4-Borono-2-[18F]fluoro-D,L-phenylalanine: a possible tracer for melanoma diagnosis with PET

The potential of 4-borono-2-[18F]fluoro-D,L-phenylalanine ([18F]FBPA), a flurodinated derivative of a target compound for boron neutron capture therapy, for melanoma imaging by positron emission tomography (PET) was studied using animal models. A high uptake of [18F]FBPA was found in murine B16 melanoma or in Greene's melanoma No. 179, a melanotic cell line in hamsters, for the first 6 h after injection. Whole body autoradiography using [18F]FBPA gave a clear image of the B16 tumor. The acid-insoluble 18F in the B16 increased to 27% by 6 h, and most of the free 18F was detected as [18F]FBPA in both B16 and plasma. In the hamster models, No. 179 showed a 1.7 times higher uptake than amelanotic Greene's melanoma No. 178 at 6 h post-injection, although both melanomas indicated similar metabolic activities when examined by a tracer uptake study using L-[14C]methionine, 2-deoxy-D-[14C]glucose and [3H]thymidine. [18F]FBPA may be a very promising PET tracer for melanoma imaging.

Role of excision repair in UVB-induced depletion and recovery of human epidermal Langerhans cells

Skin exposure to UVB radiation deprives the antigen-presenting function and OKT6 monoclonal antibody-binding characteristics of Langerhans cells. Decrease of Langerhans cell population could be relevant to immune surveillance disturbance in the UV-exposed skin. Patients with xeroderma pigmentosum exhibit a thousandfold higher risk for sunlight-induced skin cancers than patients with normal skin, and also have various defects in cellular immunity. Therefore, studies of numerical and structural changes in epidermal Langerhans cells of patients with xeroderma pigmentosum after UVB irradiation compared with normal subjects may contribute to understanding the role of antigen-presenting cells in photocarcinogenesis. The effect of UVB radiation on OKT6+ Langerhans cells was studied in epidermal sheets obtained from irradiated normal subjects (36 and 49 years old) and subjects with xeroderma pigmentosum complementation group A (21 years old), complementation group D (32 years old), and variant (35 and 60 years old). Langerhans cell densities in chronically sunlight-exposed skin were remarkably reduced in patients with xeroderma pigmentosum group A but only slightly in those with xeroderma pigmentosum variant and in normal subjects compared with covered skin. Structural changes were substantial in Langerhans cells of chronically exposed patients with xeroderma pigmentosum group A but fewer in subjects with other xeroderma pigmentosum groups and in normal subjects. A single irradiation of three times the minimal erythema dose induced a large reduction of Langerhans cells from 3 to 7 days in all subjects. However, subsequent reappearance and return to preirradiated levels was delayed more in patients with xeroderma pigmentosum group A than in those with xeroderma pigmentosum variant and normal subjects. These results indicate (1) an essential role for excisional repair in the UVB-induced depletion, recovery, and maintenance of the epidermal Langerhans cell population, and (2) a possible, but not confirmed, relationship between depletion of Langerhans cells and earlier photocarcinogenesis in xeroderma pigmentosum.

Thermal neutron capture therapy of malignant melanoma using 10B-monoclonal antibodies: in vitro and in vivo analysis

We have established methods of targeting a sufficient number of 10B atoms on human melanoma cells to allow selective destruction of the cancer cells by thermal neutron irradiation. Thermal neutron capture therapy (NCT)1-3 requires the presence of at least 10(9) 10B atoms on each target cell for specific killing of that cell without injuring normal tissues. In order to accumulate an adequate number of 10B atoms on target cells, we first created an effective compound containing 12 atoms of 10B per molecule (10B12-chlorpromazine) and 10B-dopa analogue (10B1-paraboronophenylalanine). In the present study, about three molecules of our newly synthesized 10B12-compound were conjugated to an avidin molecule. The resulting 10B38.5-avidin compound can be specifically directed to human melanoma cells by biotinated monoclonal antibodies (MAbs) specific for the cells. We were able to accumulate 2.6 x 10(8) 10B atoms on a melanoma cell using this method. Cultured human melanoma cells treated with 10B-avidin-biotin-MAb (10B-AB-MAb) were selectively damaged by thermal neutron irradiation in vitro. This is the first study to indicate that thermal neutrons selectively damage target cells boronated by MAbs.

