Enhanced silicon oxidation on titanium-covered Si(001)

We report on a core level photoemission study of the formation of an ultrathin SiO(x) layer grown at the interface of a titanium-covered Si(001) surface. Oxygen exposure at room temperature induces a large chemical shift of the Si 2p state, predominantly assigned to Si(4+). The results indicate that a SiO(2 - δ) layer, close to the stoichiometry of SiO(2), is formed below the TiO(x) film. The thickness of the SiO(2 - δ) layer is estimated to be ∼ 0.9 nm, corresponding to three to four oxide layers. Further chemical shift caused by annealing is attributed to the formation of titanium silicate (TiSi(x)O(y)).

New double embedding technique for specimens of endoscopic submucosal dissection using agarose: comparison with other media

AIMS

Procedure of endoscopic submucosal dissection (ESD) has been introduced widely for treatment of early gastric cancers. For such specimens, accurate pathological diagnosis, especially concerning depth of the invasion and exposure to margins, is essential to decide on the necessity of additional treatment. Therefore, easy and reliable tissue-processing method for multiple cut specimens is needed. The authors report here a new double embedding technique for specimens of ESD.

METHODS

Formalin-fixed whole specimen was superficially wrapped by agarose (the first embedding), and the tissue-agarose block was cut at 2-3 mm intervals. Each cut specimen was laid down with 90° rotation. This procedure permitted 'on edge' embedding of thin tissues in paraffin (the second embedding) and subsequent preparation of perpendicular section to the tissue surface. The authors compared the handleability and stainability among several media including various types of agar, agarose and gelatin for first embedding. A survey by questionnaire was carried out on handleability and/or impression on various tissue-processing steps from pathology technicians.

RESULTS

Among the media examined, agarose showed the best solubility in water and the best transparency on several representative stainings. According to the survey, pathology technicians seemed to feel that the present method was better than the usual tissue processing method, especially in shortened time consumption and accuracy of alignment of multiple tissues for ESD specimens.

CONCLUSIONS

The present new double embedding technique using agarose provides not only an easy and reliable embedding procedure for technicians but also accurate and exact diagnosis for pathologists.

Sequential arrival and graded secretion of Sema3F by olfactory neuron axons specify map topography at the bulb

In the mouse olfactory system, the anatomical locations of olfactory sensory neurons (OSNs) roughly correlate with their axonal projection sites along the dorsal-ventral (D-V) axis of the olfactory bulb (OB). Here we report that an axon guidance receptor, Neuropilin-2 (Nrp2), and its repulsive ligand, Semaphorin-3F (Sema3F), are expressed by OSNs in a complementary manner that is important for establishing olfactory map topography. Sema3F is secreted by early-arriving axons of OSNs and is deposited at the anterodorsal OB to repel Nrp2-positive axons that arrive later. Sequential arrival of OSN axons as well as the graded and complementary expression of Nrp2 and Sema3F by OSNs help to form the topographic order along the D-V axis.

In vivo effect of imatinib on progression of cecal GIST-like tumors in exon 17-type c-kit knock-in mice

Two families with a germline Asp820Tyr mutation at exon 17 of the c-kit gene and multiple gastrointestinal stromal tumors (GISTs) have been reported. Recently, we generated a knock-in mouse model of the family, and mice with KIT-Asp818Tyr corresponding to human KIT-Asp820Tyr showed a cecal GIST-like tumor. In this report, we examined the in vivo effect of imatinib on tumor progression in knock-in mice. Imatinib of 100 microg/g body weight was administered to heterozygous (KIT-Asp818Tyr/+) mice orally for 7, 14 and 28 days, and cecal tumors were dissected. Both macroscopic size and the measured volume of cecal tumors were not significantly reduced after a 7-, 14- and 28-day administration of imatinib when compared with those before imatinib administration. Cell proliferation was assessed by Ki-67 immunohistochemistry and the labeling index significantly decreased after imatinib administration, but the value of the index after imatinib was only about half compared with that before imatinib. Western blotting and real-time PCR revealed that KIT expression was almost equivalent, but KIT phosphorylation was significantly but not completely inhibited in tumor tissues after 7, 14 and 28 days of imatinib administration when compared with that before imatinib administration. Phosphorylation of Akt and Stat1 was accordingly inhibited after imatinib administration. Thus, imatinib seemed to inhibit in vivo tumor proliferation but not decrease tumor volume on this mouse model, probably because of an insufficient inhibition of phosphorylation of KIT and its downstream signaling molecules. These results suggested that progression of multiple GISTs in patients with germline Asp820Tyr might be partially controlled by imatinib and that model mice provide an opportunity to examine the effect of various other targeted drugs on in vivo tumor progression.

