Crystal structure of human serum albumin at 2.5 A resolution

A new triclinic crystal form of human serum albumin (HSA), derived either from pool plasma (pHSA) or from a Pichia pastoris expression system (rHSA), was obtained from polyethylene glycol 4000 solution. Three-dimensional structures of pHSA and rHSA were determined at 2.5 A resolution from the new triclinic crystal form by molecular replacement, using atomic coordinates derived from a multiple isomorphous replacement work with a known tetragonal crystal form. The structures of pHSA and rHSA are virtually identical, with an r.m. s. deviation of 0.24 A for all Calpha atoms. The two HSA molecules involved in the asymmetric unit are related by a strict local twofold symmetry such that the Calpha atoms of the two molecules can be superimposed with an r.m.s. deviation of 0.28 A in pHSA. Cys34 is the only cysteine with a free sulfhydryl group which does not participate in a disulfide linkage with any external ligand. Domains II and III both have a pocket formed mostly of hydrophobic and positively charged residues and in which a very wide range of compounds may be accommodated. Three tentative binding sites for long-chain fatty acids, each with different surroundings, are located at the surface of each domain.

Essential Bacillus subtilis genes

To estimate the minimal gene set required to sustain bacterial life in nutritious conditions, we carried out a systematic inactivation of Bacillus subtilis genes. Among approximately 4,100 genes of the organism, only 192 were shown to be indispensable by this or previous work. Another 79 genes were predicted to be essential. The vast majority of essential genes were categorized in relatively few domains of cell metabolism, with about half involved in information processing, one-fifth involved in the synthesis of cell envelope and the determination of cell shape and division, and one-tenth related to cell energetics. Only 4% of essential genes encode unknown functions. Most essential genes are present throughout a wide range of Bacteria, and almost 70% can also be found in Archaea and Eucarya. However, essential genes related to cell envelope, shape, division, and respiration tend to be lost from bacteria with small genomes. Unexpectedly, most genes involved in the Embden-Meyerhof-Parnas pathway are essential. Identification of unknown and unexpected essential genes opens research avenues to better understanding of processes that sustain bacterial life.

Mammalian Cry1 and Cry2 are essential for maintenance of circadian rhythms

Many biochemical, physiological and behavioural processes show circadian rhythms which are generated by an internal time-keeping mechanism referred to as the biological clock. According to rapidly developing models, the core oscillator driving this clock is composed of an autoregulatory transcription-(post) translation-based feedback loop involving a set of 'dock' genes. Molecular clocks do not oscillate with an exact 24-hour rhythmicity but are entrained to solar day/night rhythms by light. The mammalian proteins Cryl and Cry2, which are members of the family of plant blue-light receptors (cryptochromes) and photolyases, have been proposed as candidate light receptors for photoentrainment of the biological clock. Here we show that mice lacking the Cryl or Cry2 protein display accelerated and delayed free-running periodicity of locomotor activity, respectively. Strikingly, in the absence of both proteins, an instantaneous and complete loss of free-running rhythmicity is observed. This suggests that, in addition to a possible photoreceptor and antagonistic clock-adjusting function, both proteins are essential for the maintenance of circadian rhythmicity.

Morphogenesis and renewal of hair follicles from adult multipotent stem cells

The upper region of the outer root sheath of vibrissal follicles of adult mice contains multipotent stem cells that respond to morphogenetic signals to generate multiple hair follicles, sebaceous glands, and epidermis, i.e., all the lineages of the hairy skin. At the time when hair production ceases and when the lower region of the follicle undergoes major structural changes, the lower region contains a significant number of clonogenic keratinocytes, and can then respond to morphogenetic signals. This demonstrates that multipotent stem cells migrate to the root of the follicle to produce whisker growth. Moreover, our results indicate that the clonogenic keratinocytes are closely related, if not identical, to the multipotent stem cells, and that the regulation of whisker growth necessitates a precise control of stem cell trafficking.

