonitis make surgery more difficult and may cause complications. Clarifying the formation mechanism of peritoneal adhesions could help identify methods useful for their prevention. We cultured mesothelial monolayers on plates and microcarriers to simulate the parietal and visceral peritoneum, respectively. We then investigated the effects of lipopolysacchride (LPS) and tumor necrosis factor (TNF) on the homologous adhesion of these mesothelial monolayers. There was no adhesion of mesothelial monolayers in the control medium. When monolayers were cultured with endotoxin (LPS), approximately 90% of the microcarriers adhered to the mesothelial microplate. Adhesions occurred at LPS concentrations of 10 ng/ml and increased linearly in a dose-dependent manner. Kinetic studies revealed that the mesothelial adhesion appeared at 12 hr, and that 90% of the microcarriers were adherent after 24 hr. Open intercellular spaces were observed after a 24-hr treatment with LPS. Scanning electron microscopy revealed that the mesothelial cells adhered to the naked glass. LPS also caused increased permeability of the mesothelial monolayer. TNF did not cause any significant adhesion. Through our experiments we were able to develop an in vitro model of peritoneal adhesion using peritoneal mesothelial cell culture. Endotoxin caused an increase in homologous adhesion of peritoneal mesothelial monolayers, which may correspond to the initial stage of peritoneal adhesion formation in peritonitis.

[Progressive stroke during the acute state of cerebral infarction in the territory of the internal carotid artery]

Diagnosis of deterioration of neurological deficits in the early stage after hospital admission immediately after the onset of cerebral infarction is important in establishing a treatment plan. This study investigated the clinical characteristics of progressive stroke on admission. The subjects were 309 patients admitted on the day of the onset of symptoms and showed a low density area on CT images within 5 days. There were 202 with cerebral infarction in the territory of the deep perforate arteries, 77 with cerebral infarction in the territory of the cortical branch of the middle cerebral artery (MCA), and the remaining 36 had cerebral infarction in the territory of MCA. The results were as follows: 1) Progressive stroke was observed in 71 patients (23.0%): 60 with completed stroke and 11 with reversible ischemic neurological deficits (RIND). 2) The patients with progressive stroke were clearly older than those with non progressive stroke (p < 0.05: Cochran Cox's test). 3) Progressive stroke was seen more frequently in patients with cerebral infarction of the cortical branch of the MCA and patients with occlusion of the internal carotid artery and MCA trunk than patients with cerebral infarction of the deep perforate arteries (p < 0.001: chi 2 test). 4) All patients with progressive stroke had initial evidence of deterioration of neurological deficits within 5 days after the onset, with 39 patients showing deterioration on day 2 and 13 patients showing deterioration on day 3. 5) Deterioration of neurological deficits usually stopped the day after the start of progression. The maximum period from the beginning to the end of the deterioration of neurological deficits was 7 days. 6) Progressive stroke was not seen in 11 patients who were admitted with higher cortical dysfunction and without sensory or motor disturbances, and was seen in only 8 (4%) of the 187 patients with sensory or motor disturbances without higher cortical dysfunction. 7) Progressive stroke was seen in 63 (57%) patients with sensory or motor disturbances and higher cortical dysfunction. 8) Progressive stroke was seen frequently in patients with atrial fibrillation (Af) on the ECG [P < 0.001). 9) Fifty-six of 71 patients with progressive stroke showed persistent severe motor impairment in the upper limbs. Therefore, to diagnose progressive stroke, it is useful to assess the higher cortical dysfunction and examine for Af on admission.

Alternative RNA splicing of the human endothelin-A receptor generates multiple transcripts

In order to elucidate the regulatory mechanisms of expression of the human endothelin-A receptor (hET-AR) gene, we characterized hET-AR transcripts using reverse transcriptase (RT)-PCR analysis in a variety of human tissues. RT-PCR of lung mRNA using a set of primers from exons 2 and 5 showed two lower-molecular-mass transcripts in addition to the expected fragment. When RT-PCR with primers from exons 4 and 8 was performed, no transcripts other than the expected one were detected. PCR cloning utilizing a set of primers from exons 2 and 8 which covered the entire coding sequence revealed that the cDNA clones corresponding to the two novel transcripts contained deletions of 199 bp and 327 bp respectively compared with the previously described hET-AR cDNA. Comparison of their sequences with that of the hET-AR gene showed that the deleted sequences correspond exactly to exon 4 and exons 3 and 4 respectively, indicating that these lower-molecular-mass ET-AR transcripts results from alternative RNA splicing (designated ET-AR delta 4 and ET-AR delta 3,4 respectively). Alternative splicing of exon 4 results in a transcript which would be translated into a C-terminal truncated protein containing the first, second and third transmembrane domains, while the splicing out of exons 3 and 4 would produce a protein with five membrane-spanning domains but lacking the third and fourth domains present in the ET-AR protein. An RNase protection assay revealed that ET-AR delta 4 and ET-AR delta 3,4 as well as ET-AR, transcripts were observed in various human tissues, including the lung, aorta, atrium, kidney and placenta, which are known to express ET-AR abundantly. Thus we have isolated the cDNAs of novel transcripts of hET-AR which are generated by alternative RNA splicing, and these results suggest that this alternative RNA splicing might contribute to the regulation of ET-AR gene expression.