Solid-pseudopapillary neoplasm of the pancreas with massive central calcification in an old man

Solid-pseudopapillary neoplasm (SPN) is a rare pancreatic tumor primarily affecting women in their twenties. It is characterized by a well-demarcated or encapsulated mass, indolent behavior and favorable prognosis. Capsular or punctate calcification is occasionally observed. Reported herein is a case of SPN of the pancreas with massive calcification in a 76-year-old Japanese man. Macroscopically, the pancreatic tumor appeared to be a simple calcified nodule, but histological examination revealed that it was an epithelioid tumor with massive calcification. The tumor cells, forming nests and cords, had eosinophilic cytoplasm and small eccentric nuclei. They were immunohistochemically positive for vimentin, CD56 and neuron-specific enolase. Nuclear accumulation of beta-catenin protein and a point mutation of the beta-catenin gene by genomic DNA sequencing confirmed that the tumor was SPN. This is a very rare case of pancreatic SPN with massive calcification in an old man.

Mucinous Cystadenocarcinoma of the Colon during Pregnancy

A rare case of mucinous adenocarcinoma of the cecum in a pregnant woman is described. A 32-year-old Korean woman was diagnosed as having an abdominal tumor immediately after giving birth. Abdominal computed tomography demonstrated a smooth mass measuring 10 cm in diameter on the right side of the abdomen. Acute abdomen developed 3 days after birth. At emergency surgery, volvulus of a polypoid tumor was detected at the cecum apart from the normal appendix. We successfully performed a tumorectomy; however, histopathological examination demonstrated mucinous adenocarcinoma with a massive blood clot.

Generation of RGS8 null mutant mice by Cre/loxP system

Regulators of G-protein signaling (RGS) proteins are negative regulators of heterotrimeric guanine-nucleotide-binding proteins (G-proteins) by activating intrinsic GTPase activity of G alpha and thereby terminating G-protein coupled receptor-associated signal transduction. RGS8 belongs to B/R4 subfamily of RGS proteins and is expressed in the central nervous system, especially dense in cerebellar Purkinje cells. RGS8 binds specifically to G alpha o and G alpha i3 in vitro and activates their intrinsic GTPase activities. To investigate the role of RGS8 in vivo, we generated mice lacking RGS8 by gene targeting in embryonic stem (ES) cells using Cre/loxP system. RGS8 null mutant mice were viable, fertile and showed apparently normal development. Histological analysis showed no apparent abnormalities in morphology of cerebellar layer or Purkinje cells in RGS8 null mutant mice.

High-yield synthesis of conductive carbon nanotube tips for multiprobe scanning tunneling microscope

We have established a fabrication process for conductive carbon nanotube (CNT) tips for multiprobe scanning tunneling microscope (STM) with high yield. This was achieved, first, by attaching a CNT at the apex of a supporting W tip by a dielectrophoresis method, second, by reinforcing the adhesion between the CNT and the W tip by electron beam deposition of hydrocarbon and subsequent heating, and finally by wholly coating it with a thin metal layer by pulsed laser deposition. More than 90% of the CNT tips survived after long-distance transportation in air, indicating the practical durability of the CNT tips. The shape of the CNT tip did not change even after making contact with another metal tip more than 100 times repeatedly, which evidenced its mechanical robustness. We exploited the CNT tips for the electronic transport measurement by a four-terminal method in a multiprobe STM, in which the PtIr-coated CNT portion of the tip exhibited diffusive transport with a low resistivity of 1.8 kOmega/microm. The contact resistance at the junction between the CNT and the supporting W tip was estimated to be less than 0.7 kOmega. We confirmed that the PtIr thin layer remained at the CNT-W junction portion after excess current passed through, although the PtIr layer was peeled off on the CNT to aggregate into particles, which was likely due to electromigration or a thermally activated diffusion process. These results indicate that the CNT tips fabricated by our recipe possess high reliability and reproducibility sufficient for multiprobe STM measurements.

Role of spin-orbit coupling and hybridization effects in the electronic structure of ultrathin Bi films

The electronic structure of Bi(001) ultrathin films (thickness > or =7 bilayers) on Si(111)-7x7 was studied by angle-resolved photoemission spectroscopy and first-principles calculations. In contrast with the semimetallic nature of bulk Bi, both the experiment and theory demonstrate the metallic character of the films with the Fermi surface formed by spin-orbit-split surface states (SSs) showing little thickness dependence. Below the Fermi level, we clearly detected quantum well states (QWSs) at the M point, which were surprisingly found to be non-spin-orbit split; the films are "electronically symmetric" despite the obvious structural nonequivalence of the top and bottom interfaces. We found that the SSs hybridize with the QWSs near M and lose their spin-orbit-split character.

