Structural analyses of the GI.4 norovirus by cryo-electron microscopy and X-ray crystallography revealing binding sites for human monoclonal antibodies

Noroviruses are major causative agents of acute nonbacterial gastroenteritis in humans. There are neither antiviral therapeutic agents nor vaccines for noroviruses at this time. To evaluate the potential usefulness of two previously isolated human monoclonal antibody fragments, CV-1A1 and CV-2F5, we first conducted a single-particle analysis to determine the cryo-electron microscopy structure of virus-like particles (VLPs) from the genogroup I genotype 4 (GI.4) Chiba strain uniformly coated with CV-1A1 fragments. The results revealed that the GI.4-specific CV-1A1 antibody bound to the P2 subdomain, in which amino acids are less conserved and variable. Interestingly, a part of the CV-1A1 intrudes into the histo-blood group antigen-binding site, suggesting that this antibody might exert neutralizing activity. Next, we determined the crystal structure of the protruding (P) domain of the capsid protein in the complex form with the CV-2F5 antibody fragment. Consistent with the cross-reactivity, the CV-2F5 bound to the P1 subdomain, which is rich in amino acids conserved among the GI strains, and moreover induced a disruption of Chiba VLPs. These results suggest that the broadly reactive CV-2F5 antibody can be used as both a universal detection reagent and an antiviral drug for GI noroviruses.

IMPORTANCE

We conducted the structural analyses of the VP1 protein from the GI.4 Chiba norovirus to identify the binding sites of the previously isolated human monoclonal antibodies CV-1A1 and CV-2F5. The cryo-electron microscopy of the Chiba virus-like particles (VLPs) complexed with the Fv-clasp forms of GI.4-specific CV-1A1 revealed that this antibody binds to the highly variable P2 subdomain, suggesting that this antibody may have neutralizing ability against the GI.4 strains. X-ray crystallography revealed that the CV-2F5 antibody bound to the P1 subdomain, which is rich in conserved amino acids. This result is consistent with the ability of the CV-2F5 antibody to react with a wide variety of GI norovirus strains. It is also found that the CV-2F5 antibody caused a disruption of VLPs. Our findings, together with previous reports on the structures of VP1 proteins and VLPs, are expected to open a path for the structure-based development of antivirals and vaccines against norovirus disease.

Structural basis for the dual GTPase specificity of the DOCK10 guanine nucleotide exchange factor

Dedicator of cytokinesis 10 (DOCK10), an evolutionarily conserved guanine nucleotide exchange factor (GEF) for Rho GTPases, has the unique specificity within the DOCK-D subfamily to activate both Cdc42 and Rac, but the structural bases for these activities remained unknown. Here we present the crystal structures of the catalytic DHR2 domain of mouse DOCK10, complexed with either Cdc42 or Rac1. The structures revealed that DOCK10DHR2 binds to Cdc42 or Rac1 by slightly changing the arrangement of its two catalytic lobes. DOCK10 also has a flexible binding pocket for the 56th GTPase residue, allowing a novel interaction with Trp56Rac1. The conserved residues in switch 1 of Cdc42 and Rac1 showed common interactions with the unique Lys-His sequence in the β5/β6 loop of DOCK10DHR2. However, the interaction of switch 1 in Rac1 was less stable than that of switch 1 in Cdc42, due to amino acid differences at positions 27 and 30. Structure-based mutagenesis identified the DOCK10 residues that determine the Cdc42/Rac1 dual specificity.

Targeting Ras-binding domain of ELMO1 by computational nanobody design

The control of cell movement through manipulation of cytoskeletal structure has therapeutic prospects notably in the development of novel anti-metastatic drugs. In this study, we determine the structure of Ras-binding domain (RBD) of ELMO1, a protein involved in cytoskeletal regulation, both alone and in complex with the activator RhoG and verify its targetability through computational nanobody design. Using our dock-and-design approach optimized with native-like initial pose selection, we obtain Nb01, a detectable binder from scratch in the first-round design. An affinity maturation step guided by structure-activity relationship at the interface generates 23 Nb01 sequence variants and 17 of them show enhanced binding to ELMO1-RBD and are modeled to form major spatial overlaps with RhoG. The best binder, Nb29, inhibited ELMO1-RBD/RhoG interaction. Molecular dynamics simulation of the flexibility of CDR2 and CDR3 of Nb29 reveal the design of stabilizing mutations at the CDR-framework junctions potentially confers the affinity enhancement.

Crystal structure of human acetylcholinesterase in complex with tacrine: Implications for drug discovery

Alzheimer's disease (AD) is one of the most common, progressive neurodegenerative disorders affecting the aged populations. Though various disease pathologies have been suggested for AD, the impairment of the cholinergic system is one of the critical factors for the disease progression. Restoration of the cholinergic transmission through acetylcholinesterase (AChE) inhibitors is a promising disease modifying therapy. Being the first marketed drug for AD, tacrine reversibly inhibits AChE and thereby slows the breakdown of the chemical messenger acetylcholine (ACh) in the brain. However, the atomic level of interactions of tacrine towards human AChE (hAChE) is unknown for years. Hence, in the current study, we report the X-ray structure of hAChE-tacrine complex at 2.85 Å resolution. The conformational heterogeneity of tacrine within the electron density was addressed with the help of molecular mechanics assisted methods and the low-energy ligand configuration is reported, which provides a mechanistic explanation for the high binding affinity of tacrine towards AChE. Additionally, structural comparison of reported hAChE structures sheds light on the conformational selection and induced fit effects of various active site residues upon binding to different ligands and provides insight for future drug design campaigns against AD where AChE is a drug target.

