Mechanisms of ischaemic neural progenitor proliferation: a regulatory role of the HIF-1α-CBX7 pathway.

AIMS: Investigations of the molecular mechanisms of hypoxia- and ischaemia-induced endogenous neural progenitor cell (NPC) proliferation have mainly focused on factors secreted in response to environmental cues. However, little is known about the intrinsic regulatory machinery underlying the self-renewing division of NPCs in the brain after stroke. METHODS AND RESULTS: Polycomb repressor complex 1-chromobox7 (CBX7) has emerged as a key regulator in several cellular processes including stem cell self-renewal and cancer cell proliferation. The hypoxic environment triggering NPC self-renewal after CBX7 activation remains unknown. In this study, we found that the upregulation of CBX7 during hypoxia and ischaemia appeared to be from hypoxia-inducible factor-1α (HIF-1α) activation. During hypoxia, the HIF-1α-CBX7 cascade modulated NPC proliferation in vitro. NPC numbers significantly decreased in CBX7 knockout mice generated using CRISPR/Cas9 genome editing. CONCLUSIONS: We provided the novel insight that CBX7 expression is regulated through HIF-1α activation, which plays an intrinsically modulating role in NPC proliferation.

Effects of exercise training on cardiac apoptosis in obese rats.

BACKGROUND AND AIM: The purpose of this study was to evaluate the effects of exercise training on cardiac apoptotic pathways in obesity. METHODS AND RESULTS: Sixteen lean Zucker rats (LZR) and sixteen obese Zucker rats (OZR) of 5-6 months of age as well as the other sixteen obese rats were subjected to treadmill running exercise for 1 h everyday for 3 months (OZR-EX). After exercise training or sedentary status of the rats, the excised hearts from the three groups were measured by heart weight index, H&E staining, TUNEL assays and Western blotting. Cardiac TUNEL-positive apoptotic cells, the protein levels of TNF alpha, Fas ligand, Fas receptors, Fas-associated death domain (FADD), Bad, Bax, activated caspase 8, activated caspase 9, and activated caspase 3 were higher in OZR than those in LZR. The protein levels of TNF alpha, Fas ligand, Fas receptors, FADD, activated caspase 8, and activated caspase 3 (Fas pathway) and the protein levels of Bad, Bax, Bax-to-Bcl2 ratio, activated caspase 9, and activated caspase 3 (mitochondria pathway) were lower in OZR-EX than those in OZR. CONCLUSION: Cardiac Fas-dependent and mitochondria-dependent apoptotic pathways become more activated in obesity. Exercise training can prevent obesity-activated cardiac Fas-dependent and mitochondria-dependent apoptotic pathways. Our findings demonstrate a new therapeutic effect of exercise training to prevent delirious cardiac Fas-mediated and mitochondria-mediated apoptosis in obesity.

Lack of pharmacokinetic interaction between dapagliflozin, a novel sodium-glucose transporter 2 inhibitor, and metformin, pioglitazone, glimepiride or sitagliptin in healthy subjects.

AIMS: Dapagliflozin increases urinary glucose excretion by selectively inhibiting renal sodium-glucose transporter 2, an insulin-independent mechanism of action that may be complementary to that of other oral antidiabetes drugs. The current studies assessed the potential for pharmacokinetic (PK) interaction between dapagliflozin and pioglitazone, metformin, glimepiride or sitagliptin in healthy subjects following single-dose administration. METHODS: In open-label, randomized, three-period, three-treatment crossover studies, 24 subjects received 50 mg dapagliflozin, 45 mg pioglitazone or the combination, while 18 subjects received 20 mg dapagliflozin, 1000 mg metformin or the combination. In an open-label, randomized, five-period, five-treatment, unbalanced crossover study, 18 subjects first received 20 mg dapagliflozin, 4 mg glimepiride or the combination, and afterward 100 mg sitagliptin or sitagliptin plus 20 mg dapagliflozin. Blood samples were taken over 72 h of each treatment period. Lack of PK interaction was defined as the ratio of geometric means and 90% confidence interval (CI) for combination:monotherapy being within the range of 0.80-1.25. RESULTS: Co-administration of dapagliflozin with pioglitazone, metformin, glimepiride or sitagliptin had no effect on dapagliflozin maximum plasma concentration (C(max) ) or area under the plasma concentration-time curve (AUC). Similarly, dapagliflozin did not affect the C(max) or AUC for the co-administered drug, except for slight extensions of the 90% CI for the ratio of geometric means for glimepiride AUC (upper limit 1.29) and pioglitazone C(max) (lower limit 0.75). All monotherapies and combination therapies were well tolerated. CONCLUSION: Dapagliflozin can be co-administered with pioglitazone, metformin, glimepiride or sitagliptin without dose adjustment of either drug.

