Gene expression of bone matrix proteins and endothelin receptors in endothelin-1-deficient mice revealed by in situ hybridization

Endothelin-1 (ET-1) was first found as a vasoconstrictor protein excreted by vascular endothelial cells, but recently ET-1 has been considered to have widespread functions that include regulation of osteochondrogenic metabolism. We analyzed sections of head regions in ET-1 knockout mice that are known to have abnormalities in pharyngeal arch-derived tissues and found that there was severe hypoplasia in facial bones. The hypoplasia suggests that the matrix mineralization system of facial bones is disrupted in ET-1-/- homozygous mice. To elucidate whether osteogenic cells in facial bones are the targets for ET-1 and whether expression of bone matrix genes are modulated by ET-1, we examined gene expression of ET-1 receptors, ETA and ETB, and that of the bone matrix proteins, osteonectin (ON) and osteopontin (OP), both in the head regions of ET-1+/- heterozygous and ET-1-/- homozygous mice by means of in situ hybridization. Different patterns of expression between ETA and ETB mRNAs were observed in both groups. In 18.5 days post coitus fetuses, ETA mRNA was most strongly expressed in osteogenic cells along craniofacial bones, but ETB mRNA was most strongly expressed in trunks of trigeminal nerve. This finding suggests that ET-1 may modulate osteogenic cells through ETA receptor but not through ETB receptor. The expression patterns of ETA, OP, and ON mRNAs were distinct between the two groups. In the lower jaw of ET-1+/- heterozygous mice, the ETA, ON, and OP mRNA positive cells were scattered in the inner and outer regions of the thick bone matrix, but in ET-1-/- homozygous mice, cells containing those mRNAs were located close to each other at the surface of thin bone matrix. However, cellular expression of ON and OP mRNAs in osteogenic cells of ET-1-/- homozygous mice was not suppressed as compared with ET-1+/- heterozygous mice. We conclude that ET-1 may regulate proliferation and migration of osteogenic cells in the maxillofacial region, rather than modulating the expression level of ON and OP mRNAs.

[HRCT findings of pulmonary Mycobacterium avium complex: a comparison with tuberculosis]

Computed tomographic (CT) findings of 70 patients with Mycobacterium avium complex (MAC) disease were analyzed by two chest radiologists and compared with those of 37 patients with Mycobacterium tuberculosis infection. Common CT findings in patients with MAC, included bronchiectasis (97%), small nodules (89%), parenchymal distortion (60%), bronchial wall thickening (56%), consolidation (50%) and cavity formation (49%) and small nodules (86%), bronchiectasis (70%), consolidation (57%) and bronchial wall thickening (51%) in patients with Mycobacterium tuberculosis. Bronchiectasis and parenchymal distortion were significant in patients with MAC compared with Mycobacterium tuberculosis patients. Bronchiectasis involving the RUL, RML, lingula and LLL and small nodules involving the RML were often seen in patients with MAC. Both bronchiectasis and small nodules were commonly observed in multiple lobes in both types of patients. Cavities in MAC infection tended to be thin and smooth walled, and less commonly associated with consolidation. We conclude that CT findings of MAC infection were characterized by widely distributed bronchiectasis and small nodules and/or cavities with thin, smooth walls. These CT findings are one of the keys in differentiating MAC from Mycobacterium tuberculosis.