Studies on nilvadipine. I. Synthesis and structure-activity relationships of 1,4-dihydropyridines containing novel substituents at the 2-position

The synthesis of new 1,4-dihydropyridine derivatives containing novel substituent at the 2-position of the nucleus via the key intermediate 2-formyl-1,4-dihydropyridines (X), is described. The aldehydes (X) were prepared by hydrolysis of the acetals (IX) which were obtained from aryl aldehyde (V) and alkyl 4,4-dialkoxyacetoacetate (VI) by the Knoevenagel reaction and treatment with alkyl 3-aminocrotonate (VIII) according to the modified Hantzsch method. The formyl group of the aldehydes (X) was reactive enough to be converted to a variety of functional groups such as hydroxymethyl, cyano, substituted iminomethyl, carbamoyl, semicarbazone, substituted vinyl, ethynyl, and so on. In all of the novel compounds we prepared, 2-hydroxymethyl- and 2-cyano-1,4-dihydropyridines (IV and XXII) were found to possess potent activities in preliminary biological evaluations on hypotension in normotensive rats and on an increase in coronary blood flow in pentobarbital-anesthetized dogs. Optimization research in order to obtain a more potent compound was accomplished in the 2-hydroxymethyl- and 2-cyano-1,4-dihydropyridine series. We selected isopropyl 2-cyano-3-methoxycarbonyl-4-(3-nitrophenyl)-6-methyl-1,4-dihydropyridine -5-carboxylate (XXIIj) as a candidate compound for further biological evaluation studies. Fortunately, XXIIj (nilvadipine) has been accepted in clinical use for the treatment of hypertension.

Increase of sialylated tetraantennary sugar chains in parallel to the higher lung-colonizing abilities of mouse melanoma clones

The N-linked sugar chains of melanoma cell membrane from five murine B16 melanoma clones (F1, F10, BL6, W1-4, and C4-1) with different degrees of metastatic abilities after intravenous and intrafootpad injections were released quantitatively as oligosaccharides by hydrazinolysis, and their structures were analyzed by serial lectin column chromatography, Bio-Gel P-4 column chromatography, and sequential glycosidase digestion. Sugar chain structures of each clone have shown to consist of the same elemental oligosaccharides, but to differ in their percent compositions. More than 84% of the neutral oligosaccharides were high mannose-type sugar chains. Most complex-type sugar chains were sialylated, of which the major structure was tetraantennary sugar chain. Highly lung-colonizing F10 cells had 1.4 and 1.7 times more non-repeated tetraantennary sugar chains than moderately colonizing F1 and C4-1 cells, respectively, and 2.5 times more than poorly colonizing W1-4 cells. BL6 cells, which are also highly lung-colonizing, had 1.5 and 1.9 times more non-repeated tetraantennary sugar chains than F1 and C4-1 cells, respectively, and 2.8 times more than W1-4 cells. These results suggest that increase of sialylated tetraantennary complex-type sugar chains without N-acetyllactosamine repeating units of B16 melanoma cells might correlate with the higher lung-colonizing ability after intravenous injection.

Effect of dopa-loading on glutathione metabolising enzymes and tyrosinase in relation to 5-S-cysteinyl-dopa genesis in cultured B-16 melanoma cells

The effect of DOPA and glutathione (GSH) on enzyme systems for 5-S-cysteinyl-DOPA (5SCD) genesis in murine melanoma cells cultured in tyrosine- and cystine-free medium were studied. DOPA at its optimum concentration (10(-5) M) when added alone did not alter tyrosinase, glutathione-S-transferase or gamma-glutamyl transpeptidase activities. In the presence of GSH at its optimum concentration (10(-5) M), DOPA loading did not cause any significant changes in tyrosinase or glutathione-S-transferase (GST) activities. This indicates that the higher 5SCD levels observed in the medium because of DOPA loading in the GSH dependent system results from increased substrate availability rather than the increased enzyme activity. An acute drop in 5SCD at DOPA concentrations above 10(-5) M observed in the GSH dependent system may be due to the inhibition of tyrosinase at high substrate concentrations (10(-4) M). Conversely, in the presence of DOPA, when GSH was increased, the resultant higher production of 5SCD could be explained by the increased activity of GST. When added alone, GSH (10(-5) M) caused a significant increase in GST (approximately 125%) and gamma-GTP (approximately 50%) activities. A drop in 5SCD in the medium when GSH was added beyond its optimum concentration (10(-5) M) in the DOPA-dependent system could be due to competitive inhibition of gamma-GTP by GSH. The data demonstrate that 5SCD genesis may be enhanced due to the accumulation of cytotoxic melanin precursors such as DOPA/DOPA quinone. The relative quantities of GSH at the sites of DOPA quinone formation and the levels of its metabolising enzymes can influence the type of product formed.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of corrosive esophagitis with stenosis]

A 41-year-old man was admitted to our hospital because of pharyngeal pain and vomiting after intentionally swallowing sodium hydroxide. Gradually esophageal stenosis took place. After 9 months from the taking poison the patient was operated. We tried blunt dissection of esophagus. But the procedure failed in because the wire of stripper was cut. So performed total esophageal resection under the right thoracotomy. The right side colon was used to re-construction through antero-sternal space that was anastmosed to cervical esophagus and stomach. The postoperative course was uneventful.

