Vesicourethral sphincter dysfunction in ncx deficient mice with an increased neuronal cell number in vesical ganglia

PURPOSE

Ncx/Hox11L.1 knockout mice have a megacolon with an increased number of neuronal cells in the enteric ganglia. Since Ncx/Hox11L.1 is expressed in neuronal cells in the vesical ganglia, we examined lower urinary tract function and the number of neuronal cells in the vesical ganglia in Ncx/Hox11L.1 knockout mice.

METHODS

Female knockout and control mice were investigated in regard to voiding frequency, and cystometry and histological studies were done. The number of neuronal cells in the vesical ganglia was observed by staining with nicotinamide adenine dinucleotide phosphate diaphorase and cuprolinic blue.

RESULTS

In knockout mice voiding frequency was 2-fold and bladder capacity was less than in controls. Although bladder structure was histologically similar in knockout mice and controls, cystometry showed that threshold and remaining pressure was less in knockout mice. Neuronal cells positive for nicotinamide adenine dinucleotide phosphate diaphorase or cuprolinic blue were more numerous in the vesical ganglia of knockout mice than controls. The intraperitoneal injection of a nitric oxide synthase inhibitor increased threshold and remaining pressure on cystometry in knockout mice to the control level.

CONCLUSIONS

The increased number of neuronal cells in the vesical ganglia induces vesicourethral sphincter muscle dysfunction in knockout mice. Since administering a nitric oxide synthase inhibitor somewhat overcomes the dysfunction, the amount of nitric oxide in vesical nerve cells is important for controlling vesicourethral sphincter muscle function.

Transcriptional regulation of memory B cell development

Abstract Antigen-reactive B cells in the spleen of mice immunized with T cell-dependent antigens generate antibody-producing foci in periarteriolar lymphoid sheaths (PALS) or migrate into follicles to form germinal centers. Germinal center B cells clonally expand, have somatic hypermutation in IgV-region genes, are selected by apoptosis on the basis of antigen-specific signals, and differentiate to memory B cells. Two transcription factors (Bcl6 and c-Fos) in B cells play a critical role in the development of germinal centers. (1) Bcl6 is highly expressed in germinal center B cells, and defects in B cells perturb the formation of germinal centers but not that of PALS-associated foci, indicating the essential role of Bcl6 in the differentiation. (2) Overexpression of c-Fos in germinal center B cells induces apoptosis and perturbs the formation of memory B cells. Overexpression of Bcl-2 cannot rescue c-Fos-induced apoptosis in germinal center B cells. Since c-Fos is induced in mature B cells which have reacted with antigens, and clonal deletion of self-reactive B cells is insensitive to overexpression of Bcl-2, c-Fos may play a causal role in the clonal deletion of germinal center B cells. Thus, these factors provide a unique opportunity to investigate the molecular mechanisms of memory B cell development.

Dissection of autophagosome formation using Apg5-deficient mouse embryonic stem cells

In macroautophagy, cytoplasmic components are delivered to lysosomes for degradation via autophagosomes that are formed by closure of cup-shaped isolation membranes. However, how the isolation membranes are formed is poorly understood. We recently found in yeast that a novel ubiquitin-like system, the Apg12-Apg5 conjugation system, is essential for autophagy. Here we show that mouse Apg12-Apg5 conjugate localizes to the isolation membranes in mouse embryonic stem cells. Using green fluorescent protein-tagged Apg5, we revealed that the cup-shaped isolation membrane is developed from a small crescent-shaped compartment. Apg5 localizes on the isolation membrane throughout its elongation process. To examine the role of Apg5, we generated Apg5-deficient embryonic stem cells, which showed defects in autophagosome formation. The covalent modification of Apg5 with Apg12 is not required for its membrane targeting, but is essential for involvement of Apg5 in elongation of the isolation membranes. We also show that Apg12-Apg5 is required for targeting of a mammalian Aut7/Apg8 homologue, LC3, to the isolation membranes. These results suggest that the Apg12-Apg5 conjugate plays essential roles in isolation membrane development.

Testicular germ cell apoptosis in Bcl6-deficient mice

Bcl6 protein has been detected in testicular germ cells, mainly spermatocytes, of normal mice, but its physiological role is largely unknown. The number of spermatozoa in the cauda epididymis of adult Bcl6-deficient (Bcl6−/−) mice is lower than that of Bcl6+/+ mice. We have found numerous apoptotic spermatocytes at the metaphase I stage with induction of Bax protein in adult Bcl6−/− testes. Developmentally, the incidence of germ cell apoptosis of Bcl6−/− mice was similar to that of Bcl6+/+ mice until six weeks of age and increased after eight weeks of age. The incidence of apoptosis in heterozygous Bcl6+/− mice was also higher than that of Bcl6+/+ mice. Since the activated form of p38 MAP kinase was detected in spermatocytes of adult Bcl6−/− mice, the germ cell apoptosis may be induced by stressors. Treatment of testes of adult Bcl6+/+ mice with a mild hyperthermia resulted in germ cell apoptosis predominantly in metaphase I spermatocytes with induction of Bax protein and activation of p38 MAP kinase and this apoptosis mimics that in adult Bcl6−/− mice. Thus, Bcl6 may play a role as a stabilizer in protecting spermatocytes from apoptosis induced by stressors.

[The effects of ACE inhibitor treatment and ACE gene polymorphism on erythropoiesis in chronic hemodialysis patients]

Aggravation of anemia in chronic renal failure patients by angiotensin-converting enzyme inhibitors (ACEIs) has been attributed to the inhibition of angiotensin II which facilitates erythropoietin(Epo) production. This study was aimed at evaluating whether ACEIs aggravate anemia in maintenance hemodialysis patients and to investigate the influence of ACE gene polymorphism on erythropoiesis in these patients. Ninety-one hemodialysis patients were divided into 2 groups, based on whether or not they were administered ACEIs, into the ACEI group(n = 24) and the non-ACEI group(n = 67), and comparisons were made of the doses of recombinant human Epo(rHuEpo) administered, the hematocrit(Hct) and the plasma Epo concentrations. Among the patients in the non-ACEI group, only 17 did not receive rHuEpo, while all of the patients in the ACEI group received rHuEpo. The average dose of rHuEpo was 102.7 +/- 45.4 IU/kg/week in the ACEI group and 57.8 +/- 55 IU/kg/week in the non-ACEI group and the difference between the two groups was statistically significant. A statistically significant difference in the Hct was also observed between the two groups: the mean Hct in the ACEI group was 28.7 +/- 2.9% while that in the non-ACEI group was 31.1 +/- 3.7%. The plasma Epo concentrations were significantly lower in the ACEI group than in the non-ACEI group. No significant differences in the rHuEpo dose and Hct were observed between the three ACE genotype classes in either the ACEI or the non-ACEI group, however, there was a significant difference among the three genotypes in the non-ACEI group in regard to the plasma Epo concentrations; patients with the DD genotype had higher concentrations than those with the DI or II genotypes. These data suggest that anemia in maintenance hemodialysis patients is worsened by ACEIs as a result of the suppression of Epo production. Although it has been suggested that the endogenous Epo concentrations in maintenance hemodialysis patients are associated with ACE gene polymorphism, no significant influence of the ACE genotype on the rHuEpo dose or Hct was evident. Therefore, it is possible that exacerbation of anemia by ACEIs in the patients receiving rHuEpo is a result of an inhibited bone marrow response to Epo.

