Use of Japanese big data from electronic medical records to investigate risk factors and identify their high-risk combinations for linezolid-induced thrombocytopenia

PURPOSE

Thrombocytopenia is a major event associated with linezolid (LZD) therapy. Factors affecting LZD-induced thrombocytopenia (LIT) have been reported in previous studies. However, several issues pertaining to LIT have not yet been clarified. In the present study, we used Japanese big data to investigate associated factors and their high-risk combinations that influence LIT.

METHODS

Patients administered LZD between May 2006 and October 2020 were included in this study. LIT was defined as either a 30% or more reduction from the baseline platelets or platelet values of < 100,000/µL. We evaluated factors affecting LIT and combinations of factors that alter LIT risk according to a decision tree (DT) analysis, a typical machine learning method.

RESULTS

We successfully enrolled 1399 patients and LIT occurred in 44.7% of the patients (n = 626). We classified the laboratory data on renal function, LZD duration, age, and body weight (BW) into smaller categories. The results of multivariate analysis showed that prolonged LZD therapy, BW < 45 kg, estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73 m², and dialysis were risk factors for LIT. The DT analysis revealed that the highest risk was a combination of LZD duration ≥ 14 days and eGFR < 30 mL/min/1.73 m².

CONCLUSIONS

The present study extracted four risk factors and identified high-risk combinations for LIT. Patients with these risk factors should be closely monitored.

Risk Factor Analysis of Vancomycin-Induced Nephrotoxicity in Paediatric Patients Aged 0-1 Year Using Japanese Medical Database

Vancomycin (VCM)-induced nephrotoxicity (VIN) is a major side effect in paediatric patients. However, most studies are limited to patients aged 0-18 years. We evaluated the risk factors of VIN in patients aged 0-1 year using Japanese electronic medical record database. We used RWD database which was contained electronic medical records and claims data of approximately 20 million people from 160 medical institutions. We targeted hospitalized patients who were administered VCM between June 2000 and December 2020. VIN was defined by two criteria: Criterion 1 was an increase in serum creatinine (Scr) ≥ 0.5 mg/dL or 50% during VCM treatment period compared to the Scr baseline; and criterion 2 was an increase in Scr ≥50% within seven days or Scr ≥0.3 mg/dL within two days during VCM treatment. The risk factors of VIN were evaluated using multivariate logistic regression analysis. We analysed 446 patients; patients with VIN in Criteria 1 and 2 were 33 and 58, respectively. In Criterion 1, multivariate logistic regression analysis identified four independent factors with p-value <0.05 (VCM concentration ≥20 mg/L, amphotericin B (AMPH-B), piperacillin-tazobactam (TAZ/PIPC), and vasopressor drugs). In Criterion 2, multivariate logistic regression analysis identified concomitant use of vasopressor drugs with p-value <0.05. Therefore, concomitant use of vasopressor drugs was suggested to affect the risk of VIN in patients aged 0-1 year. The findings may help in developing estimation models to assess the risk of VIN in paediatric patients.

Urinary Protein-to-creatinine Ratios Predict Recurrence in Pediatric and Young Adult Cases of Minimal Change Nephrotic Syndrome

High-dose steroids are required for the treatment of minimal change nephrotic syndrome (MCNS), especially for episodes of recurrence. Predicting and avoiding recurrence can help reduce the steroid dose, but prediction is currently difficult. We herein examined whether changes in laboratory data, especially the urinary protein- to-creatinine ratio (UTP/UCr), can predict clinical recurrence. We also assessed differences in clinical features between children and young adults. We included 36 patients with MCNS; for each case, we retrospectively studied laboratory data during stable remission and pre-recurrence, with the "stable" period defined as all but the 6 weeks before recurrence, and pre-recurrence defined as the 4±2 weeks before recurrence. UTP/UCr, serum albumin, etc. were measured every 5 years during stable periods. We divided patients into cohorts by age at recurrence, < 15 years and ≥ 15 years, and compared stable and pre-recurrence values for the two groups. UTP/UCr values during stable periods tended to be higher in younger patients. UTP/UCr and serum albumin showed statistically significant changes during pre-recurrence periods, but only in those aged ≥ 15 years. Thus, clinical features of recurrence differed depending on age. Signs of recurrence can be confirmed via UTP/UCr or serum albumin several weeks before recurrence in patients ≥ 15 years.

Using Japanese big data to investigate novel factors and their high-risk combinations that affect vancomycin-induced nephrotoxicity

AIMS

Several factors related to vancomycin-induced nephrotoxicity (VIN) have not yet been clarified. In the present study, we used Japanese big data to investigate novel factors and their high-risk combinations that influence VIN.

METHODS

We employed a large Japanese electronic medical record database and included patients who had been administered intravenous vancomycin between June 2000 and December 2020. VIN was defined as an increase in serum creatinine ≥0.5 mg/dL or 1.5-fold higher than the baseline. The outcomes were: (1) factors affecting VIN that were identified using multiple logistic regression analysis, and (2) combinations of factors that affect the risk of VIN according to a decision tree analysis, which is a typical machine learning method.

