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We report a case of a staghorn stone containing ammonium acid urate that was effectively treated with drug therapy alone. A 46-year-old man had recurring urinary tract stones. He had no previous episode of urinary tract stones that required hospitalization and operation. He received only drug therapy for hyperuricemia in another hospital. Ultrasonography and computed tomography revealed a left staghorn stone measuring 37×34 mm. The kidney-ureter-bladder radiograph did not show any stones. His urine was acidic, and we estimated that the left staghorn stone consisted of urate. Oral administration of sodium hydrogen carbonate was initiated to alkalize the urine, and treatment with transurethral lithotripsy (TUL) was scheduled. Before the TUL, analysis of an excreted stone sample revealed that it consisted of ammonium acid urate. The staghorn stone was completely removed in 10 months after the first medical examination. At present, the patient is free of urinary tract stones.

Indomethacin (IM) oral spray is a hospital preparation that is used to reduce pain from oral mucositis induced by radiotherapy and chemotherapy. IM oral spray consists of IM (0.25%) dissolved in KH 2 PO 4 -NaOH buffer (Formulation A) or Formulation A containing xylitol (Xyl) and glycerin (Gly) (Formulation B). To clarify the stability of IM oral spray in two different formulation conditions, we evaluated the residual rates of IM in these formulations to determine the optimal storage temperature and shelf-life. IM oral spray was stored at freezer temperature (-20°C), refrigerator temperature (4°C) and room temperature (25°C) for up to 16 weeks after preparation. The residual rate of IM was determined by using HPLC. The residual rates of IM in Formulation A and Formulation B after storage for 16 weeks at freezer temperature were ≥95%. When stored at refrigerator temperature, the residual rate of IM in Formulation A was 96.1% after 12 weeks, and the residual rates of IM in Formulation B were 95.8% after 2 weeks, 90.1% after 4 weeks and 72.7% after 12 weeks. These results suggested that Formulation A is stable for at least 12 weeks when stored at 4°C. However, degradation of IM seemed to be accelerated in the formulation containing Xyl and Gly, suggesting that the expiration date should be shortened to 2 weeks at 4°C. In addition, both formulations were stable for at least 16 weeks in a freezer, indicating that long-term preservation is possible.

In order to characterize the adhesion and deformation behavior between chitosan-modified liposomes and the mucin layer of the small intestine, mucin was coated on hydrophobic surface-modified carbon nanotube (CNT) probe of an atomic force microscope. The interaction between this mucin layer and the liposomes with or without chitosan modification in phosphoric acid buffer solution was determined by atomic force microscopy. The pH of the buffer solution was controlled at 2.8 and 7.0. The chitosan modification increased the attractive force between the liposomes and mucin layer during the separation process under both pH conditions. This result corresponded with that from a previous study about the liposome adhesion behavior on the surface of the small intestine of rats. By using the mucin-coated CNT probe, the long range and different types of attractive forces between the chitosan-modified liposomes and mucin layer was observed. Furthermore, the small-scaled deformation behavior change on the liposomal surfaces due to chitosan modification was also observed by the CNT probe. The detail deformation and adhesion behavior of the liposomes with or without chitosan modification was detected.

Phosphorus, as a phosphate is a component of bone, cellular membrane, and also high-energy phosphate compounds, and nucleic acids. Also phosphate acts as a buffer to maintain the pH and is concerned with functional regulation of several proteins and intracellular signaling through the phosphorylation/dephosphorylation. Thus phosphorus plays a variety of important roles intracellular and extracellular component. A disorder of phosphate homeostasis results bone disorder and general metabolic dysfunction of all body tissues and organs.

We developed and evaluated methods of quantifying cyanide (cyanide ion and cyanogen chloride) and bromic acid in mineral waters (MW). After performance evaluation, recovery studies were performed on 110 kinds of MW products to examine the applicability of the methods. The approximate proportion of the MW samples, in which the recovery rate of these anionic compounds was within 90 to 110%, was 95% in the cyanide ion and bromic acid analysis and 45% in the cyanogen chloride analysis. We observed low rates of recovery of cyanogen chloride from some MW products with pH values around neutral. To increase the recovery rate, we propose adding phosphoric acid buffer to adjust the pH of these MW samples. The retention times for bromic acid in some MW products differed from that in standard solution. We concluded that carbonic acid influences the retention times. It may be necessary to to exclude carbon dioxide from the MW samples by degassing to synchronize the retention times of bromic acid in the MW samples and the standard solution.