Structural insights into the small GTPase specificity of the DOCK guanine nucleotide exchange factors

The dedicator of cytokinesis (DOCK) family of guanine nucleotide exchange factors (GEFs) regulates cytoskeletal dynamics by activating the GTPases Rac and/or Cdc42. Eleven human DOCK proteins play various important roles in developmental processes and the immune system. Of these, DOCK1-5 proteins bind to engulfment and cell motility (ELMO) proteins to perform their physiological functions. Recent structural studies have greatly enhanced our understanding of the complex and diverse mechanisms of DOCK GEF activity and GTPase recognition and its regulation by ELMO. This review is focused on gaining structural insights into the substrate specificity of the DOCK GEFs, and discuss how Rac and Cdc42 are specifically recognized by the catalytic DHR-2 and surrounding domains of DOCK or binding partners.

Piperidine-4-carboxamide as a new scaffold for designing secretory glutaminyl cyclase inhibitors

Alzheimer's disease (AD), a common chronic neurodegenerative disease, has become a major public health concern. Despite years of research, therapeutics for AD are limited. Overexpression of secretory glutaminyl cyclase (sQC) in AD brain leads to the formation of a highly neurotoxic pyroglutamate variant of amyloid beta, pGlu-Aβ, which acts as a potential seed for the aggregation of full length Aβ. Preventing the formation of pGlu-Aβ through inhibition of sQC has become an attractive disease-modifying therapy in AD. In this current study, through a pharmacophore assisted high throughput virtual screening, we report a novel sQC inhibitor (Cpd-41) with a piperidine-4-carboxamide moiety (IC₅₀ = 34 μM). Systematic molecular docking, MD simulations and X-ray crystallographic analysis provided atomistic details of the binding of Cpd-41 in the active site of sQC. The unique mode of binding and moderate toxicity of Cpd-41 make this molecule an attractive candidate for designing high affinity sQC inhibitors.

Structural Basis for the Dual Substrate Specificity of DOCK7 Guanine Nucleotide Exchange Factor

The Dedicator Of CytoKinesis (DOCK) family of atypical guanine nucleotide exchange factors activates the Rho family GTPases Rac and/or Cdc42 through DOCK homology region 2 (DHR-2). Previous structural analyses of the DHR-2 domains of DOCK2 and DOCK9 have shown that they preferentially bind Rac1 and Cdc42, respectively; however, the molecular mechanism by which DHR-2 distinguishes between these GTPases is unclear. Here we report the crystal structure of the Cdc42-bound form of the DOCK7 DHR-2 domain showing dual specificity for Rac1 and Cdc42. The structure revealed increased substrate tolerance of DOCK7 at the interfaces with switch 1 and residue 56 of Cdc42. Furthermore, molecular dynamics simulations showed a closed-to-open conformational change in the DOCK7 DHR-2 domain between the Cdc42- and Rac1-bound states by lobe B displacement. Our results suggest that lobe B acts as a sensor for identifying different switch 1 conformations and explain how DOCK7 recognizes both Rac1 and Cdc42.

Factors related to dissociation between objective and subjective masticatory function in Japanese community-dwelling elderly adults

Clinicians' evaluations of older adults sometimes reveal inconsistencies between objective and subjective dental status. This study investigated which factors contribute both to good objective masticatory function (OMF) and the poor subjective masticatory function (SMF) that often becomes a clinical issue. Study participants included 635 elderly community-dwelling Japanese adults who underwent a comprehensive geriatric health examination in 2012. SMF was assessed with a question from the Kihon Checklist on eating difficulties (poor or good). OMF was assessed by a colour-changing gum (poor or good). Also investigated were age, sex, depressive symptoms, instrumental activities of daily living (I-ADLs), number of people who joined the participant at dinner, grip strength, usual walking speed, number of remaining teeth, number of functional teeth and their occlusal force. The group with good OMF and good SMF, defined as group 1, and the group with good OMF but poor SMF, group 2, were compared. Logistic regression analyses confirmed that the number of remaining and functional teeth participants had was statistically unrelated to differences between OMF and SMF. Instead, differences were related to stronger depressive symptoms (OR = 1.67, CI = 1.14-2.44), less ability to conduct I-ADL activities (OR = 0.73, CI = 0.59-0.91), slower usual walking speeds (OR = 0.18, CI = 0.06-0.58) and less occlusal force (OR = 0.99, CI = 0.99-1.00). Depressive symptoms, I-ADLs, and physical function are shown to be significantly related to divergence between objective and subjective masticatory function in elderly Japanese. This suggests that dissociations between objective and subjective dental evaluations of elderly adults indicate need for assessment of their mental and physical function.

