COVID-19 Effects on Income and Dental Visits: A Cross-sectional Study

OBJECTIVES

In April 2020, the Japanese government declared a state of emergency owing to the outbreak of the novel coronavirus disease (COVID-19) pandemic, which resulted in reduced workforce and job losses. Furthermore, income is one of the most consistent predictors of dental visits. Therefore, this study examined the association between income changes and dental clinic visits during the COVID-19 state of emergency in Japan.

METHODS

An online, self-reported cross-sectional survey about health activities including dental visits during the first COVID-19 state of emergency was conducted in Osaka, Japan (June 23 to July 12, 2020). Among participants with toothaches, the assessment for the association between "refrained from visiting a dentist despite wanting treatment for toothache during the state of emergency (refrained treatment)" and income changes before and after the state of emergency using a multivariate Poisson regression model adjusted for sex, age, self-rated health, frequency of regular dental visits, and employment status.

RESULTS

Among 27,575 participants, 3,895 (14.1%) had toothaches, and 1,906 (6.9%) reported refrained treatment. Among people with decreased income (n = 8,152, 29.6% of overall participants), the proportions of the refrained treatment group were 8.0% (income decreased by 1%-49%), 9.9% (50%-99% decreased), and 9.1% (100% decreased). Among participants with toothache, after adjusting for all variables, compared with participants with no income change, we observed significantly higher prevalence ratios (PRs) for refrained treatment in those who experienced a decreased income owing to COVID-19 (1%-49% decrease: PR = 1.08; 95% confidence interval [CI], 1.005-1.17; 50%-99% decrease: PR = 1.18; 95% CI, 1.06-1.32; 100% decrease: PR = 1.18; 95% CI, 1.04-1.33).

CONCLUSION

Decreased income was associated with refrained dental treatment during the COVID-19 state of emergency in Osaka, Japan. The economic damage related to the COVID-19 pandemic could lead to oral health inequalities.

KNOWLEDGE TRANSFER STATEMENT

Our study found that individuals with decreased income owing to COVID-19 before and after the state of emergency showed significantly higher prevalence ratios for refraining from visiting a dentist despite wanting treatment for toothache. We believe that our study makes a significant contribution because it provides novel, basic data that economic damages related to the COVID-19 pandemic might expand to oral health inequalities.

Gene expression shapes the patterns of parallel evolution of herbicide resistance in the agricultural weed Monochoria vaginalis

The evolution of herbicide resistance in weeds is an example of parallel evolution, through which genes encoding herbicide target proteins are repeatedly represented as evolutionary targets. The number of herbicide target-site genes differs among species, and little is known regarding the effects of duplicate gene copies on the evolution of herbicide resistance. We investigated the evolution of herbicide resistance in Monochoria vaginalis, which carries five copies of sulfonylurea target-site acetolactate synthase (ALS) genes. Suspected resistant populations collected across Japan were investigated for herbicide sensitivity and ALS gene sequences, followed by functional characterization and ALS gene expression analysis. We identified over 60 resistant populations, all of which carried resistance-conferring amino acid substitutions exclusively in MvALS1 or MvALS3. All MvALS4 alleles carried a loss-of-function mutation. Although the enzymatic properties of ALS encoded by these genes were not markedly different, the expression of MvALS1 and MvALS3 was prominently higher among all ALS genes. The higher expression of MvALS1 and MvALS3 is the driving force of the biased representation of genes during the evolution of herbicide resistance in M. vaginalis. Our findings highlight that gene expression is a key factor in creating evolutionary hotspots.

Hospital volume and five-year survival after cancer surgery in 2007-2011 in Osaka, Japan

Background

The relationship between hospital volume (HV) and patient outcome is well-known evidence, and hospital volume is widely used as a quality indicator. In Japan, however, few studies are available on the associations between HV and survival after cancer surgery. This study aimed at examining the association between HV and longitudinal survival after surgeries of major cancer sites.

Methods

This is a retrospective observational study. Using the Osaka Cancer Registry database, we identified patients who were diagnosed as major sites of cancer (esophageal, gastric, colorectal, pancreatic, lung, breast, and uterus cancer) between 2007 and 2011, and undergone surgeries in Osaka. To define the quartiles of HV (high, medium, low, and very low-volume hospitals), we ranked hospitals by annual surgical volume, sorted patients in descending order of HV, and assigned them into four equal-sized groups. The study outcome was five-year survival from the diagnosis. We analyzed the associations between hospital volume and survival among eligible patients aged between 15 and 84 years old, using Cox proportional hazard models. In the models, we adjusted for characteristics of patient and treatment received by the patients.

