[Scavenging of probimane on semiquinone free radical formation by doxorubicin in rat heart]

Probimane, dl-bis (4-morpholin-methyl 3,5-dioxopipweazin-1-yl) propane first synthesized in China, is a dioxopiperazin compound with antineoplastic, antimetastatic and radiopotentiating activities. In order to evaluate the mechanisms of cardiotoxicity protective action of probimane, the free radical induced by doxorubicin were analysed by electron spin resonance (ESR) techniques. Our studies showed that doxorubicin stimulated the formation of semiquinone free radicals in the rat heart homogenate and heart cell mitochondria systems, and probimane inhibited the free radical formation in both systems, with the dose-dependent and time-dependent responses. The inhibitory rates of doxorubicin free radical formation in rat heart homogenate system by probimane 0.6 mmol.L-1 at time of 3, 5, 10, 15, 30, 45 and 60 min were 44.6%, 43.0%, 51.5%, 74.3%, 68.1%, 56.1% and 39.9% respectively. The inhibitory rates of semiquinone free radical formation in mitochondria system by probimane at the concentration of 0.02, 0.06, 0.6, 1.2 and 2.4 mmol.L-1 were 17.07%, 29.87%, 63.95%, 64.62% and 83.64%, respectively. Probimane had no effect on NADH2, but inhibited NADH dehydrogenase activity at higher concentration.

Diffusion of water in rhyolitic glasses

Water dehydration experiments on rhyolitic glasses have been carried out at 400-550 degrees C under a N2 atmosphere. Concentration profiles of both H2O molecules and OH groups were measured by Fourier transform infrared spectroscopy. As found in previous studies of water diffusion in rhyolitic melts, the measured total water concentration profiles do not match expectations based on a single constant diffusion coefficient for total water. The diffusion of total water is described by considering the diffusion of both H2O molecules and OH groups and the reaction between them. The concentration relationship between the two species has been obtained from direct infrared measurement on quenched experimental charges. The quench is inferred to be rapid enough to preserve concentrations of both species at experimental temperature based on experimental results designed to examine reaction kinetics. The measured species concentrations along diffusion profiles show that local equilibrium between H2O and OH is approximately reached at high temperatures and high water contents. However, at lower water content or lower temperature, local equilibrium is not reached. In treating the diffusion problem, this disequilibrium effect is partially compensated by using empirical relationships between H2O and OH concentrations based on measurements, instead of using an equilibrium relationship. It is thus possible to obtain diffusion coefficients for both species from their concentration profiles. The diffusion coefficient of OH is found to be negligible compared to that of H2O at 403-530 degrees C (DOH < 0.02 DH2O and could be much smaller); i.e., H2O is the dominant diffusing species even at total water concentration as low as 0.2 wt%. The variation of OH concentration along the diffusion profile is inferred to be due to the local interconversion between OH groups and H2O molecules; the reaction also provides the diffusing H2O species. DH20 values are found to vary by less than a factor of 2 over a total water concentration range of 0.2 to 1.7 wt%. This simple model, coupled with the assumption of local equilibrium between H2O and OH, yields a very good fit to the data from diffusion-couple experiments of LAPHAM et al. (1984) at 850 degrees C. When our data are combined with DH2O obtained from that fit, DH2O (in m2/s) is given by: ln DH2O = (-14.59 +/- 1.59) - (103000 +/- 5000) / RT; 673 K < or = T < or = 1123 K, where T is temperature in K and R is the gas constant in J K-1 mol-1. This equation also approximates well DH2O values calculated from previous measurements of concentration-dependent bulk water diffusion coefficients of KARSTEN et al. (1982). The diffusion of H2O is also compared to the diffusion of the noble gas elements. The activation energy for diffusion in rhyolitic glasses is well correlated with neutral species radii of He, Ne, H2O, and Ar. This supports the contention that the diffusing species for "water" is neutral molecular H2O. The role of speciation may also be important in understanding the diffusion of many other multi-species components, and the effect can be treated in a similar fashion as that during water diffusion.

