Levels of environmental contamination with SARS-CoV-2 in hospital rooms and salivary viral loads of patients with coronavirus disease 2019.

BACKGROUND: Clarifying the presence of viable severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rather than SARS-CoV-2 viral RNA in inpatient rooms is important for infection control of coronavirus disease 2019 (COVID-19). In this study, we investigated levels of viral RNA and viable virus on environmental surfaces and in patient saliva. METHODS: Environmental samples from 23 sites in hospital rooms were collected every other day until patient discharge. Saliva specimens and samples from the inner surface of patient masks were also collected. Additionally, environmental samples were collected from 46 sites in hospital rooms on discharge day. The samples were examined using quantitative reverse transcription polymerase chain reaction (RT-qPCR) and plaque assays. RESULTS: The 10 enrolled cases were classified as mild COVID-19, and patients were discharged after 6-9 days. The viral RNA was detected in 12.4% (105/849) of serially collected environmental samples during hospitalization, whereas viable virus was detected only in 0.47% (4/849), which were from sinks and tap levers. Although all patients recovered, three cases retained viable virus in the last saliva specimen collected. In the 15 discharged rooms, viral RNA was detected in 6.6% (45/682) of the samples, and viable virus was detected in only one sample from the sink. CONCLUSIONS: Although environmental surfaces surrounding patients with COVID-19 were frequently contaminated with viral RNA, the presence of viable virus was rare and limited only to areas around sinks. These results suggest that contact infection risk via fomites in hospital rooms is extremely rare.

Changes in oral health status in terminal cancer patients during the last weeks of life.

BACKGROUND: Many studies have shown deterioration of the oral health environment in palliative care patients; however, most of these studies are cross-sectional. In this longitudinal observational study, we aimed to determine the oral symptoms and how they change in palliative care patients. METHODS: The participants were 82 patients (37 men, 45 women) admitted to two palliative care units in Japan between January 2018 and December 2021. The oral condition was evaluated once a week from the time of admission using the Oral Health Assessment Tool (OHAT) and performance status (PS). Friedman tests were performed on the OHAT and PS scores at 1, 2, and 3 weeks before the week of death. In addition, the Bonferroni method was used to determine how many weeks before death the changes occurred. RESULTS: PS continuously deteriorated from three weeks before death. The total OHAT score 2 weeks before death (3.44±2.10) was significantly different compared to that in the week of death (4.37±2.45). In terms of oral conditions, the properties of the saliva changed, and dry mouth became obvious. CONCLUSIONS: The results of this study revealed that the oral environment of palliative care patients became significantly dry 2 weeks before death, suggesting that it may be useful for predicting the stage of death.

Visualization of airborne droplets generated with dental handpieces and verification of the efficacy of high-volume evacuators: an in vitro study.

BACKGROUND: The COVID-19 pandemic led to concerns about the potential airborne transmission of the virus during dental procedures, but evidence of actual transmission in clinical settings was lacking. This study aimed to observe the behavior of dental sprays generated from dental rotary handpieces and to evaluate the effectiveness of high-volume evacuators (HVEs) using laser light sheets and water-sensitive papers. METHODS: A dental manikin and jaw model were mounted in a dental treatment unit. Mock cutting procedures were performed on an artificial tooth on the maxillary left central incisor using an air turbine, a contra-angle electric micromotor (EM), and a 1:5 speed-up contra-angle EM (×5EM). Intraoral vacuum and extraoral vacuum (EOV) were used to verify the effectiveness of the HVEs. The dynamics and dispersal range of the dental sprays were visualized using a laser light sheet. In addition, environmental surface pollution was monitored three-dimensionally using water-sensitive papers. RESULTS: Although the HVEs were effective in both the tests, the use of EOV alone increased vertical dispersal and pollution. CONCLUSIONS: The use of various types of HVEs to reduce the exposure of operators and assistants to dental sprays when using dental rotary cutting instruments is beneficial. The study findings will be helpful in the event of a future pandemic caused by an emerging or re-emerging infectious disease.

