Mapping of the catalytic and epitopic sites of human CD38/NAD+ glycohydrolase to a functional domain in the carboxyl terminus

We reported that 1) ecto-NAD+ glycohydrolase (NADase) activity induced upon differentiation of HL-60 cells is localized on the extracellular carboxyl-terminal side of CD38 and that 2) CD38 ligation by specific mAbs is followed by protein tyrosine phosphorylation in the cells. The strategy selected for identifying the relevant catalytic domains of the molecule relies upon the production in COS-7 cells of carboxyl-terminal deletion mutants of CD38. The mutants with fewer than 15 amino acids deleted at the carboxyl terminus of the 300-amino acid wild-type molecule maintained NADase activity, whereas those with more than 27 amino acids deleted did not. The general inference is that the carboxyl-terminal 273-285 sequence bears the site of enzyme activity. Introduction of site-directed mutation of a conserved cysteine residue (Cys275), located in the 273-285 sequence, completely abolished NADase activity. The second issue resolved in this work is the definition of an epitope of the agonistic anti-CD38 mAbs. To this aim, a panel of selected anti-CD38 mAbs was tested using these mutants and various CD38 fragments as the target in immunoblot analyses. All of the epitopes recognized by mAbs inducing protein tyrosine phosphorylation were mapped on an identical site containing the carboxyl-terminal sequence of 273-285. The conclusion is that the discrete carboxyl-terminal sequence identified in the present study not only plays a key role in its ecto-NADase activity, but actually constitutes the epitopes exploited by the agonistic anti-CD38 mAbs for transmembrane signaling.

Mapping of the catalytic and epitopic sites of human CD38/NAD+ glycohydrolase to a functional domain in the carboxyl terminus

We reported that 1) ecto-NAD+ glycohydrolase (NADase) activity induced upon differentiation of HL-60 cells is localized on the extracellular carboxyl-terminal side of CD38 and that 2) CD38 ligation by specific mAbs is followed by protein tyrosine phosphorylation in the cells. The strategy selected for identifying the relevant catalytic domains of the molecule relies upon the production in COS-7 cells of carboxyl-terminal deletion mutants of CD38. The mutants with fewer than 15 amino acids deleted at the carboxyl terminus of the 300-amino acid wild-type molecule maintained NADase activity, whereas those with more than 27 amino acids deleted did not. The general inference is that the carboxyl-terminal 273-285 sequence bears the site of enzyme activity. Introduction of site-directed mutation of a conserved cysteine residue (Cys275), located in the 273-285 sequence, completely abolished NADase activity. The second issue resolved in this work is the definition of an epitope of the agonistic anti-CD38 mAbs. To this aim, a panel of selected anti-CD38 mAbs was tested using these mutants and various CD38 fragments as the target in immunoblot analyses. All of the epitopes recognized by mAbs inducing protein tyrosine phosphorylation were mapped on an identical site containing the carboxyl-terminal sequence of 273-285. The conclusion is that the discrete carboxyl-terminal sequence identified in the present study not only plays a key role in its ecto-NADase activity, but actually constitutes the epitopes exploited by the agonistic anti-CD38 mAbs for transmembrane signaling.

Signal transduction via the CD38/NAD+ glycohydrolase

The human cell surface CD38 molecule is a 46-kDa type-II transmembrane glycoprotein with a short N-terminal cytoplasmic domain and a long Cys-rich C-terminal extracellular one. We previously demonstrated that an ecto-form NAD+ glycohydrolase (NADase) activity induced by all-trans retinoic acid in HL-60 cells is due to the extracellular domain of CD38. In the present study, we investigated a possible signal transduction mediated through CD38 in the retinoic acid-differentiated HL-60 cells with anti-CD38 monoclonal antibodies (mAbs). The addition of selected anti-CD38 mAbs to the cells induced rapid tyrosine phosphorylation of the cellular proteins with the molecular weights of 120,000, 87,000 and 77,000; the phosphorylated 120-kDa protein was identified as the c-cbl proto-oncogene product, p120c-cbl. Furthermore, the phosphorylated p 120c-cbl associated with the 85-kDa subunit of phosphatidylinositol 3-kinase. To determine the relationship between the amino acid sequence responsible for the NADase activity and epitopes recognized by the stimulatory mAbs, we produced its carboxy-terminal deletion mutants in COS-7 cells. The mutants with less than 15 amino acids deleted from the carboxyl terminus of the 300-amino acid wild-type molecule still maintained NADase activity, but those with more than 27 amino acids deleted did not. Introduction of site-directed mutation of a cysteine residue (Cys275), located in the 273-285 sequence, completely abolished the NADase activity. These CD38 mutants were also used for an epitope mapping of anti-CD38 mAbs. All the epitopes recognized by the mAbs inducing the tyrosine phosphorylation were mapped on the same Cys275-containing sequence of 273-285. Thus, the discrete carboxy-terminal sequence not only plays a key role in its ecto-NADase activity, but also contains the epitopes of the agonistic anti-CD38 mAbs for the transmembrane signaling. We also found that the agonistic mAbs markedly potentiate superoxide generation induced by the stimulation of G protein-coupled chemotactic receptors. Our results suggested that the stimulation of CD38 might generate an accessory signal(s) to enhance the G protein-mediated signaling, probably though the protein-tyrosine phosphorylation.