Ovarian endometrioid adenocarcinoma associated with steroidogenic foamy stromal cells

A case of 69-year-old woman with endometrioid adenocarcinoma of the ovary with functioning stromal cells is presented. The patient complained of genital bleeding. Endometrial curettage revealed endometrial hyperplasia. Pre-operative levels of serum estradiol and progesterone were elevated, and serum gonadotropin levels were suppressed. The surgical specimen contained fist-sized, bilateral, solid, ovarian tumors and a mildly enlarged uterus. Histologically, the proliferating, atypical, columnar cancer cells resembled early secretory, endometrial epithelial cells with subnuclear vacuolation, and there were clusters of fat-laden foamy cells in the stroma. Immunohistochemically, the cancer cells were positive for cytokeratin and progesterone receptor but negative for estrogen receptor. The stromal foamy cells were immunoreactive for vimentin, progesterone receptor, P450 side chain-cleavage, 3 beta-hydroxysteroid dehydrogenase, and adrenal 4-binding protein. Immunoreactivities of P450c-17 alpha hydroxylase and aromatase were only focally observed. These findings indicated that the stromal cells were steroidogenic and mainly produced progesterone. The cancer cells that expressed progesterone receptors showed morphologic changes in response to hormonal stimulation.

The macrophage scavenger receptor type A is expressed by activated macrophages and protects the host against lethal endotoxic shock

During gram-negative bacterial infections, lipopolysaccharide (LPS) stimulates primed macrophages (Mphi) to release inflammatory mediators such as tumor necrosis factor (TNF)-alpha, which can cause hypotension, organ failure, and often death. Several different receptors on Mphi have been shown to bind LPS, including the type A scavenger receptor (SR-A). This receptor is able to bind a broad range of polyanionic ligands such as modified lipoproteins and lipoteichoic acid of gram-positive bacteria, which suggests that SR-A plays a role in host defense. In this study, we used mice lacking the SR-A (SRKO) to investigate the role of SR-A in acquired immunity using a viable bacillus Calmette Guérin (BCG) infection model. We show that activated Mphi express SR-A and that this molecule is functional in assays of adhesion and endocytic uptake. After BCG infection, SRKO mice are able to recruit Mphi to sites of granuloma formation where they become activated and restrict BCG replication. However, infected mice lacking the SR-A are more susceptible to endotoxic shock and produce more TNF-alpha and interleukin-6 in response to LPS. In addition, we show that an antibody which blocks TNF-alpha activity reduces LPS-induced mortality in these mice. Thus SR-A, expressed by activated Mphi, plays a protective role in host defense by scavenging LPS as well as by reducing the release by activated Mphi of proinflammatory cytokines. Modulation of SR-A may provide a novel therapeutic approach to control endotoxic shock.

Phenotypic rescue of the albino mutation in the medakafish (Oryzias latipes) by a mouse tyrosinase transgene

Mutations of the tyrosinase gene are one common cause of a similar phenotype in all vertebrates, known as albinism. In an attempt to contribute to an understanding of the genetic hierarchy governing the development of pigmentation, we have used a mouse tyrosinase minigene under the control of its 5.2 kb upstream promoter region to rescue two different albino mutations in the medakafish, Oryzias latipes. Around hatching stages an almost perfect phenocopy of the wildtype pigmentation was obtained. Subsequent ectopic melanin overproduction indicated a possible incompatibility of the heterologous mouse promoter for stable expression during the entire ontogenesis. Like in some tyrosinase transgenic mouse lines a strong variegation effect was observed. The transgene-mediated pigmentation phenotype was obtained up to the eighth offspring generation. The phenotypic effects of the tyrosinase transgene in different albino mutant strains places the i3-locus upstream and the b-locus downstream of the tyrosinase locus i1 in the genetic hierarchy leading to wildtype pigmentation.

Increase or decrease of HDL-cholesterol concentrations during pravastatin treatment depending on the pre-treatment HDL cholesterol levels

OBJECTIVE

The effect of pravastatin was evaluated using patient data accumulated in the data base of a hospital information system (HIS).

METHODS

We selected 130 patients treated with pravastatin 10 mg per day, for a minimum period of 4 weeks.