Histopathological findings affect quantitative values of single photon emission computed tomography in patients with antiresorptive agent-related osteonecrosis of the jaws.

Objectives: This study investigated the relationships between quantitative values calculated from bone single photon emission computed tomography/computed tomography (SPECT/CT) images and histopathological findings observed in surgical specimens from patients with antiresorptive agent-related osteonecrosis of the jaw (ARONJ); it sought to clarify histopathological factors that cause accumulation in bone SPECT/CT images of patients with ARONJ. Methods: This study included 81 pathological specimens of 21 lesions obtained from 18 patients with ARONJ who underwent SPECT/CT and jaw resection. The maximum standardized uptake value (SUVmax) of each volume of interest of the specimens was calculated using RAVAT® software. The ratio of the SUVmax to the mean value of SUVmax in temporal bone was termed rSUVmax. The rSUVmax and pathological findings (sequestration, degree of fibrosis, degree of trabecular bone destruction, degree of inflammatory cell infiltration, and vascularity) were compared using the Mann-Whitney U test and the Kruskal-Wallis test. Results: In univariate analysis with rSUVmax as the dependent variable, the pathological findings of sequestration (P=0.058), degree of fibrosis (P=0.810), degree of trabecular bone destruction (P=0.237), degree of inflammatory cell infiltration (P=0.120), and vascularity (P=0.111) showed no significant difference among the groups for each variable. Conclusions: We found no association between quantitative values in bone SPECT/CT and histological changes in ARONJ, probably because bone SPECT/CT has limited spatial resolution. Limitations of this study may include the imaging findings of a decrease in tracer accumulation because of an involucrum of necrosed bone, various histopathological findings in ARONJ, and failure to consider the effect of preoperative anti-inflammatory treatment.

Evaluation of Velopharyngeal Closure Function With 4-Dimensional Computed Tomography and Assessment of Radiation Exposure in Pediatric Patients: A Cross-Sectional Study.

OBJECTIVE: Some patients with cleft palate (CP) need secondary surgery to improve functionality. Although 4-dimensional assessment of velopharyngeal closure function (VPF) in patients with CP using computed tomography (CT) has been existed, the knowledge about quantitative evaluation and radiation exposure dose is limited. We performed a qualitative and quantitative assessment of VPF using CT and estimated the exposure doses. DESIGN: Cross-sectional. SETTING: Computed tomography images from 5 preoperative patients with submucous CP (SMCP) and 10 postoperative patients with a history of CP (8 boys and 7 girls, aged 4-7 years) were evaluated. PATIENTS: Five patients had undergone primary surgery for SMCP; 10 received secondary surgery for hypernasality. MAIN OUTCOME MEASURES: The presence of velopharyngeal insufficiency (VPI), patterns of velopharyngeal closure (VPC), and cross-sectional area (CSA) of VPI was evaluated via CT findings. Organ-absorbed radiation doses were estimated in 5 of 15 patients. The differences between cleft type and VPI, VPC patterns, and CSA of VPI were evaluated. RESULTS: All patients had VPI. The VPC patterns (SMCP/CP) were evaluated as coronal (1/4), sagittal (0/1), circular (1/2), and circular with Passavant's ridge (2/2); 2 patients (1/1) were unevaluable because of poor VPF. The CSA of VPI was statistically larger in the SMCP group (P = .0027). The organ-absorbed radiation doses were relatively lower than those previously reported. CONCLUSIONS: Four-dimensional CT can provide the detailed findings of VPF that are not possible with conventional CT, and the exposure dose was considered medically acceptable.

Effect of morphological findings in computed tomography on the quantitative values in single-photon emission computed tomography for patients with antiresorptive agent-related osteonecrosis of the jaw: a cross-sectional study.