Results

A sample of 86,867 patients were analyzed. The mortality hazards of patients treated at very low-volume hospitals were 1.4 - 2.1 times higher than that of patients treated at high-volume hospital in all selected cancers. However, absolute differences (percent points) in adjusted survival rates between high- and very low-volume hospitals were varied by cancer site: esophagus (24.2), stomach (14.9), colorectum (11.5), pancreas (9.2), lung (10.8), breast (2.4), and uterus (3.3).

Conclusions

Very low-volume hospitals showed the poorest patient survival after cancer resections. Healthcare quality assessment at lower-volume hospitals and referrals to higher-volume hospitals are potential measures to improve survival of cancer patients.

Key messages

Patients treated at lower-volume hospitals had a higher mortality risk than those treated at higher-volume hospitals. Healthcare quality assessments and effective referrals of high-risk patients are potential interventions to improve patient survival.

Generating an agricultural risk map based on limited ecological information: A case study using Sicyos angulatus

In this study, we propose a method for estimating the risk of agricultural damage caused by an invasive species when species-specific information is lacking. We defined the "risk" as the product of the invasion probability and the area of potentially damaged crop for production. As a case study, we estimated the risk imposed by an invasive weed, Sicyos angulatus, based on simple cellular simulations and governmental data on the area of crop that could potentially be damaged in Miyagi Prefecture, Japan. Simulation results revealed that the current distribution range was sufficiently accurate for practical purposes. Using these results and records of crop areas, we present risk maps for S. angulatus in agricultural fields. Managers will be able to use these maps to rapidly establish a management plan with minimal cost. Our approach will be valuable for establishing a management plan before or during the early stages of invasion.

In vivo time-resolved DOT measurement and image reconstruction of human forearm under exercises

In vivo measurement of time-resolved diffuse optical tomography (TR-DOT) were performed for human forearms under the exercises. The DOT images of oxygenation state were reconstructed, and the activities of the inner muscles were assessed.

Reduction of noise from magnetoencephalography data

A noise reduction method for magnetoencephalography (MEG) data is proposed. The method is a combination of Kalman filtering and factor analysis. A state-space model for a Kalman filter was constructed using the forward problem in MEG measurement. Factor analysis provide estimations of noise covariances required by the Kalman filter to eliminate independent additive sensor noise. The proposed method supports independent component analysis (ICA), which is difficult to use in MEG analysis owing to the sensor noise. Numerical experiments were conducted to investigate the performance of the proposed method. In a single dipole case where the maximum signal-to-noise ratio (SNR) was -10 dB, approximately equivalent to raw MEG data, noise-free signals were successfully estimated from noisy data; a 0.02 s delay of the peak latency and 15-40% of attenuation of the peak amplitude were observed. Moreover, in a multiple dipole case, independent components preprocessed with the proposed method had high correlation, 0.88 at the lowest, with correlation of 0.69 and 0.52 for those preprocessed with conventional bandpass filters. The results show that the noise reduction method reduces sensor noise effectively. High SNR-independent components are obtained by the proposed method. Real MEG data analysis was also demonstrated. The proposed method extracted auditory evoked responses from unaveraged single-trial data.

Coronary risks after high-dose gamma-globulin in children with Kawasaki disease

OBJECTIVES

The goals of the present study were to develop a predictive coronary risk scoring system after intravenous gamma-globulin (IVGG) therapy of any dose for the different preparations currently used in the treatment of children with Kawasaki disease and to determine the predictive value of the system. The previously reported scoring systems were based on treatment with high-dose IVGG therapy at limited doses and were determined using investigative methods.

METHODS

Four hundred and fifty-one patients were randomized into one of three groups and received either i.v. polyethylene glycol-treated human immunoglobulin at a dose of either 200 (n = 147) or 400 mg/kg per day (n = 152) or freeze-dried sulfonated human immunoglobulin at 200 mg/kg per day (n = 152) for 5 consecutive days. We documented 31 cases of coronary abnormalities (CA). Univariate and multivariate logistic regression was performed using 49 clinical variables and the resulting predictive model was validated.

RESULTS

The duration of fever (odds (I day)/odds (- 5 days)= 0.158; 95% confidence interval (CI) 0.0385-0.648), hemoglobin (odds (Q1 = 10.3)/odds (Q3 = 11.6) = 3.97; 95% CI 1.92-8.20), IgG (odds (Q1 = 1,900)/odds (Q3=2,658)=2.72, 95% CI 1.18-6.25) and IgA (odds (Q1 =72)/odds (Q3= 160) = 0.415; 95% CI 0.253-0.680) levels after completion of gamma-globulin infusion were independent predictors. The model is quasi-cross validated and has acceptable sensitivity and selectivity. The estimated risk and observed occurrence of CA coincide.