RESULTS

In the t test analysis, the reduction rates of total cholesterol (TC) and low-density lipoprotein (LDL) levels for pravastatin administration were 18%, and 27%, respectively. These values were similar to previous reports. The high-density lipoprotein (HDL) level, however, did not change significantly, although previous reports have shown an elevation of HDL levels. In an attempt to explain the origin of this difference, we studied the pretreatment value dependence of the cholesterol change using regression analysis. We found that pravastatin raised the HDL level in those cases where pretreatment values were lower than 58 mg.dl-1 and reduced it for higher values. We also showed that the reductions of TC, LDL and triglyceride (TG) levels correlated positively with their pretreatment values.

Dimerization and DNA binding facilitate alpha-helix formation of Max in solution

Max is a basic region/helix-loop-helix/leucine zipper (b/HLH/Z) protein that forms a hetero-complex with the Myc family proteins Myc, Mad, and Mxi1, and a homo-complex with itself. These complexes specifically bind to double-stranded DNA containing CACGTG sequences. Here, we report on the structural properties in aqueous solution of a 109-amino-acid protein, Max110, corresponding to the N-terminal domain of Max containing the b/HLH/Z motif (residues 2-110), as characterized by combined use of circular dichroism (CD) and sedimentation equilibrium experiments. The results showed that the alpha-helical content of Max110 increases with increasing protein concentration. The sedimentation equilibrium data indicated that Max110 exists as a monomer at low protein concentration, and forms a dimer at high protein concentration. Further increases in the alpha-helical content of Max110 occur upon addition of DNA with the CACGTG recognition sequence. Thus, dimerization and binding to DNA of Max both favor an increase of the alpha-helical content.

Hairpin structure of an RNA 28-mer, which contains a sequence of the enzyme component of a hammerhead ribozyme system: evidence for tandem G:A pairs that are not of side-by-side type

An RNA 28-mer (Rz28) was obtained as a major product by in vitro transcription with T7 RNA polymerase of a promoter-template DNA, which contains a sequence for the enzyme component, RNA 24-mer (Rz24), of a mutant hammerhead ribozyme system. Sequence analysis and enzymatic probing study showed that Rz28 has 4 extra nucleotides at the 3'-terminus, the sequence of which is complementary to that of the 5'-terminal sequence of Rz24, and forms a stable hairpin structure. NMR studies using a 15N-guanine-labeled derivative suggested that Rz28 contains tandem G:A pairs that are not of the side-by-side type which is found in the crystal structure of hammerhead ribozyme complexes. Comparison of the HMQC spectra of 15N-guanine-labeled Rz28 and Rz24 suggested that Rz24 also contains the same type of tandem G:A pairs.

[Acute eosinophilic pneumonia associated with aspirin]

A 21-year-old man was admitted to our hospital with acute progressive dyspnea and a high fever. He had started smoking 6 weeks before admission. A chest radiograph showed diffuse infiltrates with Kerley B lines and bilateral pleural effusions. There was no evidence of infection. His condition improved rapidly and without medication. On admission the concentrations of interleukin-5 in bronchoalveolar lavage fluid and in blood were high, but they were normal one week later. Acute eosinophilic pneumonia was diagnosed. A positive result of a lymphocyte stimulation test indicated that the development of symptoms was closely associated with ingestion of aspirin. We know of no previous report of acute eosinophilic pneumonia associated with aspirin.

