Endothelin receptor subtype B mediates autoinduction of endothelin-1 in rat mesangial cells

Autoinduction of endothelin-1 (ET-1) has been suggested to be involved in the profound and long-lasting effects of ET-1. We examined mechanisms that underlie autoinduction of ET-1 in cultured rat glomerular mesangial cells. Incubation of mesangial cells with ET-1 resulted in an immediate and dose-dependent stimulation of preproET-1 mRNA expression as assessed by polymerase chain reaction coupled with reverse transcription. Within 1 h of exposure to ET-1 (10(-7) M), preproET-1 mRNA expression was increased to a maximal level of 465 +/- 43% of the control value (p < 0.01), which was accompanied by significant stimulation of production of the immunoreactive ET-1 peptide. Nuclear run-off analysis revealed increases in the transcriptional rate of preproET-1 mRNA to 239 and 175% above the control values at 1 and 3 h of ET-1 stimulation, respectively. ET-1 also increased the stability of preproET-1 mRNA, resulting in an mRNA half-life of 60 min from 20 min seen in non-stimulated cells. Addition of an ETB-specific antagonist, RES701-1, at > 10(-9) M abolished ET-1 stimulation of preproET-1 mRNA (p < 0.001), whereas an ETA-specific antagonist, BQ123, was without effects (up to 10(-5) M). The ETB agonist, sarafotoxin S6c (10(-7) M), significantly stimulated preproET-1 mRNA expression to 201 +/- 14% above controls (p < 0.01), and effect that was lessened significantly by RES701-1 (p < 0.05). RES701-1 abolished the ET-1-induced production of the ET-1 peptide (p < 0.001). Taken together, we demonstrates that in mesangial cells, autoinduction of ET-1 occurs through the ETB receptor subtype via increases in both preproET-1 transcription and mRNA stability.

Identification of the human ERK gene as a putative receptor tyrosine kinase and its chromosomal localization to 1p36.1: a comparative mapping of human, mouse, and rat chromosomes

From a newly determined cDNA sequence of the human ERK gene, a highly hydrophobic portion was identified upstream of the putative tyrosine kinase domain. This is the first evidence that the ERK protein possesses a receptor-like membrane-spanning structure. Fluorescence in situ hybridization analysis of R-banded metaphase chromosomes revealed that the ERK gene is located in chromosome region 1p36.1. This locus is near the frequent translocation breakpoint or deletion region of neuroblastoma and some other cancers. A comparative mapping study of the mouse and rat homologues indicated that each counterpart maps to the mouse chromosome 4D2.2-D3 and rat chromosome 5q36.13 regions, both of which have conserved linkage homology to human chromosome 1p.

Mouse and human chromosomal assignments of mortalin, a novel member of the murine hsp70 family of proteins

Mortalin has been shown to exhibit differential distributions in cells with mortal and immortal phenotypes. In the present study, we report mot-2 cDNA cloning from RS-4 cells--an immortal clone from CD1-ICR mouse embryonic fibroblasts--and the chromosomal assignments of mortalin related genes to mouse chromosomes 18 and X by fluorescence in situ hybridization. Similar analysis assigned the gene to chromosome 5q31.1 in human.

Myosin-actin interaction plays an important role in human immunodeficiency virus type 1 release from host cells

We examined the potential role of myosin and actin in the release of human immunodeficiency virus type 1 (HIV-1) from infected cells. Wortmannin (100 nM to 5 microM), an effective inhibitor of myosin light chain kinase, blocked the release of HIV-1 from infected T-lymphoblastoid and monocytoid cells in a concentration-dependent manner. Cytochalasin D, a reagent that disrupts the equilibrium between monomeric and polymeric actin, also partially inhibited the release of HIV-1 from the infected cells. At the budding stage, myosin and HIV-1 protein were detected in the same areas on the plasma membrane by using dual-label immunofluorescence microscopy and immunoelectron microscopy. In the presence of 5 microM wortmannin, viral components were observed on the plasma membrane by using immunofluorescence microscopy and electron microscopy, implying that wortmannin did not disturb the transport of viral proteins to the plasma membrane but rather inhibited budding.

