Typing for human platelet alloantigens

Antibodies to platelet alloantigens, and sometimes to isoantigens, induce severe clinical problems such as neonatal alloimmune thrombocytopenia (NAIT), post-transfusion purpura (PTP) and refractoriness to platelet transfusions (PTR). For example, NAIT affects approximately 1 in 5,000 live births. It is essential, therefore, to screen pregnant women for platelet antibodies in order to save babies' lives. Almost 40 years ago, two platelet alloantigen systems were discovered using relatively simple methods, namely the platelet agglutination test and the complement fixation test. However, these methods were not sensitive enough to identify all antibodies in mothers and patients, even in those with severe clinical problems. Tremendous effort has been devoted to establish more sensitive and reliable methods. In recent years, excellent new serological and immunochemical methods have been established and several new platelet antigen systems have been discovered. Simultaneously, newly developed molecular genetic techniques have been introduced for the typing and analysis of human platelet alloantigen systems. These methods allow DNA typing for cases in which serological typing is not available. In this article, the history of studies on human platelet alloantigen systems and isoantigens, the nomenclature of platelet alloantigen systems and their alleles, the present status of antibody detection and typing techniques and, finally, ethnic variations in platelet antigen profiles are reviewed.

(99m)Tc-HYNIC-derivatized ternary ligand complexes for (99m)Tc-labeled polypeptides with low in vivo protein binding

6-Hydrazinopyridine-3-carboxylic acid (HYNIC) is a representative agent used to prepare technetium-99m ((99m)Tc)-labeled polypeptides with tricine as a coligand. However, (99m)Tc-HYNIC-labeled polypeptides show delayed elimination rates of the radioactivity not only from the blood but also from nontarget tissues such as the liver and kidney. In this study, a preformed chelate of tetrafluorophenol (TFP) active ester of [(99m)Tc](HYNIC)(tricine)(benzoylpyridine: BP) ternary complex was synthesized to prepare (99m)Tc-labeled polypeptides with higher stability against exchange reactions with proteins in plasma and lysosomes using the Fab fragment of a monoclonal antibody and galactosyl-neoglycoalbumin (NGA) as model polypeptides. When incubated in plasma, [(99m)Tc](HYNIC-Fab)(tricine)(BP) showed significant reduction of the radioactivity in high molecular weight fractions compared with [(99m)Tc](HYNIC-Fab)(tricine)(2.) When injected into mice, [(99m)Tc](HYNIC-NGA)(tricine)(BP) was metabolized to [(99m)Tc](HYNIC-lysine)(tricine)(BP) in the liver with no radioactivity detected in protein-bound fractions in contrast to the observations with [(99m)Tc](HYNIC-NGA)(tricine)(2.) In addition, [(99m)Tc](HYNIC-NGA)(tricine)(BP) showed significantly faster elimination rates of the radioactivity from the liver as compared with [(99m)Tc](HYNIC-NGA)(tricine)(2.) Similar results were observed with (99m)Tc-labeled Fab fragments where [(99m)Tc](HYNIC-Fab)(tricine)(BP) exhibited significantly faster elimination rates of the radioactivity not only from the blood but also from the kidney. These findings indicated that conjugation of [(99m)Tc](HYNIC)(tricine)(BP) ternary ligand complex to polypeptides accelerated elimination rates of the radioactivity from the blood and nontarget tissues due to low binding of the [(99m)Tc](HYNIC)(tricine)(BP) complex with proteins in the blood and in the lysosomes. Such characteristics would render the TFP active ester of [(99m)Tc](HYNIC)(tricine)(BP) complex attractive as a radiolabeling reagent for targeted imaging.