Randomised trial of effects of interferon-alpha on incidence of hepatocellular carcinoma in chronic active hepatitis C with cirrhosis

Patients with chronic active hepatitis C and cirrhosis often develop hepatocellular carcinoma. Interferon (IFN) seems to be effective in some patients but whether it prevents carcinogenesis is unknown. In a prospective randomised controlled trial, we evaluated the effects of IFN-alpha in cirrhotic patients with HCV infection because of their high risk of hepatocellular carcinoma. 90 patients with compensated chronic active hepatitis C with cirrhosis were randomly allocated to receive IFN-alpha (6 MU three times weekly for 12-24 weeks) (45 patients) or symptomatic treatment (45 controls), and were followed up for 2-7 years. In nine controls, alanine aminotransferase (ALT) decreased to less than 80 IU/L but did not stay in the normal range. In 19 patients given IFN-alpha, ALT decreased to less than 80 IU/L (in seven patients, it became and stayed normal; p = 0.011, Wilcoxon rank-sum test). However, the mean change in ALT was not significantly different between the two groups. The mean change in peak alpha-fetoprotein values was smaller in patients given IFN-alpha than in controls (p = 0.021). The mean change in the serum albumin level was higher in the IFN-alpha group (p < 0.001). The histological activity index in the 12 IFN-alpha patients undergoing a second biopsy after therapy was improved (p = 0.031). Hepatitis C viral RNA disappeared in seven (16%) of the 45 IFN-alpha patients (95% CI, 7-29%) and in none of the 45 controls (0-8%; p = 0.018). Hepatocellular carcinoma was detected in two (4%, 1-15%) IFN-alpha patients and 17 (38%, 24-54%) controls (p = 0.002, Wilcoxon signed-rank test). The risk ratio of IFN-alpha treatment versus symptomatic treatment was 0.067 (0.009-0.530; p = 0.010 Cox's proportional hazards). IFN-alpha improved liver function in chronic active hepatitis C with cirrhosis, and its use was associated with a decreased incidence of hepatocellular carcinoma.

Minocycline selectively inhibits M1 polarization of microglia

Minocycline is commonly used to inhibit microglial activation. It is widely accepted that activated microglia exert dual functions, that is, pro-inflammatory (M1) and anti-inflammatory (M2) functions. The in vivo status of activated microglia is probably on a continuum between these two extreme states. However, the mechanisms regulating microglial polarity remain elusive. Here, we addressed this question focusing on minocycline. We used SOD1^G93A mice as a model, which exhibit the motor neuron-specific neurodegenerative disease, amyotrophic lateral sclerosis. Administration of minocycline attenuated the induction of the expression of M1 microglia markers during the progressive phase, whereas it did not affect the transient enhancement of expression of M2 microglia markers during the early pathogenesis phase. This selective inhibitory effect was confirmed using primary cultured microglia stimulated by lipopolysaccharide (LPS) or interleukin (IL)-4, which induced M1 or M2 polarization, respectively. Furthermore, minocycline inhibited the upregulation of NF-κB in the LPS-stimulated primary cultured microglia and in the spinal cord of SOD1^G93A mice. On the other hand, IL-4 did not induce upregulation of NF-κB. This study indicates that minocycline selectively inhibits the microglia polarization to a proinflammatory state, and provides a basis for understanding pathogeneses of many diseases accompanied by microglial activation.

Glial growth factors are alternatively spliced erbB2 ligands expressed in the nervous system

Glial growth factors, proteins that are mitogenic for Schwann cells, and several ligands for the p185erbB2 receptor, are products of the same gene. Alternative splicing of the messenger RNA generates an array of putative membrane-attached, intracellular and secreted signalling proteins, at least some of which are expressed in the developing spinal cord and brain. These factors are probably important in the development and regeneration of the nervous system.

Results of surgical and nonsurgical treatment for small-sized hepatocellular carcinomas: a retrospective and nationwide survey in Japan. The Liver Cancer Study Group of Japan

