Radiation dosage reduction in general dental practice using digital intraoral radiographic systems

This report describes the radiation dosage reduction possible in the general dental practice with two CCD (charge-coupled device)-based intraoral radiographic systems: the RVG-S (Trophy Radiologie, Vincennes, France) and the Sens-A-Ray (Regam Medical Systems, Sundsvall, Sweden). Radiation dosages (air-kerma; Gy) necessary for obtaining clinically acceptable images were measured at the cone tip using an ionization chamber type 660-1 (Nuclear Associates, Victoreen, Inc., Carle Place, New York, USA). When the RVG-S was used with an Oramatic 70 (Trophy Radiologie) X-ray generator, dosages at the cone tip ranged from 322 to 612 microGy. These corresponded to 40-60% of the dosages necessary when using Ektaspeed dental X-ray film (Eastman Kodak, Rochester, New York, USA) with a Heliodent 70 (Siemens, Erlangen, Germany) X-ray generator. At 60 kVp, the Sens-A-Ray reduced the dosage in the order of 30% compared with Ektaspeed dental X-ray film. Reduction in radiation dosage is one of the benefits of digital intraoral radiographic systems in general dental clinics. The RVG-S provides greater dose savings than does the Sens-A-Ray.

Cloning, expression and regulation of the human S14 gene

The rat S14 gene has been a useful model to study carbohydrate and triiodothyronine (T3) regulation of hepatic gene expression. To gain insight into the regulation and function of the S14 gene, we isolated the human S14 gene and studied its sequence, tissue specific expression, and transcriptional regulation by glucose and T3. The deduced amino acid sequence of the human S14 protein is 78% identical to that of the rat. Northern blot analysis showed that the S14-mRNA is a single species in human liver and is not present in human brain or HepG2 cells. Transfection studies in primary hepatocytes revealed that transcription of the human S14 gene is regulated by glucose and T3 in a similar manner to that of the rat gene. However, in HepG2 cells, T3 and glucose did not affect the transcription of the human S14 gene. These observations suggest that the S14 gene is highly conserved in mammals and is similarly regulated by carbohydrate and T3 in vivo. More importantly, the function of the human S14 gene may be critical in lipid metabolism in human liver as the rat S14 gene is in rodents.

Effects of ethyl alpha-D-glucoside on skin barrier disruption

Daily treatments of skin in hairless mice with concentrates of rice wine, Japanese traditional alcohol, lowered transepidermal water loss levels compared to the controls on the 3rd day after ultraviolet B (UVB) irradiation. These findings indicate that the concentrates of rice wine suppress the murine skin barrier disruption caused by UVB. Ethyl alpha-D-glucoside (alpha-ethylglucoside), one of the peculiar components in rice wine, showed the same effect, whereas beta-ethylglucoside had no effect. In order to clarify the functions of alpha-ethylglucoside on murine skin, we examined the effects of this compound on the expression of some phenotypes in human keratinocytes in vitro. As a result, alpha-ethylglucoside as well as beta-ethylglucoside enhanced cell proliferation weakly, and the formation of cornified envelopes and differentiated type keratin (K1) in keratinocytes was accelerated by alpha-ethylglucoside but not by beta-ethylglucoside. From the results, we conclude that alpha-ethylglucoside enhanced the differentiation of keratinocytes, which might be related to reduced barrier disruption by UVB.

Host range phenotype induced by mutations in the internal ribosomal entry site of poliovirus RNA

Most poliovirus strains infect only primates. The host range (HR) of poliovirus is thought to be primarily determined by a cell surface molecule that functions as poliovirus receptor (PVR), since it has been shown that transgenic mice are made poliovirus sensitive by introducing the human PVR gene into the genome. The relative levels of neurovirulence of polioviruses tested in these transgenic mice were shown to correlate well with the levels tested in monkeys (H. Horie et al., J. Virol. 68:681-688, 1994). Mutants of the virulent Mahoney strain of poliovirus have been generated by disruption of nucleotides 128 to 134, at stem-loop II within the 5' noncoding region, and four of these mutants multiplicated well in human HeLa cells but poorly in mouse TgSVA cells that had been established from the kidney of the poliovirus-sensitive transgenic mouse. Neurovirulence tests using the two animal models revealed that these mutants were strongly attenuated only in tests with the mouse model and were therefore HR mutants. The virus infection cycle in TgSVA cells was restricted by an internal ribosomal entry site (IRES)-dependent initiation process of translation. Viral protein synthesis and the associated block of cellular protein synthesis were not observed in TgSVA cells infected with three of four HR mutants and was evident at only a low level in the remaining mutant. The mutant RNAs were functional in a cell-free protein synthesis system from HeLa cells but not in those from TgSVA and mouse neuroblastoma NS20Y cells. These results suggest that host factor(s) affecting IRES-dependent translation of poliovirus differ between human and mouse cells and that the mutant IRES constructs detect species differences in such host factor(s). The IRES could potentially be a host range determinant for poliovirus infection.

