[Biweekly low-dose cisplatin and 5-fluorouracil combination chemotherapy for advanced gastrointestinal carcinoma]

Biweekly intravenous infusions of low-dose cisplatin (CDDP) and 5-fluorouracil (5-FU) were evaluated in 80 patients with advanced or recurrent gastric, colorectal, pancreatic or gallbladder adenocarcinoma. CDDP was given biweekly at a dose of 15 mg/m2 infused for 30 minutes, and 5-FU 375 mg/m2 was infused for 2 hours as many times as possible. The response rate among patients with gastric cancer was 26%, colorectal cancer 10%, pancreatic cancer 7.7%, and gallbladder cancer 42.9%. The response rates were not so high, but the median survival time of patients with recurrent gastric cancer was 17.3 months, pancreatic cancer 6.7 months, and gallbladder cancer 10.7 months. A patient with unresected advanced pancreatic head cancer with liver and para-aortic lymph node metastases received this therapy 38 times, and lived for 54 months. No severe side effects occurred in any of these cases. Thus, this chemotherapy could well be effective for the outcome of cases of advanced gastrointestinal carcinoma.

Nerve growth factor-induced neuronal differentiation requires generation of Rac1-regulated reactive oxygen species

Nerve growth factor (NGF) stimulation of pheochromocytoma PC12 cells transiently increased the intracellular concentration of reactive oxygen species (ROS). This increase was blocked by the chemical antioxidant N-acetylcysteine and a flavoprotein inhibitor, diphenylene iodonium. NGF responses of PC12 cells, including neurite outgrowth, tyrosine phosphorylation, and AP-1 activation, was inhibited when ROS production was prevented by N-acetylcysteine and diphenylene iodonium. The expression of dominant negative Rac1N17 blocked induction of both ROS generation and morphological differentiation by NGF. The ROS produced appears to be H(2)O(2), because the introduction of catalase into the cells abolished NGF-induced neurite outgrowth, ROS production, and tyrosine phosphorylation. These results suggest that the ROS, perhaps H(2)O(2), acts as an intracellular signal mediator for NGF-induced neuronal differentiation and that NGF-stimulated ROS production is regulated by Rac1 and a flavoprotein-binding protein similar to the phagocytic NADPH oxidase.

Multiple discontinuous ligand-mimetic antibody binding sites define a ligand binding pocket in integrin alpha(IIb)beta(3)

Integrin alpha(IIb)beta(3), a platelet fibrinogen receptor, is critically involved in thrombosis and hemostasis. However, how ligands interact with alpha(IIb)beta(3) has been controversial. Ligand-mimetic anti-alpha(IIb)beta(3) antibodies (PAC-1, LJ-CP3, and OP-G2) contain the RGD-like RYD sequence in their CDR3 in the heavy chain and have structural and functional similarities to native ligands. We have located binding sites for ligand-mimetic antibodies in alpha(IIb) and beta(3) using human-to-mouse chimeras, which we expect to maintain functional integrity of alpha(IIb)beta(3). Here we report that these antibodies recognize several discontinuous binding sites in both the alpha(IIb) and beta(3) subunits; these binding sites are located in residues 156-162 and 229-230 of alpha(IIb) and residues 179-183 of beta(3). In contrast, several nonligand-mimetic antibodies (e.g. 7E3) recognize single epitopes in either subunit. Thus, binding to several discontinuous sites in both subunits is unique to ligand-mimetic antibodies. Interestingly, these binding sites overlap with several (but not all) of the sequences that have been reported to be critical for fibrinogen binding (e.g. N-terminal repeats 2-3 but not repeats 4-7, of alpha(IIb)). These results suggest that ligand-mimetic antibodies and probably native ligands may make direct contact with these discontinuous binding sites in both subunits, which may constitute a ligand-binding pocket.