Hepatic resection (HX), percutaneous ethanol injection (PEI), and transcatheter arterial embolization (TCAE) have all been used in the treatment of patients with small-sized hepatocellular carcinomas (HCCs). However, the indications for these therapeutic modalities remain unclear. Therefore, the first step to minimize the debate on these indications is to review the standard results from each treatment based on an extensive survey. The participants in this study were patients with HCCs less than 5 cm in diameter who were enrolled in The Liver Cancer Study Group of Japan. The survival rates in the HX (n = 8,010), PEI (n = 4,037), and TCAE (n = 841) groups were calculated in relation to the number of tumors and the clinical stage. In the clinical stage I cases with a solitary tumor less than 2 cm in diameter and in all clinical stages with a solitary tumor greater than 2 cm and in the clinical stage II cases with 2 tumors greater than 2 cm, the HX group showed higher survival rates than the nonsurgical groups. The HX group had a higher male/female ratio and a younger mean age than the PEI or TCAE group. The ratio of HBs antigen-positive cases/hepatitis C virus antibody-positive cases in the PEI group was lower than that in the corresponding HX group. In contrast, the PIVKA-II values in the HX group tended to be higher than in the PEI group. In conclusion, these findings will provide useful information for selection of a therapeutic modality for small-sized HCCs.

Muscular dystrophy and neuronal migration disorder caused by mutations in a glycosyltransferase, POMGnT1

Muscle-eye-brain disease (MEB) is an autosomal recessive disorder characterized by congenital muscular dystrophy, ocular abnormalities, and lissencephaly. Mammalian O-mannosyl glycosylation is a rare type of protein modification that is observed in a limited number of glycoproteins of brain, nerve, and skeletal muscle. Here we isolated a human cDNA for protein O-mannose beta-1,2-N-acetylglucosaminyltransferase (POMGnT1), which participates in O-mannosyl glycan synthesis. We also identified six independent mutations of the POMGnT1 gene in six patients with MEB. Expression of most frequent mutation revealed a great loss of the enzymatic activity. These findings suggest that interference in O-mannosyl glycosylation is a new pathomechanism for muscular dystrophy as well as neuronal migration disorder.

Standard steroid treatment for autoimmune pancreatitis

OBJECTIVE

To establish an appropriate steroid treatment regimen for autoimmune pancreatitis (AIP).

METHODS

A retrospective survey of AIP treatment was conducted in 17 centres in Japan. The main outcome measures were rate of remission and relapse.

RESULTS

Of 563 patients with AIP, 459 (82%) received steroid treatment. The remission rate of steroid-treated AIP was 98%, which was significantly higher than that of patients without steroid treatment (74%, 77/104; p<0.001). Steroid treatment was given for obstructive jaundice (60%), abdominal pain (11%), associated extrapancreatic lesions except the biliary duct (11%), and diffuse enlargement of the pancreas (10%). There was no relationship between the period necessary to achieve remission and the initial dose (30 mg/day vs 40 mg/day) of prednisolone. Maintenance steroid treatment was given in 377 (82%) of 459 steroid-treated patients, and steroid treatment was stopped in 104 patients. The relapse rate of patients with AIP on maintenance treatment was 23% (63/273), which was significantly lower than that of patients who stopped maintenance treatment (34%, 35/104; p = 0.048). From the start of steroid treatment, 56% (55/99) relapsed within 1 year and 92% (91/99) relapsed within 3 years. Of the 89 relapsed patients, 83 (93%) received steroid re-treatment, and steroid re-treatment was effective in 97% of them.

CONCLUSIONS

The major indication for steroid treatment in AIP is the presence of symptoms. An initial prednisolone dose of 0.6 mg/kg/day, is recommend, which is then reduced to a maintenance dose over a period of 3-6 months. Maintenance treatment with low-dose steroid reduces but dose not eliminate relapses.

Decreased prefrontal dopamine D1 receptors in schizophrenia revealed by PET

Schizophrenia is believed to involve altered activation of dopamine receptors, and support for this hypothesis comes from the antipsychotic effect of antagonists of the dopamine D2 receptor (D2R). D2R is expressed most highly in the striatum, but most of the recent positron emission tomography (PET) studies have failed to show any change in D2R densities in the striatum of schizophrenics, raising the possibility that other receptors may also be involved. In particular, the dopamine D1 receptor (D1R), which is highly expressed in the prefrontal cortex, has been implicated in the control of working memory, and working memory dysfunction is a prominent feature of schizophrenia. We have therefore used PET to examine the distribution of D1R and D2R in brains of drug-naive or drug-free schizophrenic patients. Although no differences were observed in the striatum relative to control subjects, binding of radioligand to D1R was reduced in the prefrontal cortex of schizophrenics. This reduction was related to the severity of the negative symptoms (for instance, emotional withdrawal) and to poor performance in the Wisconsin Card Sorting Test. We propose that dysfunction of D1R signalling in the prefrontal cortex may contribute to the negative symptoms and cognitive deficits seen in schizophrenia.

