Activation of mitogen-activated protein kinase and its activator by ras in intact cells and in a cell-free system

Mitogen-activated protein (MAP) kinase is a serine/threonine kinase whose function is thought to be essential for the transduction of mitogenic signals. MAP kinase is activated by phosphorylation induced by a variety of extracellular stimuli, and its direct upstream activator has been identified. Using amphibian and mammalian systems, we show here that ras can activate MAP kinase and its activator. Injection of v-Ha-ras p21 into Xenopus immature oocytes activated both MAP kinase and maturation-promoting factor (MPF) activities. The activation of MAP kinase preceded that of MPF, demonstrating that ras activates MAP kinase in an MPF-independent pathway. Moreover, we found that the MAP kinase activator is also activated in ras-injected oocytes. Activation of MAP kinase and its activator occurred also when the v-Ki-ras gene was conditionally induced in rat fibroblastic 3Y1 cells. Furthermore, we observed that ras activated MAP kinase and its activator in a cell-free system prepared from Xenopus oocytes. Using an antibody against the Xenopus 45-kDa MAP kinase activator, we demonstrated that the 45-kDa activator molecule was activated by ras. These findings suggest that the MAP kinase activator/MAP kinase system may be the downstream components of ras signal transduction pathways.

Cyclooctatin, a new inhibitor of lysophospholipase, produced by Streptomyces melanosporofaciens MI614-43F2. Taxonomy, production, isolation, physico-chemical properties and biological activities

Cyclooctatin has been isolated from Streptomyces melanosporofaciens MI614-43F2 as part of a program designed to find microorganism-produced inhibitors of lysophospholipase. It was purified by chromatography on silica gel, Capcell Pak C18 (HPLC) and Sephadex LH-20 followed by solvent extraction and then isolated as a colorless powder. Cyclooctatin has the molecular formula of C20H34O3. It is competitive with the substrate, and the inhibition constant (Ki) was 4.8 x 10(-6) M.

smg/rap1/Krev-1 p21s inhibit the signal pathway to the c-fos promoter/enhancer from c-Ki-ras p21 but not from c-raf-1 kinase in NIH3T3 cells

smg/rap1A/Krev-1 p21 cDNA is known to inhibit v-Ki-ras p21-induced cell transformation in NIH3T3 cells, but the inhibitory mechanism is not clear at present. In the present study, we examined the effect of smg p21s on the c-fos promoter/enhancer linked to the luciferase reporter gene (c-fos-luciferase). After transfection of c-fos-luciferase into NIH3T3 cells constitutively expressing c-Ki-ras(val-12) p21 or activated c-raf-1 kinase, expression of c-fos-luciferase was much higher than after transfection into control NIH3T3 cells. Addition of platelet-derived growth factor (PDGF), 12-O-tetradecanoyl phorbol 13-acetate (TPA) or dibutyryl cyclic AMP (Bt2cAMP) to the control NIH3T3 cells stimulated c-fos-luciferase expression. Transfection of the smg p21 cDNAs inhibited the activated ras p21-, PDGF- or TPA-stimulated c-fos-luciferase expression, but did not inhibit the activated c-raf-1 kinase- or Bt2cAMP-stimulated reaction. These results indicate that smg p21s inhibit the signal pathways from the PDGF receptor, protein kinase C, and ras p21s to the c-fos promoter/enhancer, but not those from c-raf-1 kinase and cyclic AMP-dependent protein kinase to the c-fos promoter/enhancer.

Effect of body positions and splints in bioelectrical impedance analysis

The objective of this study was to evaluate body composition as measured by bioelectric impedance analysis using splints and body positions differing from the standard supine position. Forty-three patients, randomized into two groups of different body positions, and 101 healthy volunteers were prospectively studied. Resistance and reactance of body tissues were measured by bioelectric impedance analysis. Body composition is described by a three-compartment model composed of body fat, body cell mass, and extra cellular mass. The patients were measured in the standard supine position and then randomized into two groups. They were then remeasured with the appropriate splinting device or position change. Volunteers were measured in the standard supine position and all four alternative positions. There was a statistically significant difference demonstrated in whole body resistance, whole body reactance, body cell mass, and the ratio of extracellular mass to body cell mass in some body positions. The percentage of change with different body positions and splints, when compared with the standard supine position, was generally below 2%, a clinically insignificant difference. We conclude that the reliability of resistance and reactance as measured by bioelectric impedance analysis is clinically valid using any of the tested body positions and/or splints. The three-compartment model may be a useful concept to measure body composition changes in both healthy and sick persons.