Renal metabolism of 3'-iodohippuryl N(epsilon)-maleoyl-L-lysine (HML)-conjugated Fab fragments

Renal localization of radiolabeled antibody fragments constitutes a problem in targeted imaging and radiotherapy. Recently, we reported use of a novel radioiodination reagent, 3'-[131I]iodohippuryl N(epsilon)-maleoyl-L-lysine (HML), that liberates m-iodohippuric acid before antibody fragments are incorporated into renal cells. In mice, HML-conjugated Fab demonstrated low renal radioactivity levels from early postinjection times. In this study, renal metabolism of HML-conjugated Fab fragments prepared by different thiolation chemistries and by direct radioiodination were investigated to determine the mechanisms responsible for the low renal radioactivity levels. Fab fragments were thiolated by 2-iminothiolane modification or by reduction of disulfide bonds in the Fab fragments, followed by conjugation with radioiodinated HML to prepare [131I]HML-IT-Fab and [125I]HML-Fab, respectively. In biodistribution studies in mice, both [131I]HML-IT-Fab and [125I]HML-Fab demonstrated significantly lower renal radioactivity levels than those of [125I]Fab. In subcellular distribution studies, [125I]Fab showed migration of radioactivity from the membrane to the lysosomal fraction of the renal cells from 10 to 30 min postinjection. On the other hand, the majority of the radioactivity was detected only in the membrane fraction at the same time points after injection of both [131I]HML-IT-Fab and [125I]HML-Fab. In metabolic studies, while [125I]Fab remained intact at 10 min postinjection, both HML-conjugated Fab fragments generated m-iodohippuric acid as a radiometabolite at the same postinjection time. [131I]HML-IT-Fab registered two radiometabolites (intact [131I]HML-IT-Fab and m-iodohippuric acid), whereas additional radiometabolites were observed with [125I]HML-Fab. This suggested that metabolism of both HML-conjugated Fab fragments would occur in the membrane fractions of the renal cells. The findings of this study reinforced our previous hypothesis that radiochemical design of antibody fragments that liberate radiometabolites that are excreted into the urine by the action of brush border enzymes would constitute a useful strategy to reduce renal radioactivity levels from early postinjection times.

Interleukin-6 (IL-6) producing phaeochromocytoma: direct IL-6 suppression by non-steroidal anti-inflammatory drugs

A 35-year-old Japanese woman presented with a phaeochromocytoma and demonstrated marked inflammatory reactions and pyrexia as a result of excessive production of interleukin-6 (IL-6) by the tumour. Serum IL-6 level was 262 ng/l (normal; < 4.0 ng/l). Fever and inflammatory markers were largely overcome by the administration of the nonsteroidal anti-inflammatory drug, naproxen, and all symptoms disappeared soon after the tumour was excised. Immunohistochemical study revealed positive staining using an antihuman IL-6 antibody and Northern analysis showed increased IL-6 mRNA levels in the tumour. Cultured tumour cells showed IL-6 protein synthesis, and nonsteroidal anti-inflammatory drugs such as naproxen and indomethacin directly inhibited IL-6 release. These results indicate that the effects of naproxen in vivo were due, at least in part, to direct suppression of IL-6 secretion from the tumour.

Losartan and fetal toxic effects

We report a case of maternal exposure to the antihypertensive drug losartan during weeks 20-31 of pregnancy. We saw the fetal toxic effects of oligohydramnios (decreased amniotic fluid), fetal pulmonary hypoplasia, fetal hypoplastic skull bones, and subsequent fetal death. This pattern of abnormalities is similar to those seen in exposure to angiotensin-converting-enzyme (ACE) inhibitors during pregnancy, and were probably caused by losartan.

Plasma protein binding of (99m)Tc-labeled hydrazino nicotinamide derivatized polypeptides and peptides