CONCLUSIONS

Determinants of the risk of CA after IVGG therapy are a longer duration of fever, a lower IgG level, a higher IgA level and a lower hemoglobin level after IVGG infusion. This model is applicable for IVGG doses from 1 to 2 g/kg and for at least two different gamma-globulin preparations.

New partition technique for two-chamber pressure casting unit for titanium

Although titanium has been widely used in prosthetic appliances, such as cast removable partial denture frameworks, high quality castings are still difficult to obtain. This study proposes a new partition technique using a metal foil for improving castability of a two-chamber pressure casting unit. The metal foil was formed beforehand to bring it in contact with the mold crucible wall so that no clearance was left behind it. Using this formed foil, the mold cavity can be completely isolated from the upper chamber and can be maintained in a vacuum even after the rupture of the foil. Accordingly, a large casting force is generated very quickly, and as a result, castability is expected to be significantly improved. This expectation was confirmed by the experiments using wax patterns including thin plate and mesh plate.

Massive accumulation of M and H subunits of neurofilament proteins in spinal motor neurons of neurofilament deficient Japanese quail, Quv

Quiver (Quv) is a non-sense mutation of neurofilament protein L subunit (NF-L) that causes neurofilament deficiency with preserved microtubules in Japanese quail. Anti-NF-M and anti-NF-H mAbs stained cell bodies of motor neurons in Quv embryo spinal cords much more intense than those in control spinal cords. Volume of motor neurons in Quv spinal cords increased to 2.3 times of control motor neurons. Immunoblot of Quv spinal cords revealed a relative increase in non- and hypo-phosphorylated NF-M and NF-H, and a decrease in the total amount of NFs. Quv sciatic nerves showed faintly reacted phosphorylated NF-M and NF-H. These results suggest that deficiency of assembled neurofilament results in decreased axonal transport of NFs and accumulation of NFs in cell bodies of spinal motor neurons.

Surface composition and structure of titanium polished with aqueous slurry of ferric oxide

Cast plates were prepared from commercial titanium. The plates were polished with a slurry of fine ferric oxide powder. The surface composition and structure were investigated by electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS). In the high pressure-polished surface, iron was non-uniformly distributed but oxygen was mostly uniformly distributed, while in a light pressure-polished surface, iron and oxygen were uniformly distributed though at lower and higher concentrations, respectively. EPMA state analysis and XPS suggested that the iron might exist as Fe2+ in the outermost surface, while it might be in a metallic state in the inner surface layer.

Possible segregation caused by centrifugal titanium casting

The possibility of the segregation under solidification process using a centrifugal casting machine was investigated using an electron probe microanalyzer with elemental distribution map, line analysis and quantitative analysis. When a very small quantity of platinum was added to local molten titanium during the casting process, macroscopic segregation was observed under conditions of density difference of 0.1 g/cm3 at the most, confirming that the centrifugal force of the casting machine is extremely strong. When a Ti-6Al-4V alloy was cast, however, no macroscopic segregation was observed. The centrifugal force of the casting machine examined in the present study hardly results in the body-force segregation in this titanium alloy.

Surface contamination of titanium by abrading treatment

This study investigated the contamination of abraded Ti surfaces. Using a polishing machine, specimens were abraded with waterproof SiC grit papers under water cooling. The abraded surfaces were examined using element analysis, X-ray diffraction, and hardness tests. Contaminant deposits with dimensions reaching about 30 microns were observed throughout the surface. In these deposits, Ti was apparently reduced by about 10% and replaced by Si and O. The chemical bond state of the Si was similar to that of SiC or a titanium silicide. The O was solute in Ti, which increased the surface hardness. The contaminant deposits were amorphous or very thin. The contamination of Ti, the extent of which was related to hardness, resulted from a reaction with abrasives.

[Effects of lactitol on fecal bacterial flora in patients with liver cirrhosis and hepatic encephalopathy]

Lactitol, a non-absorbable synthetic disaccharide, was administered at a dose of 36g/day for 3-4 weeks to 8 patients with liver cirrhosis and hepatic encephalopathy in order to investigate its effects on fecal bacterial flora and clinical symptoms of hepatic encephalopathy. Lactitol significantly increased occupation ratio (ratio to total bacterial number) of anaerobic Bifidobacterium (before administration 7.1% --> after 4 weeks 46.0% (p < 0.05) as well as bacterial count of Lactobacillus. On the other hand, bacterial counts of Bacteroides and Clostridium, which are considered to be NH3-producing bacteria, and that of total aerobic bacteria were not markedly changed, but their occupation ratio were decreased after the administration. Further, tendencies toward decreased fecal pH, increased frequency of defecation and soft stools were observed. As for clinical efficacy, a decrease in blood ammonia concentration, improvement in mental state and flapping tremor were also observed.

