Properties of Spontaneous rpsL Mutant of Streptomyces albus KO-1297

The Streptomyces albus J1074 strain remains one of the most popular platforms for the discovery of new natural compounds due to the expression of biosynthetic gene clusters (BGCs) from the microorganisms of the Actinobacteria class. Different methods were tested to provide a maximal expression of heterologous BGCs in this strain. However, there is still no description of the properties of spontaneous J1074 mutants in the rpsL gene encoding a ribosomal protein S12. The interest in such mutations in actinobacteria is due to the fact that they provide a considerable increase in the antibiotic activity. In this work, we describe the isolation and characterization of the S. albus KO-1297 strain, which contains a spontaneous missense mutation in the rpsL gene leading to a Lys88Glu substitution in the protein S12. As compared with the initial strain, this mutant exhibits an increased resistance to streptomycin and higher antibiotic productivity. The KO-1297 strain and genetically engineered rpsL^K88E mutant K88E are not identical in their ability to produce antibiotics. KO-1297 also exhibits a certain level of instability of rpsL mutation. The genomes of KO-1297 and its rpsL^WT revertant contain the mutations that can cause phenotypic differences between these strains (as well as between them and SAM2 and K88E strains).

The sodium-glucose cotransporter-2 inhibitor Tofogliflozin prevents the progression of nonalcoholic steatohepatitis-associated liver tumors in a novel murine model

BACKGROUND

Diabetes and obesity contribute to the pathogenesis of nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). However, how diabetes and obesity accelerate liver tumorigenesis remains to be fully understood. Moreover, to verify the therapeutic potential of anti-diabetic drugs, there exists a strong need for appropriate animal models that recapitulate human pathophysiology of NASH and HCC.

METHODS

We established a novel murine model of NASH-associated liver tumors using genetically obese melanocortin 4 receptor-deficient mice fed on Western diet in combination with a chemical procarcinogen, and verified the validity of our model in evaluating drug efficacy.

FINDINGS

Our model developed multiple liver tumors together with obesity, diabetes, and NASH within a relatively short period (approximately 3 months). In this model, sodium glucose cotransporter 2 inhibitor Tofogliflozin prevented the development of NASH-like liver phenotypes and the progression of liver tumors. Tofogliflozin attenuated p21 expression of hepatocytes in non-tumorous lesions in the liver.

INTERPRETATION

Tofogliflozin treatment attenuates cellular senescence of hepatocytes under obese and diabetic conditions. This study provides a unique animal model of NASH-associated liver tumors, which is applicable for assessing drug efficacy to prevent or treat NASH-associated HCC.

C-type lectin Mincle mediates cell death-triggered inflammation in acute kidney injury

Accumulating evidence indicates that cell death triggers sterile inflammation and that impaired clearance of dead cells causes nonresolving inflammation; however, the underlying mechanisms are still unclear. Here, we show that macrophage-inducible C-type lectin (Mincle) senses renal tubular cell death to induce sustained inflammation after acute kidney injury in mice. Mincle-deficient mice were protected against tissue damage and subsequent atrophy of the kidney after ischemia–reperfusion injury. Using lipophilic extract from the injured kidney, we identified β-glucosylceramide as an endogenous Mincle ligand. Notably, free cholesterol markedly enhanced the agonistic effect of β-glucosylceramide on Mincle. Moreover, β-glucosylceramide and free cholesterol accumulated in dead renal tubules in proximity to Mincle-expressing macrophages, where Mincle was supposed to inhibit clearance of dead cells and increase proinflammatory cytokine production. This study demonstrates that β-glucosylceramide in combination with free cholesterol acts on Mincle as an endogenous ligand to induce cell death–triggered, sustained inflammation after acute kidney injury.

Hollow fiber-combined glucose-responsive gel technology as an in vivo electronics-free insulin delivery system

Accumulating evidence demonstrates that not only sustained elevation of blood glucose levels but also the glucose fluctuation represents key determinants for diabetic complications and mortality. Current closed-loop insulin therapy option is limited to the use of electronics-based systems, although it poses some technical issues with high cost. Here we demonstrate an electronics-free, synthetic boronate gel-based insulin-diffusion-control device technology that can cope with glucose fluctuations and potentially address the electronics-derived issues. The gel was combined with hemodialysis hollow fibers and scaled suitable for rats, serving as a subcutaneously implantable, insulin-diffusion-active site in a manner dependent on the subcutaneous glucose. Continuous glucose monitoring tests revealed that our device not only normalizes average glucose level of rats, but also markedly ameliorates the fluctuations over timescale of a day without inducing hypoglycemia. With inherent stability, diffusion-dependent scalability, and week-long & acute glucose-responsiveness, our technology may offer a low-cost alternative to current electronics-based approaches.

Here, the authors develop an in vivo insulin delivery system which consists of a glucose responsive gel combined with hemodialysis hollow fibers. This system is electronics-free, temperature independent, and can stably sustain acute glucose-responsiveness in rats.

