Association of a new allele of the TAP2 gene, TAP2*Bky2 (Val577), with susceptibility to Sjögren's syndrome

OBJECTIVE

To investigate the polymorphisms of TAP (transporters associated with antigen processing) genes among patients with primary Sjögren's syndrome (SS) in order to clarify the potential association of the polymorphisms with disease susceptibility.

METHODS

Polymorphisms of the TAP1 and TAP2 genes in 108 Japanese SS patients were determined by analyzing TAP genes using the polymerase chain reaction-single-stranded conformation polymorphism technique.

RESULTS

The allelic frequency of the TAP1 gene was not significantly different between SS patients and normal subjects. In addition to all known TAP2 alleles, a new allele (Bky2), which had a unique substitution at codon 577 (ATG-->GTG: Met-->Val), was identified in both groups. The allelic frequency of Bky2 was significantly higher in SS patients (12.0%) than in normal subjects (5.1%) (P < 0.05). Moreover, a significantly greater frequency of SS-A antibody was found among SS patients with Bky2 (18 of 23; 78%) than among those without Bky2 (33 of 85; 39%) (P = 0.001).

CONCLUSION

The mutation in TAP2 (Val577) may be involved in SS-A autoantibody production and could be a genetic factor that determines susceptibility to SS.

A novel radioiodination reagent for protein radiopharmaceuticals with L-lysine as a plasma-stable metabolizable linkage to liberate m-iodohippuric acid after lysosomal proteolysis

Radiochemical design of polypeptides using metabolizable linkages would be attractive to enhance target-selective localization of radioactivity for diagnostic and therapeutic nuclear medicine. However, while use of ester bonds as the linkage allows selective release of the designed radiometabolite from covalently conjugated polypeptides after lysosomal proteolysis in nontarget tissues, low plasma stability of ester bonds causes a decrease in radioactivity levels of the target. In pursuit of new metabolizable linkages that provide stable attachment of radiolabels with polypeptide in plasma while facilitating rapid and selective release of designed radiometabolites of rapid urinary excretion in lysosomes, a new radioiodination reagent with L-lysine as the metabolizable linkage to liberate m-iodohippuric acid (L-HML) was designed and synthesized. Stabilities of the metabolizable linkage in serum and cleavabilities of the linkage in lysosomal proteolysis in hepatic cells were investigated after conjugation of [131I]-L-HML with galactosyl-neoglycoalbumin (NGA). For comparison, a radioiodination reagent with an ester bond to release m-iodohippuric acid (MIH) was conjugated with NGA under similar conditions. When incubated in human serum, [131I]-L-HML-NGA liberated less than 3% of the initial radioactivity after 24 h, whereas [125I]MIH-NGA released more than 60% of its radioactivity during the same interval. In biodistribution studies, [131I]-L-HML-NGA demonstrated radioactivity elimination from murine liver at a rate and excretion route similar to [125I]MIH-NGA. Analyses of murine urine after injection of [131I]-L-HML-NGA indicated a single radioactivity peak at fractions identical to those of m-iodohippuric acid. Biodistribution studies of radioiodinated NGAs with D-lysine or cadaverine as the linkages demonstrated a delayed elimination rate from murine liver with significantly higher radioactivity being excreted in the feces at 24 h postinjection. Thus, L-HML is the first reagent that allows stable attachment of radiolabel with polypeptide in serum while facilitating selective release of a radiometabolite with rapid urinary excretion from covalently conjugated polypeptides after lysosomal proteolysis at a rate similar to that of ester bonds. Thus, L-HML is potentially useful for the radioiodination of polypeptides for diagnostic and therapeutic purposes.

