Stability of a metabolizable ester bond in radioimmunoconjugates

Ester bonds have been used as metabolizable linkages to reduce radioactivity levels in non-target tissues following the administration of antibodies labeled with metallic radionuclides. In this radiochemical design of antibodies, while the ester bonds should be cleaved rapidly in non-target tissues, high stability of the ester bonds in plasma is also required to preserve target radioactivity levels. To assess the structural requirements to stabilize the ester bond, a new benzyl-EDTA-derived bifunctional chelating agent with an ester bond, (1-[4-[4-(2- maleimidoethoxy)succinamido]benzyl]ethylenediamine-N,N,N',N' -tetraacetic acid; MESS-Bz-EDTA), was developed. MESS-Bz-EDTA was coupled with a thiolated monoclonal antibody (OST7, IgG1) prepared by reducing its disulfide bonds to introduce the ester bond close and proximal to the antibody molecule. For comparison, 1-[4-(5- maleimidopentyl)aminobenzyl]ethylenediamine-N,N,N',N'-tetraacetic acid (EMCS-Bz-EDTA) and meleimidoethyl 3-[131I]iodohippurate (MIH) was coupled to OST7 under the same conjunction chemistry. When incubated in 50% murine plasma or a buffered-solution of neutral pH, OST7-MESS-Bz-EDTA-111In rapidly released the radioactivity, and more than 95% of the initial radioactivity was liberated after a 24 h incubation in both solutions, due to a cleavage of the ester bond. On the other hand, only about 20% of the radioactivity was released from OST7-MIH-131I in both solutions during the same incubation period. In mice biodistribution studies, while a slightly faster radioactivity clearance from the blood with less radioactivity levels in the liver and kidneys was observed with OST7-MIH-131I than with OST7-EMCS-Bz-EDTA-111In, OST7-MESS-Bz-EDTA-111In indicated radioactivity clearance from the blood much faster than and almost comparable to that of OST7-MIH-131I and succinamidobenzyl-EDTA-111In, respectively. These findings as well as previous findings on radiolabeled antibodies with ester bonds suggested that while an introduction of an ester bond close to an antibody molecule stabilized the ester bond against esterase access, chemical structures of the linkages and radiolabels attached to the ester bonds play a significant role in the chemical stability of the ester bond. This may explain the different stability of the ester bonds in radioimmunoconjugates so far reported.

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.

Increased proliferation of eosinophil clusters in myelodysplastic syndromes

A patient with myelodysplastic syndromes (MDS) developed eosinophilia during treatment with recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF). To study the mechanism of this eosinophilia, we investigated the proliferation of eosinophil colony-forming units (CFU-Eo) in nine patients and four healthy controls. Eosinophil clusters increased significantly in the patients (P < 0.01) compared with controls, but eosinophil colonies were not different between controls and MDS patients. In addition, the eosinophil clusters were significantly increased with rhGM-CSF in MDS patients compared with controls, although serum GM-CSF concentrations were similar in both groups. These results suggest that eosinophil clusters are increased in MDS either through abnormal progenitor proliferation or hypersensitivity to GM-CSF.

Normalization of hematocrit with recombinant human erythropoietin in chronic hemodialysis patients does not fully improve their exercise tolerance abilities

In the recombinant human erythropoietin (rHuEPO) treatment of renal anemia, the target level has widely been accepted as approximately 30% of hematocrit (Hct) which means only partial improvement of the anemia. We tried to maintain 1 female and 9 male patients within a normal Hct and to estimate their exercise tolerance abilities. During the study, no serious complications were experienced. Their maximal oxygen uptake (VO2max), evaluated for 1-6 months after reaching the desired Hct of 35-40% with rHuEPO, was 30.7 +/- 2.4 ml of O2/kg/min. These results were significantly higher than those of the control groups whose Hct levels were maintained at around 30%. Although 1 female and 2 male patients were considered to be within the normal exercise tolerance abilities, the others showed lower values in comparison with the Japanese age- and sex-matched values. Thus, it is not always possible to regain full exercise tolerance abilities even after restoring a normal Hct. Unknown factors besides anemia impairing their exercise tolerance abilities might exist in chronic dialysis patients.