[A case of congenital tricuspid regurgitation associated with atrial septal defect and peripheral pulmonary stenosis]

This report describes a 5-year-old girl with congenital tricuspid regurgitation associated with an atrial septal defect and peripheral pulmonary stenosis. The girl was diagnosed with the heart murmur at birth and recently developed the cardiomegaly. Cardiac echocardiography and catheterization showed severe tricuspid regurgitation, an atrial septal defect of the secundum type and peripheral pulmonary stenosis. In the operative findings, the tricuspid annulus was dilated to 33 mm in diameter, and leaflets were attached normally to the antomic annulus. There was a large cleft of the anterior leaflet of the tricuspid valve. Suture of the cleft and annuloplasty of the tricuspid valve, suture closure of the atrial septal defect and patch dilatation of peripheral pulmonary stenosis were successfully performed. Including this case, 19 other cases with congenital tricuspid regurgitation undergoing surgery were reported to date.

[A case of malignant lung fibrous histiocytoma]

Malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma in adults. However primary MFH of the lung is very rare and only a few cases have been reported in the literature. A 79-year-old man complained of coughing and was treated at our hospital. The chest X-ray and CT scan showed a mass shadow in left lung. He underwent partial resection of the left upper lobe (S 5). No other abnormal lesions were detected in the abdomen or extremities, and the tumor was diagnosed as malignant fibrous histiocytoma (MFH) of the lung. He has been well for 18 months since the operation.

[A case of left ventricular myxoma]

Left ventricular myxoma is very rare, and only 37 cases have been reported at present time. We here report a case of surgical extirpation of a left ventricular myxoma arising from the septal wall of the left ventricule. A 74-year-old woman was examined by transesophageal echocardiography because of palpitation. It revealed a small mass in the left ventricular cavity. This mass was then diagnosed and confirmed as a myxoma by echocardiogram, CT and MRI. MRI imaging showed the intensity of the myxoma to be higher than that of the myocardium. The myxoma was removed by transaortic approach using extracorponeal circulation. The grayly gelatinous mass was 11 x 12 x 12 mm and weighed 0.6 g. It was diagnosed as a myxoma pathohistologically. The patient recovered uneventfully and was discharged four weeks after the operation.

Analysis of PCR microchimerism induced by intrathymic inoculation of donor alloantigens in rats

Intrathymic injection of donor alloantigens (splenocytes) was performed in rat heart transplantation to induced tolerance. In our experimental protocol, male (BN rats, RT1n) heart allografts were transplanted to female (LEW rats, RT1(1)) recipients in order to detect the existence of Y-chromosomes in recipients' tissues using the polymerase chain reaction (PCR) after the establishment of microchimerism. The mean survival time (MST) of male heart allografts was prolonged by the thymic injection protocol. PCR analysis of the Y-chromosomes of these recipients showed that splenocytes inoculated into the thymus still remained after as long as 30 days, while none of the cells that originated from the donor were never detected in the peripheral blood. On the other hand, our previous study demonstrated that the donor-specific Y-chromosomes could be detected in all the tissues of the females (peripheral blood, lymph nodes, spleen, and liver) except for thymus, of the sex-mismatched rat liver transplantation without thymic injection. Completely inconsistent results were deduced from two of our experiments, but the present study demonstrated that thymic clonal deletion played a major role in the prolongation of allograft survival after intrathymic injection of donor alloantigens.

HLA-DR8 subtyping by polymerase chain reaction (PCR)-DNA conformation polymorphism (DCP) analysis: a simple and practical genotyping method

Two hundred Japanese panels were serologically typed for human leukocyte antigen (HLA) - DR to assign 65 HLA-DR8 haplotypes, which were then subdivided into two genotypes, i.e., DRB1*0802 and DRB1*0803, by a polymerase chain reaction (PCR)--based, simple, and practical method. The panels possessing DR8 specificity were firstly subjected to PCR with a couple of primers specifically to amplify their DR52 associated group--DRB1 genes. PCR products were then denatured in the presence of formamide, electrophoresed in a non-denaturing polyacrylamide gel, and visualized by silver staining. The same DRB1 products of these samples were also mixed with the DRB1*1302, and simultaneously analyzed by the same procedure. Electrophoretic mobilities of the samples were compared with those of the typing standards to genotype their DR8--DRB1 alleles by using the characteristic polymorphism in the single-stranded DNAs and the heteroduplexes. This method, designated PCR--DNA conformation polymorphism (DCP) analysis, allowed for genotyping of the DR8-DRB1 alleles without using sequence-specific oligonucleotide probes (SSOP) or restriction endonucleases. The entire process after PCR was completed within a few hours. The tested panels were also genotyped for DRB1 gene by the PCR-SSOP method for comparison with results obtained by the PCR-DCP method. Satisfactory coincidence was achieved and it represented how accurately the new system genotyped DRB1*0802 and DRB1*0803. PCR-DCP analysis was thus shown to be practical and useful for subtyping of serologically defined DR8 specificities.

HLA-A and -B genotyping in living related one haploidentical kidney

Sixty-five haplo-identical living-related renal transplant pairs were subjected to comparative studies for HLA class-I typing suitability between the DNA and serological methods. Our HLA-A genotyping method was highly resolutive and allowed assigning 33 serologically blank specificities and subdividing some HLA-A serological specificities, of which A2 discrimination was considered to be indispensable for the matching analysis because of its high frequency among Japanese. Our HLA-B genotyping method made it possible to identify the 17 serologically blank specificities despite their "low resolutive" capacities. Analysis of 14 DRB1-compatible pairs suggested that HLA-A and -B compatibilities had beneficial effects on the long term graft survival. It was concluded that HLA-A and -B should be genotyped for the matching analysis of the kidney transplant pairs to obtain satisfactory graft outcome.

