Biological Distribution after Oral Administration of Radioiodine-Labeled Acetaminophen to Estimate Gastrointestinal Absorption Function via OATPs, OATs, and/or MRPs

We evaluated the whole-body distribution of orally-administered radioiodine-125 labeled acetaminophen (¹²⁵I-AP) to estimate gastrointestinal absorption of anionic drugs. ¹²⁵I-AP was added to human embryonic kidney (HEK)293 and Flp293 cells expressing human organic anion transporting polypeptide (OATP)1B1/3, OATP2B1, organic anion transporter (OAT)1/2/3, or carnitine/organic cation transporter (OCTN)2, with and without bromosulfalein (OATP and multidrug resistance-associated protein (MRP) inhibitor) and probenecid (OAT and MRP inhibitor). The biological distribution in mice was determined by oral administration of ¹²⁵I-AP with and without bromosulfalein and by intravenous administration of ¹²⁵I-AP. The uptake of ¹²⁵I-AP was significantly higher in HEK293/OATP1B1, OATP1B3, OATP2B1, OAT1, and OAT2 cells than that in mock cells. Bromosulfalein and probenecid inhibited OATP- and OAT-mediated uptake, respectively. Moreover, ¹²⁵I-AP was easily excreted in the urine when administered intravenously. The accumulation of ¹²⁵I-AP was significantly lower in the blood and urinary bladder of mice receiving oral administration of both ¹²⁵I-AP and bromosulfalein than those receiving only ¹²⁵I-AP, but significantly higher in the small intestine due to inhibition of OATPs and/or MRPs. This study indicates that whole-body distribution after oral ¹²⁵I-AP administration can be used to estimate gastrointestinal absorption in the small intestine via OATPs, OATs, and/or MRPs by measuring radioactivity in the urinary bladder.

A single high-dose irradiation changes accumulation of methotrexate and gene expression levels of SLC and ABC transporters in cancer cells

Chemoradiotherapy is frequently used to treat cancer. Stereotactic body radiotherapy (SBRT) is a single high-dose radiotherapy used to treat a variety of cancers. The anticancer drug methotrexate (MTX) shows affinity for solute carrier (SLC) and ATP-binding cassette (ABC) transporters. This study investigated relationships between accumulation of methotrexate and gene expression levels of solute carrier and ATP-binding cassette transporters in cancer cells after a single and high-dose X-ray irradiation. Cancer cell lines were selected from lung and cervical cancer cell line that are commonly used for stereotactic body radiotherapy and effective with methotrexate. We examined expression levels of organic anion-transporting polypeptide (OATP)1B1, OATP1B3, OATP1B7, and organic anion transporter (OAT)1 as solute carrier transporters and multidrug resistance-associated protein (MRP)1 and MRP2 as ATP-binding cassette transporters, using real-time polymerase chain reaction and accumulation of ³H-MTX in cancer cells after 10-Gy irradiation, assuming stereotactic body radiotherapy. Cells were divided into three groups: Control without irradiation; 4 h after irradiation; and 24 h after irradiation. In control, gene expression levels of OAT1 in all cells was below the limit of measurement. After irradiation, gene expression levels of OATP1B1/1B3/1B7 showed changes in each cell line. Gene expression levels of MRP1/2 tended to increase after irradiation. Gene expression levels of OATP1B1/1B3/1B7 were much lower than those of MRP1/2. Accumulation of ³H-MTX tended to decrease over time after irradiation. Irradiation of cancer cells thus alters gene expression levels of both solute carrier transporters (OATP1B1/1B3/1B7) and ABC transporters (MRP1/2) and decreases accumulation of ³H-MTX in cancer cells over time due to elevated expression of MRP1/2.

Measurement of Hepatic CYP3A4 and 2D6 Activity Using Radioiodine-Labeled O-Desmethylvenlafaxine

Drug metabolizing enzyme activity is affected by various factors such as drug–drug interactions, and a method to quantify drug metabolizing enzyme activity in real time is needed. In this study, we developed a novel radiopharmaceutical for quantitative imaging to estimate hepatic CYP3A4 and CYP2D6 activity. Iodine-123- and 125-labeled O-desmethylvenlafaxine (123/125I-ODV) was obtained with high labeling and purity, and its metabolism was found to strongly involve CYP3A4 and CYP2D6. SPECT imaging in normal mice showed that the administered 123I-ODV accumulated early in the liver and was excreted into the gallbladder, as evaluated by time activity curves. In its biological distribution, 125I-ODV administered to mice accumulated early in the liver, and only the metabolite of 125I-ODV was quickly excreted into the bile. In CYP3A4- and CYP2D6-inhibited model mice, the accumulation in bile decreased more than in normal mice, indicating inhibition of metabolite production. These results indicated that imaging and quantifying the accumulation of radioactive metabolites in excretory organs will aid in determining the dosages of various drugs metabolized by CYP3A4 and CYP2D6 for individualized medicine. Thus, 123/125I-ODV has the potential to direct, comprehensive detection and measurement of hepatic CYP3A4 and CYP2D6 activity by a simple and less invasive approach.

Indirect SPECT Imaging Evaluation for Possible Nose-to-Brain Drug Delivery Using a Compound with Poor Blood–Brain Barrier Permeability in Mice

Single-photon emission computed tomography (SPECT) imaging using intravenous radioactive ligand administration to indirectly evaluate the time-dependent effect of intranasal drugs with poor blood-brain barrier permeability on brain drug distributions in mice was evaluated. The biodistribution was examined using domperidone, a dopamine D2 receptor ligand, as the model drug, with intranasal administration at 0, 15, or 30 min before intravenous [123I]IBZM administration. In the striatum, [123I]IBZM accumulation was significantly lower after intranasal (IN) domperidone administration than in controls 15 min after intravenous [125I]IBZM administration. [123I]IBZM SPECT was acquired with intravenous (IV) or IN domperidone administration 15 min before [123I]IBZM, and time–activity curves were obtained. In the striatum, [123I]IBZM accumulation was clearly lower in the IN group than in the control and IV groups. Time–activity curves showed no significant difference between the control and IV groups in the striatum, and values were significantly lowest during the first 10 min in the IN group. In the IN group, binding potential and % of receptor occupancy were significantly lower and higher, respectively, compared to the control and IV groups. Thus, brain-migrated domperidone inhibited D2R binding of [123I]IBZM. SPECT imaging is suitable for research to indirectly explore nose-to-brain drug delivery and locus-specific biological distribution.

123I-BMIPP, a Radiopharmaceutical for Myocardial Fatty Acid Metabolism Scintigraphy, Could Be Utilized in Bacterial Infection Imaging

In this study, we evaluated the use of 15-(4-123I-iodophenyl)-3(R,S)-methylpentadecanoic acid (123I-BMIPP) to visualize fatty acid metabolism in bacteria for bacterial infection imaging. We found that 123I-BMIPP, which is used for fatty acid metabolism scintigraphy in Japan, accumulated markedly in Escherichia coli EC-14 similar to 18F-FDG, which has previously been studied for bacterial imaging. To elucidate the underlying mechanism, we evaluated changes in 123I-BMIPP accumulation under low-temperature conditions and in the presence of a CD36 inhibitor. The uptake of 123I-BMIPP by EC-14 was mediated via the CD36-like fatty-acid-transporting membrane protein and accumulated by fatty acid metabolism. In model mice infected with EC-14, the biological distribution and whole-body imaging were assessed using 123I-BMIPP and 18F-FDG. The 123I-BMIPP biodistribution study showed that, 8 h after infection, the ratio of 123I-BMIPP accumulated in infected muscle to that in control muscle was 1.31 at 60 min after 123I-BMIPP injection. In whole-body imaging 1.5 h after 123I-BMIPP administration and 9.5 h after infection, infected muscle exhibited a 1.33-times higher contrast than non-infected muscle. Thus, 123I-BMIPP shows potential for visualizing fatty acid metabolism of bacteria for imaging bacterial infections.

