A big gene linked to small eyes encodes multiple Mitf isoforms: many promoters make light work

Among more than 80 different loci related to mouse coat color, microphthalmia-associated transcription factor (Mitf) encoded at the mouse microphthalmia locus is one of the most exciting molecules that regulates the development and survival of many cell types, including melanocyte, retinal pigment epithelium (RPE), and mast cells. Mitf and its human homolog MITF consist of at least three isoforms, referred to as Mitf-A/MITF-A, the heart-type Mitf-H/MITF-H, and the melanocyte lineage-specific Mitf-M/MITF-M, respectively. These isoforms differ in the amino-terminal domains but share a transactivation domain and a basic helix-loop-helix and leucine-zipper structure that is required for DNA binding and dimerization. MITF-M is exclusively expressed in melanocytes and melanoma cells, but not in other cell types, including RPE cells. In contrast, MITF-A mRNA is widely expressed in many cell types. These three isoform mRNAs are possibly generated by differential usage of the gene promoters and by alternative splicing. We predict that the entire MITF gene spans about 200 kb of DNA. Like MITF-M, MITF-A is able to activate the two melanogenesis gene promoters, tyrosinase and tyrosinase-related protein 1. These results suggest that melanogenesis may be regulated by different MITF isoforms in melanocyte and RPE. Possible implications of the multiplicity in Mitf/MITF isoforms are discussed.

Targeted disruption of ATF4 discloses its essential role in the formation of eye lens fibres

BACKGROUND

Activating transcription factor-4 (ATF4)--also termed CREB2, C/ATF, and TAXREB67--is a basic-leucine zipper (bZip) transcription factor that belongs to the ATF/CREB family. In addition to its own family members, ATF4 can also form heterodimers with other related but distinct bZIP proteins such as the C/EBP, AP-1 and Maf families, which may give rise to a variety of combinatorial diversity in gene regulation. In order to assess the in vivo essential role of ATF4, we have generated mice lacking ATF4 by gene targeting.

RESULTS

ATF4-deficient mice exhibited severe microphthalmia. Although ATF4-deficient eyes revealed a normal gross lens structure up to embryonic day 14.5, later on the ATF4-deficient lens, degenerated due to apoptosis without the formation of lens secondary fibre cells. Retinal development was normal in the mutant mice. The lens-specific expression of ATF4 in the mutant mice led not only to the recovery of lens secondary fibres but also to the induction of hyperplasia of these fibres.

CONCLUSION

These results demonstrated that ATF4 is essential for the later stages of lens fibre cell differentiation.

Dynamic contrast-enhanced MR imaging of the entire breast with spectral-selective inversion fast three dimensional sequence

Dynamic contrast-enhanced images with high spatial and temporal resolutions were acquired with a fast 3D spoiled gradient echo (SPGR) sequence using spectral selective inversion recovery (IR) pulse. Five healthy volunteers and 12 patients with 14 pathologically proven breast lesions were studied. Fat suppressed volume image data covering the entire breast were obtained with a sufficient spatial resolution (0.9 x 1.5 x 3.0 mm3) and an imaging time of 57 s. By using the criteria including peripheral enhancement and presence of spiculation, sensitivity, specificity, and accuracy in detecting malignant lesions were 88.9, 80.0 and 85.7%, respectively. Although the C/N and S/N ratios were approximately 30% less than those of the conventional fat suppressed 3D technique, fast 3D SPGR imaging with spectral IR method demonstrated sufficient image quality for both time intensity analysis and morphological evaluation of the breast lesions with a data acquisition time less than half of the conventional method. This technique can substantially improve spatial and temporal resolutions of dynamic MR images of the breast and will be useful in evaluating malignant and benign breast lesions.

Cloning of a thermostable ascorbate oxidase gene from Acremonium sp. HI-25 and modification of the azide sensitivity of the enzyme by site-directed mutagenesis

A gene encoding a thermostable ascorbate oxidase (ASOM) was cloned from Acremonium sp. HI-25 and sequenced. The gene comprised 1709 bp and was interrupted by a single intron of 57 bp. ASOM consisted of 551 amino acids including a signal peptide with a molecular mass of 61200, and contained four histidine-rich regions with high sequence homology to the corresponding regions of other multicopper oxidases. The ASOM gene was expressed in Aspergillus nidulans under the Aspergillus oryzae Taka-amylase A gene promoter. The recombinant enzyme (An-ASOM) exhibited almost the same enzymatic properties as ASOM. The ASOM gene was mutated by site-directed mutagenesis with reference to the amino acid sequences of plant enzymes to generate enzymes with altered azide sensitivity. Site-directed mutagenesis at the trinuclear active copper site resulted in an increase in azide resistance; the Ala465Leu and Phe463Trp/Ala465Leu mutants exhibited approximately 10 and 20% increases in azide resistance, respectively.