The distance from the skin to the epidural space

To determine whether there is any systemic relationship between the distance from the skin to the epidural space and physical constitution, the distance from the skin to the epidural space was measured in 1007 epidural punctures. The distance from the skin to the epidural space in male was greater than that in female ( P << 0.001). However, the analysis of the distance from the skin to the epidural space of the selected patients who had both a weight of 50-60 kg and a height of 1.5-1.7 m indicated no statistical difference between male and female. The best correlation was found between the distance from the skin to the epidural space and body weight. The correlation between the distance from the skin to the epidural space and height was less striking. Ninety-five percent of the patients who received epidural puncture at the thoraco-cervical area (C7-T2) had a distance to the epidural space of 4.0-6.9 cm; 87% at the lower-thoracic area (T8-T10), 4.0-6.9 cm; 93% at the thoraco-lumbar area (T12-L2), 3.0-4.9 cm; 85% at the mid-lumbar area (L2-L4), 3.0-4.9 cm. These results may be useful for young anesthesiologists to master epidural block safely and efficiently.

Receptor knock-out and knock-in strategies

Accumulating examples have demonstrated that knock-out and knock-in mice of G-protein-coupled receptors (GPCRs) are useful in elucidating physiological functions of the receptor in vivo. GPCR knock-out and knock-in are achieved by either (1) manipulation of the endogenous locus of the receptor gene or (2) transgenic expression of the modified receptor. Historically speaking, the first generation knock-outs made the best use of homologous recombination in embryonic stem (ES) cells and their totipotency to introduce the desired mutation into the endogenous receptor locus. In the second-generation knock-outs using the Cre/loxP system, the disruption of the receptor gene is cell-type specific or region-specific but is irreversible in principle. In contrast, transgenic expression in the receptor knock-out mice of the wild-type receptor protein under a tissue- and stage-specific promoter (conditional "rescue" of the receptor knock-out) can be easily applied to create "reversible" or "inducible" knock-out of the receptor. This is called the third generation knock-out. In the following sections, we introduce examples of the materials and methods based on our in vivo analyses of the metabotropic glutamate receptor-subtype 1 (mGluR1).

Rice stripe virus 23.9 K protein aggregates and forms inclusion bodies in cultured insect cells and virus-infected plant cells

The genome of Rice stripe virus (RSV, genus Tenuivirus) contains seven open reading frames (ORFs). Little is known about the products of four of these ORFs, including the 23.9 K protein encoded by the virus-sense ORF of RNA3. Western blotting revealed that the 23.9 K protein was synthesized in the host plant and also in the planthopper vector of RSV. Using a baculovirus vector, the 23.9 K protein was expressed, both unfused and fused with red-shifted green fluorescent protein, in Spodoptera frugiperda cells. Inclusion bodies were observed by light microscope in cells expressing fused or unfused proteins. Inclusion bodies in cells expressing the fused protein fluoresced under blue light. By immunoelectron microscopy, electron-dense inclusion bodies in cells expressing the unfused protein were specifically labeled with 23.9 K protein antiserum. Moreover, electron-dense masses labeled with 23.9 K protein antiserum were observed in virus-infected wheat tissue by electron microscopy. This paper thus demonstrates that RSV 23.9 K protein can aggregate in vivo and form inclusion bodies in infected plant tissue.

Prenatal genetic testing in Japan

OBJECTIVE

To examine the use of prenatal diagnosis and maternal serum marker tests (MSMTs) from January 1 to December 31, 1997, in Japan.

METHODS

Questionnaires were sent to medical facilities, which represent about 80% of the facilities providing prenatal diagnosis.

RESULTS

Prenatal diagnosis was performed in 5,748 women, of whom 5,538 (5,516 amniocenteses and 22 chorionic villus sampling; 96.3%) were screened for chromosomal abnormalities. 89.1% (221/248) of those diagnosed to have fetal abnormalities terminated the pregnancy. Written informed consent signed by both the obstetrician and the pregnant woman undergoing prenatal diagnosis was the policy in 76.5% facilities. A total of 14,682 MSMTs were performed: 8,919 were in pregnant women under 34 years of age and 5,763 were in women aged 35 years or older. Follow-up data were obtained in 10,209; 6,918 women under 34 years were tested; of those 448 had a positive result; 349 underwent amniocentesis and trisomy 21 was diagnosed in 9. 3,291 women aged 35 years or older were tested; of those 634 had a positive result; 607 underwent amniocentesis and trisomy 21 was found in 16 cases. Written informed consent before MSMTs was obtained in 34.5% of the facilities.

CONCLUSION

The data showed that only 4% of pregnant women above age 35 years underwent amniocentesis in Japan, and a small proportion of pregnant women were being offered MSMTs. Prenatal testing should be carried out only on a voluntary basis. For this purpose, women must be adequately informed.