A multicenter, randomized, controlled trial of intravenous gamma globulin therapy in children with acute Kawasaki disease

We studied the effect of intravenous, polyethyleneglycol-treated, human immunoglobulin, administered at 200 mg/kg per day (group A: n = 147; male 86, female 61; age < 1 year, 50) or 400 mg/kg per day (group B: n = 152; male 87, female 65; age < 1 year, 52) for five consecutive days and compared it with freeze-dried, sulfonated human immunoglobulin [group C: n = 152; male 87, female 65; age < 1 year, 51), administered at 200 mg/kg per day for five consecutive days, on the prevention of coronary artery abnormalities in Kawasaki disease. Echocardiograms were interpreted blindly and independently. Proportions of 87.1%, 95.4%, and 82.3% in groups A, B, and C, respectively, had no coronary artery abnormalities. The confidence limits of difference between the proportions of groups A and C, groups B and C, and groups B and A were -4.4% and 10.4%, 7.8% and 15.9%, and 4.0% and 10.8%, respectively. Duration of fever and serum immunoglobulin G (IgG) levels were correlated with the prevalence of coronary artery abnormalities. We concluded that intravenous, polyethyleneglycol-treated, human immunoglobulin and freeze-dried, sulfonated human immunoglobulin had clinically equivalent effects on coronary artery abnormalities, and that five daily doses of 400 mg/kg of intravenous, polyethyleneglycol-treated, human immunoglobulin is more effective than that of 200 mg/kg gamma globulin.

Skin holes of titanium casting

The present study describes refractories which contribute to formation of skin holes of Ti casting. Plates consisting of quartz (Qu) and cristobalite (Cr) powders and Qu- and Cr-MgO mixtures were fired at high temperatures and used as phosphate-free molds. The cross-section of the castings was investigated using an optical microscope and an electron probe microanalyzer. Whereas the castings into the Qu molds were almost complete, those into the Cr molds were incomplete. The surface reaction zone of the Qu molds formed a typical layered structure with fewer skin holes. That of the latter extended deeply into the interior with a net-shaped Ti-Si phase, cracks, and holes. Addition of MgO to Cr effectively improved the castability and changed the reaction zone to the typical layered structure. However, slender holes occurred along the mold wall. The overall area around the holes was contaminated by Si and Mg. Probably, this resulted from a reaction of forsterite with Ti. The reactivity difference between Qu and Cr was not related to the fired strength of mold.

Successful aggressive treatment against multiple intra-abdominal metastases from renal cell carcinoma 18 years after nephrectomy

The management of late metastases from renal cell carcinoma is often difficult because of multiple organ involvement. We report a case of multiple metastases from renal cell carcinoma in the duodenum, pancreas, intestine, falciform ligament and liver, 18 years after nephrectomy. The patient underwent a total pancreatectomy following a gastroduodenal arterial embolization to control duodenal bleeding, a resection of the ileum and falciform ligament at a second laparotomy and repeated hepatic arterial embolizations to control the growth of liver metastases. Aggressive treatment should be undertaken in cases of late recurrence of renal cell carcinoma after nephrectomy because of the possibly slow-growing biological character of the tumor.

Involvement of calmodulin- and protein kinase C-related mechanism in an induction process of peroxisomal fatty acid oxidation-related enzymes by hypolipidemic peroxisome proliferators

Trifluoperazine, a calmodulin antagonist, suppressed the clofibric acid-evoked induction of the peroxisomal cyanide-insensitive fatty acyl-CoA oxidizing system and carnitine acetyltransferase in rat liver and also in cultured rat hepatocytes. H-7, a potent inhibitor of protein kinase C, also suppressed the induction of these enzymes by clofibric acid, bezafibrate, Wyl4,643 or mono(2-ethylhexyl)phthalate in cultured rat hepatocytes. This suppressive effect was also confirmed by the protein composition of hepatocytes treated with clofibric acid and these antagonists, where the increase in the amount of peroxisomal bifunctional enzyme by peroxisome proliferator was markedly suppressed by above two antagonists. Profile of the time-dependent changes in the activities of the two enzymes after clofibric acid treatment showed that there might be two phases in the induction process. The initial phase (0-3 days after the treatment) showed a relative low inducing rate and subsequent phase (3-5 days after the treatment) showed an abrupt induction. The suppressive effect of the above two antagonists was significant in the later phase. In a time course study of the induction process of peroxisomal catalase, bifunctional enzyme or 69 kDa integral membrane protein using immunochemical detection, the induction of the membrane protein by clofibric acid was delayed compared with that of the bifunctional enzyme, where the induction was inhibited almost completely by nicardipine. These experimental results suggest that calmodulin- and protein kinase C-dependent processes play an important role in the process of marked induction of peroxisomal enzymes and membrane protein by drugs in rat liver.

