Induction of protein oxidation in human low density lipoprotein by the photosensitive organic hydroperoxide, N,N'-bis(2-hydroxyperoxy-2-methoxyethyl)-1,4,5,8-naphthalene-tetra-carb oxylic- diimide

We have developed a new molecular probe, N,N'-bis(2-hydroxyperoxy-2-methyoxyethyl)-1,4,5,8-naphthalen e-tetra-carboxylic- diimide (NP-III), that specifically generates hydroxyl radical upon irradiation with longer wavelength ultraviolet light (UVA). Hydroxyl radicals are generated only upon irradiation, thus NP-III is a new controllable hydroxyl radical source. Apolipoprotein (apo-B) of human low density lipoprotein (LDL), and bovine serum alubumin (BSA), were irradiated with UVA in the presence of NP-III and their oxidation was evaluated by two independent methods: assay of protein carbonyl groups and gel electrophoresis. NP-III oxidized apo-B and BSA in a time- and concentration-dependent manner. The results demonstrate that NP-III is a controllable, precise, and potentially tagetable source of hydroxyl radicals with which to induce protein oxidation.

Potentiation by calcium ions of [3H]MK-801 binding to an ion channel associated with the N-methyl-D-aspartate receptor complex in rat brain

In vitro addition of Ca2+ ions was effective in almost doubling binding of [3H](+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imi ne (MK-801) before equilibrium to an ion channel associated with an N-methyl-D-aspartate (NMDA)-sensitive subclass of brain excitatory amino acid receptors. The addition of inhibitors for phospholipase (PLase) A2 markedly reduced binding in the absence of added Ca2+ ions, while Ca2+ ions restored the reduction to the level found in the absence of the inhibitors. Pretreatment with PLases A2 and C but not D was effective in potentiating [3H]MK-801 binding in a biphasic manner at a concentration range of 5 mU/ml-10 U/ml. Moreover, PLases A2 and C at low concentrations not only suppressed the abilities of 3 different agonists to potentiate [3H]MK-801 binding before equilibrium, but also reduced that of Ca2+ ions. These results suggest that Ca2+ ions may potentiate [3H]MK-801 binding to the NMDA channel highly permeable to Ca2+ ions through a mechanism common to that underlying potentiation by exogenous PLase A2 and/or C.

[Early diagnosis of acoustic neuroma]

The diagnostic findings in 31 patients (32 ears) with acoustic neuromas are reported. In patients suspicious of acoustic neuroma, case history and clinical examination are important. In our material of 31 patients with acoustic neuromas, hearing loss was presented in 94% (slow onset 87%, sudden onset 10% and fluctuating 3%), tinnitus in 91%, vestibular symptoms (dizziness or vertigo) in 62%. It should be stressed that in patients with unilateral hearing loss (or tinnitus) or vestibular symptoms, it is necessary to exclude the presence of an acoustic neuroma. In addition, the trigeminal never was affected in 34%, which was encountered in tumours larger than 26-40 mm. There was a positive correlation between duration of symptoms and size of the tumour, but there was no correlation between hearing loss and size of the tumour. Brainstem response audiometry (ABR) exhibited a very high sensitivity (100%), making it a suitable single test for screening patients suspected to have an acoustic neuroma.

Analysis of reduced and oxidized lipoic acid in biological samples by high-performance liquid chromatography

Using HPLC with electrochemical detection at a dual Hg/Au electrode, both reduced and oxidized lipoic acid can be measured in biological samples after addition of lipoic acid. The method does not detect bound lipoic acid, which must be liberated by strong acid or base hydrolysis. The detection limit for this HPLC method is 0.01 nmol of dihydrolipoate and 0.05 nmol of lipoate. Baseline separation of lipoate and dihydrolipoate is achieved on a 10 cm octadecyl column. The analysis is rapid (8 min/sample) and uses a single HPLC pump with isocratic mobile phase. The method has been adapted to study cellular and whole animal reduction of lipoate, membrane transport of lipoate and dihydrolipoate, and subcellular enzymes that reduce lipoate.