Conventional and high-yield synthesis of DTPA-conjugated peptides: application of a monoreactive DTPA to DTPA-D-Phe1-octreotide synthesis

Successful imaging of somatostatin receptor-positive tumors with 111In-DTPA-D-Phe1-octreotide has stimulated development of peptide radiopharmaceuticals using DTPA as the chelating agent. However, use of cyclic DTPA dianhydride (cDTPA) resulted in low synthetic yields of DTPA-peptide by either solution or solid-phase syntheses. This paper reports a novel high-yield synthetic procedure for DTPA-D-Phe1-octreotide that is applicable to other peptides of interest using a monoreactive DTPA derivative. A monoreactive DTPA that possesses one free terminal carboxylic acid along with four carboxylates protected with tert-butyl ester (mDTPA) was synthesized. Fmoc-Thr(tBu)-ol, prepared from Fmoc-Thr(tBu)-OH, was loaded onto 2-chlorotrityl chloride resin. After construction of the peptide chains by Fmoc chemistry, mDTPA was coupled to the alpha amine group of the peptide on the resin in the presence of 1,3-diisopropylcarbodiimide and 1-hydroxybenzotriazole. Treatment of the mDTPA-peptide-resin with trifluoroacetic acid-thioanisole removed the protecting groups and liberated [Cys(Acm)2,7]-octreotide-D-Phe1-DTPA from the resin. Iodine oxidation of the DTPA-peptide, followed by the reversed-phase HPLC purification, produced DTPA-D-Phe1-octreotide in overall 31.8% yield based on the starting Fmoc-Thr(tBu)-ol-resin. The final product gave a single peak on analytical HPLC, and amino acid analysis and mass spectrometry confirmed the integrity of the product. 111In radiolabeling of the product provided 111In-DTPA-D-Phe1-octreotide with > 95% radiochemical yield, as confirmed by analytical reversed-phase HPLC, TLC, and CAE. These finding indicated that use of mDTPA during solid-phase peptide synthesis greatly increased the synthetic yield of DTPA-D-Phe1-octreotide, due to the absence of nonselective reactions that are unavoidable when cDTPA is used. These results also suggested that mDTPA would be a versatile reagent to introduce DTPA with high yield into peptides of interest.

The HLA system in the population of Mongolia

The frequencies of HLA-A, B, C and DRB1 alleles and haplotype frequencies for HLA-A, B, C and A, B, DR loci were studied in 201 healthy unrelated Khalkha-Mongolians. The most common class I antigens were A24 (25.8%), A2 (23.4%), B61 (12.6%), B51 (8.5%), Cw10 (14.2%), Cw9 (14.1%), Cw7 (13.3%), Cw1 (11.8%) and Cw6 (10.2%). A total of 35 DRB1 alleles were identified in this group of samples. The most frequent DRB1 allele was DRB1*0301 (11.1%), followed by DRB1*0701 (9.7%) and DRB1*1101 (8.5%). One novel DRB1 allele (14MV) and three rare types, DRB1*1111, DRB1*1504 and DRB1*1412, recently described in Jews, the Dai minority of China and Japanese, respectively, were identified in Mongolians. The phylogenetic tree constructed by UPG method put Mongolians in the Northeast Asian cluster. A comparison of three locus haplotype distributions with world populations, revealed that Mongolians share several characteristics in common with other Mongoloids as well as with Caucasoids and Amerindians. The most common A, B and DR haplotype in Mongolians, A33-B58-DR3, was shared with Thai, Thai Chinese and Singapore Chinese. These data support that unique genetic background of Mongolians played a major role in ethnic formation and differentiation of Mongoloid populations.

Gangliosides involved in activation of rat T lineage cells

Gangliosides have long been known to be involved in T-cell activation. In our previous studies, a unique GMlb-derived ganglioside, GD1c(NeuGc,NeuGc), was shown to be the predominant ganglioside in rat thymocytes and T-cells. Upon the activation of the thymocytes, the amount of GD1c(NeuGc,NeuGc) increases remarkably, and additionally a novel species of GD1b, GD1b(NeuGc,NeuGc), appears as the other major ganglioside (Nohara, et al. (1993) J. Biol. Chem. 268, 24997-25000). In the present study, monoclonal antibodies (MAbs) against these two gangliosides have been generated. The MAb AC1 established by immunizing mice with purified GD1c(NeuGc,NeuGc) reacted strongly with GD1c(NeuGc,NeuGc) and weakly with GD1b(NeuGc,NeuGc) by enzyme-linked immunosorbent assay (ELISA). The other MAb AB1 obtained by immunization with GD1b(NeuGc,NeuGc) showed a strong binding activity to GD1b(NeuGc,NeuGc) and no reactivity to GDlc(NeuGc,NeuGc) by ELISA. Flow cytometry analyses using these MAbs have revealed that an AC1-positive subset exists in a portion of resting CD4+CD8- thymocytes and CD4+ splenic T-cells. When the thymocytes were activated with 12-O-tetradecanoylpholbol-13-acetate (TPA) and calcium ionophore A23187, the proportion of AC1+ cells increased remarkably and were detected not only in CD4+ cells but also in CD8+ cells. An increase in the proportion of AC1+ cells was also seen in activated T-cells. In contrast, AB1-positive cells were only detected in activated thymocytes, not in resting thymocytes, or resting or activated T-cells. These results implicate GD1c(NeuGc,NeuGc) in the activation of thymocytes as well as T-cells, whereas GD1b(NeuGc,NeuGc) appears to be specifically related to the activation of thymocytes.