Cell cycle-dependent regulation of TIAP/m-survivin expression

TIAP, a murine homologue of human survivin, is a member of the inhibitor of apoptosis (IAP) family and is specifically expressed at G2/M phase of the cell cycle. To elucidate regulatory mechanisms of the cycle-dependent expression, we have analyzed the promoter region of TIAP/mouse survivin (m-survivin). The 5'-flanking region of the TIAP/m-survivin gene contained a TATA-less promoter, two AP2 sites, three NF-kB sites, one Sp1 site, many cell cycle-dependent elements (CDEs) and one cell cycle gene homology region (CHR). Primer extension and 5'-rapid amplification of cDNA ends identified one transcription start site at position -100 upstream of the ATG start site (+1). TIAP/m-survivin promoter-luciferase analysis identified a minimal promoter region within the most proximal -271 bp upstream of the ATG start site, and the region between -410 and -272 was critical for the enhancer activity. The combination between the CHR at -51 and the CDE at -57 is also essential for the cell cycle-dependent expression. Mutation of the CDE/CHR element and the enhancer elements may cause disordered expression of TIAP/m-survivin to affect cell survival and oncogenesis.

HCV-core protein accelerates recovery from the insensitivity of liver cells to Fas-mediated apoptosis induced by an injection of anti-Fas antibody in mice

BACKGROUND/AIMS

Hepatitis C virus (HCV) is a major etiologic agent of chronic hepatitis, cirrhosis, and hepatocellular carcinoma. The aim of this study was to elucidate pathological effects of HCV-core protein on liver cells.

METHODS

We have generated transgenic mice carrying HCV-core cDNA (Px-core) and pathologically examined livers of Px-core mice.

RESULTS

HCV-core protein was detectable in livers from lines 5 (C5) and 8 (C8) of Px-core transgenic mice. Since chronic hepatitis and cirrhosis precede hepatocellular carcinoma in patients with HCV infection, we tried to examine the effect of repetitive injection of a small dose of anti-Fas antibody in the transgenic mice. Surprisingly, an initial injection of anti-Fas antibody induced resistance of liver cells to the second injection of anti-Fas antibody in both Px-core and littermate control mice. The insensitivity of liver cells induced in the control mice continued for more than 24 weeks after the first injection but was broken within 1 week after partial hepatectomy. However, the sensitivity was restored in the Px-core mice within 12 weeks after the injection.

CONCLUSION

HCV-core protein in liver cells may affect persistence of Fas-mediated liver cell injury.

Blockade of transforming growth factor beta/Smad signaling in T cells by overexpression of Smad7 enhances antigen-induced airway inflammation and airway reactivity

Transforming growth factor (TGF)-beta has been implicated in immunosuppression. However, it remains obscure whether regulation of T cells by TGF-beta contributes to the immunosuppression in vivo. To address this issue, we developed transgenic mice expressing Smad7, an intracellular antagonist of TGF-beta/Smad signaling, selectively in mature T cells using a plasmid construct coding a promoter element (the distal lck promoter) that directs high expression in peripheral T cells. Peripheral T cells were not growth inhibited by TGF-beta in Smad7 transgenic mice. Although Smad7 transgenic mice did not spontaneously show a specific phenotype, antigen-induced airway inflammation and airway reactivity were enhanced in Smad7 transgenic mice associated with high production of both T helper cell type 1 (Th1) and Th2 cytokines. Thus, blockade of TGF-beta/Smad signaling in mature T cells by expression of Smad7 enhanced airway inflammation and airway reactivity, suggesting that regulation of T cells by TGF-beta was crucial for negative regulation of the inflammatory (immune) response. Our findings also implicated TGF-beta/Smad signaling in mature T cells as a regulatory component of allergic asthma.

Identification of an optimal Ncx binding sequence required for transcriptional activation

The Ncx gene encodes a homeobox containing transcription factor that belongs to the Hox11 gene family. We determined specific Ncx protein binding consensus DNA sequences. Optimal Ncx binding sequences were 5'-CGGTAATTGG-3' (TAAT core) and 5'-CGGTAAGTGG-3' (TAAG core), which coincided with the Hox11 binding sequence. Both Ncx and Hox11 could bind to the TAAT and the TAAG core oligonucleotide in vitro. However, they could efficiently transactivate the reporter plasmid linked to the TAAT core sequence but not to the TAAG core sequence. Thus, Ncx and Hox11 act as transcriptional activators via their target sequence, 5'-CGGTAATTGG-3'.

Precise measurement of dp elastic scattering at 270 MeV and three-nucleon force effects

The cross section, the deuteron vector A(d)(y) and tensor analyzing powers A(ij), the polarization transfer coefficients K(y('))(ij), and the induced polarization P(y(')) were measured for the dp elastic scattering at 270 MeV. The cross section and A(d)(y) are well reproduced by Faddeev calculations with modern data-equivalent nucleon-nucleon forces plus the Tucson-Melbourne three-nucleon force. In contrast, A(ij), K(y('))(ij), or P(y(')) are not described by such calculations. These facts indicate the deficiencies in the spin dependence of the Tucson-Melbourne force and call for extended three-nucleon force models.

Impairment of B lymphopoiesis in precocious aging (klotho) mice

Inactivation of the klotho gene in mice results in multiple disorders that resemble human aging after 3 weeks of age. Because hematopoiesis, especially B lymphopoiesis, is affected in humans and mice by aging, we analyzed the hematopoietic state in homozygous klotho (kl/kl) mice. The kl/kl mice showed thymic atrophy and a reduced number of splenocytes. These mice had almost the normal number of myeloid cells, erythroid cells, IL-3-responsive myeloid precursors and colony forming units in spleen (CFU-S) in bone marrow (BM), but had a substantially decreased number of B cells in BM and peripheral blood as compared with wild-type mice. IL-7-responsive B cell precursors and all of the maturation stages of B cells in BM were also reduced. However, the function of hematopoietic stem cells including their capacity of B lymphopoiesis in vivo and in vitro was normal. Early B cell development was also normal in neonates and young kl/kl mice until 2 weeks old without aging phenotypes. RT-PCR analysis revealed that the level of IL-7 gene expression was significantly reduced in freshly isolated kl/kl BM cells. However, injection of IL-7 in kl/kl mice could not rescue the B lymphopenia. These findings indicate that Klotho protein may regulate B lymphopoiesis via its influence on the hematopoietic microenvironment.