OBJECTIVE: Quantitative analyses of gamma-ray accumulation in single-photon emission computed tomography (SPECT), and the evaluation of antiresorptive agent-related osteonecrosis of the jaw (ARONJ) have been reported recently. However, the relationship between the quantitative parameters calculated from SPECT and the detailed morphological changes observed in computed tomography (CT) remains unclear. This study aimed to investigate patients' characteristics and morphological changes observed on CT, and their effects on the quantitative values in SPECT. METHODS: From April 2017 to March 2019, patients diagnosed with ARONJ at our hospital were enrolled. The data obtained before September 2017 were reviewed retrospectively, and other data were collected prospectively. CT scans were evaluated for internal texture, sequestrum formation, periosteal reaction, cortical perforation, bone expansion, and pathological fracture. For quantitative assessment, the ratio of the maximum standardized uptake value (SUV) to the mean SUV in the temporal bone (rSUVmax) was calculated from SPECT images. The factors affecting rSUVmax were investigated by multiple regression analysis. The statistical significance level was set at α = 0.05. RESULTS: Overall, 55 lesions of 42 patients (median age and interquartile range, 75 [67-80 years], 27 female) were evaluated. Male sex (p = 0.007) and bilateral location (p < 0.0001) were selected as variables in the multivariate analysis. Adjusted coefficient of determination R2 was 0.59 (p < 0.0001). CONCLUSION: Sex and horizontal progression of the disease may affect individually calibrated SUVs in SPECT for patients with ARONJ.

Two-versus three-dimensional regions of interest for quantifying SPECT-CT images.

The aim of this study was to investigate the relationship of quantitative parameters between the two-dimensional region of interest (ROI) and the three-dimensional volume of interest (VOI) for accumulation of radiopharmaceutical. Single-photon emission computed tomography combined with computed tomography (SPECT/CT) images of the NEMA/IEC phantom were acquired. The ROIs and VOIs were automatically set to the sphere and background in the phantom. We defined as two-dimensional analysis (2D analysis) that which used ROIs set on the center section of the sphere, and as three-dimensional analysis (3D analysis) that which used VOIs set on the center of gravity of the sphere. Dose linearity (DL), the recovery coefficient (RC), the contrast-to-noise ratio (CNR), and standardized uptake value (SUV) were evaluated. Each index value was compared between both analyses. DL was almost 1 under both conditions. RC showed a similar tendency with 2D and 3D analyses. The CNR for 3D analysis was smaller than for 2D analysis. The maximum SUV was almost equal with both analyses. The mean SUV with 3D analysis was underestimated by 4.83% on average compared with 2D analysis. For the same accumulation, a difference may occur in the quantitative index between 2 and 3D analyses. In particular, the quantitative parameters based on the average value tends to be smaller with 3D analysis than 2D analysis. The quantitative parameters in 2D analysis showed dependence upon the cross section used for setting the ROI, whereas 3D analysis showed less dependence on the position of the VOI.

Quantitative evaluation of anti-resorptive agent-related osteonecrosis of the jaw using bone single photon emission computed tomography in clinical settings: relationship between clinical stage and imaging.