Preferential induction by stress of the N-methyl-D-aspartate recognition domain in discrete structures of rat brain

Immobilization stress in water for 3 h was effective in inducing significant potentiation of [3H](+)-5-methyl-10,11-dihydro-5H- dibenzo [a,d] cyclohepten-5,10-imine ([3H]MK-801) binding 5 days after the stressful manipulation in rat hypothalamus and cerebellum when determined before equilibrium in the absence of any added agonists, in addition to resulting in marked reduction of rearing behaviors of animals. However, the stressful manipulation failed to modulate the [3H]MK-801 binding in other central regions examined, and binding of either [3H]DL-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid or [3H]kainic acid was not significantly affected in all brain structures studied 5 days after the stress application. In contrast, the stressful procedures potentiated binding of both L-[3H]glutamic ([3H]Glu) and [3H]DL-(E)-2-amino-4-propyl-5-phosphono-3-pentenoic ([3H]CGP-39653) acids in the hypothalamus and cerebellum 5 days later, without affecting binding of [3H]-glycine and 5,7-dichloro[3H]kynurenic acid. The systemic administration of corticosterone mimicked the stress manipulation at doses of 5-50 mg/kg in terms of inducing significant enhancement of binding of both [3H]Glu and [3H]CGP-39653 in the hypothalamus and cerebellum when determined 5 days after the single administration. The translation inhibitor cycloheximide was effective in preventing the stress-induced potentiation of [3H]Glu binding in the cerebellum, without altering that in the hypothalamus. Furthermore, the stressful handling significantly increased the densities of [3H]Glu binding sites in the hypothalamus and cerebellum, with the affinities being unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Reassessment of digoxin and other low-dose positive inotropes in the treatment of chronic heart failure

Digoxin and other low doses of drugs that have inotropic properties may have an important role to play in the therapy of patients with chronic heart failure. There is convincing evidence that digoxin is effective in relieving the signs and symptoms of heart failure due to systolic dysfunction. While earlier results with some of the other agents have been disappointing, recent data suggest that a reevaluation of these agents is necessary. There is now compelling evidence that lower doses of these agents may be clinically useful without necessarily having any significant hemodynamic effects. The recent experience with vesnarinone is especially promising in showing that therapy with these agents may improve survival in addition to improving clinical status. It is becoming recognized that hemodynamic activity should not necessarily be a prerequisite for clinical utility for those agents. The neuroendocrine and electrophysiologic effects of many of these agents, including digitalis, remain incompletely characterized and may play an important role in their therapeutic benefit. It appears that certain drugs that have inotropic properties may be effective only when their inotropic effects are not readily demonstrated. Further research into the appropriate mechanisms of action and proper dosing of these drugs may lead to a renewed interest in the use of positive inotropes for chronic heart failure.

Recovery of antioxidants and reduction in lipid hydroperoxides in murine epidermis and dermis after acute ultraviolet radiation exposure

In previous studies we have found that a single acute dose of ultraviolet radiation to murine skin causes a large degree of destruction of enzymic and non-enzymic antioxidants immediately after irradiation. In the present study, we wished to elucidate the recovery of antioxidants after a single dose of ultraviolet (UV) radiation. We measured antioxidants and lipid hydroperoxides (as a marker of membrane damage) in murine epidermis and the dermis at 0, 3, 12, 24, 72 and 120 h after exposure to UV radiation (25 J/cm2, UVA+UVB). Lipid hydroperoxides showed the highest values immediately after UV exposure and returned to control values within 24 h in both epidermis and dermis. The activities of catalase, glutathione peroxidase and glutathione reductase showed the lowest activities immediately after UV exposure; superoxide dismutase activities reached a minimum at 3 h postexposure. The pattern of recovery was different for each enzyme and for epidermis and dermis. The activities of superoxide dismutase and catalase decreased remarkably and recovered slowly. Superoxide dismutase in the dermis recovered full activity by 120 h and in the epidermis by 12 h. Catalase activity in both epidermis and dermis had returned to only 50% of control activity at 120 h, although the epidermis showed a temporary increase (to 93%) at 24 h. Glutathione peroxidase and glutathione reductase were slightly decreased immediately after irradiation, recovered to 100% at 3 h and then increased to 200-250% in both the epidermis and the dermis at various times; values had returned to 100% in epidermis by 120 h but remained elevated in dermis.(ABSTRACT TRUNCATED AT 250 WORDS)

IL-2 production by myofibroblasts from post-radiation fibrosis in breast cancer patients