The dissolution test is a core performance test in pharmaceutical development and quality control of solid drug products. The conventional HPLC dissolution method (batch-sampling method) involves many steps including the filtration, collection and replenishment of sample solutions. We previously reported a dissolution test that involved microdialysis methods (microdialysis-HPLC method) and allowed many steps to be omitted. However, the recovery rate of theophylline by the microdialysis-HPLC method was lower, and the decrease in the flow rate through the dialysis probe caused variation between each tablet. In this study, we have attempted to improve the dissolution test by using a precise micro-controlled roller pump and microfiltering probe (microfiltering-HPLC method). Sustained release preparations of Theodur (100 mg) were used, and the test solutions used were water, buffer at pH 1.2 and pH 6.8, and pH 6.8-buffer containing 0.1-1% polysorbate 80 or sodium lauryl sulfate. In all test solutions, the microfiltering-HPLC method was able to accomplish continuous sampling of sample solutions, and the recovery rate of theophylline was over 90%. The dissolution behavior by the microfiltering-HPLC method tends to reflect the pharmaceutical design in comparison with the batch-sampling method, and the standard deviations by the microfiltering-HPLC are lower than with the batch-sampling method. In addition, the microfiltering-HPLC method allows many steps to be omitted, such as the filtration, collection and replenishment of sample solutions. These findings provide significant information that can be used in the pharmaceutical development and quality assessment of solid drug products.

We report a case of suspected pseudo-elevation of serum creatinine in a patient with rheumatoid arthritis, whose blood sample was obtained from his right cubital vein immediately after the intra-articular injection of 0.67 mg of a pharmaceutical preparation of dexamethasone (Decadron) containing creatinine as a buffer into his right wrist joint to alleviate arthralgia. The 61-year-old male patient, who had been treated for rheumatoid arthritis, was referred to our outpatient clinic by his family doctor because of sudden elevation of his serum creatinine, which hitherto had been normal. Acute kidney injury (AKI) was suspected, but his medical history, physical examinations, and laboratory findings did not support the diagnosis of AKI. The preserved serum sample obtained when the elevation of his serum creatinine was reported was examined and revealed that the serum concentration of cystatin C was normal, but the serum concentration of creatinine measured with high-performance liquid chromatography method was elevated to a degree consistent with the serum creatinine concentration measured with enzymatic method. Accordingly, we predicted the possibility that creatinine contained in Decadron as a buffer was included in the measurement of his intrinsic serum creatinine. To test this hypothesis, the creatinine concentration of serum samples from another patient with known amounts of added Decadron were measured, and the additive effect of the extrinsic creatinine in the measurement of serum creatinine concentration was confirmed. These findings clearly suggest that we should consider the influence of extrinsic creatinine as an inactive ingredient in the measurement of serum creatinine.

Simultaneous and fractional determination of iron(II) and iron(III) was accomplished with o-hydroxyhydroquinonephthalein (QP) in the presence of poly (N-vinyl pyrrolidone). In the determination of total iron (iron(II)+iron(III)), Beer's law was obeyed in the range of 0.02-0.67 μg·ml(-1), with an effective molar absorptivity (at 570 nm) and a relative standard deviation of 1.30×10(5)·l·mol(-1)·cm(-1) and 0.77% (n = 8), respectively. This method was about 10-15 times and more than the methods using 1,10-phenanthroline and 2,2'-bipyridine. In addition, the iron-QP complex was characterized using spectrophotometry and the electron spin resonance. This method was successfully applied to assays of total iron and iron(III) in pharmaceutical preparations.