Effect of a phorbol ester on immunoreactive endothelin-1 release from cultured porcine aortic endothelial cells

This study was designed to examine how protein kinase C (PKC) regulates the release of endothelin-1 (ET-1) from cultured porcine aortic endothelial cells. We measured the release of immunoreactive (IR)-ET-1 from cells cultured for up to 72 h in the presence or absence of a phorbol ester TPA. The release of IR-ET-1 from control cells (no TPA) increased according to time for up to 72 h. In the presence of TPA, the release of IR-ET-1 from the cells was higher than the control level for up to 8 h, but was lower thereafter and reached a plateau after 48 h. TPA dose-dependently stimulated IR-ET-1 release during incubation for 4 h, but suppressed it after incubation for 72 h. Stimulation of PKC by diacylglycerol mimicked the early (4 h) action of TPA. On the other hand, pretreatment of cells with TPA to downregulate PKC significantly suppressed basal and thrombin- or FCS-stimulated IR-ET-1 release. These findings suggest that the activation of PKC is related to the stimulation of ET-1 release and that down-regulation of PKC leads to the suppression of ET-1 release from cultured endothelial cells.

Differential expression of three CD45 alternative structures on murine T cells: exon 6-dependent epitope as a marker for functional heterogeneity of CD4+ T cells

We prepared a novel rat mAb specific for CD45 molecules bearing the epitope coded for by the alternative exon 6 of the murine CD45 gene (CD45RC). Together with available mAbs to alternative exon 4- and 5-dependent epitopes (CD45RA and CD45RB respectively), we found that the three alternative exons show differential expressions on murine lymphocytes. Flow cytometry analysis revealed that although B cells were homogeneously CD45RA+B+C+, the CD4+ T cells clearly included two populations, CD45RA-B+C- and CD45RA-B+C+. The CD8+ T cells were separated into CD45RA-B+C+ and CD45RA+B+C+ populations. Such features of epitope expression on the cell surface correlate well with message levels of corresponding alternative exons. In the CD4+ T cells, messages of alternative exons were associated with either one or two exon forms of the CD45 transcript. In CD8+ T cells, there were transcripts with one, two, or three alternative exons. When stimulated by an immobilized CD3 mAb, the CD45RC+CD4+ T cell subset preferentially secreted IL-2 and CD45RC-CD4+ T cells produced IL-4. Upon stimulation with concanavalin A, CD45RC-CD4+ T cells converted to CD45RC+ cells, and the level of CD45RC expression on the CD45RC+CD4+ T cell subset was up-regulated. These changes were unidirectional and irreversible. Therefore, differential expression of CD45RC probably delineates the functional heterogeneity of murine CD4+ T cells that is associated with the stages of CD4+ T cell maturation or activation.

[Clinicopathological survey of persistent hypocomplementemic glomerulonephritis in children; correlation of DPGN and MPGN type I]

We studied clinicopathologically 19 patients with abnormal urinary findings accompanying with persistent hypocomplementemia under age 15. They consisted of 6 patients with membranoproliferative glomerulonephritis (MPGN) type I, 2 with MPGN type II, 2 with focal MPGN, 8 with diffuse proliferative glomerulonephritis (DPGN), 1 with focal glomerulonephritis (FGN). 17 cases were treated with steroid. In 2 patients with MPGN type I and 1 patient with DPGN, the treatment resulted in normalization of serum C3 level and urinary abnormalities and improvement of histological findings. In 3 patients with DPGN, urinary abnormalities and hypocomplementemia have been persisted and histological findings changed to those of MPGN type I. Thus, DPGN with hypocomplementemia seems to be an early stage of MPGN type I.