Morphologic abnormalities in the brain of chronically hemodialyzed patients without cerebrovascular disease

In this study, the authors evaluated the cerebral atrophy in 56 chronic hemodialyzed patients, who did not have clinical episodes or radiologic findings of cerebrovascular diseases, and 42 controls. Using computed tomography (CT) images, brain atrophy index (BAI), the proportion of subarachnoidal plus ventricular space in the cranial cavity, and ventricular area index (VAI), percent area of ventricle in the brain, were calculated. CT of the brain demonstrated an age-dependent increase in BAI in both hemodialyzed patients and controls. BAI and VAI were greater in hemodialyzed patients than healthy controls and the difference was significant at ages under 60 years in BAI and at ages less than 50 years in VAI. The atrophy of the frontal parts of the brain in patients on hemodialysis for 10 years or more was significantly greater than in patients dialyzed for less than 10 years. There was a significant negative correlation between BAI or VAI and hematocrit. These findings indicate that renal failure or hemodialysis itself might cause cerebral atrophy, and that the cerebral atrophy is more prominent in patients on hemodialysis for a long duration and with low hematocrit.

[Suicidal attempts in three postoperative patients with renal cancer after alpha interferon withdrawal]

We report 3 cases of suicide attempts in postoperative patients with renal cancer after alpha interferon withdrawal. In the first patient, depression occurred during interferon therapy, and remained after interferon withdrawal. A suicide attempt occurred 7 months after interferon withdrawal. In the second and third patients, depression did not occur during interferon therapy, but suicide attempts occurred 40 days and 7 months after interferon withdrawal, respectively. Depression does not always disappear after interferon is discontinued. Psychiatric supervision should be continued even more frequently after interferon withdrawal. The increased risk of psychiatric side effects due to interferon, as well as their severity, suggest that interferon should be administered with caution.

[A case of significant natriuresis and improvement of proteinuria by Temocapril, an ACE inhibitor with biliary excretion, in loop diuretics resistant edema in membranous nephropathy]

A 50-year-old man with WPW syndrome and chronic atrial fibrillation controlled by digoxin exhibited nephrotic syndrome due to membranous nephropathy in 1994. For massive edema resistant to loop diuretics, administration of 2 mg/day of Temocapril, an ACE inhibitor with biliary excretion, was started. It provided marked natriuresis and rapid improvement of massive anasarca. Moreover, 6 months later at the time of writing this report, nephrotic proteinuria has decreased and abnormally depressed Ccr level has elevated. For massive edema resistant to loop diuretics in nephrotic syndrome, Temocapril might bring about a beneficial effect possibly through the induction of natriuresis, which has been suppressed by the over-expression of angiotensin II in tubulointerstitium.

Interaction between collagen and the alpha(2) I-domain of integrin alpha(2)beta(1). Critical role of conserved residues in the metal ion-dependent adhesion site (MIDAS) region

A docking model of the alpha(2) I-domain and collagen has been proposed based on their crystal structures (Emsley, J., King, S., Bergelson, J., and Liddington, R. C. (1997) J. Biol. Chem. 272, 28512-28517). In this model, several amino acid residues in the I-domain make direct contact with collagen (Asn-154, Asp-219, Leu-220, Glu-256, His-258, Tyr-285, Asn-289, Leu-291, Asn-295, and Lys-298), and the protruding C-helix of alpha(2) (residues 284-288) determines ligand specificity. Because most of the proposed critical residues are not conserved, different I-domains are predicted to bind to collagen differently. We found that deleting the entire C-helix or mutating the predicted critical residues had no effect on collagen binding to whole alpha(2)beta(1), with the exception that mutating Asn-154, Asp-219, and His-258 had a moderate effect. We performed further studies and found that mutating the conserved surface-exposed residues in the metal ion-dependent adhesion site (MIDAS) (Tyr-157 and Gln-215) significantly blocks collagen binding. We have revised the docking model based on the mutagenesis data. In the revised model, conserved Tyr-157 makes contact with collagen in addition to the previously proposed Asn-154, Asp-219, His-258, and Tyr-285 residues. These results suggest that the collagen-binding I-domains (e.g. alpha(1), alpha(2), and alpha(10)) bind to collagen in a similar fashion.