Emergency abdominal surgery in patients aged 80 years and older

The outcome of emergency abdominal surgery in elderly patients remains unsatisfactory. We studied factors contributing to the outcome of abdominal emergency surgery in elderly patients, particularly in those aged 80 years and older. Subjects were 61 patients aged 80 years and older (group A) and 108 patients aged from 65 to 79 years (group B) who underwent emergency abdominal surgery between 1983 and 1997. Complications were significantly higher in group A than in group B, with respiratory failure the most common postoperative complication. Mortality rate within 30 days after surgery was also higher in group A (9.8%) than in group B (3.3%). Complications and mortality did not differ significantly between those with and without preexisting concomitant disease in group A. Systemic inflammatory response syndrome (SIRS) was seen in 35 patients in group A and 50 in group B. Severe complications occurred in 62.5% of group A with preoperative SIRS. Mortality in those with SIRS was significantly higher than those without. SIRS is thus a feasible predictor of poor outcome in patients aged 80 years and older who have emergency abdominal surgery and in those aged from 65 to 79 years. Patients with SIRS should initially receive minimal treatment whenever possible, rather than be overtreated, until their conditions stabilize.

Hepatitis C virus structural proteins induce liver cell injury in transgenic mice

To develop an animal model of hepatitis C virus (HCV) infection, transgenic mice carrying part of the HCV cDNA (C980) encoding HCV-core and envelope proteins under control of the mouse class I major histocompatibility complex gene (H-2K) regulatory region were produced. HCV-C980 RNA and HCV-core protein were present in livers from line H36 as determined by RNase protection assay and immunostaining, respectively. More than 40 animals from line H36 were examined histologically. Most of these H36 mice after 10 months of age developed spontaneous focal infiltration of lymphocytes, hepatocyte necrosis, degeneration, and altered foci with mitotic hepatocytes. These pathological lesions were absent in livers from the age-matched control littermates. Liver cells from these H36 mice were sensitive to damage induced by intravenous administration of an anti-Fas antibody. It is suggested that HCV-C980 proteins by themselves may be one causative agent of liver cell injury in subjects with HCV infection.

Hepatitis C virus structural proteins induce liver cell injury in transgenic mice

To develop an animal model of hepatitis C virus (HCV) infection, transgenic mice carrying part of the HCV cDNA (C980) encoding HCV-core and envelope proteins under control of the mouse class I major histocompatibility complex gene (H-2K) regulatory region were produced. HCV-C980 RNA and HCV-core protein were present in livers from line H36 as determined by RNase protection assay and immunostaining, respectively. More than 40 animals from line H36 were examined histologically. Most of these H36 mice after 10 months of age developed spontaneous focal infiltration of lymphocytes, hepatocyte necrosis, degeneration, and altered foci with mitotic hepatocytes. These pathological lesions were absent in livers from the age-matched control littermates. Liver cells from these H36 mice were sensitive to damage induced by intravenous administration of an anti-Fas antibody. It is suggested that HCV-C980 proteins by themselves may be one causative agent of liver cell injury in subjects with HCV infection.

[Relationship between renal function and morphometric assessment in chronic glomerulonephritis]

In an attempt to reveal a correlation between the degree of glomerular hypertrophy, interstitial damage, and hemodynamic parameters in chronic nephritis, the glomerular area (GA) and proportion of interstitial area (IA%) were determined quantitatively with an image analyzer, and the effective renal plasma flow (ERPF) and filtration fraction (FF) were determined simultaneously. The subjects were 12 patients with focal glomerulosclerosis (FGS) and 12 patients with IgA nephropathy (IgAN), all of whom had a similar glomerular filtration rate (GFR). The GFR was 58.6 +/- 11.4 ml/min/1.48 m2 in the FGS group and 53.9 +/- 13.1 ml/min/1.48 m2 in the IgAN group, and the difference between the two groups was not significant. On the other hand, ERPF was significantly lower and FF was significantly higher in the FGS group than in the IgAN group. GA was significantly higher in the FGS group than in the control group (10 kidney donors), and GA in the IgAN group was equivalent to that in the control group. IA% was almost equal in the FGS and IgAN groups, and significantly higher in both groups than in the control group. Although GA was not correlated with GFR in the two groups, it tended to be positively correlated with FF in the FGS group, and the correlation between GA and FF reached statistical significance when the IgAN group was combined with the FGS group. The above findings suggest that the pattern of progression of the glomeruli and interstitial lesions and of the intrarenal hemodynamics involved in them may differ in the FGS and IgAN groups. However, since ERPF significantly decreased in the FGS group, even though IA% was the same in both groups, the possibility that ERPF was functionally decreased in the FGS group cannot be ruled out.

An enhancer element for expression of the Ncx (Enx, Hox11L1) gene in neural crest-derived cells

The murine Ncx (Enx, Hox11L1) gene is specifically expressed in a neuronal subset of neural crest-derived tissues. In attempts to elucidate the regulatory DNA element of the tissue-specific expression, we sequenced the 5'-flanking region of the Ncx gene. The transcriptional initiation site was determined at 297 nucleotides (-297) upstream from the ATG start codon (+1). A retinoic acid response element was located on the region between -1163 and -1150. Transient transfection assays with the 5'-flanking sequences fused to the luciferase gene showed that the region between -1387 and -1368 was crucial for the tissue-specific enhancer activity. Furthermore, nuclear proteins extracted from neural crest-derived cells such as murine and human neuroblastoma cells bind to the DNA region between -1387 and -1368. This DNA element was also conserved in the 5'-flanking region of the human NCX gene. Our observations strongly suggest that the DNA element (between -1387 and -1368) contributes to tissue-specific expression of the Ncx gene in murine and human species.

The role of Bcl6 in mature cardiac myocytes

OBJECTIVE

The Bcl6 gene encodes a sequence-specific transcriptional repressor and is ubiquitously expressed in adult murine tissues including heart muscle. The objective of this study was to examine the role of Bcl6 in cardiac myocytes.

METHOD

We developed Bcl6-deficient (Bcl6-/-) mice and histologically examined hearts from these mice.

RESULTS

Massive myocarditis with eosinophilic infiltration occurred in Bcl6-/- mice after 4-6 weeks of age. Since expression of the Bcl6 gene was induced in normal cardiac myocytes after 2 weeks of age and thereafter detected through adulthood, loss of Bcl6 in mature cardiac myocytes may be related to the induction of eosinophilic myocarditis. To examine the effects of eosinophils from Bcl6-/- mice on normal hearts, bone marrow cells from Bcl6-/- mice were adoptively transferred into sublethally irradiated RAG1-deficient mice. Although massive eosinophilic infiltration was detected in conjunctivas and spleens from the chimeric mice, myocarditis was never observed. Electron microscopic analysis of cardiac myocytes from Bcl6-/- mice revealed a spectrum of degenerative changes prior to eosinophilic infiltration.

CONCLUSION

Bcl6 maynot be essential for the maturation of cardiac myocytes but may play a role in protecting mature cardiac myocytes from eosinophilic inflammation.