Frailty Severity and Dietary Variety in Japanese Older Persons: A Cross-Sectional Study

Providing older person individuals with an appropriate intervention at the time of frailty onset is important to prevent the progression of the condition and the need for long-term care. However, the proper timing of starting nutritional and dietary interventions for frail older person subjects has not been fully elucidated. Therefore, in this cross-sectional study, we aimed to clarify the association between frailty and dietary variety among older persons in Japan. We surveyed sex, age, body height, body weight, body mass index, serum albumin level, dietary variety, and nutritional intake indexes in 747 community-dwelling older person individuals who underwent a comprehensive health examination in October 2014. Frailty was determined using the Kihon Checklist (25 questions). Kihon Checklist is widely used to assess frailty in Japan, and their physical, cognitive and social function was evaluated. After excluding those who did not complete the Kihon Checklist and those who required long-term care, frailty status was analyzed in 665 older person individuals. The numbers and percentages of frail, pre-frail and robust older persons were found to be 77 (11.6%), 182 (27.4%) and 406 (61.0%) respectively. Significant differences among robust, pre-frail, and frail subjects were observed in terms of age, serum albumin level, alcohol consumption, smoking, and history of diabetes. Among the nutrition-related indexes, only the dietary variety showed a significant difference. The results of ordinal logistic regression analysis showed a significant association between frailty and sex, age, smoking status, diabetes, and dietary variety score. Dietary variety was significantly associated with the progression of frailty among older persons in the community.

FUT2 non-secretor status is associated with Type 1 diabetes susceptibility in Japanese children

AIM

To examine the contribution of the FUT2 gene and ABO blood type to the development of Type 1 diabetes in Japanese children.

METHODS

We analysed FUT2 variants and ABO genotypes in a total of 531 Japanese children diagnosed with Type 1 diabetes and 448 control subjects. The possible association of FUT2 variants and ABO genotypes with the onset of Type 1 diabetes was statistically examined.

RESULTS

The se2 genotype (c.385A>T) of the FUT2 gene was found to confer susceptibility to Type 1A diabetes in a recessive effects model [odds ratio for se2/se2, 1.68 (95% CI 1.20-2.35); corrected P value = 0.0075].

CONCLUSIONS

The FUT2 gene contributed to the development of Type 1 diabetes in the present cohort of Japanese children.

Relationship between Sensory Perception and Frailty in a Community-Dwelling Elderly Population

BACKGROUND

Aging anorexia, defined as loss of appetite and/or reduced food intake, has been postulated as a risk factor for frailty. Impairments of taste and smell perception in elderly people can lead to reduced enjoyment of food and contribute to the anorexia of aging.

OBJECTIVE

To evaluate the relationship between frailty and taste and smell perception in elderly people living in urban areas.

DESIGN

Data from the baseline evaluation of 768 residents aged ≥ 65 years who enrolled in a comprehensive geriatric health examination survey was analyzed. Fourteen out of 29-items of Appetite, Hunger, Sensory Perception questionnaire (AHSP), frailty, age, sex, BMI, chronic conditions and IADL were evaluated. AHSP was analyzed as the total score of 8 taste items (T) and 6 smell items (S). Frailty was diagnosed using a modified Fried's frailty criteria.

RESULTS

The area under the receiver operator curves for detection of frailty demonstrated that T (0.715) had moderate accuracy, but S (0.657) had low accuracy. The cutoffs, sensitivity, specificity and Youden Index (YI) values for each perception were T: Cutoff 26.5 (YI: 0.350, sensitivity: 0.639, specificity: 0.711) and S: Cutoff 18.5 (YI: 0.246, sensitivity: 0.690, specificity: 0.556). Results from multiple logistic regression models, after adjusting for age, sex, IADL and chronic conditions showed that participants under the T cutoff were associated with exhaustion and those below the S cutoff were associated with slow walking speed. The adjusted logistic models for age, sex, IADL and chronic conditions showed significant association between T and frailty (OR 2.81, 95% CI 1.29-6.12), but not between S and frailty (OR 1.73, 95% CI 0.83-3.63).

CONCLUSIONS

Taste and smell perception, particularly taste perception, were associated with a greater risk of frailty in community-dwelling elderly people. These results suggest that lower taste and smell perception may be an indicator of frailty in old age.

Variants associated with autoimmune Type 1 diabetes in Japanese children: implications for age-specific effects of cis-regulatory haplotypes at 17q12-q21

AIMS

The aim of this study was to clarify the significance of previously reported susceptibility variants in the development of autoimmune Type 1 diabetes in non-white children. Tested variants included rs2290400, which has been linked to Type 1 diabetes only in one study on white people. Haplotypes at 17q12-q21 encompassing rs2290400 are known to determine the susceptibility of early-onset asthma by affecting the expression of flanking genes.

METHODS

We genotyped 63 variants in 428 Japanese people with childhood-onset autoimmune Type 1 diabetes and 457 individuals without diabetes. Possible association between variants and age at diabetes onset was examined using age-specific quantitative trait locus analysis and ordered-subset regression analysis.

RESULTS

Ten variants, including rs2290400 in GSDMB, were more frequent among the people with Type 1 diabetes than those without diabetes. Of these, rs689 in INS and rs231775 in CTLA4 yielded particularly high odds ratios of 5.58 (corrected P value 0.001; 95% CI 2.15-14.47) and 1.64 (corrected P value 5.3 × 10^-5 ; 95% CI 1.34-2.01), respectively. Age-specific effects on diabetes susceptibility were suggested for rs2290400; heterozygosity of the risk alleles was associated with relatively early onset of diabetes, and the allele was linked to the phenotype exclusively in the subgroup of age at onset ≤ 5.0 years.