The application of stem cells in the treatment of ischemic diseases.

Ischemia causes oxygen deprivation, cell injury and related organ dysfunction. Although ischemic injury may be local, it involves many biochemical changes in different cell types. The ability of stem cells to differentiate into different cell lineages provides the possibility of their use in treating a variety of diseases requiring tissue repair or reconstitution, such as stroke, ischemic retinopathy, myocardial infarction, ischemic disorders of the liver, ischemic renal failure, and ischemic limb dysfunction. Several cell types including embryonic stem cells, various progenitor and stem cells of hematopoietic or mesenchymal origin have been used in attempts to reconstitute injured tissue. Xenologous or autologous stem cells may be administered either through the peripheral vascular system or directly by regional injection. The stem cells are then guided to the infarct site by homing signals. Either by cell differentiation or paracrine effects, stem cells or progenitor cells participate in the reconstruction of a favorable microenvironment resulting in neovascularization and tissue regeneration that eventually improve the physiological function of organs with ischemic damage.

Stem cell therapy in stroke: strategies in basic study and clinical application.

Stem cell therapies are an important strategy for the treatment of stroke. Bone marrow-derived stem cells (BMSCs) may promote structural and functional repair in several organs via stem cell plasticity. The tissue damage could stimulate the stem cells migration, and they track into the site of damage and then undergo differentiation. The plasticity functions of BMSCs in an injuries tissue are dependent on the specific signals present in the local environment of the damaged tissue. Recent studies have also identified the specific molecular signals, such as SDF-1/CXCR4, required for the interaction of BMSCs and damaged host tissues. This review summarizes the current understanding of how BMSCs reach and function in cerebral ischemic tissues.

Hypoglycemia enhances the expression of prion protein and heat-shock protein 70 in a mouse neuroblastoma cell line.

Cellular prion protein (PrP(C)) expression can be regulated by heat-shock stress, and we designed the present study to determine whether hypoglycemia could affect PrP(C) expression. RT-PCR and Western blotting were used to measure the expression of PrP(C) and heat-shock protein (Hsp70) in mouse neuroblastoma (N18) cells cultured 3 hr to 3 days in media deprived of 97.5% (L) or 75% (M) of its glucose. Hypoglycemia caused a concomitant time-dependent and glucose dose-dependent increase in PrP(C) and Hsp70. In addition, hypoglycemia also increased phosphorylated c-Jun N-terminal kinase (JNK) protein levels in a time-dependent manner. The upregulation of PrP(C) and Hsp70 under hypoglycemic conditions was disrupted by the specific JNK inhibitor SP600125. It was also found from in vitro studies that hypoglycemic conditions induced higher levels of PrP(C) promoter activity in PrP(C) promoters containing a heat-shock element (HSE) than in PrP(C) promoters lacking HSE. We propose that hypoglycemia-increased PrP(C) expression might be due to JNK phosphorylation of a heat-shock transcriptional factor, which then interacts with HSE in the promoter of PrP(C).

The use of radiolabeled compounds for ADME studies in discovery and exploratory development.

Radiolabeled compounds are excellent investigative tools and widely used to carry out ADME studies during drug discovery and development stages. The most commonly used radioisotopes are 14C and 3H. 3H materials are generally easier to synthesize than 14C materials. Therefore, a variety of probes and substrates used in in vitro assays are labeled with 3H. Since synthesis of 14C material requires intensive resources, it is usually not available until after a molecule is considered for potential development or after the molecule enters the development phase. Improvement in the technology in radiochemistry has enabled the use of radiolabeled compounds earlier in pre-clinical and clinical development to address mechanistic issues. For in vitro studies, radiolabeled probes are utilized to test affinity with various transporters, to perform metabolism comparison among species and to assess possible formation of reactive metabolites. For in vivo studies, radiolabeled compounds are employed to identify and elucidate metabolites formed, to investigate the extent of absorption, bioavailability, tissue distribution, mass balance, routes of excretion, and pre-systemic metabolism. Due to the significant impact of radiolabeled studies on drug development, these studies will be performed earlier than have been in the past and will continue to be an integral part of drug discovery and development.