In this study, 162 students in the 6 year Pharmacy Program at the School of Pharmacy, Iwate Medical University were asked to prepare liposomal preparations using chicken egg yolk and to evaluate their properties with the aim of developing novel liposomes. High-purity lecithins are generally used for preparing liposomes but they are expensive. On the other hand, egg yolk has various components, including lecithin and cholesterol, which are important components for the formation of liposomes, so it was hypothesized that liposomes prepared from egg yolk may participate in the formation of cell membrane in chicks. Both liposomes from egg yolk (YL) and from lecithin (LL) exhibited Malthesian crosses using a polarizing microscope and multilamellar vesicles were observed, confirming that liposomal preparations from egg yolk were useful. The particle size of YL was about 100 nm with one peak. Furthermore, the YL are believed to be viable under different conditions because the particle size did not change when they were prepared in buffers having different pH values. The results of these experiments indicate that liposomal preparations from egg yolk can serve as natural materials, although some obstacles remain. This is a unique approach for carrying out practical training in our 6 year pharmaceutical science program.

We evaluated the stability of temozolomide, an alkylating agent, in solutions after opening the capsule. First, we established an analytical method for determination of temozolomide concentration by HPLC. The calibration curve for temozolomide was linear between 0.5-20 microg/ml (r=0.999). We then evaluated the stability of temozolomide in each buffer solution (pH 2-9) for 30 min. Temozolomide was decomposed pH-dependently between pH 7 and 9, and completely decomposed at pH 9. Temozolomide in several drinking water samples and beverages was decomposed according to their pH values. We also examined the time-dependent degradation of temozolomide in different pH solutions. Temozolomide started to decompose at 5 min in alkaline and neutral solutions, whereas 90% of temozolomide remained intact in acidic solution at 60 min. These results indicate that the stability of temozolomide after opening the capsule is affected by pH of solvents, and temozolomide is almost stable in acidic solutions.

Several substances other than antigens are included in vaccines. These are classified as follows: stabilizers, preservatives, buffer, adjuvants, antibiotics etc. Some of these substances, for example gelatin and thimerosal, have been removed from vaccines because of their undesirable side effects. However, stability and sterility are very important conditions for vaccines. Therefore, removal of excipients from vaccines should be investigated very carefully. Impurities derived from culture substrates for bacteria and viruses should be reduced as much as possible. Japanese vaccines are highly purified. For example, influenza vaccines contain only a few ng/dose of OVA which are significantly lower than the WHO standards (5 microg/dose).

Purpose: The Preparation of rest seat and guiding plane is an essential part of the prosthetic restoration for partial denture treatments. Although these preparations are confined within the outer enamel surface, cut surfaces are left exposed after completion, which involve potential risks of caries. This study observed the morphological change of the cut surface of the enamel in vivo., Methods: The prominent areas of bucco-lingual surfaces of the volunteers' third molars to be extracted, were cut with a dental turbin. The prepared tooth was then left for while (3, 6 months) in the oral cavity, and subsequently extracted. Either cut and non-cut surface were observed by SEM,TEM, HRTEM. In addition, salivary buffer test and cariostat test were introduced., Results: In most subjects, salivary buffer test showed "middlespillage" with "high buffer", and cariostat test showed "attention area". The observation of SEM showed that the enamel prism was not broken although cut and non-cut surface of the enamel were covered with bacterial flora. The observation of TEM and HRTEM revealed that the apatite crystal had dissolution and broken in both cut and non-cut area., Conclusion: Comparative study of cut and non-cut surface of the enamel showed that the apatite crystal had dissolution and broken in two stages.

Background: Selection of low-allergen trees is under consideration for the reduction of Sugi (Cryptomeria japonica) pollinosis. The extraction method of Cry j 2 was established and then the variation of Cry j 2 concentrations in pollen among Sugi trees was investigated., Methods: The extraction efficiency of Cry j 2 was compared among buffers with different pH, ionic species and NaCl concentration. The Cry j 2 concentration in the pollen of 140 trees was measured using the most efficient buffer., Results: NaHCO3 (0.125 M) + 0.5 M NaCl buffer showed the highest Cry j 2 extraction efficiency. The mean and standard deviation of Cry j 2 concentration among 140 trees was 404 +/- 189 microg/g pollen, which was equivalent to that of Cry j 1 (435 +/- 169 microg)., Conclusion: We revealed that the variation of Cry j 2 concentrations was as large as that of Cry j 1 in the pollen among trees using the newly developed extraction method.