Comparison of L- and D-Amino Acids for Bacterial Imaging in Lung Infection Mouse Model

The effectiveness of L- and D-amino acids for detecting the early stage of infection in bacterial imaging was compared. We evaluated the accumulation of ³H-L-methionine (Met), ³H-D-Met, ³H-L-alanine (Ala), and ³H-D-Ala in E. coli EC-14 and HaCaT cells. Biological distribution was assessed in control and lung-infection-model mice with EC-14 using ³H-L- and D-Met, and ¹⁸F-FDG. A maximum accumulation of ³H-L- and D-Met, and ³H-L- and D-Ala occurred in the growth phase of EC-14 in vitro. The accumulation of ³H-L-Met and L-Ala was greater than that of ³H-D-Met and D-Ala in both EC-14 and HaCaT cells. For all radiotracers, the accumulation was greater in EC-14 than in HaCaT cells at early time points. The accumulation was identified at 5 min after injection in EC-14, whereas the accumulation gradually increased in HaCaT cells over time. There was little difference in biodistribution between ³H-L-and D-Met except in the brain. ³H-L- and D-Met were sensitive for detecting areas of infection after the spread of bacteria throughout the body, whereas ¹⁸F-FDG mainly detected primary infection areas. Therefore, ¹¹C-L- and D-Met, radioisotopes that differ only in terms of ³H labeling, could be superior to ¹⁸F-FDG for detecting bacterial infection in lung-infection-model mice.

Inhibition of the Hepatic Uptake of 99mTc-Tetrofosmin Using an Organic Cation Transporter Blocker

The accumulation of high levels of ^99mTc-tetrofosmin (^99mTc-TF) in the hepatobiliary system can lead to imaging artifacts and interference with diagnosis. The present study investigated the transport mechanisms of ^99mTc-TF and attempted to apply competitive inhibition using a specific inhibitor to reduce ^99mTc-TF hepatic accumulation. In this in vitro study, ^99mTc-TF was incubated in HEK293 cells expressing human organic anion transporting polypeptide 1B1 (OATP1B1), OATP1B3, OATP2B1, organic anion transporter 2 (OAT2), organic cation transporter 1 (OCT1), OCT2, and Na⁺-taurocholate cotransporting polypeptide with or without each specific inhibitor to evaluate the contribution of each transporter to ^99mTc-TF transportation. In vivo studies, dynamic planar imaging, and single photon emission computed tomography (SPECT) experiments with rats were performed to observe alterations to ^99mTc-TF pharmacokinetics using cimetidine (CMT) as an OCT1 inhibitor. Time-activity curves in the liver and heart were acquired from dynamic data, and the ^99mTc-TF uptake ratio was calculated from SPECT. From the in vitro study, ^99mTc-TF was found to be transported by OCT1 and OCT2. When CMT-preloaded rats and control rats were compared, the hepatic accumulation of the ^99mTc-TF was reduced, and the time to peak heart count shifted to an earlier stage. The hepatic accumulation of ^99mTc-TF was markedly suppressed, and the heart-to-liver ratio increased 1.6-fold. The pharmacokinetics of ^99mTc-TF were greatly changed by OCT1 inhibitor. Even in humans, the administration of OCT1 inhibitor before cardiac SPECT examination may reduce ^99mTc-TF hepatic accumulation and contribute to the suppression of artifacts and the improvement of SPECT image quality.

Assessment of drug transporters involved in the urinary secretion of [99mTc]dimercaptosuccinic acid

INTRODUCTION

We clarified the renal uptake and urinary secretion mechanism of [^99mTc]dimercaptosuccinic acid ([^99mTc]DMSA) via drug transporters in renal proximal tubules.

METHODS

[^99mTc]DMSA was added to human embryonic kidney 293 cells expressing human multidrug and toxin extrusion (MATE)1 and MATE2-K, carnitine/organic cation transporter (OCTN)1 and OCTN2, and organic cation transporter (OCT)2; to Flp293 cells expressing human organic anion transporter (OAT)1 and OAT3; and to vesicles expressing P-glycoprotein (P-gp), multidrug resistance associated protein (MRP)2, MRP4, or breast cancer resistance protein with and without probenecid (OAT inhibitor for both OATs and MRPs). Time activity curves of [^99mTc]DMSA with and without probenecid were established using LLC-PK₁ cells. Biodistribution and single photon emission computed tomography (SPECT) imaging in mice were conducted using [^99mTc]DMSA with and without probenecid.

RESULTS

[^99mTc]DMSA uptake was significantly higher in Flp293/OAT3 than in mock cells. Uptake via OAT3 was inhibited by probenecid. [^99mTc]DMSA uptake into vesicles that highly expressed MRP2 was significantly higher in adenosine triphosphate (ATP) than in adenosine monophosphate (AMP), and probenecid decreased uptake to similar levels as that in AMP. In the time activity curves for [^99mTc]DMSA in LLC-PK₁ cells, probenecid loading inhibited accumulation from the basolateral side into LLC-PK₁ cells, whereas accumulation from the apical side into cells gradually increased. Transport of [^99mTc]DMSA from both sides was low. Biodistribution and SPECT imaging studies showed that [^99mTc]DMSA with probenecid loading resulted in significantly higher accumulation in blood, heart, liver, and bladder after [^99mTc]DMSA injection compared with control mice. Probenecid induced significantly lower accumulation in the kidney after [^99mTc]DMSA injection.

CONCLUSIONS

[^99mTc]DMSA accumulates in renal proximal tubular epithelial cells from blood via OAT3 on the basolateral side, and then a small volume of [^99mTc]DMSA will be excreted in urine via MRP2. ADVANCES IN KNOWLEDGE: [^99mTc]DMSA accumulates via OAT3 in renal proximal tubular epithelial cells and is slightly excreted from the cells via MRP2. IMPLICATIONS FOR PATIENT CARE: [^99mTc]DMSA may be useful for measuring renal transport function with OAT3 in patients.

[131I]MIBG exports via MRP transporters and inhibition of the MRP transporters improves accumulation of [131I]MIBG in neuroblastoma

INTRODUCTION

¹³¹I-labeled m-iodobenzylguanidine ([¹³¹I]MIBG) has been used to treat neuroblastoma patients, but [¹³¹I]MIBG may be immediately excreted from the cancer cells by the adenosine triphosphate binding cassette transporters, similar to anticancer drugs. The purpose of this study was to clarify the efflux mechanism of [¹³¹I]MIBG in neuroblastomas and improve accumulation by inhibition of the transporter in neuroblastomas.

METHODS

[¹³¹I]MIBG was incubated in human embryonic kidney (HEK)293 cells expressing human organic anion transporting polypeptide (OATP)1B1, OATP1B3, OATP2B1, organic anion transporter (OAT)1 and OAT2, organic cation transporter (OCT)1 and OCT2, and sodium taurocholate cotransporting polypeptide, and in vesicles expressing P-glycoprotein (MDR1), multidrug resistance associated protein (MRP)1-4, or breast cancer resistance protein with and without MK-571 and probenecid (MRP inhibitors). Time activity curves of [¹³¹I]MIBG with and without MK-571 and probenecid were established using an SK-N-SH neuroblastoma cell line, and transporter expression of multiple drug resistance was measured. Biodistribution and SPECT imaging examinations were conducted using [¹²³I]MIBG with and without probenecid in SK-N-SH-bearing mice.

RESULTS

[¹³¹I]MIBG uptake was significantly higher in OAT1, OAT2, OCT1, and OCT2 than in mock cells. Uptake via OCT1 and OCT2 was little inhibited by MK-571 and probenecid. [¹³¹I]MIBG uptake into vesicles that highly expressed MRP1 or MRP4 was significantly higher in ATP than in AMP, and these inhibitors restored uptake to levels similar to that in AMP. Examining the time activity curves for [¹³¹I]MIBG in SK-N-SH cells, higher expressions of MDR1, MRP1, MRP4, and MK-571, or probenecid loading produced significantly higher uptake than in control at most incubation times. The ratios of tumors to blood or muscle in SK-N-SH-bearing mice were significantly increased by probenecid loading in comparison with normal mice.