RESULTS

Of the 7,306 patients that were enrolled, VIN occurred in 14.2% of them (1,035). A multivariate analysis extracted 22 variables as independent factors. Concomitant ramelteon use (odds ratio; 0.701, 95% confidence interval; 0.512-0.959), ward pharmacy service (0.741, 0.638-0.861), duration of VCM <7 days (0.748, 0.623-0.899) and trough concentrations 10-15 mg/L (0.668, 0.556-0.802) reduce the risk of VIN. Meanwhile, concomitant piperacillin-tazobactam use (2.056, 1.754-2.409) and piperacillin use (2.868, 1.298-6.338) increase the risk. The decision tree analysis showed that a combination of vancomycin trough concentrations ≥20 mg/L and concomitant piperacillin-tazobactam use was associated with the highest risk.

CONCLUSIONS

We revealed that the concomitant ramelteon use and ward pharmacy service may decrease the risk of VIN, while the concomitant use of not only piperacillin-tazobactam but also piperacillin may increase the risk.

Implementation Status of Liver Function Tests for Monitoring Benzbromarone-Induced Hepatotoxicity: An Epidemiological Survey Using the Japanese Claims Database

A major adverse effect of benzbromarone is hepatotoxicity. Therefore, periodic liver function tests are required at least for the first 6 months of benzbromarone administration. However, it is not clear whether the relevant blood tests are implemented appropriately. Here, we performed a cross-sectional survey of the implementation status of liver function tests in patients who were newly prescribed benzbromarone, using the Japanese large claims database. Male patients who were newly prescribed benzbromarone from January 2010 to December 2016 were included. We targeted patients who continued benzbromarone during the observation period (up to 180 d from the start of administration). The primary endpoint was the proportion of patients in whom periodic liver function tests were implemented. A periodic liver function test was defined as one or more liver function tests performed during both 1-90 and 91-180 d of initial benzbromarone administration. We labeled the tests as a "periodic test" or "non-periodic test" based on whether periodic liver function tests were performed or not, respectively. Furthermore, factors influencing non-periodic test were analyzed. Periodic testing was implemented only in 28.7% of patients. Additionally, factors such as number of hospital beds ≤19 (compared to 100-199 beds) and duration of the first prescription of benzbromarone were associated with non-periodic testing. Our study revealed that periodic liver function tests are not performed sufficiently in Japan. Thus, clinicians prescribing benzbromarone should be educated about the test. Our blood-test-based approach should be applied to other drugs and countries in future research.

Factors affecting creatine phosphokinase elevation during daptomycin therapy using a combination of machine learning and conventional methods

AIMS

Musculoskeletal toxicity is a typical side effect of daptomycin (DAP). However, the risk factors have not been well established. Here, we aimed to identify independent factors affecting DAP-induced musculoskeletal toxicity using a combination of machine learning and conventional statistical methods.

METHODS

A population-based, retrospective, observational cohort study was conducted using the Japanese electronic medical record database. Patients who received DAP between October 2011 and December 2020 were enrolled. Two definitions of musculoskeletal toxicity were employed: (1) elevation of creatine phosphokinase (CPK) value more than twice from baseline and >200 IU/L, and (2) >1000 IU/L. First, multiple logistic regression analyses (a conventional statistical method) were performed to identify independent factors affecting CPK elevation. Then, decision tree analyses, a machine learning method, were performed to detect combinations of factors that change CPK elevation risk.

RESULTS

Of the 2970 patients who received DAP, 706 were included. Elevation of CPK values >200 IU/L and >1000 IU/L occurred in 83 (11.8%) and 17 (2.41%) patients, respectively. In multiple logistic regression analysis, baseline CPK value and concomitant use of hydrophobic statins were commonly extracted as independent factors affecting each CPK elevation, but concomitant use of hydrophilic statins was not. In decision tree analysis, patients who received hydrophobic statins and had high baseline CPK values were classified into the high-risk group.

CONCLUSION

Our novel approach revealed new risk factors for CPK elevation. Our findings suggest that high-risk patients require frequent CPK monitoring.

A cross-sectional survey of hospitalization and blood tests implementation status in patients who received tolvaptan under 75 years of age using a Japanese claims database

BACKGROUND

Hypernatremia and liver injury are typical adverse effects of tolvaptan. Therefore, hospitalization and frequent monitoring of serum sodium concentration and liver function are necessary for tolvaptan initiation. We performed a cross-sectional survey to evaluate these situations.

RESEARCH DESIGN AND METHODS

We employed the Japanese claims database, which contains data of patients aged < 75 years. Patients who were newly prescribed tolvaptan for fluid accumulation induced by chronic heart failure (FA-CHF) or liver cirrhosis (FA-LC) from January 2011 to June 2017 were included. We evaluated the hospitalization status and implementation of serum sodium and liver function tests in the evaluation period, based on the Japanese package insert.

RESULTS

Of 1,173 patients, 347 and 117 were enrolled in FA-CHF and FA-LC groups, respectively. Among them, 10.7% (FA-CHF group) and 5.13% (FA-LC group) were prescribed tolvaptan without hospitalization. In the FA-CHF group, 11.0% and 17.6% did not undergo serum sodium and liver function tests even once in the evaluation period, respectively, compared with 12.0% and 12.8% in the FA-LC group.

CONCLUSIONS

Our results highlight the deviation from Japanese package insert recommendations. This approach can be applied to other drugs and provides important perspectives on pharmacovigilance research.