Updated overall survival results from a randomized phase III trial comparing gefitinib with carboplatin-paclitaxel for chemo-naïve non-small cell lung cancer with sensitive EGFR gene mutations (NEJ002)

BACKGROUND

NEJ002 study, comparing gefitinib with carboplatin (CBDCA) and paclitaxel (PTX; Taxol) as the first-line treatment for advanced non-small cell lung cancer (NSCLC) harboring an epidermal growth factor receptor (EGFR) mutation, previously reported superiority of gefitinib over CBDCA/PTX on progression-free survival (PFS). Subsequent analysis was carried out mainly regarding overall survival (OS).

MATERIALS AND METHODS

For all 228 patients in NEJ002, survival data were updated in December, 2010. Detailed information regarding subsequent chemotherapy after the protocol treatment was also assessed retrospectively and the impact of some key drugs on OS was evaluated.

RESULTS

The median survival time (MST) was 27.7 months for the gefitinib group, and was 26.6 months for the CBDCA/PTX group (HR, 0.887; P=0.483). The OS of patients who received platinum throughout their treatment (n=186) was not statistically different from that of patients who never received platinum (n=40). The MST of patients treated with gefitinib, platinum, and pemetrexed (PEM) or docetaxel (DOC, Taxotere; n=76) was around 3 years.

CONCLUSIONS

No significant difference in OS was observed between gefitinib and CBDCA/PTX in the NEJ002 study, probably due to a high crossover use of gefitinib in the CBDCA/PTX group. Considering the many benefits and the risk of missing an opportunity to use the most effective agent for EGFR-mutated NSCLC, the first-line gefitinib is strongly recommended.

Elucidation of the Erwinia uredovora carotenoid biosynthetic pathway by functional analysis of gene products expressed in Escherichia coli

The most important function of carotenoid pigments, especially beta-carotene in higher plants, is to protect organisms against photooxidative damage (G. Britton, in T. W. Goodwin, ed., Plant Pigments--1988, 1988; N. I. Krinsky, in O. Isler, H. Gutmann, and U. Solms, ed., Carotenoids--1971, 1971). beta-Carotene also functions as a precursor of vitamin A in mammals (G. A. J. Pitt, in I. Osler, H. Gutmann, and U. Solms, ed., Carotenoids--1971, 1971). The enzymes and genes which mediate the biosynthesis of cyclic carotenoids such as beta-carotene are virtually unknown. We have elucidated for the first time the pathway for biosynthesis of these carotenoids at the level of enzyme-catalyzed reactions, using bacterial carotenoid biosynthesis genes. These genes were cloned from a phytopathogenic bacterium, Erwinia uredovora 20D3 (ATCC 19321), in Escherichia coli and located on a 6,918-bp fragment whose nucleotide sequence was determined. Six open reading frames were found and designated the crtE, crtX, crtY, crtI, crtB, and crtZ genes in reference to the carotenoid biosynthesis genes of a photosynthetic bacterium, Rhodobacter capsulatus; only crtZ had the opposite orientation from the others. The carotenoid biosynthetic pathway in Erwinia uredovora was clarified by analyzing carotenoids accumulated in E. coli transformants in which some of these six genes were expressed, as follows: geranylgeranyl PPiCrtB----prephytoene PPiCrtE----phytoeneCrtI---- lycopeneCrtY----beta-caroteneCrtZ----zeaxanthinCrtX--- -zeaxanthin-beta- diglucoside. The carotenoids in this pathway appear to be close to those in higher plants rather than to those in bacteria. Also significant is that only one gene product (CrtI) for the conversion of phytoene to lycopene is required, a conversion in which four sequential desaturations should occur via the intermediates phytofluene, zeta-carotene, and neurosporene.