Most anchoring fibrils in human skin originate and terminate in the lamina densa

Anchoring fibrils (AF) at the dermo-epidermal junction are well characterized as ultrastructural entities. They are composed mainly of collagen VII and play a key role in dermo-epidermal adhesion. Previous studies have suggested that AF originate in the lamina densa (LD), extend perpendicularly into the dermis, and insert into amorphous elements, called "anchoring plaques," in the dermal connective tissue. To elucidate the precise structural organization of the AF network in human skin, we analyzed quantitatively the distribution of different domains of collagen VII in the epidermal basement membrane zone, using various techniques of immunoelectron microscopy with a range of domain-specific antibodies that we prepared. Some electron-dense amorphous structures (ie, anchoring plaques) that were positive with aminoterminal end of collagen VII could be recognized only by pre-embedding en bloc labeling, and not by postembedding section labeling of immunoelectron microscopy. Quantitative analysis of surface labeling with postembedding immunoelectron microscopy demonstrated that most (> 90%) gold particles labeling the epitopes in the aminoterminal (NC-1 domain) of collagen VII were precisely localized to the LD, whereas no specific labeling was observed in the dermis. Most (> 90%) of the gold particles labeling the carboxyterminal end of collagen VII localized at a 160- to 360-nm distance from the LD, and most (> 90%) of the labeling epitopes in the central triple-helical collagenous domain were distributed between the LD and up to 360 nm from it; no specific labelings were observed beyond this area. These results suggest that most (> 90%), if not all, of the AF in human skin do not extend perpendicularly into the dermis, but instead originate and terminate in the LD, forming individual semicircular loops that constitute a network of AF.

[Gene Polymorphism of 5, 10-methylenetetrahydrofolate reductase as a coronary risk factor]

Hyperhomocysteinemia has been identified as a possible risk factor for coronary artery disease. The association of the alanine/valine (A/V) polymorphism of 5, 10-methylenetetrahydrofolate reductase (MTHFR), one of the key enzymes catalyzing re-methylation of homocysteine, with coronary artery disease was examined in 362 Japanese males with a diagnosis of coronary artery disease confirmed with coronary angiography. The A/V polymorphism was analyzed with PCR followed by Hinf I digestion. The screening of 778 male volunteer controls revealed that the frequency of V allele in Japanese was 0.33, comparable to that in the French Canadian population. The VV genotype, which correlates with increased plasma homocysteine levels due to reduced activity and increased thermolability of this enzyme, was significantly more frequent in patients with coronary artery disease (15.7%, n = 362) than in controls (10.2%, n = 778; p = 0.0067). The association of the VV genotype with coronary artery disease was further increased in patients with > or = 99% stenotic lesion (p = 0.0010). In these patients, the frequency of the VV genotype was significantly higher in patients with triple-vessel disease (26%) than in patients with single- or double-vessel disease (15% and 14%, respectively). The fasting plasma homocysteine levels in VV subjects were higher than those in AV or AA subjects. The VV genotype of MTHFR associated with increased plasma homocysteine levels may represent an important genetic risk factor for coronary artery disease, especially with the occurrence of myocardial infarction.

Properties of hepatitis delta virus ribozyme, which consists of three RNA oligomer strands

Properties of a hepatitis delta virus (HDV) RNA ribozyme system, which consists of three RNA oligomer strands (substrate 8-mer; enzyme 16-mer plus 35-mer) and contains a hybrid sequence of genomic and antigenomic RNA cores, are reported. Effects of Mg2+ concentration, divalent metal ion species, pH, and temperature on the cleavage activity were examined. The substrate cleavage activity increased with increasing Mg2+ concentration (0-100 mM). Ca2+ and Mn2+ ions were the most effective divalent cations and Mg2+ was less effective. The cleavage activity increased with increasing pH (5-7.5). The optimum temperature for the cleavage activity was 25-40 degrees C. The Mg2+ concentration, pH and temperature dependencies are different from those reported for the single-strand ribozymes (about 90-mer) although the divalent metal ion preference is very similar. Conformational change induced by Mg2+ ion titration was monitored by CD. The CD data and the activity-Mg2+ concentration data were analyzed by curve-fitting analysis using equations derived for multiple metal ion binding mechanisms. The data can be explained by a model in which three Mg2+ ions bind to one ribozyme unit.

Genetic polymorphism of 5,10-methylenetetrahydrofolate reductase (MTHFR) as a risk factor for coronary artery disease

BACKGROUND

Epidemiological studies have identified hyperhomocyst(e)inemia as an independent risk factor for coronary artery disease (CAD). Recently, the alanine/valine (A/V) polymorphism of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene, one of the key enzymes catalyzing remethylation of homocysteine, has been reported. The VV genotype correlates with increased plasma homocyst(e)ine levels as a result of the reduced activity and increased thermolability of this enzyme. In this study, we examined the distribution of the MTHFR genotypes in Japanese men and the association between the VV genotype and CAD.