Dipeptidyl peptidase-4 inhibition prevents nonalcoholic steatohepatitis-associated liver fibrosis and tumor development in mice independently of its anti-diabetic effects

Nonalcoholic steatohepatitis (NASH) is a hepatic phenotype of the metabolic syndrome, and increases the risk of cirrhosis and hepatocellular carcinoma (HCC). Although increasing evidence points to the therapeutic implications of certain types of anti-diabetic agents in NASH, it remains to be elucidated whether their effects on NASH are independent of their effects on diabetes. Genetically obese melanocortin 4 receptor–deficient (MC4R-KO) mice fed Western diet are a murine model that sequentially develops hepatic steatosis, NASH, and HCC in the presence of obesity and insulin resistance. In this study, we investigated the effect of the dipeptidyl peptidase-4 (DPP-4) inhibitor anagliptin on NASH and HCC development in MC4R-KO mice. Anagliptin treatment effectively prevented inflammation, fibrosis, and carcinogenesis in the liver of MC4R-KO mice. Interestingly, anagliptin only marginally affected body weight, systemic glucose and lipid metabolism, and hepatic steatosis. Histological data and gene expression analysis suggest that anagliptin treatment targets macrophage activation in the liver during the progression from simple steatosis to NASH. As a molecular mechanism underlying anagliptin action, we showed that glucagon-like peptide-1 suppressed proinflammatory and profibrotic phenotypes of macrophages in vitro. This study highlights the glucose metabolism–independent effects of anagliptin on NASH and HCC development.

Synthetic "smart gel" provides glucose-responsive insulin delivery in diabetic mice

Although previous studies have attempted to create "electronics-free" insulin delivery systems using glucose oxidase and sugar-binding lectins as a glucose-sensing mechanism, no successful clinical translation has hitherto been made. These protein-based materials are intolerant of long-term use and storage because of their denaturing and/or cytotoxic properties. We provide a solution by designing a protein-free and totally synthetic material-based approach. Capitalizing on the sugar-responsive properties of boronic acid, we have established a synthetic polymer gel-based insulin delivery device confined within a single catheter, which exhibits an artificial pancreas-like function in vivo. Subcutaneous implantation of the device in healthy and diabetic mice establishes a closed-loop system composed of "continuous glucose sensing" and "skin layer"-regulated insulin release. As a result, glucose metabolism was controlled in response to interstitial glucose fluctuation under both insulin-deficient and insulin-resistant conditions with at least 3-week durability. Our "smart gel" technology could offer a user-friendly and remarkably economic (disposable) alternative to the current state of the art, thereby facilitating availability of effective insulin treatment not only to diabetic patients in developing countries but also to those patients who otherwise may not be strongly motivated, such as the elderly, infants, and patients in need of nursing care.

Antifibrotic effect of pirfenidone in a mouse model of human nonalcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is characterized by steatosis with lobular inflammation and hepatocyte injury. Pirfenidone (PFD) is an orally bioavailable pyridone derivative that has been clinically used for the treatment of idiopathic pulmonary fibrosis. However, it remains unknown whether PFD improves liver fibrosis in a mouse model with human NASH-like phenotypes. In this study, we employed melanocortin 4 receptor-deficient (MC4R-KO) mice as a mouse model with human NASH-like phenotypes to elucidate the effect and action mechanisms of PFD on the development of NASH. PFD markedly attenuated liver fibrosis in western diet (WD)-fed MC4R-KO mice without affecting metabolic profiles or steatosis. PFD prevented liver injury and fibrosis associated with decreased apoptosis of liver cells in WD-fed MC4R-KO mice. Pretreatment of PFD inhibited the tumor necrosis factor-α (TNF-α)-induced liver injury and fibrogenic responses associated with decreased apoptosis of liver cells in wild-type mice. PFD also prevented TNF-α-induced hepatocyte apoptosis in vitro with reduced activation of caspase-8 and -3. This study provides evidence for the antifibrotic effect of PFD in a mouse model of human NASH. The data of this study highlight hepatocyte apoptosis as a potential therapeutic target, and suggest that PFD can be repositioned as an antifibrotic drug for human NASH.

The H3K9 methyltransferase Setdb1 regulates TLR4-mediated inflammatory responses in macrophages

Proinflammatory cytokine production in macrophages involves multiple regulatory mechanisms, which are affected by environmental and intrinsic stress. In particular, accumulating evidence has suggested epigenetic control of macrophage differentiation and function mainly in vitro. SET domain, bifurcated 1 (Setdb1, also known as Eset) is a histone 3 lysine 9 (H3K9)-specific methyltransferase and is essential for early development of embryos. Here we demonstrate that Setdb1 in macrophages potently suppresses Toll-like receptor 4 (TLR4)-mediated expression of proinflammatory cytokines including interleukin-6 through its methyltransferase activity. As a molecular mechanism, Setdb1-deficiency decreases the basal H3K9 methylation levels and augments TLR4-mediated NF-κB recruitment on the proximal promoter region of interleukin-6, thereby accelerating interleukin-6 promoter activity. Moreover, macrophage-specific Setdb1-knockout mice exhibit higher serum interleukin-6 concentrations in response to lipopolysaccharide challenge and are more susceptible to endotoxin shock than wildtype mice. This study provides evidence that the H3K9 methyltransferase Setdb1 is a novel epigenetic regulator of proinflammatory cytokine expression in macrophages in vitro and in vivo. Our data will shed insight into the better understanding of how the immune system reacts to a variety of conditions.

Feeding frequency, but not dietary water content, affects voluntary physical activity in young lean adult female cats

The objective of this study was to investigate whether increased dietary water content and feeding frequency increased voluntary physical activity of young, lean adult female cats. A replicated 4 × 4 Latin square design with a 2 × 2 factorial treatment arrangement (feeding frequency and water content) was used. The 4 treatments consisted of 1 meal daily dry pet food without added water (1D; 12% moisture as is), 1 meal daily dry pet food with added water (1W; 70% total water content), 4 meals daily dry pet food without added water (4D; 12% moisture as is), and 4 meals daily dry pet food with added water (4W; 70% total water content). Eight healthy adult, lean, intact, young, female domestic shorthair cats were used in this experiment. Voluntary physical activity was evaluated using Actical activity monitors placed on collars and worn around the cats' necks for the last 7 d of each experimental period of 14 d. Food anticipatory activity (FAA) was calculated based on 2 h prior to feeding periods and expressed as a percentage of total daily voluntary physical activity. Increased feeding frequency (4 vs. 1 meal daily) resulted in greater average daily activity (P = 0.0147), activity during the light period (P = 0.0023), and light:dark activity ratio (P = 0.0002). In contrast, physical activity during the dark period was not altered by feeding frequency (P > 0.05). Cats fed 4 meals daily had increased afternoon FAA (P= 0.0029) compared with cats fed once daily. Dietary water content did not affect any measure of voluntary physical activity. Increased feeding frequency is an effective strategy to increase the voluntary physical activity of cats. Thus, it may assist in the prevention and management of obesity.