Structure and functional analysis of a marine bacterial carotenoid biosynthesis gene cluster and astaxanthin biosynthetic pathway proposed at the gene level

A carotenoid biosynthesis gene cluster for the production of astaxanthin was isolated from the marine bacterium Agrobacterium aurantiacum. This cluster contained five carotenogenic genes with the same orientation, which were designated crtW, crtZ, crtY, crtI, and crtB. The stop codons of individual crt genes except for crtB overlapped the start codons of the following crt genes. Escherichia coli transformants carrying the Erwinia uredovora carotenoid biosynthesis genes provide suitable substrates for carotenoid biosynthesis. The functions of the five crt genes of A. aurantiacum were determined through chromatographic and spectroscopic analyses of the pigments accumulated in some E. coli transformants carrying various combinations of the E. uredovora and A. aurantiacum carotenogenic genes. As a result, the astaxanthin biosynthetic pathway is proposed for the first time at the level of the biosynthesis genes. The crtW and crtZ gene products, which mediated the oxygenation reactions from beta-carotene to astaxanthin, were found to have low substrate specificity. This allowed the production of many presumed intermediates of astaxanthin, i.e., adonixanthin, phoenicoxanthin (adonirubin), canthaxanthin, 3'-hydroxyechinenone, and 3-hydroxyechinenone.

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.

Cyanamide-associated alcoholic liver disease: a sequential histological evaluation

This is the first study that we are aware of that followed the histopathological progression of the liver disease that was caused by the combination of both chronic alcohol use and cyanamide, an antidipsotropic agent. Two sequential liver biopsy specimens were obtained on 29 alcoholics who relapsed with varying histories of cyanamide treatment. Cyanamide induced ground-glass inclusions (GGIs) in the hepatocytes. Two groups were identified, depending on whether GGIs proliferated or regressed, which was, in turn, found contingent on the duration of cyanamide treatment and the drug-free period. Group 1 included 14 cases in which GGIs either emerged only in the second biopsy specimen or else were increased in the second specimen as compared in the initial specimen. Group 2 composed of 15 cases in which GGIs were either not observed in either specimen or decreased in the second specimen as compared in the initial specimen. Acidophilic bodies were sequentially increased in five cases (36%) of group 1 and in none of group 2. The severity of portal inflammation worsened in 10 cases (71%) of group 1 but in 2 cases (13%) of group 2, although the changes in fibrotic process did not differ between two groups. These differences could not be explained on the basis of the daily ethanol consumption and the length of relapses of the two groups. Thus, when cyanamide-treated alcoholics relapsed, the combined effect of cyanamide and alcohol produced the development of acidophilic bodies and portal inflammation along with the emergence of GGIs.

[Mega-dose chemotherapy with peripheral blood stem cell transplantation (PBS-CT) for small cell lung cancer (SCLC)]

Feasibility and the efficacy of mega-dose chemotherapy with peripheral blood stem cell transplantation (PBSCT) for small cell lung cancer (SCLC) were evaluated. Autologous peripheral blood stem cell (APBSC) was collected after induction chemotherapy (Extensive disease: CDDP+etoposide+ADM, Limited disease: CDDP+etoposide) followed by the administration of granulocyte colony stimulating factor (G-CSF). Five cases of ED and 2 cases of LD have been entered in the protocol so far. PBSC was harvested after the second course of induction chemotherapy, and a sufficient number of PBSC (CFU-GM > or = 1 x 10(5)/kg) could be harvested and cryopreserved in all 7 cases. After completion of 4 courses of induction chemotherapy, three patients who achieved CR or good PR were treated by the combination of CBDCA (1,600 mg/m2) plus etoposide (1,600 mg/m2) followed by APBSCT and G-CSF. Hematologic recovery after APBSCT was rapid (absolute granulocyte count > 500/microliters: 9-11 day, Plt > 3 x 10(4)/microliters:10-14 day) and no infectious episode nor bleeding tendency occurred throughout the treatment period. Although grade 3 gastrointestinal toxicity was seen in one patient, the mega-dose chemotherapy with APBSCT in SCLC was considered safe and feasible. Further clinical trials are needed to establish the role of mega-dose chemotherapy for the treatment of SCLC.