Defective IL-2-mediated IL-2 receptor alpha chain expression in Stat3-deficient T lymphocytes

Stat3, a member of signal transducers and activators of transcription (STAT), is activated by a variety of cytokines. Recently, mice lacking Stat3 specifically in T cells have been generated and shown to be defective in IL-6-induced proliferation due to the impairment in IL-6-mediated prevention of apoptosis. In the present study, we show that Stat3-deficient T cells are partially defective in IL-2-induced proliferation. Stat3-deficient T cells show impaired IL-2-mediated IL-2 receptor (IL-2R) alpha chain expression. When Stat3-deficient T cells are stimulated with high-dose IL-2, these T cells express IL-2Ralpha and proliferate to similar extents as wild-type T cells. These demonstrate that Stat3 activation is required for efficient T cell proliferation by IL-2 through IL-2Ralpha induction. Taken together, these findings demonstrate that Stat3 activation in T cells is responsible for IL-2- and IL-6-induced proliferation through distinct mechanisms.

Increased expression of connective tissue growth factor in the infarct zone of experimentally induced myocardial infarction in rats

Connective tissue growth factor (CTGF), a 36- to 38-kDa peptide, is selectively induced by transforming growth factor-beta and has been suggested to contribute to tissue repair. To test the hypothesis that CTGF is expressed in myocardial infarct tissue following acute myocardial infarction (AMI), we examined CTGF expression after AMI was experimentally induced in rats. Myocardial infarction was induced by left coronary artery ligation in male Sprague-Dawley rats. Northern blotting demonstrated that the CTGF mRNA expression on days 2, 7 and 14 was increased by 6-, 23- and 8-fold, respectively, compared to that in the pre-ligation hearts. In situ hybridization revealed CTGF mRNA signals on day 2 in myocytes in the infarct marginal zone and spindle-shaped mesenchymal cells (presumably myofibroblasts and fibroblasts) located between surviving myocytes in the infarct peripheral zone. On day 7, the signals were observed in the inner lesion of the infarct around infarct granulation tissue. Western blotting demonstrated that the CTGF protein expression on days 2, 7 and 14 was increased compared to the pre-ligation hearts. Immunopositive staining for CTGF was observed in the inner lesion of the infarct tissue on day 7. In conclusion, the findings demonstrated the increased expression of CTGF in the infarct tissue. Myocytes in the infarct marginal zone and spindle-shaped mesenchymal cells (presumably myofibroblasts and fibroblasts) were the cells responsible for CTGF production.

Stat3 activation is responsible for IL-6-dependent T cell proliferation through preventing apoptosis: generation and characterization of T cell-specific Stat3-deficient mice

Stat3, a member of STAT, is activated by a variety of cytokines such as IL-6 family of cytokines, granulocyte CSF, epidermal growth factor, and leptin. A recent study with mice genetically deficient in the Stat3 gene has revealed its important role in the early embryogenesis. To assess the function of Stat3 in adult tissues, we disrupted the Stat3 gene specifically in T cells by conditional gene targeting using Cre-loxP system. In Stat3-deficient T cells, IL-6-induced proliferation was severely impaired. IL-6 did not enhance cell cycle progression, but prevented apoptosis of normal T cells. In contrast, IL-6 did not prevent apoptosis of Stat3-deficient T cells. Antiapoptotic protein, Bcl-2, was normally up-regulated in response to IL-6 even in Stat3-deficient T cells. These results demonstrate that Stat3 activation is involved in IL-6-dependent T cell proliferation through prevention of apoptosis independently of Bcl-2.