CONCLUSIONS

The results indicate that rs2290400 in GSDMB and polymorphisms in INS and CTLA4 are associated with the risk of Type 1 diabetes in Japanese children. Importantly, cis-regulatory haplotypes at 17q12-q21 encompassing rs2290400 probably determine the risk of autoimmune Type 1 diabetes predominantly in early childhood.

A glial K(+) /Cl(-) cotransporter modifies temperature-evoked dynamics in Caenorhabditis elegans sensory neurons

K(+) /Cl(-) cotransporters (KCCs) are known to be crucial in the control of neuronal electrochemical Cl(-) gradient. However, the role of these proteins in glial cells remains largely unexplored despite a number of studies showing expression of KCC proteins in glial cells of many species. Here, we show that the Caenorhabditis elegans K(+) /Cl(-) cotransporter KCC-3 is expressed in glial-like cells and regulates the thermosensory behavior through modifying temperature-evoked activity of a thermosensory neuron. Mutations in the kcc-3 gene were isolated from a genetic screen for mutants defective in thermotaxis. KCC-3 is expressed and functions in the amphid sheath glia that ensheathes the AFD neuron, a major thermosensory neuron known to be required for thermotaxis. A genetic analysis indicated that the regulation of the thermosensory behavior by KCC-3 is mediated through AFD, and we further show that KCC-3 in the amphid sheath glia regulates the dynamics of the AFD activity. Our results show a novel mechanism by which the glial KCC-3 protein non-cell autonomously modifies the stimulus-evoked activity of a sensory neuron and highlights the functional importance of glial KCC proteins in modulating the dynamics of a neural circuitry to control an animal behavior.

Effects of emulsifying components in the continuous phase of cream on the stability of fat globules and the physical properties of whipped cream

The emulsifying components in cream are very important in controlling the physical characteristics of whipped cream. The effects of those components on the stability of fat globules and the physical characteristics of whipped cream were investigated. A low-molecular-weight emulsifier, and protein ingredients such as sodium caseinate and a casein partial hydrolysate (casein peptides), were used as emulsifying components in this investigation. The viscosity of deaerated whipped cream (called the serum viscosity) was measured to evaluate the degree of fat-globule aggregation. Furthermore, the shape-retention ability, which is the degree of reduction in the firmness of whipped cream between immediately after whipping and after 1d of refrigeration, was explored. The addition of the low-molecular-weight emulsifier in the continuous phase of dairy cream, which does not contain added low-molecular-weight emulsifiers, increased the stability of the fat globules and reduced the shape-retention ability of the whipped cream. The addition of protein ingredients (sodium caseinate and casein peptides) to the continuous phase of dairy cream had little effect. However, the addition of casein peptide in the continuous phase of dairy cream together with the low-molecular-weight emulsifier reduced the effect of the low-molecular-weight emulsifier on the stabilization of fat globules and the shape-retention ability of the whipped cream. The addition of casein peptide did not recover the serum viscosity; thus, other mechanisms might underlie this phenomenon.

Structures of an ATP-independent Lon-like protease and its complexes with covalent inhibitors

The Lon proteases are a unique family of chambered proteases with a built-in AAA+ (ATPases associated with diverse cellular activities) module. Here, crystal structures of a unique member of the Lon family with no intrinsic ATPase activity in the proteolytically active form are reported both alone and in complexes with three covalent inhibitors: two peptidomimetics and one derived from a natural product. This work reveals the unique architectural features of an ATP-independent Lon that selectively degrades unfolded protein substrates. Importantly, these results provide mechanistic insights into the recognition of inhibitors and polypeptide substrates within the conserved proteolytic chamber, which may aid the development of specific Lon-protease inhibitors.

Respiratory syncytial virus infection in children with severe motor and intellectual disabilities

Children with severe motor intellectual disabilities (SMID) are at high risk of death from acute viral lower respiratory tract infections (LRTI). Although respiratory syncytial virus (RSV) is the most common cause of viral LRTI in children, there have been a few reports on the relationship between SMID and the severity of RSV-LRTI. The aim of the present study is to assess the influence of RSV-LRTI in children with SMID. A case-control study composed of children with SMID (n = 18) and previously healthy children (n = 43) less than 16 years old hospitalized for RSV-LRTI was performed during five consecutive RSV seasons. The clinical presentation and the laboratory data in the SMID group were compared with those in the non-SMID group. In the bivariate analysis, the median age of the SMID group was higher than that of the non-SMID group (p = 0.002). Children with SMID had an increased risk for ventilation support (p = 0.057). The count of neutrophils in the SMID group was significantly increased (p = 0.012), whereas the proportion of bacterial co-infection was lower than that in the non-SMID group (p = 0.005). Multivariate logistic analysis showed that SMID was associated with longer oxygen usage [>7 days: odds ratio (OR) 5.309, p = 0.033]. The present study revealed that children with SMID were prone to developing hypoxia by RSV-LRTI. The strategies for the treatment and prevention of RSV infection need to be improved in SMID children.