Dilazep-induced vasodilation is mediated through adenosine receptors

Administration of dilazep, an inhibitor of adenosine uptake, significantly reduced systemic arterial blood pressure and increased superior mesenteric arterial conductance without affecting the plasma adenosine levels of femoral arterial or portal venous blood. Administration of a bolus dose of 8-phenyltheophylline (8-PT), an antagonist of adenosine receptors, blocked adenosine-mediated autoregulation of the superior mesenteric artery. After the blockade of adenosine receptors by 8-PT, dilazep did not produce vasodilation. These data suggest that dilazep has a vasodilating effect in vivo that is mediated by adenosine.

Sequence of a HeLa cDNA provides the DNA binding domain and carboxy terminus of HE47: a human helix-loop-helix protein related to the enhancer binding factor E47

In order to identify cDNA encoding regulators of gene expression, a HeLa lambda gt11 expression library was screened with a DNA segment containing multiple copies of a sequence spanning the AP4 site in the simian virus 40 control region. We identified a partial cDNA encoding HE47, a sequence-specific DNA binding protein. The HeLa clone overlaps with a previously reported human B-cell partial cDNA encoding E47. The HeLa cDNA includes the HE47 DNA binding domain, its carboxy terminus, and the 3' untranslated region of its mRNA.

Prediction of heating patterns of a microwave interstitial antenna array at various insertion depths

Measurements made on the interstitial microwave antennas used for hyperthermia cancer therapy indicate that the heating patterns vary with the insertion depths (defined as the distance from the antenna tip to air-tissue interface). The antennas are made of thin coaxial cables with a radiation gap or gaps on the outer conductor. The antennas are inserted into small polypropylene catheters implanted in the tumour volume. This type of antenna may be simulated as an asymmetric dipole with one arm being the tip section consisting of the expanded extension of the inner conductor, and the other arm being the section of the outer conductor from the gap to the insertion point (air-tissue interface). We use four of the antennas to form a 2 cm x 2 cm array. The antennas are positioned on the corners of a 2 cm square. Measurements on both single antennas and multi-antenna arrays show that the maximum heating is not stationary with position along the antenna when the depth of insertion is changed. This paper investigates the theoretical prediction of the changes in heating patterns of interstitial microwave antennas at different insertion depths. Each of the antennas in the array is simulated as an asymmetric dipole. The SAR (specific absorption rate) is computed by using the insulated dipole theory. The temperature distribution in absence of perfusion is obtained through a thermal simulation routine to convert the SAR pattern into the temperature pattern. Excellent qualitative agreement is found between the theoretical heating pattern and the measured pattern in a non-perfused phantom on a 2 cm x 2 antenna array. Since the insertion depths of the interstitial antennas are different from patient to patient, it is recommended that simulation of the heating be done before treatments, to confirm the delivery of power to the target region.

Application of cell culture toxicity tests to the development of implantable biosensors

Cell culture toxicity testing methods were modified and applied to the development of implantable glucose microsensors, and positive and negative control materials suitable for the microsensor assessment were established. The location, source and degree of the toxic effect in a multi-component biosensor was spatially visualized with cell monolayers. A freshly prepared sensor showed moderate toxicity, mainly as a result of the presence of glutaraldehyde and the residual solvents in the polymer layers. However, it was possible to reduce the toxicity by removing the leachable toxic substances through extraction in phosphate buffer, and a non-toxic sensor was readily obtained.

Heating patterns generated by phase modulation of a hexagonal array of interstitial antennas

In this paper, we investigate an array of six interstitial microwave antennas used for hyperthermia cancer treatment. The purpose is to generate both uniform and controlled nonuniform heating patterns in biological tissue by phase modulating the signals applied to each antenna. The array consists of six antennas positioned on the corners of a hexagon. The distance between two diagonal antennas is 4 cm. The distributions of absorbed power per unit mass within the array are computed, and then converted into temperature distributions through a thermal conduction simulation. The SAR and temperature patterns are presented in both the lateral plane (perpendicular to the antennas) and the axial plane (parallel with the antennas). By proper phase modulation of microwave signals applied to each antenna, a uniform heating pattern can be produced within the entire array volume. Also, a peripheral heating pattern may be generated around the array; again, by using the proper phase modulation. The modulation schemes for generating both types of heating patterns are discussed.