OBJECTIVE: This study aimed to use quantitative values, calculated from bone single photon emission computed tomography (SPECT) imaging, to estimate the reliability of progression evaluation for anti-resorptive agent-related osteonecrosis of the jaw (ARONJ). METHODS: The study population consisted of 21 patients (23 lesions), clinically diagnosed with mandibular ARONJ, who underwent SPECT/CT scanning. Diagnosis and staging of ARONJ were performed according to the American Association of Oral and Maxillofacial Surgeons (AAOMS) definition and the recommendations of the International Task Force on ONJ. Hybrid SPECT/CT imaging quantitative analyses were performed on a workstation. Each volume of interest (VOI) was semi-automatically placed over a lesion with areas of high tracer accumulation, using the GI-BONE® software default threshold method settings. Additionally, control VOI was manually set over an unaffected area. Measured parameters included standardized uptake values (SUV)-maximum (SUVmax) and mean (SUVmean), metabolic bone volume (MBV)-the total volume above the threshold, and total bone uptake (TBU) as calculated by MBV × SUVmean. We also calculated the SUV ratio (rSUV) between the lesion and control area, factoring for differences in individual bone metabolism; the ratios were termed rSUVmax and rSUVmean, accordingly. The product of multiplying the rSUVmean by MBV of a lesion was defined as the ratio of TBU (rTBU). Quantitative values were compared between clinical stages by the Kruskal-Wallis test and subsequent post hoc analysis. RESULTS: MBVs (cm3) were: median, [IQR] Stage 1, 8.28 [5.62-9.49]; Stage 2, 15.28 [10.64-24.78]; and Stage 3, 34.61 [29.50-40.78]. MBV tended to increase with stage increase. Furthermore, only MBV showed a significant difference between clinical stages (p < 0.01). Subsequent post hoc analysis showed no significant difference between stages 1 and 2 (p = 0.12) but a significant difference between stages 2 and 3 (p = 0.048). rSUVmax and rTBU tended to increase with stage increase, but the differences between the stages were not significant (p = 0.10 and p = 0.055, respectively). CONCLUSION: MBV, which includes the concept of volume, showed significant differences between clinical stages and tended to increase with the stage increase. As an objective and reliable indicator, MBV might be an adjunct diagnostic method for staging ARONJ.

Generating Silicon Nanofiber Clusters from Grinding Sludge by Millisecond Pulsed Laser Irradiation.

Silicon nanofiber clusters were successfully generated by the irradiation of millisecond pulsed laser light on silicon sludge disposed from wafer back-grinding processes. It was found that the size, intensity, and growing speed of the laser-induced plume varied with the gas pressure, while the size and morphology of the nanofibers were dependent on the laser pulse duration. The generated nanofibers were mainly amorphous with crystalline nanoparticles on their tips. The crystallinity and oxidation degree of the nanofibers depended on the preheating conditions of the silicon sludge. This study demonstrated the possibility of changing silicon waste into functional nanomaterials, which are possibly useful for fabricating high-performance lithium-ion battery electrodes.

Velopharyngeal closure analysis using four-dimensional computed tomography: a pilot study of healthy volunteers and adult patients with cleft palate.

BACKGROUND: Nasopharyngoscopy is a common method to evaluate velopharyngeal closure in patients with cleft palate. However, insertion of a fiberoptic nasopharyngoscope causes discomfort in patients. The aim of this study was to estimate the reliability of short-time exposure images obtained using 320-row area detector computed tomography (320-ADCT) as a novel evaluation method for the assessment of velopharyngeal function. METHODS: We evaluated five healthy adult volunteers and five postoperative adult patients with cleft palate. During a 3.3-s imaging exposure, the participants were asked to perform two tasks: nasal inspiration and subsequent oral expiration through a catheter into a water-filled cup. The movement of the velopharyngeal structures was recorded during each examination, and the presence of velopharyngeal insufficiency (VPI) and velopharyngeal closure (VPC) patterns were estimated. If VPI was detected, the cross-sectional area was also calculated. Cohen's kappa and weighted kappa coefficients were used to evaluate the concordance of nasopharyngoscopy and 320-ADCT evaluation. RESULTS: Speech pathology evaluation did not reveal hypernasality in any study participant. Micro-VPI was detected by nasopharyngoscopy in one healthy volunteer and two patients. 320-ADCT detected micro-VPI in two more patients. The cross-sectional area of the VPI in these subjects ranged from 2.53 to 16.28 mm2. Nasopharyngoscopy and 320-ADCT were concordant in detecting VPI in eight participants (κ = 0.6) and in assessing VPC patterns in nine (κ = 0.82). Moreover, images obtained using 320-ADCT allowed for reduced dead angle and, thus, easy detection of micro-VPI and Passavant's ridges. CONCLUSION: Although the radiation exposure cannot be ignored, our novel evaluation method using 320-ADCT enables more detailed evaluation of VPC than nasopharyngoscopy. Future studies should investigate the relationship between 320-ADCT findings and speech pathology evaluations.