A pharmacokinetic interaction study between butorphanol and sumatriptan nasal sprays in healthy subjects: importance of the timing of butorphanol administration.

Sumatriptan and butorphanol nasal sprays are commonly used agents for the management of migraine headaches. Under certain circumstances, these two agents may be administered closely in time. However, the possibility of a pharmacokinetic interaction and the safety of this regime have not been examined. In this crossover design study, 24 healthy subjects received the following four treatments, each separated by at least 7 days: 1 mg butorphanol (Stadol NS7); 20 mg sumatriptan (Imitrex Nasal Spray); or both formulations together with butorphanol administered either 1 or 30 min after sumatriptan. Serial plasma samples were collected for 24 h post-dose and analysed for butorphanol and/or sumatriptan by HPLC-MS/MS. Butorphanol plasma concentrations were reduced when it was administered 1 min (mean 28.6% decrease in AUC(0-infinity)), but not 30 min, after sumatriptan. The pharmacokinetics of sumatriptan were not substantially altered by butorphanol. The combination of nasally administered sumatriptan and butorphanol appeared safe. However, if butorphanol nasal spray is administered <30 min after sumatriptan nasal spray, the analgesic effect of butorphanol may be diminished due to reduced nasal absorption resulting from probable transient vasoconstriction of nasal blood vessels by sumatriptan.

Factors determining the attitudes of family caregivers of dementia patients toward nursing home placement in Taiwan: comparisons between urban and semiurban areas.

This study sought to determine the factors that influence the attitudes of family caregivers of dementia patients toward nursing home placement. A telephone survey of primary caregivers was conducted in two metropolitan areas of Taiwan. Caregivers of dementia patients were recruited from the neurology and psychiatry outpatient departments of two medical centers in Taipei (a highly urbanized area, n=144) and two medical centers in Kaohsiung (an area of mixed farm and nonfarm sectors, n=134). Family caregivers were asked if they would place patients in a nursing home if their dementia progressed. The mental status of dementia patients was the most significant variable affecting caregivers attitudes toward nursing home placement. Family manpower available for caregiving at home was especially emphasized as a determining factor affecting the decision to use nursing home care by primary caregivers in highly urbanized areas.

Genome-wide hypomethylation in hepatocellular carcinogenesis.

Aberrant genome-wide hypomethylation has been thought to be related to tumorigenesis. However, its mechanism and implications in hepatocellular carcinogenesis remain to be elucidated. Samples of hepatoma (hepatocellular carcinoma, HCC) and paired non-HCC liver tissues were obtained from 17 HCC patients. Normal liver tissues obtained from three individuals were used as controls. Compared with the paired non-HCC liver tissues, genome-wide 5-methylcytosine content in HCC was reduced in all of the tested HCC samples (P < 0.001). Conversely, genome-wide 5-methylcytosine content did not significantly differ among normal, noncirrhotic, and cirrhotic liver tissues. Moreover, the degree of reduced DNA methylation was related to late histopathological HCC grade (P = 0.005) and large tumor size (P = 0.079). Compared with the paired non-HCC liver tissues, expression of DNA methyltransferases DNMT-1, DNMT-3A, and DNMT-3B and the DNA methyltransferase-like gene, DNMT-2, was up-regulated in 53, 41, 59, and 47% of the HCC samples, respectively. Surprisingly, small amounts of LINE-1 retrotransposon transcripts were detected in HCC and non-HCC as well as normal liver tissues, and the expression levels were not significantly different in HCC compared with the paired non-HCC or normal liver tissues. Of interest, the 3' ends of these LINE-1 transcripts were truncated. Our findings suggest that genome-wide hypomethylation in HCC is a continuing process that persists throughout the lifetime of the tumor cells rather than a historical event occurring in precancer stages or in cell origins for HCC. Up-regulation of DNA methyltransferases might simply be a result of increased cell proliferation in cancer. In addition, our results did not support the hypothesis of activation of transposable elements in HCC via genome-wide hypomethylation.

Comparisons of the cost-effectiveness among hospital chronic care, nursing home placement, home nursing care and family care for severe stroke patients.