CONCLUSIONS

[¹³¹I]MIBG exports via MRP1 and MRP4 in neuroblastoma. The accumulation and tumor-to-blood or muscle ratios of [¹³¹I]MIBG are improved by inhibition of MRPs with probenecid in neuroblastoma. ADVANCES IN KNOWLEDGE: [¹³¹I]MIBG, widely used for treatment of neuroendocrine tumors including neuroblastoma, is excreted via MRP1 and MRP4 in neuroblastoma.

IMPLICATIONS FOR PATIENT CARE

Loading with probenecid, OAT, and MRP inhibitors improves [¹³¹I]MIBG accumulation.

The pharmacological properties of 3-arm or 4-arm DOTA constructs for conjugation to α-melanocyte-stimulating hormone analogues for melanoma imaging

Background

Although a 3-arm DOTA construct, which has three carboxylic acids, h has been applied for conjugation to many peptides, we investigated if a 4-arm DOTA construct conjugated to peptides improves chemical properties for melanoma imaging of the melanocortin 1 receptor compared to 3-arm DOTA-conjugated peptides.

Methods

Specific activities, radiolabeling efficiencies, and partition coefficients were evaluated using ¹¹¹In-labeled 3-arm and 4-arm DOTA-α-melanocyte-stimulating hormone (MSH). For assessment of MC1-R affinity and accumulation in tumor cells in vitro, B16-F1 melanoma and/or 4T1 breast cancer cells were incubated with ¹¹¹In-labeled 3-arm and 4-arm DOTA-α-MSH with and without α-MSH as a substrate. The stability was evaluated using mouse liver homogenates and plasma. Biological distribution and whole-body single photon emission computed tomography imaging of ¹¹¹In-labeled 3-arm and 4-arm DOTA-α-MSH were obtained using B16-F1 melanoma-bearing mice.

Results

Specific activities and radiolabeling efficiencies of both radiotracers were about 1.2 MBq/nM and 90–95%, respectively. The partition coefficients were −0.28 ± 0.03 for ¹¹¹In-labeled 3-arm DOTA-α-MSH and −0.13 ± 0.04 for ¹¹¹In-labeled 4-arm DOTA-α-MSH. Although accumulation was significantly inhibited by α-MSH in B16-F1 cells, the inhibition rate of ¹¹¹In-labeled 4-arm DOTA-α-MSH was lower than that of ¹¹¹In-labeled 3-arm DOTA-α-MSH. ¹¹¹In-labeled 4-arm DOTA-α-MSH was taken up early into B16-F1 cells and showed higher accumulation than ¹¹¹In-labeled 3-arm DOTA-α-MSH after 10 min of incubation. Although these stabilities were relatively high, the stability of ¹¹¹In-labeled 4-arm DOTA-α-MSH was higher than that of ¹¹¹In-labeled 3-arm DOTA-α-MSH. Regarding biological distribution, ¹¹¹In-labeled 4-arm DOTA-α-MSH showed significantly lower average renal accumulation (1.38-fold) and significantly higher average melanoma accumulation (1.32-fold) than ¹¹¹In-labeled 3-arm DOTA-α-MSH at all acquisition times. ¹¹¹In-labeled 4-arm DOTA-α-MSH showed significantly higher melanoma-to-kidney, melanoma-to-blood, and melanoma-to-muscle ratios than ¹¹¹In-labeled 3-arm DOTA-α-MSH.

Conclusions

The 4-arm DOTA construct has better chemical properties for peptide radiotracers than the 3-arm DOTA construct.

Development of radioiodine labeled acetaminophen for specific, high-contrast imaging of malignant melanoma

INTRODUCTION

Due to its poor prognosis, specific imaging for early detection of malignant melanoma is strongly desired. Although radioiodine labeled 4-hydroxyphenylcysteamine, which we previously developed, has good affinity for tyrosinase, an enzyme in the melanin metabolic pathway, image contrast of the melanoma:organ ratios is not sufficiently high for detection of primary melanoma and metastases at early injection times. In this study, we developed radioiodine labeled acetaminophen (I-AP) for specific, high-contrast imaging of malignant melanoma.

METHODS

Radioiodine-125-labeled AP (¹²⁵I-AP) was prepared using the chloramine-T method under no carrier-added conditions. Accumulation of radioactivity and the mechanism were evaluated in vitro using B16 melanoma cells incubated with ¹²⁵I-AP or ¹⁴C(U)-labeled AP (¹⁴C-AP) with and without l-tyrosine as a substrate of tyrosinase, phenylthiourea as an inhibitor of tyrosinase, and thymidine as an inhibitor of DNA polymerase. The biological distribution of radioactivity in B16 melanoma-bearing mice was evaluated to determine the accumulation of ¹²⁵I-AP. The stability of ¹²⁵I-AP over time was evaluated in mice.

RESULTS

The labeling efficiency and radiochemical purity of ¹²⁵I-AP were >80% and 95%, respectively. Accumulation of ¹²⁵I-AP was higher than that of ¹⁴C-AP at 60 min of incubation in vitro. The affinity of ¹⁴C-AP for tyrosinase and DNA polymerase was higher than that of ¹²⁵I-AP, whereas the V_max of ¹²⁵I-AP was higher than that of ¹⁴C-AP. ¹²⁵I-AP showed the highest accumulation in the gall bladder, and clearance from the blood and kidney was rapid. Melanoma:muscle and melanoma:normal skin ratios of ¹²⁵I-AP for imaging contrast were the highest at 15 min after injection, whereas the melanoma:blood and melanoma:bone ratios gradually increased over time. ¹²⁵I-AP remained stable for 60 min after injection in mice.

CONCLUSIONS

¹²⁵I-AP has affinity for tyrosinase and high image contrast at early time points after injection. Therefore, ¹²³I-AP imaging has great potential for specific, high-contrast detection of malignant melanoma. ADVANCES IN KNOWLEDGE: ¹²³I-AP will provide specific, high-contrast imaging for malignant melanoma at early injection times. IMPLICATIONS FOR PATIENT CARE: ¹²³I-AP has good potential for the diagnosis of malignant melanoma compared with ¹²³I-labeled 4-hydroxyphenylcysteamine, which we previously developed.

Synergistic anti-AML effects of the LSD1 inhibitor T-3775440 and the NEDD8-activating enzyme inhibitor pevonedistat via transdifferentiation and DNA rereplication

Lysine-specific demethylase 1A (LSD1, KDM1A) specifically demethylates di- and monomethylated histones H3K4 and K9, resulting in context-dependent transcriptional repression or activation. We previously identified an irreversible LSD1 inhibitor T-3775440, which exerts antileukemic activities in a subset of acute myeloid leukemia (AML) cell lines by inducing cell transdifferentiation. The NEDD8-activating enzyme inhibitor pevonedistat (MLN4924, TAK-924) is an investigational drug with antiproliferative activities in AML, and is also reported to induce cell differentiation. We therefore tested the combination of these two agents in AML models. The combination treatment resulted in synergistic growth inhibition of AML cells, accompanied by enhanced transdifferentiation of an erythroid leukemia lineage into granulomonocytic-like lineage cells. In addition, pevonedistat-induced rereplication stress during the S phase was greatly augmented by concomitant treatment with T-3775440, as reflected by the increased induction of apoptosis. We further demonstrated that the combination treatment was markedly effective in subcutaneous tumor xenograft models as well as in a disseminated model of AML, leading to tumor eradication or prolonged survival in T-3775440/pevonedistat cotreated mice. Our findings indicate the therapeutic potential of the combination of LSD1 inhibitors and pevonedistat for the treatment of AML.

Differences in accumulation and the transport mechanism of l- and d-methionine in high- and low-grade human glioma cells

INTRODUCTION

Although [S-methyl-11C]-labeled L-methionine and D-methionine (¹¹C-L-MET and ¹¹C-D-MET) are useful radiotracers for positron emission tomography imaging of brain tumors, it is not known whether the accumulation and transport mechanisms underlying uptake of ¹¹C-D-MET and ¹¹C-L-MET are the same. ¹¹C-L-MET is mainly taken up by the amino acid transport system L. We evaluated accumulation and the transport mechanism of D-MET in high- and low-grade human glioma cells in vitro.