Ultrastructural localization of dominantly increased fibronectin in the markedly thickened glomerular basement membrane in a selectively mated murine high IgA strain (HIGA mice)

To clarify which matrix component(s) contributes to glomerular sclerosis with mesangial IgA deposits in a murine high serum IgA strain (HIGA) derived from ddY mice, morphological and immunopathological analyses of glomeruli were performed in comparison with original ddY and BALB/c mice as controls. Significantly increased thickness of the glomerular basement membrane (GBM), especially the lamina densa, was observed in HIGA mice. Immunofluorescent staining showed marked increases in levels of fibronectin and laminin in both the mesangium and capillary wall in aged HIGA mice. Analysis of the distribution of immunogold-labeled antibody in GBM revealed a significant increase (p < 0.0001) and specific orientation of fibronectin in the endothelial side, which suggested that mesangial fibronectin produced at high levels due to IgA deposition extended to the endothelial side of GBM and contributed to the thickening of GBM with further development to glomerulosclerosis in the HIGA mice.

Cloning and expression of yellowtail ascites virus segment A

cDNA of yellowtail ascites virus (YAV) segment A encoding a polyprotein of VP2, NS, and VP3 has been cloned. Comparison of the nucleotide and the deduced amino acid sequences showed very high homology between YAV and other aquatic birnaviruses. The two small open reading frames (VP5) besides the 5' terminus of the VP2 gene were found on segment A of YAV. Proteins encoded by cDNAs from segment A and the serotype-specific epitope region on VP2 were expressed using a baculovirus vector. Western blot analysis confirmed that a polyprotein was expressed and processed into VP2 and VP3 in insect cells infected with the recombinant baculovirus containing the complete polyprotein coding region. In the case of expression in silkworm larvae, only VP3 was detected in hemocytes and fat body of silkworm larvae infected with the recombinant virus. The recombinant fusion protein consisting of VP2 epitope region and polyhedrin was expressed in insect cells and cross-reacted with a mouse monoclonal antibody against VP2 which had a neutralizing activity to YAV.

[Nephrostomy of which catheter can be introduced from the abdominal wall]

AIM OF STUDY

The aim of this study is to find out the method for the nephrostomy of which catheter can be introduced from the abdominal wall.

METHODS

Subjects were the 7 patients whose agreement for this new method could be obtained. After the general nephrostomy was performed, 3 cm skin incision to the outer portion of nephrostomy, as well as 5 mm skin incision to the abdominal wall were added, and the subcutaneous tunnel between the both skin incisions was made using the special tunneler. A guide wire was introduced into the renal pelvis through the subcutaneous tunnel, and then 14 F Maleocot catheter was introduced from the abdominal skin incision to the renal pelvis. At the skin incision of the nephrostomy, catheter and subcutaneous tissue were fixed using 3-0 cutgut suture to prevent the outcomming of the catheter.

RESULTS

In case 1 to case 4 showed some trouble, but case 5 to 7 showed no trouble. The operation time and the extent of invasion of our method were as well as that of the general nephrostomy, but the managements by the patients were as simple as that of the ureterocutaneostomy.

CONCLUSION

The quality of our patients seem to close to that of uretero-cutaneostomy. And for the patients who have hydronephrosis after several type of urinary diversions, our method should be recommendable than the general nephrostomy.

An inherited prion disease with a PrP P105L mutation: clinicopathologic and PrP heterogeneity

OBJECTIVE

To clarify a clinical and neuropathologic phenotype of an inherited prion disease associated with a missense mutation at codon 105 in the prion protein (PrP) gene that was originally described as a variant of Gerstmann-Sträussler-Scheinker disease demonstrating spastic paraparesis.

METHODS

Two siblings from a Japanese family are described. PrP gene analyses, neuropathologic studies with immunohistochemistry, and Western blot analysis of the PrP were performed.