The effects of N-methyl-D-aspartate (NMDA) and its competitive antagonist, 3-(2-carboxypiperazine-4-yl)propyl-1-phosphonic acid (CPP), injected into caudate-putamen on kindled amygdaloid seizures in rats

N-methyl-D-aspartate (NMDA) is an agonist of NMDA receptors and 3-(2-carboxypiperazine-4-yl)propyl-1-phosphonic acid (CPP) is an NMDA receptor antagonist. NMDA (1 or 2 nmol per side) or CPP (2.5 or 10 nmol per side) was injected into the bilateral caudate-putamen of amygdaloid-kindled rats. In addition, CPP (10 nmol) was ipsilaterally or contralaterally injected into the unilateral caudate-putamen. Either 20 min after NMDA or 60 min after CPP, the kindled amygdala was stimulated at the generalized seizure triggering threshold. In a few animals tested, injection of NMDA into the bilateral caudate-putamen produced transient spiking activity, with no clinical manifestations. This feature began about 5 min after the injection and lasted about 10 s. When these animals were excluded from the statistical analysis, NMDA in the caudate-putamen showed a weak and non-significant anticonvulsant action. Injection of CPP into the bilateral caudate-putamen caused no ictal change, but markedly suppressed the kindled seizures. Injection of CPP into the unilateral caudate-putamen, regardless of the site, did not cause any ictal change, or affect the stimulation of the amygdala. These findings suggest that: (1) NMDA receptors in the caudate-putamen facilitate the development of kindled amygdaloid seizures; (2) activation of NMDA receptors in the bilateral, but not in the unilateral, caudate-putamen is required for the generalization and expression of kindled amygdaloid seizures.

[Keratitis and corneal edema associated with levodopa use--a case report]

We report a patient who developed keratitis and corneal edema during treatment with carbidopa-levodopa. The patient was a 34-year-old woman who complained of apraxic gait after anoxic brain damage caused by ventricular arrhythmia. She had difficulty in walking. While doses of droxidopa, flecainide acetate and amantadine HCl were kept at the same levels as before several weeks, administration of carbidopa-levodopa was gradually increased from an initial dose of 100 mg per day to 300 mg per day over a period of 10 days in an attempt to relieve her apraxic gait. Ten days after initiation of treatment with carbidopa-levodopa, her postural instability and unsteady gait slightly improved. However, after 8 days of treatment with carbidopa-levodopa, she complained of blurred vision. Ophthalmologic examination showed keratitis (corneal endothelitis) and corneal edema. After stopping carbidopa-levodopa, the keratitis dramatically improved. Cessation of the drug therapy resulted in a return of vision to normal levels by the 7th day. Although there had been no previous reports of corneal lesion caused by levodopa, we suspected that keratitis and corneal edema were associated with carbidopa-levodopa use, especially in combination treatment with flecainide acetate, and amantadine HCl. The process was reversible and presumably could have been prevented by a shorter term of medication.

Stimulation of ADP-ribosyl cyclase activity of the cell surface antigen CD38 by zinc ions resulting from inhibition of its NAD+ glycohydrolase activity

The lymphocyte cell surface antigen, CD38, which has an amino acid sequence similar to Aplysia ADP-ribosyl cyclase, catalyzes not only the hydrolysis of NAD+ and 1-(5-phospho-beta-D-ribosyl) adenosine 5'-phosphate cyclic anhydride (cyclic ADP-ribose) but also the formation of cyclic ADP-ribose from NAD+. To characterize the bifunctional enzyme properties, we produced the recombinant CD38 fused with a maltose-binding protein (MBP-CD38). Zinc ions stimulated the ADP-ribosyl cyclase activity of MBP-CD38, but inversely inhibited its NAD+ glycohydrolase activity which was approximately 100-fold dominant to the cyclase activity in the absence of Zn2+. Such dual effects of Zn2+ were also observed in the native membrane-bound CD38 of HL-60 cells which had been caused to differentiate by retinoic acid. Zinc ions inhibited the NAD+ glycohydrolase reaction catalyzed by MBP-CD38 in an uncompetitive manner, whereas they enhanced the ADP-ribosyl cyclase reaction without affecting the Km value for NAD+. There was an increase in the fluorescence intensity of a hydrophobic fluorescent probe, 8-anilino-1-naphthalenesulfonate, in the presence of MBP-CD38. The fluorescence increase was further enhanced by the addition of Zn2+ with a shift in the maximum emission wavelength from 484 nm to 470 nm, suggesting that Zn2+ caused conformational changes of MBP-CD38. These results indicate that Zn2+ directly interacts with CD38 to stimulate its ADP-ribosyl cyclase with inhibition of its NAD+ glycohydrolase, probably due to prevention of the access of water molecule to an intermediate of the enzymesubstrate complex.

