Solvent magnetization artifacts in high-field NMR studies of macromolecular hydration

With the use of high magnetic fields and improved quality factor ratings of the probeheads in modern NMR spectrometers, radiation damping becomes more and more important. In addition, the demagnetizing field effect from protonated solvents gains significance with the increase of the magnetic field strength. During a typical NMR pulse sequence the magnetic fields caused by these effects become time-dependent, which makes the system nonlinear and may, for example, measurably influence the precession frequencies of all nuclei in the sample. Since radiation damping can affect signals that are several kilohertz away from the solvent resonance, the amplitude, phase, and frequency of the desired signals can be disturbed so as to give rise to spectral artifacts. In particular when difference methods are used to obtain the final spectrum, the data sets may be severely deteriorated by such artifacts. This paper investigates effects from the demagnetizing field and from radiation damping with a selection of pulse sequences in use for studies of macromolecular hydration, and strategies are described for the detection and elimination of the ensuing artifacts.

Protective effect of passive immunization against TNF-alpha in mice infected with Sendai virus

TNF-alpha has been reported to be induced in mice infected with Sendai virus. We evaluated the role of TNF-alpha in the virus infection. TNF-alpha was induced locally in proportion to virus titers in the lung. The activity was correlated with suppression of body weight gain. Passive immunization against TNF-alpha improved body weight gain and ameliorated pneumonic lesions in infected mice, and prevented them from lethal infection, but lung virus induced emaciation, pneumonic lesions and death were mediated by TNF-alpha.

Effect of phospholipids on adsorption and penetration of human T-cell leukemia virus type I

We have studied the ability of some phospholipids (PLs) and phospholipases (PLases) to interfere with infection of human T-cell leukemia virus type I (HTLV-I). Plating of pseudotype of vesicular stomatitis virus (VSV) bearing envelope antigens of HTLV-I, VSV(HTLV-I), was markedly inhibited by treatment of the cells with cardiolipin (CL) after, but not before, infection. Treatment of the cells with CL after infection also inhibited the plating of VSV pseudotype of bovine leukemia virus (BLV), but scarcely affected VSV infection. Furthermore, the plating of VSV(HTLV-I) was markedly enhanced by treatment with PLCase after infection. Treatment with PLCase, however, did not affect the plating of VSV. These results were also confirmed by polymerase chain reaction (PCR): Formation of proviral DNA was inhibited when indicator cells were treated with CL after cell-free infection of HTLV-I, but not before, and enhanced when indicator cells were treated with PLCase after HTLV-I infection. These findings suggested that PLs might play a role at the early stage of HTLV-I infection.

Usefulness of novel imaging modalities in diagnosis of focal nodular hyperplasia of the liver

A 17-year-old woman was admitted because of a liver tumor found incidentally by ultrasonography. Liver function was normal and there were no markers of hepatitis viruses or malignancy. Abdominal ultrasonography, computed tomography (CT), and magnetic resonance imaging revealed a mass (2 cm in diameter) in the lateral segment of the left lobe of the liver. The lesion was not detected by hepatic arteriography. However, dynamic CT with fast scanning and dynamic CO2-enhanced ultrasonography demonstrated initial central enhancement of the mass followed by centrifugal spread of enhancement to the periphery. Color Doppler flow imaging detected a central color spot, shown to be an artery by a pulsed Doppler spectrum analysis. Fine-needle biopsy confirmed a diagnosis of focal nodular hyperplasia. Dynamic CT with fast scanning, dynamic CO2-enhanced ultrasonography, and color Doppler flow imaging were useful in detecting the vascular pattern specific to focal nodular hyperplasia. Investigation of further cases with these novel imaging modalities should help to establish a comprehensive diagnostic procedure and thus avoid unnecessary surgery for focal nodular hyperplasia, which is a completely benign lesion.

Sarcoidosis accompanied by pleural effusion and multiple bronchial stenoses

Diffuse parenchymal infiltrates in lower lung fields, right pleural effusion, multiple bronchial stenoses and hepatosplenomegaly were observed in a 30-year-old woman with iritis. Pleural effusion was a yellow exudate which was predominantly lymphocytic. A pulmonary function test showed an obstructive pattern, and multiple bronchial stenoses were observed on bronchoscopy. Both transbronchial lung biopsy (TBLB) and bronchial mucosal biopsy failed in demonstrating non-caseating granulomas, but liver biopsy revealed granulomas consistent with sarcoidosis. This is a very rare case, in which pleural effusion and bronchial stenoses occurred in the same patient.

