Reappraisal of the taxonomy of Streptococcus suis serotypes 20, 22 and 26: Streptococcus parasuis sp. nov

In order to clarify the taxonomic position of serotypes 20, 22 and 26 of Streptococcus suis , biochemical and molecular genetic studies were performed on isolates (SUT-7, SUT-286T, SUT-319, SUT-328 and SUT-380) reacted with specific antisera of serotypes 20, 22 or 26 from the saliva of healthy pigs as well as reference strains of serotypes 20, 22 and 26. Comparative recN gene sequencing showed high genetic relatedness among our isolates, but marked differences from the type strain S. suis NCTC 10234T, i.e. 74.8–75.7 % sequence similarity. The genomic relatedness between the isolates and other strains of species of the genus Streptococcus , including S. suis, was calculated using the average nucleotide identity values of whole genome sequences, which indicated that serotypes 20, 22 and 26 should be removed taxonomically from S. suis and treated as a novel genomic species. Comparative sequence analysis revealed 99.0–100 % sequence similarities for the 16S rRNA genes between the reference strains of serotypes 20, 22 and 26, and our isolates. Isolate STU-286T had relatively high 16S rRNA gene sequence similarity with S. suis NCTC 10234T (98.8 %). SUT-286T could be distinguished from S. suis and other closely related species of the genus Streptococcus using biochemical tests. Due to its phylogenetic and phenotypic similarities to S. suis we propose naming the novel species Streptococcus parasuis sp. nov., with SUT-286T ( = JCM 30273T = DSM 29126T) as the type strain.

Genetic and phenotypic comparison of Nocardia seriolae isolated from fish in Japan

The phenotypic and genetic characterizations of 58 isolates of the fish pathogen Nocardia seriolae, from amberjack, Seriolae dumerili, yellowtail, Seriola quinqueradiata, Japanese flounder, Paralichthys olivaceus, and chub mackerel, Scomber japonicus, in Japan from 1970-2005, were examined to investigate the epidemiological relationship between isolates. The phenotypic and genetic characterizations were determined by alpha-glucosidase activity and biased sinusoidal field gel electrophoresis (BSFGE) analysis, respectively. There was no alpha-glucosidase activity in strains isolated from 2000-05 (n = 50) with a few exceptions (n = 3), while all strains isolated from 1970-90 (n = 8) were positive. In BSFGE analysis, digestions with restriction enzymes Xba I and Ase I produced 15 and 16 restriction patterns, respectively. All restriction patterns obtained from 50 strains isolated during 2000-05 were unrelated to those obtained from eight strains isolated during 1970-90, with the exception of two strains isolated during recent outbreaks. Based on the phenotypic and genetic characterizations, recent outbreaks of nocardiosis in Japan are suggested to be epidemiologically unrelated to earlier outbreaks in Japan. Although a low genetic relationship was observed in the restriction pattern between recent and earlier isolates, identity was confirmed between these groups of isolates because five representative strains showed 99.9% homology with N. seriolae ATCC43993(T) in the 16S rRNA sequence.

Partial sequencing of sodA gene and its application to identification of Streptococcus dysgalactiae subsp. dysgalactiae isolated from farmed fish

AIMS

To investigate the difference between Lancefield group C Streptococcus dysgalactiae (GCSD) strains isolated from diseased fish and animals by sequencing and phylogenetic analysis of the sodA gene.

METHODS AND RESULTS

The sodA gene of Strep. dysgalactiae strains isolated from fish and animals were amplified and its nucleotide sequences were determined. Although 100% sequence identity was observed among fish GCSD strains, the determined sequences from animal isolates showed variations against fish isolate sequences. Thus, all fish GCSD strains were clearly separated from the GCSD strains of other origin by using phylogenetic tree analysis. In addition, the original primer set was designed based on the determined sequences for specifically amplify the sodA gene of fish GCSD strains. The primer set yield amplification products from only fish GCSD strains.

CONCLUSIONS

By sequencing analysis of the sodA gene, the genetic divergence between Strep. dysgalactiae strains isolated from fish and mammals was demonstrated. Moreover, an original oligonucletide primer set, which could simply detect the genotype of fish GCSD strains was designed.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study shows that Strep. dysgalactiae isolated from diseased fish could be distinguished from conventional GCSD strains by the difference in the sequence of the sodA gene.