6-Hydrazinopyridine-3-carboxylic acid (HYNIC) constitutes one of the most attractive reagents to prepare (99m)Tc-labeled polypeptides and peptides of various molecular weights in combination with two tricine molecules as coligands. Indeed, (99m)Tc-HYNIC-conjugated IgG showed biodistribution of radioactivity similar to that of (111)In-DTPA-conjugated IgG. However, recent studies indicated significant plasma protein binding when the (99m)Tc labeling procedure was expanded to low molecular weight peptides. In this study, pharmacokinetics of (99m)Tc-HYNIC-conjugated IgG, Fab and RC160 using tricine were compared with their radioiodinated counterparts to evaluate this (99m)Tc-labeling method. In mice, [(99m)Tc](HYNIC-IgG)(tricine)(2) and [(99m)Tc](HYNIC-Fab)(tricine)(2) showed persistent localization of radioactivity in tissues when compared with their (125)I-labeled counterparts. [(99m)Tc](HYNIC-IgG)(tricine)(2) eliminated from the blood at a rate similar to that of (125)I-labeled IgG, while [(99m)Tc](HYNIC-Fab)(tricine)(2) showed significantly slower clearance of the radioactivity than (125)I-labeled Fab. On size-exclusion HPLC analyses, little changes were observed in radiochromatograms after incubation of [(99m)Tc](HYNIC-IgG)(tricine)(2) in murine plasma. However, [(99m)Tc](HYNIC-Fab)(tricine)(2) and [(99m)Tc](HYNIC-RC160)(tricine)(2) demonstrated significant increases in the radioactivity in higher molecular weight fractions in plasma. Formation of higher molecular weight species was reduced when [(99m)Tc](HYNIC-RC160)(tricine)(2) was stabilized with nicotinic acid (NIC) to generate [(99m)Tc](HYNIC-RC160)(tricine)(NIC). [(99m)Tc](HYNIC-RC160)(tricine)(NIC) also demonstrated significantly faster clearance of the radioactivity from the blood than [(99m)Tc](HYNIC-RC160)(tricine)(2). These findings suggested that one of the tricine coligands in (99m)Tc-HYNIC-labeled (poly)peptides would be replaced with plasma proteins to generate higher molecular weight species that exhibit slow blood clearance. In addition, the molecular sizes of parental peptides played an important role in the progression of the exchange reaction of one of the tricine coligands with plasma proteins.

Significance of macrophage chemoattractant protein-1 in macrophage recruitment, angiogenesis, and survival in human breast cancer

Tumor cells stimulate the formation of stroma that secretes various mediators pivotal for tumor growth, including growth factors, cytokines, and proteases. However, little is known about the local regulation of these soluble mediators in the human tumor microenvironment. In this study, the local expression of cytokines, chemokines, and angiogenic factors was investigated in primary breast cancer tissue. The concentrations of interleukin (IL)-1, IL-4, IL-6, IL-10, IL-12, tumor necrosis factor (TNF)-alpha, IFN-gamma, IL-8, macrophage chemoattractant protein (MCP)-1, epithelial-neutrophil activating peptide-78, vascular endothelial growth factor, and thymidine phosphorylase (TP) were measured in 151 primary breast cancer extracts by ELISA. Tumor-associated macrophages (TAMs) were also examined by immunohistochemistry with anti-CD68 antibodies. The correlation between soluble mediators and the relationship between TAM count and soluble mediators were evaluated. MCP-1 concentration was correlated significantly with the level of vascular endothelial growth factor, TP, TNF-alpha, and IL-8, which are potent angiogenic factors. IL-4 concentration was correlated significantly with IL-8 and IL-10. On the other hand, an inverse association was observed between TP and IL-12. The level of MCP-1 was associated significantly with TAM accumulation. In the immunohistochemical analysis, MCP-1 expression was observed in both infiltrating macrophages and tumor cells. Prognostic analysis revealed that high expression of MCP-1, as well as of VEGF, was a significant indicator of early relapse. These findings indicate that interaction between the immune network system and angiogenesis is important for progression of human breast cancer, and that MCP-1 may play an important role in the regulation of angiogenesis and the immune system.

Tumor necrosis factor, tumor necrosis factor receptors type 1 and 2, lymphotoxin-alpha, and HLA-DRB1 gene polymorphisms in human T-cell lymphotropic virus type I associated myelopathy

We studied tumor necrosis factor (TNF), lymphotoxin-alpha (LT-alpha), and TNF receptors type 1 (TNFR-1) and type 2 (TNFR-2) gene polymorphisms as well as HLA class II DRB1 alleles in Japanese patients with human T-cell lymphotropic virus type I (HTLV-I) associated myelopathy (HAM) (n = 51), patients with adult T-cell leukemia/lymphoma (ATL) (n = 48), asymptomatic HTLV-I carriers (n = 50), and HTLV-I seronegative, normal controls (n = 112). There were significant differences between HAM patients and normal controls in the distributions of TNF promoter region polymophism at position --857, the LT-alpha gene NcoI polymorphism, and the T-G substitution in exon 6 of the TNFR-2 gene. The distribution of the NcoI polymorphism of the LT-alpha gene was also significantly different between HAM patients and asymptomatic HTLV-I carriers. In contrast, we failed to detect any difference in the frequency of DRB1, TNF promoter at position --1031, --863, or the TNFR-1 promoter --383 polymorphism. The results suggest that the TNF/LT-alpha gene region within the HLA class III of chromosome 6 and the TNFR-2 gene region located on chromosome 1p36 might contribute to susceptibility to HAM, and that aberrant expression or function of these cytokines and the receptor could be involved in the development of HAM.