METHODS AND RESULTS

The diagnoses of CAD of all the studied patients were confirmed by coronary angiography. The MTHFR genotype was analyzed by PCR followed by HinfI digestion. In 778 healthy male subjects, the frequency of the V allele was 0.33, comparable to that in a French Canadian population. In 362 patients with CAD, the VV genotype was significantly more frequent than in control subjects (16% versus 10%, P=.0067). The association of the VV genotype with CAD was further increased in patients with > or = 99% stenotic lesions (18%, P=.0010), whereas no significant association with the VV genotype was observed in patients without a > or = 99% stenosis. When the genotype frequency was compared among patients with different numbers of stenotic coronary arteries, the frequency of the VV genotype was significantly higher in patients with triple-vessel disease (26%) than in patients with single- or double-vessel disease (15% and 14%, respectively).

CONCLUSIONS

The VV genotype of MTHFR was also common in the Japanese population and was significantly associated with CAD. The frequency of this genotype in particular was correlated with the severity of disease. The VV genotype associated with a predisposition to increased plasma homocyst(e)ine levels may represent a genetic risk factor for CAD.

Physiological role of brain endothelin in the central autonomic control: from neuron to knockout mouse

Although endothelin (ET) was discovered as a potent vascular endothelium-derived constricting peptide, its presumed physiological and pathophysiological roles are now considered much more diverse than originally though. Endothelin in the brain is thought to be deeply involved in the central autonomic control and consequent cardiorespiratory homeostasis, possibly as a neuromodulator or a hormone that functions locally in an autocrine/paracrine manner or widely through delivery by the cerebrospinal fluid (CSF). This notion is based on the following lines of evidence. (1) Mature ET, its precursors, converting enzymes, and receptors all are detected at strategic sites in the central nervous system (CNS), especially those controlling the autonomic functions. (2) The ET is present in the CSF at concentrations higher than in the plasma. (3) There is a topographical correspondence of ET and its receptors in the CNS. (4) The ET is released by primary cultures of hypothalamic neurons. (5) When ET binds to its receptors, intracellular calcium channels. (6) An intracerebroventricular or topical application of ET to CNS sites elicits a pattern of cardiorespiratory changes accompanied by responses of vasomotor and respiratory neurons. (7) Recently generated knockout mice with disrupted genes encoding ET-1 exhibited, along with malformations in a subset of the tissues of neural crest cell lineage, cardiorespiratory abnormalities including elevation of arterial pressure, sympathetic overactivity, and impairment of the respiratory reflex. Definitive evidence is expected from thorough analyses of knockout mice by applying conventional experimental methods.

A role for macrophage scavenger receptors in atherosclerosis and susceptibility to infection

Macrophage type-I and type-II class-A scavenger receptors (MSR-A) are implicated in the pathological deposition of cholesterol during atherogenesis as a result of receptor-mediated uptake of modified low-density lipoproteins (mLDL). MSR-A can bind an extraordinarily wide range of ligands, including bacterial pathogens, and also mediates cation-independent macrophage adhesion in vitro. Here we show that targeted disruption of the MSR-A gene in mice results in a reduction in the size of atherosclerotic lesions in an animal deficient in apolipoprotein E. Macrophages from MSR-A-deficient mice show a marked decrease in mLDL uptake in vitro, whereas mLDL clearance from plasma occurs at a normal rate, indicating that there may be alternative mechanisms for removing mLDL from the circulation. In addition, MSR-A-knockout mice show an increased susceptibility to infection with Listeria monocytogenes or herpes simplex virus type-1, indicating that MSR-A may play a part in host defence against pathogens.