Soluble thrombopoietin receptor (Mpl) and granulocyte colony-stimulating factor receptor directly stimulate proliferation of primitive hematopoietic progenitors of mice in synergy with steel factor or the ligand for Flt3/Flk2

In an effort to establish the specificity of the thrombopoietin (TPO) effects on murine multipotential progenitors, we tested the effects of soluble TPO receptor (sTPOR; sMpl) on multilineage colony formation that was supported by a combination of TPO and steel factor (SF). Surprisingly, sTPOR did not suppress colony formation from primitive progenitors. This led to the discovery that sTPOR synergizes with SF or Flt3/Flk2 ligand (FL) to support the formation of various types of hematopoietic colonies including multilineage colonies. The colonies supported by the combination of sTPOR and SF were capable of expressing both myeloid and B-lymphoid potentials. Studies using micromanipulation and serum-free culture showed that the effects of sTPOR and SF on the primitive progenitors are direct, not mediated by contaminating stromal cells, and not dependent on factors present in the serum. TPOR belongs to the cytokine receptor group that includes granulocyte colony-stimulating factor receptor (G-CSFR) and erythropoietin receptor (EPOR). Therefore, we tested the effects of sG-CSFR and sEPOR on primitive progenitors. sG-CSFR, but not sEPOR, was able to synergize with SF or FL in supporting the proliferation of primitive progenitors. The direct effects of the soluble receptors appear to be mediated through interactions with their respective membrane-bound receptors expressed on the primitive hematopoietic progenitors.

[Investigation of "anosmic zones" associated with nasal allergy]

Twenty-seven nasal allergy patients suffering from olfactory disturbance were evaluated in this study. The intravenous olfaction test yielded almost normal responses in 27 cases. The standard olfactory acuity test, however, showed that the mean thresholds of detection of each odor were almost the same, while the mean thresholds of recognition of odors A and E were higher than those of the other odors. Douek has reported selective olfactory loss in patients with vasomotor rhinitis including allergic rhinitis and proposed the concept of "anosmic zones". By modifying the definition of "anosmic zones" in order to use it for the results of T & T olfactometry, we identified 8 patients who exhibited anosmic zones among 27 subjects. These results were inconsistent with the proposed mechanism that nasal obstruction causes olfactory disturbance in patients suffering from nasal allergy. Therefore, the specific factors related to nasal allergy may influence olfaction. We speculate that the pathological changes in the olfactory mucosa may induce secondary abnormalities in olfactory transduction, particularly at the point of signal transduction in olfactory cells. Other possibilities to explain anosmic zones were also discussed.

Deficiencies of automatic endoscopic reprocessors: a method to achieve high-grade disinfection of endoscopes

BACKGROUND

We show that disinfection using the automatic endoscopic reprocessor is not complete and propose a method for high-grade disinfection of endoscopes.

METHODS

We used an automatic endoscopic reprocessor, Pyser System 83, and 2% glutaraldehyde. After each endoscopic procedure, the endoscopes were divided into three groups. Endoscopes in group A were washed only by the reprocessor. Group B endoscopes were washed by the reprocessor after the connectors were soaked in glutaraldehyde for 5 minutes. The channels, valves, connecting sections of group C endoscopes, and the connectors of the machine were sprayed with glutaraldehyde before machine-washing. Swabs were taken from all 13 parts of each endoscope and machine for microbiologic culture.

RESULTS

Six endoscopes were positive, cumulatively, for bacterial contamination in group A. Among group B endoscopes, one remained contaminated. No endoscope was positive in group C. The difference between group A and C was statistically significant (p < .05).

CONCLUSIONS

Machine washing by automatic endoscopic reprocessors may not achieve complete disinfection. Additional procedures are necessary. High-grade disinfection of the connectors is critical. Disinfection of the interface between the connectors is important.