Probiotic Prescription Status of Pediatric Patients with Otitis Media Receiving Oral Amoxicillin or Amoxicillin/Clavulanate from April 2016 to March 2017 Using a Japanese Health Insurance Claims Database

Antibiotic-associated diarrhea (AAD) is a typical side effect of antibiotic treatment, especially in children. Amoxicillin (AMPC) and amoxicillin/clavulanate (AMPC/CVA) are associated with high risk of AAD; however, these antibiotics are important in the pediatric field. Recent research suggests that probiotics prevent pediatric AAD, including that caused by AMPC and AMPC/CVA. Indeed, guidelines for acute otitis media in children recommend the concomitant use of probiotics. However, the prescription status of probiotics for pediatric patients with otitis media receiving oral AMPC and AMPC/CVA remains unknown. We therefore conducted a survey to clarify the current status of these prescriptions and, in particular, to identify specific populations with a low proportion of probiotic prescriptions. Pediatric patients (≤15 years of age) newly prescribed oral AMPC or AMPC/CVA for otitis media between April 2016 and March 2017 were identified from a Japanese health insurance claims database. Eligible patients were divided into the AMPC (1303 patients) and AMPC/CVA (424 patients) groups, in which 659 (50.6%) and 293 (69.1%) patients were prescribed probiotics, respectively. Of the patients receiving probiotic prescriptions in the AMPC and AMPC/CVA groups, 632 (95.9%) and 286 (97.6%) patients received antibiotic-resistant probiotic prescriptions, respectively. When classified by the prescribing clinical department and patient age, the proportions of probiotic prescriptions in Internal Medicine and Pediatrics departments were lower than those in the Otorhinolaryngology department regardless of age. These results indicate the probability of insufficient probiotic prescriptions for pediatric patients with otitis media. Solving this issue may lead to the provision of safer antimicrobial therapy.

A New Algorithm Optimized for Initial Dose Settings of Vancomycin Using Machine Learning

This study aimed to construct an optimal algorithm for initial dose settings of vancomycin (VCM) using machine learning (ML) with decision tree (DT) analysis. Patients who were administered intravenous VCM and underwent therapeutic drug monitoring (TDM) at the Hokkaido University Hospital were enrolled. The study period was November 2011 to March 2019. In total, 654 patients were included in the study. Patients were divided into two groups, training (patients who received VCM from November 2011 to December 2017; n = 496) and testing (patients who received VCM from January 2018 to March 2019; n = 158) groups. For the training group, DT analysis of the classification and regression tree algorithm was performed to construct an algorithm (called DT algorithm) for the initial dose settings of VCM. For the testing group, the rates of attaining the VCM therapeutic range (trough value = 10-15 and 10-20 mg/L) with the DT algorithm and three conventional dose-setting methods were compared for model evaluation. The DT algorithm was constructed to be used for patients with estimated glomerular filtration rate ≥50 mL/min and body weight ≥40 kg. As a result, the recommended daily doses ranged from 20.0 to 58.1 mg/kg. In model evaluation, the DT algorithm obtained the highest rates of attaining the VCM therapeutic range compared to conventional dose-setting methods. Therefore, our DT algorithm can be applied to clinical practice. In addition, ML is useful for setting drug doses.

Association of the ward pharmacy service with active implementation of therapeutic drug monitoring for vancomycin and teicoplanin-an epidemiological surveillance study using Japanese large health insurance claims database

Background

Ward pharmacists are required for the active implementation of therapeutic drug monitoring (TDM). This epidemiological study verified whether Japanese ward pharmacists contribute to improving the TDM implementation proportions of anti-methicillin-resistant Staphylococcus aureus (MRSA) agents using the large health insurance claims database.

Methods

The patients who received intravenous anti-MRSA agents from April 2012 to March 2017 were enrolled. We defined ward pharmacy service as the “drug management and guidance fee” and/or “inpatient pharmaceutical services premium”. In addition, implementation of TDM was identified by “the specific drug treatment management fee”. We compared the proportions of TDM implementation for vancomycin (VCM), teicoplanin (TEIC), and arbekacin (ABK) in the ward and non-ward pharmacy service groups. To avoid confounding, the propensity score method was employed. Moreover, the clinical variables affecting TDM implementation in each anti-MRSA agent were analyzed by using a multiple logistic regression model.

Results

The following number of patients were included in the study: VCM (n = 2138), TEIC (n = 596), and ABK (n = 142). After propensity score matching, the proportions of TDM implementation for VCM and TEIC were higher in the ward pharmacy service group than in the non-ward pharmacy service group (VCM: 69.2% vs 60.3%, TEIC: 51.4% vs 34.7%), while no significant difference was observed for ABK (21.2% vs 23.1%). As independent clinical variables affecting TDM implementation for VCM and TEIC, several clinical variables, including ward pharmacy services, were extracted. In contrast, no clinical variables were extracted for ABK.

Conclusions

We found that the ward pharmacy service is associated with the active implementation of TDM for anti-MRSA agents, such as VCM and TEIC.