Dermatofibroma with myxoid changes in a patient with psoriasis

A 38-year-old female with psoriatic arthritis developed a dermatofibroma (DF) on her upper arm. Its position was not exactly on a psoriatic plaque; however, psoriatic lesions were present diffusely around the DF lesion. Histological examination revealed the typical features of DF with myxoid changes in the portion between the tumor nest and the overlying epidermis. The mast cell number was significantly increased over that of solitary DFs without myxomatous lesions. It was suggested that mast cells may play a role in induction of the myxoid changes in the DF lesion in this case.

[Development of infection with Aspergillus flavus in woman being treated for allergic pulmonary Aspergillosis caused by Aspergillus fumigatus]

A 36-year-old woman who raised plants in a large greenhouse came to our hospital because of a cough and purulent sputum. A chest X-ray film showed infiltrative shadows in the left middle lung field. Aspergillus fumigatus was isolated from samples of sputum and bronchoalveolar lavage fluid obtained from the left B5. Biopsy specimens revealed hyphae elements of aspergillus species and eosinophils in a plug of viscous material. Also, eosinophils and lymphocytes had infiltrated through bronchial epithelium without aspergillus species. She was given a diagnosis of allergic aspergillosis caused by Aspergillus fumigatus. Fluconazole was given and her symptoms and infiltrative shadows improved. Seventy days after treatment with fluconazole began, her symptoms recurred along with an abnormal shadow in the left upper lung field on a chest x-ray film. Aspergillus flavus, but not Aspergillus fumigatus, was isolated from samples of sputum and bronchoalveolar lavage fluid obtained from the left lung (S1+2). Biopsy specimens of the lung showed eosinophilic pneumonia. She was treated with itraconazole and her symptoms and abnormal radiographic shadows disappeared. She had no asthmatic attack or central bronchiectasis du ring the illness. This was a case of allergic pulmonary aspergillosis without asthmatic symptoms. It is interesting that one species of aspergillus was replaced by another during treatment.

Species differences in anticoagulant and anti-Xa activity of DX-9065a, a highly selective factor Xa inhibitor

Activation of the blood coagulation cascade results in the formation of factor Xa (FXa) in either its intrinsic or extrinsic pathways, which in turn converts prothrombin to thrombin. We recently described the synthesis and characterization of DX-9065a, a highly selective FXa inhibitor, as an orally active anticoagulant agent (1). Although DX-9065a potently inhibited human FXa (2), a much larger dosage was required to inhibit thrombus formation in a rat thrombosis model (3): The plasma concentration of DX-9065a after administration of a dose which reduced thrombus formation by 50% in rats was in the microM range, or 40 times higher than the Ki value for FXa. From this, several assumptions arise, namely that an unknown mechanism other than FXa inhibition contributes to the antithrombotic effect of DX-9065a, or that the efficacy of DX-9065a differs among species. However, as the anticoagulant effect of DX-9065a was closely consistent with anti-Xa activity in plasma and as DX-9065a inhibited only FXa activity (2), the former assumption could be disregarded. To clarify the latter, we examined the inhibitory effect of DX-9065a on FXa from several animal species and its anticoagulant effect ex vivo in these species. Further, we also compared the anticoagulant effect of DX-9065a in plasma from each species with that of NAPAP, a benzamidine-derived direct thrombin inhibitor (4).