Characterization of Cbl tyrosine phosphorylation and a Cbl-Syk complex in RBL-2H3 cells

Tyrosine phosphorylation of the Cbl protooncogene has been shown to occur after engagement of a number of different receptors on hematopoietic cells. However, the mechanisms by which these receptors induce Cbl tyrosine phosphorylation are poorly understood. Here we demonstrate that engagement of the high affinity IgE receptor (Fc epsilon R1) leads to the tyrosine phosphorylation of Cbl and analyze how this occurs. We show that at least part of Fc epsilon R1-induced Cbl tyrosine phosphorylation is mediated by the Syk tyrosine kinase, and that the Syk-dependent tyrosine phosphorylation of Cbl occurs mainly distal to the Cbl proline-rich region within the COOH-terminal 250 amino acids. Furthermore, we show by coprecipitation that Cbl is present in a complex with Syk before receptor engagement, that the proline-rich region of Cbl and a region of Syk comprised of the two SH2 domains and intradomain linker are required for formation of the complex, and that little or no tyrosine-phosphorylated Cbl is detected in complex with Syk. Overexpression of truncation mutants of Cbl capable of binding Syk has the effect of blocking tyrosine phosphorylation of endogenous Cbl. These results define a potentially important intramolecular interaction in mast cells and suggest a complex function for Cbl in intracellular signaling pathways.

Regulation of the association of p120cbl with Grb2 in Jurkat T cells

The c-cbl protooncogene product (p120(cbl)) is a known substrate of multiple tyrosine kinases. It is found in complexes with critical signal transduction molecules, including the linker protein Grb2. Here, we demonstrate using an immobilized Grb2-binding peptide that the Grb2-p120(cbl) complex dissociates in vivo following engagement of the T-cell antigen receptor in Jurkat T-cells. The early kinetics of this dissociation correlate with the known time course of tyrosine phosphorylation of p120(cbl) and other substrates. This dissociation persists in vivo even when p120(cbl) becomes dephosphorylated to basal levels. However, this decreased association is not observed in protein overlay assays on nitrocellulose membranes in which a Grb2 fusion protein is used to detect p120(cbl) from stimulated or unstimulated cells. These data suggest that the tyrosine phosphorylation of p120(cbl) does not completely account for the regulation of its association with Grb2. Additionally, we used truncation mutations of p120(cbl) to map the p120(cbl)-Grb2 interaction to amino acids 481-528 of p120(cbl); this interaction is stronger in longer constructs that include additional proline-rich motifs. The in vivo regulation of the Grb2-p120(cbl) complex further supports the idea of a significant role for p120(cbl) in receptor-mediated signaling pathways.

Myocardial adaptive changes and damage in ischemic heart disease

Changes in two of the elements of myocardial subcellular organelles relating to cardiac energetics, ventricular myosin isozymes and mitochondrial DNA mutations, were examined using left ventricular tissue samples obtained at autopsy from patients with ischemic heart disease. Myosin isozymes were examined in tissues from nine patients with ischemic heart disease and 12 control patients with cancer but no heart disease. Extracted myosin was separated by pyrophosphate gel electrophoresis. The relative concentration of each component was determined by densitometry. Mitochondrial DNA mutations were evaluated in tissues from ten patients with myocardial infarction and 11 control patients with cancer but no heart disease. DNA was extracted and mitochondrial DNA mutations were detected by the polymerase chain reaction. Two bands were revealed by pyrophosphate gel electrophoresis. These contained VM-A, which exhibited faster electrophoretic mobility and was present in lower concentrations, and VM-B, which had a lower mobility and a higher concentration, respectively. SDS polyacrylamide gel electrophoresis showed that these two components contained the heavy chain and light chains 1 and 2 of myosin. VM-A concentrations tended to be higher in patients with ischemic heart disease than in controls. A 7.4-kb deletion was detected between the D-loop and the ATPase 6 genes of mitochondrial DNA from the myocardium of 6 out of 10 patients with myocardial infarction. The relative amounts of the two myosin isozymes could be altered by ischemic heart disease, although the functional significance of these components is unclear. The changes in the two myosin isozymes might be an adaptive change to disordered energy metabolism, but this change was small. The myocardial mitochondrial DNA deletions in patients with myocardial infarction were thought to result from ischemic damage.