Mechanisms of [2,3-butanedione bis(N4-dimethylthiosemicarbazone)]zinc (Zn-ATSM2)-induced protection of cultured hippocampal neurons against N-methyl-D-aspartate receptor-mediated glutamate cytotoxicity

Hyperexcitation of glutamatergic neurons may play a key role in ischemia-related neurodegeneration. Recent studies have suggested that the zinc ion (Zn2+), which is present in the central nervous system, has a modulatory role in glutamatergic neuron activity. Zinc ions block glutamate-induced depolarizing currents and neuronal damage by binding with zinc sites on the NMDA subtypes. Therefore, we examined the usefulness of zinc as a therapeutic agent for the prevention of ischemic neuronal damage in the brain. In our previous study, 2,3-butanedione bis(N4-dimethylthiosemicarbazonato) zinc complex (Zn-ATSM2), with high brain uptake, showed significant neuroprotective effects against cerebral ischemia in rats when administered systemically. In this study, to elucidate the mechanism of the neuroprotective effect of Zn-ATSM2, we first examined its in vitro protective effects against glutamate-, NMDA- and kainite-induced neurotoxicity in primary cultures of hippocampal neurons. Zn-ATSM2 elicited protective effects against this glutamate- and NMDA-induced neurotoxicity, but did not affect kainite-induced cytotoxicity. In addition, we studied the effects of Zn-ATSM2 on influx of Ca2+, which undergoes modification subsequent to NMDA activation. Zn-ATSM2 significantly decreased glutamate-induced 45Ca2+ uptake. Thus, Zn-ATSM2 protected against glutamate-induced neurotoxicity and its protective effect was, at least in part, due to the blockage of NMDA receptor-mediated Ca2+ influx.

Protective effect of FK506 in the reperfusion model after short-term occlusion of middle cerebral artery in the rat: assessment by autoradiography using [125I]PK-11195

The protective effect of the immunosuppressant agent FK506 in the reperfusion after short-term occlusion of the middle cerebral artery in the rat model was evaluated using [125I]PK-11195 autoradiography. FK506 0.5 mg kg-1 day-1 was administered intramurally to Wistar rats weighing 260-300 g from one day prior to ischemia to seven days after ischemia. Reperfusion was performed after 30 or 60 min occlusion. Infarct area was evaluated by [125I]PK-11195 autoradiography on the seventh day following occlusion. FK506 significantly reduced the infarct area in the caudate nucleus following 30 and 60 min occlusion, but significantly reduced the infarct area in the cortex only following 60 min occlusion. These results suggest that FK506 has a protective effect against reperfusion after short-term occlusion of the middle cerebral artery.

Different expression patterns of Bcl-2 family genes in breast cancer by estrogen receptor status with special reference to pro-apoptotic Bak gene

Oncogenic and anti-apoptotic Bcl-2 is expressed much less in estrogen receptor alpha (ERalpha) negative breast cancers, which show more malignant phenotypes, than ERalpha-positive, indicating that some other Bcl-2 family member(s) are involved in the apoptotic balance of the cancer cells. We first analyzed mRNA expression of pro-apoptotic Bak and Bax along with that of anti-apoptotic Bcl-2 and Bcl-xL, using breast cancer specimens of 27 patients. Bak mRNA was expressed much less in ERalpha negative breast cancers, along with reduced expression of Bcl-2. Immunostaining of sections of 108 patients confirmed the observation. Next, stable transformants of MCF-7 cells with sense Bak expression vector showed fewer colonies in soft agar compared with the parental cells, while stable introduction of antisense Bak vector enhanced colony formation at lower estradiol concentrations. The reduction of Bak may play important roles in malignant development of breast cancer to acquire estrogen independency, counteracting the reduced Bcl-2.