Comparison of interactions between warfarin and cephalosporins with and without the N-methyl-thio-tetrazole side chain

Cephalosporins with an N-methyl-thio-tetrazole (NMTT) side chain interact with warfarin by reducing the production of blood clotting factors. However, cephalosporins without the NMTT side chain also enhance the effects of warfarin. Thus, we aimed to compare the effects of warfarin modified by cephalosporins with and without the NMTT side chain, using a Japanese health insurance claims database. The inclusion criteria were patients who (1) intravenously received second- or third-generation cephalosporins between April 2010 and March 2017 and (2) received warfarin during cephalosporin therapy. Patients were administered either cephalosporins with the NMTT side chain (NMTT group) or those without NMTT (non-NMTT group). After matching patient data by propensity score, the following outcomes were compared between the two groups: (1) proportion of patients administered vitamin K, (2) proportion of bleeding events, and (3) changes in the daily dose of warfarin. Among 203 patients, 100 patients (50 per group) were matched by the propensity score. The proportion of patients administered vitamin K was 6.0% in both groups. These patients intravenously received a single dose of menatetrenone; no bleeding was observed. The proportion of patients subjected to a reduction in the daily dose of warfarin was 6.5% and 4.3% in the NMTT and non-NMTT groups, respectively. As our study had a small sample size, we could not determine whether the risk of over anticoagulation of warfarin is affected by cephalosporins with or without NMTT side chain. However, we showed the bleeding risk was sufficiently low regardless of the presence/absence of the NMTT side chain.

Validation of the usefulness of artificial neural networks for risk prediction of adverse drug reactions used for individual patients in clinical practice

Artificial neural networks are the main tools for data mining and were inspired by the human brain and nervous system. Studies have demonstrated their usefulness in medicine. However, no studies have used artificial neural networks for the prediction of adverse drug reactions. We aimed to validate the usefulness of artificial neural networks for the prediction of adverse drug reactions and focused on vancomycin -induced nephrotoxicity. For constructing an artificial neural network, a multilayer perceptron algorithm was employed. A 10-fold cross validation method was adopted for evaluating the resultant artificial neural network. In total, 1141 patients who received vancomycin at Hokkaido University Hospital from November 2011 to February 2019 were enrolled. Among these patients, 179 (15.7%) developed vancomycin -induced nephrotoxicity. The top three risk factors of vancomycin -induced nephrotoxicity which are relatively important in the artificial neural networks were average vancomycin trough concentration ≥ 13.0 mg/L and concomitant use of piperacillin–tazobactam and vasopressor drugs. The predictive accuracy of the artificial neural network was 86.3% and that of the multiple logistic regression model (conventional statistical method) was 85.1%. Moreover, area under the receiver operating characteristic curve (AUROC) of the artificial neural network was 0.83. In the 10-fold cross-validation, the accuracy obtained was 86.0% and AUROC was 0.82. The artificial neural network model predicting the vancomycin -induced nephrotoxicity showed good predictive performance. This appears to be the first report of the usefulness of artificial neural networks for an adverse drug reactions risk prediction model.

Nonsteroidal anti-inflammatory drugs use in patients with chronic kidney disease are often prescribed from different clinicians than those who diagnosed them

PURPOSE

When prescribing nonsteroidal anti-inflammatory drugs (NSAIDs) for chronic kidney disease (CKD), patients' pathology and concomitant medications should be considered. In our pharmaceutical experience, NSAIDs are often prescribed by departments that are different from those that diagnosed CKD. That is, NSAIDs may be prescribed for patients without the advice of the clinicians who diagnosed them. In this study, we aimed to elucidate how frequently such cases occur.

METHODS

We used the large health insurance claims database constructed by JMDC Inc., Tokyo. We evaluated the proportions of CKD diagnosis and NSAID prescription by different clinical departments and institutions.

RESULTS

A total of 224 014 out-patients were included in the analysis; they were divided into CKD (n = 1501) and non-CKD groups (n = 222 513). The internal medicine departments diagnosed CKD most frequently (74.8% of the patients) and surgical departments rarely diagnosed CKD. However, the proportion of prescribed NSAIDs was high in other departments, especially surgical departments. In the CKD group, 50.4% of the patients received CKD diagnosis and NSAID prescription from different clinical departments; 72.8% of the patients received a diagnosis and prescription from different medical institutions.

CONCLUSION

Our study revealed that NSAIDs are often prescribed to patients with CKD from different clinicians than those who diagnosed them.

Individualized concept for the treatment of autosomal recessive polycystic kidney disease with end-stage renal disease

Management of children with autosomal recessive polycystic kidney disease (ARPKD) who develop end-stage renal disease (ESRD) remains challenging because of concomitant liver disease. Patients with recurrent cholangitis are candidates for liver-kidney transplantation, while the treatment for patients with splenomegaly and pancytopenia due to portal hypertension is controversial. Herein, we report 7 children who were treated using an individualized treatment strategy stratified by liver disease. Two patients with recurrent cholangitis underwent sequential liver-kidney transplantation, while 4 patients with splenomegaly and pancytopenia but without recurrent cholangitis underwent splenectomy followed by isolated kidney transplantation. The remaining patient, who did not have cholangitis and pancytopenia, underwent isolated kidney transplantation. Blood cell counts were normalized after splenectomy was performed at the median age of 8.7 (range, 7.4-11.7) years. Kidney transplantation was performed at the median age of 8.8 (range, 1.9-14.7) years in all patients. Overwhelming post-splenectomy infections and cholangitis did not occur during the median follow-up period of 6.3 (range, 1.0-13.2) years. The estimated glomerular filtration rate at the last follow-up was 53 (range, 35-107) mL/min/1.73 m² . No graft loss occurred. Our individualized treatment strategy stratified by recurrent cholangitis and pancytopenia can be a feasible strategy for children with ARPKD who develop ESRD and warrants further evaluation.