Enlargement of the globe with ocular malformations in c-Myc transgenic mice

PURPOSE

To study the ocular development in transgenic mice carrying the mouse c-myc gene under the control of the Mx gene promoter (Mx-c-myc).

METHODS

Transgenic mice were generated by standard techniques. For histological studies, the tissues were fixed with 10% buffered formalin, embedded in paraffin according to the standard procedure and sliced in 4-microm sections. c-Myc expression was investigated by reverse transcriptase-polymerase chain reaction and Southern blot analysis.

RESULTS

A line of the Mx-c-myc mice displayed progressive enlargement of the globe with other ocular malformations. Histologically, the enlarged eyes exhibited closed cornea-iris angle, microphakia, corneal epithelial disorders, and attenuation of the inner retinal layers. Developmental analysis of eyes from these Mx-c-myc mice revealed irregular development of the iris and ciliary body at embryonic day 15.5 and the closed angle at 1 week of age. Leaky exogenous c-myc expression was detected in cornea, iris, lens, and retina from the Mx-c-myc mice by reverse transcriptase-polymerase chain reaction and Southern blot analysis. No other developmental abnormalities were observed in the Mx-c-myc mice. The anterior segment of the enlarged eyes showed the closed angle with elongation of the iris and ciliary body. There was no attenuation in the outer retinal layers from the outer plexiform layer to the retinal pigment epithelium.

CONCLUSIONS

We conclude that the buphthalmos and accompanying changes were not due to expression of the exogenous c-myc in cornea and retina but may be the secondary changes of elevated intraocular pressure. We suggest that Mx-c-myc mice can serve as a useful model for investigating the development of the anterior segment and the genesis of buphthalmos.

Expression of a murine homologue of the inhibitor of apoptosis protein is related to cell proliferation

The inhibitor of apoptosis (IAP) proteins form a highly conserved gene family that prevents cell death in response to a variety of stimuli. Herein we describe a newly defined murine IAP, designated Tiap, that proved to be a murine homologue of human survivin based on sequence comparison. TIAP has one baculovirus IAP repeat and lacks a C-terminal RING finger motif. TIAP interacted with the processed form of caspase 3 and inhibited caspase-induced cell death. Histological examinations revealed that TIAP is expressed in growing tissues such as thymus, testis, and intestine of adult mice and many tissues of embryos. In in vitro studies, TIAP was induced in splenic T cells activated with anti-CD3 antibody or Con A, and the expression of TIAP was up-regulated in synchronized NIH 3T3 cells at S to G2/M phase of the cell cycle. We propose that during cell proliferation, cellular protective activity may be augmented with inducible IAPs such as TIAP.

Non-N-methyl-D-aspartate receptors may mediate the transmission of emetic signals between visceral vagal afferents and the solitary nucleus in dogs

The effects of the N-methyl-D-aspartate (NMDA) and non-NMDA receptor antagonists MK-801 and NBQX, respectively, on salivary secretion and retching induced by vagal stimulation were studied in decerebrate dogs. Vagal stimulation induced an increase in salivary secretion and fictive retching. Intra-4th ventricular application of vehicle or MK-801 did not change either response, while NBQX completely abolished both responses. These results suggest that non-NMDA receptors mediate both responses in the solitary nucleus.

Introduction of an osteopontin gene confers the increase in B1 cell population and the production of anti-DNA autoantibodies

Osteopontin (OPN) is an Arg-Gly-Asp-containing phosphoprotein that is secreted by activated T cells. The concentration of serum OPN protein is elevated in autoimmune-prone MRL-lpr mice as well as in patients with systemic lupus erythematosus. Previously, it was shown that OPN induces the polyclonal activation of B cells, resulting in the augmented production of immunoglobulin, indicating that OPN plays some role in the development of autoimmune disease. However, the link between OPN and development of autoimmune disease remains unclear. To analyze the role of OPN in immune system and autoimmune diseases, we have generated two kinds of transgenic mice: one carries the immunoglobulin (Ig) enhancer/SV40 promoter and the other carries the cytomegalovirus enhancer/chicken beta-actin (CAG) promoter. In both groups of transgenic mice, the B1 cell population in peritoneal cavity was markedly increased and titer of IgM and IgG3 antibodies in the serum was considerably higher than that in wild-type mice. Most important, the titer of the IgM class of anti-double-stranded DNA antibody was significantly elevated in transgenic mice. These results strongly suggest that OPN may have an important role in the propagation and differentiation of B1 cells and production of autoantibodies.

A neurokinin-1 receptor antagonist reduced hypersalivation and gastric contractility related to emesis in dogs

The roles of tachykinin neurokinin-1 (NK1) receptors in the induction of fictive retching, hypersalivation, and gastric responses associated with emesis induced by abdominal vagal stimulation were studied in paralyzed, decerebrated dogs. Vagal stimulation induced gradual increases in salivary secretion and activity of the parasympathetic postganglionic fibers to the submandibular gland, relaxation of the gastric corpus and antrum, and fictive retching. However, hypersalivation and increased nerve activity were suppressed and antral contractility was enhanced during fictive retching. An NK1 receptor antagonist, GR-205171, abolished the enhancement of antral contractility and fictive retching but had no effect on corpus and antral relaxation. Hypersalivation and increased nerve activity were inhibited by GR-205171 but were not completely abolished. Reflex salivation by lingual nerve stimulation was unaffected. These results suggest that GR-205171 acts on the afferent pathway in the bulb and diminishes hypersalivation and antral contraction related to emesis as well as fictive retching but does not affect gastric relaxation or hypersalivation induced by the vagovagal, vagosalivary, and linguosalivary reflexes.

c-Fos induces apoptosis in germinal center B cells

We examined the role of c-Fos in the differentiation of mature B cells into IgG-producing cells using transgenic mice carrying the c-fos gene under the control of the IFN-alpha/beta-inducible Mx promoter (Mx-c-fos) or the constitutive H-2Kb promoter (H2-c-fos). Splenic B cells from Mx-c-fos mice were cultured with LPS and rIL-4, and IgG1+ B cells were developed in the culture after day 3. When IFN-alpha/beta was added to the culture from day 2, development of IgG1+ B cells was perturbed, and the number of apoptotic cells increased within 24 h, suggesting that c-Fos induces apoptosis in Ig class-switching B cells. To confirm the effect of c-Fos on B cell differentiation in vivo, H2-c-fos mice were immunized with DNP-OVA. The mice produced primary IgM, but not IgG, anti-DNP Ab in serum and failed to generate germinal centers in spleen. The perturbation of germinal center formation in H2-c-fos mice was rescued by mating them with transgenic mice carrying the bcl-2 gene with the Ig promoter. However, primary IgG1 anti-DNP Ab production was still suppressed in doubly transgenic mice, suggesting that Bcl-2 can delay the time of c-Fos-induced apoptosis in Ig class-switching B cells but cannot rescue the death. Since c-Fos is induced in mature B cells reacted with Ags, and clonal deletion of self-reactive B cells in germinal centers is insensitive to Bcl-2, these results suggest that c-Fos plays a causal role in clonal deletion of germinal center B cells.