Histo-blood group gene polymorphisms as potential genetic modifiers of the development of coronary artery lesions in patients with Kawasaki disease

Abnormal immunological responses to certain microbial agents may play a crucial role in the pathogenesis of Kawasaki disease (KD). The association studies between histo-blood group genes (Lewis and ABO blood types) and various types of infectious diseases or vasculopathy have been carried out based on the fact that glycosylated antigens could directly mediate microbial infections. We attempted to clarify the role of blood type antigens in the development of KD and coronary artery lesions in KD patients. The subjects included 164 KD patients enrolled from 1998 to 2003 (1st group), 232 patients from 2004 to 2009 (2nd group), and 223 healthy children and 118 patients with growth hormone deficiency as controls. The genotyping of the FUT2 and FUT3 genes, and ABO genotypes, was determined with the TaqMan SNP assay and allele-specific polymerase chain reaction. No significant differences were observed in the genotypes and allele frequencies of the FUT2 and FUT3 genes between the groups. The frequency of the BB blood genotype was significantly higher in KD patients with coronary artery lesions in the 1st and 2nd groups than in the controls (17% and 14% vs. 5%, P = 0.0020). This is the first report to investigate the roles of ABO and Lewis blood types in the development of KD, and in the formation of coronary artery lesions in KD patients. These data suggest that the ABO blood type may play a role in the development of coronary artery lesions in KD patients.

Advantages of intra-capsular micro-enucleation of schwannoma arising from extremities

BACKGROUND

Schwannoma is the most common tumor of the peripheral nerves, with surgical enucleation being the established treatment modality. However, some schwannomas cannot be easily enucleated and this sometimes results in iatrogenic nerve injury even with atraumatic procedures. Here we present a retrospective review of the management of schwannoma in the extremities and compare clinical outcomes from the two techniques of extra-capsular and intra-capsular enucleation.

METHODS

We reviewed 36 schwannomas from 35 patients who underwent surgical excision of schwannomas arising from the extremities. Twenty had undergone extra-capsular resection and 16 had undergone enucleation using the intra-capsular technique. The post-operative neurological deficits were graded as minor, major, and transient. The duration of symptoms, maximum tumor diameter and site of occurrence were compared between patients with the three grades of deficit.

RESULTS

In total, 22 patients developed no sensory changes following enucleation of schwannoma or only temporary and minor changes that had fully resolved within 6 months. Ten patients developed new neurological deficits following surgery that took longer than 6 months to resolve. Four patients experienced new motor deficits or paresthesia following operation that had still not recovered at the final follow-up, all of whom underwent enucleation using the extra-capsular technique. Neurological deficit after enucleation was significantly lower using the intra-capsular compared with the extra-capsular technique. Patient age, duration of symptoms, maximum diameter of the tumor and site of occurrence did not influence the neurological deficit following enucleation of schwannoma.

CONCLUSION

These results support intra-capsular micro-enucleation as a safe and reliable treatment for every type of schwannoma. To minimize the risk of nerve injury, en bloc resection should not be used because the main purpose of schwannoma surgery is the relief of symptoms, not tumor resection. Thorough pre-operative counseling of patients to inform them of the potential occurrence of neurological deficit is important.

Transfer of latissimus dorsi muscle for the functional reconstruction of quadriceps femoris muscle following oncological resection of sarcoma in the thigh

Wide resection of tumours in the anterior compartment of the thigh frequently requires en bloc removal of the quadriceps femoris muscle. Such resection can result in significantly decreased muscle power of knee extension. Functional muscle transfer is a beneficial tool for the reconstruction process. Until now, however, there have been few reports on the outcome of quadriceps muscle reconstruction using free innervated muscle transfer. We reviewed 14 patients (seven women and seven men, mean age 53 years). The extent of tumour invasion required resection of the entire quadriceps in four cases, of three heads in six cases and of two heads in the remaining four cases. Local recurrence occurred in one patient only, and there were no major complications. In the four patients with entire resection of the quadriceps, the postoperative muscle manual test (MMT) result was 0-1 (mean, 0.5), but this recovered to between 2 and 3 (mean 2.3) after a mean follow-up of 70 months. In the six cases with resection of three heads, the MMT test result was 2 and active knee extension recovered almost fully. Transfer of free, functional latissimus dorsi muscle is best indicated for cases in which the entire quadriceps or three heads are resected. Active knee extension can be expected to improve to an MMT score of 2 after reinnervation of the transferred muscle. Microsurgical reconstruction following resection of soft-tissue sarcoma provides adequate functional and coverage reconstruction, together with better local control by allowing wider surgical margins.

Genetic variation of vascular endothelial growth factor pathway does not correlate with the severity of retinopathy of prematurity

OBJECTIVE

The aim of this study was to assess the genetic effects of the vascular endothelial growth factor (VEGF) pathway on retinopathy of prematurity (ROP).

STUDY DESIGN

A prospective study from a tertiary center that enrolled 204 Japanese infants (<35 weeks of gestational age (GA)) having no anomalies. ROP developed in 127, but not in 77 infants. The relative severity was defined as non-severe, moderate and severe ROP for GA, based on the staging criteria. VEGF (g.-634G>C, g.+13553C>T) and VEGF-receptor (KDR g.+4422(AC)11 to 14, Flt-1 c.+6724(TG)13 to 23) gene polymorphisms and clinical variables were assessed by uni/multivariate analyses.