Urinary Cross-linked N-terminal Telopeptide of Type I Collagen Levels of Infants with Osteogenesis Imperfecta and Healthy Infants

The urinary cross-linked N-terminal telopeptide of type I collagen (uNTx) levels in infantile osteogenesis imperfecta (OI) have not been well studied. Here we investigated the levels of uNTx in infants with OI and healthy infants. We collected spot urine samples from 30 infants with OI (male/female, 14/16; Sillence classification, I/II/III/IV: 15/3/6/6; age, 5.2±4.4 months) and 120 healthy infants (male/female, 75/45; age, 5.1±4.1 months) for the measurement of uNTx levels. The uNTx levels of the OI infants were significantly lower than those of the healthy infants (mean±SD, 1,363.7±530.1 vs. 2,622.2±1,202.6 nmol BCE/mmol Cr; p＜0.001). The uNTx levels of the infants with type I OI were significantly lower than those of the age-matched healthy infants, although an overlap was observed between the 2 groups. Among the 1-month-old infants, the uNTx levels of the infants with types I, III or IV OI were significantly lower than those of the healthy infants, without overlap (1,622.5±235.8 vs. 3,781.0±1,027.1 nmol BCE/mmol Cr; p＜0.001). These results indicate that uNTx levels are significantly lower in infants with OI than in healthy infants, and they suggest that uNTx might be useful as a reference for diagnosing OI.

New-onset diabetes after renal transplantation in a patient with a novel HNF1B mutation

CAKUT are the most frequent causes of ESRD in children. Mutations in the gene encoding HNF1B, a transcription factor involved in organ development and maintenance, cause a multisystem disorder that includes CAKUT, diabetes, and liver dysfunction. Here, we describe the case of a patient with renal hypodysplasia who developed NODAT presenting with liver dysfunction. The NODAT was initially thought to be steroid and FK related. However, based on the patient's clinical features, including renal hypodysplasia and recurrent elevations of transaminase, screening for an HNF1B mutation was performed. Direct sequencing identified a novel splicing mutation of HNF1B, designated c.344 + 2T>C. Because CAKUT is the leading cause of ESRD in children and HNF1B mutations can cause both renal hypodysplasia and diabetes, HNF1B mutations may account for a portion of the cases of NODAT in pediatric patients who have undergone kidney transplantation. NODAT is a serious and major complication of solid organ transplantation and is associated with reduced graft survival. Therefore, for the appropriate management of kidney transplantation, screening for HNF1B mutations should be considered in pediatric patients with transplants caused by CAKUT who develop NODAT and show extra-renal symptoms.

Functional analysis of NPHS1 mutations in Japanese patients

BACKGROUND

Many mutations in the NPHS1 gene were detected among patients with congenital nephrotic syndrome. Functional analysis of those mutations was done with a stable-expression cell line. Nevertheless, establishing such a cell line is time-consuming.

METHODS AND RESULTS

We established an easier method using automatic counting software for functional analysis with transient-transfection cells rather than a stable-expression cell line. We demonstrated maltrafficking to the plasma membrane of abnormal nephrin for immunostaining on transient-expression cells by comparison without Triton X (detecting proteins on the cell membrane only) and with Triton X (detecting proteins both on the cell membrane and inside the cell cytoplasm). We obtained relevant results with data obtained previously using a stable-expression cell line. Furthermore, we conducted functional analysis of NPHS1 mutations in Japanese patients with congenital nephrotic syndrome using this simple method, which revealed that all pathogenic mutations impaired trafficking to the protein plasma membrane.

CONCLUSIONS

Functional analysis using transient-expression cells with automatic counting software was useful to demonstrate maltrafficking to the plasma membrane of a protein. All pathogenic mutations detected in Japanese patients impaired trafficking to the protein plasma membrane.

Fibroblast growth factor 23 concentrations in healthy term infants during the early postpartum period

Fibroblast growth factor 23 (FGF23) is a potent regulator of Pi and 1,25-(OH)(2)D homeostasis. Early postpartum infants show intriguing changes in serum levels of Ca, Pi, PTH and 1,25-(OH)(2)D. However, the role of FGF23 in the early neonatal mineral metabolism has not been clarified. In order to evaluate the significance of FGF23 during the early postpartum period, we examined the circulating FGF23 levels using an intact FGF23 ELISA and a C-terminal FGF23 ELISA either in 22 umbilical cord blood samples (the cord blood) or in 22 term infants at 5days of life (the 5-day-old infant). We also compared these ranges with those of 11 healthy adults. Data were expressed as mean+/-SD, and analyzed by two-way ANOVA, followed by the Tukey's test. C-terminal FGF23 in the cord blood, the 5-day-old infants and the healthy adults were 73.3+/-22.4, 81.0+/-28.2 and 39.0+/-7.8 RU/ml, respectively. Intact FGF23 in the cord blood, the 5-day-old infants and the healthy adults were 3.9+/-1.6, 21.8+/-17.6, and 27.6+/-7.3 pg/ml, respectively. Immunoprecipitation assays using anti-FGF23 antibodies demonstrated that the intact 32 kDa FGF23 was low and the fragmented FGF23 of 18kDa was abundant in the cord blood compared with those in the healthy adults. In conclusion, our observations indicated that the intact FGF23/C-terminal FGF23 ratio was very low due to the fragmentation of FGF23 during the early postpartum period and might have a considerable contribution to the Pi homeostasis in the healthy term infants.