Blood pressure at health screening as a predictor of coronary heart disease in Kyoto

AIM

Most epidemiologic studies that have evaluated coronary risk factors have measured either mortality or morbidity of coronary artery disease (CAD) as endpoints. However, earlier detection and elimination of coronary risk factors are crucial. We therefore performed Master's double (i.e. 1.5 min x 2 = 3 min) two-step exercise electrocardiograph (ECG) test in apparently healthy asymptomatic subjects (men, n = 2274; women, n = 959) to elucidate the risk factors for early-stage CAD or silent myocardial ischemia.

METHODS

We examined the possible association of blood pressure at health screening and other suspected risk factors with exercise ECG test performance. The ischemic ECG response was determined by (1) > or = 0.5 mm horizontal or sagging S-T segment depression, (2) > or = 2.0 mm J-shaped S-T segment depression, or (3) T inversion in post-exercise ECG.

RESULTS

We found that 4.7% of men and 10.6% of women exhibited ischemic responses. Among males, the ischemic responders to the exercise ECG test had higher systolic and diastolic blood pressure. In addition, the male ischemic responders were older, had a higher obesity index, higher serum cholesterol, triglyceride, low-density lipoprotein (LDL)-cholesterol, protein, glucose, and uric acid levels, and a lower serum potassium level than normal responders. In contrast, the female ischemic responders to the exercise ECG test had higher systolic pressure, and higher serum cholesterol, LDL-cholesterol, and protein levels than normal responders. Mean blood pressure was correlated positively with most of the other coronary risk factors, and mild hypertensives and hypertensives had abnormal lipid, glucose, and uric acid levels in both sexes. A comparison of risk factors by age group revealed that only younger and middle-aged ischemic responders had higher blood pressure, serum cholesterol, and glucose levels than normal responders of both sexes, and that in older subjects all the differences between normal and ischemic responders became insignificant.

CONCLUSIONS

Elevated blood pressure at health screening, together with abnormal lipid and glucose metabolism, might be risk factors predicting early-stage or silent CAD. The elimination of these risk factors in younger men and women seems to be important.

Does combined therapy of Ca-channel blocker and angiotensin converting enzyme inhibitor exceed monotherapy in renal protection against hypertensive injury in rats?

Either calcium channel blocker (CCB) or angiotensin converting enzyme inhibitor (ACEi) is used as an antihypertensive agent, and we are recommended to use them in combination to refractory hypertension with evidence dependent on clinical observations. We examined the renal protective effect of the combined therapy with calcium channel blocker (amlodipine) and angiotensin converting enzyme inhibitor (enalapril) against hypertensive renal injury in 5/6 nephrectomized spontaneously hypertensive rats (SHRs) with salt loading, comparing with monotherapy of each drug. Forty males SHRs with 5/6 nephrectomy and salt loading were divided to five groups: group 1 as control (n = 8), group 2 received 0.2 mg/kg/day of amlodipine (n = 8), group 3 received 0.2 mg/kg/day of enalapril (n = 8), group 4 (n = 8) and group 5 (n = 8) that were treated with 0.1 mg/kg/day and 0.2 mg/kg/day of each drug in combination respectively. Either amlodipine or enalapril had remarkable effects on reducing the increases in blood pressure and urinary protein excretion. In histopathological examination, it also suppressed renal injury significantly. Additional significant effect of combined therapy was not observed in blood pressure and urinary protein. There were not remarkable, additional effects of the combination of CCB and ACEi on protecting the remnant kidney in 5/6 nephrectomized SHRs fed a high-salt diet, possibly because sodium retention was not alleviated by the combination.

Reversed-phase HPLC separation of proteins on chemically bonded silica gel columns

Reversed-phase high-performance liquid chromatographic (RP-HPLC) separation of proteins on chemically bonded silica gel columns is described. Efficiency of nonporous alkylsilyl bonded silica gel is compared with that of a macroporous gel that has been widely used for the purpose. A comparative study of the separation under conventional and fast separation conditions is also given. The fast separation technique on the nonporous reversed-phase column has the advantage of improving the recovery of late-eluting hydrophobic and large proteins, such as ovalbumin and apoferritin.

Immunocytochemistry of perinatal rat livers with a special reference to the roles of mesenchymal cells in hepatic differentiation

To investigate the roles of extracellular matrix produced by hepatic mesenchymal cells in the organization of hepatic cell cords, perinatal rat livers were examined with immunocytochemistry of fibronectin (FN) and laminin (LM). Some hepatocytes in a free state at prenatal day 15 actively produced FN and LM in the rough endoplasmic reticulum but lost this synthetic activity when such cells were incorporated into hepatic cell cords. On the other hand, hepatic mesenchymal cells, especially those associated with the perisinusoidal space, retained this synthetic activity throughout the stages examined. In the differentiating hepatic cell cords, positive immunoreactions for FN and LM were preferentially seen on the cell surface facing both sinusoidal space and differentiating bile canaliculus concomitant with the expression of the tight junction protein, ZO-1, from prenatal day 17. Since such hepatocytes have lost or reduced their synthetic activities of both glycoproteins in the rER, the immunoreactions appear to be mainly due to hepatic mesenchymal cells which seem to play a role in the formation of the hepatic cell cords and the bile canaliculi.