Two cases of myelodysplastic syndrome with extramedullary polyclonal plasma cell proliferation and autoantibody production: possible role of soluble Fas antigen for production of excessive self-reactive B cells

Two cases of myelodysplastic syndrome (MDS) with extramedullary polyclonal plasma cell proliferation and autoantibody production are reported. These cases, which showed leukemic change of refractory anemia with excess of blast (RAEB), developed lymph node swelling and muscle abscess; both were infiltrated mainly with plasma cells, without preceding infection. The proliferation of plasma cells was polyclonal and was proven by negative rearrangement of immunoglobulin heavy chain gene or polyclonal staining of immunoglobulin light chains. These patients showed polyclonal gammopathy and autoantibody production such as positive antinuclear factor and direct antiglobulin test. As was observed in one of the present cases, and as we reported previously, the elevated level of soluble Fas antigen in MDS patients, and its inhibition of apoptotic signaling may be responsible for the excessive accumulation of self-reactive B cells, resulting in these clinical manifestations.

Anomalous insertion of the superior or the inferior vena cava into the right atrium

Three cases with anomalous insertion of the superior or inferior vena cava into the right atrium are presented. One case was a 25-year-old healthy man with anomalous low insertion of the right superior vena cava into the right atrium. The remaining two cases were infants with complex cardiac anomalies showing anomalous high insertion of the inferior vena cava into the right atrium. The congenital anomalies of the connection between the superior and the inferior vena cava and the right atrium are rare. Angiographic and computed tomographic findings of these anomalies were reported.

Pre- and post-synaptic muscarinic receptors in thin slices of rat adrenal gland

The effects of activation of muscarinic receptors on chromaffin cells and splanchnic nerve terminals were studied in a rat adrenal slice preparation. In chromaffin cells, muscarine induced a transient hyperpolarization followed by a depolarization associated with cell spiking. The hyperpolarization was blocked by charybdotoxin (1 microM) and tetraethylammonium chloride (TEA, 1 mM), but was not affected by 200 microM Cd2+ or removal of external Ca2+, consistent with activation of BK channels. This would follow internal Ca2+ mobilization, as shown by Ca2+ imaging with fura-2 on isolated chromaffin cells in culture. Under voltage-clamp, outward BK currents were insensitive to MT3 toxin, a specific muscarinic m4 receptor antagonist. In contrast, muscarine-induced depolarization was due to a m4 receptor-mediated inward current blocked by MT3 toxin. This current was permeable to cations and was associated with Ca2+ entry and subsequently, Ca2+-induced Ca2+ release. Finally, both muscarine (25 microM) and oxotremorine (10 microM) decreased the amplitude and frequency of KCI-evoked excitatory postsynaptic currents, without affecting quantal size, consistent with a presynaptic inhibitory effect. Taken together, our data suggest that activation of m4 and probably m3 muscarinic receptors results in a strong, long-lasting excitation of chromaffin cells, as well as an uncoupling of synaptic inputs onto these cells.

Vasoactive intestinal peptide potentiates and directly stimulates catecholamine secretion from rat adrenal chromaffin cells

The actions of vasoactive intestinal polypeptide (VIP) on catecholamine secretion and changes in [Ca2+]i in single rat chromaffin cells were studied using amperometry and Indo-1. Application of VIP prior to acetylcholine (ACh) or co-application of VIP and ACh enhanced secretion by 94% and 153% respectively, compared to ACh alone. [Ca2+]i was increased by 17% when VIP was preapplied and by 73% upon co-application. Exposure to VIP before stimulation with 60 mM K+ enhanced secretion by 68%, but not [Ca2+]i. VIP application prior to DMPP and nicotine had no effect on [Ca2+]i, but increased [Ca2+]i signals to muscarine by 18%. VIP co-application potentiated only [Ca2+]i responses to muscarine, by 28%. The effect of VIP on muscarine-induced [Ca2+]i signals was mimicked by 8-Br-cAMP, and both were blocked by H-89, a protein kinase A inhibitor. Long-lasting increases in secretion accompanied by a sustained rise in [Ca2+]i to VIP alone were seen in 55% of cells. Removal of Ca2+ or addition of La3+ inhibited both responses, while L-, N- and P-type Ca2+ channel blockers were ineffective. SK&F 96365 inhibited VIP-induced secretion completely and rises in [Ca2+]i by 75%. Neither 8-Br-cAMP nor 8-Br-cGMP evoked responses similar to VIP alone. Thus in rat chromaffin cells, VIP acts both directly as a neurotransmitter in provoking sustained catecholamine secretion in a cAMP-independent manner, and also by enhancing ACh-induced secretion, via a cAMP-dependent action involving muscarinic receptors.