The origin of cell activation in post-radiation fibrosis and its chronic extension are still poorly understood. Since local IL-2 cancer treatment sometimes triggers intraperitoneal fibrosis we have analyzed three myofibroblastic cell strains from post-radiation skin fibrosis (FPR7, FPR10 and FPR15) for their interactions with IL-2. In these cells we have observed the surface expression of the two chains of the IL-2R (IL-2R alpha beta), the presence of the 0.9 kb transcript specific for the IL-2 gene and, by flow cytometry with anti-IL-2 mAbs, the presence of IL-2 immunoreactive material inside the cells up to 8 days after subculture. The FPR cell lines secreted IL-2, as determined by ELISA. The secreted IL-2 is biologically active since it sustains the proliferation of the IL-2-dependent murine lymphoid cell line CTLL2 and preincubation with anti-IL-2 blocking mAbs completely abolishes this activity. Overnight incubation of FPR cells with polyclonal anti-IL-2 antibodies leads to a decreased expression of the membrane adhesion molecules ICAM-1 and CD44, suggesting the existence of an autocrine/paracrine loop involved in the surface expression of these antigens. By contrast, in normal adult skin fibroblasts we did not detect IL-2 gene activation. In vivo, IL-2 secretion by post-radiation fibrosis fibroblasts and the subsequent up-regulation of ICAM-1 and CD44 may represent key events during the process that leads to radiation fibrosis.

How interleukin-2 can affect human fibroblasts behaviour

The alpha and beta chains of the Interleukin 2 receptor (IL2R alpha and IL2R beta) were detected at the surface of cultured fibroblastic cells by flow cytometry, using monoclonal antibodies (mAbs) directed against the IL2R alpha and the IL2R beta. These cells bound FITC-IL2 and this binding was inhibited by an excess of cold ligand and by mAbs recognizing the IL2 binding sites of the alpha and beta chains. Internalisation studies show that the fibroblastic IL2R/IL2 complex is internalized at 37 degrees C. By Northern Blot analysis we detected the presence of specific transcripts for the IL2R alpha and IL2R beta genes. Finally, the addition of exogenous IL2 specifically modified the surface expression of different antigens involved in the process of immunosurveillance. Indeed, IL2, at concentrations affecting the high affinity IL2R, caused the down regulation of ICAM-1 protein. IL2 also decreased the surface expression of the class I and class II HLA. By contrast, the use of IL2 concentrations which saturate the intermediate affinity IL2R beta caused the up regulation of the surface expression of the ICAM-1 protein. ICAM-1 is the natural ligand for the LFA-1 integrin expressed at the surface of lymphoid cells. ICAM-1/LFA-1 interactions favour homotypic and heterotypic cell-cell adhesion. Since human fibroblasts express an LFA-1 like molecule, we propose that in these cells IL2 can modify homotypic and heterotypic interactions acting on the surface expression of ICAM-1 protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha-lipoic acid reduction by mammalian cells to the dithiol form, and release into the culture medium

Lipoic acid has been reported recently to be an effective antioxidant in biological systems. It may act in vivo through reduction to its dithiol form, dihydrolipoic acid. Using a dual Hg/Au electrode, and HPLC with electrochemical detection, a method was developed which allowed simultaneous measurement of lipoic acid and dihydrolipoic acid, at nanomolar levels. (RS)-alpha-Lipoic acid was added to human cells in tissue culture (Jurkat T-lymphocytes and primary neonatal diploid fibroblasts). Lipoic acid was converted rapidly by the cells to dihydrolipoic acid, which accumulated in the cell pellet. Monitored over a 2-hr interval, dihydrolipoic acid was released, and several-fold more dihydrolipoic acid could be found in the medium than in the pellet.

Dose-response effects of acute ultraviolet irradiation on antioxidants and molecular markers of oxidation in murine epidermis and dermis

There has not as yet been an integrated, comprehensive study of the responses of dermis and epidermis in vivo to a wide range of ultraviolet (UV) doses, encompassing all major antioxidants and a sensitive marker of oxidative damage. We have irradiated hairless mice with simulated solar light at doses of 2, 5, 12.5, and 25 J/cm2 combined UVA and UVB (0.8 to 10 MED) and measured enzymic and non-enzymic antioxidants as well as lipid hydroperoxides in both epidermis and dermis to elucidate the response of cutaneous antioxidant defense mechanisms to UV stress. Among the nonenzymic antioxidants two different dose-response patterns were seen. Ascorbate was rapidly depleted at doses between 0 and 5 J/cm2 but was less affected between 5 and 25 J/cm2. In contrast, glutathione, ubiquinol/one, and alpha-tocopherol levels remained approximately equal to control levels between 0 and 5 J/cm2, then decreased to varying degrees from 5 to 25 J/cm2; ubiquinol was almost completely depleted, whereas alpha-tocopherol dropped only 30%. The concentration of lipid hydroperoxides increased throughout the dose range. These results may be explained partly by direct destruction of some antioxidants by UV light, partly by the separate antioxidant functions of the compounds, and partly by recycling of some antioxidants (e.g., alpha-tocopherol) at the expense of others (e.g., ubiquinol). Even at the lowest dose (0.8 MED) lipid hydroperoxide formation was observed. Among the enzymic antioxidants, superoxide dismutase activity decreased significantly (to 63.6% of initial activity for epidermis and 51.5% for dermis at 25 J), whereas activities of glutathione peroxidase and glutathione reductase decreased slightly. Catalase activity decreased dramatically at doses above 5 J (to 11.8% of initial activity in epidermis and 27.7% in dermis at 25 J). The dramatic loss of catalase is almost entirely accounted for by direct destruction by the simulated solar light, but superoxide dismutase was unaffected by direct exposure; hence its destruction must be due to indirect effects, either mediated by free radicals or other harmful species formed upon irradiation. At low doses of UV light many components of the cutaneous antioxidant system were damaged, whereas at high doses all components were damaged and some were almost completely destroyed.