Detection of interleukin-1 and interleukin-6 on cryopreserved bovine mammary epithelial cells in vitro

This investigation was performed to determine whether primary cultures of mammary cells from lactating cows would sustain production of interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF), and express mRNA for cytokines interleukin (IL)-1alpha, IL-1beta, IL-2, IL-4, IL-6, IL-10, interferon (INF)-tau, TNF-alpha, and granulocyte-macrophage colony-stimulating factor (GM-CSF) by the reverse transcription-polymerase chain reaction (RT-PCR) in vitro. Cryopreserved mammary epithelial cells collected from cows at 1 week post calving were plated in collagen-coated 24-well culture plates (250,000 cells/well). IL-1 and IL-6 productions were measured using a A375 cell growth inhibition assay and a 7TD1 hybridoma proliferation assay, respectively. Production of IL-1 was demonstrated in mammary epithelial cells cultured with unsupplemented medium, but was not produced by cells cultured in medium supplemented with fetal bovine serum. IL-6 production in the conditioned medium was continued at steady level until day 14, whereas IL-6-like bioactivity was not detected in medium alone. TNF-like activity was not detectable in any experiments. This study also demonstrated the expression of mRNA for multiple cytokines including IL-1alpha, IL-1beta, IL-6, IL-10, TNF-alpha, and GM-CSF by RT-PCR in mammary cell cultures. The results indicate that bovine mammary epithelial cells of lactating cows produce IL-1 and IL-6 and have gene expression for multiple cytokines. This in vitro model will be useful to investigate the function and regulation of IL-1 and IL-6 in the lactating mammary gland.

Anisotropic molecular rotational diffusion in 15N spin relaxation studies of protein mobility

The backbone dynamics of the uniformly 15N-labeled N-terminal 63-residue DNA-binding domain of the 434 repressor has been characterized by measurements of the individual 15N longitudinal relaxation times, T1, transverse relaxation times, T2, and heteronuclear 15N[1H]-NOEs at 1H resonance frequencies of 400 and 750 MHz. The dependence of an apparent spherical top correlation time, tauR, on the orientation of the N-H bond vector with respect to the principal axes of the global diffusion tensor of the protein was used to establish the fact that the degree of anisotropy of the global molecular tumbling amounts to 1.2, which is in good agreement with the values obtained from model calculations of the hydrodynamic properties. A model-free analysis showed that even this small anisotropy leads to the implication of artifactual slow internal motions for at least two residues when the assumption of isotropic global motion is used. Additional residues may actually undergo internal motions on the same time scale as the global rotational diffusion, in which case the model-free approach would, however, be inappropriate for quantifying the correlation times and order parameters. Overall, the experiments with 434(1-63) demonstrate that the assumption of isotropic rotational reorientation may result in artifacts of model-free interpretations of spin relaxation data even for proteins with small deviations from spherical shape.

Detection of interleukin-1 beta in sera and colostrum of dairy cattle and in sera of neonates

In order to obtain basic information about bovine interleukin-1 (IL-1 beta), levels of IL-1 beta in sera and milk of clinically normal mature Holstein cattle before and after parturition and in sera of newborn calves were examined by ELISA. The level of IL-1 beta was undetectable in sera of mature cattle around the time of artificial insemination, but the concentration gradually increased and reached a peak at parturition and then decreased again to an undetectable level. IL-1 beta in milk was detected on the day of parturition but not thereafter. IL-1 beta mRNA was detected by reverse transcription-polymerase chain reaction in the cells from milk collected during 20 days before and 2 to 3 days after parturition, but was not detected thereafter. Although IL-1 beta was not detected in all the sera of newborn calves, the concentration transiently increased with peak titers on day 3 and became undetectable by day 14 after birth. Newborns that showed serum IL-1 beta on day 3 had been fed on colostrum in which the IL-1 beta concentration was significantly higher than that in colostrum that had been fed to newborns having no detectable IL-1 beta on day 3. These results indicate that IL-1 beta is induced in association with pregnancy in healthy dairy cattle and that the cytokine might be transferred to neonates via colostrum.