Diffusion of a multi-species component and its role in oxygen and water transport in silicates

An important but poorly understood factor that affects diffusion rates is the role of speciation during diffusion of a multi-species component. The diffusion of such a component is complicated by the different diffusion coefficient of each species and the interconversion reactions among the species. These complexities can be treated by a diffusion equation that incorporates the diffusive fluxes of all species contributing to the concentration of the component. The effects of speciation on the diffusion of the component can be investigated experimentally in some simple cases by measuring concentration profiles of all species developed during diffusion experiments or by studying some of their other consequences. Experimental data on water diffusion in rhyolitic glasses indicate that although dissolved water is present as two species, H2O molecules and OH groups, molecular H2O is the dominant diffusing species at very low to high water concentrations. This explains the apparently complex behavior of water diffusion. Experimental data on oxygen diffusion in some silicates using 18O tracers in the form of H2(18O) are consistent with the idea that 18O transport is dominated by diffusion of H2O molecules even at lower water contents (ppm or less). This explains why oxygen transport depends on the presence of water and generally depends on water fugacity linearly. For this mode of oxygen transport, there is a simple theoretical relationship between the effective total oxygen diffusion coefficient and the total water diffusion coefficient that is a function of only the water concentration of the silicate at low water content. This relationship appears to describe quantitatively the existing data over a wide range in water contents and diffusion coefficients in several phases.

Identification of T-cell epitopes of autoantigens using recombinant proteins; studies on experimental autoimmune myasthenia gravis

In the Lewis rat, T-cell lines from animals immunized with native or denatured Torpedo nAChR recognize the Torpedo-derived recombinant protein T alpha X1 omega (alpha-2-200) but not the equivalent mouse- or chick-derived recombinant proteins X4 omega or C alpha X1 omega (alpha 6-216 and alpha 35-216, respectively). T-cell lines derived from animals immunized with T alpha X1 omega, X4 omega or C alpha X1 omega are specific for the homologous protein. This lack of cross-species reactivity suggests caution in the use of Torpedo nAChR-selected lines generated from human patients. Proteolysis and fractionation of the products by reverse-phase HPLC was effective in localization of a T-cell epitope of X4 omega, a mouse-derived recombinant protein. With Lewis rats, the major epitope of T alpha X1 omega is alpha 97-112. However, the major epitope of the mouse-derived protein, X4 omega, as determined by proteolytic digestion and fractionation of the products by reverse-phase HPLC, is alpha 14-22. This shift in T-cell epitope between closely related proteins may result from the conservation of sequence of alpha 97-112 between mammalian species.

Immunological heterogeneity of autoreactive T lymphocytes against the nicotinic acetylcholine receptor in myasthenic patients

The response of human T lymphocytes against the nicotinic acetylcholine receptor (AChR) was studied in five patients with myasthenia gravis (MG) and in six healthy donors using either native Torpedo AChR or recombinant protein derived from the mammalian AChR alpha subunit (X4, residues 6-216 of mouse AChR alpha subunit). The present study demonstrates that (a) AChR-specific T helper cell lines can be generated from MG patients [either from peripheral blood lymphocytes (PBL) or from thymocytes] as well as from PBL of normal controls, (b) lymphocytes from MG patients, but not from controls, recognize the mammalian AChR but not the Torpedo receptor, (c) in humans, the HLA-DR2-associated T cell epitope is probably located in the region of residues 162-216 of the AChR alpha subunit and (d) there is a considerable heterogeneity of autoreactive T cell responses: (i) T cell lines from different HLA-type donors have distinct epitope profiles; (ii) the epitope specificity of the PBL-derived T cell line is different from that of the thymocyte-derived line; (iii) the epitope specificities of patient-derived T cell lines are different from those generated from normal controls who share the same HLA phenotype.