[Clinical results of directional peripheral atherectomy]

I will report clinical results of directional peripheral atherectomy (DPA). DPA was performed in 81 lesions in 57 cases in our department in the period ending February 1996 (56 men and one women, age; 24-85 years old, and mean age; 67 years old). 56 stenotic lesions and 25 complete occlusive lesions were observed. Simpson AtherotrackTM from six to nine Fr was used according the degree of lesions. In the complete occlusive or severe stenotic lesions DPA was carried out only after laser angioplasty (LAP) by using Nd-YAG laser. Initial clinical success was defined as < 30% residual stenotic rate by arteriography. In cases with more than 30% residual stenosis, we performed reDPA, balloon angioplasty or stent implantation. The initial success rate was 98% in the stenotic group and 96% in the occlusive group. Five complications occurred and all complications were minor dissection caused by minor dissection caused by LAP. The late success rate was 86% in the stenotic group and 86% in the occlusive group (observation period; 1-46 mena; 28 months). This new technique might have further clinical application with improvement of the initial and long patency rate.

Increase in ADP-ribosyltransferase activity of rat T lymphocyte alloantigen RT6.1 by a single amino acid mutation

A family of glycosylphosphatidylinositol-linked ADP-ribosyltransferases, of which cDNAs were cloned from various mammalian cells, possess a common Glu-rich motif (EEEVLIP) near their carboxyl termini. Although the first Glu in the common motif is replaced by Gln (Q207EEVLIP) in rat T lymphocyte alloantigens RT6.1 and RT6.2, the two RT6s appear to have both activities of NAD+ glycohydrolase and ADP-ribosyltransferase to a lesser extent. To investigate the significance of the Glu-rich motif in the two enzyme activities, we produced a mutant RT6.1 (Q207E), in which Gln207 was replaced by Glu, together with wild-type RT6s, in Escherichia coli. Kinetic analysis revealed that there were no marked differences in the Vmax and Km values of NAD+ glycohydrolases among the three recombinant proteins. The recombinant RT6.1 and RT6.2 displayed extremely low auto-ADP-ribosylation, although the latter modification was somewhat higher than the former. In contrast, much greater auto-modification was observed for the Q207E mutant. Moreover, the mutant could effectively ADP-ribosylate agmatine as a substrate. Thus, the single amino acid mutation of RT6.1 caused a marked increase in its ADP-ribosyltransferase activity, indicating that the Glu-rich motif near the carboxy terminus plays an important role in the enzyme activity.

[Continuous systemic venous oxygen saturation monitoring immediately after Fontan procedure]

Changes in cardiac output (CO), systemic venous oxygen saturation (SvO2), systemic oxygen consumption, and urinary output immediately after Fontan procedure were measured in 10 patients at the intensive unit (ICU) to assess the effects of aorusal from anesthesia, hypothermic management, and respiratory condition. The measurements were taken at the following phases; phase A in deep sedation under hypothermia (33-35 degrees C rectal temperature) and controlled ventilation; phase B in mild sedation under normothermia and controlled ventilation; phase C when awake under normothermia and assisted ventilation; phase D when awake under assisted ventilation; phase D when awake under normothermia immediately after extubation; and phase E 24 hours after extubation. Oxygen delivery (O2 Del.) and fractional oxygen fractions were calculated in each phase. Two patients whose SvO2 values were below 55% during the postoperative course needed reoperation for atrioventricular valve regurgitation in one case for PV stenosis in the other case. CO increased significantly (p < 0.05) after extubation (phase D), compared with that of controlled ventilation (phase B). Under hypothermia (phase A), urinary output was relatively higher with lower CO. There was a significant correlation between SvO2 and CO (R = 0.61) in phase A, however there was no correlation in phase E. Fractional oxygen extraction in phase A was significantly lower than in phase B. In conclusion, the continuous SvO2 measurements reflected real-time changes in cardiac output in the immediate post-Fontan patients. Induced hypothermia was beneficial in increasing urinary output presumably through the correction of maldistribution of cardiac output in post-Fontant patients. Arousal from anesthesia and spontaneous ventilation seemed advantageous for increasing cardiac output, hence, early extubation should be encouraged in the management of post-Fontan patients.

Induction of CD38/NADase and its monoclonal antibody-induced tyrosine phosphorylation in human leukemia cell lines

We previously reported that CD38 characterized as an ecto-enzyme of NAD+ glycohydrolase (NADase) was specifically induced by retinoic acid (RA) in human promyelocytic leukemia HL-60 cells and that anti-CD38 monoclonal antibody (mAb) induced tyrosine phosphorylation of cellular proteins in the RA-differentiated cells. In the present study, we found that CD38/NADase was induced in human monocytic leukemia THP-1 cells not only by RA but also by dibutyryl cAMP, which had no effect on the induction of CD38 in HL-60 cells. Similarly in the RA-differentiated HL-60 cells, tyrosine phosphorylation by anti-CD38 mAb was also observed in the CD38-expressing THP-1 cells, regardless of whether CD38 was induced by RA or dibutyryl cAMP. Such tyrosine phosphorylation was, however, not observed in human lymphoblastic leukemia Jurkat cells which had been treated by RA to produce CD38. Thus, the induction of CD38/NADase appeared to be not limited for RA-dependent differentiation and not always linked to protein-tyrosine phosphorylation in human leukemic cell lines.

[Total cavopulmonary connection using a knitted dacron prosthesis impregnated with gelatin (GELSEAL) as an intracardiac conduit]

It is important to find a suitable vascular prosthesis as an intracardiac conduit for a total cavopulmonary connection because of the need for long-term patency. A 7-year-old girl with a double outlet of right ventricle, hypoplastic left ventricle, pulmonary atresia and single atrium with azygos connection underwent a total cavopulmonary connection using a knitted dacron prosthesis impregnated with gelatin (GELSEAL) as an intracardiac conduit. Her postoperative course was uneventful. GELSEAL is soft, easy to hand and effective at preventing blood loss. The conduit is also expected to have long-term patency because of good healing with thin and uniform pseudointimal formation. However, long-term patency especially in the right side of the heart is still unknown. She should be followed with close anticoagulant therapy and careful observation.