[Effect of antiplatelet and anticoagulant therapy on secondary prevention and long-term prognosis after acute myocardial infarction in aged patients]

The long-term efficacy and side effects of antiplatelet and anticoagulant therapy for secondary prevention after the first acute myocardial infarction (AMI) were retrospectively assessed in 133 patients over 60 years of age during a mean follow-up period of 36.6 months. Seventy five patients received antiplatelet and anticoagulant therapy (group 1) and 58 patients did not (group 2). In group 1 patients, 54, 12 and 9 patients received ticlopidine, aspirin and warfarin, respectively. Mean age, sex ratio, site of AMI, max CPK value and left ventricular ejection fraction in the convalescent phase did not differ between the two groups. There were no differences between the two groups in terms of the number and kind of combination drugs such as nitrate, beta-blocker and Ca antagonist. During the follow-up period 40 patients died; 18 patients (45%) suffered cardiac death and 22 patients (55%) experienced non-cardiac death. Nineteen patients had recurrent MI and 37 patients had cardiac events which were defined in total as cardiac death, recurrent MI and unstable angina pectoris. The total mortality rate and rate of recurrent MI based on the life time table method were significantly lower in group 1 than in group 2 by the generalized Wilcoxon test. The cumulative total mortality rate in the fifth year was 24.2% in group 1 and 49% in group 2. The cumulative rate for recurrent MI in the fifth year was 7.4% in group 1 and 27.5% in group 2 (p less than 0.05). However, the rate of cardiac events did not differ between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Molten titanium flow in a mesh cavity by the flow visualization technique

The tracer element molten (TEM) method, which provides titanium flow visualization in a mold cavity, was applied to investigate the flow in a mesh pattern. When a pressure casting machine was used, most of the mesh rods were composed of many solidification layers, which implied that the flow was laminar and almost steady. When a centrifugal casting machine was used, the flow was almost irregular and a stack of solidification layers was observed in only a few segments. These results indicate that the flow was turbulent. In a complicated cavity, such as a mesh pattern, pressure rather than centrifugal force acts as an effective casting force. Therefore, in such a cavity, favorable castability can be achieved with high pressure and laminar flow.

Cardiac sequelae of Kawasaki disease in Japan: statistical analysis

The proportions of Kawasaki disease patients with cardiac sequelae in Japan were analyzed using nationwide survey data from the 6 1/2-year period July 1982 through December 1988. Of 46,864 cases of Kawasaki disease reported in the surveys, 7637 or 16.3% had cardiac sequelae such as dilation or stenosis of coronary arteries, myocardial infarction, and valvar lesions 1 month or more after onset. The prevalence of cardiac sequelae was particularly high in males, infants younger than 1 year, and children older than 5 years of age. In sequential observation, there was no correlation between the prevalence of cardiac sequelae and periods of high or low incidence of the disease. The prevalence of cardiac sequelae overall declined steadily over the observation period, perhaps as a consequence of increasing use of intravenous gamma globulin. However, children older than the age of 5 years manifested increasing prevalence of cardiac sequelae over the observation period, probably as a result of lower rates of intravenous gamma globulin administration.

Co-suppression by nicardipine, a calcium antagonist, of induction of microsomal lauric acid hydroxylation with peroxisome proliferation in clofibrate-treated rat liver

The in vivo effect of nicardipine, a well-known calcium antagonist, on microsomal omega-oxidation of laurate in clofibrate-treated rat liver was studied. The 15.3-fold induction of the activity by 2 weeks administration of 0.25% clofibrate in the diet was markedly suppressed to about 6-fold by co-administration of nicardipine at 100 mg/kg body weight. Similarly, the induction of peroxisomal beta-oxidation and carnitine acetyltransferase activities were also suppressed by this simultaneous administration by more than 50%. Although clofibrate also induced the activity of reduced nicotineamide adenine dinucleotide phosphate (NADPH)-cytochrome c reductase and increased the hepatic content of cytochrome P-450, no suppressive effect of nicardipine was observed. Contrarily, nicardipine induced the reductase activity and increased the hepatic content of cytochromes P-450 and b5. These results provide the first demonstration of a calcium antagonist, e.g. nicardipine acting as inhibitor of the induction of microsomal omega-oxidation, in association with the inhibition of peroxisome proliferation in animals. The suppression of drug-induced peroxisome proliferation and microsomal omega-oxidation by the calcium antagonist may help in elucidating the causal relationship of the induction mechanisms between peroxisomal and microsomal enzymes.