[The augmenting effect of selenium(Se) on cell-mediated immunity. III. Se enhances delayed-type hypersensitivity reaction by promoting antigen presentation]

Delayed-type hypersensitivity reaction (DTH) to TNCB in TNCB-primed mice was increased when mice was treated with sodium selenite. In vitro studies showed that primed T cells proliferated more vigorously when TNP-conjugated spleen adherent cells (SAC) from Se-treated mice were the stimulators as compared with SAC of untreated controls. TNP-conjugated SAC treated in vitro with sodium selenite were even stronger stimulators than SAC treated in vitro. The results indicate that Se enhances DTH by promoting antigen presentation.

[Antimutagenicity screening of water extracts from 102 kinds of Chinese medicinal herbs]

Our observation shows that out of 102 kinds of Chinese medicinal herbs tested, 17 have remarkable antimutagenic effect on the mutation induced by aflatoxin B1, in Ames test. Among the 17 herbs Glycyrrhiza uralensis, Bupleurm chinense, Portulaca grandiflora and Cnidium monnieri have been found in other tests to be effective against mutagenesis induced by cyclophosphamide in mice.

Beta-lactamase as a probe of membrane protein assembly and protein export

The enzyme TEM beta-lactamase constitutes a versatile gene-fusion marker for studies on membrane proteins and protein export in bacteria. The mature form of this normally periplasmic enzyme displays readily detectable and distinctly different phenotypes when localized to the bacterial cytoplasm versus the periplasm, and thus provides a useful alternative to alkaline phosphatase for probing the topology of cytoplasmic membrane proteins. Cells producing translocated forms of beta-lactamase can be directly selected as ampicillin-resistant colonies, and consequently a beta-lactamase fusion approach can be used for positive selection for export signals, and for rapid assessment of whether any protein expressed in Escherichia coli inserts into the bacterial cytoplasmic membrane. The level of ampicillin resistance conferred on a cell by an extracytoplasmic beta-lactamase derivative depends on its level of expression, and therefore a beta-lactamase fusion approach can be used to directly select for increased yields of any periplasmic or membrane-bound gene products expressed in E. coli.

The oxidative inactivation of mitochondrial electron transport chain components and ATPase

Bovine heart submitochondrial particles (SMP) were exposed to continuous fluxes of hydroxyl radical (.OH) alone, superoxide anion radical (O2-) alone, or mixtures of .OH and O2-, by gamma radiolysis in the presence of 100% N2O (.OH exposure), 100% O2 + formate (O2- exposure), or 100% O2 alone (.OH + O2- exposure). Hydrogen peroxide effects were studied by addition of pure H2O2. NADH dehydrogenase, NADH oxidase, succinate dehydrogenase, succinate oxidase, and ATPase activities (Vmax) were rapidly inactivated by .OH (10% inactivation at 15-40 nmol of .OH/mg of SMP protein, 50-90% inactivation at 600 nmol of .OH/mg of SMP protein) and by .OH + O2- (10% inactivation at 20-80 nmol of .OH + O2-/mg of SMP protein, 45-75% inactivation at 600 nmol of .OH + O2-/mg of SMP protein). Importantly, O2- was a highly efficient inactivator of NADH dehydrogenase, NADH oxidase, and ATPase (10% inactivation at 20-50 nmol of O2-/mg of SMP protein, 40% inactivation at 600 nmol of O2-/mg of SMP protein), a mildly efficient inactivator of succinate dehydrogenase (10% inactivation at 150 nmol of O2-/mg of SMP protein, 30% inactivation at 600 nmol of O2-/mg of SMP protein), and a poor inactivator of succinate oxidase (less than 10% inactivation at 600 nmol of O2-/mg of SMP protein). H2O2 partially inactivated NADH dehydrogenase, NADH oxidase, and cytochrome oxidase, but even 10% loss of these activities required at least 500-600 nmol of H2O2/mg of SMP protein. Cytochrome oxidase activity (oxygen consumption supported by ascorbate + N,N,N',N'-tetramethyl-p-phenylenediamine) was remarkably resistant to oxidative inactivation, with less than 20% loss of activity evident even at .OH, O2-, OH + O2-, or H2O2 concentrations of 600 nmol/mg of SMP protein. Cytochrome c oxidase activity, however (oxidation of, added, ferrocytochrome c), exhibited more than a 40% inactivation at 600 nmol of .OH/mg of SMP protein. The .OH-dependent inactivations reported above were largely inhibitable by the .OH scavenger mannitol. In contrast, the O2(-)-dependent inactivations were inhibited by active superoxide dismutase, but not by denatured superoxide dismutase or catalase. Membrane lipid peroxidation was evident with .OH exposure but could be prevented by various lipid-soluble antioxidants which did not protect enzymatic activities at all.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of chronic caffeine administration on peripheral adenosine receptors

