Colorimetric chemosensitivity testing using sulforhodamine B

A colorimetric chemosensitivity test was investigated using sulforhodamine B (SRB), which stains protein synthesized by cells, as an end-point marker. Four cultured cell lines, 9 human tumor xenografts serially transplanted into nude mice, and 14 fresh surgical specimens were subjected to this assay. The optimal conditions for the assay were 3-5 x 10(4) cells per well in a 96-microplate, an SRB concentration of 4%, and an incubation time of more than 10 minutes. When mitomycin C, doxorubicin, cisplatin, and 5-fluorouracil were assessed by the SRB assay, the concentration-effect curves revealed a sharp slope between plateaux at low and high concentrations, suggesting that this assay has an excellent sensitivity which can assess the effect of drugs as "all or none." Although this high sensitivity resulted in good reproducibility of the assay for cultured cell lines, the predictive rate of the SRB assay for the chemosensitivity of human tumor xenografts in vivo was limited to 63.9%. As a result, this SRB assay is thought to be useful for evaluating the chemosensitivity of cultured cells as all or none, since it can assess directly cellular protein synthesis, which is one of the most important parameters of cell renewal, with excellent sensitivity.

Hyperthermia induced by the dopamine D1 receptor agonist SK&F38393 in combination with the dopamine D2 receptor agonist talipexole in the rat

The present experiments were performed to investigate the effects of dopamine D1 receptor agonists given alone or in combination with dopamine D2 receptor agonists on body temperature in rats. The selective dopamine D1 receptor agonist, 1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol (SK&F38393), produced hyperthermia. However, the dopamine D2 receptor agonist, B-HT 920 (talipexole), and the newly synthesized dopamine D2 receptor agonist, (S)-2-amino-4,5,6,7-tetrahydro-6-propylamino-benzothiazole (SND 919), did not change the temperature. Interestingly, the SK&F38393-induced hyperthermia was enhanced by talipexole and SND 919. The drastic hyperthermia induced by combined administration of dopamine D1 and D2 receptor agonists was blocked by either the dopamine D1 receptor antagonist, SCH23390, or the dopamine D2 receptor antagonist, spiperone. On the other hand, treatment with prazosin, yohimbine, propranolol, scopolamine, or methysergide failed to affect the marked hyperthermia. The present results suggest that a functional link between dopamine D1 and D2 receptors may be synergistic in the regulation of body temperature and that concurrent stimulation of both dopamine D1 and D2 receptors thereby produces marked hyperthermia in the rat.

Experimental cancer chemotherapy using a liver metastatic model of human colon cancer transplanted into the spleen of severe combined immunodeficient mice

We have developed a liver metastatic model of human colon cancer using severe combined immunodeficient (SCID) mice. Liver metastases were observed in all the SCID mice on day 28 after intrasplenic injection with 5 x 10(6) dissociated tumor cells of COL-2-JCK, a human colon cancer strain serially transplanted in nude mice. When this model was applied for chemotherapeutic experiments, 5-fluorouracil (5-FU) demonstrated significant antitumor effects in preventing liver metastases, whereas the efficacy of 5-FU was limited in the currently used sc-ip chemosensitivity assay in nude mice. When the human LDH-5 isozyme was evaluated in the homogenized metastatic liver tissue of SCID mice, a good correlation was obtained between the liver tumor weights and LDH-5 isozyme, suggesting that it could be a promising quantitative indicator for metastases. This model would be useful for further studies on the treatment of liver metastases of colon cancer.

Low-threshold motor effects produced by stimulation of the facial area of the fifth somatosensory cortex in the cat

The motor effective sites of the fifth somatosensory cortex (SV) in the cat were mapped in detail by using unit recording and intracortical microstimulation (ICMS) techniques. The motor effective sites for facial muscle contraction were identified using stimulus currents of less than 30 microA. Of the 257 effective sites detected, 49% were activated by stimulus currents of less than 20 microA and of these, 51% responded to stimulus currents of less than 10 microA. ICMS within the facial area of the SV neuron produced contralateral eye-blinking, the lowest threshold current for which was 2 microA and ICMS within the SV neurons produced whisker movements, the minimum threshold current for which was 4 microA. Furthermore, stimulation of some SV neurons at a threshold current as low as 4 microA produced whisker movements and some responded to both visual and cutaneous stimuli. Ablation of areas 6a beta, 3a, SII, SIII and the motor cortex did not eliminate or reduce the low-threshold responses elicited by this weak stimulation of the SV. These motor effective areas receive input from the contralateral cutaneous of the surrounding muscle motor effective region. Our results suggest that the described effect is independent of motor effective areas.