Reperfusion induces sublethal endothelial injury

BACKGROUND

Endothelial cells are pivotal in regulating thrombosis and hemostasis. In this study, we sought to characterize endothelial dysfunction and endothelial cell injury in vitro after hypoxia/reoxygenation.

MATERIALS AND METHODS

Cultured human umbilical vein endothelial cells (ECs) were exposed to 120 min of hypoxia followed by reoxygenation. The release of thrombomodulin (TM) and the production of prostaglandin I2 (PGI2) were measured. Endothelial cell injury in hypoxia/reoxygenation was measured by two assays, the Fura-2 release assay and the 51chromium (51Cr) release assay.

RESULTS

TM release from ECs during normoxic incubation was undetectable, while it was slightly increased during hypoxic incubation. After reoxygenation, the release of TM increased, and it became significantly higher at 120 min after reoxygenation compared with hypoxic incubation. The production of PGI2 significantly decreased during hypoxic incubation and further decreased within 30 min after reoxygenation, but returned to normoxic levels at 120 min after reoxygenation. In the Fura-2 release assay, a rapid and significantly greater release of Fura-2 was observed in hypoxia/reoxygenation compared with hypoxic incubation. In the 51Cr release assay which demonstrates cell death, 51Cr release did not increase in hypoxia/reoxygenation.

CONCLUSIONS

The present study suggests that 120 min of hypoxia/reoxygenation induces endothelial dysfunction of ECs but does not cause cell death.

BAZF, a novel Bcl6 homolog, functions as a transcriptional repressor

The BCL6 gene, which has been identified from the chromosomal translocation breakpoint in B-cell lymphomas, functions as a sequence-specific transcriptional repressor. We cloned a novel Bcl6-homologous gene, BAZF (encoding Bcl6-associated zinc finger protein). The predicted amino acid sequence of BAZF indicated that the BTB/POZ domain and the five repeats of the Krüppel-like zinc finger motif are located in the NH2-terminal region and the COOH-terminal region, respectively. BAZF associated with Bcl6 at the BTB/POZ domain and localized in the nucleus. Since zinc finger motifs of BAZF were 94% identical to those of Bcl6 at the amino acid level, BAZF bound specifically to the DNA-binding sequence of Bcl6 and functioned as a transcriptional repressor. The repressor activity was associated with both the BTB/POZ domain and the middle portion of BAZF. The 17-amino-acid sequence in the middle portion was completely conserved between BAZF and Bcl6, and the conserved region was critical for the repressor activity. Expression of BAZF mRNA, like that of Bcl6 mRNA, was induced in activated lymphocytes as an immediate-early gene. Therefore, the biochemical character of BAZF is similar to that of Bcl6 although the tissue expression pattern of BAZF differs from that of Bcl6. This is apparently the first report of a gene family whose members encode zinc finger proteins with the BTB/POZ domain.

An acute experiment on retrograde intestinal peristalsis with emesis using decerebrated dogs

This acute experiment using decerebrated dogs was a new model for studies of central and peripheral mechanisms of intestinal motility with emesis, and was undertaken to clarify the relationship between intestinal contractions and the retrograde transport of intestinal contents with emesis. Contractility of the small intestine was recorded by five force transducers. Reflux of mannitol solution injected into the small intestine through the proximal duodenum was recorded by a magnetic flow meter. Retching was induced by vagal afferent stimulation, intramuscular apomorphine, or intragastric copper sulfate. Intestinal contractility was enhanced preceding retching caused by these emetic stimuli. Characteristic contractions in the oral direction were observed in the small intestine before and during retching. These contractions originated in the caudal or middle intestine and conducted to the duodenum intermittently, rather than continuously. Reflux of mannitol solution to the proximal duodenum was observed just after the initiation of retching, and was sometimes observed repeatedly during retching. These results suggest that intestinal contents are repeatedly transported to the proximal duodenum during retching by intermittent retrograde contractions. Acute experiments using decerebrated dogs seem to be useful and essential for studies of central and peripheral mechanisms of emesis.

Alteration of T-lymphocyte subpopulations in patients with primary renal diseases and systemic lupus erythematosus

Forty-eight patients with a variety of primary renal diseases and systemic lupus erythematosus (SLE) were examined for the proportion of circulating T lymphocytes bearing receptors for IgM (T mu cells) or IgG (T gamma cells). Although the control group showed strikingly similar mean values for both T mu and T gamma cells, the whole group of patients with primary renal diseases and SLE showed a wide scatter of values. Sixteen patients with primary renal diseases and SLE had higher proportions of T gamma cells than the control group, whereas seven patients with chronic glomerulonephritis (CGN), membranoproliferative glomerulonephritis (MPGN), lipoid nephrosis (LN), and SLE showed very marked decrease in the proportions of T gamma cells in the peripheral blood. On the other hand, six out of the total group of patients had low proportions of T mu cells in the peripheral blood. However, no consistent relationship between the proportion of T mu and T gamma cells was found in our study. These findings indicate that there exists a heterogeneity of T-lymphocyte subpopulation distribution in some patients with primary renal diseases and SLE. The possible significance of these phenomena in the pathophysiology of renal diseases is discussed.

A physiologic role of Bcl-xL induced in activated macrophages

Activated macrophages produce nitric oxide (NO) that is an important effector molecule for their antimicrobial and antitumor activities. Since this NO is also toxic for themselves, they have self-defense mechanisms. To elucidate the mechanisms in a physiologic condition, expression of bcl-2 family genes were examined in peritoneal macrophages and RAW264 macrophage cell line activated with IFN-gamma and LPS. Bcl-xL, but not bcl-2 and bax mRNA, was highly inducible within 3 h after stimulation. The induction required new protein synthesis, but was independent of effects of synthesized NO. Since activated RAW264 were more resistant to NO-induced apoptosis mediated by the exposure to S-nitroso-N-acetyl-penicillamine (SNAP) than nonactivated RAW264, the inducible Bcl-xL may play a role in the protection from NO toxicity. To confirm the protective function, RAW264 were stably transfected with bcl-xL. Those transfectants activated with IFN-gamma and LPS appeared highly resistant to NO-induced cell death detected within 24 h after stimulation, although their NO production was similar to those of parental RAW264 and neomycin control-transfected cells. Furthermore, bcl-xL transfectants displayed substantial protection from SNAP-induced apoptosis. These results establish a link between self-defense to the synthesized NO and the induction of Bcl-xL in activated macrophages.