A novel three-dimensional crystal of bacteriorhodopsin obtained by successive fusion of the vesicular assemblies

When the two-dimensional crystal of bacteriorhodopsin (bR), purple membrane, is incubated at high temperature (32 degreesC) with a small amount of the neutral detergent octylthioglucoside in the presence of the precipitant ammonium sulfate, a large fraction of the membrane fragments is converted into spherical vesicles with a diameter of 50 nm, which are able to assemble into optically isotropic hexagonal crystals when the precipitant concentration is increased. The vesicularization of purple membrane takes place under such a condition that the miscibility of the detergent to the aqueous phase becomes very low, and we suggest that it is initiated by insertion of the detergent molecules into the membrane. At low temperature, the transformation into the vesicular structure is inhibited and no large crystal is produced directly from membrane/detergent/precipitant mixtures. When a suspension of the spherical vesicles produced at the high temperature is cooled and concentrated below 15 degreesC, however, a birefringent hexagonal crystal is produced that diffracts X-rays beyond 2.5 A resolution. This new crystal belongs to the space group P622 with unit cell dimensions of a=b=104.7 A and c=114.1 A, and it is shown to be made up of stacked planar membranes, in each of which the bR trimers are arranged on a honeycomb lattice and the space among the proteins is filled with the detergent molecules and native lipids. These stacked membranes are suggested to be produced by successive fusion of the spherical vesicles. This implies that the crystallization is achieved without any step for complete solubilization of the protein. The present result offers a unique crystallization method that may be applicable to such membrane proteins that are liable to denature in the presence of an excess amount of detergent.

Expression of Id1 results in apoptosis of cardiac myocytes through a redox-dependent mechanism

We have constructed a recombinant adenovirus (Ad.Id1) that allows for efficient expression of the helix-loop-helix protein Id1. After infection with Ad.Id1, neonatal cardiac myocytes display a significant reduction in viability, which was proportional to the level of Id1 expression. A similar effect was observed in adult myocytes. Morphological and biochemical assays demonstrated that Id1 expression resulted in myocyte apoptosis. In contrast, expression of Id1 in endothelial cells, vascular smooth muscle cells, or fibroblasts did not affect the viability of these cells. Along with the induction of apoptosis, the expression of Id1 in neonatal cardiac myocytes resulted in an increase in the level of intracellular reactive oxygen species. The source of these reactive oxygen species appears to be the mitochondria. Reducing the ambient oxygen concentration or treatment with a cell-permeant H2O2 scavenger prevented Id1-stimulated apoptosis in cardiac myocytes. These results suggest that the expression of Id1 leads to the induction of apoptosis in cardiac myocytes through a redox-dependent mechanism.

Characterization of neuronal damage by iomazenil binding and cerebral blood flow in an ischemic rat model

I-123-iomazenil is a SPECT probe for central benzodiazepine receptors (BZR) which may reflect intact cortical neuron density after ischemic insults. We evaluated whether neuronal damage in rats could be characterized by iomazenil as compared with cerebral blood flow (CBF). Serial changes in I-125-iomazenil for BZR and I-123-IMP for CBF were analyzed after the unilateral middle cerebral artery occlusion in rats by using an in vivo dualtracer technique. Uptake ratios of affected to contralateral regions were calculated. The iomazenil as well as IMP were decreased in all regions except for the cerebellum (remote area). Both iomazenil and IMP increased over time except in the temporal region (ischemic core). The iomazenil uptake was higher than IMP except in the ischemic core between 1 and 3-4 wk when iomazenil was lower than IMP. Iomazenil showed a moderate decrease in the proximal and middle parietal regions (peri-infarct areas) at 3-4 wk. The triphenyl-tetrazolium-chloride (TTC) stain at 1 wk demonstrated unstained tissue in the temporal region indicating tissue necrosis. With hematoxylin-eosin (HE) stain at 1 wk, widespread neuronal necrosis with occasional intact neurons were found in the proximal parietal region, and isolated necrotic neurons were represented in the distal parietal region. Iomazenil correlated well with the neuron distribution and the finding of a discrepancy between iomazenil and IMP might be useful in evaluating the neuronal damage.