Possible transsynaptic cholinergic neuromodulation by ATP released from ileal longitudinal muscles of guinea pigs

The effects of alpha, beta-methylene ATP (alpha, beta-mATP) and beta, gamma-methylene ATP (beta, gamma-mATP) on endogenous acetylcholine (ACh) release evoked by electrical nerve stimulation were evaluated in guinea-pig ileal longitudinal muscles. Release of ACh was measured with an HPLC-electrochemical detector system and release of ATP by luciferin-luciferase assay. Electrically evoked endogenous ACh release was reduced by both alpha, beta-mATP and beta, gamma-mATP at concentrations of 3 and 30 microM. The inhibitory effect of alpha, beta-mATP (30 microM) on ACh release was not detectable in the presence of theophylline (100 microM), a P1-purinoceptor antagonist, that itself enhanced ATP release. When exogenous ATP (0.1 microM) was added to the bath in which the ileal segment was suspended, it was rapidly metabolized, presumably by ecto-ATPase, and disappeared from the medium within 15 min. At 30 microM, alpha, beta-mATP induced ATP release in a suramin-sensitive but Ca(2+)- and atropine-insensitive manner, suggesting P2-receptor-mediated release of ATP from the smooth muscle. We conclude from these findings that alpha, beta-mATP and, probably, also beta, gamma-mATP, do not reduce ACh release by direct stimulation of presynaptic P1-purinoceptors, and that endogenous ATP released postjunctionally by these ATP analogs is decomposed metabolically to adenosine in the synapse and this adenosine triggers P1-purinoceptor sensitive neuromodulation of cholinergic transmission.

MRI of intradural-extramedullary spinal neurinomas and meningiomas

The magnetic resonance images of 16 patients with intradural-extramedullary spinal tumors, consisting of 11 neurinomas and five meningiomas were reviewed. The neurinomas appeared hypointense compared to the spinal cord on unenhanced T1-weighted images (T1WI) in nine of 11 patients, and hyperintense on T2-weighted images (T2WI) in nine of 11 patients. Neural foraminal extension was present in two cases. All 10 neurinomas were markedly enhanced; six of them exhibited ring-like enhancement on Gadolinium-DTPA (Gd-DTPA)-enhanced T1WI. The meningiomas appeared isointense on unenhanced T1WI in four of five patients and on T2WI in three of four patients. Three meningiomas showed moderate homogeneous contrast enhancement after the intravenous administration of Gd-DTPA. It is concluded that careful scrutiny of magnetic resonance images facilitates the differential diagnosis of spinal neurinomas and meningiomas.

Antibodies to human cytomegalovirus 65-kilodalton Fc binding protein in rheumatoid arthritis: idiotypic mimicry hypothesis of rheumatoid factor production

We previously reported that rheumatoid factors (RFs) might bear the internal image of Fc gamma-binding proteins (FcBPs) of herpes family viruses, suggesting the possibility that some RFs may be produced as antiidiotypic antibodies to anti-viral FcBP antibodies. Since human cytomegalovirus (HCMV) has been implicated in the pathogenesis of RA, we made an attempt to detect antibodies to 65 KD major HCMV FcBP in sera and synovial fluid from patients with RA. Western blotting was performed using HCMV-infected MRC-5 cell lysate as the antigen. Eleven of 23 patients with RA possessed strong serum antibodies to HCMV-65 KD protein, whereas such antibodies were found in only 2 of 23 normal controls. In the synovial fluid, 10 of 19 RA patients showed anti-HCMV 65 KD reactivity. Pepsin-digested IgG retained anti-65 KD reactivity, indicating that false-positive reaction due to the presence of IgG Fc portion and/or RF was unlikely. 65 KD protein was shown to be different from human heat shock proteins (hsps) using monoclonal antibodies against human hsps. Patients' IgG F(ab')2 also reacted with the 65 KD protein of purified HCMV virion itself. These results support the possibility that some RFs could be produced as antiidiotypic antibodies to anti-viral FcBP antibodies.