Quantitative determination of radio-opacity: equivalence of digital and film X-ray systems

OBJECTIVES

To evaluate the equivalence of a digital X-ray system (DenOptix) to conventional X-ray film in terms of the measured radio-opacity of known filled-resin materials and the suitability of attenuation coefficient for radio-opacity determination.

METHODS

Discs of five thicknesses (0.5-2.5mm) and step-wedges of each of three composite materials of nominal aluminum-equivalence of 50%, 200% and 450% were used. X-ray images of a set of discs (or step-wedge), an aluminum step-wedge, and a lead block were taken at 65 kV and 10 mA at a focus-film distance of 400 mm for 0.15s and 1.6s using an X-ray film or imaging plate. Radio-opacity was determined as equivalent aluminum thickness and attenuation coefficient. The logarithm of the individual optical density or gray scale value, corrected for background, was plotted against thickness, and the attenuation coefficient determined from the slope. The method of ISO 4049 was used for equivalent aluminum thickness.

RESULTS

The equivalent aluminum thickness method is not suitable for materials of low radio-opacity, while the attenuation coefficient method could be used for all without difficulty. The digital system gave attenuation coefficients of greater precision than did film, but the use of automatic gain control (AGC) distorted the outcome unusably.

CONCLUSION

Attenuation coefficient is a more precise and generally applicable approach to the determination of radio-opacity. The digital system was equivalent to film but with less noise. The use of AGC is inappropriate for such determinations.

Characterization of Lancefield group C Streptococcus dysgalactiae isolated from farmed fish

A Lancefield group C streptococcal (GCS) infection caused by Streptococcus dysgalactiae that is characterized by severe necrotic lesions of the caudal peduncle has been an increasing cause of mortality in farmed fish such as amberjack, Seriola dumerili, and yellowtail, Seriola quinqueradiata, in the southern part of Kyushu, Japan. In this study, enzymatic profiles of GCS strains from fish and mammals were investigated using the API ZYM system, and genotypic characterization of GCS strains was performed using biased sinusoidal field gel electrophoresis (BSFGE). The partial sequence of the 16S-23S rDNA intergenic spacer region of the GCS strain isolates from fish and mammals was also compared. The API ZYM test indicated that it is difficult to differentiate isolates of S. dysgalactiae from fish and animals based on enzymological variations. In the BSFGE analysis, the macrorestriction profiles, which were obtained using SmaI or ApaI as a restriction enzyme, revealed variations between the fish and animal isolates. The partial sequence of the 16S-23S rDNA intergenic spacer region of all the tested fish isolates differed from all mammalian isolates in one or two nucleotides. The possibility of a clonal expansion of S. dysgalactiae strains in farmed fish was also suggested by the BSFGE profiles of fish isolates.

Lancefield group C Streptococcus dysgalactiae infection responsible for fish mortalities in Japan

A Lancefield serological group C Streptococcus sp. was isolated from cultured amberjack, Seriola dumerili Risso, and yellowtail, Seriola quinqueradiata Temminck and Schlegel, immunized with Lactococcus garvieae commercial vaccines in Japan. The isolated bacteria were Gram-positive cocci, auto-aggregating in saline, morphologically long chains in growth medium, catalase negative and alpha-haemolytic on blood agar. An almost complete gene sequence of the 16S rDNA of two isolates was determined and compared with that of bacterial strains in the database. The isolates were identified as Streptococcus dysgalactiae based on the results of the 16S rDNA sequence, the bacteriological properties and the Lancefield serological grouping. Oligonucleotide primers specifically designed for the 16S-23S rDNA intergenic spacer region of S. dysgalactiae amplified a gene from all the fish isolates, as well as the type strains alpha-haemolytic S. dysgalactiae subsp. dysgalactiae ATCC430738 and beta-haemolytic S. dysgalactiae subsp. equisimilis ATCC35666, but not those of S. equi ATCC33398, Lactococcus garvieae ATCC43921 and L. garvieae KG9408. The severe necrotic lesions of the caudal peduncle seen in experimentally infected fish were similar to those seen in naturally infected fish.