Isolation, characterization and chromosomal mapping of an actin gene from the primitive red alga Cyanidioschyzon merolae

Based on the results of cytological studies, it has been assumed that Cyanidioschyzon merolae does not contain actin genes. However, Southern hybridization of C. merolae cell-nuclear DNA with a yeast actin-gene probe has been suggested the presence of an actin gene in the C. merolae genome. In the present study, an actin gene was isolated from a C. merolae genomic library using a yeast actin-gene probe. The C. merolae actin gene has no intron. The predicted actin is composed of 377 amino acids and has an estimated molecular mass of 42 003 Da. Southern hybridization indicated that the C. merolae genome contains only one actin gene. This gene is transcribed at a size of 2.4 kb. When Southern hybridization was performed with C. merolae chromosomes separated by pulsed-field gel electrophoresis, a band appeared on unseparated chromosomes XI and XII. A phylogenetic tree based on known eucaryote actin-gene sequences revealed that C. merolae diverged after the division of Protozoa, but before the division of Fungi, Animalia and Chlorophyta.

Successful screening for early esophageal cancer in alcoholics using endoscopy and mucosa iodine staining

BACKGROUND

Epidemiologic studies have provided evidence that alcohol abuse is an important risk factor for esophageal carcinoma. However, no systematic screening program has been established yet in the early detection of esophageal cancer in high risk populations of heavy drinkers.

METHODS

A cohort of 629 male alcoholics (54 +/- 8 years old) were consecutively and systematically screened by endoscopy combined with iodine staining and targeted biopsy at the National Institute on Alcoholism (Kanagawa, Japan). For mucosal carcinomas, endoscopic esophageal mucosal resection (EEMR) was used to serve confirmatory diagnostic and therapeutic purposes.

RESULTS

Iodine-unstained lesions, distinctly demarcated, white, and 5 mm or larger in greatest dimension, were observed on the esophageal wall in 162 patients (25.8%). Thirty-six such unstained lesions in 21 of 629 patients, with an unexpectedly high rate of 3.3%, turned out to be squamous cell carcinomas of the superficial type. According to some established criteria, EEMR was performed in 17 of these patients, 3 of whom were given additional irradiation. Esophagectomy was performed in two patients, chemotherapy combined with irradiation in one, whereas still another was followed endoscopically. The cancer invasion was confined within the epithelium in eight patients, to the proper mucosal layer in nine, and to the submucosa in four. Multiple logistic regression revealed that the risks for distinct iodine-unstained lesions and superficial esophageal carcinoma increased independently for users of stronger alcoholic beverages, i.e., whiskey or shochu (odds ratio [OR] = 1.47 and 2.94, respectively) compared with lighter beverages, i.e., sake or beer and 30+ cigarettes/day (OR = 1.68 and 3.85, respectively).

CONCLUSION

Routine application of this program for these high risk individuals yielded an unusually high rate of detection of esophageal carcinoma.

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.

Cu-pyruvaldehyde-bis(N4-methylthiosemicarbazone) (Cu-PTSM), a metal complex with selective NADH-dependent reduction by complex I in brain mitochondria: a potential radiopharmaceutical for mitochondria-functional imaging with positron emission tomography (PET)

The reductive retention mechanism of copper(II)-pyruvaldehyde-bis (N4-methylthiosemicarbazone) (Cu-PTSM), a generator-produced positron-emitting 62Cu-labeled radiopharmaceutical, was studied with non-radioactive and radioactive copper. Changes in the chemical form of Cu-PTSM were detected by electron spin resonance spectrometry (ESR) with cold copper. The effects of electron transport chain inhibitors on the reduction of Cu-PTSM were also examined. Rotenone and antimycin A activated the reduction of Cu-PTSM in the brain mitochondria by 1.6- and 1.4-fold, respectively, compared with untreated controls, while thenoyltrifluoroacetone (TTFA) had no effect on the reduction. These results were confirmed with radioactive copper. Furthermore, this reduction of Cu-PTSM was dependent on the protein concentration of mouse brain submitochondrial particle (SMP) with 1 mM NADH (0 mg-protein/ml: 1.8 +/- 2.5%, 8 mg-protein/ml: 69.0 +/- 5.5%, each value was % of reduced Cu). Similarly, this reduction depended on NADH concentration at a fixed concentration of SMP (8 mg-protein/ml). These results indicated that the electron transport chain, especially complex I, participated in the reduction of Cu-PTSM in brain mitochondria, and this suggested that Cu-PTSM has the potential to act as a functional imaging agent for diagnosis of the electron transport chain.