Antitumor activity and interleukin-1 induction by tannins

The relationships between structures, antitumor activities and interleukin-1 (IL-1) induction by fifteen tannins were studies. When tannins (10 mg/kg) were intraperitoneally injected into mice once, 4 days before intraperitoneal inoculation of S-180 cells, tellimagrandin II, rugosin A, hirtellin B, oenothein B and oenothein A, which have only tellimagrandins I or II units in their molecules, had significant antitumor activity. Although casuarictin and its related tannins were ineffective, agrimonin, which is a dimer, had a strong effect, as previously reported. On the other hand, monomeric ellagitannins such as tellimagrandins I and II, rugosin A and casuarictin also increased IL-1 beta production from human peripheral macrophages in vitro by 2-fold over the non-stimulated basal production and oligomeric ellagitannins with strong antitumor activity more potently stimulated the IL-1 beta induction. Other tannins having no antitumor activity induced less IL-beta. This study indicates that oligomeric ellagitannins, which consist of tellimagrandin I or II, casuarictin or their related structure units, have antitumor activity and induce IL-1 beta.

Growth of human tumor xenografts in nude mice and mice with severe combined immunodeficiency (SCID)

Twenty-three fresh tumor specimens obtained at surgery and 5 serially transferable human tumor xenografts were implanted subcutaneously into nude mice and mice with severe combined immunodeficiency (SCID) to compare the take rates of the fresh surgical specimens and the growth rates of the transferable strains. The overall take rates were 65% for the SCID mice and 60% for the nude mice, without any significant difference, although colon carcinoma seemed to have higher acceptance in the SCID mice with a take rate of 6/8. All the serially transferable strains were successfully accepted in the SCID mice, their growth rates being essentially identical to those in the nude mice. These results indicate that the SCID mouse can be used as a human tumor xenograft-mouse system as well as the nude mouse.

Antitumor activity of oenothein B, a unique macrocyclic ellagitannin

The antitumor effect of oenothein B, a macrocyclic ellagitannin from Oenothera erythrosepala Bordas, on rodent tumors was studied. Oenothein B exhibited a strong antitumor activity against MM2 ascites tumors upon intraperitoneal administration to the mice before or after the tumor inoculation. The tannin also inhibited the growth of Meth-A solid type tumor in mice. This antitumor effect of the tannin could not be attributed to its direct cytotoxic action on tumor cells, because the cytotoxicity was very weak in the presence of serum protein. When oenothein B was injected into the peritoneal cavity of mice, peritoneal exudate cells, including cytostatic macrophages, were induced. Furthermore, in the in vitro treatment of macrophages from mice and humans, the tannin stimulated release of an interleukin 1 (IL-1)-like activity and IL-1 beta from the cells. These results suggest that oenothein B exerts its antitumor effect through potentiation of the host-immune defense via activation of macrophages.

Implication of ATP released from atrial, but not papillary, muscle segments of guinea pig by isoproterenol and forskolin

Effects of isoproterenol and forskolin, which increases intracellular cyclic AMP, on contraction and ATP release in atrial and papillary muscles of guinea pig were evaluated. In the electrically driven-left atrial muscle segments, isoproterenol and forskolin at 0.1 microM produced an ATP release coupled with a positive inotropic effect, the values of net ATP release at 5 min after these drugs being 5.20 +/- 0.59 and 5.37 +/- 0.55 nmoles/g wet weight, respectively. The forskolin evoked-ATP release was unaffected by prazosin plus propranolol or by guanethidine, implying that ATP is released from non-neuronal origin. In contrast, in papillary muscle segments, the test cardiotonics did not elicit any ATP release despite producing contractile response similar to that in atrial preparations. However, there is no difference in ectoATPase activities of both tissues. Adenosine added exogenously inhibited electrically evoked-contraction of the atrium, but not that of the papillary, although inhibitions by verapamil of the contractions were approximately equal in these preparations. These findings suggest that cardiotonics such as isoproterenol produce a liberation of ATP from auricle muscles, but not from ventricle muscles, and that the liberated ATP may mainly be catabolized to adenosine by ectoenzymes and the resultant nucleoside may serve as a functional modulator through stimulation of pre or postsynaptic A1-receptors.