A total of 244 milk samples collected from supermarkets in Tokyo were examined for contamination with Coxiella burnetii. C. burnetii DNA was detected in 131 (53.7%) of the samples by nested PCR. PCR-positive samples were injected into immunosuppressed A/J strain mice. Of the 22 PCR-positive milk samples tested, none resulted in isolation of C. burnetii from the mice. Heat-treatment was sufficient to inactivate C. burnetii in commercial milk. In addition, a PCR detection method for C. burnetii in chicken egg was developed. Egg yolk was added to an equal volume of 1 mol/L of NaCl phosphate buffer and homogenized for removal of protein and lipid. After centrifugal separation, the supernatant was removed, and template DNA in the precipitate was extracted using SDS, proteinase K and NaI. Using such prepared samples, 3.2 x 10(1) C. burnetii particles in 1 g of egg yolk could be detected by nested PCR. All of 200 chicken egg samples collected from supermarkets in Tokyo were negative for C. burnetii by the nested PCR method.

Sodium benzoate is a kind of preservatives in cosmetics and is nominated as the restricted ingredients in cosmetics in Japanese Pharmaceutical Affairs Act. So the analytical method for sodium benzoate was investigated by HPLC. After adding 5 ml of tetrahydrofuran to 0.05 g of the lotions or creams with 0.1 or 1.0% sodium benzoate and dissolving them, that mixture was made up to 50 ml with methanol. If necessary, the mixture was filtrated with a membrane filter (0.45 microm). The testing solution of 20 micro1 was analyzed by HPLC using the ODS column (CAPCELL PAK C18 column, 4.6 x 250 mm), the mixture of 50 mmol/l phosphate buffer (pH5.5) and acetonitrile (7:3) and the detection wavelength of 227 nm. The working curve from 1.0 to 12.0 microg/ml showed a linear line between the concentrations of sodium benzoate and the peak area. There was no interference of peak of sodium benzoate from the lotion and cream.

We studied the impact of perfusate buffer composition on the relative degree of protection afforded by Na+/H+ exchanger (NHE) inhibition during ischemia as opposed to during reperfusion. Isolated rat hearts were perfused with bicarbonate- or HEPES-buffered medium. There was infusion of HOE 694 immediately before ischemia, during initial reperfusion, or during both of these periods. With bicarbonate-buffered medium, HOE 694 improved the post-ischemic recovery of left ventricular developed pressure (LVDP) when given before ischemia and before ischemia plus during reperfusion. In the presence of HEPES-buffered medium, however, HOE 694 significantly improved recovery of LVDP in all protocols. HOE 694 also provided an almost complete recovery of LVDP (88 +/- 9% vs 30 +/- 7% in controls) when given before ischemia plus during reperfusion. In conclusion, our results suggest that the influence of NHE activity during reperfusion on the extent of functional recovery is modulated significantly by perfusate buffer composition.

Potassium ion (K+) is the only cation whose concentration in intracellular solution is more abundant than in extracellular fluid. In higher animals, each of the cells, which is bathed in the extracellular fluid containing approximately 5 mM K+, has approximately 140 mM K+ in its cytoplasm. Physiological experiments have reported that the glial cells such as brain astrocytes and retinal Müller cells highly express K+ conductance on their membrane. The K+ conductance is thought to be responsible for transport of K+ from the extracellular regions of high K+, which is elicited by the excitation of neurons, to those of low K+. This so-called glial K(+)-buffering action is essential for maintenance of neuronal activity. Types and distribution of the K+ channels involved in the buffering action, however, have remained unknown for a long time. Recently, we have identified that an inwardly rectifying K+ channel, Kir4.1, is dominated in glial cells and plays a central role in the K(+)-buffering action. We also found that Kir4.1 is enriched on the processes of astrocytes wrapping synapses and blood vessels. Furthermore, some of the Kir4.1 is assembled with Kir5.1, suggesting that a heteromultimer of Kir4.1 and Kir5.1 plays a distinct role in the glia.