Spermatogenesis in the Watase's shrew, Crocidura watasei--a light electron microscopic study

Spermatogenesis in the Watase's shrew, Crocidura watasei, was investigated by light and transmission electron microscopy. The cycle of the seminiferous epithelium was divided into 12 stages using the development of spermatids as a main criterion. The steps of spermatids were characterized by morphological changes of the nucleus and acrosomal structure. The relative frequencies of the stages 1 to x 11 were 11.0, 10.3, 6.8, 10.6, 24.0, 6.4, 4.4, 7.9, 6.4, 4.9, 3.7 and 3.6%, respectively. Four types of spermatogonia (A1, A2, In and B) could be discerned by the observation of whole mount samples. The development of spermatids was divided into four phases (Golgi, cap, acrosome and maturation phases), as in other mammals. In Golgi phase of the spermatid, several acrosomal granules were encountered. In cap phase, the acrosome gradually spread over the nuclear surface. In early acrosome phase, the acrosome began to elongate and reached the maximal length in step 8 spermatids. The acrosome of step 8 spermatids was twice as long as that of spermatozoa. In late acrosome phase, the acrosome was on the way of shrinkage. Finally, the fan-shaped acrosome was formed in maturation phase. These findings suggested that the process of acrosomal formation was quite characteristic in the Watase's shrew in that the spermatid acrosome elongated most prominently in the mammals hitherto examined.

[A case of anti-GBM nephritis (crescentic glomerulonephritis) associated with membranous nephropathy]

We report a case of endstage renal disease due to simultaneous occurrence of membranous nephropathy and crescentic glomerulonephritis associated with anti-GBM antibodies. The patient was a 60-year-old male and was hospitalized for prolonged anorexia and general malaise. On admission, his body temperature was 38.5 degrees C. Urinalysis revealed 3+ proteinuria and the sediment contained abundant erythrocytes. The urea nitrogen was 142.4 mg/dl, the creatinine 19.5 mg/dl, the potassium 6.47 mEq/dl and CRP 10.1 mg/dl. Anti-GBM antibodies were 1000EU/ml. Immediately after initiating hemodialysis, pulse steroid therapy, plasma exchange and continuous heparinization were performed. However, renal function had been impaired and maintenance hemodialysis was required. Histological examination of the renal specimen revealed marked epithelial crescent formation, whereas thickening of basement membrane and mesangial proliferation were not observed. By immunofluorescent staining, both bright linear and fine granular fixation of IgG and fine granular fixations of C3 along the glomerular capillary walls were observed. Electron microscopy showed subepithelial electron lucent deposits and thickening of the glomerular basement membrane, diagnostic of the advanced membranous nephropathy (stage IV).

Image manipulation: digital versus analog

A conceptual difference between "analog" and "digital" digitizing is reviewed. Analog and digital type image filing systems are discussed from a comparative point of view: The analog type is advantageous in the number of recordable images, the recording and reproducing speed, and the ability to record a moving picture, while the digital type, in which images are digitized when recorded, is capable of reproducing a higher quality image that does not deteriorate when copied repeatedly. It has the advantage that it easily interfaces with computer systems. As technology developed to compensate for the drawbacks of the digital type systems, image data compression was introduced. Finally, the possibility for recording a moving picture in a digital type system is discussed.

Specific inhibition of NGF receptor tyrosine kinase activity by K-252a

An involvement of protein tyrosine kinase in the transduction of the signals initiated by nerve growth factor (NGF) was investigated. A tyrosine kinase inhibitor, herbimycin, inhibited neurite outgrowth of rat pheochromocytoma PC12 cells induced by NGF but not that by dibutyryl-cAMP. Herbimycin and genistein blocked NGF-dependent activation of ras p21 whose essential function in neuronal differentiation has been reported. These observations suggested that tyrosine kinase activity is involved in the signaling pathways. K-252a, by contrast, inhibited NGF-induced but not EGF-dependent activation of ras p21. Tyrosine kinase activity of gp140trk, a constituent of NGF receptor, is activated by NGF for much a longer period compared to the activation of EGF receptor autokinase activity by EGF. We further demonstrated that autophosphorylation of gp140trk is selectively inhibited by K-252a.

Fabry's disease

A 20-year-old man presented with generalized acquired anhidrosis and heat intolerance which was confirmed by a sweat test. Other clinical features included severe pain of the extremities and cutaneous angiokeratomas. On electronmicroscopy, granules specific for Fabry's disease were observed in the endothelial cells. Biochemical examination revealed a decreased level of serum alpha-galactosidase A. These findings confirmed the diagnosis of Fabry's disease.