Fibroblast growth factor 23 concentrations in healthy term infants during the early postpartum period

Fibroblast growth factor 23 (FGF23) is a potent regulator of Pi and 1,25-(OH)(2)D homeostasis. Early postpartum infants show intriguing changes in serum levels of Ca, Pi, PTH and 1,25-(OH)(2)D. However, the role of FGF23 in the early neonatal mineral metabolism has not been clarified. In order to evaluate the significance of FGF23 during the early postpartum period, we examined the circulating FGF23 levels using an intact FGF23 ELISA and a C-terminal FGF23 ELISA either in 22 umbilical cord blood samples (the cord blood) or in 22 term infants at 5 days of life (the 5-day-old infant). We also compared these ranges with those of 11 healthy adults. Data were expressed as mean+/-SD, and analyzed by two-way ANOVA, followed by the Tukey's test. C-terminal FGF23 in the cord blood, the 5-day-old infants and the healthy adults were 73.3+/-22.4, 81.0+/-28.2 and 39.0+/-7.8 RU/ml, respectively. Intact FGF23 in the cord blood, the 5-day-old infants and the healthy adults were 3.9+/-1.6, 21.8+/-17.6, and 27.6+/-7.3 pg/ml, respectively. Immunoprecipitation assays using anti-FGF23 antibodies demonstrated that the intact 32 kDa FGF23 was low and the fragmented FGF23 of 18 kDa was abundant in the cord blood compared with those in the healthy adults. In conclusion, our observations indicated that the intact FGF23/C-terminal FGF23 ratio was very low due to the fragmentation of FGF23 during the early postpartum period and might have a considerable contribution to the Pi homeostasis in the healthy term infants.

A randomised, placebo controlled clinical trial of the aldose reductase inhibitor CT-112 as management of corneal epithelial disorders in diabetic patients

AIM

To evaluate the efficacy of topical aldose reductase inhibitor CT-112 (5-[3-ethoxy-4-pentyloxyphenyl]-2,4-thiazolidinedione) on corneal epithelial barrier function in diabetic patients.

METHODS

This was a prospective, randomised, double masked placebo controlled study. 34 eyes of 34 diabetic patients were randomly assigned treatment with 0.25% eye drops of CT-112 (n = 22) or a placebo (n = 12) four times a day for 8 weeks. Corneal fluorescein staining and corneal sensation were examined before treatment as well as 4 and 8 weeks after administration. Corneal epithelial permeability to fluorescence was measured with an anterior fluorophotometer.

RESULTS

Average scores of superficial punctate keratopathy and corneal sensitivity did not differ significantly between the two groups at any time. Whereas average fluorescein concentrations did not differ significantly for the CT-112 and placebo groups before treatment, they did differ significantly 4 and 8 weeks after treatment (4 weeks, p = 0.0327; 8 weeks, p = 0.0143).

CONCLUSION

The topical aldose reductase inhibitor, CT-112 improves the corneal epithelial barrier function in diabetic patients.

Direct reduction of alcohols: highly chemoselective reducing system for secondary or tertiary alcohols using chlorodiphenylsilane with a catalytic amount of indium trichloride

The direct reduction of alcohols using chlorodiphenylsilane as a hydride source in the presence of a catalytic amount of indium trichloride is described. Benzylic alcohols, secondary alcohols, and tertiary alcohols were effectively reduced to give the corresponding alkanes in high yields. A compound bearing both primary and secondary hydroxyl groups was reduced only at the secondary site to afford the primary alcohol after workup with Bu(4)NF. This system showed high chemoselectivity only for the hydroxyl group while not reducing other functional groups that are readily reduced by standard reducing systems. Thus alcohols bearing ester, chloro, bromo, or nitro groups, which are sensitive to LiAlH(4) or Zn/H(+), were selectively reduced only at the hydroxyl sites by the chlorodiphenylsilane/InCl(3) system. NMR studies revealed the reaction course. The hydrodiphenylsilyl ether is initially formed and then, with InCl(3) acting as a Lewis acid, forms an oxonium complex, which accelerates the desiloxylation with donation of the hydrogen to the carbon.

Motility of single one-headed kinesin molecules along microtubules

The motility of single one-headed kinesin molecules (K351 and K340), which were truncated fragments of Drosophila two-headed kinesin, has been tested using total internal reflection fluorescence microscopy. One-headed kinesin fragments moved continuously along the microtubules. The maximum distance traveled until the fragments dissociated from the microtubules for both K351 and K340 was approximately 600 nm. This value is considerably larger than the space resolution of the measurement system (SD approximately 30 nm). Although the movements of the fragments fluctuated in forward and backward directions, statistical analysis showed that the average movements for both K340 and K351 were toward the plus end of the microtubules, i.e., forward direction. When BDTC (a 1.3-S subunit of Propionibacterium shermanii transcarboxylase, which binds weakly to a microtubule), was fused to the tail (C-terminus) of K351, its movement was enhanced, smooth, and unidirectional, similar to that of the two-headed kinesin fragment, K411. However, the travel distance and velocity of K351BDTC molecules were approximately 3-fold smaller than that of K411. These observations suggest that a single kinesin head has basal motility, but coordination between the two heads is necessary for stabilizing the basal motility for the normal level of kinesin processivity.