[A case of Foix-Chavany-Marie syndrome and crossed aphasia after right corona radiata infarction with history of left hemispheric infarction]

Foix-Chavany-Marie syndrome (FCMS) is a syndrome that presents facio-pharyngo-glosso-masticatory diplegia with automatic voluntary dissociation. Its most common etiology is stroke in the regions of bilateral opercula. We described a 75-year-old woman with FCMS and crossed aphasia. She had cerebral infarction of left middle cerebral artery territory 23 years before. At that time she had transient right hemiparesis, but no aphasia. This time, she suddenly became mute and was brought to our hospital. Neurological examination revealed severe weakness in her bilateral lower face, pharynx, tongue, and sternocleidomastoideus. She had no weakness of limbs. Her listening comprehension was moderately disturbed and handwriting was paragraphic. Her emotional facial movement was maintained despite of disturbed volitional facial movement. CT scan disclosed fresh infarction at the right corona radiata and old infarction at the left middle cerebral artery territory. In this patient, lesions at the left operculum and right corona radiata with the preserved right operculum gave rise to FCMS. This implies following possibilities: 1) the corticobulbar tract and corticospinal tract run separately at the corona radiata, 2) volitional and emotional tracts of facial movement run separately at the corona radiata. It was demonstrated that FCMS is not always caused by bilateral operculum lesions. Our patient did not show aphasia after the first stroke including left language area, but became severely aphasic after the right corona radiata infarction. Simultaneous occurrence of FCMS and aphasia after corona radiata lesion suggested that the corticobulbar tract and a tract that conducts linguistic information are running adjacently in the corona radiata. Our case suggested that restricted corona radiata lesion may cause severe subcortical aphasia and in case of additional contralateral corticobulbar tract lesion, severe dysarthria may occur.

Characterization, chromosomal localization, and genetic variation of the alpha subunit of porcine eighth component of complement

The complete amino acid sequence of the porcine alpha subunit of the eighth component of complement (C8A) was determined by characterizing the full length cDNA clone isolated from a porcine liver cDNA library. Porcine C8A was found to be similar to human and rabbit C8A in length, leader sequence, conserved cysteine residues, cysteine-rich modules, and overall sequence. Differences in the amino acid sequence among the three species were detected in the proposed candidate site for CD59 recognition (amino acids 352-389). The porcine C8A gene was physically mapped to chromosome 6q33-35 by in situ hybridization using the porcine bacterial artificial chromosome (BAC) clone as a hybridization probe. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of C8A was performed using the restriction enzyme Hha I. Distribution of the alleles was determined in pigs (n = 173) of several different breeds. Estimates of allele frequency of the 201 bp fragment were 0.22,.0.43,.0.04,.0.50,.0.58,.0.50,.0.98, and 0.91 in Landrace, Large White, Duroc, Berkshire, Jinhua, Crown Miniature Pig, wild boar, and Meishan, respectively.

IL-12 up-regulates IL-18 receptor expression on T cells, Th1 cells, and B cells: synergism with IL-18 for IFN-gamma production

IL-18 is a product of macrophages and with IL-12 strikingly induces IFN-gamma production from T, B, and NK cells. Furthermore, IL-18 and 1L-12 synergize for IFN-gamma production from Th1 cells, although this combination fails to affect Th2 cells. In this study, we show that IL-12 and IL-18 promptly and synergistically induce T and B cells to develop into IFN-gamma-producing cells without engaging their Ag receptors. We also studied the mechanism underlying differences in IL-18 responsiveness between Th1 and Th2 cells. Pretreatment of T or B cells with IL-12 rendered them responsive to IL-18, which induces cell proliferation and IFN-gamma production. These IL-12-stimulated cells had both high and low affinity IL-18R and an increased IL-18R mRNA expression. In particular, IL-12-stimulated T cells strongly and continuously expressed IL-18R mRNA. However, when T cells developed into Th1 cells after stimulation with anti-CD3 and IL-12, they lowered this IL-12-induced-IL-18R mRNA expression. Then, such T cells showed a dominant response to anti-CD3 by IFN-gamma production when they were subsequently stimulated with anti-CD3 and IL-18. In contrast, Th2 cells did not express IL-18R mRNA and failed to produce IFN-gamma in response to anti-CD3 and IL-18, although they produced a substantial amount of IFN-gamma in response to anti-CD3 and IL-12. However, when Th1 and Th2 cells were stimulated with anti-CD3, IL-12, and IL-18, only the Th1 cells markedly augmented IFN-gamma production in response to IL-18, suggesting that IL-18 responsiveness between Th1 and Th2 cells resulted from their differential expression of IL-18R.