An infant with both autoimmune neutropenia and idiopathic thrombocytopenia with IgG2/IgA deficiency

We report an infant with autoimmune neutropenia (AIN), idiopathic thrombocytopenia (ITP), and IgG2/IgA deficiency. The patient was referred to our hospital at 5 months of age because of epistaxis and generalized petechiae. Physical examination revealed moderate hepatosplenomegaly. A complete blood count revealed a platelet count of 2.0 x 10(3) cells/microliters, and a white cell count of 3,600 cells/microliters, with severe neutropenia (less than 1% bands and segmented cells). Neutrophils and platelets adhering to megakaryocytes were decreased in the bone marrow. Tests for serum neutrophil-binding IgG (NB-IgG) and platelet-associated IgG (PA-IgG) were positive. A diagnosis of both AIN and ITP was made and therapy with intact-type gamma-globulin and prednisolone was initiated. Improvement occurred, but was temporary. A lack of serum IgA and IgG2 was noted during the clinical course. The patient has not been susceptible to bacterial infections but has had a severe clinical course with rubella and chickenpox.

Experimental and clinical studies on the intraperitoneal administration of cis-diamminedichloroplatinum (II) for peritoneal carcinomatosis caused by gastric cancers

The effectiveness of the intraperitoneal administration of cis-diamminedichloroplatinum (II) (DDP) on peritoneal carcinomatosis caused by gastric cancers was evaluated. Seventeen patients were treated with one of three protocols, consisting of the intraperitoneal injection (ip) of DDP at doses of 70 and 110 mg/m2, with or without sodium thiosulfate (STS) rescue. The area under the curve (AUC) of DDP for sufficient anticancer activities against cultured human cell lines in vitro was estimated at 240 micrograms h/ml, which was equivalent to the AUC gained by 110 mg/m2 ip DDP in the clinical studies. The cytotoxic activity of DDP was reduced by approximately 50% with 100-fold STS in the AUC in the experimental studies. However, this was achieved only in urine, and not in either the peritoneal cavity or in plasma in the clinical studies. Three cases of a partial response against peritoneal carcinomatosis were seen from a total of four evaluable cases treated with 110 mg/m2 DDP, and no renal toxicities were observed in those treated with the STS rescue. The results of this study led us to conclude that high-dose ip DDP treatment combined with the STS rescue would be useful chemotherapy against peritoneal carcinomatosis caused by gastric cancers.

A suitable model for experimental liver metastasis of human colon cancer xenografts using mice with severe combined immunodeficiency

Studies on liver metastasis of human colon cancer are limited because of a lack of suitable animal models. In this study, the usefulness of mice with severe combined immunodeficiency (SCID), which congenitally lack functional T and B lymphocytes, was evaluated in comparison with currently available nude mice. Three human colon cancer xenografts transplantable into nude mice were disaggregated enzymatically to obtain tumor cell suspensions, and implanted intrasplenically into SCID and nude mice. The incidence of splenic tumorigenesis and of liver metastases were significantly greater in SCID mice for all xenografts, in comparison with nude mice. In total, 33 of 36 SCID mice and 17 of 43 nude mice developed liver metastases. On the basis of this result, we conclude that SCID mice would be a more suitable model than nude mice for studying liver metastasis of human colon cancer.