AIM: This study compared the cost and effectiveness of long-term institutional care and home care for stroke patients with severe physical disabilities. BACKGROUND: Whether home care is more economical or effective than institutional care for patients with chronic illnesses remains controversial when the cost of family labour is considered. Thus, decisions concerning the appropriate type of care setting for patients with severe chronic illness remain difficult. METHODS: From November 1995 to March 1996, 313 hospitalized stroke patients with severe physical disabilities treated at one of five hospitals in the Taipei metropolitan area were followed from the day of hospital discharge until the third month after discharge. These 313 patients were divided into four groups as follows: (1) 106 who were admitted to a chronic care unit in a hospital, (2) 60 who were admitted to nursing homes, (3) 60 who received professional home nursing care and (4) 87 who returned home without receiving professional care. The change of physical functional status in the patient was examined as the difference between activities of daily living (ADL) scores measured at discharge and at the end of the third month after discharge. RESULTS: Information on family costs for caregiving, including pay for long-term services utilized, labour costs for caregiving and out-of-pocket expenditures for miscellaneous materials was obtained during a weekly telephone interview. The results indicated that caring for patients in their own homes was not only more expensive but was also less effective in improving ADL scores than caring for patients in nursing homes and in chronic care units of hospitals. CONCLUSIONS: The results suggest that caring for patients with severe physical disabilities in institutions is more appropriate than caring of them at home.

Estimation of the family cost of private nursing home care versus home care for patients with dementia in Taiwan.

BACKGROUND: Although overall estimates of the cost of dementia in Taiwan have been published, the relative cost of home care versus nursing home care for these patients is unclear. This study estimated the costs of home care and nursing home care for families of patients with either Alzheimer's disease or vascular dementia in Taiwan. METHODS: Data from previous reports were used to estimate costs of home care and nursing home care for families of patients with dementia, as well as the prevalence of dementia in Taiwan. RESULTS: The cost of home care per patient per month was NT$85,256 for patients with Alzheimer's disease and NT$74,152 for patients with vascular dementia. Labor was the predominant factor (96%) in home care. When the cost of labor was deducted from the calculation, the family cost per patient per month was reduced to NT$4,059 for Alzheimer's disease and NT$2,956 for vascular dementia. For patients receiving nursing home care, costs per month per patient were estimated to be NT$28,972 for patients with Alzheimer's disease and NT$31,576 for those with vascular dementia. Nursing home fees were the major component of costs incurred by families (at least 78% of total family costs). For both Alzheimer's disease and vascular dementia, payment for nursing home services amounted to approximately one-third of the labor costs of home care. CONCLUSIONS: These results indicate that nursing home placement for dementia patients provides a labor cost-savings for families in Taiwan.

Cost analyses of home care and nursing home services in the southern Taiwan area.

This study compares the cost of long-term care provided at patient homes with that of long-term care provided in nursing homes in southern Taiwan. Caring for a patient with a high degree of dependence at home is more expensive than caring for a patient in a nursing home facility when family costs and provider costs are considered together. This phenomenon is not demonstrated for patients with medium degrees of dependence. To be cost-effective, home care services should target patients with medium physical disability, and nursing home care should focus on patients with high levels of dependence.

Heat shock modulates prion protein expression in human NT-2 cells.

The pathological hallmarks of Prion disease are cortical spongiform changes and neuronal loss, which are induced by the accumulation of the scrapie-isoform prion protein (PrP(Sc)). PrP(Sc) is derived from a post-translational modification of the cellular form of prion protein (PrP(C)). Heat-shock proteins, a group of molecular chaperones, are involved in the degradation of denatured proteins and post-translational folding of newly synthesized polypeptides. In an attempt to examine any possible relationship between heat shock stress and an induction of prion protein (PrP), human NT-2 cells were treated with heat shock at 42 degrees C for 30 min. After heat-shock treatment, both the level of mRNA and PrP(C) protein were analyzed at various time points by Northern and Western blot, respectively. There was a 1.5- to 2.5-fold increase in PrP mRNA levels 1 and 3h following heat shock. In addition, a two-fold increase in protein level of PrP was found 3 h after heat-shock treatment. These results suggest that cellular stress induces the elevation of both PrP mRNA and protein synthesis. The up-regulation of prion-protein mRNA and protein, implies that PrP may play a role in cellular stress.

Creutzfeldt-Jakob disease: heat shock protein 70 mRNA levels in mononuclear blood cells and clinical study.