Malignant schwannoma associated with xeroderma pigmentosum in a patient belonging to complementation group D

A 43-year-old man with xeroderma pigmentosum, XP97TO, was allocated to complementation group D. He had had moderate photosensitivity at age 1 year and freckles by age 6 but no neurologic abnormalities. Nevertheless, his fibroblasts in culture had the XP-D phenotype. They showed a sevenfold hypersensitivity to killing by 254 nm ultraviolet radiation and a diminished level (29%) of unscheduled DNA synthesis. Phototesting revealed delayed maximum erythema at 72 hours after UVB exposure and a lowered minimal erythema dose. Lentigo maligna developed on the patient's face, and a rapidly growing malignant schwannoma was found on the left trigeminal nerve. This may be the first case of a peripheral nervous tissue neoplasm in xeroderma pigmentosum.

4-Borono-2-[18F]fluoro-D,L-phenylalanine as a target compound for boron neutron capture therapy: tumor imaging potential with positron emission tomography

We studied the tumor uptake and metabolism of 4-borono-2-[18F]fluoro-D,L-phenylalanine ([18F]FBPA), an 18F-labeled target compound for boron neutron capture therapy. In mice bearing FM3A mammary carcinoma, the accumulation of [18F]FBPA in the FM3A for the first 2 h, and its decrease in all other tissues, resulted in high FM3A-to-tissue uptake ratios. In the FM3A, the tracer was stable for metabolic alteration, which was in contrast to the gradual increase of protein-bound radioactivity in plasma. Imaging of FM3A was demonstrated by whole body autoradiography. [18F]FBPA has potential for use as a PET tracer for tumor imaging with high contrast, even in the pancreas.

Synthesis and radiation dosimetry of 4-borono-2-[18F]fluoro-D,L-phenylalanine: a target compound for PET and boron neutron capture therapy

The 18F-labeling of 4-borono-D-L-phenylalanine (BPA), a potential target compound for cancer treatment with boron neutron capture therapy, is described. By direct fluorination of BPA with [18F]AcOF or [18F]F2 followed by HPLC separation, 4-borono-2-[18F]fluoro-D,L-phenylalanine was prepared with radiochemical yields of 25-35% and with a radiochemical purity of over 99%. The tissue distribution study showed that the compound has potential as a tracer for pancreas imaging with positron emission tomography. Radiation dosimetry is also described.

Protein kinase C and linoleic acid-induced inhibition of melanogenesis

Linoleic acid has been shown to inhibit melanogenesis in cultured B16 mouse melanoma cells. We report here the possible involvement of protein kinase C (PKC) in linoleic acid-induced inhibition of melanogenesis in B16 cells. A single PKC subspecies (alpha-PKC) was detected in B16 cells. The enzyme was activated by linoleic acid in vitro. The effective concentrations at which PKC was activated (25 microM; maximum response) were consistent with those for the inhibition of melanogenesis in cell culture system. In addition, the permeable diacylglycerol 1-oleoyl-2-acetyl glycerol that activates PKC also inhibits melanogenesis at 100 microM. These results suggest that activation of PKC plays a pivotal role in the linoleic acid-induced inhibition of melanogenesis in B16 cells.

An acoustically investigated case of phonetic change in higher vertical dimension

This report presents the phonetic changes of a patient whose occlusal vertical dimension is extended. His chief complaint is esthetic restoration of his anterior teeth, but his occlusal vertical dimension is abnormally shortened by long-time attrition. Therefore we extended his occlusal vertical dimension, and reconstructed his occlusion, and carried out acoustic observations.