Ten-year incidences of self-reported non-vertebral fractures in Japanese patients with rheumatoid arthritis: discrepancy between disease activity control and the incidence of non-vertebral fracture

Despite improvements in rheumatoid arthritis disease activity of in the past 10 years, the incidence of self-reported non-vertebral fractures did not decrease in our cohort of 9,987 patients. This study may indicate that osteoporosis treatment and non-vertebral fracture prevention remain important regardless of the rheumatoid arthritis disease activity.

INTRODUCTION

Although rheumatoid arthritis (RA) is a risk factor for osteoporosis and fractures, few studies have described the association between disease activity and the fracture incidence in patients with RA. This study aimed to investigate changes in the non-vertebral fracture incidence between 2001 and 2010 in our Institute of Rheumatology Rheumatoid Arthritis (IORRA) cohort.

METHODS

The IORRA is a prospective observational cohort study of Japanese RA patients. A total of 9,987 patients with RA were enrolled in this cohort from 2000 to 2010. The clinical parameter and non-vertebral fracture occurrence data were collected biannually through self-reported questionnaires. Incidences of self-reported non-vertebral fractures were also analyzed via standardization according to gender, age, and disease activity during each 2-year period.

RESULTS

From 2001 to 2010, the percentage of patients with 28-joint disease activity score remission increased from 7.8 to 39.7%, prednisolone intake decreased from 51.4 to 41.3%, and bisphosphonate intake increased from 5.0 to 23.4%. The non-vertebral fracture incidence rates were 24.6/1,000 person-years in 2001 and 35.5/1,000 person-years in 2010, with no apparent change even after standardization. The overall non-vertebral fracture incidence was significantly higher in the autumn/winter than in the spring/summer (p = 0.02).

CONCLUSION

Despite improvements in disease activity and functional disability, the non-vertebral fracture incidence exhibited no apparent change between 2001 and 2010 in our patients with RA. Osteoporosis treatment and non-vertebral fracture prevention remain important regardless of the disease control in patients with RA.

Ulnar nerve strain at the elbow in patients with cubital tunnel syndrome: effect of simple decompression

Simple decompression of the ulnar nerve at the elbow has not been shown to reduce nerve strain in cadavers. In this study, ulnar nerve strain at the elbow was measured intraoperatively in 11 patients with cubital tunnel syndrome, before and after simple decompression. Statistical analysis was performed using a paired Student's t-test. Mean ulnar nerve strain before and after simple decompression was 30.5% (range 9% to 69%) and 5.5% (range -2% to 11%), respectively; this difference was statistically significant (p < 0.01) with a statistical power of 96%. Simple decompression reduced ulnar nerve strain in all patients by an average of 24.5%. Our results suggest that the pathophysiology of cubital tunnel syndrome may be multifactorial, being neither a simple compression neuropathy nor a simple traction neuropathy, and simple decompression may be a favourable surgical procedure for cubital tunnel syndrome in terms of decompression and reduction of strain in the ulnar nerve.

Surgical treatment of spontaneous posterior interosseous nerve palsy

We have reviewed 38 surgically treated cases of spontaneous posterior interosseous nerve palsy in 38 patients with a mean age of 43 years (13 to 68) in order to identify clinical factors associated with its prognosis. Interfascicular neurolysis was performed at a mean of 13 months (1 to 187) after the onset of symptoms. The mean follow-up was 21 months (5.5 to 221). Medical Research Council muscle power of more than grade 4 was considered to be a good result. A further 12 cases in ten patients were treated conservatively and assessed similarly.

Of the 30 cases treated surgically with available outcome data, the result of interfascicular neurolysis was significantly better in patients < 50 years old (younger group (18 nerves); good: 13 nerves (72%), poor: five nerves (28%)) than in cases > 50 years old (older group (12 nerves); good: one nerve (8%), poor: 11 nerves (92%)) (p < 0.001). A pre-operative period of less than seven months was also associated with a good result in the younger group (p = 0.01). The older group had a poor result regardless of the pre-operative delay.

Our recommended therapeutic approach therefore is to perform interfascicular neurolysis if the patient is < 50 years of age, and the pre-operative delay is < seven months. If the patient is > 50 years of age with no sign of recovery for seven months, or in the younger group with a pre-operative delay of more than a year, we advise interfascicular neurolysis together with tendon transfer as the primary surgical procedure.

A 100 nm thick InGaN/GaN multiple quantum-well column-crystallized thin film deposited on Si(111) substrate and its micromachining

A 100 nm thick InGaN/GaN multiple quantum-well column-crystallized thin film was deposited on Si(111) substrate, with InN as the interlayer, by molecular beam epitaxy. The diameter of the column crystal is about 40 nm. Transmission electron microscopy images showed clear five-period well layers. Photoluminescence measurements demonstrated a wide emission wavelength from about 500 to 800 nm with the full width at half maximum of 107 nm at room temperature. An unusual photoluminescence peak position shift was observed from the optical measurement. The selected area electron diffraction image demonstrated the hexagonal wurtzite structure of the column crystal. A self-supported GaN-based active subwavelength grating was proposed, and the active subwavelength grating structure was fabricated from the InGaN/GaN quantum-well thin film by a Si micromachining process.