[Changes with aging in ECochG]

The present study was designed to determine the standard values of AP, adapted AP and CM (0.5, 1, 2, and 4kHz) of the electrocochleogram using subjects with normal hearing (20 ears, mean subject age 30.4 years). The input-output function, the latency and the threshold were measured in AP, whereas only an input-output curve was made for the adapted AP and the input-output function and the threshold were measused in CM. The CM threshold had the highest positive correlation with the threshold of the conventional pure tone audiometry at 1kHz. These standard curves will be very useful for analysing clinical data. In order to discuss the aging changes affecting electrocochleograms, the test subjects were divided into two groups, i.e. one group was composed of subjects under 30 years of age (mean: 19.7 y/o, 10 ears) and the other of those 30 years old or over (mean: 41.1y/o, 10 ears). There were no differences in hearing threshold or the threshold of the electrocochleogram between the two groups. The CM threshold exhibited the highest positive correlation with the threshold of conventional audiometry at 1kHz in both groups. AP and adapted AP showed no difference in any item between the two groups. Although there was no difference in the CM threshold, there was an obvious difference in the CM input-output curves between these two groups at high stimulus intensities of 2 and 4kHz. It is known that the EP decrement makes CM smaller. However, it is unlikely that this decreased CM response in the older group was due to EP suppression, since this phenomenon was only observed in response to high intensity stimulo and there was no difference in responses to low intensity stimulo. Another possible explanation for this phenomenon is aging changes in the basilar membrane, tectorial membrane and hair cells. Further studies are necessary to elucidate the etiology of the CM suppression revealed in the present study.

Distribution of inflammation and atrophy in the stomach of Helicobacter pylori-positive and -negative patients with chronic gastritis

OBJECTIVES

To investigate the extent of inflammation and atrophy in the stomach of Helicobacter pylori-positive and -negative patients with chronic gastritis.

METHODS

Endoscopy with biopsies from the lesser curvatures of the antrum, angulus, middle body, and the greater curvature of the middle body of the stomach was performed in 59 patients with histologically confirmed chronic gastritis. The extent of atrophic gastritis was assessed endoscopically as well histologically. H. pylori status was assessed by histology as well as enzyme-linked immunosorbent assay. The histological severity of chronic and acute inflammation, glandular atrophy, and intestinal metaplasia was assessed according to the Sydney system.

RESULTS

In H. pylori-positive patients, H. pylori was evenly distributed throughout the stomach when the extent of atrophic gastritis was limited to the antrum and the lesser curvature of the body, but disappeared from the antrum of patients with more extensive atrophic gastritis. The severity of acute and chronic inflammation at the greater curvature of the body increased with the extension of atrophic gastritis. In H. pylori-negative patients, the severity of chronic inflammation at the greater curvature of the body was significantly higher in patients with extensive atrophic gastritis than in those with a lesser extent of atrophic gastritis.

CONCLUSION

At the greater curvature of the body, the development of atrophy is closely associated with the increase in the severity of inflammation, which is more marked in H. pylori-positive patients.

Mitochondrial DNA mutations associated with the 11778 mutation in Leber's disease

To clarify the characteristics of possible synergestic mitochondrial DNA (mtDNA) mutations associated with Leber's hereditary optic neuropathy (LHON), we analyzed the entire nucleotide sequences of mitochondrial genome of two Japanese patients from independent pedigrees harboring the 11778 mtDNA mutation, and compared their sequences with those of 47 disease and 6 normal controls. We have detected several unique mutations in the mtDNA in addition to the 11778 mutation. Two nucleotide substitutions, an A-to-G transition at position 856 in the 12S rRNA gene and an A-to-G transition at 14692 in the T psi C loop of the tRNA(Glu) gene, occurred at highly conserved sites among various species. These mutations in combination with the 11778 mutation might synergetically contribute to the pathogenesis of LHON.

The extracellular region of granulocyte colony-stimulating factor receptor in solution has multiple oligomerization states without ligand

Expression and purification of the extracellular portion of granulocyte colony-stimulating factor (G-CSF) receptor, which contains an immunoglobulin-like (Ig) domain and the cytokine receptor homologous (CRH) region, using a baculovirus secretion system have shown that a tetrameric Ig-CRH protein (about 200 kDa) existed in addition to the dimer (85 kDa) [7]. Scatchard analysis revealed that the tetramer had ligand binding affinity, with a dissociation constant of about 2.5 nM. The tetramer dissociated into monomers at pH 2 and was re-formed at pH7, in contrast, the dimer was re-dimerized with the same treatment. These observations led us to hypothesize the existence of conformational heterogeneity, which leads to tetramer as well as dimer formation, in the soluble state of the Ig-CRH protein.

Formation of 1:1 complex of the cytokine receptor homologous region of granulocyte colony-stimulating factor receptor with ligand

The cytokine receptor homologous (CRH) region of the murine granulocyte colony-stimulating factor (G-CSF) receptor was secreted using a Escherichia coli maltose binding protein (MBP) fusion system. The CRH region was prepared from the periplasmic fraction by G-CSF affinity column chromatography and restriction protease factor Xa digestion, and was purified to homogeneity. The purified CRH region specifically bound G-CSF, with an apparent dissociation constant (kd) of about 1.5 x 10(-9) M. A 1:1 CRH.G-CSF complex was established by gel-filtration high pressure liquid chromatography (HPLC). However, a 2:1 stoichiometric complex was not established, as in the case of the growth hormone (GH) receptor [Recent Prog. Hormone Res., 48, 233-275 (1993)].