METHODS

The expression of transport system genes in high- (A172 and T98G) and low-grade (SW1088 and Hs683) glioma cells was quantitatively analyzed. Accumulation of [S-methyl-³H]-L-MET (³H-L-MET) and [S-methyl-³H]-D-MET (³H-D-MET) in these cells was compared during 60min of incubation. The transport mechanism of ³H-L-MET and ³H-D-MET was investigated by incubating the cells with these compounds and examining the effect of the inhibitors 2-amino-2-norbornane-carboxylic acid or α-(methylamino) isobutyric acid.

RESULTS

Absolute expression levels of system L and system alanine-serine-cysteine (ASC) in high-grade glioma cells were higher than in low-grade cells. In high-grade glioma cells, expression of system ASC genes was higher than that of system L genes. ³H-D-MET, which is transported by systems L and ASC, accumulated at higher levels than ³H-L-MET at all incubation times because ³H-D-MET is more sensitive to system ASC than ³H-L-MET. Conversely, in low-grade glioma cells with lower expression of system L and ASC, ³H-D-MET accumulated at higher levels than ³H-L-MET in early incubation times because ³H-D-MET may be more sensitive to system ASC than system L.

CONCLUSION

³H-D-MET was mainly transported by systems L and ASC and sensitive to system ASC, whereas ³H-L-MET was transported by system L in human glioma cells. In vitro, the accumulation of ³H-D-MET was significantly higher than that of ³H-L-MET during the entire incubation time in high-grade glioma cells, and in early incubation times in low-grade glioma cells.

Paraneoplastic neurological syndrome due to burned-out testicular tumor showing hot cross-bun sign

BACKGROUND

Paraneoplastic neurological syndromes (PNS) are rare remote effect of cancer. The antibodies and tumors associated with PNS have been well described, but there are still many clinically suspected cases in which no tumor or antibody can be identified. This is the first report of PNS showing hot cross-bun sign and caused by exceptionally rare underlying malignancy, such as burned-out testicular tumor.

CASE PRESENTATION

A 42-year-old man presented subacute progression of hearing loss and cerebellar ataxia. Cerebrospinal fluid showed continuous inflammation and magnetic resonance imaging (MRI) revealed cerebellar atrophy and hot cross-bun sign. Resection of tumors improved both laboratory findings and neurological signs and their pathology was seminoma.

CONCLUSION

Seminoma can cause PNS showing 8th cranial nerve palsy, cerebellar, and brainstem atrophy with hot cross-bun sign on MRI study. Extensive screening for onconeural antibodies was negative and thereby suggested that unknown antibodies worked for both antitumor immunity and induction of PNS.

Simultaneous acquisition of (99m)Tc- and (123)I-labeled radiotracers using a preclinical SPECT scanner with CZT detectors

OBJECTIVE

Simultaneous acquisition of (99m)Tc and (123)I was evaluated using a preclinical SPECT scanner with cadmium zinc telluride (CZT)-based detectors.

METHODS

10-ml cylindrical syringes contained about 37 MBq (99m)Tc-tetrofosmin ((99m)Tc-TF) or 37 MBq (123)I-15-(p-iodophenyl)-3R,S-methyl pentadecanoic acid ((123)I-BMIPP) were used to assess the relationship between these SPECT radioactive counts and radioactivity. Two 10-ml syringes contained 100 or 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP to assess the influence of (99m)Tc upscatter and (123)I downscatter, respectively. A rat-sized cylindrical phantom also contained both 100 or 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP. The two 10-ml syringes and phantom were scanned using a pinhole collimator for rats. Myocardial infarction model rats were examined using 300 MBq (99m)Tc-TF and 100 MBq (123)I-BMIPP. Two 1-ml syringes contained 105 MBq (99m)Tc-labeled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) and 35 MBq (123)I-labeled N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane ((123)I-FP-CIT). The two 1-ml syringes were scanned using a pinhole collimator for mice. Normal mice were examined using 105 MBq (99m)Tc-HMPAO and 35 MBq (123)I-FP-CIT.

RESULTS

The relationship between SPECT radioactive counts and radioactivity was excellent. Downscatter contamination of (123)I-BMIPP exhibited fewer radioactive counts for 300 MBq (99m)Tc-TF without scatter correction (SC) in 125-150 keV. There was no upscatter contamination of (99m)Tc-TF in 150-175 keV. In the rat-sized phantom, the radioactive count ratio decreased to 4.0 % for 300 MBq (99m)Tc-TF without SC in 125-150 keV. In the rats, myocardial images and radioactive counts of (99m)Tc-TF with the dual tracer were identical to those of the (99m)Tc-TF single injection. Downscatter contamination of (123)I-FP-CIT was 4.2 % without SC in 125-150 keV. In the first injection of (99m)Tc-HMPAO and second injection of (123)I-FP-CIT, brain images and radioactive counts of (99m)Tc-HMPAO with the dual tracer in normal mice also were the similar to those of the (99m)Tc-HMPAO single injection. In the first injection of (123)I-FP-CIT and second injection of (99m)Tc-HMPAO, the brain images and radioactive counts with the dual tracer were not much different from those of the (123)I-FP-CIT single injection.

CONCLUSIONS

Dual-tracer imaging of (99m)Tc- and (123)I-labeled radiotracers is feasible in a preclinical SPECT scanner with CZT detector. When higher radioactivity of (99m)Tc-labeled radiotracers relative to (123)I-labeled radiotracers is applied, correction methods are not necessarily required for the quantification of (99m)Tc- and (123)I-labeled radiotracers when using a preclinical SPECT scanner with CZT detector.

Impact of injection dose, post-reconstruction filtering, and collimator choice on image quality of myocardial perfusion SPECT using cadmium-zinc telluride detectors in the rat

Background

The aims of this study were (1) to evaluate the impact of injection dose, post-reconstruction filtering, and collimator choice on image quality of myocardial perfusion single-photon emission computed tomography (SPECT) using cadmium-zinc telluride (CZT) detectors and (2) to determine how these factors affect measured infarct size in the in vivo rat.

Methods

Twenty-four healthy and eight myocardial infarct (MI) rats underwent myocardial perfusion SPECT imaging after injection of various doses (25 to 200 MBq) of ^99mTc-tetrofosmin using a standard (STD) five-pinhole collimator and high-sensitivity (HS) five-pinhole collimator. Image quality score, contrast-to-noise ratio, sharpness index, coefficient of variation (CV), and measured defect size were assessed as measures of image quality.

Results

The image quality score increased and CV decreased as a function of injection dose. The contrast-to-noise ratio increased and sharpness index decreased as a function of Gaussian kernel size. When STD and HS were compared, HS tended to show higher image quality score and lower CV than STD. The use of post-reconstruction filter significantly improved image quality score and lessened CV. The reproducibility of defect size measurements, as assessed by intraclass correlation coefficients (ICC), between the collimators was poor-to-moderate (ICC = −0.31~0.57) with low (25 MBq) injection dose and with no or light (1.5-mm kernel size) filtering, whereas it was good-to-excellent (ICC = 0.75~0.97) with high (200 MBq) dose or low dose with heavy (2.5-mm kernel size) filtering. The filtering-related reproducibility was poor (ICC = −0.18~0.17) for STD with low injection dose, whereas it was good-to-excellent (ICC = 0.79~0.89) for HS. Furthermore, there was a filtering-related underestimation of defect size particularly with the use of heavy smoothing.

Conclusions

Appropriate imaging setting is important to obtain high quality images and thereby reliable measurements using a preclinical myocardial SPECT in the rat. When only a low injection dose (25 MBq) is allowed, we would recommend to use HS with light (1.5-mm kernel size) filtering.

A strategy for improving FDG accumulation for early detection of metastasis from primary pancreatic cancer: stimulation of the Warburg effect in AsPC-1 cells

INTRODUCTION

Early detection and/or prediction of metastasis provide more prognostic relevance than local recurrence. Direct spread into the peritoneum is frequently found in pancreatic cancer patients, but positron emission tomography (PET) with 2-deoxy-2-fluoro-d-glucose (FDG) is not useful for identifying such metastasis. We investigated a method to enhance FDG accumulation using AsPC-1 human ascites tumor cells.