[Determination of titanium flow by the tracer element molten method in the dental precision casting. 1. The principle of flow visualization and application to simple castings]

The tracer element molten (TEM) method has been developed for flow visualization of molten Titanium in dental precision casting. The principle of this technique is as follows. When Titanium is cast, the tracer element wire inserted previously into the selective point of the sprue is molten little by little and distributed according to the molten Titanium flow in the mold cavity. After solidification, to observe the flow pattern, the tracer element needs to be analyzed on a section of the casting by EPMA equipped with the stage scan mapping system. This technique using Ag, Au, Pd or Pt as a tracer has been applied to some simple castings in shape and has been confirmed to be a very powerful technique for Titanium flow visualization in dental castings.

[Reactions at the nonprecious metal-ceramic interface during porcelain firing. (3) A commercial alloy forming much Cr oxide during firing]

To examine the interface reaction between porcelain and a commercial Ni-Cr dental alloy (containing higher Cr and Mo) during porcelain firing, electron probe microanalyzer (EPMA) and X-ray diffraction have been used to characterize the interface which has emerged by means of selective dissolution of the alloy caused by a bromine-methanol solution. Much Cr oxide was formed at the early stage of firing, and remained in the reaction layer even if the holding time at 960 degrees C was up to 8 minutes. As a result, many Cr atoms diffused into the porcelain layer, most of which was found to form oxides through X-ray diffraction. Moreover, the porcelain layer nearest to the oxide layer was deduced to be modified seriously.

[Grinding of titanium. 2. Commercial vitrified wheels made of alumina abrasives]

Cast titanium was ground with commercial vitrified wheels made of alumina abrasives, and their grinding performance was investigated. For cutting, the appropriate circumferential speed of the alumina wheels was about 700 m/min. A speed lower or higher than this yielded unfavorable grinding results, which were attributed to wheel loading or chemical attrition of the abrasive, respectively. The hard wheel made of the A abrasive was suitable for grinding of titanium, and moreover, the wheel of the WA abrasive was more suitable than that made of the A abrasive. Generally, the cutting rate of the alumina wheels was inferior to that of the silicon carbide ones investigated previously. Depression of the wheel against the work yielded unfavorable grinding results; the manner in which the wheel was moved over the work during grinding was very important, compared with the silicon carbide wheels. Although the wheel was moved over the work, the high circumferential speed of the wheel resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn. The grinding burn layer mainly consisted of a few microns-thick titanium oxide.

[Grinding of titanium. 1. Commercial and experimental wheels made of silicon carbide abrasives]

Cast titanium was ground with commercial and experimental wheels made of silicon carbide abrasives, and their grinding performance was investigated. With the vitrified wheels made of the GC abrasive, at a higher the wheel circumferential speed and heavier the grinding pressure, the cutting rate was greater, accompanied by violent wear of the wheel. Being independent of the wheel speed, the grinding ratio reached about 1 under pressure heavier than 100 gf. The MgO-MgCl2-bonded wheels of the C abrasive exhibited a similar tendency. The manner in which the wheel was moved over the work during grinding proved to be very important, compared with the Ni-Cr alloy as reported previously. Only depression of the wheel against the work resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn, due to oxidation of titanium. Even when the wheel was moved over the work, chip-formation process of the cutting edge was far from ideal, and the work surface was contaminated due to reaction of titanium with the abrasive. At a higher wheel circumferential speed, more chips were loaded or built-up in the wheel and strongly rubbed the work surface, resulting in violent wear of the wheel; loading and dislodging of such chips were repeated.

Layered structure of cast titanium surface

The present study concerns the surface layered structure of the cast Ti. A commercial Ti was cast into a mold which was made of a phosphate-bonded Al2O3/SiO2 investment. Elemental analyses of the interfacial zone of the casting were made under an electron probe micro-analyzer. The interfacial zone was composed of four layers: the outermost reaction or casting burn layer, the second layer of an O-and Al-stabilized alpha case, the third layer in which Si, P, O, and C were inhomogeneously concentrated, and the fourth layer which consisted of acicular or plate-like crystals. It was observed that the larger the cast volume and the higher the mold temperature, the thicker became each layer and the coarser became the acicular grains. Probably, the layered structure was formed through decomposition of reducible species in the burnout investment and diffusion of the resulting elements into the casting.