Assessment of microchimerism in rat liver transplantation by polymerase chain reaction

Mixed chimerism has been demonstrated in organ transplant recipients surviving over a long period. However, little is known about the fate and movements of donor cells following liver transplantation. In this study, using rat male-to-female liver transplantation, we assessed microchimerism by semiquantitative polymerase chain reaction (PCR). A PCR specific for the Y-chromosome (sex-determining region Y [Sry]) allowed the distinction of small amounts of male cells in a large excess of female cells. Nonimmunosuppressed Lewis recipients of Lewis liver grafts survived >60 days, and donor cells were detected in peripheral blood up to day 60 in four of six recipients. All immunosuppressed Lewis recipients survived for 60 days, and the donor cells were detected up to day 60. Semiquantitative PCR demonstrated that in immunosuppressed Lewis recipients surviving >60 days with no acute rejection episode, the donor-to-recipient cell ratio remained >1:1,000. In nonimmunosuppressed Lewis recipients of ACI liver allografts, donor cells in peripheral blood decreased rapidly by day 7. In immunosuppressed Lewis recipients of ACI liver allografts, donor cells were detected for longer periods, in proportion to the amount and duration of FK506 (Fujisawa Pharmaceutical Co., Osaka, Japan) administered. However, in recipients with deteriorating function due to ongoing rejection, small amounts (0.01 percent) of donor cells were detected. Our results indicate that the Sry-specific PCR is useful for assessing microchimerism following rat liver transplantation, and demonstrate correlation between microchimerism and graft outcome; high-level microchimerism (>O.l percent) correlated well with graft acceptance, whereas low-level microchimerism (<O.01 percent) did not.

Prolonged and extensive IgG immunoreactivity after severe fluid-percussion injury in rat brain

The relationships between protein extravasation, morphological changes in neurons, and reactive changes in axons were evaluated in rats subjected to right lateral fluid-percussion injury to the brain (4.8-5.6 atm, 20 ms). Serial sections of the brain were immunostained with antibodies to rat immunoglobulin G (IgG) and 68-kDa neurofilament at 1 h to 2 weeks after injury or sham injury. Ischemic changes in neurons were noted in the injured cortex at 6-48 h after injury, and macroscopic hemorrhages were noted in the right corpus callosum and external capsule at 1 h to 1 week after injury. Extracellular IgG immunostaining was observed in the right cortex and right hippocampus at 1 h to 1 week after injury, and in the cortices and hippocampi bilaterally at 2 weeks after injury, but was most prominent in those regions at 24 h after injury. Intracellular IgG staining was noted in the neurons of cortices, hippocampi, brainstem, and cerebellum at 1 h to 2 weeks after injury. The number of IgG immunoreactive neurons was greatest at 1 week after injury. Thickened IgG immunoreactive axons and reactive axonal changes seen with neurofilament immunostaining were both in the similar region of the brainstem at 1 h to 1 week after injury. It appears that prolonged and widespread breakdown of the blood-brain barrier to plasma protein occurs after severe concussive brain injury and that this breakdown is not always accompanied by morphological changes. Intra-axonal IgG immunostaining provides additional clues to the pathogenesis of axonal damage following diffuse brain injury.

Origin of the left coronary artery from the right pulmonary artery

We report the successful surgical treatment of a 12-year-old boy with a rare type of Bland-White-Garland syndrome with mitral regurgitation, in which an anomalous left coronary artery arose from the middle portion of the right pulmonary artery, employing the direct translocation of the left coronary artery and mitral valvuloplasty.

Identification of a novel isoform of estrogen receptor, a potential inhibitor of estrogen action, in vascular smooth muscle cells

Clinical and experimental studies showed that estrogen has antiatherogenic effects. We previously demonstrated that the estrogen receptor (ER) mRNA and protein are expressed in vascular smooth muscle cells (VSMC) derived from rat aorta. Here, the expression of isoforms of the ER was examined in VSMC. Reverse transcriptase-polymerase chain reaction using specific primers for rat ER cDNA was performed from RNA of rat VSMC. This revealed the existence of ER cDNA that is shorter than the wild-type ER cDNA. Sequencing of the amplified products identified three isoforms of the ER and the wild-type ER. These ER mRNA isoforms lacked the region corresponding to exon 4, exon 4 and 5, and exon 3 and 4. Therefore, they were designated as ERdelta4 isoform, ERdelta4/5 isoform and ERdelta3/4 isoform, respectively. Chloramphenicol acetyltransferase assay was performed with these ER isoforms constructed into the expression vector and the reporter plasmid containing the estrogen responsive element. The assay showed that these ER isoforms lost estrogen-dependent transactivation activities and that ERdelta4/5 isoform has a inhibitory effect on normal estrogen action when it was cotransfected with the wild-type ER. These ER isoforms might be involved in the regulation of VSMC by estrogen.