Synthesis and characterization of radioiodinated (S)-5-iodonicotine: a new ligand for potential imaging of brain nicotinic cholinergic receptors by single photon emission computed tomography

(S)-5-Iodonicotine (4a), an (S)-nicotine analog iodinated at the 5-position of the pyridine ring, was synthesized and evaluated as a potential radiopharmaceutical for investigating brain nicotine receptors by single photon emission computerized tomography (SPECT). [125I]-(S)-Iodonicotine ([125I]-4a) was synthesized by the iododestannylation reaction under no-carrier-added conditions and purified by high-performance liquid chromatography (HPLC). The binding affinity of 4a for brain nicotine receptors was measured in terms of displacement of [3H]cytisine from binding sites in rat cortical membranes. The binding data revealed that the affinity of 4a was the same as that of (S)-nicotine and 80-fold higher than that of the (R)-enantiomer (4b). Biodistribution studies in mice disclosed that the brain uptake of [125I]-4a was rapid and profound. Regional cerebral distribution studies in rats by autoradiography disclosed that the accumulation of [125I]-4a was dense in the thalamus, intermediate in the cortex and striatum, and less marked in the cerebellum. Furthermore, the administration of (S)-nicotine reduced the uptake of [125I]-4a in the thalamus and resulted in a nearly identical level of radioactivity in the cerebellum. [125I]-(R)-5-Iodonicotine ([125I]-4b) showed more rapid washout from the brain and a less extensive regional cerebral distribution than the (S)-enantiomer ([125I]-4a). Thus, 4a bound to brain nicotine receptor in vivo, and therefore iodine-123-labeled 4a may be a potential radioligand for use in vivo cerebral nicotinic receptor studies by SPECT.

Analysis of allelic variation of the TAP2 gene in sarcoidosis

Sarcoidosis is a systemic granulomatous disease and the DRB1 gene of the DR subregion has been implicated for determining the genetic susceptibility to the disease. We evaluated the allelic variation of the TAP2 gene using the PCR-RFLP method as well as the mismatched PCR-RFLP method in 82 Japanese patients with sarcoidosis and 92 healthy controls. A new allele, TAP2*0103 and a new polymorphic variation at codon 577 in addition to TAP2*0101, TAP2*0102 and TAP2*0201 have been recognized in the Japanese subjects. No significant differences were observed in the frequencies of any TAP2 alleles or dimorphism at codon 577 between the patients and healthy controls. Polymorphic variation of the TAP2 gene does not confer the susceptibility to sarcoidosis.

Allele typing of HLA-A10 group by nested-PCR-low ionic strength single stranded conformation polymorphism and a novel A26 allele (A26KY, A*2605)

HLA-A26 is one of the most polymorphic HLA-A locus antigens among the Japanese population. Four HLA-A26 subtypes have so far been defined: A*2601-2604 [1]. We developed a means of typing alleles of the HLA-A10 group by nested PCR low ionic strength single-stranded conformation polymorphism (NPCR-LIS-SSCP) that is simple and cost effective. We used it to type 200 DNA samples from unrelated Japanese individuals who were serologically HLA-A26 positive. We found a novel A26 allele that had been suggested by PCR-SSO. Sequence analysis of A26KY (officially assigned A*2605, Accession No. D50068) revealed that the allele differs from A*2601 by a single nucleotide substitution at position 299, which leads to an amino acid substitution Ala-->Glu at position 76 in the alpha helix loop of the alpha 1 domain. From our results, A*2605 is likely to originate from A*2601 by a single point mutation. HLA-A*2601 showed the highest frequency (61.9%), followed by A*2603 (19.5%), A*2602 (17.6%), A*2604 (0.5%), and A*2605 (0.5%) in Japanese.