Suitability of a shear punch test for dental restorative materials

OBJECTIVE

The aim of the study was to evaluate the suitability of a shear punch test for determining the mechanical properties of dental restorative materials. The method was evaluated by measuring and comparing the shear punch strength of seven different restorative materials, that is amalgam, composite resin, compomer, composite containing pre-reacted glass ionomer filler, resin modified glass ionomer, glass ionomer and polycarboxylate cement.

METHOD

The effects of specimen restraining conditions, specimen thickness and test speed on the shear punch strength were evaluated using polycarboxylate cement and two different equipment set-ups. Using the preferred testing regime as determined in the preliminary experiments, the shear punch strength of seven different materials were measured and compared. Twenty disc specimens, 0.5mm thick and 10mm diameter, were prepared for each material, restrained within the test equipment and tested at a speed of 1.0mm/min.

RESULTS

The shear punch strength increased as the torque used for restraining a specimen was increased. There was no difference in shear punch strength for specimens of different thickness. The greatest shear punch strength was obtained at the test speed of 1.0mm/min. The shear punch strength values decreased in the order composite>composite containing pre-reacted glass ionomer filler>amalgam>compomer>resin-modified glass ionomer>glass ionomer>polycarboxylate. A difference in the shear punch strength for seven different kinds of restorative materials clearly emerged. Specimen fracture occurred by circumferential cracking for the shear-punch test. However, for some glass ionomer and amalgam specimens radial cracking was also observed.

SIGNIFICANCE

This study suggests that the simple test described is suitable for standardization purposes.

Effect of mixing methods on the compressive strength of glass ionomer cements

OBJECTIVE

The purpose of the study was to evaluate the effect of the mixing method on the compressive strength and porosity of dental glass ionomer cements.

METHOD

Five glass ionomer cements were chosen for use in the study. Two were hand mixed and three were encapsulated. The latter were mixed either by shaking or rotating. Following mixing by rotation some samples were centrifuged before use. The 24h compressive strength was determined for each cement/mixing regime combination and fracture surfaces were examined using SEM.

RESULTS

The mixing method had a significant effect on compressive strength (P<0.05). For the luting/lining cement, hand mixing produced a significantly greater compressive strength (P<0.05). For the restorative cement, there were only small differences between specimens mixed by different methods and hand mixing gave a significantly lower compressive strength than mixing by rotation followed by centrifuging (P<0.05). Porosity was incorporated in all samples and low values of compressive strength were associated with larger pores.

SIGNIFICANCE

The strength of glass ionomer cements is affected by incorporated porosity and this is dependent on the method of mixing. For some cements hand mixing is favoured in order to reduce porosity and increase strength but this is not generally applicable to all cements.

A simple acid erosion test for dental water-based cements

OBJECTIVE

The aim of the study was to evaluate a new erosion test for dental cements that has been developed as an alternative to the impinging jet erosion test used in current standards. The method was evaluated by measuring and comparing the extent of the erosion of three different types of dental cement.

METHODS

The erosion of three different types of cement; zinc phosphate, polycarboxylate and glass ionomer, were evaluated by measuring the depth loss of the cement placed in a cylindrical cavity in PMMA sheet after immersed in lactic acid solution (pH 2.74) or lactic acid/sodium lactate buffer solution (pH 2.74). The depth loss was measured by a dial gauge. Changes in the pH of the eroding solutions were monitored. Identical specimens were immersed in distilled water and the degree of hygroscopic expansion was also confirmed.

RESULTS

Depth loss and pH increased with increasing immersion period. The depth losses of all cements were considerably more in the buffer solution than in the acid solution. A difference in the eroded depth for three different kinds of cements clearly emerged. The depth loss for polycarboxylate was more than that for zinc phosphate, which was more than that for glass ionomer. Although hygroscopic expansion was observed for glass ionomer, the value after 24h immersion was negligible compared with the eroded depth.

SIGNIFICANCE

The results appear to correlate with those obtained using a jet erosion test and with published data on clinical performance. This suggests that the simpler test described here is suitable for standardization purposes.