Clinical evaluation of postoperative nausea and vomiting after cleft lip and/or palate surgery in pediatric patients. Part 2: evaluation of preventive administration of droperidol in combination with dexamethasone.

OBJECTIVES: This study aimed to evaluate the effect of preventive administration of the combination of droperidol and dexamethasone on lowering the risk for postoperative nausea and vomiting (PONV) after cleft-related surgery in pediatric patients. METHODS: Preventive care consisted of a single dose of droperidol (0.025 mg/kg) and dexamethasone (0.06 mg/kg), which were administered at the end of surgery. The effect of preventive administration was evaluated in a sample group of 58 patients aged ≥3 years who underwent cleft-related surgery. Thirty patients received preventive administration (prevention group) and 28 patients did not (comparative group). The following outcome variables were evaluated between the groups: sex, age, body weight at the time of surgery, and duration of anesthesia. The presence or absence of PONV was the primary outcome and other variables were considered as explanatory variables. RESULTS: The incidence rate of PONV was 20% (6/30) in the prevention group and 28.6% (8/28) in the comparative group, with no significant difference between the groups (p=0.45). In multiple logistic regression analysis, sex was the only explanatory factor of PONV, with a higher risk in girls than in boys (odds ratio, 6.20; 95% confidence interval, 1.65-27.63; p=0.01). CONCLUSIONS: The incidence rate of PONV is 20% with preventive care of droperidol and dexamethasone administration, but this rate is not different from that without this combination. Sex is a risk factor for PONV. Further studies are required to validate our results.

Osteogenesis Imperfecta Diagnosed from Mandibular and Lower Limb Fractures: A Case Report.

Osteogenesis imperfecta (OI) is a congenital disease characterized by bone fragility and low bone mass. Despite the variety of its manifestation and severity, facial fractures occur very infrequently. Here, we report a case of an infant diagnosed with OI after mandibular and lower limb fractures. A boy aged 1 year and 3 months was brought to his neighboring hospital with a complaint of facial injury. He was transferred to our hospital to undergo operation 3 days later. Computed tomography images revealed multiple mandibular fractures including complete fracture in the symphysis and dislocated condylar fracture on the right side. Open reduction and internal fixation with absorbable implants was performed 7 days after injury. He fractured his right lower limb 2 months later. He was diagnosed with OI type IA by an orthopedist. He will be administered bone-modifying agents if he suffers from frequent fractures.

Appropriate Tongue Blade Length of the Dingman Mouth Gag for Japanese Pediatric Patients With Cleft Palate and Mandibular Micrognathia.

Objective Our objective is to determine appropriate specifications for smaller tongue blade for Japanese pediatric patients with cleft palate (CP) and mandibular micrognathia. Patients We investigated 59 patients who underwent palatoplasty. Patients were divided into two groups: the micrognathia (MG) group consisted of 11 patients and the normognathia (NG) group consisted of 48 patients. Interventions The following five items were investigated retrospectively: (1) gender, (2) cleft type, (3) age at the time of surgery, (4) weight at the time of surgery, and (5) distance from the tongue blade base to the posterior pharyngeal wall (Dis). Results There was a significant difference (P < .01) in age at the time of surgery and in Dis between groups, but not in weight. The minimum values were 55 mm for the MG group. As for correlations between age and weight at the time of surgery, the P values for the MG and NG groups were .993 and .052, respectively. As for correlations between weight at the time of surgery and Dis, the P values for the MG and NG groups were .987 and .099, respectively. Conclusions It was difficult to predict Dis on the basis of the patient's age and weight measured preoperatively. The minimum Dis was 55 mm, equal to the length from the base to the tip of the Dingman Mouth Gag tongue blade currently in use, suggesting that a tongue blade of approximately 50 mm in length, shorter than the current minimum specifications, may be appropriate.