[A case of myocardial infarction in a young man with systemic lupus erythematosus]

Apparently the incidence of coronary artery disease in systemic lupus erythematosus (SLE) has been increasing. However, most of the cases had been treated with corticosteroids, and had atherosclerotic lesions in the coronary arterial tree. A 21-year-old man with latent and untreated SLE had an attack of acute myocardial infarction. Coronary arteriography showed eccentric stenotic lesion at the proximal segment of the right coronary artery. One week later, in the 2nd coronary arteriography, this stenotic lesion was not able to be recognized. We supposed that the coronary artery occlusion was due to thrombus formation, and was not related to atherosclerosis, arteritis and embolus. He had no coronary risk factors. Laboratory data showed lymphocytopenia, proteinuria, positive antinuclear antibody, and positive LE cell, and the case was diagnosed as SLE. Subsequent investigations showed the presence of antibodies to cardiolipin. It was suggested that anticardiolipin antibody and other thrombogenic factors were the causes of the coronary occlusive thrombosis in this patient with SLE.

Differential expression of a CD45R epitope(6B2) on murine CD5+ B cells: Possible difference in the post-translational modification of CD45 molecules

Although murine peritoneal B cells were homogenously positive for an epitope Lp-2, coded for by the alternative exon 4 of the CD45 gene, they were heterogenous with respect to the expression of another CD45R epitope, 6B2, of unknown exon dependency. While the majority of 6B2-high peritoneal B cells was composed of CD5- B cells, those with low or negative 6B2 were CD5+ B cells. Both 6B2+ and 6B2- peritoneal B cells expressed mainly the same largest CD45R transcripts, with all three alternative exon (4, 5, and 6) sequences. Further, a CD5+ B lymphoma cell line, BCL-1, which was found to be Lp-2+6B2- also had the largest isoform of CD45R molecules with all three alternate structures. Although enzyme digestion studies suggested that the 6B2 epitope resides in protein, not in sugar structures, it is likely that a post-translational modification of CD45R molecules is responsible for the presence or absence of 6B2 epitope expression on peritoneal CD5+ B cells. This event may be related to the differential role of CD45R molecules in regulating lymphocyte function.

Familial progressive renal tubulopathy

We report herein data on 6 male patients with progressive tubulopathy. These patients belonged to two families: the propositus, his father, a paternal first cousin, two paternal uncles, and a maternal uncle. A 7-year-old proband had mild proteinuria (1 g/day), consisting of beta 2-microglobulin, alpha 1-microglobulin and lysozyme, and aminoaciduria. Glycosuria and acidosis were absent. A 38-year-old father had mild proteinuria (2 g/day), including low-molecular-weight protein. Hypokalemia, hypophosphatemia, glucosuria, phosphaturia, aminoaciduria, and reduced urinary concentrating ability were also present. The other 4 affected family members also had low-molecular-weight proteinuria, detected by screening for beta 2-microglobulin. In addition, there were several abnormalities; aminoaciduria in all 6, phosphaturia in 4 of 6, hypercalciuria in all 6 and glycosuria in 2 of 6 patients. Tubular dysfunction was more severe in the older subjects, hence, the disease seems to progress with age. Familial low-molecular-weight proteinuria is apparently a progressive disease linked to a X-linked or to an autosomal dominant inheritance.

Evaluation of cervical cord function using spinal evoked potentials from surface electrode

Spinal evoked potentials from cervical skin surface (surface spinal evoked potentials) were measured to evaluate spinal cord function as a convenient method that precludes inserting electrodes into the epidural space, and results were compared with those of the former epidural recording method. Surface spinal evoked potentials were obtained from cervical skin surface over the C3, C5, and C7 spinous processes after median nerve stimulation in 18 normal subjects and 37 patients with a cervical lesion. In normal subjects, surface spinal evoked potentials consisted of three negative waves (N1, N2, N3). Abnormal N2 (80%) and abnormal N3 (100%) were observed in cervical myelopathy, and abnormal N2 was observed only in radiculopathy; this allows for differentiation between myelopathy and radiculopathy. Comparing preoperative and postoperative surface spinal evoked potentials, it was seen that improvement of clinical symptoms was proportional to that of surface spinal evoked potentials.