RESULTS

Both patients showed a missense (proline-->leucine) mutation at codon 105 and a methionine/valine polymorphism at codon 129 of the PrP gene. Clinically, Patient 1 presented with progressive spastic paraparesis, ataxia, and dementia. Patient 2, the sister of Patient 1, showed prominent action myoclonus and dementia. Neuropathologically, multiple PrP-positive amyloid plaques and diffuse PrP deposition in the deep cortical layers were found in the cerebral cortex with primarily frontal dominant atrophy in both patients. Tau-positive pathologic structures including neurofibrillary tangles, neuropil threads, and dystrophic neurites around the plaques were abundant in the brain of Patient 2. In contrast, the tau pathology was scarce in Patient 1. Western blot analysis of the brain showed different patterns of detergent-insoluble PrP fragments between the patients.

CONCLUSIONS

Despite the identical codon 105 mutation and codon 129 polymorphism of the PrP gene, remarkable clinical and neuropathologic differences, and PrP heterogeneity were present between the affected siblings. The phenotypic variability might be related to PrP heterogeneity.

Direct inhibitory effects of simvastatin on matrix accumulation in cultured murine mesangial cells

BACKGROUND

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been demonstrated to suppress glomerular injuries in various renal diseases. These agents inhibit in vitro proliferation of several cell types, including mesangial cells. This effect indicates the ability to ameliorate mesangioproliferative lesions, independent of the improvement of hypercholesterolemia. On the other hand, it is not clear whether HMG-CoA reductase inhibitors directly regulate extracellular matrix (ECM) accumulation from mesangial cells.

METHODS

In this study, to examine the in vitro effects of simvastatin, an HMG-CoA reductase inhibitor, on mRNA expressions of matrix proteins, growth factors, and matrix turnover proteins, we incubated cultured murine mesangial cells stimulated by fetal calf serum (FCS) with or without simvastatin for 24 hours, and Northern analysis was performed.

RESULTS

Simvastatin showed a slightly suppressive effect on mRNA expression of type IV collagen and fibronectin and a slightly up-regulative effect on that of type I collagen, whereas mRNA expression of type III collagen was markedly up-regulated. mRNA expression of platelet-derived growth factor (PDGF)-B chain and PDGF receptor beta-subunit was suppressed, whereas that of transforming growth factor-beta (TGF-beta) was not affected by simvastatin. Concerning matrix turnover proteins, simvastatin markedly reduced mRNA expression of plsminogen activator inhibitor-1 (PAI-1) without affecting the expression of tissue-type plasminogen activator (tPA).

CONCLUSION

These results suggest type-specific modulation of matrix protein production independent of TGF-beta and the suppressive effects of autocrine PDGF by administration of HMG-CoA reductase inhibitors in mesangial cells. Moreover, the beneficial effects of these agents on matrix protein accumulation may be through promoting ECM degradation derived from PAI-1 suppression.

[Natural killer-like T-cell lymphoma appearing in the duodenum with recurrence in a variety of extranodal organs]

A 48-year-old man was admitted to Keio University Hospital in April 1995 with complaints of right abdominal pain and weight loss. Hypotonic duodenography showed a mass located in the 3rd portion of the duodenum. Endoscopic biopsy specimens disclosed diffuse large cell non-Hodgkin's lymphoma of the duodenum. The patient was initially treated with 2 courses of CHOP, albeit with no response. A pancreatoduodenectomy and radiotherapy yielded a complete remission. A year later, lymphoma recurred in the right mandible salivary gland, and a second complete remission was obtained after 6 courses of CHOP and radiation. However lymphomas also recurred in the intestine, and lungs, and the patient died of disease progression 38 months after diagnosis. Lymphoma cells were surface CD3 and CD56 positive. An examination of resected intestinal tissues disclosed lymphoma cells morphologically resemble large granular lymphocytes with rearranged TcR genes. These findings indicated the diagnosis of natural killer-like (NK-like) T-cell lymphoma. Compared with previously reported cases of NK-like T-cell lymphoma, this case was noteworthy for an unusual clinical course characterized by initial appearance in the duodenum, recurrence in a variety of extranodal organs, and the relatively long-term survival of the patient.