Antiseptic effects at injection sites

To our knowledge, there are no published papers detailing antisepsis for injection sites. In view of this, the efficacies of povidone-iodine (PVP-I) ethanol solution and chlorhexidine (CH) ethanol, the agents most commonly used for antisepsis of the operative field, were compared. Before and after the injection site was disinfected with either of these antiseptics, specimens of indigenous bacteria on the skin were collected by the cylinder scrub method, and the bacteria reduction rate and the reduction factor (RF) were determined to evaluate the efficacy of antisepsis. The bacteria reduction rate and RF value obtained for PVP-I ethanol were 95.1 +/- 11.2 and 2.1 +/- 0.9% and those for CH ethanol were 93.5 +/- 9.3 and 1.8 +/- 0.9%. Since there were individual differences in cell count before antisepsis, no significant difference was seen in bactericidal activity. However, slightly more favorable results were obtained with PVP-I ethanol. Although it is impossible to eradicate completely the indigenous microbes with currently available methods, it is considered important for the prevention of infection of the injection site to decrease bacterial counts as much as possible.

Interleukin-6 overexpression cannot generate serious disorders in severe combined immunodeficiency mice

C57BL/6 human interleukin-6 (IL-6) transgenic mice develop mesangial proliferative glomerulonephritis with massive IgG1 plasmacytosis and die of renal failure in early life. To test whether the IL-6 overexpression could cause development of mesangial proliferative glomerulonephritis without plasmacytosis or promote proliferation of immature B cells that have not undergone immunoglobulin gene rearrangement, the IL-6 transgene was introduced into mice with severe combined immunodeficiency (SCID). In the immunocompetent littermate IL-6 transgenic mice, there were various symptoms such as plasmacytosis, nephropathy, anemia, and thrombocytosis, accompanied by marked increases in serum IL-6 levels as they aged. All these mice died by 25 weeks of age. In contrast, the SCID-IL-6 transgenic mice had no such abnormalities, except certain hematological changes, although the transgene was expressed in various tissues. In these mice, the serum IL-6 levels were 10- to 15-fold higher than those in the nontransgenic mice, and they remained constant throughout their lives. Furthermore, there were no signs of lymphoid development. This study demonstrates that deregulation of IL-6 expression does not stimulate cell growth or differentiation of immature B cells, and thus does not result in plasmacytosis and age-related increases in IL-6 production, and also does not generate mesangial proliferative glomerulonephritis.

Induction of autoimmune disease by graft-versus-host reaction across MHC class II difference: modification of the lesions in IL-6 transgenic mice

We examined the effect of IL-6 on the development of autoimmune diseases (primary biliary cirrhosis, Sjögren's syndrome) employing murine graft-versus-host reaction (GVHR) model with MHC class II disparity. For this purpose, we used IL-6 transgenic (B6.6) mice in which a high level of IL-6 was detected. C57Bl/6 (B6) spleen T cells were injected into B6.6 mated with B6.C-H-2bm12 (bm12) mutant mice ((bm12 x B6.6)F1) and GVHR with MHC class II disparity was induced. The transgenic hybrid mice with GVHR showed a larger spleen index and contained a higher serum level of IL-6 than those without GVHR. Autoimmune-like lesions in transgenic recipients became weakened compared with those in non-transgenic (bm12 x B6)F1 recipients. In contrast, levels of antimitochondrial antibodies in (bm12 x B6.6)F1 GVHR group were significantly higher than that of (bm12 x B6)F1 GVHR group. These results indicate that IL-6 excessively produced in vivo might regulate the progression of autoimmune diseases.

Changes in the concentrations of urinary proteins after physical exercise

The influence of physical exercise on the urinary excretion of proteins was examined in 17 male high school baseball players. Their urine was collected before and after exercise to determine the concentrations of total protein, albumin, beta 2-microglobulin and creatinine along with the activity of N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30). Concentrations of total protein, albumin, beta 2-microglobulin and creatinine increased significantly (p less than 0.01) after exercise, while N-acetyl-beta-D-glucosaminidase activity did not increase. Similar results were obtained when the concentrations of these urinary components were calculated on the basis of a urinary density of 1.024, and when they were expressed relative to the amount of creatinine. Positive correlations were seen among total protein, albumin, beta 2-microglobulin and creatinine concentrations, but not between the beta 2-microglobulin concentration and N-acetyl-beta-D-glucosaminidase activity. Isoenzyme activities of N-acetyl-beta-D-glucosaminidase in the urine were determined by electrophoresis on cellulose acetate plates. After exercise, the A-form increased slightly, and the B-form decreased slightly, but these changes were not statistically significant.

[Establishment of a new hereditary-cataract mouse (CSM) strain derived from SENCAR mouse]

A mouse representing a new hereditary cataract strain was found in a mouse colony and a new line was established strain CSM. These mice were investigated genetically, histologically and biochemically. The results suggested that this cataract was apparently inherited through two recessive autosomal genes. Histologically the denucleation process of lens fibers was abnormal and small vacuoles appeared in the equatorial region of the lens cortex at 12 days. Biochemically, insoluble protein and sodium increased in the lens with age.