Association between type 1 diabetes age-at-onset and intercellular adhesion molecule-1 (ICAM-1) gene polymorphism

We investigated the intercellular adhesion molecule-1 (ICAM-1) gene polymorphism in 90 patients with young-onset type 1 diabetes, 74 with adult-onset type 1 diabetes, and 171 control subjects. The distribution of C-T genotypes and allele frequencies in exon 6 of the ICAM-1 gene was significantly different between adult-onset type 1 diabetes patients and controls (chi(2) = 9.76, p = 0.0076), and between patients with adult-onset and young-onset type 1 diabetes (chi(2) = 11.28, p = 0.0036). In contrast, we failed to detect any association between patients with young-onset type 1 diabetes and controls. Our data suggest that ICAM-1 exon 6 gene polymorphism affects the age-at-onset of type 1 diabetes and that different pathogenetic mechanisms may exist between young-onset and adult-onset type 1 diabetes.

The development of (99m)Tc-analog of Cu-DTS as an agent for imaging hypoxia

Works on dithiosemicarbazone (DTS) derivatives radiolabeled with divalent Cu (Cu-62, Cu-64) indicate its potentiality as an ischemic tissue detecting agent. Development of analogous derivatives labeled with the more accessible technetium-99m (Tc) is most desirable. Various synthesized DTS derivatives are radiolabeled with a novel approach, using a macromolecular Sn(II)-complex under an anaerobic condition at pH 3.4-4.5 and stabilization by ascorbate solution at pH 6.7-7.0. Characterization of Tc-DTS derivatives done by various analytical methods (TLC, HPLC, EP, PC) and by in vivo studies in normal mice and in rats myocardial LAD (left anterior descent coronary artery) occlusion model. Among tested DTS, only Tc-ATSE, Tc-ATSM and Tc-ATSM(2) showed distinctive characteristics, with the latter presenting high myocardium uptake in regions of ischemia in LAD rat myocardium model. Potentiality of the Cu-DTS mimetic agent, Tc-ATSM(2) as an ischemia-damaged myocardium agent is discussed.

Targeted delivery of radiolabeled imaging and therapeutic agents: bifunctional radiopharmaceuticals

Clinical application of radioactive diagnostic and therapeutic agents constitutes one of the great advances in noninvasive medicine, nuclear medicine. The radioactive agents used in the nuclear medical field are called "radiopharmaceuticals," and are required to exhibit high and specific localization of radioactivity into target tissue. Among radionuclides used in radiopharmaceuticals, radiometals such as 99mTc and (111)In have received much attention because of their nuclear physical characteristics and widespread availability. However, since these metallic elements are not constituents of bioactive molecules, they cannot simply replace common constituent atoms in biologically interesting compounds. Thus, demand for biospecific radiopharmaceuticals constitutes a great challenge in rational design of biologically active molecules labeled with metallic radionuclides, and evolves into a generation of bifunctional radiopharmaceuticals. Molecules contain both a biologically active site and a chelating group for binding the metallic radionuclide in which attachment of a chelating group does not affect the inherent biospecificity of the mother compound. This paper describes recent progress in research of macro- and small-molecular bifunctional radiopharmaceuticals for targeted diagnosis and therapy.

Human cytotoxic T-lymphocyte responses specific for peptides of the wild-type Wilms' tumor gene (WT1 ) product

The product of the Wilms' tumor gene WT1 is a transcription factor overexpressed not only in leukemic blast cells of almost all patients with acute myeloid leukemia, acute lymphoid leukemia, and chronic myeloid leukemia, but also in various types of solid tumor cells. Thus, it is suggested that the WT1 gene plays an important role in both leukemogenesis and tumorigenesis. Here we tested the potential of WT1 to serve as a target for immunotherapy against leukemia and solid tumors. Four 9-mer WT1 peptides that contain HLA-A2.1-binding anchor motifs were synthesized. Two of them, Db126 and WH187, were determined to bind to HLA-A2.1 molecules in a binding assay using transporter associated with antigen processing-deficient T2 cells. Peripheral blood mononuclear cells from an HLA-A2.1-positive healthy donor were repeatedly sensitized in vitro with T2 cells pulsed with each of these two WT1 peptides, and CD8(+) cytotoxic T lymphocytes (CTLs) that specifically lyse WT1 peptide-pulsed T2 cells in an HLA-A2.1-restricted fashion were induced. The CTLs also exerted specific lysis against WT1-expressing, HLA-A2.1-positive leukemia cells, but not against WT1-expressing, HLA-A2.1-negative leukemia cells, or WT1-nonexpressing, HLA-A2. 1-positive B-lymphoblastoid cells. These data provide the first evidence of human CTL responses specific for the WT1 peptides, and provide a rationale for developing WT1 peptide-based adoptive T-cell therapy and vaccination against leukemia and solid tumors.