Abnormal integrity of the nucleolus associated with cell cycle arrest owing to the temperature-sensitive ubiquitin-activating enzyme E1

A mouse cell mutant, ts85, containing the temperature-sensitive ubiquitin-activating enzyme was arrested in G2 phase at the non-permissive temperature. In the arrested cells, azure C, a nucleolus-specific stain, revealed a U-shaped or ring-shaped arrangement of nucleolar lobes with an unstained region in the center. Silver staining of the nucleolar organizer region (NOR) and fluorescence in situ hybridization (FISH) with rDNA both gave signals in azure C-positive regions. Electron microscopic examination revealed a cloud of unidentified electron-dense particles (diameter approximately 70 nm) in the azure C-negative center space. When the arrested cells were released into M-phase, we observed the association of NOR-bearing chromosomes with a pulverization-like abnormality. FISH with rDNA and NOR silver staining demonstrated that the pulverization-like abnormality was restricted to NORs. The frequent occurrence of persistent nucleolar material in prophase and prometaphase of the stressed cells after release indicated a delayed dissociation of the nucleolus that brought about the abnormal chromosomes in M-phase. ts85 cells transfected with the mouse E1 cDNA recovered growth at the non-permissive temperature and no longer showed abnormal nucleolar morphology. It seems that the ubiquitin system plays a role in the dissolution of the nucleolus, possibly involving the NOR-bearing chromosomes.

A functional role for endogenous atrial natriuretic peptide in a canine model of early left ventricular dysfunction

Asymptomatic or early left ventricular dysfunction in humans is characterized by increases in circulating atrial natriuretic peptide (ANP) without activation of the renin-angiotensin-aldosterone system (RAAS). We previously reported a canine model of early left ventricular dysfunction (ELVD) produced by rapid ventricular pacing and characterized by an identical neurohumoral profile and maintenance of the natriuretic response to volume expansion (VE). To test the hypothesis that elevated endogenous ANP suppresses the RAAS and maintains sodium excretion in ELVD, we assessed the effects of antagonism of ANP on cardiorenal and neurohumoral function in ELVD. Chronic ANP suppression was produced by bilateral atrial appendectomies before the production of ELVD by rapid ventricular pacing (ELVD-APPX, n = 5). This group was compared with a separate group with ELVD and intact atrial appendages (ELVD-INTACT, n = 8). ELVD-APPX was characterized by lower circulating ANP (50 +/- 11 vs. 158 +/- 37 pg/ml, P < 0.05), activation of plasma renin activity (PRA) (9.4 +/- 2.4 vs. 0.6 +/- 0.4 ng/ml per h, P < 0.05) and aldosterone (36.4 +/- 12.5 vs. 2.5 +/- 0.0 ng/dl, P < 0.05) when compared to ELVD-INTACT. In comparison to the ELVD-INTACT group, sodium excretion was decreased before and during VE in the ELVD-APPX group. Acute ANP antagonism was produced by administration of the particulate guanylate cyclase coupled natriuretic peptide receptor antagonist, HS-142-1, to seven conscious dogs with ELVD and intact atrial appendages (ELVD-INTACT). HS-142-1 decreased plasma concentrations and renal generation of the ANP second messenger, cGMP, and was associated with activation of PRA and sodium retention with enhanced tubular sodium reabsorption. These data support a significant role for elevated endogenous ANP in the maintenance of sodium excretion and regulation of the RAAS in experimental ELVD.