The quantification method of urinary hemoglobin has not been established. We examined whether a reagent (Eiken, Tokyo) used to immunologically assay fecal hemoglobin could be utilized to quantify urinary hemoglobin. The coefficients of variation were 2.2-3.0% in the reproducibility of one-run assays using urine and 4.3-5.7% in that of multiple-run assays using the standard sample of hemoglobin. Urinary hemoglobin was unstable and decreased in a time- and temperature-dependent manner. However, addition of the hemoglobin stabilization buffer (50 mM phosphate buffer, pH 6.4) (Eiken) to urine made urinary hemoglobin stable. Urinary hemoglobin levels did not change significantly when stored at 4 degrees C for 7 days or at -80 degrees C for 30 days. The hemoglobin concentration (mean +/- SD) of urine showing 1+, 2+ and 3+ with a test strip was 385 +/- 165(n = 30), 1070 +/- 499(n = 40) and 4130 +/- 2770 ng/ml (n = 20), respectively. Urinary hemoglobin did not correlate with urinary albumin, transferrin, immunoglobulin G, N-acetyl-beta-D-glucosaminidase nor alpha 1 microglobulin. These results suggest that this immunological method using the hemoglobin stabilization buffer can be utilized for quantification of urinary hemoglobin, which may provide clinically important information.

Anti-microbial effect of the pretreatment with various organic acid buffer solutions against co-existing microorganisms which were isolated from cooling-tower water samples along with Legionella spp. was examined. Among several buffer solutions, a 0.1 M potassium citrate-citric acid buffer solution (hereafter, citrate buffer solution, pH 2.2) hardly affected the recovery of Legionella spp., but effectively inhibited the growth of co-existing microorganisms. To evaluate the buffer action of these buffer solutions, pHs of 9 cooling-tower water samples were evaluated after addition of an equal volume of each buffer solution. When a citrate buffer solution. pH 2.2 was combined to a 200-fold concentrated solution of each cooling-tower water sample, the pH of the combined solution became 2.5 to 2.7 and maintained a stably low pH value than that (pH 3.0 to 7.4) obtained after mixture of a 0.2 M HCl-KCl buffer solution (hereafter, HCl buffer solution, pH 2.2), suggesting strong buffer action of the citrate buffer solution, pH 2.2 in the combined solutions. Furthermore, when cooling-tower water samples were pretreated with a citrate buffer solution, pH 2.2, the recovery of Legionella spp. was successful in 7 out of 9 cooling-tower water samples, suggesting 3 times higher recovery rate than that obtained by addition of a HCl buffer solution, pH 2.2 (3 out of 9 cooling-tower water samples).

The present investigation dealt with the effect of simultaneous administration of flumazenil on the hypnotic activity of propofol using a behavioral model of ddY mice. The mixed solution of propofol and flumazenil was administered intravenously into the mice tail vein and the achievement of hypnosis was defined as the loss of the righting reflex. Flumazenil 0.2 mg.kg-1 significantly decreased the required dose of propofol for hypnosis (8.43 +/- 0.46 mg.kg-1) compared to the control group (10.55 +/- 0.55 mg.kg-1). The mixture with a pH-3.9 acetate buffer solution did not change the hypnotic dose of propofol (10.88 +/- 0.62 mg.kg-1). The results suggest that flumazenil might potentiate the hypnotic activity of propofol in ddY mice.

Increasingly complex techniques of cardiac surgery often require prolonged myocardial ischemia. We previously reported a better myocardial preservation with histidine containing cardioplegia (HBS) in human open heart surgery. To see a safety margin of this cardioplegia for prolonged myocardial preservation, this study was retrospectively done. One hundred twenty-six patients received either intermittent multidose (20-30 minute) cold blood cardioplegia (CBC) plus topical cooling (aotric cross clamp time (ACC) < 120 minutes, n = 63) or HBS (n = 63). HBS group was divided into two groups with either short ACC (< or = 120 minutes, HBS-S, n = 46) or long ACC (> 120 minutes, HBS-L, n = 17). Cardiac index (C.I.) and dopamin/dobutamine requirement were measured 3, 6, and 12 hours post-bypass. Incidence of homologous blood transfusion was also studied. There was two deaths due to LOS in HBS-S group; four patients in HBS group required 5 DC cardioversion, whereas six patients required a total of 12 DC cardioversion in CBC group. Functional recovery were significantly better with significantly lower inotropic requirements in HBS-S group than CBC group and HBS-L group. Although preoperative ejection fraction and C.I. were significantly lower in HBS-L group, post-operative cardiac function and inotropic requirements in HBS-L was comparable to that seen in CBC group. We conclude that the highly buffered histidine crystalloid cardioplegia solution provides effective myocardial preservation with a wider safety margin for prolonged myocardial preservation in open heart surgery.