Ginseng pretreatment protects against transient global cerebral ischemia in the rat: measurement of local cerebral glucose utilization by [14C]deoxyglucose autoradiography

The effect of ginseng on brain glucose metabolism has been determined in normal and transient cerebral ischemic rat using the autoradiographic [14C]2-deoxyglucose method. Ginseng had no effect on local cerebral glucose utilization (LCGU) in normal rat. By contrast, in rats subjected to 30 min of four vessel occlusion, a significant reduction of LCGU was shown in parts of the cortex and striatum in comparison to the control group. One-week administration of ginseng at 200 mg/kg/d before the occlusion produced an improvement of LCGU compared with the untreated group. These findings indicate that ginseng has some protective effects against brain damage in transient global cerebral ischemia.

Synthesis, in vitro binding profile and biodistribution of a 125I-labeled N-benzyl pyrrolidinyl benzamide derivative: a potential radioligand for mapping dopamine D2 receptors

cis-N-(1-Benzyl-2-methylpyrrolidine-3-yl)-5-iodo-2-methoxy-4-(methylamin o) benzamide (IYM), a YM-09151-2 analog iodinated at the 5-position of the benzoyl moiety, was synthesized and evaluated as a potential radiopharmaceutical for investigating brain dopamine D2 receptors by single photon emission computer tomography (SPECT). [125I]IYM was synthesized by a halogen exchange reaction and purified by high-performance liquid chromatography (HPLC). An in vitro competitive binding study with [3H]spiperone using rat striatal synaptosomal membranes revealed that IYM had higher affinity for dopamine D2 receptors than did YM-09151-2 or spiperone. In a saturation binding study using rat striatal synaptosomal membranes, IYM had a Kd of 0.04 nM. Biodistribution studies in mice disclosed that [125I]IYM exhibited high and specific striatal uptake, with the striatal/cerebellar uptake ratio being 14 at 120 min after injection. Furthermore, the striatal uptake of [125I]IYM was saturable, and [125I]IYM was displaced only by dopaminergic compounds. Ex vivo autoradiographic studies in rats further confirmed the high uptake and retention of this agent in the striatum and total blockade of its uptake by YM-09151-2. Thus, IYM showed specific binding to dopamine D2 receptors in the rodent striatum and therefore holds great potential for use in in vivo dopamine D2 receptor studies.

PCR-LIS-SSCP (Low ionic strength single-stranded conformation polymorphism)--a simple method for high-resolution allele typing of HLA-DRB1, -DQB1, and -DPB1

We have developed a simple and efficient procedure with which to form single-stranded DNA [ssDNA] and then applied HLA-DRB1, -DQB1, and -DPB1 allele typing. This method is referred to as low ionic strength single-stranded conformation polymorphism (LIS-SSCP), and is based on the diversity in the electrophoretic mobility of ssDNA formed by heat denaturation in low ionic strength solutions. This method detected DNA polymorphisms, including point mutations at a variety of positions in the DNA fragments of the HLA-DRB1, -DQB1, and -DPB1 genes. Under our experimental conditions, stable ssDNA could be kept at room temperature > or = 5 hr without having been cooled on ice immediately after heat denaturation. A total of 41 HLA-DRB1, 14 HLA-DQB1, and 17 HLA-DPB1 alleles from 220 healthy people were analyzed using a combination of PCR-LIS-SSCP with group-specific amplification. All of the alleles analyzed were discriminated among the DRB1, DQB1, and DPB1 groups except for DPB1*0402 and 0201. The efficiency of ssDNA formation using the LIS-SSCP procedure was higher than that of the traditional formamide method, and the SSCP profiles were clearer than those of the original SSCP. This procedure is useful for screening new alleles as well as the donor-recipient molecular matching of HLA class II genes. It is simple, rapid, and cost effective, requiring neither radioisotopes nor enzymes to confirm the typing results of other methods.