Tyrosine phosphorylation of the c-cbl proto-oncogene product mediated by cell surface antigen CD38 in HL-60 cells

The human cell surface antigen CD38 is a 46-kDa type II transmembrane glycoprotein with a short N-terminal cytoplasmic domain and a long Cys-rich C-terminal extracellular one. We demonstrated previously that the extracellular domain of CD38 has NAD+ glycohydrolase (NADase) activity and that the ecto-form NADase activity induced in HL-60 cells during cell differentiation by retinoic acid is due to CD38. In the present study, we investigated the intracellular signaling mediated by CD38 in retinoic acid-differentiated HL-60 cells with an anti-CD38 monoclonal antibody. The addition of anti-CD38 monoclonal antibody to the cells induced rapid tyrosine phosphorylation of the cellular proteins with molecular weights of 120,000, 87,000, and 77,000. An increase in tyrosine kinase activity in the anti-phosphotyrosine immunoprecipitates of the cells was also observed after the addition of anti-CD38 monoclonal antibody. Moreover, one of the prominent tyrosine-phosphorylated proteins stimulated by the anti-CD38 monoclonal antibody was identified as the c-cbl proto-oncogene product, p120c-cbl. These results indicated that tyrosine phosphorylation of cellular proteins, including p120c-cbl, is possibly involved in transmembrane signaling mediated by CD38.

A congenitally "poor" pulmonary artery is a major reason for exclusion from Fontan operation

We reviewed the clinical records of 185 patients who were possible candidates for Fontan operation. We did this to clarify whether all patients with suitable anomalies ultimately underwent a Fontan operation. Of the 152 patients with decreased pulmonary blood flow, 38 (26%) did not fulfill the criteria for Fontan operation, and 17 of the 33 patients (52%) with increased pulmonary blood flow (P < 0.01) were excluded as candidates. Of 48 non-candidate survivors, 19 had high pulmonary artery (PA) pressure or resistance and small PA (which we term "poor PA"), 17 had pulmonary hypertension, 6 had a markedly distorted PA, and 6 had severe ventricular dysfunction. A significant proportion of possible candidates with a suitable anomaly ultimately did not undergo a Fontan operation, because of "poor PA", a congenital condition that precluded Fontan operation.

Effects of amino acids on the growth of an anaerobic rumen fungus Neocallimastix sp N 13

The amino acid requirements of Neocallimastix sp N 13 isolated from sheep rumen were studied using supplements containing either ten essential amino acids (10 EAA) or eight nonessential amino acids (8 NEAA), or both (18 AA). Although the fungus could grow in a medium containing ammonium sulphate as the sole source of nitrogen, amino acid supplements, especially 18 AA, greatly stimulated its growth. Omission of the sulphur-containing amino acids (SCAA) from the 18 AA mixture markedly reduced the growth-stimulating effect, and sulphide, but not sulphate, substituted for SCAA only partly compensated for this omission. Omission of aromatic, branched chain, basic, acidic, aliphatic and hydroxy amino acids, and proline, singly or in combination, all reduced fungal growth to some degree as compared with the 18 AA supplement. A three amino acid (leucine, methionine and histidine) supplement was a potent stimulator for the fungus, whereas another three amino acid combination (glutamic acid, methionine and serine) was ineffective. The results indicated that Neocallimastix sp N 13 effectively utilized amino acids for its growth, but the requirements for the different amino acids differed from those of N patriciarum.

Growth hormone-independent expression of insulin-like growth factor I messenger ribonucleic acid in extrahepatic tissues of the chicken

The sex-linked dwarf (SLD) chicken, which lacks GH receptor (GHR), and its normal littermates provide a useful experimental system to investigate GH-dependent cellular responses. The GH dependence of insulin-like growth factor I (IGF-I) expression in tissues was examined in SLD and normal chickens of the Gifu 20 strain. Four weeks after hatching, the most abundant expression of IGF-I messenger RNA (mRNA) was observed in liver of normal chickens, whereas no IGF-mRNA expression was detected in that organ of dwarf chickens. On the contrary, in extrahepatic tissues such as spleen, lung, brain, kidney, heart, intestine, thymus, and muscle, IGF-I mRNA expression was equally observed in normal and GHR-lacking dwarf chickens. In the testis, expression of IGF-I mRNA was enhanced by about 5-fold in dwarf chickens showing an expression level comparable to that in normal liver. On day 16 in the embryonic stage, IGF-I mRNA was expressed in muscle, brain, eye, heart, and lung in both normal and SLD chick embryos. However, no IGF-I mRNA expression was observed in liver or kidney of normal and dwarf chick embryos. These results suggest that in chicken, IGF-I mRNA is expressed in liver in a GH-dependent manner after hatching, whereas in other tissues, mRNA expression is independent of GH and GHR before and after hatching, except for testis, in which GH seems to inhibit IGF-I mRNA expression.

Immunohistochemical detection of activin A in osteoclasts

Production of a member of transforming growth factor-beta (TGF-beta) superfamily, activin A, was examined in the bone tissue by using reverse transcriptase polymerase reaction. As a result, specific bands were detected showing the presence of activin A mRNA in the bone tissues. In order to localize the production site of activin A in the bone tissues, we tried to immunolocalize activin A in fetal mouse calvaria cultured in a medium containing fetal calf serum, 1 alpha-25(OH)2 vitamin D2 and parathyroid hormone. In these cultured calvaria, bone tissues including bone-resorbing osteoclasts in vitro were observed. Positive staining demonstrating the presence of activin A resided inside of the multinucleated cells in the bone resorbing lacunae, suggesting the production of activin A in osteoclasts. Activin A was also localized immunohistochemically in the osteoclast-like multinucleated cells developed in vitro. These results suggest that osteoclast produce activin in the bone tissues and that activin may play some roles by autocrine and/or paracrine manner in bone metabolisms.