Stem cell factor augments Fc epsilon RI-mediated TNF-alpha production and stimulates MAP kinases via a different pathway in MC/9 mast cells

Mast cells express the receptor tyrosine kinase kit/stem cell factor receptor (SCFR) which is encoded by the proto-oncogene c-kit. Ligation of SCFR induces its dimerization and activation of its intrinsic tyrosine kinase activity leading to activation of Raf-1, phospholipases, phosphatidylinositol 3-kinase, and extracellular signal-regulated kinases. However, little is known about the downstream signals initiated by SCFR ligation except for activation of extracellular signal-regulated kinases. The murine mast cell line, MC/9, synthesizes and secretes TNF-alpha following the aggregation of high affinity Fc receptors for IgE (Fc epsilonRI). Ligation of SCFR or Fc epsilonRI on MC/9 cells resulted in the activation of all three MAP kinase family members, extracellular signal-regulated kinases, c-Jun amino-terminal kinase (JNK), and p38. Stem cell factor (SCF)-induced activation of JNK and p38 was insensitive to wortmannin, cyclosporin A, and FK506 whereas activation of these kinases through Fc epsilonRI was sensitive to these drugs. Coligation of SCFR augmented Fc epsilonRI-mediated activation of MAP kinases, especially JNK activation, and SCF augmented Fc epsilonRI-mediated TNF-alpha production in MC/9 cells, although SCF alone did not induce TNF-alpha production. This augmentation by SCF was regulated at the level of transcription, at least in part, since the promoter activity of TNF-alpha was enhanced following addition of SCF. These results demonstrate that SCF can augment Fc epsilonRI-mediated JNK activation and cytokine gene transcription but via pathways that are regulated differently than the ones activated through Fc epsilonRI.

Aggressive non-Hodgkin's lymphoma after successful eradication of Helicobacter pylori and regression of gastric lymphoma of mucosa-associated lymphoid tissue

A 57-year-old woman presented to our clinic with low-grade gastric lymphoma of mucosa-associated lymphoid tissue (stage IE) and Helicobacter pylori infection. She received a 2-week course of omeprazole and clarithromycin, resulting in eradication of H. pylori and histological disappearance of the lymphoma. However, 9 months later (May 1996), multiple mass lesions were found around the pancreas and hepato-duodenal ligament on abdominal computed tomography. Inguinal lymph node biopsy revealed aggressive nodal type B-cell non-Hodgkin's lymphoma, diffuse large cell type. She received chemotherapy with cyclophosphamide, adriamycin, vincristine, and prednisolone, but failed to achieve remission and died in December 1996. There was no evidence of recurrent gastric lymphoma. This case emphasizes the importance of performing follow-up examinations to detect other neoplasms in patients with gastric lymphoma of mucosa-associated lymphoid tissue.

[Assessment of ischemic heart disease by dipyridamole stress electrocardiographic gated myocardial single photon emission computed tomography with technetium-99m tetrofosmin]

Simultaneous assessment of stress perfusion and rest function is possible with gated single photon emission computed tomography (SPECT) using stress injected technetium-99m (99mTc) tetrofosmin (TF). The feasibility of dipyridamole stress electrocardiographic gated myocardial SPECT (GSPECT) with TF was examined as an alternative to conventional stress/rest imaging. Fifty-one patients underwent stress GSPECT. 740 MBq of TF was administered 3 min after dipyridamole infusion. GSPECT acquisition was performed one hour after the injection. Additional rest SPECT was performed on another day only in patients with abnormal perfusion on stress images. Perfusion and thickening were analyzed visually on 17 segments of the left ventricle. Percentage of wall thickening (%WT) was also calculated in 17 segments of the polar map. Thirty-two of 51 patients (63%) had normal stress perfusion and normal rest thickening. Nineteen of 51 patients (37%) had abnormal perfusion on stress images. Among 157 abnormal perfusion segments of the 19 patients, 139 segments (89%) had thickening and the rest (11%) had no thickening. %WT was higher in the reversible segments with or without thickening. There was better agreement for the identification of normal segments and the presence of reversibility between stress GSPECT and the conventional stress/rest study in patients without previous myocardial infarction than in those with previous myocardial infarction (89% vs 79%). These results suggest that stress GSPECT may substitute for conventional stress/rest perfusion study in patients without previous myocardial infarction, allowing shorter examination time and lower cost. However, stress GSPECT does not replace the need for rest perfusion study in patients with previous myocardial infarction, because of underestimation of viability, but %WT may eliminate this underestimation.