Local recurrence of sclerosing mucoepidermoid carcinoma with eosinophilia in the upper lip: a case report.

INTRODUCTION: Sclerosing mucoepidermoid carcinoma with eosinophilia is a rare morphological variant of thyroid carcinoma associated with Hashimoto's disease. To date, only three such tumors have been reported in the minor salivary glands. We describe the first case, to the best of our knowledge, of recurrent sclerosing mucoepidermoid carcinoma with eosinophilia in the minor salivary glands of the upper lip. CASE PRESENTATION: A 61-year-old Japanese man was referred to our hospital with a mass in his median upper lip of four years' duration. An examination of his median upper lip revealed a well-defined tumor measuring 9 × 12 mm in diameter, which was subsequently resected. Three years after the first surgery, the tumor recurred and was resected. Both tumors were confirmed by histopathology to be sclerosing mucoepidermoid carcinoma with eosinophilia. Neither recurrence nor metastasis was observed in three and a half years of follow-up after the second surgery. CONCLUSION: Our findings indicate that sclerosing mucoepidermoid carcinoma with eosinophilia can originate in the minor salivary glands and may be clinically or pathologically misdiagnosed as other conditions.

Safety, tolerability, pharmacokinetics and antitumor activity of ganitumab, an investigational fully human monoclonal antibody to insulin-like growth factor type 1 receptor, combined with gemcitabine as first-line therapy in patients with metastatic pancreatic cancer: a phase 1b study.

OBJECTIVE: Previous Phase 1 studies have shown the acceptable safety profile of ganitumab-a fully human monoclonal antibody to insulin-like growth factor Type 1 receptor-in patients with advanced solid tumors. However, ganitumab 20 mg/kg in combination with gemcitabine had not been administered to patients with metastatic pancreatic cancer. To evaluate the safety, tolerability, pharmacokinetics and antitumor activity of ganitumab 20 mg/kg combined with gemcitabine 1000 mg/m(2) as first-line therapy in patients with metastatic pancreatic cancer, we conducted a Phase 1b study. METHODS: Eligible patients were adults with previously untreated metastatic adenocarcinoma of the pancreas. Patients received gemcitabine 1000 mg/m(2) on Days 1, 8 and 15 plus ganitumab 20 mg/kg on Days 1 and 15 of each 28-day cycle. Gemcitabine was administered intravenously over 30-60 min. Ganitumab was administered intravenously over 60 min after completing gemcitabine infusion. RESULTS: Six patients were enrolled and received the study treatment. All patients had thrombocytopenia and leukopenia. Other most common adverse events were neutropenia and nausea. One patient had a dose-limiting toxicity defined as Grade 3 neutropenia with fever. Exposure to ganitumab 20 mg/kg was not affected by the administration of gemcitabine. No apparent pharmacokinetic drug-drug interaction was observed. No anti-ganitumab antibodies were detected. Five patients had a measurable tumor region at baseline. Of these, four patients had a best response of stable disease. CONCLUSIONS: Ganitumab 20 mg/kg combined with gemcitabine 1000 mg/m(2) was tolerable and showed an acceptable safety profile in patients with untreated metastatic pancreatic cancer.

A new method for evaluating the bitterness of medicines in development using a taste sensor and a disintegration testing apparatus.

The purpose of this study was to demonstrate the usefulness and wide applicability of a taste sensor and a new disintegration testing apparatus in the development and/or evaluation of orally disintegrating tablets (ODTs). In this paper, we described methods for the effective utilization of a taste sensor in the development of a new medicine. First we predicted the taste of propiverine hydrochloride, a model drug substance whose taste is unknown, using a taste sensor. Then we screened masking agents for their ability to suppress the bitterness of propiverine hydrochloride, and manufactured ODTs of propiverine hydrochloride with various masking agents. The tastes of these ODTs were then evaluated in chronological order by combining the taste sensor with the new disintegration testing apparatus, ODT-101, to resemble the oral cavity. As a result, we were able to evaluate the taste of propiverine hydrochloride and the effectiveness of various masking agents in ODTs. The result using this combination of taste sensor and ODT-101 shows good agreement with the results of human gustatory sensation testing, thus demonstrating the usefulness and applicability of the taste sensor and disintegration testing apparatus, ODT-101, in the development of new medicine.