Effects of ANP receptor antagonists on ANP secretion from adult rat cultured atrial myocytes

Atrial natriuretic peptide (ANP) is a hormone-secreted predominantly by atrial myocytes. ANP exerts many of its actions via activation of the particulate guanylyl cyclase receptor ANPR-A and the formation of guanosine 3',5'-cyclic monophosphate (cGMP), which serves as a second messenger in the target cells. Using membrane-permeable cGMP analogues (8-bromo-cGMP and dibutyryl- cGMP), we first tested the hypothesis that ANP secretion by adult rat cultured atrial myocytes can be modulated through the second messenger cGMP. Second, we examined the effects of two competitive ANPR-A receptor antagonists, namely HS-142-1 and anantin, on cGMP formation and ANP secretion from cultured atrial myocytes. Cultured atrial myocytes secreted large quantities of immunoreactive (ir) ANP under basal conditions. We found that cGMP analogues inhibited basal irANP secretion from cultured atrial myocytes, whereas HS-142-1 and anantin had stimulating effects. HS-142-1 and anantin reduced cGMP formation in cultured atrial myocytes at basal conditions. These results suggest an autoregulatory mechanism of ANP secretion by atrial myocytes in an autocrine/paracrine fashion.

Subtypes of endothelin ETA and ETB receptors mediating tracheal smooth muscle contraction

In the isolated rabbit trachea, endothelin (ET)-1, ET-3 and the selective ETB receptor agonists, IRL 1620 and sarafotoxin S6c (STXc), induced contraction with EC50 of 2-9 nM. An ETA1 receptor antagonist, BQ-123, was ineffective whereas desensitization of the ETB receptor strongly antagonized the effect of ET-3, IRL 1620 and STXc. An ETB1 receptor antagonist, RES-701-1, antagonized the effects of ET-3 and IRL 1620 whereas the effect of STXc was antagonized by an ETB2 receptor antagonist, BQ-788. In the ETB-desensitized trachea, only ET-1 induced large contraction that was partially antagonized by BQ-123. These results suggest that ET induces tracheal contraction by activating multiple ET receptors: the ET-1-selective ETA (BQ-123-sensitive ETA1 and insensitive ETA2 subtypes) and the isopeptide-nonselective ETB receptors (RES-701-1-sensitive ETB1 and insensitive ETB2 subtypes).

Localization of the genes for the 100-kDa complement-activating components of Ra-reactive factor (CRARF and Crarf) to human 3q27-q28 and mouse 16B2-B3

Human and mouse genes for the complement-activating component (P100) of Ra-reactive factor, a novel bactericidal factor (CRARF and Crarf), were mapped to R-banded metaphase chromosomes by fluorescence in situ hybridization with human and mouse P100 cDNA 2.7 and 2.0 kb long, respectively. The localization of fluorescent signals showed that CRARF and Crarf mapped to human 3q27-q28 and mouse 16B2-B3, respectively. This evidence is consistent with the previous assumption that the distal portion of the long arm of human chromosome 3 is homologous to the proximal portion of mouse chromosome 16.

A genomic clone containing a telomere array maps near the centromere of mouse chromosome 6

A lambda clone of mouse DNA containing a short array of telomere hexamers has been localized by FISH to a region close to the centromere of Chromosome (Chr) 6. Amplification of DNA with primers flanking an SSR showed that most inbred strains carry one of two alleles, although five other alleles were found among the inbred strains and 11 other alleles were found in wild-derived mice. Analysis of the DNA from four Robertsonian translocations suggests that the amplified sequence is still present in these chromosomes. The finding of two fragments associated with the Sig mutant suggests that the clone lies within a congenic region created when the mutant, obtained in a (C3H x 101)F1, was backcrossed to C57BL/6J. This region might include all or part of the centromere. Comparison of the segregation of the amplification product with the segregation of centromeric heterochromatin in an interspecies backcross, (C57BL/6 x M. spretus)F1 x M. spretus, (BSS) shows 1/72 recombinants with the centromeric heterochromatin, while 1/62 recombinants occurred in a BSB backcross. Analysis of other loci at the proximal end of Chr 6 gives the combined map Hc6-0.73-D6Mit86-0.73-D6Rp2-2.2-D6Mitl-2.2-Wn t2-3.0-Cpa. Data from a third cross show that Cola2 lies between D6Mit82 and D6Rp2. The portion of the telomere array, Tel-rs3, that has been sequenced contains only 13/31 repeats of the consensus sequence. A variety of sequence changes from the consensus hexamer suggests that this array has been removed for a long time from evolutionary pressures to retain the TTAGGG sequence.