Isoform-specific insertion near the Grb2-binding domain modulates the intrinsic guanine nucleotide exchange activity of hSos1

Two human hSos1 isoforms (Isf I and Isf II; Rojas et al., Oncogene 12, 2291-2300, 1996) defined by the presence of a distinct 15 amino acid stretch in one of them, were compared biologically and biochemically using representative NIH3T3 transfectants overexpressing either one. We showed that hSos1-Isf II is significantly more effective than hSos1-Isf I to induce proliferation or malignant transformation of rodent fibroblasts when transfected alone or in conjunction with normal H-Ras (Gly12). The hSos1-Isf II-Ras cotransfectants consistently exhibited higher saturation density, lower cell-doubling times, increased focus-forming activity and higher ability to grow on semisolid medium and at low serum concentration than their hSos1-Isf I-Ras counterparts. Furthermore, the ratio of GTP/GDP bound to cellular p21ras was consistently higher in the hSos1-Isf II-transfected clones, both under basal and stimulated conditions. However, no significant differences were detected in vivo between Isf I- and Isf II-transfected clones regarding the amount, stability and subcellular localization of Sos1-Grb2 complex, or the level of hSos1 phosphorylation upon cellular stimulation. Interestingly, direct Ras guanine nucleotide exchange activity assays in cellular lysates showed that Isf II transfectants consistently exhibited about threefold higher activity than Isf I transfectants under basal, unstimulated conditions. Microinjection into Xenopus oocytes of purified peptides corresponding to the C-terminal region of both isoforms (encompassing the 15 amino acid insertion area and the first Grb2-binding motif) showed that only the Isf II peptide, but not its corresponding Isf I peptide, was able to induce measurable rates of meiotic maturation, and synergyzed with insulin, but not progesterone, in induction of GVBD. Our results suggest that the increased biological potency displayed by hSos1-Isf II is due to higher intrinsic guanine nucleotide exchange activity conferred upon this isoform by the 15 a.a. insertion located in proximity to its Grb2 binding region.

Midkine inhibits apoptosis via extracellular signal regulated kinase (ERK) activation in PC12 cells

Midkine (MK) is a new member of the family of heparin-binding neurotrophic factors. MK has several important biological effects and plays an important role in the development and survival of neurons. The mechanism by which MK exerts its neurotrophic actions, however has not been sufficiently clarified. To understand the intracellular pathway activated by MK, we established an apoptosis-induction system with the neuronal cell line PC12 and studied the involvement of the mitogen-activated protein kinase (MAPK) cascade in neuroprotective actions of MK. We demonstrate here that MK rescued PC12 cells from apoptosis induced by serum deprivation in a dose-dependent manner. MK also activated extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2), which are well known as signal transducer acting downstream several receptors. PD98059, an inhibitor of MAPK kinase (MAPKK), inhibited ERK activation and also prevented the trophic effect of MK. These results indicate that MK exerts its neuroprotective actions mainly via ERK activation.

Up-regulation of glomerular extracellular matrix and transforming growth factor-beta expression in RF/J mice

BACKGROUND

RF/J mice were first reported as a murine model of spontaneous glomerulosclerosis by Gude and Lupton in 1960, but the precise histologic characteristics and immunopathological background of this mouse have not been investigated further.

METHODS

Measurements of serum levels of immunoglobulins, anti-single strand DNA (anti-ss-DNA) antibody, complement (C3), and circulating immune complex (IC) were performed. Analyses of glomerular histological and immunopathological lesions in association with the detection of mRNA expression of collagen IV, TGF-beta, matrix protein turnover related enzymes, matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase-2 (TIMP-2) and platelet-derived growth factor (PDGF) were also performed in young (10-week-old) and elderly (60-week-old) RF/J mice with age-matched BALB/C mice as the controls.