Cortical synaptogenesis in congenitally hydrocephalic HTX-rats using monoclonal anti-synaptic vesicle protein antibody

We attempted to develop a method for investigating impairment of synaptogenesis quantitatively involving measurement of the fluorescence intensity emitted by immunohistochemically stained rat brain using a monoclonal antibody (Mab 171B5) against a synaptic vesicle protein (SVP-38). We applied this method to congenitally hydrocephalic and non-hydrocephalic brains of HTX-rats, and compared the postnatal changes in the fluorescence intensity in the molecular layer of the cerebral cortex. In non-hydrocephalic HTX-rats, the fluorescence intensity remained nearly unchanged from the 1st to 7th postnatal day and then increased at an almost linear rate until the 21st postnatal day, when it reached 4.5 times the value on the 7th postnatal day. The increase thereafter was gradual until the 28th postnatal day. In hydrocephalic HTX-rats, the fluorescence intensity increased nearly in parallel with that in non-hydrocephalic HTX-rats up to the 21st postnatal day. On the 28th postnatal day, the fluorescence intensity showed a marked reduction (P less than 0.01). This finding indicates that despite the presence of continuous pressure due to progressive ventricular dilatation after birth, synaptogenesis in the cerebral cortex may be relatively resilient.

Identification of neurofibromatosis type I gene product as an insoluble GTPase-activating protein toward ras p21

The neurofibromatosis type I (NF1) gene was cloned as a gene whose structural change is closely related to the onset of a neurocutaneous disorder, neurofibromatosis type I. The predicted amino acid sequence of the NF1 gene product shows significant similarity to the catalytic domain of GTPase-activating protein (GAP) for ras p21. This GAP-related domain has been shown to have GAP activity when expressed by recombinant DNA technique, however little is known about the NF1 gene product expressed in tissues. Antibodies against the carboxy terminus and the GAP-related domain of the NF1 gene product were made to identify and characterize NF1 protein expressed in vivo. Both antibodies specifically reacted with a polypeptide with apparent molecular weight of 235 kDa in immunoblot and immunoprecipitation analyses. This 235 kDa protein is detected in brain but not in spleen, thymus, kidney, liver, lung and heart. The subcellular distribution of NF1 and GAP was studied using rat brain extract and was identified by the activity which was inhibited by antibodies against GAP-related domain of NF1 and anti-GAP respectively. The results show that NF1 protein mainly resides in the particulate fraction, in contrast to GAP, which is a soluble protein. We also found that a GAP activity which is not inhibited by anti-NF1 and anti-GAP exists in both the soluble and particulate fractions. The result suggests that there may be another GAP molecule.

The structure of glutaraldehyde in aqueous solution determined by ultraviolet absorption and light scattering

The structure of glutaraldehyde (GA) in aqueous solutions has been the subject of much debate. Since there were fundamental problems in the experiments in the preceding studies, in this article, the structure of GA was investigated with uv absorption and light scattering to avoid those problems. It was discovered that 70% glutaraldehyde solution contains a large quantity of polymeric species with cyclic hemiacetal structure. On dilution, the polymerized glutaraldehyde slowly converted to monomers. In dilute solution, glutaraldehyde is almost monomeric at pH 3-8, the major portion taking the cyclic hemiacetal structure. The structure of GA in 20% solution is similar to that in more dilute solution. alpha, beta-Unsaturated structure does not exist in aqueous solution regardless of the concentration of glutaraldehyde.

Cardiac musculature of the intrapulmonary vein in the musk shrew

The cardiac musculature of intrapulmonary veins was examined to elucidate its distribution pattern in the musk shrew, the primitive mammalian type, using by both light and electron microscopies. The musculature was distributed extensively from the hilum to the small veins less than 50 microns in diameter, suggesting that the phylogenic origin of this musculature may be traceable to the primitive mammalian types. Ultrastructure of cardiac myocyte in the intrapulmonary venous walls was essentially similar to that of left atrial myocyte. This suggests that the cardiac musculature may contribute to the regulation of pulmonary blood circulation. The abundance of large lipid droplets in both atrial and pulmonary myocytes was also observed and seemed to be the characteristic ultrastructure related to the physiological condition in this animal.