Rat platelets and adipocytes were used as models to investigate alterations of the A2- and of the A1-adenosine receptor-adenylate cyclase system of peripheral cells caused by chronic caffeine administration. The maximum effects of 5'-N-ethylcarboxamidoadenosine (NECA) to stimulate adenylate cyclase activity in suspensions of platelet membranes and to inhibit aggregation were significantly greater with platelets from caffeine-treated rats than from control rats. The effects of 1 to 100 nM prostaglandin E1 to inhibit platelet aggregation and to stimulate adenylate cyclase activity in platelet membranes were also significantly greater with caffeine-treated than with control rats. These data suggest that the increased ability of NECA to inhibit platelet aggregation after chronic caffeine ingestion was a result of increased cyclic AMP accumulation induced by this agonist. The increased stimulatory effect of NECA on adenylate cyclase in platelet membranes could be due to an increased A2-adenosine receptor number and/or an increased functional coupling between A2-adenosine receptor and stimulatory guanine nucleotide binding proteins. In contrast, although A1-receptor number was 37% higher in fat cell membranes from caffeine-treated rats than in those from control rats, increased A1-adenosine receptor-mediated inhibition of lipolysis and of adenylate cyclase was not detected. Thus, chronic caffeine consumption causes alterations in the response of some but not all peripheral cell types to agonists of adenosine receptors.

Immunomodulation of musk-moxa-string therapy in patients with scrofula

The effects of musk-moxa-string therapy on the immune system in man were investigated in 39 patients with scrofula. Before treatment, the numbers of peripheral blood (PB) CD3+ and DC4+ cells and the ratio CD4+/CD8+ were found to be lower in patients with scrofula than in normal subjects, while those of B cells and DR+ cells were higher. Response of peripheral blood mononuclear cells (PBMC) to phytohemagglutinin (PHA) diminished in patients with scrofula. At month 2-6 of musk-moxa-string therapy the number of PB CD8+ cells showed slight diminution along with significant increases in CD3+ and CD4+ cells and CD4+/CD8+ ratio in total lymphocytes (P less than 0.001). In vitro a marked increased blastogenic response to mitogen stimulation with PHA was observed in PBMC of patients with scrofula after treatment (P less than 0.001). In contrast, B lymphocytes, monocytes, DR+ cells and blastogenic response to concanavalin A and pokeweed mitogen were not influenced by musk-moxa-string therapy.