RESULTS

High levels of serum IgA and IgG from as early as 20 weeks of age were noted in the RF/J mice. Serum anti-ss-DNA antibody of aged RF/J mice increased up to 23% of that of aged MRL-lpr/lpr mice, and serum C3 concentration significantly decreased with age, reaching lower levels than that of BALB/c mice. IgA-IC levels were significantly high compared to BALB/C mice both in the early and late stages of life, whereas IgG-IC levels were high only in mice younger than 20 weeks. Semiquantitative and quantitative analyzes of renal histopathological findings revealed significantly marked and age-related mesangial matrix expansion in RF/J mice, with increasing frequency of global glomerular sclerosis and tubulointerstitial damage. On the other hand, although precise measurements of glomerular cell numbers also showed an apparent augmentation in both young and old RF/J mice compared to BALB/C mice, glomerular cellularity decreased with age in RF/J mice. Immunohistochemical study revealed massive immunoglobulin deposition from a young age in association with significantly higher accumulation of matrix proteins, such as types I and IV collagen and laminin from the early stage of life. In addition, in these glomeruli, transforming growth factor-beta1 (TGF-beta1) was highly expressed both in young and old mice. The mRNA expression of MMP-2 was up-regulated only in the early stage of life. Although PDGF mRNA of RF/J mice was significantly up-regulated in the early stage of life, the differences between the mice disappeared in the late stage of life.

CONCLUSIONS

These findings suggest that in RF/J mice, an immunopathological background inducing high serum immunoglobulin and IC levels from the early stage of life is closely related to mesangioproliferative glomerular lesions mediated by PDGF, and that development of massive extracellular matrix accumulation in glomeruli was induced by up-regulated expression of TGF-beta with inappropriate regulation of protein turnover-related enzyme production.

Anomalous union of the pancreaticobiliary ductal system without dilation of the common bile duct or tumor: case reports and literature review

Among 698 patients subjected to endoscopic retrograde cholangiopancreatography, an anomalous union of the pancreaticobiliary ductal system (AUPBD) was found in 6 patients (0.9%). One of these 6 patients had an associated congenital choledochal cyst, and 4 did not. Two of these 4 patients, however, had advanced gallbladder cancer. The remaining 2 patients had no associated carcinoma of the biliary tract. A clinicopathological study was performed on these 2 patients and 26 such cases have been reported in the literature. The diagnosis of AUPBD was made by direct cholangiography. Regarding the type of union, the Pancreatic-Biliary type was present in 15 of 18 (83.3%) of these patients. Fifteen of 28 patients (53.6%) had right upper abdominal pain. Thickness of the gallbladder wall was visualized in 26 of the 28 (92.9%) patients. Gallstones were present in 4 (14.3%). AUPBD should always be kept in mind when a patient with abdominal pain is diagnosed as having gallbladder wall thickness without gallstones. ERCP should be performed in these patients in order to detect AUPBD without dilation of the bile duct. This may allow early detection of carcinoma of the biliary tract.

Effect of genetic differences in omeprazole metabolism on cure rates for Helicobacter pylori infection and peptic ulcer

BACKGROUND

Omeprazole is metabolized by S-mephenytoin 4'-hydroxylase (CYP2C19) in the liver. In persons with a poor-metabolizer genotype for CYP2C19, the therapeutic efficacy of omeprazole may be increased.

OBJECTIVE

To investigate whether CYP2C19 genotype status is associated with cure rates for Helicobacterpylori infection and peptic ulcer achieved by using dual therapy with omeprazole and amoxicillin.

DESIGN

Prospective cohort study.

SETTING

University hospital and health service center in Hamamatsu, Japan.

PATIENTS

62 patients with peptic ulcer and H. pylori infection.

INTERVENTION

Omeprazole and amoxicillin.

MEASUREMENTS

CYP2C19 genotype status and cure rates for H. pylori infection and peptic ulcer.

RESULTS

Cure rates for H. pylori infection were 28.6% (95% CI, 13.1% to 48.7%), 60% (CI, 38.6% to 83.0%), and 100% (CI, 66.4% to 100%) in the rapid-, intermediate-, and poor-metabolizer groups, respectively. Healing rates for both duodenal and gastric ulcer in the three groups were roughly parallel with cure rates for H. pylori infection.

CONCLUSION

The results of the genotyping test for CYP2C19 seem to predict cure of H. pylori infection and peptic ulcer in patients who receive dual therapy with omeprazole and amoxicillin.