Ligand binding characteristics of the carboxyl-terminal domain of the cytokine receptor homologous region of the granulocyte colony-stimulating factor receptor

The carboxyl-terminal domain (BC domain, roughly 100 amino acid residues) of the cytokine receptor homologous region in the receptor for murine granulocyte colony-stimulating factor was secreted as a maltose binding protein fusion into the Escherichia coli periplasm. The murine BC domain was prepared from the fusion protein by restriction protease factor Xa digestion and was purified to homogeneity. The purified BC domain specifically and stoichiometrically bound granulocyte colony-stimulating factor. This result indicates that the BC domain is also critical for ligand binding, as shown for the amino-terminal domain of the cytokine receptor homologous region (Hiraoka, O., Anaguchi, H., Yamasaki, K., Fukunaga, R., Nagata, S., and Ota, Y. (1994) J. Biol. Chem. 269, 22412-22419). The tertiary folding and the beta-sheet structure of the BC domain were confirmed by NMR spectroscopy. The disulfide bond pattern suggested from peptide mapping was Cys224-Cys271 and Cys242-Cys285. Disruption of the disulfide bonds suggested that both bonds are critical for maintaining the folding of the BC domain, although a BC domain lacking the second bond still retained ligand binding activity. Mutational analysis of the WSXWS sequence conserved in the cytokine receptor family suggested that this motif is critical for protein folding rather than for ligand binding.

Requirement for the immunoglobulin-like domain of granulocyte colony-stimulating factor receptor in formation of a 2:1 receptor-ligand complex

The extracellular portion of the granulocyte colony-stimulating factor (G-CSF) receptor has a mosaic structure of six domains (each approximately 100 amino acid residues) consisting of an immunoglobulin-like (Ig) domain, a cytokine receptor homologous region subdivided into amino-terminal (BN) and carboxyl-terminal (BC) domains, and three fibronectin type III repeats. In the present study, we expressed the Ig-BN and the BN-BC regions and purified them to homogeneity as monomers using G-CSF affinity column chromatography. Using gel filtration high performance liquid chromatography, we investigated the molecular composition of receptor-ligand complexes formed between G-CSF and purified BN-BC or Ig-BN domains. In contrast to the well characterized example of the human growth hormone (GH) receptor, in which the BN-BC.GH complex shows a 2:1 receptor-ligand complex stoichiometry, the BN-BC domain of the G-CSF receptor formed a 1:1 complex. The isolated Ig-BN domain also formed a 1:1 complex with G-CSF. However, in the presence of both Ig-BN and BN-BC domains, we detected a 1:1:1 Ig-BN.G-CSF.BN-BC complex corresponding to the 2:1 receptor: ligand stoichiometry. These results suggest that 1) the Ig domain and both the BN and the BC domains are required for oligomerization of the G-CSF receptor, 2) G-CSF contains two binding sites for its receptor, and 3) there are two ligand binding sites on the G-CSF receptor, one site on the BN-BC domain and one on the Ig-BN domain.

Convenient desktop-scale production of the extracellular domain of the human growth hormone receptor by an insect-baculovirus secretion system using a protein-free culture

Expression of a gene encoding the extracellular domain of the human growth hormone receptor (hGHR-ED) inserted into the genome of Autographa californica nuclear polyhedrosis virus was done using a desktop-scale spinner culture. Spodoptera frugiperda 9 (Sf9) cells infected with the recombinant virus secreted a protein with hGH-binding activity into the medium. Oxygen supplementation was required for high level secretion of the product. The highest cell production capability was estimated at more than 15 mg hGHR-ED/liter of culture. A protein-free medium supported the production similar to that obtained in traditional serum-containing media. This spinner culture system is simple to operate, and does not require expert knowledge of culture techniques.

[Anomalous origin of the right pulmonary artery from the ascending aorta: a case report]

We report a successful case of anomalous origin of the right pulmonary artery from the ascending aorta. A 34 days old infant, who had suffered from cardiogenic shock, underwent a direct anastomosis of the right pulmonary artery to the main pulmonary artery behind the ascending aorta under cardiopulmonary bypass. Postoperative catheterization showed no significant stenosis over the anastomosis and normalized pulmonary artery pressure. We conclude that early surgical correction is necessary in the treatment of this life threatening disease.