METHODS

(14)C-FDG accumulation was assessed under the following conditions: 1) characteristics of (14)C-FDG transport were examined using phloridzin, a Na(+)-free buffer, and various hexoses, and 2) accumulation of (14)C-FDG was measured in cells that were pretreated with hexose for various time periods, and activity of 6-phosphofructo-1-kinase (PFK-1) was assayed.

RESULTS

(14)C-FDG transport into AsPC-1 cells was mediated primarily by a Na(+)-independent transport mechanism. Aldohexoses such as d-glucose, D-mannose, and D-galactose inhibited (14)C-FDG transport. Cells pretreated with d-glucose, D-mannose, or D-fructose exhibited augmented (14)C-FDG accumulation. Pretreatment with higher concentrations of D-glucose or D-fructose tended to increase PFK-1 activity.

CONCLUSIONS

Very little information has been published about the association between PFK-1 and FDG accumulation, and we confirmed the impacts of various hexoses on the activity of PFK-1 and FDG accumulation in AsPC-1 cells. Clarifying the relevance of PFK-1 in FDG accumulation will contribute to developing new features of FDG-PET, because PFK-1 is the main regulator of glycolysis.

Development of radioiodine-labeled 4-hydroxyphenylcysteamine for specific diagnosis of malignant melanoma

INTRODUCTION

A specific diagnosis for melanoma is strongly desired because malignant melanoma has poor prognosis. In a previous study, although radioiodine-125-labeled 4-hydroxyphenyl-L-cysteine ((125)I-L-PC) was found to have good substrate affinity for tyrosinase enzyme in the melanin metabolic pathway, (123/131)I-L-PC had insufficient substrate affinity for tyrosinase to diagnose melanoma. In this study, we synthesized 4-hydroxyphenylcysteamine (4-PCA) and developed a novel radioiodine-125-labeled 4-hydroxyphenylcysteamine ((125)I-PCA) to increase affinity for the melanin biosynthesis pathway.

METHODS

4-PCA was separated with 2-hydroxyphenylcysteamine (2-PCA), which is an isomer of 4-PCA, and was examined using melting point, proton nuclear magnetic resonance, mass spectrometry and elemental analysis. (125)I-PCA was prepared using the chloramine-T method under no-carrier added conditions. We performed biodistribution experiments using B16 melanoma-bearing mice using (125)I-PCA, (125)I-L-PC, (125)I-α-methyl-L-tyrosine, (123)I-m-iodobenzylguanidine and (67)Ga-citrate. In vitro assay was performed with B16 melanoma cells, and affinity for tyrosinase, DNA polymerase and amino acid transport was evaluated using phenylthiourea, thymidine, ouabine and L-tyrosine inhibitor. In addition, partition coefficients of (125)I-PCA were evaluated.

RESULTS

In the synthesis of 4-PCA, analysis values did not differ between calculated and reported values, and 4-PCA was separated from 2-PCA at high purity. In biodistribution experiments, (125)I-PCA was accumulated and retained in B16 melanoma cells when compared with (125)I-L-PC. (125)I-PCA showed the highest values at 60 min after radiotracer injection in melanoma-to-muscle ratios, melanoma-to-blood ratios and melanoma-to-skin ratios. Accumulation of (125)I-PCA was significantly inhibited by phenylthiourea and thymidine. Partition coefficients of (125)I-PCA were lower than those of N-isopropyl-p-[(123)I]iodoamphetamine and were not significantly different from (125)I-L-PC.

CONCLUSIONS

(125)I-PCA is a better substrate for tyrosinase and DNA polymerase and has higher uptake and longer retention in B16 melanoma cells when compared with (125)I-L-PC. Therefore, (123/131)I-PCA has good potential for diagnosis for malignant melanoma.

ADVANCE IN KNOWLEDGE

(125)I-PCA will be a specific diagnosis tool for malignant melanoma.

IMPLICATIONS FOR PATIENT CARE

(123/131)I-PCA has good potential for the diagnosis of malignant melanoma when compared with other SPECT tracers, as well as anti-melanoma chemotherapeutic drugs.

Performance evaluation of the eXplore speCZT preclinical imaging system

OBJECTIVE

The eXplore speCZT is a recently introduced cadmium zinc telluride-based preclinical SPECT system that has a stationary detector design with interchangeable rotating collimators. Our aim was to evaluate the performance of the eXplore speCZT using 99mTc-sources. In particular, the image quality was assessed using the National Electrical Manufacturers Association NU-4 image quality phantom as well as an in vivo mouse.

METHODS

Energy resolution, sensitivity and spatial resolution were measured using 99mTc sources. Image quality was assessed using NU-4 image quality phantom. The measurements were performed for 4 available collimators: (1) mouse 7-pinhole collimator (mouse PH); (2) mouse 8-slit collimator (mouse SL); (3) rat 5-pinhole collimator (rat PH); and (4) rat 5-slit collimator (rat SL). Furthermore, a mouse bone imaging study was performed using mouse PH and mouse SL.

RESULTS

The system achieved the energy resolution of 5.5% in full-width at half maximum (FWHM) at 140 keV using a 99mTc source. Without resolution recovery function, the system provided a near millimeter transaxial and axial spatial resolution using mouse PH. Mouse SL and rat SL provided reasonably good transaxial (1.79-2.00 mm in FWHM), but much worse axial resolutions (4.55-4.96 mm in FWHM). The use of resolution recovery significantly improved spatial resolution by in average 31±3 or 35±4% in FWHM or full-width at tenth maximum, respectively. In particular, a sub-millimeter resolution of 0.71 mm in FWHM was achieved in either transaxial or axial direction with mouse PH. Using NU-4 phantom, the uniformity of slit collimators as expressed as percentage standard deviation was generally better than that of pinhole collimators. The use of resolution recovery substantially improved uniformity for all the collimators tested, but caused some overestimation in recovery coefficient. Reconstruction settings such as iteration or subset number significantly affected image quality measures. Finally, bone images of acceptable quality were obtained in in vivo mouse using mouse PH with resolution recovery.

CONCLUSIONS

The overall performance shows that the eXplore speCZT system is suitable for preclinical imaging-based research using small-animals.

Transport mechanisms of hepatic uptake and bile excretion in clinical hepatobiliary scintigraphy with 99mTc-N-pyridoxyl-5-methyltryptophan

INTRODUCTION

In clinical hepatobiliary scintigraphy, (99m)Tc-N-pyridoxyl-5-methyltryptophan ((99m)Tc-PMT) is an effective radiotracer among the (99m)Tc-pyridoxylaminates. However, the mechanisms of human hepatic uptake and bile excretion transport of (99m)Tc-PMT have not been determined. We thus investigated the transport mechanisms of human hepatic uptake and bile excretion in hepatobiliary scintigraphy with (99m)Tc-PMT.

METHODS

Four solute carrier (SLC) transporters involved in hepatic uptake were evaluated using human embryonic kidney (HEK) and HeLa cells with high expression of SLC transporters (organic anion transporting polypeptide (OATP)1B1, OATP1B3, OATP2B1, organic anion transporters (OAT)2 and organic cation transporters (OCT)1) after 5 min of (99m)Tc-PMT incubation. Metabolic analysis of (99m)Tc-PMT was performed using pooled human liver S9. Adenosine triphosphate (ATP)-binding cassette (ABC) transporters for bile excretion were examined using hepatic ABC transporter vesicles human expressing multiple drug resistance 1 (MDR1), multidrug resistance-associated protein 2 (MRP2), breast cancer resistance protein or bile salt export pump. (99m)Tc-PMT was incubated for 1, 3 and 5 min with ATP or adenosine monophosphate and these vesicles. SPECT scans were performed in normal and Eisai hyperbilirubinemic (EHBR) model rats, deficient in Mrp2 transporters, without and with verapamil (rat Mdr1 and human MDR1 inhibitor) after intravenous injection of (99m)Tc-PMT.