RESULT

The frequency of polymorphisms did not differ between ROP and non-ROP patients. The TT genotype of g.+13553 showed a higher odds ratio for non-severe ROP than CC genotype (P=0.006). Multivariate analyses indicated that low birth weight, blood transfusion and respiratory distress syndrome, but not polymorphisms, were the risk factors of advanced ROP (≥ stage 3).

CONCLUSION

A genotype of the VEGF pathway weakly affects the severity of ROP compared with other clinical factors.

Congenital multiple pituitary hormone deficiency associated with hyperammonemia: a case report with a short review of the literature

We herein report a case study of a female newborn with multiple pituitary hormone deficiencies who presented with generalized seizures, hypoglycemia and hyperammonemia at 18 h after birth. In addition, we review the association of hyperammonemia in neonates with multiple pituitary hormone deficiencies reported in the previous literature. This unrecognized association should be taken into account for the early diagnosis and treatment of these patients.

GDP-bound and nucleotide-free intermediates of the guanine nucleotide exchange in the Rab5·Vps9 system

Many GTPases regulate intracellular transport and signaling in eukaryotes. Guanine nucleotide exchange factors (GEFs) activate GTPases by catalyzing the exchange of their GDP for GTP. Here we present crystallographic and biochemical studies of a GEF reaction with four crystal structures of Arabidopsis thaliana ARA7, a plant homolog of Rab5 GTPase, in complex with its GEF, VPS9a, in the nucleotide-free and GDP-bound forms, as well as a complex with aminophosphonic acid-guanylate ester and ARA7·VPS9a(D185N) with GDP. Upon complex formation with ARA7, VPS9 wedges into the interswitch region of ARA7, inhibiting the coordination of Mg(2+) and decreasing the stability of GDP binding. The aspartate finger of VPS9a recognizes GDP β-phosphate directly and pulls the P-loop lysine of ARA7 away from GDP β-phosphate toward switch II to further destabilize GDP for its release during the transition from the GDP-bound to nucleotide-free intermediates in the nucleotide exchange reaction.

Association study between B- and T-lymphocyte attenuator gene and type 1 diabetes mellitus or systemic lupus erythematosus in the Japanese population

This study is to elucidate whether the B- and T-lymphocyte attenuator (BTLA) gene is a new susceptibility gene for the development of type 1 diabetes (T1D) and systemic lupus erythematosus (SLE). As a result, this study did not find any genetic contribution of the BTLA gene to the development of T1D and SLE in Japanese population.

Intrasacral schwannoma: clinical presentation, diagnosis and management

Intrasacral schwannoma is a very rare lesion. We report here three cases of intrasacral schwannoma originating within the sacrum and discuss their clinical presentation, diagnosis and management. Complete excision would appear to be the treatment of choice, but conservative treatment is an option provided the tumour causes no serious symptoms.

Purification, crystallization and preliminary X-ray crystallographic analysis of Rab27a GTPase in complex with exophilin4/Slp2-a effector

By switching between GTP-active and GDP-inactive conformations, small Ras GTPases partly regulate membrane trafficking, cell growth and cytoskeleton dynamics. Among Rab GTPases, the Rab27 subfamily, which comprises Rab27a and Rab27b, controls the proper targeting of secretory vesicles to the plasma membrane. GppNHp-bound Rab27a in complex with the Rab27-binding domain of exophilin4/Slp2-a effector has been purified and crystallized for structural studies. The crystals belong to space group P2(1)2(1)2(1) and a complete data set was collected to a resolution of 1.8 A. Eventually, the structural characterization of the Rab27a-exophilin4/Slp2-a complex will clarify Rab27 recognition by its effectors prior to vesicle tethering and docking.

Low-grade central osteosarcoma mimicking fibrous dysplasia: a report of two cases

Low-grade central osteosarcoma is an unusual variant of conventional osteosarcoma. We present here two rare cases of low-grade central osteosarcoma resembling fibrous dysplasia. A 24-year-old woman diagnosed as fibrous dysplasia was treated with intra-lesional excision and curettage of the tumor but tumor recurred at 4 months after surgery. Distal femoral en-bloc resection was performed followed by arthroplasty with mega-prosthesis of the knee. A 57-year-old man diagnosed as central osteosarcoma was treated with wide excision of the tumor, followed by reconstruction with the vascularized fibula graft combined with an autogenous irradiated bone graft. Because of the difficulty in distinguishing low-grade central osteosarcoma from a benign lesion, open biopsy is needed to obtain a large tumor sample. Careful clinical and pathological evaluation is required to obtain a definite diagnosis. The treatment of low-grade central osteosarcoma is en-block resection with wide surgical margins.