Listeria monocytogenes isolated from cold-smoked fish products in Osaka City, Japan

Listeria monocytogenes contamination of ready-to-eat seafood products commercially available in Osaka was examined between 1999 and 2000. L. monocytogenes was isolated from 12 (13%) of the 95 products tested. All positive samples were from cold-smoked fish with 9 being obtained during the summer. Thirteen isolates of L. monocytogenes were typed by pulsed-field gel electrophoresis (PFGE) and polymerase chain reaction (PCR)-based typing methods. Isolates of the same serotype originating from the same manufacturer gave similar DNA profiles, irrespective of the type of sample or date of isolation. The finding suggest that persistent strains in each manufacturing facility proliferate during the summer and contaminate products during manufacturing processes.

The novel mutation K87E in ribosomal protein S12 enhances protein synthesis activity during the late growth phase in Escherichia coli

Resistance to streptomycin in bacterial cells often results from a mutation in the rpsL gene that encodes the ribosomal protein S12. We found that a particular rpsL mutation (K87E), newly identified in Escherichia coli, causes aberrant protein synthesis activity late in the growth phase. While protein synthesis decreased with age in cells in the wild-type strain, it was sustained at a high level in the mutant, as determined using living cells. This was confirmed using an in vitro protein synthesis system with poly(U) and natural mRNAs (GFP mRNA and CAT mRNA). Other classical rpsL mutations (K42N and K42T) tested did not show such an effect, indicating that this novel characteristic is typical of ribosomes bearing the K87E mutant form of S12, although the K87E mutation conferred the streptomycin resistance and error-restrictive phenotypes also seen with the K42N and K42T mutations. The K87E (but not K42N or K42T) mutant ribosomes exhibited increased stability of the 70S complex in the presence of low concentrations of magnesium. We propose that the aberrant activation of protein synthesis at the late growth phase is caused by the increased stability of the ribosome.

A rifampicin resistance mutation in the rpoB gene confers ppGpp-independent antibiotic production in Streptomyces coelicolor A3(2)

In Streptomyces coelicolor A3(2), deletion of relA or a specific mutation in rplK ( relC) results in an inability to synthesize ppGpp (guanosine 5'-diphosphate 3'-diphosphate) and impairs production of actinorhodin. We have found that certain rifampicin-resistant ( rif) mutants isolated from either relA or relC strains regain the ability to produce actinorhodin at the same level as the wild-type strain, although their capacity to synthesize ppGpp is unchanged. These rif mutants were found to have a missense mutation in the rpoB gene that encodes the RNA polymerase beta-subunit. This rpoB mutation was shown to be responsible for the observed changes in phenotype, as demonstrated by gene replacement experiments. Gene expression analysis revealed that the restoration of actinorhodin production in both relA and relC strains is accompanied by increased expression of the pathway-specific regulator gene actII-ORF4, which is normally decreased in the rel mutants. In addition to the restoration of antibiotic production, the rif mutants also exhibited a lower rate of RNA synthesis compared to the parental strain when grown in a rich medium, suggesting that these mutant RNA polymerases behave like "stringent" RNA polymerases. These results indicate that rif mutations can alter gene expression patterns independently of ppGpp. We propose that RNA polymerases carrying particular rif mutations in the beta-subunit can functionally mimic the modification induced by binding of ppGpp.

The inhibitory effect of the autoantigen La on in vitro 3' processing of mammalian precursor tRNAs

Mammalian tRNA 3' processing endoribonuclease (3' tRNase) can remove a 3' trailer from various precursor (pre)-tRNAs. We investigated what effect the autoantigen La has on 3' processing, since the La protein is known to bind to a 3'-terminal uridine tract of pre-tRNAs. We tested sixteen different pre-tRNA(Arg) substrates containing various 3' trailers with or without a 5' leader sequence for in vitro processing by pig 3' tRNase, and for gel-retardation in the presence or absence of human La protein. The R-TUUU series consists of four pre-tRNAs containing 6, 8, 11 and 15 nt 3' trailers ending with UUU and no 5' leader, while the R-TAGC series consists of the same four pre-tRNAs as R-TUUU except that the terminal sequence is AGC. The R-6LTUUU and R-6LTAGC series are derived from R-TUUU and R-TAGC, respectively, by adding a 6 nt 5' leader. La differentially inhibited their processing and bound to the pre-tRNAs; the 50 % inhibitory concentrations for the R-TUUU, R-TAGC, R-6LTUUU, and R-6LTAGC series were 82 to >850, >850, 2 to 292 and 573 to 785 nM, respectively, and the dissociation constants were 10 to 840, >850, 3 to 203 and 155 to 520 nM, respectively. These results indicate that both the terminal sequence UUU and the 5' leader contribute to more severe inhibition of 3' processing via tighter interaction with La. With respect to the R-TUUU and R-6LTUUU series, on the whole, the La inhibition was enhanced as the 3' trailer lengths decreased. Taken together, our results suggest that the La protein sterically hinders 3' tRNase from binding a pre-tRNA molecule probably near the cleavage site.