Effect of histamine on intracellular Ca2+ concentration in guinea pig isolated vestibular hair cells

The present study examined the effects of histamine in the guinea pig isolated vestibular hair cells (VHCs) by measuring the dynamic changes of intracellular free calcium ion ([Ca2+]i) concentration using calcium sensitive dye Fura-2. The histamine-induced calcium response in VHCs was markedly increased at the concentration of 10 microM histamine in the presence of extracellular Ca2+, while in the absence of extracellular Ca2+, a slow increase of [Ca2+]i was evident. Receptor specificity of the response to histamine was examined: promethazine (H1 receptor antagonist), cimetidine (H2 receptor antagonist) and thioperamide (H3 receptor antagonist) completely blocked the histamine-induced calcium response at the concentrations of 2.5 microM, 1.0 microM and 1.0 nM, respectively. The responses were mediated by H1, H2 and H3 receptors and resulted in a rise of [Ca2+]i due to an influx of Ca2+ from the extracellular space and a release from intracellular stores. Our preliminary data suggest that under immuno-pathological conditions of the inner ear, histamine released from the mast cells distributed in the endolymphatic sac may act through receptors located on the vestibular hair cell membrane and may regulate the cell function and the signal transduction in the vestibular nerve-hair cell afferent system.

Anionic sites of charge barrier in the guinea pig crista ampullaris

In present studies we obtained anionic sites in the epithelial and capillary basement membranes in the dark cell area of the crista ampullaris in the guinea pig. The immersion method with cationic tracer polyethyleneimine (PEI) was applied. Electronmicroscopically, the arrangement of PEI particles was observed as two strata along the basement membrane. The number of particles could be counted and compared in each portion. The control test with protamine sulfate showed that the number of PEI particles decreased in both the epithelium and capillaries of the dark cell area. In the experiment using furosemide, the stria vascularis and the dark cells had changed, with pathological findings of interstitial edema and PEI particles reduced in number. It is suggested that the PEI particles reflect different conditions of charge in the basement membrane, which influences the production or absorption of the inner ear fluid.

[Study of malignant lymphoma in the parotid gland region]

Malignant lymphomas arising in the salivary glands are very uncommon. The vast majority of these lesions are classified as extranodal non-Hodgkin's lymphoma. Clinical presentation, management, histopathology, and outcome in 11 cases of non-Hodgkin's lymphomas of the parotid gland region were reviewed. The ages of the patients ranged from 25 to 80 years (average 56.0 years) and the male to female ratio was 5:6. Presenting symptoms were painless masses (10 cases) and a painful mass (1 case) in the parotid gland region. None of the patients had facial nerve paralysis. It seems to be difficult to diagnose malignant lymphomas of the salivary glands preoperatively, because an open biopsy of the salivary glands is generally contraindicated. We failed to diagnose malignant lymphoma in the parotid gland preoperatively. The clinical stages were stage I in 5 cases, stage II in 5 cases, and stage III in 1 case. There was no patient with stage IV. Three of the stage I tumors were diagnosed as MALT (mucosa-associated lymphoid tissue) lymphomas. Eight of the tumors were treated surgically and an open biopsy of the parotid gland tumor was performed in 1 case and open biopsy of a neck lymph node in 2 cases for the purpose of diagnosis. After the diagnosis, these cases were followed up with or without radiotherapy and chemotherapy. Follow-up ranged from 6 to 109 months. The 5-year-survival rate was 60%. The outcome for this group was found to be as good as that reported by others.

The usefulness of MR in establishing the diagnosis of parotid pleomorphic adenoma

PURPOSE

To assess the usefulness of MR findings in establishing a specific diagnosis of parotid pleomorphic adenoma.

METHODS

T1-weighted and T2-weighted MR images with and without contrast enhancement were obtained in 82 patients with parotid tumors. Imaging findings in the 38 patients in whom surgery subsequently revealed pleomorphic adenomas were compared with findings in the 44 patients who had other types of tumor. Specifically, the homogeneity, signal intensity, contrast enhancement, capsule thickness, lobulation, adenopathy, and infiltration of adjacent fat were compared among the different types of tumor. The sensitivity, specificity, positive predictive value, and negative predictive value were calculated.