Immunologic abnormality in NZB/NZW F1 mice. Thymus-independent occurrence of B cell abnormality and requirement for T cells in the development of autoimmune disease, as evidenced by an analysis of the athymic nude individuals

Both NZB nu/+ and NZW nu/+ mice were microbially clean by cesarean section. The (NZB x NZW)F1 hybrid (NZB/W) nu/nu mice and nu/+ littermates were then generated by mating of NZB nu/+ with NZW nu/+mice under specific pathogen-free conditions. The female NZB/W F1 nu/nu mice did not develop autoimmune kidney disease, whereas all of nu/+ female littermates mice exhibited proteinuria and died of renal failure with a 50% survival time of 35 wk. Namely, nude mice had no signs of proteinuria up to the time of their death caused by other diseases rather than glomerulonephritis, and their mean survival time was greater than 45 wk. Nude mice had also no anti-ssDNA antibody in their serum. However, splenic B cells of NZB/W nude mice exhibited hyper-responsiveness to both LPS and B151-TRF2, a T cell-derived polyclonal B cell-stimulation factor, and produced large numbers of Ig-secreting cells and anti-TNP plaque-forming cells as well as anti-ssDNA antibody comparable to the nu/+ littermate mice. Interestingly, thymus-engrafted NZB/W nude mice developed autoimmune disease exemplified by the induction of anti-ssDNA antibody and proteinuria at approximately the same time as their nu/+ littermates. These results indicate that the B cell hyper-responsiveness found in NZB/W mice is apparently determined by the T cell-independent process, and T cells are obligatorily required for the development of autoimmune disease in NZB/W mice.

[The development of newborn C 57 BL/KsJ-dbm mice produced from eggs fertilized in vitro]

The purpose of this study was to examine the development of newly born C57BL/KsJ-dbm mice produced from eggs fertilized in vitro. The embryos derived from fertilization in vitro (which was performed by using db/db eggs and adrenalectomized db/db (Adrex) spermatozoa,) were transferred to the oviduct of MRL/MpJ pseudopregnant recipients 30 hr after insemination. 376 of these embryos yielded 65 young. Weight gain and urine glucose, plasma glucose and insulin levels were measured in these young as well as in Adrex males. The young produced by fertilization in vitro showed hyperglycemia, hyperinsulinemia and obesity. The physiological abnormalities in these young were similar to those in db/db young produced by natural mating between heterozygote (db/+) males and females. Adrex males did not show hyperglycemia but did show hyperinsulinemia. These results indicate that in vitro fertilization and embryo transfer is an effective means of producing fetuses or newborns with an overt genotype in genetically diabetic obese (db) mice.

Immunologic abnormality in NZB/NZW F1 mice. Thymus-independent occurrence of B cell abnormality and requirement for T cells in the development of autoimmune disease, as evidenced by an analysis of the athymic nude individuals

Both NZB nu/+ and NZW nu/+ mice were microbially clean by cesarean section. The (NZB x NZW)F1 hybrid (NZB/W) nu/nu mice and nu/+ littermates were then generated by mating of NZB nu/+ with NZW nu/+mice under specific pathogen-free conditions. The female NZB/W F1 nu/nu mice did not develop autoimmune kidney disease, whereas all of nu/+ female littermates mice exhibited proteinuria and died of renal failure with a 50% survival time of 35 wk. Namely, nude mice had no signs of proteinuria up to the time of their death caused by other diseases rather than glomerulonephritis, and their mean survival time was greater than 45 wk. Nude mice had also no anti-ssDNA antibody in their serum. However, splenic B cells of NZB/W nude mice exhibited hyper-responsiveness to both LPS and B151-TRF2, a T cell-derived polyclonal B cell-stimulation factor, and produced large numbers of Ig-secreting cells and anti-TNP plaque-forming cells as well as anti-ssDNA antibody comparable to the nu/+ littermate mice. Interestingly, thymus-engrafted NZB/W nude mice developed autoimmune disease exemplified by the induction of anti-ssDNA antibody and proteinuria at approximately the same time as their nu/+ littermates. These results indicate that the B cell hyper-responsiveness found in NZB/W mice is apparently determined by the T cell-independent process, and T cells are obligatorily required for the development of autoimmune disease in NZB/W mice.

Selective urinary excretion of phosphatidyl ethanolamine in patients with chronic glomerular diseases

Urinary phospholipids and lipoproteins in chronic glomerular diseases were analyzed. The subjects used were 26 patients consisting of 14 with chronic glomerulonephritis and 12 with nephrotic syndrome. Nine healthy normals served as controls. Phospholipids were isolated by one-dimensional thin-layer chromatography (TLC) using an internal standard for quantification and partially by two-dimensional TLC and, furthermore, quantified by two different methods to ascertain the kinds of phospholipids. Urinary lipoproteins were isolated by density gradient ultracentrifugation and analyzed by electrophoresis. The urinary excretion of phosphatidyl ethanolamine (PE) was recognized exclusively in the patient group and that of phosphatidyl serine (PS) in most cases with nephrotic syndrome. The daily urinary PE excretion rate was closely correlated to the urinary albumin excretion rate. However, phosphatidyl choline (PC) and sphingomyelin (SPH), which are main phospholipids in serum and red blood cell membranes, in most cases were hardly detected in urine. These observations were confirmed by two-dimensional TLC using valuable spot tests for identification of phospholipids and also by the two different quantification methods. In density gradient ultracentrifugation, urinary lipoproteins did not form such peaks as seen in the profiles of serum lipoproteins. The presence of urinary lipoproteins in two nephrotic patients has been shown, but although the method used was not very sensitive, it was suggested that lipoproteins were hardly excreted into urine as the lipoprotein deficient fraction (LPDF) (d greater than 1.21 g/ml), in which albumin is predominant. PE was found mainly in LPDF of urine, although the amount of PE in urinary lipoproteins was very limited.(ABSTRACT TRUNCATED AT 250 WORDS)