A rapid and simple method for the determination of allantoin in pharmaceuticals by reversed-phase ion-pair high-performance liquid chromatography using an ODS column was presented. In general, it is difficult to retain allantoin to the ODS column owing to its very low hydrophobicity. We solved these problems by the use of a Tris-HCl buffer (pH 7.5) containing tetra-n-hexyl-ammonium bromide (THAB) as an ion-pair reagent for the mobile phase. Comparatively low concentrations of Tris-HCl buffer (0.9 mM) and THAB (0.5 mM) gave a high capacity factor (k'). As a results of the examination of the chromatographic behavior, it is confirmed that the retention mechanism of allantoin to the ODS column on the present method was not the ion-pair mode, but the ion-exchange mode. Calibration curves for allantoin showed a good linearity in the range of 10 to 400 micrograms/ml (r = 0.9999). The reproducibility (R.S.D., n = 6) was invariably good (0.37%). The lowest concentration of allantoin for the determination was 200 ng per 20 microliters of injection. The present method was successfully applied to the determination of allantoin in commercial eyedrops with good recovery (99.4%). It was found that allantoin in pharmaceuticals could be determined by the present method in short time and without any complicated derivatization.

Pressure overload hypertrophy has been known risk factor for open heart surgery, because of accelerated loss of high energy nucleotides, greater accumulation of H+ and lactate, and earlier onset of contracture. To test the efficacy of histidine containing cardioplegia (HB) on promotion of anaerobic glycolysis leads to improved preservation of hypertrophied heart, hypertrophied rabbit heart (aortic banding at 10 days) received HB or high potassium Krebs buffer solution (KCl) were subjected to 40 min of 37 degrees C ischemia followed by reperfusion in an isolated Langendorff mode. There was significantly higher phosphocreatine, intracellular pH and lactate production which was an indicator of anaerobic glycolysis and better recovery of cardiac function in HB group compared to KCl group. We concluded that histidine containing cardioplegia was able to promote anaerobic glycolysis to maintain high energy phosphates as well as contractile function in hypertrophied myocardium.

The buffering capacity of histidine in cardioplegia was analyzed from a viewpoint of anaerobic glycolysis and its end-products (lactate and alanine) by the myocardium. Isolated rabbit hearts were subjected to 3 hours multidose cardioplegic arrest by histidine (195 mM)-buffered or control solution at 21 degrees C and 30 minutes reperfusion. Diastolic pressure (DP) and recovery of developed pressure (DevP%) were measured with an intracavitary balloon filled to a pre-ischemic DP of 8-10 mmHg. Lactate and alanine in tissue and effluent were measured after ischemia by HPLC. The buffered solution group showed lower DP and higher DevP%, production of more lactate and alanine with diffusion of larger part of them into effluent than control group. We conclude that histidine in cardioplegia stimulates production of anaerobic glycolysis-derived high energy phosphate-compounds not only by proton buffering but also by removal of detrimental end-products out of the cell.

We studied the difference between congenital factor VIII deficient plasma and factor VIII immuno-depleted plasma on the effect of pre-dilution for factor VIII activity determined by the one-stage assay. When standard curves of one-stage assay for factor VIII: C by GEORGE KING factor VIII deficient plasma (frozen at -80 degrees C), BEHRING factor VIII deficient plasma (lyophilized), DADE factor VIII depleted plasma (lyophilized, von Willebrand factor antigen 0.2 U/ml) and DADE factor VIII depleted plasma (lyophilized, von Willebrand factor antigen 1.0 U/ml) were compared, the difference between the clotting times for 100% and 6.25% of activity in each reagent were 39.5, 29.5, 25.0, 23.0 seconds respectively. Potency values in concentrates without albumin or von Willebrand factor showed a discrepancy between pre-dilution in Owren-Koller buffer and pre-dilution in factor VIII deficient plasma. Potencies of those products pre-diluted in Owren-Koller buffer were 40-60% lower than potencies pre-diluted in factor VIII deficient plasma. These results showed substrate and pre-diluent must be chosen carefully for the accurate assay of factor VIII activity in vitro for the highly purified factor VIII concentrates.