In situ detection of cutaneous melanoma by prompt gamma-ray spectrometry using melanoma-seeking 10B-dopa analogue

10B1-para-boronophenylalanine (10B1-BPA), one of our boronated dopa analogues developed for thermal neutron capture therapy, has been found to have a selective affinity for malignant melanoma. We have established a method of 'in situ' detection of subcutaneous melanoma lesions, using this melanoma-seeking 10B-labeled compound. In this study, we applied an 'in situ' 10B microanalysis system via detection of the prompt gamma-ray from the 10B(n, alpha)7Li reaction triggered by irradiating the 10B-containing target with pure thermal neutrons, called prompt gamma-ray spectrometry, to hamsters bearing Greene's melanoma in subcutis and to a human patient whose occipital subcutaneous tumor was suspected of being a metastatic melanoma. In the hamsters, the time-dependent 10B dynamics showed increased 10B accumulation in melanoma, after 10B1-BPA administration, in contrast to that in non-melanoma normal skin. In the human patient, after subcutaneous injection of 10B1-BPA into perilesional sites 4 cm distant from the tumor margin, the average 10B concentration in the tumor was determined to be 24 ppm (microgram/g), in contrast to 3 ppm in skin covering the tumor and 1.1 ppm in blood, indicative of selectively high 10B1-BPA uptake by the tumor.

Melanogenic regulatory factors in coated vesicles from melanoma cells

Coated vesicles have been found to contain much higher tyrosinase and gamma-glutamyl transpeptidase activities than premelanosomes. This indicates that similar to tyrosinase, gamma-glutamyl transpeptidase, an enzyme responsible for pheomelanogenesis, is highly concentrated in coated vesicles after its maturation in Golgi associated endoplasmic reticulum (GERL). Furthermore, in the pre- and post-dopaquinone melanogenic pathway, coated vesicles convert dopachrome to colorless indole compounds more quickly than in premelanosomes because of their higher dopachrome conversion factor activity. Melanosomes have been found to exhibit indole conversion factor activity, while coated vesicles show indole blocking factor activity. In moderately tyrosinase-rich premelanosomes, the levels of dopachrome conversion factor and indole blocking factor are lower than in coated vesicles or melanosomes. High levels of indole blocking factor in coated vesicles may indicate why melanin polymer formation does not occur there in vivo despite their high tyrosinase activity.

Repair of 254 nm ultraviolet-induced (6-4) photoproducts: monoclonal antibody recognition and differential defects in xeroderma pigmentosum complementation groups A, D, and variant

Repair kinetics of ultraviolet (UV) light-induced (6-4) photoproducts in xeroderma pigmentosum complementation group A, D, and variant cells were studied by the enzyme-linked immunosorbent assay (ELISA) using a specific monoclonal antibody raised against (6-4) photoproducts, together with unscheduled DNA synthesis (UDS) and loss of T4 endonuclease V-susceptible sites (ESS). Group AXP35KO cells completely failed to repair both ESS (cyclobutane pyrimidine dimers) and antibody-recognizing (6-4) photoproducts until tested 24 h after irradiation, and had 2% early-time UDS. Group DXP43KO cells showed about 10% removal of both (6-4) photoproducts and ESS in 24 h, despite showing a residually higher level of 40% early-time and cumulative UDS. Thus, the results substantiated the extreme UV hypersensitivity of XP group A and D cells. However, XP52KO variant cells exhibited the normal level of UDS and ESS loss, but a slightly reduced repair of antibody-recognizing (6-4) photoproducts at 6 and 12 h after irradiation, which may account for a small UV hypersensitivity of the XP variant cells.

Biochemical analysis of metastasis-related Ax actin in B16 mouse melanoma cells after chemical reversional modulation and of tumor progression-related A' actin in the ontogeny of human malignant melanoma

To examine the correlation between tumor metastasis and Ax actin in mouse melanoma and between tumor progression and A'.actin in human melanoma and further to investigate whether or not it is a generally existing principle, we studied the effects of reversion agents, which distinctly decrease metastatic ability of melanoma cells, on the appearance of Ax actin. Will an induced decrease in metastasis of established highly metastatic B16-F10 mouse melanoma cells cause the appearance of Ax actin? We also examined the appearance of A' actin in eight human benign pigment cell tumors and nine human malignant melanoma tissues or cells in relation to tumor progression. In vitro treatment of B16-F10 cells with each of these agents suppressed metastatic ability of the cells injected intravenously into syngenic mice; however, none of the treated cells represented Ax actin in vitro. These results suggest that the appearance of Ax actin may be a result of long-term tumor cell progression leading to changes in gene level, but because the treatments with these agents were only carried out over a short period, they could not effect changes in gene level; thus, Ax actin appearance remained unchanged. Appearance of A' actin was detected only in human benign pigment cell tumors such as nevus cell nevi, but not in malignant melanomas, which were also formed in a long period of tumor progression in vivo. These results suggest that A' actin is a clinically useful marker to determine the prognosis and level of tumor progression of human pigment cell tumors.