Spontaneous haemothorax caused by costal exostosis

We report a case of spontaneous haemothorax in a 19 year old boy with an exostosis of the left second rib. It may have been caused by nontraumatic rupture of markedly dilated pleural vessels, as a result of long-standing friction between the exostosis and the pleura. This is the first report of spontaneous haemothorax, without penetrative injury to the pleura or the diaphragm, in a patient with hereditary multiple exostosis.

Spontaneous haemothorax caused by costal exostosis

We report a case of spontaneous haemothorax in a 19 year old boy with an exostosis of the left second rib. It may have been caused by nontraumatic rupture of markedly dilated pleural vessels, as a result of long-standing friction between the exostosis and the pleura. This is the first report of spontaneous haemothorax, without penetrative injury to the pleura or the diaphragm, in a patient with hereditary multiple exostosis.

Structural properties and RNA-binding activities of two RNA recognition motifs of a mouse neural RNA-binding protein, mouse-Musashi-1

mouse-Musashi-1 (m-Msi-1) is an RNA-binding protein, abundantly expressed in the developing mammalian central nervous system (CNS). m-Msi-1 contains two RNA recognition motifs (RRMs). In this study, we found that the N-terminal RRM of m-Msi-1 (MMA) binds strongly to poly(G) and weakly to poly(U) in a way similar to that of the full-length m-Msi-1 protein characterized previously. The C-terminal RRM of m-Msi-1 (MMB), however, does not bind to RNA. In addition, the circular dichroism (CD) spectra of the two RRMs showed that the alpha-helical content of MMA is significantly higher than that of MMB, indicating that some differences in the secondary structure may be responsible for the distinct RNA binding properties of MMA and MMB.

Properties of a hammerhead ribozyme with deletion of stem II

The properties of a mutant hammerhead ribozyme system, which consists of two RNA oligomer strands and in which stem II is deleted (replaced with a UUUU loop), are described. The effects of temperature, pH, and metal ions on the cleavage reaction were similar to those for the parent ribozyme with stem II. The mutant ribozyme showed a much lower cleavage rate (kcat = 0.04 min-1) in the presence of 10 mM MgCl2, where the parent ribozyme showed full cleavage activity. However, increasing the concentration of MgCl2 from 10 to 100 mM restored the cleavage activity of the mutant ribozyme to the original level (kcat = 0.2 min-1). CD titration experiments with MgCl2 using a noncleavable substrate were carried out. Deletion of stem II resulted in an about 20-fold reduction of the apparent Mg2+ binding affinity when the Mg2+ concentrations of half-saturation are compared. The results were analyzed by curve-fitting analysis and compared with those for the parent ribozyme. The analysis showed that the Mg2+ concentration dependence data in CD and cleavage experiments for the mutant enzyme can be explained by a two Mg2+ ion binding mechanism. These results that stem II is important for maintaining the conformation of the catalytic core suitable for Mg2+ binding.

Germ-line contribution of embryonic stem cells in chimeric mice: influence of karyotype and in vitro differentiation ability

The effect of the karyotype and the ability to differentiate in vitro upon germ-line transmission by A3-1 embryonic stem (ES) cells in chimeric mice were examined. Germ-line transmission was confirmed in ES cells exhibiting 38% and more of the normal karyotype, but no chimeric mice and/or germ-line transmitters were observed regardless of the karyotype when the cystic embryoid body (CEB) was formed on day 8 and later in the suspension culture. Germ-line transmission of the ES cells was not significantly influenced by formation of the simple embryoid body (SEB). Germ-line transmitters were preferentially observed in chimeras when the ES cell contribution to coat color was markedly increased, but this contribution to coat color varied regardless of the karyotype or in vitro differentiation ability. These results suggest that A3-1 ES cells which exhibit CEB at 7 days after suspension culture and approximately 40% of normal karyotype are capable of germ-line transmission in chimeric mice.