Role of adrenergic neuronal activity in the yawning induced by tacrine and NIK-247 in rats

The present experiments were performed to investigate the potential role of central adrenergic neurons in regulating occurrence of yawning in rats. Intraperitoneal injection of tacrine (THA) or 9-amino-2,3,5,6,7,8-hexahydro-1H-cyclopenta(b)-quinoline monohydrate HCl (NIK-247), cholinesterase inhibitors, induced yawning, which was markedly increased by pretreatment with the beta-adrenoceptor antagonist, pindolol. The yawning evoked by tacrine or NIK-247 given alone or in combination with pindolol was inhibited by pretreatment with scopolamine but not by mecamylamine or spiperone. Treatment with tacrine or NIK-247 increased acetylcholine content of the striatum, but this effect was not enhanced by pindolol, which per se did not affect basal acetylcholine content. Moreover, pretreatment with the central adrenaline synthesis inhibitors, (+-)-2,3-dichloro-alpha-methylbenzylamine HCl (LY-78335) and 2-cyclooctyl-2-hydroxyethylamine HCl (UK-1187A), increased tacrine-induced yawning. Subcutaneous injection of talipexole (B-HT 920), a dopamine D2 receptor agonist, evoked yawning, which was also increased by pindolol, LY-78335, and UK-1187A. These receptors antagonists and synthesis inhibitors per se did not cause yawning responses. The results suggest that the beta-adrenoceptor blockade and the inhibition of adrenaline synthesis facilitate the occurrence of yawning induced by cholinergic and dopaminergic agonists, and thus the central adrenergic neuronal systems may be implicated in the regulation of yawning responses.

[MR imaging of stereotactic thalamotomy using radiofrequency methods]

Sixty-eight stereotactic radiofrequency (rf) thalamic lesions in 57 patients with movement disorders were evaluated by magnetic resonance (MR) imaging. Postoperative periods ranged from 5 days to 4 years and 9 months. All 68 rf lesions were clearly detected on T2-weighted images (T2WI). Changes in signal intensity on T2WI were classified into five patterns, as follows: Pattern I: lesions with three concentric zones consisting of an inner hypointense, middle hyperintense and outer hypointense zone (31 lesions); Pattern II: lesions consisting of an inner hypointense and outer hyperintense zone (4 lesions); Pattern III: lesions consisting of an inner hyperintense and outer hypointense zone (27 lesion); Pattern IV: lesions of a hyperintense area alone (2 lesions); Pattern V: lesions of a hypointense area alone (4 lesions). The outer hypointense rim in Patterns I and III is thought to represent hemosiderin deposition. The abnormal signal intensity on T2WI caused by rf ranged from 2 to 12 mm in diameter, and lesions in the late phase were smaller than lesions in the early phase.

Endothelin-1 enhances calcium entry through T-type calcium channels in cultured neonatal rat ventricular myocytes

Endothelin-1 (ET-1), a 21-amino acid vasoconstrictive peptide, increases intracellular Ca2+ level and has hypertrophic action on ventricular myocytes. To elucidate a possible role of Ca2+ entry through sarcolemmal Ca2+ channels on this ET-1 action, we examined effects of ET-1 on L-type (ICa,L) and T-type (ICa,T) Ca2+ currents in cultured neonatal rat ventricular myocytes using the patch-clamp technique. ET-1 at a concentration of 10 nM increased the maximum current density of ICa,T from -3.0 +/- 1.4 microA/cm2 in the control condition to -4.4 +/- 1.6 microA/cm2 (p < 0.01). Although the peak amplitude of ICa,L was decreased during ET-1 application (from -9.7 +/- 1.9 microA/cm2 in the control condition to -5.0 +/- 1.4 microA/cm2 [p < 0.01]), this magnitude of decrease in ICa,T (52 +/- 19%) was comparable to that of spontaneous "run-down" of ICa,L (47 +/- 26%). The enhancement of ICa,T by ET-1 was dose dependent; it was initiated as low as 0.32 nM, and the maximal response was attained at approximately 10 nM, with a half-maximal dose of 1.26 nM. The enhancement of ICa,T by ET-1 was antagonized by protein kinase C inhibitors staurosporine (0.2 microM) and 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7, 20 microM) applied to the pipette solution. Extracellular application of tumor-promoting phorbol esters, phorbol 12,13-dibutyrate (PDBu) and 4 beta-phorbol 12-myristate 13-acetate, augmented ICa,T. PDBu (0.2 microM) increased the maximal current density of ICa,T from -4.2 +/- 0.5 microA/cm2 in the control condition to -5.5 +/- 1.0 microA/cm2 (p < 0.01). In the presence of H-7 (20 microM) in the pipette solution, PDBu failed to enhance ICa,T, and an inactive isomer of PDBu (4 alpha-phorbol 12,13-dibutyrate, 0.2 microM) did not augment ICa,T. Thus, ET-1 enhances Ca2+ entry through the sarcolemmal T-type Ca2+ channel, possibly through a pathway involving activation of protein kinase C. This ET-1 action may be involved in the rise of the intracellular Ca2+ level and may contribute to the induction of cardiac hypertrophy by ET-1.