Studies on monoclonal anti-isotypic and anti-idiotypic antibodies against leukemia and myeloma: II. Preparation and characteristics of monoclonal anti-isotypic antibodies to IgM from B chronic lymphocytic leukemia

Five hybridomas producing McAbs against human serum IgM-isotype were obtained by fusing the myeloma NS-1 cell and the BALB/C murine spleen cell which had been immunized by serum IgM of patient with B chronic lymphocytic leukemia (B-CLL). These McAbs only reacted with human IgM, not with other immunoglobulins in ELISA and immune double diffusion test. An approximate positive rate of peripheral blood lymphocyte (PBL) was got when these McAbs and the McAbs against B cell were tested by indirect immunofluorescent assay. The positive rate was similar to that obtained by direct immunofluorescent test. Immunoblotting showed that the molecular weight of the antigen to these McAbs was 70-90 Kd, indicating that the antigen was IgM. The practical value of the McAbs against human IgM was also discussed.

[Studies on the changes in calcium fluxes in ts-RSV LA 90 cells transformation]

To study the role of Ca2+ fluxes and [Ca2+]i in cell transformation by the v-src gene, ts-RSV LA 90 cells was used in this experiment. Ca2+ fluxes across the plasma membrane was measured with radioisotopes. The relative [Ca2+]i in LA 90 cells loaded Indo-1AM was measured by computer-based Optical Multichannel Analyzer connected with fluorescence microscopy. It was observed that changes in rate of Ca2+ fluxes across the plasma membrane are one of the earliest detectable changes of LA 90 cells transformation. Rates of Ca2+ fluxes in transformed LA 90 cells (40 degrees C) is higher than that in normal LA 90 cells (33 degrees C) and rates of Ca2+ fluxes increased in 25 minutes when LA 90 cells shifted from nonpermissive (40 degrees C) to permissive (33 degrees C) temperature. TMB-8 inhibited increases in rate of Ca2+ efflux induced by pp 60 v-src, and increase in rate of Ca2+ efflux in normal LA 90 cells was stimulated by calf serum. The rate of Ca2+ efflux was related to the changes in temperature. The increase in rate of Ca2+ influx induced by pp 60 v-src could be blocked by verapamil. The rate of Ca2+ influx was not affected by the changes in temperature. The increase in relative [Ca2+]i induced by pp 60 v-src is one of the early events in the transformation process. The level of [Ca2+]i in transformed LA 90 cells was about 2-3 times as much as that in normal LA 90 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on monoclonal anti-isotypic and anti-idiotypic antibodies against leukemia and myeloma: I. Study on monoclonal anti-idiotypic antibodies against lambda chain protein of myeloma

We used lambda chain extracted from urine of patient with myeloma (IgD lambda) as antigen for immunizing BALB/C mice, and 86 hybridoma cell clones secreting monoclonal antibodies (McAb) were obtained after fusing twice and cloning 3-4 times. 15 of these clones secreted monoclonal anti-idiotypic antibodies (anti-Id McAb). The results showed that 12 of 15 anti-Id antibodies reacted only with homologous lambda chain and IgD, not with lambda chain, kappa chain, IgG, IgA, IgM, IgD, IgE, albumin and paraglobulin from normal subjects. Indirect immunofluorescent assay demonstrated that positive reaction rate between anti-Id McAbs and peripheral blood lymphocytes or bone marrow cells of the patient with myeloma was up to 23%. No reaction was observed between anti-Id McAb and peripheral blood lymphocytes or bone marrow cells from normal subjects. Some of these McAbs presented positive reaction with plasmacytoma cell lines cultured in our laboratory.

[Study on natural infection of epidemic haemorrhagic fever virus in Leptotrombidium scutellare]

Leptotrombidium (L.) scutellare was considered to be the suspected vector of epidemic haemorrhagic fever (EHF). In order to clarify the relationship between this mite and EHF, from Oct to Nov 1988 and Oct of 1989, the larvae of this mite were collected from rats in areas with constantly high incidence of EHF in Shanxi Province and larvae with only small quantity of meal were selected and for more than 15 days before isolation of EHFV. Six strains of virus were isolated. The viruses isolated were identified to be EHFV by serum test, immunofluorescent blocking test as well as neutralization test. The above results further demonstrate this mite can naturally be infected by EHFV and therefore serve as vector of EHF.