Evaluation of the amount of residual monomer on UDMA-based resins by FTIR

The purpose of this study was to establish a method using FTIR to evaluate the polymerization characteristics of UDMA-based resins. Three kinds of experimental UDMA-based resins were prepared with various molar fractions. IR spectra of the cured film specimens were measured with FTIR before and after extracting residual monomer from each specimen by MeOH. From the IR spectra, the changes in the number of double bonds were measured, with the NH absorbance peak as an internal standard, and the amounts of residual monomers (RM) were calculated. The MeOH-immersed specimens were analyzed by HPLC. The RM measured by FTIR were compared with those measured by HPLC. The RM measured by HPLC were more than those by FTIR. Since these differences could be due to the difference in the area measured, this FTIR estimation method of residual monomers in cured resins using the NH absorbance peak as an internal standard could be an appropriate method when the resin monomer does not contain aromatic compounds.

Effect of light wavelength on polymerization of light-cured resins

Experimental light-cured composite resins were exposed to a narrow-band light at a constant quantum number using a narrow-band interference filter. The IR spectra of the cured resin specimens were measured before and after extraction of residual monomers. Degree of conversion (DC) and polymerization conversion (PC) were calculated from these IR spectra. The light in 410-550 nm could be polymerized. With a brief exposure (5 s), DC and PC were affected by the wavelength. The effect of wavelength between 410 and 490 nm decreased with increasing duration of exposure. The most efficient wavelength was 470 nm and the most adequate wavelength was in the 450-490 nm wavelength range. The absorbance of camphorquinone strongly affected polymerization, especially during the initial stage. However, from the relationship between DC or PC and exposure energy, polymerization depended not only on the wavelength of the light, but also on the exposure energy.

Properties of magnetically attractive experimental resin composites

SUS444 stainless steel filled chemically cured resin composites that can attract magnet were fabricated. The filler was treated with various concentrations of silane. The experimental composite was easy to handle and showed a good shelf life. The maximal properties obtained are as follows; The attraction force to a magnetic attachment was 1/3-1/4 lower than the commercially available magnet-keeper system for dental magnetic attachment. Flexural strength and Knoop hardness of the composite were 76MPa (7.7 kgf/mm2) and 64 KHN. These values were lower than the commercially available chemically cured composite used as a reference. Eluted metal from the composite in 1% lactic acid solution for 7 days showed 0.7 mg/cm2, but in 0.9% NaCl solution for 7 days, it could not be detected.

Effect of light intensity on polymerization of light-cured composite resins

The depths of cure and the distributions of degree of conversion (DC), polymerization conversion (PC) and percent pendant double bonds (PDB) of light-cured composite resins cured under various intensities of light were investigated. When the total amount of exposure, represented by the product of the light intensity and the irradiation time, was kept constant, each of the depth of cure and the distributions of DC, PC and PDB were the same for each material regardless of the light intensity and irradiation time. The depth of cure could be expressed as a logarithmic function of the total amount of exposure. From regression analysis, the attenuation coefficient and the critical total amount of exposure capable of initiating polymerization of each composite resin could be determined.

[An elderly case of thrombotic thrombocytopenic purpura]

A 78-year-old woman was admitted to our hospital because of disorientation and fever on January 21, 1992. Two days before admission she experienced vomiting, anorexia and general malaise. Laboratory examinations on admission disclosed a hemoglobin level of 11.1 g/dl and a platelet count of 8,000/microliters. The peripheral blood smear revealed anisocytosis with numerous schistocytes and poikilocytes. Polychromatophilic and nucleated red blood cells were also seen, and the reticulocyte count was 38/1000. Her serum lactate dehydrogenase (LDH) value was 2,977 WU and the total serum bilirubin level was 3.5 mg/dl with 2.7 mg/dl indirect reacting fraction. Serum creatinine was 4.7 mg/dl. Her consciousness became semicomatose after a systemic seizure which lasted approximately 15 seconds and her hemoglobin level decreased to 8.5 g/dl on hospital day 2. Therefore, we diagnosed her as having thrombotic thrombocytopenic purpura (TTP) because of the presence of all 5 features, that is, thrombocytopenia, microangiopathic hemolytic anemia, fluctuating neurologic abnormalities, renal dysfunction and fever. A plasmapheresis with fresh frozen plasma (FFP) replacement was begun on that day. She was also treated with anti-platelet agents, 80 mg/day aspirin, and 300 mg/day dipyridamole. Moreover, packed red blood cells (PRC) were infused. While also receiving diphenylhydantoin and phenobarbital to prevent convulsions, status epilepticus developed on day 3. Because of inhibited spontaneous respiration which was an adverse effect derived from diazepam and sodium thiamylal administered intravenously to treat the status epilepticus, an artificial respiration was initiated.(ABSTRACT TRUNCATED AT 250 WORDS)