Exhaustive physical exercise causes oxidation of glutathione status in blood: prevention by antioxidant administration

We have studied the effect of exhaustive concentric physical exercise on glutathione redox status and the possible relationship between blood glutathione oxidation and blood lactate and pyruvate levels. Levels of oxidized glutathione (GSSG) in blood increase after exhaustive concentric physical exercise in trained humans. GSSG levels were 72% higher immediately after exercise than at rest. They returned to normal values 1 h after exercise. Blood reduced glutathione (GSH) levels did not change significantly after the exercise. We have found a linear relationship between GSSG-to-GSH and lactate-to-pyruvate ratios in human blood before, during, and after exhaustive exercise. In rats, physical exercise also caused an increase in blood GSSG levels that were 200% higher after physical exercise than at rest. GSH levels did not change significantly. Thus, both in rats and humans, exhaustive physical exercise causes a change in glutathione redox status in blood. We have also found that antioxidant administration, i.e., oral vitamin C, N-acetyl-L-cysteine, or glutathione, is effective in preventing oxidation of the blood glutathione pool after physical exercise in rats.

The mucus-hypersecreting tumor of the pancreas. Development and extension visualized by three-dimensional computerized mapping

BACKGROUND

Mucus-hypersecreting tumor of the pancreas appears as dilated ducts and cystic spaces filled with mucus. To determine where such tumors arise and how they extend, computer-aided three-dimensional reconstruction was done of the ductal system. This also was used to visualize the spatial relationships among epithelial hyperplasia, dysplasia, and carcinoma in situ (CIS).

METHODS

Surgically removed pancreases were studied from 12 patients with mucus-hypersecreting tumors. The specimens were fixed in buffered formaldehyde solution 10%, embedded in paraffin and semiserially sectioned at 3 microns at an interval of 60 microns. The ductal contours were differentiated among ducts lined by ordinary epithelia, hyperplastic epithelia, dysplastic cells, or CIS and were inputted into a computer system that integrated a three-dimensional image of ducts in the display.

RESULTS AND CONCLUSIONS

(1) The tumors arose in the main pancreatic duct or its subbranches, and the cysts corresponded to segments expanded by the superficial growth of tumor cells; (2) areas of CIS arose in zones of preceding dysplasia, suggesting a dysplasia-carcinoma sequence; and (3) dysplastic or cancerous cells often extended intraductally over the dilated segments of ducts.

In vitro purging of clonogenic leukemic cells from human bone marrow by heat: simulation experiments for autologous bone marrow transplantation

In order to apply a simple purging method by heat to autologous bone marrow transplantation (ABMT), we have revaluated the ability to purge clonogenic leukemic cells from the simulated marrow mixture of normal marrow cells and leukemic cell lines (HL-60, Molt-3 and HEL) in vitro by heat, using two different clonogenic assays for normal granulocyte-macrophage progenitors (CFU-GM) and leukemic cell lines. It appeared that in vitro hyperthermia (42 degrees C for 120 min) is able to selectively remove clonogenic leukemic cells from simulated tumor cell-normal marrow mixtures even when leukemic cell concentrations are increased up to 3 x 10(6) cells/ml in vitro, and results in a 4-6 log destruction of clonogenic leukemic cells/ml according to a limiting dilution assay, while leaving half of normal CFU-GM surviving. The hyperthermic purging of clonogenic leukemic cells was not affected in the presence of normal marrow cells in vitro. This high level of clonogenic leukemic cell depletion by heat correlated with that of immunologic and pharmacologic studies. These results suggest that in vitro hyperthermia could be applied effectively and safely for the elimination of residual clonogenic leukemic cells in autologous marrow grafts before ABMT.