Combination of irinotecan and etoposide for treatment of refractory or relapsed small-cell lung cancer

PURPOSE

To determine the response rate, survival, and toxicity of irinotecan (CPT-11), a topoisomerase I inhibitor, combined with etoposide, a topoisomerase II inhibitor, in refractory or relapsed small-cell lung cancer (SCLC).

PATIENTS AND METHODS

Twenty-five patients with refractory or relapsed SCLC were entered onto the trial. All 25 patients had been pretreated with some form of cisplatin-based combination chemotherapy and had also received previous etoposide- or anthracyclinecontaining chemotherapy. The median time off chemotherapy was 6.7 months (range, 0.9 to 23.5). Patients were treated at 4-week intervals using CPT-11 (a starting dose of 70 mg/m2 intravenously on days 1, 8, and 15) plus etoposide (80 mg/m2 intravenously on days 1 to 3), with a subsequent dose based on toxicity. In addition, recombinant human granulocyte colony-stimulating factor (rhG-CSF; 2 microg/kg/d) was given from day 4 to day 21, except on the days of CPT-11 administration.

RESULTS

All patients were assessable for toxicity and survival. Twenty-four patients were assessable for response. There were 14 partial responses (PRs) and three complete responses (CRs), for an overall response rate of 71% (95% confidence interval, 53% to 89%). The median response duration was 4.6 months. Median survival was 271 days. Major toxicities were myelosuppression (predominantly leukopenia) and diarrhea. Grade 3 to 4 neutropenia and thrombocytopenia occurred in 56% and 20% of patients, respectively. Grade 3 to 4 diarrhea was observed in 4%. There was one treatment-related death due to severe myelosuppression.

CONCLUSION

A combination of CPT-11 and etoposide with rhG-CSF support is an active therapy against refractory or relapsed SCLC and deserves to be studied more extensively in a phase III trial.

Alzheimer's disease with asymmetric parietal lobe atrophy: a case report

A 52-year-old, right-handed female presented with visuospatial dysfunction including left hemineglect, incomplete Balint's syndrome, and environmental agnosia, together with left-sided motor symptoms such as unskillful movement, dystonic postures, and myoclonus in the left hand, without significant dementia. Symptoms progressed to akinetic mutism prior to her death 10 years after onset of illness. Imaging studies such as MRI, SPECT, and PET studies showed severe, predominantly right-sided involvement of parietal and parieto-occipital areas. The motor signs might originate from the right parietal lesions such as area five or somatosensory area. Neuropathologic studies including immunocytochemistry showed tau-positive neurofibrillary tangles and abundant neuritic plaques with amyloid deposits, confirming the diagnosis of Alzheimer's disease. An analysis of serum apolipoprotein E revealed epsilon3/epsilon3 homozygosity. This case represents a variant of Alzheimer's disease conspicuous for progressive motor signs and visuospatial dysfunction with a striking laterality, reflecting asymmetric parietal involvement. Alzheimer's disease with asymmetric parietal atrophy is difficult to be clinically distinguished from corticobasal degeneration characterized by progressive unilateral motor signs and focal cortical signs.