RESULTS

A low-signal capsule on T2-weighted images and a lobulated contour characterized most pleomorphic adenomas. The sensitivity of the first finding for pleomorphic adenoma was 82%; specificity, 85%; positive predictive value, 82%; and negative predictive value, 84%. For the second finding, the sensitivity was 53%; specificity, 84%; positive predictive value, 74%; and negative predictive value, 67%.

CONCLUSION

None of the signs evaluated had perfect sensitivity and specificity. The MR findings of a complete capsule, lobulated contour, or high T2 signal intensity have a high predictive value for the diagnosis of pleomorphic adenoma.

Identification and purification of a novel phospholipid/ganglioside-binding protein in rabbit serum

We have isolated a novel phospholipid/ganglioside-binding protein from rabbit sera or platelet-free plasma. Using an affinity chromatography of a commercial gel (Sephacryl S-series gel, Pharmacia) column and a preparative polyacrylamide gel electrophoresis, the protein can be easily purified. The protein agglutinates human red cells irrespective of the ABO blood types, and its hemagglutination reaction is specifically inhibited by some phospholipids (phosphatidylserine and phosphatidylglycerol) and ganglioside (N-acetylneuraminyl-galactosylglucosyl ceramide, GM3). The hemagglutination and its inhibition reactions are independent on any divalent cations (Ca2+, Mg2+, Mn2+, Ni2+). The protein seems to be assembled as multimers of disulfide-bonded molecular of 86 kDa and 59 kDa subunits.

Growth and protective potentials of attenuated strains of equid herpesvirus 1 in the lungs of mice

Attenuated equid herpesvirus 1 (EHV-1) strains with different passage histories in bovine kidney cells (BKC), i.e. BK77, BK161, BK271 and BK343, were examined for their growth in mouse lungs after intranasal inoculation. BK77 and BK161 were recovered from lungs with almost the same titres, and were found to be about 100 times lower than that of the parent HH1 strain. The growth abilities of high-passaged BK271 and BK343 were markedly reduced. Although partial growth of BK343 in the lungs of athymic nude mice was observed, the virus was almost eradicated from their lungs within 1 week. By contrast, the parent HH1 persisted in the lungs of nude mice for at least 1 week. The mice immunized with the BKC-passaged viruses were partially protected against subsequent challenge with the parent HH1. Antibodies were detected by ELISA. These results demonstrate that, although serial BKC-passage lowered the growth ability of the parent HH1, the descendant viruses still have a partial protective potential in mice.

Optical isomers of a new 2-nitroimidazole nucleoside analog (PR-350 series): radiosensitization efficiency and toxicity

PURPOSE

A new 2-nitroimidazole nucleoside radiosensitizer, PR-350 (1-[1',3',4'-trihydroxy-2'-butoxy]-methyl-2-nitroimidazole), has been reported to be as efficient as and less toxic than etanidazole. This compound is racemic, and it was recently optically resolved into two isomers, PR-68 (2'R,3'S type) and PR-69 (2'S,3'R type). The other two isomers, PR-28 (2'S,3'S type) and PR-44 (2'R,3'R type), were asymmetrically synthesized. In the present study, we investigated the properties, sensitizing activity, and toxicity of PR-350 and the four optical isomers in comparison with those of other 2-nitroimidazole hypoxic cell radiosensitizers, etanidazole, KU-2285, KIN-804, and RP-170. Because PR-350 and PR-28 can be industrially synthesized, we evaluated whether either of these two drugs are suitable for further investigation.

METHODS AND MATERIALS

In an in vitro study, EMT-6 cells were irradiated at a dose of 1-3 Gy under hypoxic conditions in the presence of the drugs at a concentration of 1 mM. A combined cytokinesis-block micronucleus and chromosomal aberration assay was performed. To assess the in vivo effects, colony assay and growth delay assay were performing using SCCVII tumor-bearing C3H mice. The mice received 16-24 GY 10-40 min after administration of 50-200 mg/kg of the drugs. Toxicity and pharmacokinetics in mice were also investigated.