Prion diseases such as Creutzfeldt-Jakob disease (CJD) are associated in most cases with the accumulation of an unusual isoform of prion protein (PrPSC). PrPSC is derived from the abnormal folding of the cellular isoform of prion protein (PrPC). On the other hand, heat shock protein is known to ensure proper protein assembly and folding and to facilitate proteolytic digestion of abnormal or denatured proteins. Many studies have therefore hypothesized that heat shock protein is linked to prion disease. We examined the relationship between heat shock protein HSP70 and prion disease in CJD patients. HSP70 mRNA levels in mononuclear blood cells (MBCs) were compared in 14 CJD patients (10 confirmed by histo-pathological study), 12 vascular dementia (VD) patients, 16 patients with Parkinson's disease and dementia (PD) and 14 nondemented control subjects. The possible correlation between HSP70 mRNA expression levels and clinical findings was also evaluated. HSP70 mRNA expression levels in MBCs were measured by northern blotting. HSP70 mRNA levels in MBCs from patients with CJD were significantly higher than those from patients with VD or PD and in nondemented controls. Age at symptom onset, dementia severity, disease duration and neuroimaging grade of CJD patients were not correlated with relative HSP70 mRNA levels. No significant relationship between HSP70 mRNA levels and ageing was found. These results suggest that measurement of HSP70 mRNA in MBCs might provide an auxiliary tool for the diagnosis of CJD.

Sensitive triple-quadrupole mass spectrometric assay for the determination of BMS-181885, a 5-HT1 agonist, in human plasma following solid phase extraction.

A sensitive, selective, accurate, precise and reproducible triple-quadrupole liquid chromatographic-mass spectrometric assay was developed and validated for BMS-181885 (I), a 5HT1 agonist, in human plasma using BMS-181101 as the internal standard (IS). The method involved solid phase extraction of plasma containing I and the IS using Isoelute CN cartridges. The supernatant was then evaporated to dryness at 40 degrees C. The residue was dissolved in 100 microL of the injecting solvent. The HPLC column was ODS-3, 2 x 100 mm. The mobile phase comprised 10 mM ammonium formate (pH = 4) and acetonitrile, 55:45 v/v, used in an isocratic condition. The mass spectrometer was programmed to admit the protonated molecules at m/z 461 (I) and m/z 370 (IS) via the first quadrupole filter and to select reaction monitoring of ions at m/z 152 for I and IS for the quantification. Standard curves were fitted to a weighted quadratic function over the concentration range 0.2-200 ng/mL. The lowest standard concentration (0.2 ng/mL) was experimentally established as the lower limit of quantitation of the assay. The mean predicted quality control concentrations deviated within +/- 11% of the corresponding nominal values; the intra-assay and inter-assay precisions were within 7.0% relative standard deviation. I was stable in the injection solvent at 4 degrees C for at least 24 h and for at least three freeze-thaw cycles. Freezer stability of I in plasma was demonstrated for at least 3 months. The extraction recovery of I was established as 97%. The validated assay was applied to a pharmacokinetic study of I in humans.

Estimation of costs due to hospitalization for first-ever stroke patients in northern Taiwan.

BACKGROUND: The need for healthcare services and the related costs for stroke patients may rise steadily in the future. Even with the predictable and substantial burden of stroke, little effort has been devoted to measuring the population-based direct medical and nonmedical costs in Taiwan. METHODS: Data from the study "Epidemiological Study of Stroke, Diabetes, and Cardiovascular Disease," which included 8,705 people older than 35 years of age, and the study "Costs of Stroke," which included 660 first-ever stroke patients, were used for the cost calculations. The cost of hospital care for stroke patients was obtained in two steps. First, the incidence of stroke and readmissions within one year were tallied; the sum was then multiplied by the average length of stay. Second, the total medical and nonmedical costs were divided by the sum obtained from step 1. The resulting quotient obtained was the cost of hospital care for stroke patients per day. RESULTS: There were 6,691 incidents of stroke and stroke-related readmissions in 1995 (4,041 men and 2,650 women). The total person-days of hospital stay were 233,569 days (144,264 for men and 89,305 days for women). The average medical and nonmedical costs of hospital care per person-day was US $251.4 (NT $6,788 at an exchange rate of US $1 = NT $27). Cost for men (US $287, NT $7,749) was more than for women (US $208, NT $5,616). The total direct costs of hospital care were US $58,710,000 (NT $1,585,000,000) in 1995. CONCLUSIONS: An average of US $1,682,000 (NT $45,410,000) in hospital care costs for stroke could have been saved in 1995 if the person-day stay had been decreased by only one day.