An ancient retrotransposal insertion causes Fukuyama-type congenital muscular dystrophy

Fukuyama-type congenital muscular dystrophy (FCMD), one of the most common autosomal recessive disorders in Japan (incidence is 0.7-1.2 per 10,000 births), is characterized by congenital muscular dystrophy associated with brain malformation (micropolygria) due to a defect in the migration of neurons. We previously mapped the FCMD gene to a region of less than 100 kilobases which included the marker locus D9S2107 on chromosome 9q31. We have also described a haplotype that is shared by more than 80% of FCMD chromosomes, indicating that most chromosomes bearing the FCMD mutation could be derived from a single ancestor. Here we report that there is a retrotransposal insertion of tandemly repeated sequences within this candidate-gene interval in all FCMD chromosomes carrying the founder haplotype (87%). The inserted sequence is about 3 kilobases long and is located in the 3' untranslated region of a gene encoding a new 461-amino-acid protein. This gene is expressed in various tissues in normal individuals, but not in FCMD patients who carry the insertion. Two independent point mutations confirm that mutation of this gene is responsible for FCMD. The predicted protein, which we term fukutin, contains an amino-terminal signal sequence, which together with results from transfection experiments suggests that fukutin is a secreted protein. To our knowledge, FCMD is the first human disease to be caused by an ancient retrotransposal integration.

Location of stem cells of human hair follicles by clonal analysis

We have examined the growth capacity of keratinocytes isolated from human scalp hair follicles. Like the keratinocytes of glabrous epidermis, most of the colony-forming cells are classified as holoclones or meroclones when analyzed in a clonal assay. Some of them have extensive growth potential, as they are able to undergo at least 130 doublings. Therefore, the hair follicle, like the epidermis, contains keratinocytes with the expected property of stem cells: an extensive proliferative capacity permitting the generation of a large amount of epithelium. We have also examined the distribution of clonogenic keratinocytes within the hair follicle. Several hundred colony-forming cells are concentrated at a region below the midpoint of the follicle and outside the hair bulb. This region lies deeper than the site of insertion of the arrector pili muscle, which corresponds with the position of the bulge when the latter can be identified. In contrast, few colony-forming cells are present in the hair bulb, where most of the mitotic activity is observed during the active growth phase of the follicle. Paraclones, which are present both in the midregion and in the bulb of hair follicles, are unlikely to be the transient amplifying cells expected from kinetic studies.

Citrin and aralar1 are Ca(2+)-stimulated aspartate/glutamate transporters in mitochondria

The mitochondrial aspartate/glutamate carrier catalyzes an important step in both the urea cycle and the aspartate/malate NADH shuttle. Citrin and aralar1 are homologous proteins belonging to the mitochondrial carrier family with EF-hand Ca(2+)-binding motifs in their N-terminal domains. Both proteins and their C-terminal domains were overexpressed in Escherichia coli, reconstituted into liposomes and shown to catalyze the electrogenic exchange of aspartate for glutamate and a H(+). Overexpression of the carriers in transfected human cells increased the activity of the malate/aspartate NADH shuttle. These results demonstrate that citrin and aralar1 are isoforms of the hitherto unidentified aspartate/glutamate carrier and explain why mutations in citrin cause type II citrullinemia in humans. The activity of citrin and aralar1 as aspartate/glutamate exchangers was stimulated by Ca(2+) on the external side of the inner mitochondrial membrane, where the Ca(2+)-binding domains of these proteins are localized. These results show that the aspartate/glutamate carrier is regulated by Ca(2+) through a mechanism independent of Ca(2+) entry into mitochondria, and suggest a novel mechanism of Ca(2+) regulation of the aspartate/malate shuttle.

Benign and malignant nodules in cirrhotic livers: distinction based on blood supply

The blood supplies of nodular lesions associated with liver cirrhosis were analyzed in vivo with various imaging modalities. The portal blood supply was evaluated with computed tomography (CT) during arterial portography (CTAP); the arterial blood supply was evaluated with hepatic angiography, CT angiography, CT following intraarterial injection of iodized oil, or ultrasound following intraarterial injection of carbon dioxide microbubbles. A total of 84 surgically confirmed hepatocellular carcinomas (HCCs) (less than or equal to 3 cm) and 25 areas of adenomatous hyperplasia (AH) were included in the study. At CTAP, a portal blood supply was seen in 96% of cases of AH and only 6% of HCCs (chi 2, P less than .005). In contrast, an arterial supply greater than that of the surrounding liver was verified in 94% of the HCCs and only 4% of the cases of AH (chi 2, P less than .005). The blood supply of areas of AH with atypical hepatocytes and the blood supply of well-differentiated HCCs (Edmondson grade 1) tended to be intermediate between that of AH without atypia and that of HCC that was Edmondson and Steiner grade 2 or greater. Evaluation of the blood supply of the nodular lesions associated with liver cirrhosis is considered to be useful in the differential diagnosis and treatment of early-stage HCC.