RESULTS

Uptake of (99m)Tc-PMT in HEK293/OATP1B1 and HeLa/OATP1B3 was significantly higher than that in HEK293- and HeLa-mock cells. (99m)Tc-PMT was not metabolized in the human liver S9. In vesicles with high expression of ABC transporters, uptake of MDR1 or MRP2 was significantly higher at all incubation times. Bile excretion of (99m)Tc-PMT was also identified by comparison between normal and EHBR rats with and without verapamil on in-vivo imaging.

CONCLUSIONS

Human hepatic uptake of (99m)Tc-PMT was transferred by OATP1B1 and OATP1B3, and excretion into bile canaliculi via MDR1 and MRP2. (99m)Tc-PMT hepatobiliary scintigraphy may be a useful ligand as a noninvasive method of visualizing and quantifying hepatobiliary transporter functionality, which could predict drug pharmacokinetics.

Differential increases in blood flow velocity in the middle cerebral artery after tourniquet deflation during sevoflurane, isoflurane or propofol anaesthesia

The purpose of this study was to examine the comparative effects of sevoflurane, isoflurane or propofol on cerebral blood flow velocity after tourniquet deflation during orthopaedic surgery. Thirty patients undergoing elective orthopaedic surgery were randomly divided into sevoflurane, isoflurane and propofol groups. Anaesthesia was maintained with sevoflurane, isoflurane or propofol infusion in 33% oxygen and 67% nitrous oxide, in whatever concentrations were necessary to keep bispectral index values between 45 and 50. Ventilatory rate or tidal volume was adjusted to target PaCO2 of 35 mmHg. A 2.0 MHz transcranial Doppler probe was attached to the patient's head at the temporal window and mean blood flow velocity in the middle cerebral artery was continuously measured. The extremity was exsanguinated with an Esmarch bandage and the pneumatic tourniquet was inflated to a pressure of 450 mmHg. Arterial blood pressure, heart rate, velocity in the middle cerebral artery and arterial blood gas analysis were measured every minute for 10 minutes after release of the tourniquet in all three groups. Velocity in the middle cerebral artery in the three groups increased for five minutes after tourniquet deflation. Because of the different cerebrovascular effects of the three agents, the degree of increase in flow velocity in the isoflurane group was greater than in the other two groups, the change in flow velocity in the propofol group being the lowest (at three minutes after deflation 40 +/- 7%, 32 +/- 6% and 28 +/- 10% in the isoflurane, sevoflurane and propofol groups respectively, P < 0.05).

Tumour necrosis factor alpha signalling through activation of Kupffer cells plays an essential role in liver fibrosis of non-alcoholic steatohepatitis in mice

BACKGROUND

While tumour necrosis factor alpha (TNF-alpha) appears to be associated with the development of non-alcoholic steatohepatitis (NASH), its precise role in the pathogenesis of NASH is not well understood.

METHODS

Male mice deficient in both TNF receptors 1 (TNFR1) and 2 (TNFR2) (TNFRDKO mice) and wild-type mice were fed a methionine and choline deficient (MCD) diet or a control diet for eight weeks, maintaining isoenergetic intake.

RESULTS

MCD dietary feeding of TNFRDKO mice for eight weeks resulted in attenuated liver steatosis and fibrosis compared with control wild-type mice. In the liver, the number of activated hepatic Kupffer cells recruited was significantly decreased in TNFRDKO mice after MCD dietary feeding. In addition, hepatic induction of TNF-alpha, vascular cell adhesion molecule 1, and intracellular adhesion molecule 1 was significantly suppressed in TNFRDKO mice. While in control animals MCD dietary feeding dramatically increased mRNA expression of tissue inhibitor of metalloproteinase 1 (TIMP-1) in both whole liver and hepatic stellate cells, concomitant with enhanced activation of hepatic stellate cells, both factors were significantly lower in TNFRDKO mice. In primary cultures, TNF-alpha administration enhanced TIMP-1 mRNA expression in activated hepatic stellate cells and suppressed apoptotic induction in activated hepatic stellate cells. Inhibition of TNF induced TIMP-1 upregulation by TIMP-1 specific siRNA reversed the apoptotic suppression seen in hepatic stellate cells.

CONCLUSIONS

Enhancement of the TNF-alpha/TNFR mediated signalling pathway via activation of Kupffer cells in an autocrine or paracrine manner may be critically involved in the pathogenesis of liver fibrosis in this NASH animal model.

Titration emulation: a computer-assisted technique that simplifies the quantification of anti-dsDNA antibodies using the Crithidia luciliae assay

Titers of anti-double-stranded (ds) DNA antibodies in sera from patients with systemic lupus erythematosus (SLE) using the Crithidia luciliae assay method were compared by conventional titration vs the titration emulation method (ImageTiter) to evaluate whether the latter assay can replace manual titration. Titers by the two methods were identical or within one dilution in 98% (41/42) of samples. A single sample showed a two-dilution difference. Titration emulation showed a tendency to under-estimate the titer of high titer anti-dsDNA samples, although the difference was small. Titration emulation is a suitable alternative to the conventional titration method, offering an accurate and cost-effective approach to quantification of anti-dsDNA antibodies.

The effect of fenestration procedure on liver regeneration in a case of polycystic liver disease

We encountered a case of polycystic liver disease for which unroofing and fenestration procedures were performed. The patient was a 55-year-old Japanese female with epigastralgia and abdominal fullness. On computed tomography, millions of low-density areas were seen, particularly in S6, 7, where huge cysts 15 cm in diameter were observed. Magnetic resonance imaging showed a T1 low T2 high-intensity lesion, which was compatible with simple cysts. Unroofing for the cysts in S6, 7 and fenestration of other cysts were performed. Histological examination revealed cuboidal and flat monolayer epithelia with no dysplasia in the wall of the cysts. The postoperative course was uneventful, and the patient's abdominal symptoms remarkably improved. The percentage of the liver volume which was increased in relation to standard liver volume was reduced from 241% (3386 mL: liver parenchyma 750 mL, cysts 2636 mL) to 180% (2525 mL, 1566 mL, 959 mL, respectively) after surgery. The potent mitogen, hepatocyte growth factor, was rapidly increased after the operation and stayed high during the observation period. In this patient, since no liver resection was performed, liver regenerative stimulus was considered to be the loss of space. This phenomenon represents a model of liver regeneration in response to loss of occupied space in an absence of shear stress.

Expression of matrix metalloproteinases during ascorbate-induced differentiation of osteoblastic MC3T3-E1 cells

The mouse calvarial osteoblast MC3T3-E1 cells released 92 kDa and 68 kDa of gelatinase activities into the conditioned media (CMs) from undifferentiated cells. When differentiation was induced by cultivating cells with ascorbate-2-phosphate (AscP), 68-kDa activity increased significantly in parallel with production of 60-kDa activity. These enzymes required Ca2+ and Zn2+ ions for their proteolytic activities. The 68-kDa activity was immunologically identified as latent matrix metalloproteinase 2 (MMP-2). The 92-kDa activity was deduced to be latent MMP-9 based on its molecular mass. The 60-kDa activity band was found to possess both gelatin and beta-casein hydrolyzing activities, indicating that this activity band might comprise the active form of MMP-2 and latent MMP-13. MC3T3-E1 cells were found to express MMP-2, MMP-13, and membrane type (MT)1-MMP genes by Northern blotting. MMP-2 was expressed constitutively. MMP-13 was up-regulated during the growth with AscP. MT1-MMP expression also was modulated by AscP; at the early stage of differentiation, its messenger RNA (mRNA) level increased and then decreased gradually to the control level. These changes in the profiles of MMPs observed here could be attributed to the maturation of collagenous extracellular matrix (ECM) induced by AscP.

Antireflection microstructures fabricated upon fluorine-doped SiO(2) films

Two-dimensional periodic structures were fabricated upon a fluorine-doped SiO(2) film in which the fluorine content changed gradually in the direction of film thickness. The films were deposited by plasma-enhanced chemical-vapor deposition. The film was periodically patterned into a 1-mum period and an ~1-mum -groove depth by inductive coupled plasma reactive-ion etching followed by chemical etching in a diluted HF solution. A surface reflectance of 0.7% was attained at 1.85-mum wavelength, a value that is one fifth as large as the 3.5% Fresnel reflection of a SiO(2) substrate with a flat surface.