Tongue cancer treated with irradiation: assessment with MR imaging

We examined the usefulness of MRI in differentiating post-radiation scar tissue from the residual tumour. Ten consecutive patients who underwent MR imaging before and after radiation therapy were assessed prospectively. T1- and T2-weighted images using a 1.5 unit were obtained in 10 patients (3 T1, 6 T2, 1 T3) at 1 week before irradiation, and 2 weeks, 2 months, 4 months, 6 months and every 6 months thereafter following completion of radiation. Although all T2 and T3 tumours demonstrated high signal intensity compared to muscle on T2-weighted images, the T1 tumour could be demonstrated in only one of three patients. Six patients in whom the primary tumour clinically disappeared demonstrated low signal intensity on T2-weighted images until 4 months after completion of radiation therapy (range 1 week to 4 months). This study suggests that MRI can detect primary tumours larger than T2 (2 cm), and may be useful in assessing the effectiveness of therapy for tongue cancer.

Ribosomal protein P2, a novel iron-binding protein

We examined the properties of a new iron-binding protein purified previously from rat liver (T. Furukawa, S. Taketani, H. Kohno, and R. Tokunaga, 1991, Biochem. Biophys. Res. Commun. 181, 409-415). The protein was digested with trypsin and the peptides were analyzed by reverse-phase high-performance liquid chromatography. The partial amino acid sequences of the tryptic peptides coincided with that of rat ribosomal protein P2. Immunoblot analysis and iron-binding assay confirmed that the iron-binding protein and ribosomal protein P2 are identical. Then the iron binding ability of ribosomal protein P2 was examined in rat hepatoma H4IIEC3 cells incubated with radioactive iron. When immunoprecipitation with anti-iron-binding protein serum was performed using cells incubated with 59Fe-citrate, about 4% of the 59Fe radioactivity in cells was associated with the iron-binding protein through 30 to 90 min of incubation. About 1.5% of radioactive iron in cells incubated with 59Fe-transferrin was found in immunoprecipitates with anti-iron-binding protein serum during 1 to 5 h of incubation, and 4 to 7% of the radioactivity was found in immunoprecipitates with a monoclonal antibody against ribosomal P proteins in the same incubation. These results demonstrate that ribosomal proteins P2 binds iron taken up by the cells.

Targeting cancer chemotherapy using a monoclonal antibody (NCC-LU-243) conjugated with mitomycin C

Two kinds of immunoconjugate (T-3M and T-11M) of murine monoclonal antibody with mitomycin C (MMC) were developed using spacers containing a disulfide (T-3M) or thiocarbamate (T-11M) bond. A murine monoclonal antibody (NCC-LU-243) raised against a human small cell lung carcinoma cell line, Lu-24, in nude mice, is an IgG2a monoclonal antibody that recognizes a 145-kDa protein on the cell surface membrane. T-3M and T-11M showed affinity for the LU-243 antigen-positive H-69 cell line but not for the antigen-negative Lu-65 cell line in vitro. In the in vitro MTT assay, the order of efficacy of these compounds was T-11M > T-3M > MMC against antigen positive H-69 and T-11M = MMC > T-3M against antigen-negative K562. When antigen-positive H-69 was transplanted into nude mice for in vivo assay, the maximum tolerated dose of T-3M was twice as high than that of the parent compound MMC. Furthermore, T-3M showed higher antitumor activity against antigen-positive H-69 than MMC conjugated with a non-specific rabbit IgG in vivo. When the maximum tolerated doses of T-3M and MMC were administered to H-69-bearing nude mice, the effect of T-3M was superior to that of MMC, whereas no differences were observed between the antitumor activity of T-3M and MMC against antigen- negative MX-1, a human breast carcinoma. These two immunoconjugates of monoclonal antibody with mitomycin C are thought to be useful for targeting cancer chemotherapy against human small cell lung carcinomas.