Paying for the health and social care of the elderly

The aging population of Japan is causing serious concern among social policymakers. The most urgent issue is to find a way to pay for the health and social care of the frail elderly. After universal coverage of pension and health insurance was achieved, but just before the economic growth rate was considerably slowed, in part, because of the oil crisis, the Japanese government more than doubled pension benefits and made medical care for the elderly free. Since the early 1980s, the government has tried hard to cut and control these benefits, only with moderate success. With a consumption tax rate of only 5%, rather than the proposed 7%, the government is now considering establishing a new health and social care insurance scheme for the elderly to finance the increasing cost of their care.

Expression of aberrantly spliced growth hormone receptor mRNA in the sex-linked dwarf chicken, Gifu 20

The structure and expression of the growth hormone receptor (GHR) gene have been studied in a sex-linked dwarf (SLD) chicken strain, Gifu 20. No gross structural change in the receptor gene was observed by Southern blot analysis, however, a transcript of 5.5 killobases (kb), which was approximately 1 kb larger than the usual chicken full length-GHR mRNA was detected in the dwarf chicken by Northern blot analysis. GHR cDNA was obtained from dwarf chicken liver RNA by reverse transcription-polymerase chain reaction, and nucleotide sequence analysis revealed that it contained an intron sequence of the GHR gene. The unspliced intron showed a single point mutation at the donor site from GT to GC, and an aberrant stop codon was generated in the extracellular domain-coding region. Thus, the mutation resulting in an inappropriate splicing of the GHR gene transcript is considered to be the cause of this dwarf chicken.

[A modified Damus-Kaye-Stansel anastomosis for restrictive bulvoventricular foramen developed 5 years after Fontan procedure]

An one-year old girl, who had pulmonary artery (PA) banding and balloon atrioseptostomy done in the newborn period, underwent modified Fontan procedure on an emergency basis without cardiac catheterization, because of right heart failure. Echocardiogram showed no subaortic stenosis at Fontan procedure. Five years later, subaortic stenosis was documented with a 65 mmHg of ventricular-aortic pressure gradient at catheterization. A modified Damus-Kaye- Stansel (D-K-S) procedure was successfully performed using an end-to-end anastomosis of the distal aorta and a common stump, consisting of previously suture-closed main PA stump and the proximal aorta. At postoperative catheterization, the pulmonary valve was functioning well at LV outlet portion without regurgitation and stenosis. Significant subaortic stenosis may develop after Fontan procedure in patients with morphological narrowing without demonstrable pressure gradient. Such patients should have surgical intervention to the narrowing at the time of Fontan procedure. The modified D-K-S procedure can be an effective procedure to relieve subaortic stenosis after Fontan procedure.

[Surgical treatment of congenital atypical coarctation of the aorta and postoperative management for hypertension]

A 10-year-old boy was admitted to our hospital with severe hypertension due to unusual aortic coarctation at the level of the diaphragm without renal artery stenosis. We made left interior thoracotomy and left para-rectal incision through extraperitoneal approach, and extra-anatomic bypass was established with a 16 mm knitted Dacron graft from the descending aorta to the infrarenal abdominal aorta, under a circulatory assist. Postoperatively, he complained of abdominal pain with residual hypertension and required an intensive anti-hypertensive treatment to avoid intestinal necrosis. Pressure gradient between upper and lower extremities disappeared 3 weeks after repair. High level of plasma renin activity still continued 4.5 months after surgery in spite of oral administration of beta blockade and ACE inhibitor.

Demonstration of isoforms of the estrogen receptor in the bone tissues and in osteoblastic cells

Expression of isoforms of estrogen receptor (ER) was examined in the bone tissues. Reverse transcriptase-polymerase chain reaction ((RT-PCR) using specific primers for rat ER cDNA was performed with total RNA from rat bone tissues. Then, we sequenced the amplified products after cloning and identified two isoforms of the ER and the wild-type ER. One of the ER mRNA isoforms did not have the region corresponding to exon 4 and the other isoform did not have the region corresponding to both exon 3 and exon 4. These isoforms were designated as ER delta 4 isoform and ER delta 3/4 isoform, respectively. The existence of these isoforms was also confirmed by ROS-17/2.8 osteoblastic osteosarcoma cells. Chloramphenicol acetyltransferase assay showed that these isoforms lost estrogen dependent transactivation activities. We suggest that the ER isoforms may play some roles in the bone metabolism in which estrogen is essential to maintain bone density.

[A case of ruptured thoracoabdominal aortic aneurysm complicated with high aortic occlusion]

We report a rare case of 76-year-old man who developed ruptured thoracoabdominal aortic aneurysm complicated with abdominal high aortic occlusion. His left limb was amputated due to Buerger's disease. CT showed that the aneurysm extended from the descending thoracic aorta to the upper part of the abdominal aorta and its had a maximum width of 68 x 83 mm. Angiogram revealed the aortic occlusion at the level of the left renal pelvis. We performed emergency operation, which was aneurysmectomy and replacement with artificial vascular graft, under femoro-femoral and subrenal aortic extracorporeal bypass. Because of the severe calcification at the subrenal aorta and the weak pulsation of the left renal artery, the bypass was placed from the aortic graft to the right lower limb and the left renal artery was reconstructed. Abdominal aortic occlusion might increase his hypertension and might cause aneurysmal change on the proximal aortic wall.