Molecular and functional analyses of the gene (eshA) encoding the 52-kilodalton protein of Streptomyces coelicolor A3(2) required for antibiotic production

Analysis of proteins recovered in the S100 precipitate fraction of Streptomyces griseus after ultracentrifugation led to the identification of a 52-kDa protein which is produced during the late growth phase. The gene (eshA) which codes for this protein was cloned from S. griseus, and then its homologue was cloned from Streptomyces coelicolor A3(2). The protein was deduced to be 471 amino acids in length. The protein EshA is characterized by a central region that shows homology to the eukaryotic-type cyclic nucleotide-binding domains. Significant homology was also found to MMPI in Mycobacterium leprae, a major antigenic protein to humans. The eshA gene mapped near the chromosome end and was not essential for viability, as demonstrated by gene disruption experiments, but its disruption resulted in the abolishment of an antibiotic (actinorhodin but not undecylprodigiosin) production. Aerial mycelium was produced as abundantly as by the parent strain. Expression analysis of the EshA protein by Western blotting revealed that EshA is present only in late-growth-phase cells. The eshA gene was transcribed just preceding intracellular accumulation of the EshA protein, as determined by S1 nuclease protection, indicating that EshA expression is regulated at the transcription level. The expression of EshA was unaffected by introduction of the relA mutation, which blocks ppGpp synthesis.

Sound-evoked myogenic potentials and responses with 3-ms latency in auditory brainstem response

OBJECTIVES

The vestibular-evoked myogenic potential (VEMP) has shed new light on vestibular testing. A large negative deflection with a 3-ms latency within the auditory brainstem response (ABR) has been reported in some patients with deafness. This negative deflection has been termed the N3 potential and it is assumed to be a vestibular-evoked potential. This study investigated the relationship between the VEMP and the N3 potential.

STUDY DESIGN

Prospective evaluation of the VEMP and the N3 potential in 21 patients.

METHODS

The oto-neurological tests, including caloric test, hearing sensitivity test, VEMP, and ABR, were performed and data were analyzed.

RESULTS

The average hearing threshold ranged from 65 to above 110 dB, which includes 9 (37.5%) totally deaf ears. The N3 potentials were recorded in 10 (41.7%) ears. A normal VEMP was detected in 16 (66.7%) ears. Canal paresis was observed in 11 (45.8%) ears.

CONCLUSIONS

Both the VEMP and the N3 potential appear to originate from the sacculus, but because the characteristics of these two responses are not identical, additional factors might be involved in the generation of the N3 potential.

Construction of an in vivo nonsense readthrough assay system and functional analysis of ribosomal proteins S12, S4, and S5 in Bacillus subtilis

To investigate the function of ribosomal proteins and translational factors in Bacillus subtilis, we developed an in vivo assay system to measure the level of nonsense readthrough by utilizing the LacZ-LacI system. Using the in vivo nonsense readthrough assay system which we developed, together with an in vitro poly(U)-directed cell-free translation assay system, we compared the processibility and translational accuracy of mutant ribosomes with those of the wild-type ribosome. Like Escherichia coli mutants, most S12 mutants exhibited lower frequencies of both UGA readthrough and missense error; the only exception was a mutant (in which Lys-56 was changed to Arg) which exhibited a threefold-higher frequency of readthrough than the wild-type strain. We also isolated several ribosomal ambiguity (ram) mutants from an S12 mutant. These ram mutants and the S12 mutant mentioned above (in which Lys-56 was changed to Arg) exhibited higher UGA readthrough levels. Thus, the mutation which altered Lys-56 to Arg resulted in a ram phenotype in B. subtilis. The efficacy of our in vivo nonsense readthrough assay system was demonstrated in our investigation of the function of ribosomal proteins and translational factors.

Condylar bony change and self-reported parafunctional habits in prospective orthognathic surgery patients with temporomandibular disorders

OBJECTIVE

The purpose of this study was to investigate the relationship between self-reported parafunctional habits and condylar bony change and disk displacement in orthognathic surgery patients with signs and symptoms of temporomandibular joint disorders.

STUDY DESIGN

This is a cross-sectional retrospective study of pretreatment helical computed tomography scans and questionnaires of 94 female orthognathic surgery patients.

RESULTS

Condylar bony change, unilaterally or bilaterally, was found in 56.4% of the subjects, or 43.6% of the joints. Disk displacement, unilaterally or bilaterally, was seen in 59.6% of the subjects, or 45.7% of the joints. Bruxism and clenching was significantly associated with condylar bony change and disk displacement. Subjects with 3 or more parafunctional habits showed a significantly higher rate of bilateral condylar bony change.

CONCLUSION

Our results suggest that bruxism and clenching might be related to deterioration of the temporomandibular joint and that the greater the number of parafunctional habits a subject has, the higher the risk of condylar bony change.

Novel approach for improving the productivity of antibiotic-producing strains by inducing combined resistant mutations

We developed a novel approach for improving the production of antibiotic from Streptomyces coelicolor A3(2) by inducing combined drug-resistant mutations. Mutants with enhanced (1.6- to 3-fold-higher) actinorhodin production were detected at a high frequency (5 to 10%) among isolates resistant to streptomycin (Str(r)), gentamicin (Gen(r)), or rifampin (Rif(r)), which developed spontaneously on agar plates which contained one of the three drugs. Construction of double mutants (str gen and str rif) by introducing gentamicin or rifampin resistance into an str mutant resulted in further increased (1.7- to 2.5-fold-higher) actinorhodin productivity. Likewise, triple mutants (str gen rif) thus constructed were found to have an even greater ability for producing the antibiotic, eventually generating a mutant able to produce 48 times more actinorhodin than the wild-type strain. Analysis of str mutants revealed that a point mutation occurred within the rpsL gene, which encodes the ribosomal protein S12. rif mutants were found to have a point mutation in the rpoB gene, which encodes the beta-subunit of RNA polymerase. Mutation points in gen mutants still remain unknown. These single, double, and triple mutants displayed in hierarchical order a remarkable increase in the production of ActII-ORF4, a pathway-specific regulatory protein, as determined by Western blotting analysis. This reflects the same hierarchical order observed for the increase in actinorhodin production. The superior ability of the triple mutants was demonstrated by physiological analyses under various cultural conditions. We conclude that by inducing combined drug-resistant mutations we can continuously increase the production of antibiotic in a stepwise manner. This new breeding approach could be especially effective for initially improving the production of antibiotics from wild-type strains.