Discrimination by added ions of ligands at ionotropic excitatory amino acid receptors insensitive to N-methyl-D-aspartate in rat brain using membrane binding techniques

The addition of potassium thiocyanate almost quadrupled binding of [3H]DL-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) to an AMPA-sensitive subclass of brain excitatory amino acid receptors in rat brain synaptic membranes, treated with Triton X-100. Among several ligands tested, quisqualic acid (QA) was the most potent displacer of [3H]AMPA binding in the absence of added SCN- ions, followed by AMPA, 6,7-dinitroquinoxaline-2,3-dione (DNQX), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), glutamic (Glu) and kainic (KA) acids in a rank order of decreasing potency. The addition of SCN- ions was effective in significantly reducing the potencies of antagonists such as DNQX and CNQX, without affecting those of agonists including QA, AMPA, Glu and KA. On the other, the addition of Ca2+ ions significantly inhibited [3H]KA binding in a concentration-dependent manner at concentrations of above 2.5 mM. Calcium ions were also effective in significantly potentiating potencies to displace [3H]KA binding of antagonists such as DNQX and CNQX, with concomitant reduction of those of agonists including KA, QA and Glu. However, N-methyl-D-aspartic acid (NMDA) did not affect binding of both radioligands at concentrations of below 0.1 mM. These results suggest that both SCN- and Ca2+ ions may be useful to discriminate agonists and antagonists among a variety of displacers of ligand binding to the non-NMDA receptors in the brain.

Binding of [3H]triamcinolone acetonide to glucocorticoid receptors in brain cytosol fractions of rats with intact adrenals

Binding of [3H]triamcinolone acetonide (TA) increased with prolongation of incubation periods of up to 5 h after the onset of incubation at 2 degrees C, with a plateau thereafter persisting for at least up to 48 h in brain cytosol fractions of rats with intact adrenals. Elevation of incubation temperature to 30 degrees C resulted in a marked reduction of the binding at equilibrium which persisted for only 1 to 2 h with complete abolition thereafter. The addition of sodium molybdate was effective in doubling the maximal value at 30 degrees C without markedly affecting the binding at 2 degrees C. [3H]TA binding at equilibrium determined at 2 degrees C was a reversible, saturable and structure selective process with uneven distribution profiles in rat brain. Among a variety of steroid hormones tested, TA was the most potent displacer with progressively less potent displacement by dexamethasone, deoxycorticosterone, progesterone, prednisolone, hydrocortisone and corticosterone. Among discrete brain regions examined, the highest density was detected in the cerebellum followed by the hippocampus, cerebral cortex, midbrain, striatum, hypothalamus and medulla-pons in a rank order of decreasing density. In contrast, both the cerebellum and medulla-pons had significantly higher affinities for [3H]TA than the cerebral cortex. Moreover, the binding was markedly inhibited by Zn2+ ions at 10 microM due to a decrease in the affinity. These results suggest that [3H]TA labels a ligand recognition domain on the cytoplastic glucocorticoid receptor complex with different affinities in rat brain.

Characterization of effector cells against B16 melanoma in mice inoculated with allogeneic spleen cells

Inbred C57BL/6 (B6) mice which had received an inoculation of allogeneic spleen cells showed remarkable antitumor activity against syngeneic tumor challenge with B16 melanoma cells 3 days after the allogeneic cell inoculation. This antitumor activity was not specific to the inoculated alloantigen, since the challenging B16 cells are syngeneic to B6 mice and since it was induced by BALB/c spleen cells as well as C3H/He spleen cells. The antitumor activity was sensitive to an in vivo treatment with anti-asialo GM1 (AGM1) antiserum or anti-Thy.1 monoclonal antibody (mAb) just before the tumor challenge and was resistant to an in vivo treatment with anti-CD8 (Ly.2) mAb. These results suggest that AGM1+Thy.1+CD8- activated natural killer (NK) cells were generated by alloantigen inoculation and took an important part in the antitumor effect of the alloantigen inoculation.