Application of fluorescence in situ hybridization in genome analysis of the mouse

Fluorescence in situ hybridization (FISH) is an effective technique for localizing cloned DNA probes directly onto metaphase chromosomes. Human genome mapping using FISH has been significantly enhanced by the development of new techniques, especially high-resolution gene mapping with direct R-banding FISH and physical gene ordering with multi-color FISH. By contrast, FISH techniques have not been put to practical use for the analysis of the mouse genome compared with the human. We have developed and modified FISH techniques for use in mouse genome analysis. In this article we summarize and review our recent results with FISH analyses in the following studies: (i) high-resolution gene mapping with the direct R-banding FISH, (ii) analysis of chromosomal rearrangement with multi-color FISH, (iii) establishment of centromere mapping with the major satellite DNA probe, (iv) analysis of chromatin structure in meiotic cells, and (v) application of FISH in cytogenetic studies of genetic variation in the mouse, showing that these applications of FISH are very useful for mouse genome analysis.

An effective LDL removal filter for the treatment of hyperlipidemia

On-line membrane plasma fractionation techniques have made semiselective removal of pathological macromolecules practical. However, several problems such as cryogel formation exist when the procedure is performed at ambient temperature. Cryogel formation takes place when heparinized plasma is cooled below 35 degrees C and when it tends to occlude the pore structure of the secondary filter membrane resulting in a poor molecular cut off of the macromolecular filter. Thermofiltration is one of the on-line plasma fractionation techniques used when warming plasma from 37 to 42 degrees C to prevent cryogel formation. Thermofiltration enhanced the performance of the lipofilter (Kuraray 4A) and demonstrated better molecular cut off between low density lipoprotein (LDL) cholesterol and high density lipoprotein (HDL) cholesterol than double filtration plasmapheresis (DFPP). An improved lipofilter (Kuraray 5A) has been developed and has shown better molecular cut off between LDL cholesterol and HDL cholesterol than the 4A filter. However, cryogel formation still occurred even using the 5A filter during the DFPP procedure. Thermofiltration maintains the performance of the secondary filter by preventing cryogel formation. Further studies are required to evaluate the enhanced performance of the 5A filter by thermofiltration.

A thermoconductive and thermoselective leukocyte filter

Previously, it was reported by our group that the superphysiological temperature of over 43 degrees C affected leukocyte properties. It was speculated that heat treatment might alter the immunological properties of leukocytes. In order to take advantages of this phenomenon, attempts were made to develop a thermoconductive and thermoselective leukocyte filter. A stainless steel fiber was selected for the new material of a leukocyte filter due to its good heat conductance, stability during thermal change, and inertness to any chemicals. Preliminary studies were conducted to evaluate the effect of fiber diameter and temperature on the filtration of blood cells. As a result, more than 99% of white blood cells (WBCs) and platelets were removed utilizing a 4 microns diameter fiber filter. The environmental temperatures of the filtration process were varied to 4, 20, 36, and 50 degrees C for 5 min. Almost 95% of WBCs and platelets were removed at 4, 20, and 36 degrees C. However, the reduction of platelets was remarkably suppressed at 50 degrees C (54%). Additionally, the removal of lymphocytes was significantly lower than that of neutrophils at 50 degrees C (69% vs. 83%; p = 0.0002). These data demonstrate that effective heat treatment and removal of leukocytes are possible with an ultrafine stainless steel fiber filter.

Magnetic resonance imaging of the central nervous system in the kitten

The optimum technical conditions for magnetic resonance imaging (MRI) of the central nervous system (CNS) in the 3-week-old kitten were investigated with a low (0.2 T) magnetic field MRI unit equipped with a custom-made solenoid radio frequency (RF) coil. In the brain, T1 weighted images (TR/TE = 500/38 msec) and T2 weighted images (TR/TE = 1,800/110 msec) clearly delineated each anatomical portion of the brain. In the spinal cord, T2 weighted images (TR/TE = 1,500/110 msec) demonstrated structures distinctly. These results suggest that even low magnetic field MRI can be used for noninvasive scanning of small animals including new born animals.