Construct validity of the Enneking score for measuring function in patients with malignant or aggressive benign tumours of the upper limb

We evaluated the construct validity of the Musculoskeletal Tumour Society rating scale (Enneking score) as a functional measure for patients with sarcoma involving the upper limb. We compared the Enneking score by examining the correlation between two patient-derived outcome measures, the Disability of the Arm, Shoulder, and Hand (DASH) questionnaire and the Medical Outcomes Study Short Form-36 (SF-36) as indicators of functional status in 40 patients with malignant or aggressive benign bone and soft-tissue tumours of the upper limb who had undergone surgical treatment. The frequency distributions were similar among the three scoring systems. As for the validity, Spearman's rank correlation coefficient of the Enneking score to the DASH questionnaire was -0.79 and that of the Enneking to the SF-36 subscales ranged from 0.38 to 0.60. Despite being a measure from the surgeon's perspective, the Enneking score was shown to be a valid indicator of physical disability in patients with malignant or aggressive benign tumours of the upper limb and reflected their opinion.

The Leu544Ile polymorphism of the growth hormone receptor gene affects the serum cholesterol levels during GH treatment in children with GH deficiency

OBJECTIVE

The cellular effects of growth hormone (GH) are mediated by the interaction between GH and the GH receptor (GHR). We investigated the association between polymorphisms in GHR and changes in height standard deviation scores (SDS), and lipid metabolism during GH treatment for GH-deficient children.

DESIGN

A 1-year study on growth rate and lipid metabolism under GH treatment.

PATIENTS

Eighty-three children (61 boys and 22 girls) with GH deficiency were treated with GH for 1 year after diagnosis.

INTERVENTION

The patients were treated with recombinant human GH (0.19 mg/kg/week) for at least 1 year after diagnosis. The growth rates and biochemical parameters for lipid metabolism were measured both before and during treatment. Four single nucleotide polymorphisms (SNPs) in the GHR gene, Cys440Phe, Pro495Thr, Leu544Ile and Pro579Thr, and exon 3 deletion polymorphisms were genotyped by direct sequencing and multiplex PCR.

RESULTS

We found no significant association between GHR polymorphisms and changes in height SDS during GH treatment. The total cholesterol levels of the GH-deficient boys with Ile/Ile at codon 544 showed significantly higher cholesterol levels before GH treatment and then maintained high levels during the GH treatment, compared to those with other genotypes. No other polymorphisms seemed to have any apparent effects on lipid metabolism.

CONCLUSION

The Leu544Ile polymorphism of the GHR gene is associated with cholesterol levels in boys with GH deficiency.

Structure of the small GTPase Rab27b shows an unexpected swapped dimer

Members of the Rab family of small GTPases regulate membrane traffic within the cell by recruiting their specific effectors in a nucleotide-dependent manner. The Rab27 subfamily consists of Rab27a and Rab27b, which share 70% sequence identity. By interacting with a large set of effector proteins such as melanophilin and granuphilin, both Rab27a and Rab27b regulate the exocytosis of secretory lysosomes. Here, the crystal structures of mouse Rab27b in complex with GDP have been determined in three distinct crystal lattices. Surprisingly, Rab27b-GDP exists in an open conformation with protruding switch and interswitch regions, which are stabilized through dimerization by means of domain-swapping in the crystals. In contrast, small-angle X-ray scattering measurements showed an extended monomer form of Rab27b in solution. The observed dimer formation of Rab27b-GDP in the crystals would restrain the highly flexible switch regions. Possible biological implications of this atypical structure of Rab27b and its plausible influence in effector interaction are discussed.

Molecular Basis for Autoregulatory Interaction Between GAE Domain and Hinge Region of GGA1

Golgi-localizing, gamma-adaptin ear domain homology, ADP ribosylation factor-binding (GGA) proteins and the adaptor protein (AP) complex, AP-1, are involved in membrane traffic between the trans Golgi network and the endosomes. The gamma-adaptin ear (GAE) domain of GGAs and the gamma1 ear domain of AP-1 interact with an acidic phenylalanine motif found in accessory proteins. The GAE domain of GGA1 (GGA1-GAE) interacts with a WNSF-containing peptide derived from its own hinge region, although the peptide sequence deviates from the standard acidic phenylalanine motif. We report here the structure of GGA1-GAE in complex with the GGA1 hinge peptide, which revealed that the two aromatic side chains of the WNSF sequence fit into a hydrophobic groove formed by aliphatic portions of the side chains of conserved arginine and lysine residues of GGA1-GAE, in a similar manner to the interaction between GGA-GAEs and acidic phenylalanine sequences from the accessory proteins. Fluorescence quenching experiments indicate that the GGA1 hinge region binds to GGA1-GAE and competes with accessory proteins for binding. Taken together with the previous observation that gamma1 ear binds to the GGA1 hinge region, the interaction between the hinge region and the GAE domain underlies the autoregulation of GGA function in clathrin-mediated trafficking through competing with the accessory proteins and the AP-1 complex.

Phenotypic and genetic analyses of T-cell-mediated immunoregulation in patients with Type 1 diabetes

AIMS

To investigate the contribution of regulatory T cells and co-stimulatory molecules in CD4(+) T cells to the development of Type 1 diabetes (T1D).

METHODS

Twelve patients with T1D, nine patients with systemic lupus erythematosus (SLE), and 12 age-matched healthy control subjects participated. We analysed the proportions of CD25(+)CD4(+) T cells and natural killer T cells (NKT cells), and the expression levels of Foxp3, CTLA-4, CD28, ICOS, PD-1 and BTLA in peripheral blood mononuclear cells and purified CD4(+) T cells.