Paraquat tolerance of transgenic Nicotiana tabacum with enhanced activities of glutathione reductase and superoxide dismutase

Transgenic tobacco with enhanced cytosolic activities of glutathione reductase and superoxide dismutase were generated by cross-fertilization. Leaves of the hybrids exhibited further increased tolerance to a O2-.-generating herbicide paraquat than those of their parents. This result indicates the efficiency of manipulating more than one gene in improving resistance of plants to photooxidative stress.

Paraquat tolerance of transgenic Nicotiana tabacum with enhanced activities of glutathione reductase and superoxide dismutase

Transgenic tobacco with enhanced cytosolic activities of glutathione reductase and superoxide dismutase were generated by cross-fertilization. Leaves of the hybrids exhibited further increased tolerance to a O2-.-generating herbicide paraquat than those of their parents. This result indicates the efficiency of manipulating more than one gene in improving resistance of plants to photooxidative stress.

Expression of Arabidopsis cytosolic ascorbate peroxidase gene in response to ozone or sulfur dioxide

The effects of ozone or sulfur dioxide on antioxidant enzymes were investigated in Arabidopsis thaliana. Plants were fumigated with 0.1-0.15 ppm ozone or sulfur dioxide up to about 1 week in an environment-controlled chamber. Both pollutants increased the activities of ascorbate peroxidase and guaiacol peroxidase in leaves, but had little effect on the activities of superoxide dismutase, catalase, monodehydroascorbate reductase, dehydroascorbate reductase or glutathione reductase. Ozone was more effective than sulfur dioxide in increasing the activities of the peroxidases. Ascorbate peroxidase activity increased 1.8-fold without a lag period during fumigation with 0.1 ppm ozone, while guaiacol peroxidase activity increased 4.4-fold with a 1-day lag. Expression of the APX1 gene encoding cytosolic ascorbate peroxidase was further investigated. Its protein levels in leaves exposed to 0.1 ppm ozone for 4 or 8 days were 1.5-fold higher than in controls. Both ozone and sulfur dioxide elevated APX1 mRNA levels in leaves at 4 and 7 days, whereas at 1 day only ozone was effective. The induction of APX1 mRNA levels by ozone (3.4- to 4.1-fold) was more prominent than that by sulfur dioxide (1.6- to 2.6-fold). The APX1 mRNA level increased by day and decreased by night. Exposure of plants to 0.1 ppm ozone enhanced the APX1 mRNA level within 3 h, which showed a diurnal rhythm similar to that of the control. These results demonstrate that near-ambient concentrations of ozone as well as similar concentrations of sulfur dioxide can induce APX1 gene expression in A. thaliana.

Application of [125I] (S)-5-iodonicotine, a new radioiodinated ligand, in the assay of nicotinic acetylcholine receptor binding in the brain

[125I](S)-5-Iodonicotine was prepared and its application in the assay of nicotinic acetylcholine receptor binding in the brain was studied. [125I](S)-5-Iodonicotine bound to the rat cortical membrane with high affinity (Kd, 15.0 nm). Various nicotinic cholinergic compounds showed competition with [125I](S)-5-iodonicotine for the binding sites in the rats cortical membrane, and the specificity of its binding was correlated well with that of [H3] cytisine (r = 0.98). These findings suggest that [125I](S)-5-iodonicotine binds to the same sites as [H3] cytisine and indicate that [125I](S)-5-iodonicotine can be applied as a brain nicotine receptor binding assay.

Initial clinical experiences with dopamine D2 receptor imaging by means of 2'-iodospiperone and single-photon emission computed tomography