Activated protein C prevents endotoxin-induced hypotension in rats by inhibiting excessive production of nitric oxide

BACKGROUND

Excessive production of nitric oxide (NO) by the inducible isoform of NO synthase (iNOS) is critically involved in endotoxin (ET)-induced hypotension. Tumor necrosis factor-alpha (TNF-alpha) plays an important role in induction of iNOS. Because activated protein C (APC), a physiological anticoagulant, inhibits TNF-alpha production, it might prevent hypotension by inhibiting excessive production of NO. In this study, we examined this possibility using a rat model of septic shock.

METHODS AND RESULTS

Intravenous administration of APC prevented both ET-induced hypotension and the increases in plasma levels of NO(2)(-)/NO(3)(-). The hypotension was also inhibited when APC was administered 30 minutes after ET administration. APC inhibited the increases in lung levels of iNOS activity by inhibiting expression of iNOS mRNA in animals given ET. APC significantly inhibited the increases in lung tissue levels of TNF-alpha and expression of TNF-alpha mRNA in animals given ET. Neither DEGR-F.Xa, a selective inhibitor of thrombin generation, nor DIP-APC, an active site-blocked APC, showed any effect on these ET-induced changes. Both inhibition of TNF-alpha production by leukocytopenia and treatment with anti-rat TNF-alpha antibody produced effects similar to those induced by APC. Aminoguanidine, a selective inhibitor of iNOS, inhibited both the hypotension and the increases in plasma levels of NO(2)(-)/NO(3)(-) in this animal model.

CONCLUSIONS

These observations strongly suggest that APC inhibits iNOS induction by decreasing TNF-alpha production, leading to the prevention of ET-induced hypotension. Furthermore, such effects of APC were not dependent on its anticoagulant effects but rather on its serine protease activity.

Purification and characterization of carbaryl hydrolase from Arthrobacter sp. RC100

A carbaryl hydrolase was purified to homogeneity from Arthrobacter sp. strain RC100 by protamine sulfate treatment, ammonium sulfate precipitation, and hydrophobic, anion-exchange, and gel filtration chromatographies. The native enzyme had a molecular mass of 100 kDa and was composed of two identical subunits with molecular masses of 51 kDa. The hydrolase activity was strongly inhibited by DIFP, PMSF, Hg(2+) and paraoxon but not by EDTA. The optimum pH and temperature for the enzyme activity were 9.0 and 50 degrees C, respectively. The enzyme hydrolyzed four N-methylcarbamate insecticides (carbaryl, xylylcarb, metolcarb and XMC), but was not able to hydrolyze fenobucarb, propoxur, and isoprocarb.

Nonpolarizing guided-mode resonant grating filter for oblique incidence

A new type of guided-mode resonant grating filter is described. The filter is independent of polarization state for oblique incidence. The filter has a crossed grating structure, and the plane of incidence on the filter contains the symmetric axis of the grating structure. Theoretical considerations and numerical calculations using two-dimensional rigorous coupled-wave analysis show that a rhombic lattice structure is suitable to such filters. In this configuration an incident light wave is diffracted into the waveguide and is divided into two propagation modes whose directions are symmetric with respect to the plane of incidence. In particular, when the propagation directions of the two modes are perpendicular to each other, the fill factor of grating structure can be approximately 50%. The filter was designed for an incident angle of 45 degrees. Tolerances of setting errors and fabrication errors for this filter were estimated by numerical calculations.

KL-6 as a novel marker for activities of interstitial pneumonia in connective tissue diseases

The objective of this study was to determine the role of serum KL-6 levels as a marker for the activity of interstitial pneumonia in patients with connective tissue diseases. The serum concentrations of KL-6, a glycoprotein produced mainly by pulmonary type II epithelial cells, were measured in 21 patients with connective tissue disease. The activity of interstitial pneumonia was compared with the associated serum KL-6 concentrations. Serum KL-6 concentrations in patients with interstitial pneumonia were significantly higher than those in the controls. Among patients with active interstitial pneumonia, serum KL-6 concentrations following the treatment (after improvement) were significantly lower than the pretreatment values. The extent of the pulmonary fibrosis correlated positively with the serum KL-6 concentrations during the inactive phase of the interstitial pneumonia. These results suggest that sequential measurement of serum KL-6 levels is a new and useful means for the evaluation of interstitial pneumonia in patients with connective tissue diseases.

Maze navigation by honeybees: learning path regularity

We investigated the ability of honeybees to learn mazes of four types: constant-turn mazes, in which the appropriate turn is always in the same direction in each decision chamber; zig-zag mazes, in which the appropriate turn is alternately left and right in successive decision chambers; irregular mazes, in which there is no readily apparent pattern to the turns; and variable irregular mazes, in which the bees were trained to learn several irregular mazes simultaneously. The bees were able to learn to navigate all four types of maze. Performance was best in the constant-turn mazes, somewhat poorer in the zig-zag mazes, poorer still in the irregular mazes, and poorest in the variable irregular mazes. These results demonstrate that bees do not navigate such mazes simply by memorizing the entire sequence of appropriate turns. Rather, performance in the various configurations depends on the existence of regularity in the structure of the maze and on the ease with which this regularity is recognized and learned.

[A case of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) related glomerulonephritis associated with systemic sclerosis treated by steroid pulse therapy: a case report]

A 57-year-old woman had been diagnosed as systemic sclerosis (SSc) with Raynaud's phenomenon, acrosclerosis and polyarthritis since 1995. She admitted to our hospital in July 1996 because of general fatigue, hemosputa and progressive renal insufficiency. On admission, the blood pressure was normal and laboratory findings showed elevation of the serum creatinin level and a high titer of the myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) (> 1000 EU). The renal biopsy revealed crescentic glomerulonephritis. Both renal insufficiency and high titers of MPO-ANCA improved remarkably after methylpredonisolone pulse therapy. This case was suggestive of elucidating the pathogenesis of SSc and MPO-ANCA related glomerulonephritis.

Gene structure and promoter for Crad2 encoding mouse cis-retinol/3alpha-hydroxysterol short-chain dehydrogenase isozyme

Cis-retinol/androgen dehydrogenase type 2 (CRAD2) has been shown to catalyze the dehydrogenation of retinols, including 9-cis retinol, and also to exhibit 3alpha- and 17beta- hydroxysteroid dehydrogenase activities. To examine the function of this enzyme and regulation of its gene, the Crad2 gene was cloned from a mouse genomic DNA library and characterized. The complete mouse CRAD2-coding region was found in four exons spanning an approximately 5kb region. The nucleotide sequences of the exons encoding 316 amino acids were identical to those of the previously reported mouse Crad2 cDNA. Primer extension analysis and RNase protection assay were used to map the major transcription initiation sites to the positions lying 87 and 89 base pairs upstream of the ATG translation start codon. The region proximal to the initiation sites exhibited the absence of both TATAA and CAAT boxes. This region had hepatocyte nuclear factor binding sites, consistent with its predominant expression in the liver. Computer analysis of an approximately 7.5kb 5'-flanking region also suggested the presence of binding sites for AP-1, SREBP1, HSF2, c-Rel, c-Myc, CREBP, GATA, Ets, E2F, and Oct-1, suggesting that various factors including retinoic acid, cholesterol, various kinds of stress, the cell cycle, and cyclic AMP may regulate the expression of this gene. Fluorescence in-situ hybridization analysis showed that Crad2 is located at the terminus of mouse chromosome 10, an area that corresponds to band 10D3, suggesting that RDH-related SDRs may be located together in the cluster locus. Northern blot hybridization and RT-PCR analysis demonstrated that CRAD2 was expressed not in early embryonic stages, and not in embryonic stem cells, but instead in the gastrointestinal tract during later embryonic development and adult stage. In conclusion, we have presented the first complete structural analysis, including that of the promoter and chromosomal location, of a member of the retinol/androgen dehydrogenase subfamily of the group of the short-chain dehydrogenase/reductase (SDR) isozymes. Our findings will provide the basis for in-vitro or in-vivo studies concerning the regulation of retinol and androgen metabolism and enable determination of the mechanism of diseases related to retinol, retinal, retinoic acid, and androgen.