Residual monomer and pendant methacryloyl group in light-cured composite resins

Microareas (100 x 100 microns 2) of thin visible light-cured composite sections irradiated for 10-60 s were analyzed with a Fourier transform infrared spectrometer equipped with a microscopic unit before and after extraction of residual monomers to determine the percent unreacted double bonds (UDB) and percent pendant double bonds (PDB). The percent eluted double bonds (EDB) was calculated using these percents. Analysis was conducted at various depths along the midline from the irradiated surface to the base. There were significant differences among the tested materials at each depth in UDB, PDB and EDB percents. The percent PDB of each material remained almost constant (25-40%) to a certain depth. This depth was equivalent to 70-80% of the depth of cure for each material. The range of depths at which percent PDB was constant indicated greater than 35-40% degree of conversion. At these locations, the composites may polymerize with a high rate of crosslinking.

[Clinical characteristics of postinfarction left ventricular aneurysm with extensive calcification]

The authors experienced 4 cases of calcified postinfarction aneurysm of the left ventricle. They were all male, aged 55 to 71 (mean 64). Risk factor for coronary artery disease was only smoking in 2 patients, but there was none in the others. They had had acute anteroseptal or extensive anterior infarction at age 41-57 years (mean 49.3), and associated major cardiac events 10-22 years (mean 14.5) after acute myocardial infarction. Ventricular tachycardia, congestive heart failure and systemic thromboembolism were seen in 4, 2 and 1 patients respectively. However, none developed angina pectoris. In the 2 patients in whom signal-averaged electrocardiogram was performed, late potential was detected, so it was suspected that ventricular tachycardia could be due to reentry. Left ventricular end-diastolic pressure was elevated in all patients except one and ranged from 11 to 22 mmHg. Left ventricle was dilated in all cases and the end-diastolic volume index ranged from 143 to 503 ml/m2. The left ventricular ejection fraction ranged from 11 to 24%. However, in 2 of the 4 patients, the cardiac index was within normal limits, and evidence of congestive heart failure was absent. In 2 other patients with associated congestive heart failure, cardiac indices were 2.32, 1.56 l/min/m2 respectively. Coronary arteriogram showed a total occlusion in the left anterior descending (LAD) artery in all cases, and only the LAD artery was affected in 2 patients. In the remaining 2 patients, the right coronary arteries also were significantly stenotic or totally occluded, i.e., they had 2-vessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Kawasaki disease complicated by acute myocardial infarction due to thrombotic occlusion of coronary aneurysms 19 years after onset

A 25-year-old man with a history of Kawasaki disease from the age of 7 had acute inferior myocardial infarction. Emergency right coronary arteriogram showed successive coronary aneurysms at the proximal to middle portion of the right coronary artery, and total occlusion at the proximal segment. Intracoronary thrombolysis was performed and the right coronary artery was recanalized. On left coronary arteriography, coronary aneurysms and mild localized stenoses at the inlet and outlet of the aneurysms were found. It was suggested that the myocardial infarction was caused by thrombotic occlusion of coronary aneurysms complicated with Kawasaki disease.