RESULTS

The sensitizer enhancement ratio (SER) in the in vitro cytokinesis-block micronucleus assay increased in the following order: PR-69 (1.27) approximately equal to PR-28 (1.31) approximately equal to PR-44 (1.38) approximately equal to PR-350 (1.41) approximately equal to PR-68 (1.47) < etanidazole (1.79) < KIN-804 (2.03) approximately equal to KU-2285 (2.30). The SER at a dose of 200 mg/kg and at an interval of 20 min (optimal interval) in the in vivo-in vitro colony assay increased as follows: PR-44 (1.26) approximately equal to PR-28 (1.29) < PR-69 (1.34) approximately equal to etanidazole (1.35) approximately equal to PR-350 (1.36) < RP-170 (1.41) approximately equal to PR-68 (1.41) < KU-2285 (1.49). The growth delay assay also showed that PR-350 was less efficient than KU-2285 and more efficient than PR-28. PR-350 and the four isomers had similar reduction potentials, but PR-28 and PR-44 were more hydrophilic than PR-68 and PR-69. The LD50 in mice were 5.8 g/kg for PR-350, approximately 7 g/kg for PR-28, 4 g/kg for PR-68, and 6 g/kg for PR-44 and PR-69. The concentration of PR-28 in the murine sciatic nerve was lower than that of PR-350.

CONCLUSION

In vivo radiosensitizing activity differed among the four optical isomers, which appeared to be due, at least in part, to differences in lipophilicity. Although PR-28 was the least toxic, its low sensitization efficiency does not warrant clinical trials. Among the PR compounds, PR-68 appears to be most efficient, but optical resolution of PR-68 from PR-350 is expensive, and asymmetrical synthesis of PR-68 is not established. Therefore, PR-350 seems to be most suitable for further investigation among the PR-350 series compounds, considering its higher efficiency compared with PR-28 and PR-44, and established synthesis.

Three-dimensional solution structure of the calcium channel antagonist omega-agatoxin IVA: consensus molecular folding of calcium channel blockers

The three-dimensional solution structure of omega-agatoxin IVA, which is a specific blocker of the P-type calcium channel isolated from funnel web spider venom and has a molecular mass of 5.2 kDa, was determined by two dimensional 1H NMR spectroscopy, combined with simulated annealing calculations. On the basis of 563 experimental constraints, including 516 distance constraints obtained from the nuclear Overhauser effect, 21 torsion angle (phi, chi 1) constraints, and 26 constraints associated with hydrogen bonds and disulfide bonds, a total of 14 converged structures were obtained. The atomic root mean square difference for the 14 converged structures with respect to the mean coordinates is 0.42 (+/- 0.07) A for the backbone atoms (N, C alpha, C) and 0.95 (+/- 0.15) A for all heavy atoms of the central part (residues 4 to 38) constrained by four disulfide bonds. The N- and C-terminal segments (residues 1 to 3 and 39 to 48, respectively) have a disordered structure in aqueous solution. The molecular structure of omega-agatoxin IVA is composed of a short triple-stranded antiparallel beta-sheet, three loops, and the disordered N- and C-terminal segments. The overall beta-sheet topology is +2x, -1, which is the same as that reported for omega-conotoxin GVIA, an N-type calcium channel blocker. Irrespective of differences in the number of disulfide bonds and low primary sequence homology, these two peptide toxins show a significant structural similarity in three dimensions. The whole-cell voltage-clamp recording using rat cerebellar slices suggests that the hydrophobic C-terminal segment of omega-agatoxin IVA, which does not exist in omega-conotoxin GVIA, plays a crucial role in the blocking action of omega-agatoxin IVA on the P-type calcium channel in rat cerebellar Purkinje cells. The present study provides a molecular basis for the toxin-channel interaction, and thereby provides insight into the discrimination of different subtypes of calcium channels.

Attempt to discriminate between bovine viral-diarrhoea virus strains using polymerase chain reaction

The polymerase chain reaction (PCR) was applied to detect bovine viral-diarrhoea mucosal-disease virus (BVDV). By the use of properly prepared primers, cytopathogenic NADL, Oregon C24V, Nose, T-20 and KS86-1(+) strains, and non-cytopathogenic New York-1, No. 12, and KS86-1(-) strains could be detected. The PCR system was applied to field isolates of the viruses. All the viruses were detected by the PCR. Four patterns of the PCR amplification were recognized, and it was possible to discriminate between some strains. These results corresponded with the serotype of BVDV, as determined by the serum-neutralizing test. The BVDV gene was detectable from the leucocytes of infected cattle using the PCR method. Moreover, it was possible to detect and discriminate BVDV strains using one PCR tube that included all primer pairs.