Electrocochleogram after transection of vestibulo-cochlear nerve in a patient with a large acoustic neurinoma

This study reports pre- and post-operative compound action potentials (CAPs) that were recorded from a 27-year-old woman with an acoustic neurinoma. During surgery it was necessary to totally sever her vestibulo-cochlear nerve to excise a large tumor. A pure tone audiogram changed to the scale-out pattern immediately after operation. However, CAP, the waveform of which was broadened, has been recorded 3 years post-operatively with a threshold elevation of 10 dB over the pre-operative threshold. This phenomenon suggests that CAP may originate from the extreme periphery of the auditory nerve within the cochlea. The broadening of the CAP was assumed to result from enhancement of the negative summating potential included in the CAP. We studied the effect of preceding stimulus on CAP using paired click stimuli pre- and post-operatively. A reduction of CAP amplitude in response to the second click of paired clicks was markedly suppressed in the inter-click interval between 3 and 80 ms post-operatively. We speculate that depletion of adaptation induced the abnormal CAP recovery described above and that the lateral efferent nerve system was involved in abnormal CAP adaptation with transection of the vestibulo-cochlear nerve in this case.

[The clinical application and modification of the Quad Helix appliance]

OBJECTIVE

The aims of this study are to investigate the working mechanism, the characteristics, the clinical application and the suggested modification of the Quad Helix appliance.

METHODS

A 7-year-old, female patient with Pierre-Rokin syndrome, who was preformed with palatorrhaphy at 21-month-old treated by using a Quad Helix appliance for one year.

RESULTS

After one-year treatment, the wide between the maxillary first molars increased 9.65 mm, and the wide between maxillary canines increased 5.20 mm. The wide between the mandibular first molars also increased 3.60 mm, however the wide between mandibular canines decreased 5.20 mm.

CONCLUSION

The Quad-helix appears to be a successful Orthodontic appliance to expand the narrow maxillary or mandibular arches.

Variance of vestibular-evoked myogenic potentials

OBJECTIVES/HYPOTHESIS

Vestibular-evoked myogenic potential (VEMP) has been thought to originate from sacculus. The variance of this potential and the effectiveness of the adjustments of pInII amplitudes using average muscle tonus of ipsilateral sternocleidomastoid muscle were evaluated. In addition, clinical application of VEMP was examined in patients with acoustic tumors (ATs) and vestibular neurolabyrinthitis (VNL).

STUDY DESIGN

Prospective evaluation of the VEMP in 18 normal volunteers and 6 patients.

METHODS

Variance and left-right difference of each parameter, including pI latency, nII latency, pInII amplitude, and threshold, was analyzed. Input-output function of pInII amplitude was evaluated. Average muscle tonus was calculated in 20 ears and applied for adjustment of pInII amplitude. Sensitivity of each parameter of VEMP was examined in 3 patients with ATs and 3 patients with VNL.

RESULTS

VEMP was present in all 36 ears of 18 control subjects. Thresholds of VEMP for normal subjects were 80 to 95 dB normal hearing level (nHL). The muscle tonus affected pInII amplitude significantly; however, no statistically significant improvement was observed in test-retest investigation after adjustment using muscle tonus. The threshold of the affected side was elevated compared with the non-affected side in all patients with ATs, whereas 2 of 3 patients showed normal pInII-ratio. One patient with VNL presented normal VEMP, whereas 2 patients presented no VEMP to the highest stimulus intensity.

CONCLUSIONS

Interaural difference of thresholds might be the most useful parameters. Adjustment using average muscle tonus is not necessary when the subject is able to get sufficient muscle tonus.

Complete nucleotide sequence of the cytochrome b gene of channel catfish Ictalurus punctatus and comparison of sequence homology among channel catfish and other fishes

To clarify the phylogenic relationship of channel catfish with other fishes, the cytochrome b (Cyt b) gene of the catfish was cloned and sequenced. Channel catfish (Ictalurus punctatus) belonging to the family Ictaluridae in the order Siluriformes showed a 78.4-87.4% similarity to all but one fish of the family Cyprinidae and river loach Crossostoma lacustre of the family Balitoridae in the order Cypriniformes in which genes had already been sequenced, and a 97.2% similarity to the goldfish (Carassius auratus) belonging to the family Cyprinidae. Within the family Cyprinidae, a 78.8-89.2% similarity to one another was recorded. In addition, the similarity rate between the family Cyprinidae and the family Balitoridae reached a value of 77.8-79.9% in the order Cypriniformes. Furthermore, in an unrooted phylogenetic tree consisting of four branches among eight fishes, channel catfish and goldfish appeared in the same branch. These results suggested that the Cyt b gene of the channel catfish in the order Siluriformes was closely related to that of a goldfish in the order Cypriniformes. The results were not agreement with the morphological classification. Genetic reclassification of the fishes may be necessary to identify the ancestor. This is the first report on the cloning and complete sequencing the Cyt b gene of the channel catfish which may contribute to the genetic reclassification of catfishes belonging to the order Siluriformes.