Dopamine D2 receptor imaging was performed with 123I labeled 2'-iodospiperone (2'-ISP) and single-photon emission computed tomography (SPECT) in 9 patients: 4 with idiopathic Parkinson's disease, 2 with parkinsonism, 1 with Wilson's disease and 2 with pituitary tumor, and the results were compared with the data for 9 normal subjects. Following an intravenous injection of 123I-2'-ISP, early (within 30 min) and late (between 2 and 4 hr) SPECT images were obtained by means of a multi-detector SPECT scanner or a rotating gamma camera. In normal subjects, early SPECT images demonstrated uniform distribution of radioactivity in the cerebral gray matter and cerebellum reflecting regional cerebral blood flow, whereas late SPECT images showed high radioactivity only in the basal ganglia. All the patients with Parkinson's disease also demonstrated symmetrical basal ganglia uptake in the late SPECT images, but it was diminished in parkinsonism and Wilson's disease. One patient with a growth hormone-producing pituitary tumor had a positive uptake in the tumor. These preliminary clinical data demonstrated that 2'-ISP can be used for SPECT imaging of D2 dopamine receptors and may be of clinical value for the diagnosis and planning of the treatment of neurological diseases.

Isolation of cDNA for a plasma membrane H(+)-ATPase from guard cells of Vicia faba L

cDNA encoding the plasma membrane H(+)-ATPase of guard cells of Vicia faba L. was isolated. The clone encoded a 105-kDa polypeptide (956 amino acids) that was 79-85% identical in terms of amino acid sequence to other plant H(+)-ATPases. High levels of mRNA explain the high H(+)-ATPase activity of these plasma membranes.

SPECT imaging of dopamine D2 receptors with 2'-iodospiperone

SPECT imaging of dopamine D2 receptors was performed using 123I-labeled 2'-iodospiperone (2'-ISP).

METHODS

Iodine-123-2'-ISP was administered to 12 normal subjects. Serial SPECT scans were obtained in six normal subjects for kinetic studies and static SPECT images were obtained in four normal subjects. Two additional normal subjects had serial whole-body imaging to calculate radiation dosimetry.

RESULTS

Serial SPECT scans demonstrated rapid initial brain uptake followed by gradual washout from the cerebral cortex and cerebellum, while the activity in the basal ganglia was stable for 2 hr and gradually decreased thereafter. There was fast clearance of blood activity with rapid conversion of 2'-ISP to the hydrophilic metabolites. The basal ganglia-to-frontal cortex ratio increased with time and plateaued between 2 and 4 hr postinjection. The basal ganglia-to-frontal cortex ratio obtained during this period demonstrated an age-dependent decrease similar to other D2 ligands.

CONCLUSION

2'-ISP can be used for mapping dopamine D2 receptors in human brain with SPECT. The relatively high background activity, however, suggests that further modification of the compound may be needed prior to widespread clinical use.

[125I]iomazenil binding in the brains of spontaneously epileptic rats: an ex vivo quantitative autoradiographic study

Central benzodiazepine receptor binding was studied in spontaneously epileptic rats (SER) and in their parent strain. Kyoto-Wistar (KW) rats, by ex vivo quantitative autoradiography with [125I]iomazenil. Thirteen-week-old SER developed tonic and absence-like seizures following mild stimulation by tapping at 5 min before injection of the radioligand. When compared with age-matched KW rats, a significant 76% elevation of radioactivity was observed in the SER hippocampus, while there was no difference in hippocampal blood flow obtained using [125I]N-isopropyl-p-iodoamphetamine. Since benzodiazepine receptors act to enhance inhibitory GABA transmission, this finding suggests a possible mechanism for seizure-induced enhancement of inhibition.

Noninvasive measurement of cerebral blood flow and glucose metabolic rate in the rat with high-resolution animal positron emission tomography (PET): a novel in vivo approach for assessing drug action in the brains of small animals

The cerebral metabolic rate of glucose (CMRglc) and cerebral blood flow (CBF) in rats were estimated noninvasively with a high-resolution animal positron emission tomography (PET) system that we recently developed. Qualifications of CMRglc and CBF were attempted with radiotracers, 18F-2-fluoro-2-deoxyglucose and 15O-water, respectively. From the data obtained with PET, the CMRglc and CBF values under pretreatment conditions were respectively calculated as 51 +/- 14 mumol/min/100 g and 61 +/- 7 ml/min/100 g under pentobarbital-anesthesia. These values were in close agreement with published data obtained with the autoradiographic technique. Moreover, an increase of 69% (mean) in CBF was detected after i.v. acetazolamide administration. The results indicate that this high-resolution animal PET scanner holds great potential for the assessment of drug-related metabolic and circulatory effects in intact and experimental animals.