The willingness of families caring for victims of stroke to pay for in-home respite care--results of a pilot study in Taiwan.

This contingent survey was designed to investigate the willingness of family caregivers of stroke victims to pay for in-home respite care. Between September 1996 and December 1996, a designated family member from each family of 174 vascular accident patients hospitalized in the Taipei Metropolitan Area, including two medical centers, received the first interview during preparation and planning for discharge of the patient from the hospital, and follow up interview in their own homes at the end of the second month after the patient was discharged from the hospital. A willingness to pay for in-home respite care was measured as the percentage of monthly family income which would be sacrificed to receive the respite care. Logistic regressions were used to perform multivariate analysis. The willingness to pay for respite care ranged from US$ 363 to 2182, and 42.5% of the family caregivers interviewed indicated a willingness to pay at least 50% of monthly family income for respite care. Family income was strongly associated with the amount of money that family caregivers were willing to pay for respite care. After results were adjusted for the effect of variance in income level, the degree of dependence of patients on the caregiver was significantly associated with the percentage of monthly family income for respite care. The more severe the physical dysfunction of patient, the higher the willingness to pay for in-home respite care utilization. Initially, respite care could be provided to families caring for patients with severe dysfunction, and then the scope enlarged to include caregivers taking care of patients with mild dysfunction.

Cost comparisons between family-based care and nursing home care for dementia.

A prospective study was carried out in Taiwan to measure the family cost of caregiving at home for 289 patients newly diagnosed with dementia (106 with senile-type dementia, 171 with vascular-type dementia). Their families were first interviewed in the outpatient department and then followed for 1 month after the dementia diagnosis was made. Simultaneously, the costs for providing nursing home care to patients with dementia were calculated using accounting data reported from six nursing homes. Comparisons were made between the amount and type of cost encountered by families and by nursing homes to determine whether family-based care was cheaper and more appropriate than nursing home care for dementia patients with different functional levels. The results showed that higher costs were encountered for caregiving at home when the patients had severe dependence. This tendency was more evident for patients with senile dementia than for patients with vascular-type dementia. The cost of labour was an important expense for families caring for patients at home (at least 85% of family costs). Our findings suggest that, when family labour cost is considered, nursing home care is less expensive than family-based care for long-term care, especially for dementia patients with severe or moderate dependence. Nursing home care is also a better choice when patients have great need for multiple health services.

Single dose and multiple dose pharmacokinetics of 2'-fluoro-2',3'-dideoxyadenosine and 2'-fluoro-2',3'-dideoxyinosine, anti-HIV agents, in rats.

A single and multiple dose pharmacokinetic (PK) study was conducted in rats following oral administration of 2'-fluoro-2',3'-dideoxyadenosine (FddA) and 2'-fluoro-2',3'-dideoxyinosine (FddI) at three dose levels. Six rats/gender were assigned to one of the three FddA or FddI dose levels: 40, 250, and 1000 mg/kg/day. Three rats/gender were assigned to the PK study on day 1, while the remaining 3 rats/gender were assigned to the PK study on day 14. The rats received the appropriate doses of either FddA or FddI orally by gavage once a day for 14 days. Serial blood samples up to 24 h and cumulative urine samples (0-24 h) were collected on both days 1 and 14. Plasma and urine samples were analyzed for the concentrations of intact FddA and/or FddI using a validated assay. The data were subjected to non-compartmental PK analyses. Over the dose range of 40-1000 mg/kg. both FddA and FddI exhibited dose dependent pharmacokinetics in rats. Following FddA administration, there was a rapid and extensive in vivo conversion of FddA to FddI; FddI was the major circulating moiety as reflected by Cmax and AUC values (generally 2-3-fold greater than those of FddA at each dose level) as well as the amount excreted (%UR) in the urine. In contrast, following FddI administration, Cmax, AUC, and %UR values were 2-5-fold lower as compared to the FddI generated from FddA administration at each dose level, which also suggested that FddI was not absorbed as extensively as FddA. Based on the findings of this study, FddA is an excellent prodrug of FddI.