Chromosome mapping of human (ZNF147) and mouse genes for estrogen-responsive finger protein (efp), a member of the RING finger family

We have previously identified an estrogen-responsive gene, efp (estrogen-responsive finger protein), that encodes a putative zinc finger protein (Proc. Natl. Acad. Sci. USA 90: 11117-11121, 1993). The efp protein has a RING finger, a variant type of zinc finger motif, B1 box, and B2 box, each having a pair of zinc fingers, present in a family of apparent DNA-binding proteins. Some members of this family have transformation capabilities when found in chromosomal translocations. Chromosome mapping of the efp gene by fluorescence in situ hybridization reveals that human EFP (ZNF147) is located at 17q23.1 and that mouse Efp is located at 11C. These results provide additional evidence that the mouse 11C region displays conserved synteny with the 17q23.1 region of the human genome.

Multi-enzyme reference material from established human cell lines and human sources

A multi-enzyme reference material was prepared from seven enzymes of asparatate aminotransferase (AST, EC 2.6.1.1), alanine aminotransferase (ALT, EC 2.6.1.2), alkaline phosphatase (ALP, EC 3.1.3.1), lactate dehydrogenase (LD, EC 1.1.1.27), creatine kinase (CK, EC 2.7.2.2), gamma-glutamyltranspeptidase (gamma-GT, EC 2.3.2.2) and amylase (AMY, EC 3.2.1.1) which were purified from human sources including established human cell lines. The enzymatic properties of the material closely resembled those of human serum. In lyophilized form the preparation was stable for at least 200 days when stored at 40 degrees C. Intermethod comparisons of the enzyme activities in 80 clinical specimens were done by correcting the mean values with calibration constants for different assay methods resulting from use of a human serum, the multi-enzyme reference and a commercial control serum. The results from the comparison for the six enzymes of AST, ALT, LD, CK, gamma-GT and AMY in use of the multi-enzyme reference were almost the same as those with use of a human serum as a calibrator, but were not satisfactory for ALP. Even though further search for more reliable material for ALP is required the multi-enzyme reference material can be used for standardization in clinical chemistry.

High-performance liquid chromatographic assay for farnesyl-protein transferase activity with dabsylated peptide

An HPLC assay for farnesyl-protein transferase activity using a dabsylated peptide is described. The substrates used were a synthetic dabsylated nonapeptide, N-dabsyl-L-serinyl-L-methioninyl-L-glycinyl-L-++ +leucinyl-L-prolinyl-L-cysteinyl- L-valinyl-L-valinyl-L-methionine, corresponding to the C-terminal peptide sequence of human N-Ras p21 without the N-terminal serine, and farnesyl diphosphate. The product was separated from the substrates on a reversed-phase C18 column, using gradient elution with acetonitrile (0.05% trifluoroacetic acid)-water (0.1% trifluoroacetic acid) and was detected at 436 nm. The addition of the farnesyl group to the peptide was confirmed by MS and NMR. Enzymatic reaction was ascertained from the dependences on time, on the protein of the enzyme source and on the substrates. The reaction was specifically inhibited by L-cysteinyl-L-valinyl-L-valinyl-L-methionine, the tetrapeptide corresponding to the "CAAX" motif. The limit of detection was 2 pmol per 100-microliters reaction mixture. The farnesyl-protein transferase activity can quantitatively be measured up to 200 micrograms cytosolic protein in human liver. This method provides a convenient and quantitative assay for crude materials, such as tissue homogenate from clinical samples, without the use of radioactive probes and large amounts of Ras protein.

Distribution of the Kexin family proteases in pancreatic islets: PACE4C is specifically expressed in B cells of pancreatic islets

The distribution of Kexin family proteases in adult rat pancreatic islets was investigated by immunohistochemical means using a series of specific antibodies specific for PC1, PC2, PC6, Furin, PACE4A and a recently identified member of the Kexin family, PACE4C. PACE4C expression was limited to B cells of the pancreatic islets. PC2 was found in A and in some D cells more than in B cells and PC1 was evident only in B cells. Furin and PC6 were weakly and evenly expressed in the entire islet. PACE4A was hardly found in the islets. These findings indicated that individual Kexin family proteases are uniquely distributed in the islets and suggested that these proteases share roles in these cells as follows: PC2 is involved in the peptide hormone precursor processing in A cells and in D cells, and PACE4C, PC1 and PC2 (mainly PACE4C and PC1) are responsible for the processing event(s) specific to B cells.