Link between light and fatty acid synthesis: thioredoxin-linked reductive activation of plastidic acetyl-CoA carboxylase

Fatty acid synthesis in chloroplasts is regulated by light. The synthesis of malonyl-CoA, which is catalyzed by acetyl-CoA carboxylase (ACCase) and is the first committed step, is modulated by light/dark. Plants have ACCase in plastids and the cytosol. To determine the possible involvement of a redox cascade in light/dark modulation of ACCase, the effect of DTT, a known reductant of S-S bonds, was examined in vitro for the partially purified ACCase from pea plant. Only the plastidic ACCase was activated by DTT. This enzyme was activated in vitro more efficiently by reduced thioredoxin, which is a transducer of redox potential during illumination, than by DTT alone. Chloroplast thioredoxin-f activated the enzyme more efficiently than thioredoxin-m. The ACCase also was activated by thioredoxin reduced enzymatically with NADPH and NADP-thioredoxin reductase. These findings suggest that the reduction of ACCase is needed for activation of the enzyme, and a redox potential generated by photosynthesis is involved in its activation through thioredoxin as for enzymes of the reductive pentose phosphate cycle. The catalytic activity of ACCase was maximum at pH 8 and 2-5 mM Mg2+, indicating that light-produced changes in stromal pH and Mg2+ concentration modulate ACCase activity. These results suggest that light directly modulates a regulatory site of plastidic prokaryotic form of ACCase via a signal transduction pathway of a redox cascade and indirectly modulates its catalytic activity via stromal pH and Mg2+ concentration. A redox cascade is likely to link between light and fatty acid synthesis, resulting in coordination of fatty acid synthesis with photosynthesis.

A novel pathogenesis of megacolon in Ncx/Hox11L.1 deficient mice

The Ncx/Hox11L.1 gene, a member of the Hox11 homeobox gene family, is mainly expressed in neural crest-derived tissues. To elucidate the role of Ncx/Hox11L.1, the gene has been inactivated in embryonic stem cells by homologous recombination. The homozygous mutant mice were viable. These mice developed megacolon with enteric ganglia by age 3-5 wk. Histochemical analysis of the ganglia revealed that the enteric neurons hyperinnervated in the narrow segment of megacolon. Some of these neuronal cells degenerated and neuronal cell death occurred in later stages. We propose that Ncx/Hox11L.1 is required for maintenance of proper functions of the enteric nervous system. These mutant mice can be used to elucidate a novel pathogenesis for human neuronal intestinal dysplasia.

Disruption of the Bcl6 gene results in an impaired germinal center formation

The Bcl6 gene has been identified from the chromosomal translocation breakpoint in B cell lymphomas, and its products are expressed highly in germinal center (GC) B cells. To investigate the function of Bcl6 in lymphocytes, we have generated RAG1-deficient mice reconstituted with bone marrow cells from Bcl6-deficient mice (Bcl6(-/-)RM). Lymphogenesis in primary lymphoid tissues of Bcl6(-/-)RM is normal, and Bcl6(-/-)RM produced control levels of primary IgG1 antibodies specific to T cell-dependent antigens. However, GCs were not found in these mice. This defect was mainly due to the abnormalities of B cells. Therefore, Bcl6 is essential for the differentiation of GC B cells.

A negative regulatory region of the murine Hox11 gene

The HOX11 gene was isolated from the chromosomal breakpoint of human T cell acute lymphoblastic leukemias with a chromosomal translocation t(10;14). Expression of this proto-oncogene is strictly controlled in normal tissues. However, regulatory elements of the gene have never been studied. Since the HOX11 gene is well conserved between human and murine, we sequenced 5' flanking region of the murine Hox11 gene and analyzed the elements. We identified the transcription start site (+1) of the gene using mRNA from fetal spleens by primer extension analysis. The start site was determined at 795 bp upstream from the ATG site. A typical TATA box sequence was found at 35 bp upstream from the start site. Furthermore, promoter activity of the 5' flanking region of the start site was monitored by luciferase assay. The activity mainly located within a 540-bp fragment immediately upstream from the start site (-540 to +1). The (-1240 to -540) region contained a negative regulatory element of the transcription. The TATA box sequence and the nucleotide sequence around the transcription start site were conserved in the human HOX11 gene. The transcription start site of the human HOX11 gene in normal tissues is discussed.

Ncx, a Hox11 related gene, is expressed in a variety of tissues derived from neural crest cells

We have isolated the murine homeobox gene (Ncx) that belong to a Hox11 gene family. Expression of the Ncx gene was analyzed in total RNAs from embryos by reverse transcribed polymerase chain reaction (RT-PCR). The mRNA was detected in embryos after 9.5 days of embryogenesis (E9.5) and was maximal at E12.5. The RT-PCR also detected the message in total RNAs from adrenal glands and intestine in adult mice. The expression was further examined in various tissues from embryos by in situ hybridization. It was detected in dorsal root ganglia, cranial nerve ganglia (V, IX, X), enteric nerve ganglia and adrenal glands from embryos between E9.5 and E13.5. Since its expression is restricted to tissues derived from neural crest cells, Ncx may play a role in differentiation and proliferation of neural crest lineage cells.

[A limitation of the split-dose method for evaluating rCBF changes using 99mTc-ECD and SPECT]

The purpose of the study is to validate the split-dose method corrected with dose ratio of 99mTc-ECD for brain perfusion scan. A dose of 600 MBq of 99mTc-ECD was divided into two with various dose ratios from 1:1 to 1:4, and injected to eleven patients with various cerebral diseases. A lesser dose of 99mTc-ECD was injected under a control state for the first SPECT scan, and 15 min SPECT scan was performed 10 min after injection with a triple-head high resolution gamma camera. After the scan, the other dose of 99mTc-ECD was injected under the same control state and the second SPECT scan was performed as same as above. A ratio of the activity of the first scan to the net activity of the second scan corrected by dose ratio, defined as K, was measured in brain regions of each subject. Expected value of K was 1, but the value was distributed with large variations in each subject. The mean % error of the K value was 10.4 +/- 4.9%. Hence it is considered that activity changes by more than 20% from the control values should be required to detect a significant rCBF change in an activation SPECT study. Then, we proposed a new method in which the activity of both two SPECT scans was normalized by cerebellar or occipital activity and compared. The ratio obtained by the proposed method came closer to 1 with less variations and with less mean % error in comparison with those of K value obtained by the dose-correction method. Although the proposed method has a limitation in the use of an activation study loaded with Diamox, it may be useful to evaluate an alteration of rCBF in the study such as postural testing or finger-moving test.

[A comparative study of the quality of SPECT images obtained by 123I-IMP, 99mTc-HMPAO and 99mTc-ECD]

The purpose of this study was to comparatively evaluate the quality of SPECT images for the mapping of rCBF using three tracers, 123I-IMP, 99mTc-HMPAO and 99mTc-ECD. We performed three SPECT studies on seven patients with various cerebral diseases under the same conditions. An effect of Lassen's correction on SPECT images obtained by HMPAO was also evaluated. The same irregular regions of interest were placed on the four transaxial SPECT images. To quantitatively evaluate the pattern of tracer uptake and image contrast, the uptake ratio, regional count/mean count of the cerebrum, and its coefficient variations (CV) were defined, respectively. The order of the value of CV was HMPAO with correction > IMP > ECD > HMPAO without correction. HMPAO with correction showed the best image contrast, but HMPAO without correction was the worst. Uptake ratios of ECD and HMPAO with correction were decreased in the brain stem and thalamus in comparison with those of IMP. Both uptake ratios of ECD and HMPAO without correction were increased in the occipital cortex. IMP provides high quality SPECT images. Images obtained by HMPAO should be modified by Lassen's correction to increase image contrast. ECD or HMPAO should not be used to evaluate patients with spinocerebellar degeneration.