RESULTS

There were no significant differences in the proportions of CD25(+) CD4(+) T cells or NKT cells among the three groups. PD-1 expression levels of peripheral CD4(+) T cells from T1D patients were significantly lower than those from healthy control subjects (P = 0.00066). In contrast, PD-1 expression levels were similar in SLE patients and healthy control subjects. The expression levels of Foxp3, CTLA-4, CD28, ICOS and BTLA were similar in the three groups.

CONCLUSIONS

Decreased expression of the PD-1 gene in CD4(+) T cells may contribute to the development and/or maintenance of autoimmune T1D. As the population studied was small and heterogeneous, further studies are required to confirm the findings.

Persistent diffusion abnormalities in the brain stem of three children with mitochondrial diseases

We report 2 children (patients 1 and 2) with Kearns-Sayre syndrome and 1 (patient 3) with Leigh syndrome, who underwent serial diffusion-weighted MR imaging (DWI) studies for 2.8 (patient 1), 4.2 (patient 2), and 1.0 years (patient 3). The DWI revealed the persistent hyperintense signals in the pontine and mesencephalic tegmenta. The apparent diffusion coefficient in the affected regions remained constantly low, suggesting that cytotoxic edema and spongiform degenerations may compose these brain stem lesions.

A new navigation system based on cephalograms and dental casts for oral and maxillofacial surgery

Intraoperative navigation systems help surgeons to accurately carry out preoperative plans without injuring anatomically important structures. A system is evaluated that uses cephalograms instead of computed tomographic (CT) scans to create images. Three-dimensional (3D) dental casts provide registration between imaging data and the patient. Cephalograms are widely employed in orthognathic and oral and maxillofacial surgery and expose patients to lower doses of radiation than CT. The system uses a dental cast to register the operation field to a pair of frontal and lateral cephalograms. The cast is transformed to 3D data with a laser scanner and a programme that runs on a personal computer. 3D data describing the dental cast, cephalograms and the oral and maxillofacial region of the patient are integrated with specialized software. The optical tracking system for navigation uses charged-coupled-device (CCD) video cameras and light-emitting diodes (LEDs). Two CCD video cameras follow the 3D coordinates of LED assemblies attached to the head, lower jaw and a handpiece. Errors occurring when a dental cast was transformed to 3D data ranged from 0.08 to 0.21 mm. Mean errors were 0.71 mm (0.21-1.09 mm) for the right maxillary central incisor, 0.62 mm (0.04-1.69 mm) for the right maxillary 2nd molar and 1.02 mm (0.23-1.47 mm) for the left maxillary 2nd molar. This surgical navigation system is sufficiently accurate for use in oral and maxillofacial surgery.

Development of an automated large-scale protein-crystallization and monitoring system for high-throughput protein-structure analyses

Protein crystallization remains one of the bottlenecks in crystallographic analysis of macromolecules. An automated large-scale protein-crystallization system named PXS has been developed consisting of the following subsystems, which proceed in parallel under unified control software: dispensing precipitants and protein solutions, sealing crystallization plates, carrying robot, incubators, observation system and image-storage server. A sitting-drop crystallization plate specialized for PXS has also been designed and developed. PXS can set up 7680 drops for vapour diffusion per hour, which includes time for replenishing supplies such as disposable tips and crystallization plates. Images of the crystallization drops are automatically recorded according to a preprogrammed schedule and can be viewed by users remotely using web-based browser software. A number of protein crystals were successfully produced and several protein structures could be determined directly from crystals grown by PXS. In other cases, X-ray quality crystals were obtained by further optimization by manual screening based on the conditions found by PXS.

Association study of polymorphisms in SOCS family genes with type 1 diabetes mellitus

Suppressors of cytokine signalling (SOCS) proteins play important roles in the negative regulation of cytokine signal. We first searched for polymorphisms in SOCS-1, SOCS-3 and SOCS-5 genes, and examined the association of the polymorphisms with type 1 diabetes (T1D). As a result, we did not find any significant associations between SOCS genes and T1D.

Structure of the ectodomain of Drosophila peptidoglycan-recognition protein LCa suggests a molecular mechanism for pattern recognition

The peptidoglycan-recognition protein LCa (PGRP-LCa) is a transmembrane receptor required for activation of the Drosophila immune deficiency pathway by monomeric Gram-negative peptidoglycan. We have determined the crystal structure of the ectodomain of PGRP-LCa at 2.5-A resolution and found two unique helical insertions in the LCa ectodomain that disrupt an otherwise L-shaped peptidoglycan-docking groove present in all other known PGRP structures. The deficient binding of PGRP-LCa to monomeric peptidoglycan was confirmed by biochemical pull-down assays. Recognition of monomeric peptidoglycan involves both PGRP-LCa and -LCx. We showed that association of the LCa and LCx ectodomains in vitro depends on monomeric peptidoglycan. The presence of a defective peptidoglycan-docking groove, while preserving a unique role in mediating monomeric peptidoglycan induction of immune response, suggests that PGRP-LCa recognizes the exposed structural features of a monomeric muropeptide when the latter is bound to and presented by the ectodomain of PGRP-LCx. Such features include N-acetyl glucosamine and the anhydro bond in the glycan of the muropeptide, which have been demonstrated to be critical for immune stimulatory activity.