Nucleosides and nucleotides. 103. 2-Alkynyladenosines: a novel class of selective adenosine A2 receptor agonists with potent antihypertensive effects

The synthesis and receptor-binding activities at A1 and A2 adenosine receptors for a series of 2-alkynyladenosines are described. The palladium-catalyzed cross-coupling reaction of 2-iodoadenosine (4a) with various terminal alkynes in the presence of bis(triphenylphosphine)palladium dichloride and cuprous iodide in N,N-dimethylformamide containing triethylamine gives 2-alkynyladenosines (5a-r). An economical synthetic method for the preparation of 9-(2,3,5-tri-O-acetyl-1-beta-D-ribofuranosyl)-6-chloro-2-iodopurine++ + (2), which is a precursor of 4a, is also included. Several transformation reactions of 2-(1-octyn-1-yl)adenosine (5e) and 2-(1-ethyn-1-yl)adenosine (9) and a similar cross-coupling reaction of 6-chloropurine derivative 11 and 8-bromoadenosine (13) with 1-octyne are also reported. Many of these 2-alkynyladenosines tested for A1 and A2 adenosine receptor binding activities in rat brain are selective for the A2 adenosine receptor. Among them, 2-(1-hexyn-1-yl)adenosine (5c) has the highest affinity for both A1 and A2 receptors with Ki values of 126.5 and 2.8 nM, respectively. The structure-activity relationship of this series of compounds including 6- or 8-alkynylpurine nucleosides and 2-alkyl- and 2-alkenyladenosines is discussed in terms of potency at both receptor subtypes. Additionally, we describe how hypotensive activity and heart rate decrease brought on by 5 and some other compounds with spontaneously hypertensive rats are proportional to the order of the potency to both A1 and A2 binding affinities. Thus, 2-alkynyladenosines are interesting and promising as antihypertensive agents that should be considered for further detailed preclinical evaluation.

A case of clinically diagnosed pure septal infarction

Interventricular septal involvement in myocardial infarction is usually associated with infarction of the left ventricular anterior free wall, as the obstruction is at the major portion of the left anterior descending coronary artery. Acute myocardial infarction with obstruction only of the first septal branch is rare. We describe here a case of pure septal infarction. The case was diagnosed by emergency coronary arteriogram (CAG). Although the patient had a large first septal branch, his global left ventricular function was preserved. Abnormal findings were localized in only septal region as determined by left ventriculography (LVG), two-dimensional echocardiography (2DE), and 99mtechnetium pyrophosphate (99m Tc-PYP) and 201thallium (201Tl) myocardial scintigraphy.

[The surface degradation of various light-cured composite resins by thermal cycling]

The durability of four commercially available light-cured composite resins was investigated by thermal cycling, GR containing inorganic fillers treated with the graft polymerization of acryl ester, LF inorganic fillers treated with a silane coupling agent, PC silanized inorganic fillers and organic composite fillers, and the MFR-type SI containing the organic composite fillers. These materials were given 10,000, 30,000 and 50,000 thermal cycles (4 degrees C-60 degrees C) and the deterioration of materials by thermal cycling was evaluated by the measurement of the mechanical properties and the SEM observations of the surface of the thermocycled materials. Compressive strength and bending elastic moduli for all materials did not change greatly by thermal cycling. However, bending strength, toothbrush abrasion resistance and surface hardness decreased with increasing number of thermal cycles between 0 and 30,000, and changed little after 30,000 cycles. The percentage of bending strength after 50,000 thermal cycles to that of the non-thermocycled sample was 75% for GR, 60% for LF, 50% for PC and 65% for SI, respectively. Deterioration of materials was observed as cracks on the surface, which generated at the interface of the filler and matrix. The cracks generated relatively earlier during thermal cycling for SI and PC which contained the organic composite filler, later for LF which contained the silanized inorganic fillers, and the number of cracks on LF were fewer than SI and PC. On the other hand, for GR, no cracks were observed even after 50,000 thermal cycles. From these results, it can be presumed that the pre-treatment of filler by the graft polymerization is more effective to improve the durability of composite resin.

Adult form acid maltase deficiency -- a case report

The case of a 26 year old man with acute respiratory difficulty was reported. Morphological and biochemical analysis of biopsied gastrocnemius muscle indicated a diagnosis of adult form acid maltase deficiency. Clinically, the most interesting point of our case was the presence of a thickening of the posterior papillary muscles and chordae without any functional disturbance, which was detected by echocardiogram. Another interesting point of our case was the existence of a sibling who died of progressive muscular dystrophy at the age of 31 years. This may raise the possibility that we are dealing with a familial type of adult form acid maltase deficiency.