[Study on grinding of base metal alloys. 4. Constant pressure grinding of a Ni-Cr alloy with vitrified wheels]

The grinding techniques and the constituent element of vitrified wheels suitable for a 13% Cr-Ni dental casting alloy were determined. The lever-type grinding test machine used in the previous study was modified so that a work might be ground under a constant pressure as it moved reciprocally within a short stroke along the tangential direction of a rotating wheel. The grinding performance of two marketed wheels and eleven experimental wheels with different constituent elements was tested. Abrasive grains on the working surface of alumina wheel wore extremely due to abrasive attrition. Carborundum wheels proved to be more suitable for grinding of the comparatively soft Ni-Cr alloy. Not only depressing a wheel against a work but also moving the wheel over it with heavier pressure should be desired for the maximal grinding efficiency. The experimental carborundum wheels exhibited much the same performance as the marketed carborundum wheel under a less grinding pressure that 100 gf. Only the wheel of grain size #150 bonded with 19% binder wore obviously under the pressure of 150 or 200 gf and provided about two times the performance of the marketed wheel.

[Reactions at the nonprecious metal-ceramic interface during porcelain firing (2). A commercial alloy containing higher Cr and Si]

To clarify the interface reaction between porcelain and a commercial Ni-Cr dental alloy (containing higher Cr and Si) during porcelain firing, electron probe microanalyzer (EPMA), X-ray diffraction and X-ray fluorescence analysis have been used to characterize the interface which has emerged by means of selective dissolution of the alloy caused by a bromine-methanol solution. At the early stage of firing, tin oxides (SnO2), contained in the porcelain powder, were reduced to Sn metal and the resultant reduction layer was about 10 microns in thickness from the interface. Although in the beginning of firing some Cr oxides were formed at the interface, with increasing retention time (within a few minutes) at 960 degrees C, extremely low oxygen partial pressure caused reduction of even such products.

[Study on grinding of base metal alloys. 5. Constant pressure grinding of a Ni-Cr alloy with electro-deposited wheels]

The grinding techniques and electro-deposited wheels suitable for a 13% Cr-Ni dental casting alloy were determined. The lever-type grinding test machine modified in the previous study was used to investigate the grinding performance of experimental wheels of CBN- and diamond-particles. Depression of the diamond wheel against the work yielded unfavorable grinding results. Not only depression of the wheel against it but also moving the wheel over it with a heavier pressure is desired for higher grinding efficiency and its durability. Probably, the undurability of this wheel is associated with abrasive attrition due to oxidation or some chemical reaction with the work. The CBN wheel had not been suitable for the Co-Cr alloy tested in the third paper, but it exhibited very excellent performance for grinding of the Ni-Cr alloy, even without being moved over the work. Although being high in cost, the CBN wheel may pay for the very high performance and its durability.

Clinical application of Hobel's high-risk pregnancy scoring system

Hobel's high-risk pregnancy screening scoring system was applied to 1,000 deliveries prospectively to test the validity of the screening system. Our results showed that the incidence of high-risk neonates increased significantly as the risk scores during the prenatal and intrapartum periods increased. In this series, 57.7% of the patients belonged to the low-low risk group and 9.8% was classified as the high-high risk group. The incidence of high-risk neonates in the low-low risk group was 13.5% whereas it was 32.0% in the high-high risk group. Further, maternal hypocapnia during delivery was found to be closely related to the incidence of neonatal hyperbilirubinemia in this series and proper management of maternal ventilations during delivery could reduce the incidence of neonatal hyperbilirubinemia.

Intraarterial digital subtraction angiography with carbon dioxide: superior detectability of arteriovenous shunting

Intraarterial digital subtraction angiography (IADSA) with carbon dioxide (CO2) was performed on 41 patients with liver or renal diseases. CO2 produced no hypersensitivity reactions, and the pain or feeling of warmth was relatively mild compared with iodinated contrast media. Although the image quality of the arterial or capillary phase was inferior to that with iodinated contrast media, the detectability of arteriovenous shunting was excellent. IADSA with CO2 may become an effective method for detecting arteriovenous shunting which cannot be demonstrated with conventional angiography or DSA with iodinated contrast medium.