Three novel integrin beta3 subunit missense mutations (H280P, C560F, and G579S) in thrombasthenia, including one (H280P) prevalent in Japanese patients

We analyzed three unrelated Japanese patients with type II Glanzmann thrombasthenia (GT) for associated mutations. Polymerase chain reaction and subsequent direct sequencing of platelet RNA and genomic DNA revealed three single nucleotide substitutions of the integrin beta3 subunit gene (His (CAT)-280 to Pro (CCT), Cys (TGT)-560 to Phe (TTT), and Gly(GGC)-579 to Ser(AGC)). Interestingly, the three unrelated patients all had the H280P mutation; one was homozygous and the other two heterozygous for this mutation. Ectopic expression of wild type and mutant complexes in Chinese hamster ovary cells revealed decreased surface expression of the mutated alphaIIbbeta3 complexes, thus demonstrating that these mutations may result in the mild GT phenotypes. The identification of three unrelated patients having the same mutation (H280P) suggests that this mutation might be prevalent in the Japanese thrombasthenic population.

Novel point mutations in the alphaIIb subunit (Phe289-->Ser, Glu324-->Lys and Gln747-->Pro) causing thrombasthenic phenotypes in four Japanese patients

We analysed the molecular basis of Glanzmann thrombasthenia (GT) in four Japanese patients with type I or type II disease. Polymerase chain reaction (PCR) and subsequent direct sequencing of platelet RNA and genomic DNA revealed three single nucleotide substitutions of the alphaIIb gene, which were confirmed by allele-specific PCR or restriction analysis. One patient with type I GT had a T to C base substitution in exon 11 resulting in a Phe (TTT)-289 to Ser (TCT) mutation (F289S) of the subunit. Another type I patient had a G to A base substitution in exon 12 resulting in a Glu (GAA)-324 to Lys (AAA) mutation (E324K). Interestingly, two unrelated patients with type II GT shared an A to C base substitution in exon 2 3, a region previously not associated with GT, resulting in a Gln (CAA)-747 to Pro (CCA) mutation (Q747P). To analyse the effects of these mutations on alphaII(b)beta3 surface expression, the wild-type alphaIIb cDNA or mutant alphaIIb cDNAs were transfected into Chinese hamster ovary (CHO) cells together with a wild-type beta3 cDNA. Flow cytometric analysis using an anti-alphaII(b)beta3 complex antibody revealed that 50.6% of CHO cells with wild-type alphaII(b)beta3 expressed complexes, whereas only 1 6%, 7.7% and 31.3% of cells, with IIb(F289S)beta3, alphaIIb(E324K)beta3 and alphaIIb(Q747P)beta3 expressed complexes, respectively. Our data indicate that these three novel point mutations in the alphaIIb subunit may hamper surface expression of the alphaII(b)beta3 complex, thus resulting in the quantitative GT phenotypes of platelets from these patients.

Xenopus CRMP-2 is an early response gene to neural induction

A neural specific protein, CRMP-2 (for Collapsin Response Mediator Protein-2), is considered to mediate collapsin-induced growth cone collapse during neural development. We have isolated the Xenopus homologue of the CRMP-2 (XCRMP-2) cDNA and studied the expression of XCRMP-2 mRNA and protein during neural induction. Induction of XCRMP-2 mRNA and protein expression, like N-CAM, occurred at the midgastrula stage and increased through early neural developmental stages. Whole mount in situ hybridization demonstrated that expression of XCRMP-2 mRNA was localized in neural tissues such as the neural plate and tube at early stages, while its expression in the brain, spinal cord, and eyes was observed at later stages. Immunostaining of Xenopus embryos with the antibody against CRMP-2 also showed that the protein was specifically expressed in the neural tissues at early stages. XCRMP-2 expression was induced by neural inducers such as noggin and chordin which antagonize a neural inhibitor, BMP4. A dominant negative BMP receptor also induced XCRMP-2 expression, suggesting that transcription of XCRMP-2 gene was negatively regulated by the BMP4 signaling. These results indicate that expression of XCRMP-2 is an early response marking neural commitment, and that transcriptional control of XCRMP-2 gene, is one of the targets of BMP4 signaling.