Effect of chronic (-)-nicotine treatment on rat cerebral benzodiazepine receptors

The purpose of this study was to clarify the effect of (-)-nicotine on cerebral benzodiazepine receptors (BzR) with radiotracer methods. The effect of (-)-nicotine on BzR was examined in in vitro studies using chronic (-)-nicotine-treated rats using 3H-diazepam. The in vitro radioreceptor assay showed a 14% increase in the maximum number of binding sites of BzR in chronic (-)-nicotine-treated rats in comparison with the control rats. Moreover, a convenient in vivo uptake index of 125I-iomazenil was calculated and a higher uptake of the radioactivity was observed in the chronic (-)-nicotine-treated group than in the control group. Although further studies of the mechanism of (-)-nicotine on such BzR changes are required, an increase in the amount of BzR in the cerebral cortex was found in rats that underwent chronic (-)-nicotine treatment, and this result contributed to the understanding of the effects of (-)-nicotine and smoking on neural functions.

Evaluation of radioiodinated medium chain fatty acids as new diagnostic agents for the determination of hepatic viability

Radiopharmaceuticals which reflect beta-oxidation in hepatocytes will provide useful information on the prognosis after surgery or on the efficacy of treatment, since beta-oxidation is the main pathway responsible for adenosine triphosphate in hepatocytes. We have previously developed [1-11C]octanoate as a diagnostic agent for determination of hepatic viability by means of positron emission tomography (PET). The goal of the present study was to develop a new radiopharmaceutical for single-photon emission tomography (SPET), which has the advantage of being more widely used than PET. To this end, two radioiodinated omega-(4-iodophenyl)-medium chain fatty acids, p-iodophenylvaleric acid (IPVA) and p-iodophenylenanthic acid (IPEA), were synthesized and evaluated as radiopharmaceuticals for determination of hepatic viability. Metabolite analyses in vitro and in vivo and a biodistribution study in normal mice indicated that both compounds were taken up by the liver actively and metabolized by beta-oxidation. However, these studies also indicated that IPEA is more suitable as an imaging agent than IPVA. Based on these results, SPET imaging studies were performed in normal and hepatitis model rats using [123I]IPEA. The time-activity curves of the liver showed two-phase clearance of radioactivity in both normal and hepatitis model rats, but the clearance was delayed depending on the severity of hepatitis. Furthermore, the clearance rate of the first phase was correlated with the ATP level in hepatocytes, which was used as an index of the energy production capacity of hepatocytes. In conclusion, IPEA was metabolized predominantly by beta-oxidation, and the clearance of IPEA from the liver was closely associated with the ATP concentration in the liver. Thus, [123I]IPEA is a potentially useful new radiopharmaceutical for diagnosis of hepatic viability based on energy metabolism.

Endogenous interleukin-12: relationship with angiogenic factors, hormone receptors and nodal status in human breast carcinoma