Evidence of cellular supplies to the endolymphatic sac from the systemic circulation

Donor T lymphocytes injected into the host systemic circulation were observed to infiltrate into the host endolymphatic sac in mice. These findings suggest that the endolymphatic sac, a major immune organ in the inner ear, is supplied with immunocompetent cells from the systemic circulation. This concept is consistent with clinical reports that inner ear disorders accompany certain systemic autoimmune diseases. Bone marrow transplantation to replace autoreactive immunocompetent cells with normal cells should be considered as a potential therapy for inner ear autoimmune diseases and an alternative to conventional treatments.

A bioassay for bovine interleukin-1 by the A375 cell growth inhibition

Usefulness of a human melanoma cell line A375 was evaluated for detecting bovine interleukin-1 (IL-1). The A375 cell growth was inhibited by culture supernatant of lipopolysaccharide-stimulated bovine peripheral blood mononuclear cells (LPSsup) in a dose dependent manner. A mixture of anti-human IL-1 alpha and beta antibodies suppressed 60% of this inhibitory activity and was confirmed to bind to about 23 k dalton peptides in the LPSsup by Western blotting. Although serum and bronchoalveolar lavage fluid from a healthy cow showed a low inhibitory activity, those from pneumonic cows showed the higher activities. These activities were also suppressed by anti-human IL-1 antibodies. These findings show the A375 cell growth inhibition assay can be a useful bioassay for bovine IL-1 (like) activity.

Activation of thymic B cells by signals of CD40 molecules plus interleukin-10

We have previously found that thymic B cells, particularly thymic CD5+ B cells, show low responsiveness to the usual B cell stimulants such as lipopolysaccharide or anti-IgM plus interleukin (IL)-4, although they proliferate and produce antibodies after direct interaction with major histocompatibility complex class II-restricted T blasts. These findings raise the possibility that a CD40-CD40 ligand (L) interaction is involved in the activation of thymic B cells. In the present study, we therefore examine this possibility using CD40L-transfected Chinese hamster ovary (CHO) cells or anti-CD40 monoclonal antibody (mAb). When B cells in the spleen and peritoneal cavity were stimulated, they proliferated and produced immunoglobulin (Ig) in the presence of CD40L-CHO cells or anti-CD40 mAb alone. However, another signal delivered by IL-10 in addition to CD40L-CHO cells or anti-CD40 mAb was found to be necessary for thymic B cells to proliferate and secrete Ig. Other interleukins acting on B cells, such as IL-4, IL-5, and IL-6, had no effect on the activation of thymic B cells, which thus have unique characteristics not found in peripheral B cells. This report discusses the physiological significance of IL-10- and CD40-driven signals in the activation of thymic B cells.

Evaluation of pertussis treatment with erythromycin ethylsuccinate and stearate according to age

Although erythromycin estolate has been fully assessed for pertussis treatment, the evaluation of erythromycin ethylsuccinate and stearate, the main erythromycin preparations used in Japan and the US, is inadequate. We evaluated these preparations to establish an appropriate treatment for pertussis according to age. Sixty-six patients with culture-confirmed pertussis were treated with erythromycin administered at a dosage of 40-50 mg/kg/day (maximum, 1.2 g/day). Negative culture was obtained in 39% (15/38) of patients aged 0-2 years within one week and in 71% (27/38) within two weeks, in 78% (7/9) of those aged 3-15 years within one week and in 100% (9/9) within two weeks. All 12 adult patients had a negative culture within one week. The efficacy of erythromycin for the eradication of B. pertussis was significantly lower in children aged 0-2 years than in older children. In conclusion, it is desirable to administer erythromycin for three weeks to children aged 0-2 years, two weeks to those aged 3-15 years and one week to adults.