Overexpression of c-fos inhibits down-regulation of a cyclin-dependent kinase-2 inhibitor p27Kip1 in splenic B cells activated by surface Ig cross-linking

Splenic B cells activated by surface Ig (sIg) cross-linking transiently express the c-fos gene within 0.5 h and then enter into S phase of the cell cycle within 48 h. To investigate a role of c-fos in cell cycle progression, we used splenic B cells from IFN-alphabeta-inducible c-fos transgenic mice (Mx-c-fos). In the absence of IFN, the cell cycle progression of Mx-c-fos B cells stimulated with anti-IgM Ab was similar to that in control B cells. The cell cycle was arrested in G1 phase when we added IFN to the culture within 12 h after anti-IgM Ab stimulation, suggesting that overexpression of c-fos until mid-G1 phase perturbs activation of the cell cycle regulatory machinery. In control B cells, cyclin E and cdk2 were induced within 24 to 48 h after stimulation, and this induction was accompanied by down-regulation of a cdk2 inhibitor p27Kip1. As a consequence of these activation processes, cdk2 kinase activity was induced in B cells in the late G1 phase. However, kinase activity was not detected in Mx-c-fos B cells, presumably because the down-regulation of p27 was perturbed. These data suggest that c-Fos can negatively control cell cycle regulatory machinery in sIg-stimulated B cells.

Overexpression of c-fos inhibits down-regulation of a cyclin-dependent kinase-2 inhibitor p27Kip1 in splenic B cells activated by surface Ig cross-linking

Splenic B cells activated by surface Ig (sIg) cross-linking transiently express the c-fos gene within 0.5 h and then enter into S phase of the cell cycle within 48 h. To investigate a role of c-fos in cell cycle progression, we used splenic B cells from IFN-alphabeta-inducible c-fos transgenic mice (Mx-c-fos). In the absence of IFN, the cell cycle progression of Mx-c-fos B cells stimulated with anti-IgM Ab was similar to that in control B cells. The cell cycle was arrested in G1 phase when we added IFN to the culture within 12 h after anti-IgM Ab stimulation, suggesting that overexpression of c-fos until mid-G1 phase perturbs activation of the cell cycle regulatory machinery. In control B cells, cyclin E and cdk2 were induced within 24 to 48 h after stimulation, and this induction was accompanied by down-regulation of a cdk2 inhibitor p27Kip1. As a consequence of these activation processes, cdk2 kinase activity was induced in B cells in the late G1 phase. However, kinase activity was not detected in Mx-c-fos B cells, presumably because the down-regulation of p27 was perturbed. These data suggest that c-Fos can negatively control cell cycle regulatory machinery in sIg-stimulated B cells.

Overexpression of c-Fos induces apoptosis of CD43+ pro-B cells

The proto-oncogene product c-Fos, a component of the transcription factor AP-1, is induced in early B lineage cells. To investigate a role of c-Fos in early B cell development, fetal liver (FL) cells from transgenic mice carrying an IFN-alphabeta (IFN)-inducible c-fos gene (Mx-c-fosD) were cultured on a stromal cell layer with IL-7. Although B lineage cells normally developed in the Mx-c-fosD FL cell culture, the development was perturbed by the addition of IFN at the beginning of culture. When IFN was added in the FL culture after B lineage cells developed, pro-B (B220+,CD43+) cells were selectively dying by apoptosis within 48 h after IFN stimulation. This apoptosis was intrinsically induced in the pro-B cells that overexpressed c-fos when the Mx-c-fosD FL (H-2Kb) cells were cocultured with the normal C3H FL (H-2Kk) cells. The molecular basis of the apoptosis was investigated by examining expression of the genes that regulate apoptosis. The IFN stimulation did not modulate expression of Bcl-2 and Fas in early B lineage cells from the Mx-c-fosD FL culture. However, Rag-2 was down-regulated in these cells within 12 h after IFN stimulation. These results suggest that the c-Fos plays a causal role in deletion of pro-B cells with nonfunctional Ag receptor.

Overexpression of c-Fos induces apoptosis of CD43+ pro-B cells

The proto-oncogene product c-Fos, a component of the transcription factor AP-1, is induced in early B lineage cells. To investigate a role of c-Fos in early B cell development, fetal liver (FL) cells from transgenic mice carrying an IFN-alphabeta (IFN)-inducible c-fos gene (Mx-c-fosD) were cultured on a stromal cell layer with IL-7. Although B lineage cells normally developed in the Mx-c-fosD FL cell culture, the development was perturbed by the addition of IFN at the beginning of culture. When IFN was added in the FL culture after B lineage cells developed, pro-B (B220+,CD43+) cells were selectively dying by apoptosis within 48 h after IFN stimulation. This apoptosis was intrinsically induced in the pro-B cells that overexpressed c-fos when the Mx-c-fosD FL (H-2Kb) cells were cocultured with the normal C3H FL (H-2Kk) cells. The molecular basis of the apoptosis was investigated by examining expression of the genes that regulate apoptosis. The IFN stimulation did not modulate expression of Bcl-2 and Fas in early B lineage cells from the Mx-c-fosD FL culture. However, Rag-2 was down-regulated in these cells within 12 h after IFN stimulation. These results suggest that the c-Fos plays a causal role in deletion of pro-B cells with nonfunctional Ag receptor.

The BCL6 gene is predominantly expressed in keratinocytes at their terminal differentiation stage

We analyzed the expression of the BCL6 gene in mouse tissues by in situ hybridization. The expression was strong in the upper layer but undetectable in the basal layer of epidermis from adult mice. When human keratinocytes were cultured with a high concentration of calcium ion, these cells stopped their proliferation and differentiated to their terminal stage. In these keratinocytes, BCL6 expression was induced after stimulation and progressively up-regulated. The kinetics was very similar to that of a cyclin dependent kinase inhibitor p21sdil/cip1/WAF1 in these cells. These results suggest that BCL6 plays a role in keratinocytes at terminal differentiation stage.

[A functional diagnostic method by measuring of distribution volume of 123I-IMP with SPECT]

To measure distribution volume of 123I-IMP with one-point sampling of arterial blood and 2 times SPECT scans using the Magic square method (Rate constant square method), we introduced a program on a SPECT computer system. In this program four functional images; distribution volume, CBF (K1), k2 and delayed/early ratio, and absolute values with S.D. are obtained on the computer. We have been using the program on daily SPECT studies. In this study we discussed the usefulness of the method. Redistribution phenomenon of 123I-IMP, which is not exactly enough investigated, can be transformed into a functional parameter, distribution volume. Since distribution volume represents an extent of retention of 123I-IMP in brain tissue, it can play an important role to evaluate functional activity in the brain and to diagnose cerebral diseases.