Proliferation of collagen fibrils and Ito cells in the liver after Japanese sake administration in undernourished rats as demonstrated by scanning electron microscopy

Intralobular fibrosis of the liver was induced in undernourished rats by administering Japanese sake for 12 days. Control rats administered the equivalent calories with glucose solutions did not show any fibrosis. In the sake group, Ito cells were increased and often clustered under the scanning electron microscope (SEM). Many collagen fibrils 0.1 microns in diameter twisted around Ito cells which had numerous microvillous projections. On the contrary, fibrils were not increased and Ito cells had rather smooth surfaces in the control group. The number of Ito cells counted under the SEM at 500 magnifications was increased in the sake group (mean +/- standard deviation; 70 +/- 23/mm2) as compared to the control group (44 +/- 9; P less than 0.01). The fact that Ito cells had proliferated and were tangled with collagen fibrils in the sake group was demonstrated three-dimensionally by SEM.

Exogenous Thy-1.1 expression as a marker for thymocyte maturation in transgenic mice

We established a line of transgenic mice carrying the exogenous mouse Thy-1.1 gene (8.2 Kb Eco RI genomic DNA fragment). In these mice, Thy-1.1 was expressed on thymocytes but not on peripheral T cells, presumably due to the lack of cis-acting element(s) on the microinjected genomic DNA. Even in the thymus, however, while most of the CD3/TCR- thymocytes were positive for the transgenic Thy-1.1 gene expression, the CD4+ or CD8+ single positive (SP) thymocytes were composed of two groups, one Thy-1.1+ and one Thy-1.1-, suggesting that the former belongs to cells at premature stages of terminal T cell differentiation. There was no difference in the amount of CD3/TCR complexes expressed on two such SP thymocyte subsets. In the double negative (DN) thymocytes, all the CD3/TCR+ cells were Thy-1.1-. These results suggest that the maturational process of CD3+ DN thymocytes differs from that of SP thymocytes. The unique distribution of Thy-1.1+ population among CD3+ thymocytes suggests that the transgenic Thy-1.1 gene expression can serve as a useful marker to examine terminal maturation processes of CD3+ thymocytes.

Nerve growth factor induces rapid accumulation of the GTP-bound form of p21ras in rat pheochromocytoma PC12 cells

The ras gene product (p21) is thought to transduce signals from various growth and differentiation factors. p21 is a GTP-binding protein, and its activity is regulated by the bound GDP/GTP ratio. We analysed p21-bound nucleotides in cell lysates of rat pheochromocytoma cell line PC12 cells stimulated with various factors. Nerve growth factors (NGF) rapidly increased the relative amount of active p21-GTP complex to as much as 20% of the total amount of p21 within 2 min. The amount of p21-GTP then declined to 8% after 10 min, and this level was sustained for at least 2 h. Epidermal growth factor (EGF) also stimulated a rapid accumulation of p21-GTP to the same extent as seen with NGF, but the amount of p21-GTP declined to 5% after 10 min and gradually returned to the basal level within 60 min. In contrast, basic fibroblast growth factor, interleukin 6 and dibutyryl cAMP, which induce neuronal differentiation of PC12 cells, did not stimulate the accumulation of p21-GTP at any time point examined. Phorbol 12-myristate 13-acetate also had no effect. Interestingly, the protein kinase inhibitor K-252a specifically suppressed the NGF-induced accumulation of p21-GTP, but did not suppress the EGF-induced response. These results strongly suggest that an active p21-GTP complex transduces the differentiation signal from NGF. It may also be suggested that the process of activating p21 is mediated by a K-252a-sensitive protein kinase(s).

Functional expression of the alpha 1 subunit of the AMPA-selective glutamate receptor channel, using a baculovirus system

Using a baculovirus expression vector system, the alpha 1 subunit of the mouse AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate)-selective glutamate receptor channel was expressed in insect Spdoptera frugiperda cells. Binding studies using [3H]AMPA showed that insect cells infected with the recombinant virus expressed approximately 1.8 x 10(5) binding sites per cell on their surface. The ligand binding characteristics of the receptors expressed in insect cells were examined. The baculovirus-insect cell expression system affords high-efficiency expression of the receptor in sufficient amounts to permit structural and functional analyses.