Giant negative T waves during interferon therapy in a patient with chronic hepatitis C

Interferon-alpha (IFN-alpha) has been widely used for treatment of chronic hepatitis C in Japan. In general, cardiovascular adverse reactions are rare in association with IFN-alpha therapy. Here, a 64-year-old man with chronic active hepatitis C complained of fatigue, palpitation and depression, and developed atrial fibrillation with prominent negative T waves during IFN-alpha therapy. Echocardiogram showed septal and apical hypertrophy. Three days after discontinuation of IFN-alpha, subjective symptoms and atrial fibrillation subsided. It is unclear whether or not IFN-alpha induced the giant negative T waves with apical hypertrophy. We might observe the developing course of hepatitis C virus (HCV)-related myocardial hypertrophy by chance. Cardiovascular toxicity should be carefully monitored during IFN-alpha therapy even in patients with minor cardiac disease, such as premature ventricular contracture (PVC) and mild hypertension.

Study on free radicals and pancreatic fibrosis--pancreatic fibrosis induced by repeated injections of superoxide dismutase inhibitor

The exact mechanisms of the development of pancreatic fibrosis are still unknown. To clarify the relationship between pancreatic fibrosis and free radicals, the effect of the administration of a superoxide dismutase (SOD) inhibitor, diethyldithiocarbamate (DDC), on pancreatic fibrosis in rats was studied. A single intraperitoneal injection of 500 mg/kg of DDC significantly reduced SOD activity and significantly increased lipid peroxidation products in the pancreas, showing no histologic changes of inflammation or necrosis. Repeated administration of 500 mg/kg DDC, twice a week, caused inter- and intralobular fibrosis with atrophy of acinar cells in the pancreas for at least 2 weeks without fibrosis of the liver and kidney. Administration of allopurinol showed preventive effects against DDC-induced pancreatic fibrosis. In conclusion, repeated administration of DDC, which caused pancreatic fibrosis, is a new experimental model of pancreatic fibrosis from the viewpoint of oxidative stress.

Multinucleated giant cells in submucosal layer of human urinary bladder: an immunohistochemical and electron microscopic study

Multinucleated giant cells (MGC) detected in the submucosal layer of human urinary bladder mainly associated with transitional cell carcinoma were examined immunohistochemically and ultrastructurally. The cases examined totaled 29, namely 14 cases with transitional cell carcinoma and another 15 cases mostly with malignancy in other organs. Histologically, MGC were smooth, irregular or dendritic in shape, and tended to increase in number in the vicinity of cancer or marked inflammation. They were consistently positive for not only vimentin, but also MB-2, and CD34, and were mostly positive for proliferating cell nuclear antigen (PCNA), but not MIB-1 (Ki-67) and HLA-DRalpha antigens. On occasion, antibodies to alpha-smooth muscle actin (alpha-SMA), muscle actin (M-actin), CD68 (KP-1) and alpha subunit of S-100 protein also yielded positive reactions. Interestingly, aggregated short bulbous processes were ultrastructurally observed on their surface in parts. These findings suggested that MGC in the submucosal layer of human urinary bladder were MB-2 and CD34-positive multipotential mesenchymal cells with no mitotic activity expressing fibroblastic (vimentin), myofibroblastic (alpha-SMA), or histiocytic (CD68) markers mostly in the vicinity of malignancy, and that these MGC were formed by fusion of mononuclear cells expressing identical markers with those of MGC. Further investigations are needed to clarify the exact function of MGC in human urinary bladder.

Clinical evaluation of cholecystokinin-A- receptor antagonist (loxiglumide) for the treatment of acute pancreatitis. A preliminary clinical trial. Study Group of Loxiglumide in Japan

The therapeutic effects of loxiglumide on human acute pancreatitis was investigated in 104 Japanese institutes from October 1992 to March 1994. Acute pancreatitis was diagnosed by the Japanese Criteria of Acute Pancreatitis. Soon after the diagnosis was made, one of three doses of loxiglumide (100, 300 and 500 mg/day) were injected intravenously twice a day for 14 days. The efficacy of the treatment was evaluated by clinical signs, physical signs, and biochemical findings. 189 patients were included in this trial. The clinical signs, such as abdominal pain, disappeared in 20% of the patients on the 1st day after treatment, and the rate of improvements increased thereafter. Physical signs also improved. Serum amylase levels returned to normal within 3 days after treatment, and serum lipase showed almost the same changes as serum amylase levels, but serum lipase levels in the high-dose group (500 mg/day) returned to normal more quickly compared with the other two doses. It is concluded that the cholecystokinin A receptor antagonist, loxiglumide, may become a useful drug in the treatment of acute pancreatitis in man, although more detailed investigations are needed.

Polyketide synthase gene coupled to the peptide synthetase module involved in the biosynthesis of the cyclic heptapeptide microcystin

The peptide synthetase gene operon, which consists of mcyA, mcyB, and mcyC, for the activation and incorporation of the five amino acid constituents of microcystin has been identified [T. Nishizawa et al. (1999) J. Biochem. 126, 520-529]. By sequencing an additional 34 kb of DNA from microcystin-producing Microcystis aeruginosa K-139, we identified the residual microcystin synthetase gene operon, which consists of mcyD, mcyE, mcyF, and mcyG, in the opposite orientation to the mcyABC operon. McyD consisted of two polyketide synthase modules, and McyE contained a polyketide synthase module at the N-terminus and a peptide synthetase module at the C-terminus. McyF was found to exhibit similarity to amino acid racemase. McyG consisted of a peptide synthetase module at the N-terminus and a polyketide synthase at the C-terminus. The microcystin synthetase gene cluster was conserved in another microcystin-producing strain, Microcystis sp. S-70, which produces Microcystin-LR, -RR, and -YR. Insertional mutagenesis of mcyA, mcyD, or mcyE in Microcystis sp. S-70 abolished microcystin production. In conclusion, the mcyDEFG operon is presumed to be responsible for 3-amino-9-methoxy-2,6, 8-trimethyl-10-phenyldeca-4,6-dienoic acid (Adda) biosynthesis, and the incorporation of Adda and glutamic acid into the microcystin molecule.