DX-9065a, an orally active, specific inhibitor of factor Xa, inhibits thrombosis without affecting bleeding time in rats

We evaluated the antithrombotic effects of DX-9065a, a specific factor Xa inhibitor, using tissue thromboplastin-induced DIC (TP-DIC) and the arterio-venous shunt (AV shunt) in rats. Intravenous TP injection reduced the platelet counts and fibrinogen concentrations in blood. In the TP-DIC model, an intravenous dose of DX-9065a 0.23 mg/kg 1 min before TP injection suppressed the consumption of platelets and fibrinogen to 57% and 66%, respectively, and the production of FDP almost completely. In the AV shunt model, DX-9065a inhibited thrombus formation to 51% on intravenous administration of 0.23 mg/kg and to 60% when given orally at 23.3 mg/kg. Intravenous administration of 2.33 mg/kg of DX-9065a did not affect the bleeding time. These results suggest that Xa inhibition may be an appropriate approach for suppressing thrombosis without impairing haemostasis.

IgG and IgM rheumatoid factor levels parallel interleukin-6 during the vasculitic phase in a patient with Churg-Strauss syndrome

A 43-year-old woman with a 10-year history of bronchial asthma developed marked peripheral blood eosinophilia and symptoms of vasculitis. A diagnosis of Churg-Strauss syndrome (CSS) was made, and her symptoms were successfully treated with low-dose prednisolone. Serum rheumatoid factors (RF) of both IgG and IgM, but not IgA or IgE, subclasses transiently appeared in accordance with the vasculitic phase. Serum interleukin-6 (IL-6) levels also transiently increased in this phase and the peak level was reached just prior to the maximum of RF elevation, suggesting the role of IL-6 as an inducer of RF. RF and IL-6 seemed to be involved in the pathogenesis of the vasculitis in this patient.

Digestibility characteristics of isomaltooligosaccharides in comparison with several saccharides using the rat jejunum loop method

Isomaltooligosaccharides (IMO) are a mixture of isomaltose, isomaltotriose, panose, isomaltotetraose, etc. IMO and its hydrogenated derivative (IMH) were characterized for their luminal clearance from rat jujunum loops as the indication of their digestibility. They were compared with a disaccharide fraction (IM2) and a higher oligosaccharide fraction (IM3) prepared from IMO, typical digestible saccharides (maltose, maltotriose, and sucrose), and typical nondigestible saccharides (maltitol, raffinose, and fructooligosaccharides (FO)). The clearance rate of IMO was significantly smaller than that of IM2, which was mainly composed of isomaltose (64.3%), and digestible saccharides, and significantly larger than that of nondigestible saccharides. That of IM2 was almost the same as that of sucrose or maltotriose but significantly smaller than that of maltose. That of IM3 tended to be smaller than that of IMO, and larger than that of nondigestible saccharides. That of IMH was significantly smaller than that of IMO and similar to that of maltitol. These results seem to indicate that IMO is slowly digested in the jejunum, that the components having higher degree of polymerization of IMO are less digestible, and that IMH is nondigestible.

[A case of chylothorax caused by mesenteric panniculitis]

A 76-year-old female was referred to our hospital for examination of milky pleural effusion. We diagnosed her illness as chylothorax because of the high concentration of triglyceride in the effusion. There was neither obstruction nor damage of the thoracic duct. Systemic evaluation disclosed an abdominal mass in the umbilical region. Fasting with intravenous hyperalimentation followed by pleurodesis with minocycline successfully eliminated the effusion. On the other hand, the abdominal mass was diagnosed as mesenteric panniculitis by open biopsy. Since she also had chylous ascites, the tumor could have obstructed the intestinal lymphatics. Chylothorax was probably caused by damage to collateral lymph circulation.