[Validation study in quantitative measurement of regional cerebral blood flow using N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) and SPECT]

We validated following five methods to quantitate regional cerebral blood flow (rCBF) using 123I-IMP and SPECT; 1) microsphere method, which is based on a microsphere model using the SPECT image at five minutes after 123I-IMP injection with continuous withdrawal of arterial blood, 2) microsphere+ one-point sampling method, which is the same as the microsphere method except for using one-point sampling instead of continuous withdrawal, 3) conventional microsphere + one-point sampling method, which is the same as the microsphere + one-point sampling method except for using a later SPECT image corrected with the ratio of alteration of measured entire brain activity, 4) Table look-up method, which is based on a two-compartment model (influx; K1 and outflux; k2) using one arterial blood sample taken at 10 min and two SPECT images at 30 min and 180 min post-injection, and 5) functional IMP SPECT, which is based on the two-compartment model using one arterial blood sample taken at 5 min and two SPECT images at 30 min and 60 min post-injection. Those methods were applied to six patients with cerebral infarction and degenerative diseases, and rCBF results were compared with those estimated by non-linear least squares fitting (NLLSF) analysis based on the two-compartment model. The rCBF values obtained by the microsphere method was best correlated with those by NLLSF analysis (r = 0.940), followed by the microsphere+one-point sampling method (r = 0.885) and the functional IMP SPECT (r = 0.882). The table look-up method underestimated rCBF especially at the high flow level, however showed good correlation (r = 0.859). The conventional microsphere + one-point sampling method overestimated rCBF, however showed good correlation (r = 0.849). Distribution volume (Vd = K1/k2) was also estimated by both the table look-up method and the functional IMP SPECT. While values of Vd by the functional IMP SPECT were significantly correlated with those by NLLSF analysis (r = 0.785), the table look-up method overestimated Vd (43.4 +/- 6.6 ml/g) and showed not good correlation (r = 0.287).

Digalactosyldiacylglycerol suppression of inhibition by sulfoquinovosyldiacylglycerol of alpha-glucosidase

Digalactosyldiacylglycerol (DGDG) suppressed the inhibition by sulfoquinovosyldiacylglycerol (SQDG) of an alpha-glucosidase reaction. Suppressing was considered to be an apparent decrease in inhibitory activity of SQDG ascribed to direct interaction between SQDG and DGDG. This suppression was presumed to be caused by less access of SQDG to the enzyme because SQDG and DGDG formed mixed micelles.

[A new method for measurement of both regional cerebral blood flow and distribution volume using N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) and SPECT]

We developed a new method (functional IMP SPECT) to quantitate both regional cerebral blood flow (rCBF) and distribution volume (Vd) using 123I-IMP and SPECT based on a 2- compartment model (influx; K1 =rCBF and outflux; k2). This method requires one arterial blood sampling at 5 min after injection of the tracer and two SPECT scans at 30 min and 60 min. It takes approximately 60 min for total measurements. The integration of arterial input function is estimated by one blood sample taken at 5 min after injection of the tracer without octanol treatment, by using the correlation between one blood sample and the integration, which was obtained from studies on 25 subjects. With the value of integration, K1 and Vd are calculated from the data of two SPECT scans by using the mathematical functions based on the 2-compartment model, which were obtained from studies on 12 subjects. In the practical range of K1 (0.3-0.7 ml/g/min) and Vd (15-35 ml/g) given in the 2-compartment model, statistical errors of K1 and Vd obtained by the functional IMP SPECT were evaluated at approximately 14.0% and 17.2%, respectively. In clinical studies for eight subjects including two healthy volunteers, three patients with cerebral infarction and three patients with degenerative disease, K1 and Vd values estimated by the functional IMP SPECT were significantly correlated with those estimated by non-linear least squares fitting analysis based on the 2-compartment model, and the mean errors of K1 and Vd estimated by the functional IMP SPECT were approximately 8.0% and 11.2% respectively, suggesting the validity of the new method. We conclude that the functional IMP SPECT is clinically useful because of the accuracy, less-invasiveness and convenience.

[A study on accuracy of rCBF measurements using the conventional microsphere method with N-isopropyl-p-[123I]iodoamphetamine and SPECT]

To evaluate the accuracy of conventional microsphere method for the measurement of regional cerebral blood flow (rCBF) based on the microsphere model with N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) and SPECT, we performed simulation analysis and clinical studies. Although the microsphere method requires early SPECT scan at a few minutes after injection of the tracer for the accurate measurement of rCBF, the conventional microsphere method, which is generally used, requires more delayed SPECT scan with long scan-duration. In the conventional microsphere method, the delayed SPECT image is corrected to the image at a few minutes after injection of the tracer by using the monitored entire brain activity. By the simulation analysis based on the 2-compartment model (influx; K1 and outflux; k2) using the input function and the entire brain activity obtained from eight subjects respectively, it was found that the conventional microsphere method overestimated the rCBF in the practical range of rCBF and Vd (= K1/k2) given in the 2-compartment model. When the values of rCBF and Vd in the 2-compartment model were given at 0.5 (ml/g/min) and 30 (ml/g) respectively, the rate of overestimation of rCBF by the conventional microsphere method was determined to be 17.3 +/- 0.7% (mean +/- S.D.). Also in clinical studies for eight subjects, the conventional microsphere method overestimated the rCBF compared with those evaluated by non-linear least squares fitting (NLLSF) analysis based on the 2-compartment model. Those results agreed well with the simulation analysis, suggesting the validity of the simulation. The rCBF values clinically estimated by the conventional method were, however, significantly correlated with those calculated by NLLSF analysis, and there were not so much difference between the two quantitative rCBF images obtained by the conventional microsphere method and the microsphere method. Therefore, we conclude that the conventional microsphere method is clinically useful in spite of the overestimation of rCBF.

Two forms of Hox11 a T cell leukemia oncogene, are expressed in fetal spleen but not in primary lymphocytes

HOX11 is identified from the breakpoint of human T cell acute lymphoblastic leukemias with t(10;14). Since overexpression of HOX11 in T cells caused leukemias in transgenic mice, the endogenous HOX11 may play a role in proliferation and differentiation of T cells. In order to elucidate the role, we examined the expression of Hox11 in normal lymphocytes by a reverse transcriptase-polymerase chain reaction analysis. Two alternatively spliced Hox11 mRNAs were expressed in fetal spleens. However, lymphocytes did not express Hox11 mRNA during differentiation. Furthermore, it was not induced in primary lymphocytes after activation. These results suggest that ectopic expression of HOX11 in T cells is responsible for leukemogenesis.