The gene mutated in adult-onset type II citrullinaemia encodes a putative mitochondrial carrier protein

Citrullinaemia (CTLN) is an autosomal recessive disease caused by deficiency of argininosuccinate synthetase (ASS). Adult-onset type II citrullinaemia (CTLN2) is characterized by a liver-specific ASS deficiency with no abnormalities in hepatic ASS mRNA or the gene ASS (refs 1-17). CTLN2 patients (1/100,000 in Japan) suffer from a disturbance of consciousness and coma, and most die with cerebral edema within a few years of onset. CTLN2 differs from classical citrullinaemia (CTLN1, OMIM 215700) in that CTLN1 is neonatal or infantile in onset, with ASS enzyme defects (in all tissues) arising due to mutations in ASS on chromosome 9q34 (refs 18-21). We collected 118 CTLN2 families, and localized the CTLN2 locus to chromosome 7q21.3 by homozygosity mapping analysis of individuals from 18 consanguineous unions. Using positional cloning we identified a novel gene, SLC25A13, and found five different DNA sequence alterations that account for mutations in all consanguineous patients examined. SLC25A13 encodes a 3.4-kb transcript expressed most abundantly in liver. The protein encoded by SLC25A13, named citrin, is bipartite in structure, containing a mitochondrial carrier motif and four EF-hand domains, suggesting it is a calcium-dependent mitochondrial solute transporter with a role in urea cycle function.

Impairment of hippocampal mossy fiber LTD in mice lacking mGluR2

Subtype 2 of the metabotropic glutamate receptor (mGluR2) is expressed in the presynaptic elements of hippocampal mossy fiber-CA3 synapses. Knockout mice deficient in mGluR2 showed no histological changes and no alterations in basal synaptic transmission, paired-pulse facilitation, or tetanus-induced long-term potentiation (LTP) at the mossy fiber-CA3 synapses. Long-term depression (LTD) induced by low-frequency stimulation, however, was almost fully abolished. The mutant mice performed normally in water maze learning tasks. Thus, the presynaptic mGluR2 is essential for inducing LTD at the mossy fiber-CA3 synapses, but this hippocampal LTD does not seem to be required for spatial learning.

Neuronal repair. Asynchronous therapy restores motor control by rewiring of the rat corticospinal tract after stroke

The brain exhibits limited capacity for spontaneous restoration of lost motor functions after stroke. Rehabilitation is the prevailing clinical approach to augment functional recovery, but the scientific basis is poorly understood. Here, we show nearly full recovery of skilled forelimb functions in rats with large strokes when a growth-promoting immunotherapy against a neurite growth-inhibitory protein was applied to boost the sprouting of new fibers, before stabilizing the newly formed circuits by intensive training. In contrast, early high-intensity training during the growth phase destroyed the effect and led to aberrant fiber patterns. Pharmacogenetic experiments identified a subset of corticospinal fibers originating in the intact half of the forebrain, side-switching in the spinal cord to newly innervate the impaired limb and restore skilled motor function.

Prospective study of early detection of hepatocellular carcinoma in patients with cirrhosis

We prospectively monitored 140 cirrhotic patients for the development of hepatocellular carcinoma for 6 yr, using periodical screening by high-resolution convex-array ultrasonography and alpha-fetoprotein. Twenty-eight patients were positive for HBs antigen, 26 patients had received blood transfusions and were negative for HBs antigen and 26 patients had a history of heavy drinking. We detected hepatocellular carcinoma in 40 patients during this period. The overall cumulative incidence of hepatocellular carcinoma in the 6 yr was 39%; the cumulative incidence was 59% in patients with HBsAg, 53% in patients who had had blood transfusions and were negative for HBsAg and 22% in patients who had a history of heavy drinking and who were without HBsAg. Detection of the carcinoma in 85% of these 40 patients was based on results of ultrasonography. Twenty-six of the patients (65%) had a small hepatocellular carcinoma of 2 cm or less. alpha-Fetoprotein levels were lower than 100 ng/ml in 56% of these 40 patients. Patients with cirrhosis are at high risk of developing hepatocellular carcinoma, especially patients with HBsAg or with a history of blood transfusion who are negative for HBsAg. Periodic monitoring by use of ultrasonography in particular is recommended for early detection of hepatocellular carcinoma.