Activation of platelets in cancer, especially with reference to genesis of disseminated intravascular coagulation

Seventy-five cancer patients were evaluated on a scale of coagulation abnormalities related to DIC, one point given for each of the following criteria fulfilled and the score (0 to 4) being used. 1. Platelet count less than 150 x 10(3)/mu 1. 2. PT prolonged more than 1 sec over control or APTT prolonged more than 10 sec over control. 3. Fibrinogen less than 250 mg/dl (mean fibrinogen value of the cancer patients minus 1SD). 4. FDP greater than or equal to 20 micrograms/ml. The patients were distributed with 27% for score 0, 38% for 1, 20% for 2, 7% for 3 and 8% for 4. Platelet mode volume in score 4 was smaller than that of the other groups. Platelet aggregation by epinephrine was decreased in score 3 and 4 (P less than 0.01), while it was increased in score 0 (P less than 0.05). ADP-induced aggregation was increased in score 0 and 1 (P less than 0.01 - 0.05). The mean value of beta-thromboglobulin in cancer patients (44 +/- 24 ng/ml) was significantly higher than that of control (22 +/- 13 ng/ml) (P less than 0.01). These results suggest the existence of hyperfunction of platelets in cancer patients and possibility of a triggering mechanism of such activated platelets in the genesis of DIC in cancer.

[Studies on the dynamic durability of dental restorative materials. Part 4. Materials evaluation of initial and fatigue specimen for composite resins by acoustic emission method]

Present study is directed towards development for a method of materials evaluation of the static and dynamic properties for dental restorative materials and nondestructive inspection of the dental restorations in oral cavity by acoustic emission (AE) method. AE characteristics and deformation-fracture behavior of hour commercial composite resins under three points bending test are examined in order to evaluate initial and fatigue specimen for conventional and microfilled composite resins. Experimental results obtained are as follows: (1) Deformation-fracture behavior of conventional and microfilled composite resins exhibits different mode, corresponding to relatively brittle and ductile fracture behavior, respectively. Therefore, the primary sources of AE for conventional and microfilled composite resins under bending test are related mainly to the nucleation and propagation of cracks and plastic deformation, respectively. (2) In conventional composite resins under bending test, the burst type AE signal of higher amplitude and shorter decay time and more many AE total counts tend to be observed. In microfilled composite resins under bending test, the burst type AE signal of lower amplitude and longer decay time and more a few total counts tend to be observed. (3) Composite resins, particularly conventional composite resins under unload and repeated bending load are indicative of different AE characteristics. Accordingly, application of AE method for composite resins offers a method to evaluate the static and dynamic strength of composite resins. (4) In conventional composite resins under bending test, as characteristic AE are observed in a few stress regions before fracture, it may be possible to monitor nondestructively the restorations in oral cavity by using AE method.

[Studies on the dynamic durability of dental restorative materials. (Part 2) Properties for the repeated impact compressive load ot composite resins (author's transl)]

Based on the fracture energy form the compression test of composite resins under the repeated impact loads in compression after stored for a period in water at 37 degrees C, the dynamic durability of commercially used composite resins was evaluated. The results obtained were summarized as follows. (1) The fracture energy of composite resins under the repeated impact compressive loads after stored in water at 37 degrees C is clearly lower than the initial fracture energy. Particularly the decrement of the initial fracture energy for Concise, Epolite 100 and Superlux after stored for 30 days in water at 37 degrees C is influenced considerably both by the physicochemical degradation caused by water and the mechanical deterioration caused by the repeated impact compressive loads, but Clearfil is superior to the mechanical deterioration. (2) In each composite resins, there is a close correlation between fracture energy and compressive strain. In composite resins without Superlux, also a correlation is in fracture energy and compressive strength. (3) In clearfil, concise and Epolite 100, the morphology of fracture in compression test of composite resins which are subjected to and are subjected to the repeated impact loads in compression is classified in a mode of shear fracture, but in Superlux, a mode of crack fracture.

Use of rabbit antiboty IgG bound onto plain and aminoalkylsilyl glass surface for the enzyme-linked sandwich immunoassay

Rabbit antibody IgG was bound onto aminoalkylsilyl or plain glass rods by simple adsorption. For comparison, rabbit antibody IgG was also bound onto glutaraldehyde-activated aminoalkylsilyl glass rods. These antibody-glass rods were tested by the sandwich procedure using Fab' fragments of rabbit antibody conjugated with beta-D-galactosidase from Escherichia coli. The glutaraldehyde-activated aminoalkylsilyl glass showed the largest capacity to bind antigen and the plain glass showed the smallest. However, the antibody-glass rods prepared by simple adsorption were as useful for the sandwich immunoassay of macromolecular antigens as those prepared with glutaraldehyde. With all the antibody-glass rods prepared, 0.1 to 10 fmol of ornithine delta-aminotransferase from rat liver and 2,4-dinitrophenyl human IgG were measurable. More than 10 fmol of the antigens may be measurable with larger amounts of the antibody-beta-D-galactosidase complexes, although the non-specific binding of the complexes to the solid phase increases to limit the sensitivity of the immunoassay.