Interleukin-12 (IL-12) is known to be a key cytokine for regulating immune response, but it is also known to provide some other biological function including inhibition of angiogenesis. We have determined using an enzymatic immunoassay the endogenous levels of IL-12 in 390 cytosols of primary breast cancers previously tested also for the angiogenic peptides, vascular endothelial growth factor (VEGF) and thymidine phosphorylase (TP). The concentration of IL-12 ranged from 0 to 7.6 ng/mg protein, and 124 (31.8%) out of 390 cancers showed a detectable dose (>0.1 ng/ml). There was no statistical association of IL-12 levels with tumor size and menopausal status. IL-12 levels tended to be higher in the tumors of node-positive patients as compared to those of node-negative ones (t-test, p=0.082). In addition, IL-12 levels were inversely associated with hormone receptor status, particularly progesterone receptor expression (p=0.0013). There was a significant inverse association between IL-12 and TP concentration (p=0.0007). The proportion of tumors with detectable levels of IL-12 and low levels of either VEGF or TP was higher among the patients with node-negative as compared to those with node-positive disease. On the contrary, the proportion of tumors with no detectable IL-12 and high levels of either VEGF or TP was higher in node-positive versus node-negative cancers. In conclusion, our study evaluated the balance between pro-angiogenic factors (TP and VEGF) and IL-12, as a detectable naturally occurring inhibitor of angiogenesis, in the same series of node-negative and node-positive breast cancers. Further studies are warranted to investigate the biological and clinical significance of the co-determination of pro and contra angiogenic factors in human breast carcinoma.

The integrity of the disulfide bond in a cyclic somatostatin analog during 99mTc complexation reactions

Recent development of a variety of thiol-free chelating agents has facilitated the design of 99mTc-labeled somatostatin analogs suitable for receptor imaging of somatostatin-positive tumors. However, it remains ambiguous whether the disulfide bonds in cyclic peptides are stable during 99mTc complexation reactions, and contradictory results have been reported regarding the integrity of disulfide bonds in cyclic somatostatin analogs. To estimate the stability of the disulfide bond in a synthetic somatostatin analog at low peptide concentrations, [125I]I-RC-160, in which radioiodine was incorporated into the 3-Tyr residue, was synthesized and the integrity of the disulfide bond of the peptide was investigated in the presence of reducing agents such as ascorbic acid, dithionite, and stannous ions. The disulfide bond in [125I]I-RC-160 remained stable in the presence of ascorbic acid in boiling water. The disulfide bond was also stable when treated with stannous ions at concentrations sufficient to reduce 99mTc for complexation with a thiol-free chelating agent, bis(hydroxamamide) analog when the 99mTc complexation reaction was performed at room temperature. However, the disulfide bond of [125I]I-RC-160 was slightly cleaved in the presence of a small amount of stannous ions when the reaction was performed in boiling water. Treatment of [125I]I-RC-160 with dithionite in boiling water markedly reduced the disulfide bond of the parental peptide. These findings indicated that synthetic somatostatin analogs may be labeled with 99mTc with stannous ions as the reducing agent without impairing their structure after conjugation of thiol-free chelating agents that provide 99mTc chelates under mild reaction conditions.

Carrier effect on radiolabeling the polynuclear pentavalent rhenium-186 complex of dimercaptosuccinic acid at alkaline pH: 186Re(V)-DMS

Radiolabeling with rhenium (Re-186, Re-188), a tumor agent to resemble the pentavalent polynuclear technetium complex of dimercaptosuccinic acid (99mTc[V]-DMS) has been reported for radiotherapeutical use. Nevertheless, despite the periodic analogies between both radiometals, differences in the redox potential and the carrier concentration have made the radiolabeling of the rhenium counterpart difficult. In the present study, the effect of the carrier contained in the reactor-produced Re-186 was estimated as an important factor relevant to the Re-186 radiolabeling of DMS at an alkaline pH. Great effect of the carrier Re with an inverse correlation with the stannous ion was an interesting phenomenon relevant for an assumption on the Sn participation in the complex. Under strict control of various labeling parameters, the 186Re(V)-DMS was made available with high yield (93-97%) at an alkaline pH and at room temperature. The great effect of carrier offers support to the polymeric or polynuclear nature of the rhenium complex of DMS as depicted in the drug design basis of its parent Tc(V)-DMS. The biodistribution studies of Re(V)-DMS showed mimetic characteristics with its parent Tc(V)-DMS drug.