Advanced taste sensors based on artificial lipids with global selectivity to basic taste qualities and high correlation to sensory scores.

Effective R&D and strict quality control of a broad range of foods, beverages, and pharmaceutical products require objective taste evaluation. Advanced taste sensors using artificial-lipid membranes have been developed based on concepts of global selectivity and high correlation with human sensory score. These sensors respond similarly to similar basic tastes, which they quantify with high correlations to sensory score. Using these unique properties, these sensors can quantify the basic tastes of saltiness, sourness, bitterness, umami, astringency and richness without multivariate analysis or artificial neural networks. This review describes all aspects of these taste sensors based on artificial lipid, ranging from the response principle and optimal design methods to applications in the food, beverage, and pharmaceutical markets.

Evaluation of the bitterness of antibiotics using a taste sensor.

The bitterness of nine commercial antibiotics (clarithromycin, erythromycin, cefdinil, doxycycline, vancomycin, tetracycline, minocycline, oxytetracycline and bacampicillin) was evaluated in human gustatory sensation tests with nine volunteers. The bitterness of 0.1-0.3 mM solutions (or suspensions in the case of clarithromycin) of the antibiotics was then measured using an artificial multichannel taste sensor. In the sensor measurements, three variables were used to predict estimated bitterness in single and multiple regression analysis and principal component analysis: sensor output as relative value (R), the change of membrane potential caused by adsorption (C) and C/R. Particularly good correlation was obtained between obtained bitterness scores and predicted scores using C from channel 2 of the sensor (r2=0.870, P<0.005) and C/R values for channels 2 and 3 (r2=0.947, P<0.005). The taste sensor was also successful in assessing the bitterness intensity of clarithromycin powder suspensions of various concentrations. Clarithromycin has a low aqueous solubility but is the most bitter of the nine antibiotics. Sensory data from channel 3 of the sensor predicted the bitterness of clarithromycin powder suspensions and their filtered solutions well. Finally, the bitterness intensity of a commercial clarithromycin dry syrup product (Clarith dry syrup, Taisho Pharmaceutical Co. Ltd, Tokyo, Japan) was evaluated in gustatory sensation tests and using the taste sensor. In Clarith dry syrup the drug is coated with aminoalkyl methacrylate polymer using a spray congealing method. The taste sensor results confirmed that the polymer was successful in almost completely masking the bitter taste of the dry syrup product.

Prediction of the bitterness of single, binary- and multiple-component amino acid solutions using a taste sensor.

The purpose of this study was to develop a quick, quantitative, prediction method for the determination of the bitterness of solutions containing one or more of five amino acids (L-isoleucine, L-leucine, L-valine, L-phenylalanine, and L-tryptophan), using an artificial taste sensor. The bitterness of various solutions containing different concentrations (1, 3, 10, 30, and 100 mM) of five amino acids, singly and in combination, was estimated using a multichannel taste sensor and compared with the results of human gustatory sensation tests with nine volunteers. The relative response electric potential patterns were similar for all five amino acids. Large sensor outputs were observed in channels 1-4 (which are negatively charged) while there were no responses in channels 5-8 (positively charged). The sensor output for channel 1, which was the largest output value, was used for prediction of bitterness. The change of membrane potential caused by adsorption (CPA), which corresponds to aftertaste, could not be used as an explanatory variable since the adsorption of the amino acids to the sensor membrane was weak and CPA values were small. The bitterness intensity scores for single, binary, and multi-component amino acid solutions, could be easily predicted on the basis of the sensor output value of channel 1 using regression analysis. Principal component analysis of the sensor output data suggested that the sourness, astringency and/or smell of the solutions also played a role in the perception of bitterness.