ASK1 is essential for JNK/SAPK activation by TRAF2

Tumor necrosis factor (TNF)-induced activation of the c-jun N-terminal kinase (JNK, also known as SAPK; stress-activated protein kinase) requires TNF receptor-associated factor 2 (TRAF2). The apoptosis signal-regulating kinase 1 (ASK1) is activated by TNF and stimulates JNK activation. Here we show that ASK1 interacts with members of the TRAF family and is activated by TRAF2, TRAF5, and TRAF6 overexpression. A truncated derivative of TRAF2, which inhibits JNK activation by TNF, blocks TNF-induced ASK1 activation. A catalytically inactive mutant of ASK1 is a dominant-negative inhibitor of TNF- and TRAF2-induced JNK activation. In untransfected mammalian cells, ASK1 rapidly associates with TRAF2 in a TNF-dependent manner. Thus, ASK1 is a mediator of TRAF2-induced JNK activation.

Increase in the expression of biglycan mRNA expression Co-localized closely with that of type I collagen mRNA in the infarct zone after experimentally-induced myocardial infarction in rats

Biglycan, a small dermatan sulphate proteoglycan, has been postulated to interact with other components of the extracellular matrix (ECM), specifically collagens. We hypothesized that biglycan messenger ribonucleic acid (mRNA) is increased in the myocardial infarct zone. Biglycan mRNA expression after acute myocardial infarction (AMI) in rats was determined with the use of Northern blotting and in situ hybridization, and its expression pattern was compared to that of type I collagen mRNA [alpha1(I) collagen]. The left coronary artery was ligated in male Sprague-Dawley rats, and the hearts were excised on days 2 and 7. The Northern blot analysis demonstrated that expression of biglycan mRNA in the infarct on days 2 and 7 were 4.0- and 6.8-fold higher, respectively, compared to the sham-operated hearts. The in situ hybridization revealed intense signals for both biglycan and alpha1(I) collagen mRNA on day 2 in the spindle-shaped mesenchymal cells located between the surviving myocytes in the infarct peripheral zone. On day 7, biglycan mRNA signals were observed in the interior of the infarct around the infarct granulation tissue, a distribution that was essentially the same as that of alpha1(I) collagen. These results demonstrated that the increases in the infarct biglycan mRNA expression produced by mesenchymal cells (presumably myofibroblasts and fibroblasts) was closely co-localized with that of type I collagen mRNA, indicating that biglycan contributes to the infarct healing processes.

Disadvantage of long-term CAPD for preserving cardiac performance: an echocardiographic study

The indices of cardiac performances were compared between 31 continuous ambulatory peritoneal dialysis (CAPD) and 20 long-term hemodialysis (HD) patients. They were subdivided into three groups according to dialysis duration: L-CAPD (n = 16, mean age and CAPD duration were, respectively, 53 +/- 8 [SD] years and 77 +/- 13 months); S-CAPD (n = 15; 52 +/- 12 years, 28 +/- 12 months); HD (n = 20; 51 +/- 10 years, 162 +/- 52 months). The diabetic HD patients (DM-HD; n = 13; 60 +/- 13 years of age, 22 +/- 11 months) were chosen separately. Thirteen normotensive subjects with normal kidney function (mean age, 57 +/- 9 years) were selected as an age-matched control group. There were no significant differences between groups in age, gender, incidence of original kidney disease, or serum biochemical data. The blood pressure and the cardiothoracic ratio in L-CAPD were highest among groups. The indices of left ventricular (LV) hypertrophy as well as LV performance by means of echocardiography or pulsed Doppler were compared. Among nondiabetic dialysis patients, the calculated LV mass index (LVMI) of 166.4 +/- 84.3 g/m2 and the ratio of the peak atrial filling velocity to the peak diastolic flow velocity of 1.25 +/- 0.4 in L-CAPD were greatest, and the left ventricular fractional shortening (%FS) of 34.2 +/- 10.8% in L-CAPD was smallest. LVMI or %FS of L-CAPD was the same as DM-HD of 161.0 +/- 40.7 g/m2 or 31.6 +/- 8.2%. Possibly, poor control of hypervolemia, which is caused by peritoneal problems induced by either peritonitis or chronic exposure to high-glucose dialysate, causes a substantial cardiac preload leading to incipient cardiac failure in L-CAPD. According to the similar results of L-CAPD and DM-HD, it may be that hypertension, hyperlipidemia, or long-term constant glucose loading of CAPD fluids in addition to impaired glucose tolerance by chronic renal failure is more or less related to the progression of LV hypertrophy and latent cardiac dysfunction in long-term CAPD patients. In this context, CAPD of more than 5 years' duration is disadvantageous for preserving cardiac function as compared with HD.