The stability of allantoin was studied in pH 3.0, 6.0, and 8.0 buffer solutions at 50 degrees C for 55 d. Allantoin was determined by high performance liquid chromatography (HPLC) with a cation exchange mode and colorimetry. The known degradation compounds, allantoic acid and glyoxylic acid, were simultaneously determined by ion chromatography. Urea was determined by HPLC with an ion pair mode. In the stability studies on pH 6.0 and 8.0 solutions, new degradation compounds of allantoin were identified as two growing unknown peaks in the HPLC chromatogram. Isolation of these compounds by preparative HPLC and 1H, 15N and 13C-NMR spectra revealed that they were condensates of allantoin and glyoxylic acid, which also reacted positively in phenylhydrazine colorimetry. The amounts of these compounds were calculated from the determination results of other allantoin related compounds in the buffer solutions and were estimated as the biggest amount among all other compound. As they were found to be stable in an alkaline solution, conditions for hydrolysis in the colorimetric determination of allantoin were further examined. It was found that the longer hydrolysis gave more than 90% recovery in the colorimetry.

The purpose of this study was to investigate the relationship between the amount of fluoride in the enamel, taken from a fluoride-releasing sealant (F + sealant) and acid resistance. The F + sealant was applied to the bovine enamel from 1 week to 6 months. After the removal of the F + sealant, the bovine teeth were immersed in phosphate buffer from 1 month to 6 months. At each time period, the enamel was biopsied with acid and its fluoride and calcium concentration were analyzed. Results were as follows: (1) It was suitable to immerse the teeth in 1M KOH solution for 2 days in order to remove the loosely bound fluoride produced by the fluoride application from the enamel. (2) The amount of fluoride in the surface enamel increased in proportion to the application time of F + sealant. (3) The amount of calcium dissolved from the enamel showed the significant decrease by the F + sealant application, while no difference was shown by the application time. (4) The amount of fluoride in the surface enamel acquired by the F + sealant was maintained for 6 months after the removal of the F + sealant. (5) The amount of calcium dissolved from the enamel showed no difference in the period of immersion time.

The affects of acetic buffers on the crystallinity of an enamel apatite were examined in the present study. Dual aspects, crystallite size and lattice imperfection related to the crystallinity were analyzed by the process of Variance and Fourier analysis based on the X-ray diffraction line profiles. For this purpose both enamel apatite and synthetic hydroxyapatite were analyzed through acetic acid buffer decalcification, and comparison was made. In addition to the analysis, morphological change of the apatite after acid decalcification was observed by a transmission electron microscope (TEM). The results obtained in the present study were as follows: 1) Wedge-shaped defects formed on a prism plane were observed. In the further stage, wedge-shaped defects were also formed on a basal plane, and it proceeded into the center of the crystallite and consequentry slit similar to defected image was observed. 2) Lattice imperfection of the enamel and synthetic apatite were noticed both on the c-axis and a-axis. Among the factors which contributed to the variance, the "mistake" of lattice was much more likely than the crystallite size, and more mistakes in the direction of the a-axis rather than the c-axis was noticed. 3) A diminished crystallites size was found after acid treatment and diminishing on the c-axis was more apparent than the a-axis. 4) The crystallinity of the apatite was improved through acid treatment, and this improvement was attributed to a diminishing of mistakes. 5) Diminishing of mistakes through acid treatment was detected apparently along the c-axis. According to the results obtained in the present study, crystallite of enamel apatite showed decrease in size, although crystallinity through acid treatment was improved due to the diminishing of mistakes along the c-axis. This may be explained as following in that when apatite crystals were acid treated, the loci of lattice dislocation was selectively dissolved and consequently the more stable crystallite was left.