Presence of 22-kDa protein reacting with sera in piglets experimentally infected with Brachyspira hyodysenteriae

In order to examine the effect of spectinomycin on outbreaks of swine dysentery, experimental infection of piglets with Brachyspira hyodysenteriae was carried out. Feed with and without spectinomycin (SP) was given to each piglet ad libitum and the susceptibility of the piglets to infection with B. hyodysenteriae was compared between SP-treated and untreated piglets. The results showed that the SP-treated piglets did not display clinical signs of swine dysentery unlike the untreated piglets. The sera obtained from these piglets were examined by the microscopic agglutination test and antibodies to B. hyodysenteriae in both groups of experimentally infected piglets were detected and the reaction was serogroup-specific. The agglutination titers were very high in the untreated piglets with dysentery while the titers in the SP-treated piglets were lower than those in the untreated piglets. In addition, the immunoblotting technique was applied and the results demonstrated that 22- and 17-kDa proteins in strain ATCC 31212 (serogroup B) reacted strongly with the sera from the untreated piglets but not with the sera from the SP-treated piglets. The 22- and 17-kDa proteins also reacted with strain ATCC 27164 (serogroup A) which belongs to a different serogroup. The 22- and 17-kDa proteins were also confirmed in six other strains of B. hyodysenteriae which belong to six different serogroups. These proteins were sensitive to proteinase K. These results indicate that the 22- and 17-kDa proteins are common to eight strains of B. hyodysenteriae which differ serologically from each other.

The Ruffini ending as the primary mechanoreceptor in the periodontal ligament: its morphology, cytochemical features, regeneration, and development

The periodontal ligament receives a rich sensory nerve supply and contains many nociceptors and mechanoreceptors. Although its various kinds of mechanoreceptors have been reported in the past, only recently have studies revealed that the Ruffini endings--categorized as low-threshold, slowly adapting, type II mechanoreceptors--are the primary mechanoreceptors in the periodontal ligament. The periodontal Ruffini endings display dendritic ramifications with expanded terminal buttons and, furthermore, are ultrastructurally characterized by expanded axon terminals filled with many mitochondria and by an association with terminal or lamellar Schwann cells. The axon terminals of the periodontal Ruffini endings have finger-like projections called axonal spines or microspikes, which extend into the surrounding tissue to detect the deformation of collagen fibers. The functional basis of the periodontal Ruffini endings has been analyzed by histochemical techniques. Histochemically, the axon terminals are reactive for cytochrome oxidase activity, and the terminal Schwann cells have both non-specific cholinesterase and acid phosphatase activity. On the other hand, many investigations have suggested that the Ruffini endings have a high potential for neuroplasticity. For example, immunoreactivity for p75-NGFR (low-affinity nerve growth factor receptor) and GAP-43 (growth-associated protein-43), both of which play important roles in nerve regeneration/development processes, have been reported in the periodontal Ruffini endings, even in adult animals (though these proteins are usually repressed or down-regulated in mature neurons). Furthermore, in experimental studies on nerve injury to the inferior alveolar nerve, the degeneration of Ruffini endings takes place immediately after nerve injury, with regeneration beginning from 3 to 5 days later, and the distribution and terminal morphology returning to almost normal at around 14 days. During regeneration, some regenerating Ruffini endings expressed neuropeptide Y, which is rarely observed in normal animals. On the other hand, the periodontal Ruffini endings show stage-specific configurations which are closely related to tooth eruption and the addition of occlusal forces to the tooth during postnatal development, suggesting that mechanical stimuli due to tooth eruption and occlusion are a prerequisite for the differentiation and maturation of the periodontal Ruffini endings. Further investigations are needed to clarify the involvement of growth factors in the molecular mechanisms of the development and regeneration processes of the Ruffini endings.

Functional coupling of Ca(2+) channels to ryanodine receptors at presynaptic terminals. Amplification of exocytosis and plasticity

Ca(2+)-induced Ca(2+) release (CICR) enhances a variety of cellular Ca(2+) signaling and functions. How CICR affects impulse-evoked transmitter release is unknown. At frog motor nerve terminals, repetitive Ca(2+) entries slowly prime and subsequently activate the mechanism of CICR via ryanodine receptors and asynchronous exocytosis of transmitters. Further Ca(2+) entry inactivates the CICR mechanism and the absence of Ca(2+) entry for >1 min results in its slow depriming. We now report here that the activation of this unique CICR markedly enhances impulse-evoked exocytosis of transmitter. The conditioning nerve stimulation (10-20 Hz, 2-10 min) that primes the CICR mechanism produced the marked enhancement of the amplitude and quantal content of end-plate potentials (EPPs) that decayed double exponentially with time constants of 1.85 and 10 min. The enhancement was blocked by inhibitors of ryanodine receptors and was accompanied by a slight prolongation of the peak times of EPP and the end-plate currents estimated from deconvolution of EPP. The conditioning nerve stimulation also enhanced single impulse- and tetanus-induced rises in intracellular Ca(2+) in the terminals with little change in time course. There was no change in the rate of growth of the amplitudes of EPPs in a short train after the conditioning stimulation. On the other hand, the augmentation and potentiation of EPP were enhanced, and then decreased in parallel with changes in intraterminal Ca(2+) during repetition of tetani. The results suggest that ryanodine receptors exist close to voltage-gated Ca(2+) channels in the presynaptic terminals and amplify the impulse-evoked exocytosis and its plasticity via CICR after Ca(2+)-dependent priming.