Significance of Thr182 in the nucleotide-exchange and GTP-hydrolysis reactions of the alpha subunit of GTP-binding protein Gi2

The crystal structures of the GTP- and GDP-bound alpha subunits of heterotrimeric GTP-binding proteins were recently determined, and a conserved Thr residue in the G2 (linker 2) region of the alpha subunits, which corresponds to Thr182 in Gi2 alpha, was deduced to interact with the gamma-phosphate of GTP and Mg2+. To investigate biochemically the significance of the Thr residue, we produced a mutant Gi2 alpha, in which Thr182 was substituted for Ala (T182A), in Escherichia coli. The rate of guanosine 5'-(gamma-thio)tri-phosphate (GTP gamma S) binding to T182A was higher than that to the wild-type Gi2 alpha, especially with a high concentration (10 mM) of Mg2+. The rate of dissociation of bound GDP from T182A was also much faster than that from the wild-type with the high Mg2+ concentration. Moreover, T182A had much lower GTPase activity than the wild-type, like the gip mutant (R179C) of Gi2 alpha found in human endocrine tumors. The ability of T182A to interact with beta gamma subunits and membrane-bound receptors was the same as that of the wild-type alpha subunit. T182A could take on a GTP-bound active conformation, as judged from its sensitivity to tryptic digestion. These results indicated that Thr182 plays an important role not only in the Mg(2+)-sensitive GDP-GTP exchange reaction but also in the GTPase activity of Gi2 alpha. The T182A mutant of Gi2 alpha, characterized by the faster GDP release and the slower GTP hydrolysis, would be a novel mutant that retains the ability to interact with receptors and beta gamma subunits.

[Two cases of CA19-9 producing pulmonary papillary adenocarcinoma]

Two cases of CA 19-9 producing pulmonary papillary adenocarcinoma were reported. Pathological examination showed a well differentiated papillary adenocarcinoma with partially bronchiolo-alveolar cell type. Immunohistochemical study showed a positive straining for CA 19-9 on tumor cells. The level of CA 19-9 decreased after lobectomy and anti-cancer chemotherapy using CDDP and VDS. The series of CA 19-9 level is very useful to evaluate the effect of surgery and chemotherapy. Also it is useful to find out the recurrence of carcinoma.

NAD(+)-dependent ADP-ribosylation of T lymphocyte alloantigen RT6.1 reversibly proceeding in intact rat lymphocytes

Rat T lymphocyte alloantigen 6.1 (RT6.1), which was synthesized as the fusion protein with a maltose-binding protein in Escherichia coli, displayed NAD(+)-dependent auto-ADP-ribosylation in addition to an enzyme activity of NAD+ glycohydrolase. Such ADP-ribosylation of RT6.1 was also observed in lymphocytes isolated from rat tissues as follows. When intact rat lymphocytes expressing RT6.1 mRNA were incubated with [alpha-32P]NAD+, its radioactivity was incorporated into a cell surface protein with the M(r) of 31,000. The radiolabeled 31-kDa protein was released from the cell surface by treatment of the cells with phosphatidylinositol-specific phospholipase C and immunoprecipitated with anti-RT6.1 antiserum. The radioactivity incorporated into the 31-kDa protein was recovered as 5'-[32P]AMP upon incubation with snake venom phosphodiesterase and also removed by NH2OH treatment. These results suggested that the NAD(+)-dependent modification of the 31-kDa protein was due to ADP-ribosylation of glycosylphosphatidylinositol-anchored RT6.1 at an arginine residue. When intact lymphocytes, in which RT6.1 had been once modified by [32P]ADP-ribosylation, were further incubated in the absence of NAD+, there was reduction of the radioactivity in the [32P]ADP-ribosylated RT6.1. The reduced radioactivity was recovered from the incubation medium as [32P]ADP-ribose. This reduction was effectively inhibited by the addition of ADP-ribose to the reaction mixture. Moreover, readdition of NAD+ caused the ADP-ribosylation of RT6.1 again. Thus, the ADP-ribosylation of RT6.1 appeared to proceed reversibly in intact rat lymphocytes.

Accumulation of cyclic ADP-ribose measured by a specific radioimmunoassay in differentiated human leukemic HL-60 cells with all-trans-retinoic acid

Cyclic adenosine diphosphoribose (cADPR) is a novel candidate for the mediator of Ca2+ release from intracellular Ca2+ stores. The formation of this cyclic nucleotide is catalyzed by not only Aplysia ADP-ribosyl cyclase but also an ecto-form enzyme of NAD+ glycohydrolase (NADase), which was previously identified as all-trans-retinoic acid (RA)-inducible CD38 in human leukemic HL-60 cells. In the present study, we developed a radioimmunoassay specific for cADPR, by which more than 100 fmol of cADPR could be detected without any interference by other nucleotides. The possible involvement of CD38 in the formation of cellular cADPR was investigated with the radioimmunoassay method. A marked increase in cellular cADPR was accompanied by all-trans-RA-induced differentiation of HL-60 cells. Moreover, a high level of cellular cADPR was observed in other leukemic cell lines, in which CD38 mRNA was expressed. Thus, CD38, which was initially identified as an NADase, appeared to be responsible for the formation of cellular cADPR.