Interferon-gamma (IFN-gamma) production by human T lymphocytes upon Legionella pneumophila stimulation in vitro

In vitro immune responses to Legionella pneumophila were investigated. When human peripheral blood lymphocytes (PBL) from healthy volunteers were stimulated with formalin-killed L. pneumophila for 7 days in vitro, strong proliferative responses were observed. The responding cells were shown to be a CD4 T cell subset. It was also found that the CD4 T cells secreted significant amounts of IFN-gamma into the PBL culture supernatant. The production of IFN-gamma and IL-4 by PBL was measured semiquantitatively by reverse transcriptase-assisted polymerase chain reaction (RT-PCR) methods. Formalin-killed or live L. pneumophila-stimulated PBL expressed the mRNA for IFN-gamma but not the mRNA for IL-4. The results suggest that the whole bacterium, as opposed to the supernatant, predominantly stimulates Th1 type helper T cells. The cloned T cells specific for L. pneumophila expressed the mRNA for IFN-gamma but not for IL-4. In contrast to formalin-killed or live L. pneumophila stimulation, when PBL were stimulated with the bacterial culture supernatant, the proliferating T cells produced the mRNA for IL-4 as well as for IFN-gamma. A significant correlation between the proliferative response to formalin-killed L. pneumophila and IFN-gamma release in culture was observed (r = 0.6932, P < 0.001) in PBL from 30 healthy volunteers. From these in vitro studies, it is suggested that the whole L. pneumophila bacterium and their soluble antigens stimulate T cells in a manner which results in a different pattern of cytokine production.

Relationship between granulocyte elastase levels and perinatal infections

This study was conducted in order to investigate the usefulness of granulocyte elastase levels as predictive factors in the onset of perinatal infections. The subjects were 41 patients who delivered within 48 h after amniocentesis after giving their informed consent. The relationship between cervical granulocyte elastase (Cx-E), serum C-reactive protein (CRP) and amniotic fluid granulocyte elastase (Af-E), and placental infections and neonatal infections was comparatively investigated. In some cases, gastric juice granulocyte elastase in neonates (Gj-E) was measured, and the correlation by site was investigated. Elastase levels were not used as a management protocol. In predicting neonatal infections, diagnostic efficacy (sensitivity x specificity) of placental infections (0.97) and abnormal Af-E (0.79) were superior to those of abnormal Cx-E (0.40) and abnormal CRP (0.49). There was no correlation between Cx-E and Af-E or between Cx-E and Gj-E; however, a very close correlation was noted between Af-E and Gj-E. In predicting abnormal amniotic fluids, Cx-E (> or = 1.2 micrograms/ml) + CRP (> or = 1.0 mg/dl) had the highest diagnostic efficacy with 0.58. These findings demonstrate that Af-E is a good index for predicting the onset of neonatal infections. In predicting abnormal amniotic fluid, it might be advisable to consider amniocentesis in order to diagnose intrauterine infections, when both Cx-E and CRP show abnormal levels.

Cerebral magnetic resonance angiographic findings in severe preeclampsia

OBJECTIVE

The purpose of our study was to investigate the cerebral pathophysiology of severe preeclampsia using the noninvasive method of magnetic resonance angiography.

STUDY DESIGN

We studied cerebral magnetic resonance angiography findings in 9 severely preeclamptic patients.

RESULTS

Magnetic resonance angiographies were abnormal on first scanning within 48 h postpartum, followed by normal findings on repeat scanning during the 1st postpartum month in 6 patients. The most common abnormality was vascular narrowing of anterior cerebral artery and basilar artery. Three of these 6 patients complained of headaches and/or visual disturbances.

CONCLUSION

This study shows that cerebral artery vasospasm is seen in some severe preeclamptic patients.