Activated protein C reduces ischemia/reperfusion-induced renal injury in rats by inhibiting leukocyte activation

We examined whether activated protein C (APC) reduces ischemia/reperfusion (I/R)-induced renal injury by inhibiting leukocyte activation. In a rat model, intravenous administration of APC markedly reduced I/R-induced renal dysfunction and histological changes, whereas intravenous administration of dansyl glutamylglycylarginyl chloromethyl ketone-treated factor Xa (DEGR-FXa; active-site-blocked factor Xa), heparin or diisopropyl fluorophosphate-treated APC (DIP-APC; inactive derivative of ARC) had no effect. Furthermore, APC significantly inhibited the I/R-induced decrease in renal tissue blood flow and the increase in the vascular permeability, whereas neither DEGR-FXa, heparin, nor DIP-APC produced such effects. Renal I/R-induced increases in plasma levels of fibrin degradation products were significantly inhibited by APC, DEGR-FXa, and heparin. These observations suggest that APC reduces I/R-induced renal injury independently of its anticoagulant effects but in a manner dependent on its serine protease activity. Renal levels of tumor necrosis factor-alpha (TNF-alpha), rat interleukin-8, and myeloperoxidase were significantly increased after renal I/R. These increases were significantly inhibited by APC but not by DEGR-FXa, heparin, or DIP-APC. Leukocytopenia produced effects similar to those of APC. These findings strongly suggest that APC protects against I/R-induced renal injury not by inhibiting coagulation abnormalities but by inhibiting activation of leukocytes that play an important role in I/R-induced renal injury. Inhibition of leukocyte activation by APC could be explained by the inhibitory activity of TNF-alpha. (Blood. 2000;95:3781-3787)

SYNCRIP, a cytoplasmic counterpart of heterogeneous nuclear ribonucleoprotein R, interacts with ubiquitous synaptotagmin isoforms

Synaptotagmins (Syts) are a large family of membrane proteins consisted of at least 12 isoforms. They are categorized in neuron-specific isoforms (I-V, X, and XI) and ubiquitous isoforms (VI-IX) based on their expression patterns. Syt-I, a neuron-specific and abundant isoform, has been well characterized and postulated to be the exocytotic Ca(2+) sensor. However, the functions of other isoforms remain obscure. Here, we report that ubiquitous isoforms of synaptotagmins, Syt-VII, Syt-VIII, and Syt-IX, interacted with a cytoplasmic RNA-binding protein, SYNCRIP (Synaptotagmin-binding, cytoplasmic RNA-interacting protein), through their C2B domains. SYNCRIP was originally found in the Syt-II C2AB domain bound fraction from the mouse brain lysate. cDNA cloning of SYNCRIP cDNA revealed that the protein was highly homologous to heterogeneous nuclear ribonucleoprotein R (hnRNP R) recently identified. SYNCRIP protein was ubiquitously and constantly expressed in various tissues of mice parallel to hnRNP R. SYNCRIP indeed bound RNA with preference to poly(A) RNA; however, in contrast to the nuclear localization of hnRNP R, SYNCRIP was distributed predominantly in the cytoplasm as judged by both biochemical fractionation and immunohistochemical studies. In vitro binding experiments showed the potential interaction of SYNCRIP with C2B domains of Syts except for those of Syt-V, -VI, and -X. Furthermore, the interaction between SYNCRIP and Syt-VII, -VIII, or -IX was revealed by co-immunoprecipitation experiments using COS cells transiently expressing each Syt isoform. These findings suggested that SYNCRIP was a target of ubiquitous type of Syts and implied the involvement of ubiquitous Syts in the regulation of dynamics of the cytoplasmic mRNA.

Cupidin, an isoform of Homer/Vesl, interacts with the actin cytoskeleton and activated rho family small GTPases and is expressed in developing mouse cerebellar granule cells

A developmentally regulated Homer/Vesl isoform, Cupidin (Homer 2a/Vesl-2Delta11), was isolated from postnatal mouse cerebellum using a fluorescent differential display strategy. The strongest expression of Cupidin was detected in the cerebellar granule cells at approximately postnatal day 7. Cupidin was enriched in the postsynaptic density fraction, and its immunoreactivity was concentrated at glomeruli of the inner granular layer when active synaptogenesis occurred. Cupidin protein could be divided into two functional domains: the N-terminal portion, which was highly conserved among Homer/Vesl family proteins, and the C-terminal portion, which consisted of a putative coiled-coil structure, including several leucine zipper motifs. The N-terminal fragment of Cupidin, which was able to associate with metabotropic glutamate receptor 1 (mGluR1), also interacted with F-actin in vitro. In keeping with this, F-actin immunocytochemically colocalized with Cupidin in cultured cerebellar granule cells, and a Cupidin-mGluR1-actin complex was immunoprecipitated from crude cerebellar lysates using an anti-Cupidin antibody. On the other hand, the C-terminal portion of Cupidin bound to Cdc42, a member of Rho family small GTPases, in a GTP-dependent manner in vitro, and Cupidin functionally interacted with activated-Cdc42 in a heterologous expression system. Together, our findings indicate that Cupidin may serve as a postsynaptic scaffold protein that links mGluR signaling with actin cytoskeleton and Rho family proteins, perhaps during the dynamic phase of morphological changes that occur during synapse formation in cerebellar granule cells.

Molecular role of ascorbate in enhancement of NO production in activated macrophage-like cell line, J774.1

Ascorbate-enhanced nitric oxide (NO) production in lipopolysaccharide (LPS)- and interferon-gamma (IFN-gamma)-activated macrophage J774.1 cells through the inducible nitric oxide synthase (iNOS) pathway. The iNOS gene was synergistically induced by LPS and IFN-gamma. The inductive mechanism of ascorbate on the iNOS gene was studied by examining the degradation of I kappa B alpha by Western blotting, activation of the nuclear factor kappa B (NF-kappa B) by gel shift assays, and protein levels of interferon regulatory factor 1 (IRF-1) in LPS- and IFN-gamma-activated cells. Ascorbate had no effect on the onset of either I kappa B alpha degradation or the nuclear translocation of NF-kappa B, but it delayed the recovery of I kappa B alpha. The prolonged degradation of I kappa B alpha caused by ascorbate in LPS- and IFN-gamma-activated cells paralleled elevated NF-kappa B binding to DNA, which led to an increase in the iNOS protein level. Ascorbate alone did not induce I kappa B alpha degradation or NF-kappa B activation. Furthermore, ascorbate exerted no effect on the expression of I kappa B alpha and ubiquitin genes in the activated cells. Ascorbate could modulate NF-kappa B DNA binding activity in response to combined LPS and IFN-gamma activation, which increases NO production in activated macrophages.

Role of synaptotagmin, a Ca2+ and inositol polyphosphate binding protein, in neurotransmitter release and neurite outgrowth

Synaptotagmin I (or II), a possible Ca(2+)-sensor of synaptic vesicles, has two functionally distinct C2 domains: the C2A domain binds Ca2+ and the C2B domain binds inositol high polyphosphates (IP4, IP5, and IP6). Ca(2+)-regulated exocytosis of secretory vesicles is proposed to be activated by Ca2+ binding to the C2A domain and inhibited by inositol polyphosphate binding to the C2B domain. Synaptotagmins now constitute a large family and are thought to be involved in both regulated and constitutive vesicular trafficking. They are classified from their distribution as neuronal (synaptotagmin I-V, X, and XI) and the ubiquitous type (synaptotagmin VI-IX). Among them, synaptotagmins III, V, VI and X are deficient in IP4 binding activity due to the amino acid substitutions in the C-terminal region of the C2B domain, suggesting that these isoforms can work for vesicular trafficking even in the presence of inositol high polyphosphates. Synaptotagmin I is also known to be present in neuronal growth cone vesicles. Antibody against the C2A domain (anti-C2A) that inhibits Ca(2+)-regulated exocytosis also blocked neurite outgrowth of the chick dorsal root ganglion (DRG) neuron, suggesting that Ca(2+)-dependent synaptotagmin activation is also crucial for neurite outgrowth.