Influence of TNF microsatellite polymorphisms (TNFa) on age-at-onset of insulin-dependent diabetes mellitus

The TNF-alpha gene is located in the HLA region and has been implicated in the pathogenesis of Type I (insulin-dependent) diabetes mellitus (IDDM). We investigated the frequency of TNFa microsatellite alleles in 76 young-onset IDDM patients, 65 adult-onset IDDM patients, and 90 control subjects. We also examined the association of these TNFa alleles with HLA-DRB1 alleles, HLA-class I alleles, and TNF-alpha production. The frequency of the TNFa2 and TNFa9 alleles was increased in the young-onset IDDM patients compared to control subjects, but the increased frequency of TNFa2 was not significant after the correction for the number of comparisons was made. We did not find any association of TNFa2 or TNFa9 with any of the HLA-DRB1 alleles. In contrast, the frequency of the TNFa13 allele was decreased in both the young-onset and the adult-onset IDDM patients compared to the control subjects, but the difference lost significance after the correction was made in the adult-onset IDDM. The TNFa13 allele was strongly associated with DRB1*1502. Patients with TNFa2 or TNFa9 had greater TNF-alpha production, while those positive for TNFa13 had lower TNF-alpha production than patients with non-TNFa2, a9, and a13 alleles. These results suggest that TNFa polymorphisms are associated with age-at-onset of IDDM and influence the inflammatory process of pancreatic beta cell destruction in the development of IDDM.

HLA antigens in patients with variant angina in Japan

There have been few reports on examining the susceptibility of variant angina. Accordingly, the major histocompatibility complexes (HLA-A, -B, -C, -DR) of unrelated Japanese patients with variant angina were examined. There were no significant differences in the frequency of HLA-A,-B, -C, and -DR antigens between patients and controls (n = 100). Although endothelial dysfunction with pathological abnormalities is suggested to be one of the etiological factors in vasospasm, immunogenetic abnormalities linked to HLA system might not play a role in the pathogenesis of variant angina.

Pharmacokinetic analysis of 123I-labeled medium chain fatty acid as a radiopharmaceutical for hepatic function based on beta-oxidation

Beta-oxidation is the most important pathway to provide energy for the liver. Our recent findings indicated that radiolabeled medium chain fatty acid analogs could be used as radiopharmaceuticals in the liver, allowing us to monitor alterations in energy metabolism on the cellular level. In the present study, pharmacokinetical analysis of a radioiodinated medium chain fatty acid analog, 6-[123I]iodophenylenanthic acid ([123I]IPEA), was carried out in normal and hepatitis model rats to investigate the index for the measurement of beta-oxidation activity in hepatocytes. The rate constant for metabolism of [123I]IPEA in the liver showed a strong correlation with the ATP level, which was determined as an indicator of beta-oxidation activity in hepatocytes. The radioactivity profile in the liver after [123I]IPEA administration provided important information regarding hepatic viability, and the metabolic rate constant of [123I]IPEA calculated by a pharmacokinetic method was a useful criterion for hepatic diagnosis based on hepatic cellular energy metabolism.

A novel immunoscintigraphy technique using metabolizable linker with angiotensin II treatment

Immunoscintigraphy is a tumour imaging technique that can have specificity, but high background radioactivity makes it difficult to obtain tumour imaging soon after the injection of radioconjugate. The aim of this study is to see whether clear tumour images can be obtained soon after injection of a radiolabelled reagent using a new linker with antibody fragments (Fab), in conditions of induced hypertension in mice. Fab fragments of a murine monoclonal antibody against human osteosarcoma were labelled with radioiodinated 3′-iodohippuryl N-ɛ-maleoyl-L-lysine (HML) and were injected intravenously to tumour-bearing mice. Angiotensin II was administered for 4 h before and for 1 h after the injection of radiolabelled Fab. Kidney uptake of ¹²⁵I-labelled-HML-Fab was much lower than that of ¹²⁵I-labelled-Fab radioiodinated by the chloramine-T method, and the radioactivity of tumour was increased approximately two-fold by angiotensin II treatment at 3 h after injection, indicating high tumour-to-normal tissue ratios. A clear tumour image was obtained with ¹³¹I-labelled-HML-Fab at 3 h post-injection. The use of HML as a radiolabelling reagent, combined with angiotensin II treatment, efficiently improved tumour targeting and enabled the imaging of tumours. These results suggest the feasibility of PET scan using antibody fragment labelled with ¹⁸F-fluorine substitute for radioiodine. © 1999 Cancer Research Campaign