Selective inhibition of dexamethasone-induced apoptosis in rat thymocytes by herbimycin A

DNA fragmentation and cell death in rat thymocytes induced by dexamethasone were inhibited by herbimycin A but not by the other inhibitors of tyrosine kinase including genistein and tyrphostin. Herbimycin A also prevented the inter-nucleosomal DNA fragmentation induced by dexamethasone. On the contrary, apoptosis induced by DNA topoisomerase inhibitors such as camptothecin and etoposide were not affected by herbimycin A. These results demonstrate that dexamethasone-induced apoptosis is specifically inhibited by herbimycin A.

Radiosensitizing activity and pharmacokinetics of multiple dose administered KU-2285 in peripheral nerve tissue in mice

PURPOSE

In a clinical trial in which a 2-nitroimidazole radiosensitizer was administered repeatedly, the dose-limiting toxicity was found to be peripheral neuropathy. In the present study, the in vivo radiosensitizing activity of KU-2285 in combination with radiation dose fractionation, and the pharmacokinetics of cumulative dosing of KU-2285 in the peripheral nerves were examined.

METHODS AND MATERIALS

The ability of three nitroimidazoles, misonidazole (MISO), etanidazole (SR-2508) and KU-2285, to sensitize SCCVII tumors to radiation treatment has been compared for drug doses in the range 0-200 mg/kg. Single radiation doses or two different fractionation schedules (6 Gy/fractions x three fractions/48 h or 5 Gy/fractions x five fractions/48 h) were used; the tumor cell survival was determined using an in vivo/in vitro colony assay. The pharmacokinetics in the sciatic nerves were undertaken, when KU-2285 or etanidazole were injected at a dose of 200 mg/kg intravenously one, two, three or four times at 2-h intervals.

RESULTS

At less than 100 mg/kg, KU-2285 sensitized SCCVII tumors more than MISO and SR-2508 by fractionated irradiation. Evaluation of pharmacokinetics in the peripheral nerves showed that the apparent biological half-life of SR-2508 increased with the increases in the number of administrations, whereas that of KU-2285 became shorter.

CONCLUSION

Since most clinical radiotherapy is given in small multiple fractions, KU-2285 appears to be a hypoxic cell radiosensitizer that could be useful in such regimens, and that poses no risk of chronic peripheral neurotoxicity.

Fluorinated 2-nitroimidazole derivative hypoxic cell radiosensitizers: radiosensitizing activities and pharmacokinetics

PURPOSE

To assess the effects of incorporation of a CF2 group into the side chain of a 2-nitroimidazole derivative, we evaluated the in vitro and in vivo radiosensitizing activities of KU-2285 (a 2-nitroimidazole derivative with an N1-substituent of -CH2CF2CONH(CH2)nOH, n = 2) and its related compounds in comparison with those of comparable nonfluorinated compounds. The pharmacokinetics of these compounds in murine tumors was also tested.

METHODS AND MATERIALS

KU-2285, KU-3202 (n = 3) and KU-3207 (n = 4) are fluorinated 2-nitroimidazole derivative compounds with similar structures. Etanidazole (a 2-nitroimidazole derivative with an N1-substituent of -CH2CONH(CH2)nOH, n = 2) and its related compounds, KU-3205 (n = 3) and KU-3206 (n = 4) were also tested. The in vitro radiosensitizing activities of each compound for hypoxic cells was evaluated with a standard colony formation method. The in vivo radiosensitizing activities of these compounds were tested in female C3H/He mice bearing SCCVII tumors using an in vivo/in vitro clonogenic assay. The pharmacokinetic studies were performed in C3H/He mice bearing the SCCVII tumor. Samples were analyzed by reverse-phase high-performance liquid chromatography.

RESULTS

The in vitro radiosensitizing activities of fluorinated 2-nitroimidazoles were higher than those of the nonfluorinated compounds. Although the in vivo radiosensitizing activity of KU-2285 was higher than that of etanidazole (p < 0.05), other fluorinated 2-nitroimidazoles showed less radiosensitizing activity than the comparable nonfluorinated compounds. The compound was eliminated from serum more rapidly with the increase in the number of CH2 group in the side chain of the compound in each series.

CONCLUSION

Although the in vitro sensitizing activity of the fluorinated compounds was higher than that of the comparable nonfluorinated compounds, the in vivo radiosensitizing activity of all fluorinated compounds but KU-2285 was lower than that of comparable etanidazole group compounds, probably due to their lower molecular concentrations in tumor and rapid elimination.