Identification of IQGAP as a putative target for the small GTPases, Cdc42 and Rac1

Cdc42 and Rac1 have been implicated in the regulation of various cell functions such as cell morphology, polarity, and cell proliferation. We have partially purified a Cdc42- and Rac1-associated protein with molecular mass of about 170 kDa (p170) from bovine brain cytosol. This protein interacted with guanosine 5'-(3-O-thio)triphosphate (GTPgammaS).glutathione S-transferase (GST)-Cdc42 and GTPgammaS++.GST-Rac1 but not with the GDP.GST-Cdc42, GDP.GST-Rac1, or GTPgammaS.GST-RhoA). We identified p170 as an IQGAP, which is originally identified as a putative Ras GTPase-activating protein. Recombinant IQGAP specifically interacted with GTPgammaS.Cdc42 and GTPgammaS.Rac1. The C-terminal fragment of IQGAP was responsible for their interactions. IQGAP was specifically immunoprecipitated with dominant-active Cdc42(Val12) or Rac1(Val12) from the COS7 cells expressing Cdc42(Val12) or Rac1(Val12), respectively. Immunofluorescence analysis revealed that IQGAP was accumulated at insulin- or Rac1-induced membrane ruffling areas. This accumulation of IQGAP was blocked by the microinjection of the dominant-negative Rac1(Asn17) or Cdc42(Asn17). Moreover, IQGAP was accumulated at the cell-cell junction in MDCK cells, where alpha-catenin and ZO-1 were localized. These results suggest that IQGAP is a novel target molecule for Cdc42 and Rac1.

Giant Rashba-type spin splitting in bulk BiTeI

There has been increasing interest in phenomena emerging from relativistic electrons in a solid, which have a potential impact on spintronics and magnetoelectrics. One example is the Rashba effect, which lifts the electron-spin degeneracy as a consequence of spin-orbit interaction under broken inversion symmetry. A high-energy-scale Rashba spin splitting is highly desirable for enhancing the coupling between electron spins and electricity relevant for spintronic functions. Here we describe the finding of a huge spin-orbit interaction effect in a polar semiconductor composed of heavy elements, BiTeI, where the bulk carriers are ruled by large Rashba-like spin splitting. The band splitting and its spin polarization obtained by spin- and angle-resolved photoemission spectroscopy are well in accord with relativistic first-principles calculations, confirming that the spin splitting is indeed derived from bulk atomic configurations. Together with the feasibility of carrier-doping control, the giant-Rashba semiconductor BiTeI possesses excellent potential for application to various spin-dependent electronic functions.

Prospective study of alpha-fetoprotein in cirrhotic patients monitored for development of hepatocellular carcinoma

The usefulness of measurements of serum alpha-fetoprotein elevation for diagnosis of the development of hepatocellular carcinoma was evaluated by a prospective study of 260 patients with cirrhosis. Hepatocellular carcinoma was found in 55 patients during the 5-yr follow-up, excluding 7 found to have hepatocellular carcinoma in the first 6 mo. The cumulative incidence of hepatocellular carcinoma was 26% in the 185 patients who had alpha-fetoprotein levels below 20 ng/ml at the time of entry and 46% in the 68 patients who had alpha-fetoprotein levels of 20 ng/ml or more but below 200 ng/ml. In 169 of the patients, serum levels of alpha-fetoprotein were assayed regularly for at least 2 yr. The incidence of hepatocellular carcinoma development in the 36 patients who had repeated transient increases in alpha-fetoprotein to above 100 ng/ml was 36%. This was significantly higher than the incidence in the 99 patients who had alpha-fetoprotein levels consistently below 20 ng/ml. Thus patients who had alpha-fetoprotein levels of 20 ng/ml or more, who had transient increases in alpha-fetoprotein or who had both should be treated as being in a super-high-risk group for hepatocellular carcinoma. Frequent and careful examination by ultrasonography of such patients is recommended.