Antimetastatic effect of hepatotropic liposomal adriamycin on human metastatic liver tumors

Adriamycin (ADM) was encapsulated in a galactose-conjugated hepatotropic liposome (hLip-ADM) and its ability to enhance the antitumor effect while reducing toxicity was compared with that of free ADM and a control Lip-ADM (cLip-ADM), in two in vitro animal models. Liver metastases were induced in rats by an intravenous injection of 8 x 10(6) AH-130 rat hepatoma tumor cells. All forms of the ADM completely inhibited liver metastasis when given at a dose of 5 mg/kg on day 14 after tumor implantation, whereas liver metastatic foci were observed in six of ten rats in the control group. The reduction in ADM toxicity by liposomalization was remarkable, as significant body weight loss was observed only in the free ADM group, in which four of ten rats died. Additional experiments utilized a human colon cancer xenograft (TK-4) to induce the growth of the liver metastases in mice by orthotopic implantation. The hLip-ADM completely inhibited liver metastasis in rats (0/11), whereas liver metastases developed in 10 of 12 mice in the control group and in 5 of 12 mice given cLip-ADM. Interestingly, liposomal ADM did not have a significant inhibitory effect on transplanted tumor growth assessed 6 weeks after transplantation. These findings indicate that hLip-ADM may be an effective strategy for inhibiting liver metastases from human colon cancer.

Congenital insensitivity to pain with anhidrosis (CIPA): novel mutations of the TRKA (NTRK1) gene, a putative uniparental disomy, and a linkage of the mutant TRKA and PKLR genes in a family with CIPA and pyruvate kinase deficiency

Congenital insensitivity to pain with anhidrosis is an autosomal recessive hereditary disorder characterized by recurrent episodic fever, anhidrosis (inability to sweat), absence of reaction to noxious stimuli, self-mutilating behavior, and mental retardation. The human TRKA gene (NTRK1), located on chromosome 1q21-q22 encodes the receptor tyrosine kinase for nerve growth factor. We reported that TRKA is the gene responsible for CIPA and we developed a comprehensive strategy to screen for TRKA mutations and polymorphisms, as based on the gene's structure and organization. Here we report eight novel mutations detected as either a homozygous or heterozygous state in nine CIPA families from five countries. Mendelian inheritance of the mutations was confirmed in seven families for which samples from either parent were available. However, non-mendelian inheritance seems likely for the family when only samples from the mother and siblings, (but not from the father) were available. A paternal uniparental disomy for chromosome 1 is likely to be the cause of reduction to homozygosity of the TRKA gene mutation in this family. Interestingly, a Hispanic patient from the USA has two autosomal genetic disorders, CIPA and pyruvate kinase deficiency, whose genetic loci are both mapped to a closely linked chromosomal region. A splice mutation and a missense mutation were detected in the TRKA and PKLR genes from the homozygous proband, respectively. Thus, concomitant occurrence of two disorders is ascribed to a combination of two separate mutant genes, not a contiguous gene syndrome. This finding suggests a mechanism responsible for two autosomal genetic disorders in one patient. All these data further support findings that TRKA defects can cause CIPA in various ethnic groups. This will aid in diagnosis and genetic counseling of this painless but severe genetic disorder.

Roles of the glutamate receptor epsilon2 and delta2 subunits in the potentiation and prepulse inhibition of the acoustic startle reflex

We examined the regulation of the acoustic startle response in mutant mice of the N-methyl-D-aspartate (NMDA)- and delta-subtypes of the glutamate receptor (GluR) channel, which play important roles in neural plasticity in the forebrain and the cerebellum, respectively. Heterozygous mutant mice with reduced GluRepsilon2 subunits of the NMDA receptor showed strongly enhanced startle responses to acoustic stimuli. On the other hand, heterozygous and homozygous mutation of the other NMDA receptor GluRepsilon subunits exerted no, or only small effects on acoustic startle responses. The threshold of the auditory brainstem response of the GluRepsilon2-mutant mice was comparable to that of the wild-type littermates. The primary circuit of the acoustic startle response is a relatively simple oligosynaptic pathway located in the lower brainstem, whilst the expression of GluRepsilon2 is restricted to the forebrain. We thus suggest that the NMDA receptor GluRepsilon2 subunit plays a role in the regulation of the startle reflex. Ablation of the cerebellar Purkinje cell-specific delta2 subunit of the GluR channel exerted little effect on the acoustic startle response but resulted in the enhancement of prepulse inhibition of the reflex. Because inhibition of the acoustic startle response by a weak prepulse is a measure of sensorimotor gating, the process by which an organism filters sensory information, these observations indicate the involvement of the cerebellum in the modulation of sensorimotor gating.