Enzymic and non-enzymic antioxidants in epidermis and dermis of human skin

We measured enzymic and non-enzymic antioxidants in human epidermis and dermis from six healthy volunteers undergoing surgical procedures. Epidermis was separated from dermis by curettage and antioxidants were measured by high-performance liquid chromatography (HPLC) or standard spectrophotometric methods. The concentration of every antioxidant (referenced to skin wet weight) was higher in the epidermis than in the dermis. Among the enzymic antioxidants, the activities of superoxide dismutase, glutathione peroxidase, and glutathione reductase were higher in the epidermis compared to the dermis by 126, 61 and 215%, respectively. Catalase activity in particular was much higher (720%) in the epidermis. Glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase, which provide reduced nicotinamide adenine dinucleotide phosphate (NADPH), also showed higher activity in the epidermis than the dermis by 111% and 313%, respectively. Among the lipophilic antioxidants, the concentration of alpha-tocopherol was higher in the epidermis than the dermis by 90%. The concentration of ubiquinol 10 was especially higher in the epidermis, by 900%. Among the hydrophilic antioxidants, concentrations of ascorbic acid and uric acid were also higher in the epidermis than in the dermis by 425 and 488%, respectively. Reduced glutathione and total glutathione were higher in the epidermis than in the dermis by 513 and 471%. Thus the antioxidant capacity of the human epidermis is far greater than that of dermis. As the epidermis composes the outermost 10% of the skin and acts as the initial barrier to oxidant assault, it is perhaps not surprising that it has higher levels of antioxidants.

Novel preservation solution permits 24-hour preservation in rat and baboon cardiac transplant models

BACKGROUND

Cardiac preservation for transplantation disrupts normal vascular homeostatic mechanisms. Hypoxia and reoxygenation increase endothelial cell permeability, induce procoagulant activity, and alter endothelial cell/leukocyte interactions, with a parallel reduction in endothelial cAMP and nitric oxide levels. Because hypoxia/reoxygenation simulates a significant component of the global ischemia/reperfusion of cardiac transplantation, we hypothesized that preservation failure may be related to these perturbations. This work focuses on repleting the intercellular/intracellular second messengers nitric oxide/cGMP and cAMP in the donor heart to enhance cardiac preservation for transplantation.

METHODS AND RESULTS

A heterotopic rat heart transplant model was used to compare lactated Ringer's (LR) and University of Wisconsin (UW) solutions to a novel storage solution (Columbia University solution, CU), which contains a cAMP analogue (dibutyryl cAMP) and nitroglycerin (to enhance nitric oxide-related mechanisms). By 24 to 28 hours of preservation, no LR hearts survived (n = 9), 35% of UW hearts survived (n = 20), and 88% of CU-preserved hearts survived (n = 8; P < .05) versus LR or UW). The viability of preserved hearts was explored by determining whether CU preservation enabled myocytes to maintain resting membrane potentials and preserve their ability to generate an action potential in response to a field stimulus. Of 24 sites explored with a microelectrode in UW-preserved hearts, only 4% were able to generate an action potential, compared with 75% of 36 sites in CU-preserved hearts (P < .001), with corresponding preservation of resting membrane potential in the CU-preserved hearts (-13 mV for UW versus -54 mV for CU, P < .001). Orthotopic baboon cardiac transplantation performed after 24-hour simple hypothermic preservation demonstrated that no UW-preserved heart (n = 4) survived the perioperative period; in contrast, four of five hearts stored for 24 hours in CU solution sustained the recipient with minimal inotropic support, and two animals survived long-term.

CONCLUSIONS

Sustaining higher levels of intercellular/intracellular second messengers cAMP and nitric oxide/cGMP provides a new approach to enhancing cardiac preservation.

Further evidence for multiple forms of an N-methyl-D-aspartate recognition domain in rat brain using membrane binding techniques

Pretreatment with sulfhydryl-reactive agents, such as N-ethylmaleimide and p-chloromercuriphenylsulfonic acid, invariably resulted in marked inhibition of the binding of DL-(E)-2-amino-4-[3H]propyl-5-phosphono-3-pentenoic acid ([3H]CGP 39653), a competitive antagonist at an N-methyl-D-aspartate (NMDA)-sensitive subclass of central excitatory amino acid receptors, in brain synaptic membranes extensively washed and treated with Triton X-100, but did not significantly affect the binding of L-[3H]-glutamic acid ([3H]Glu), an endogenous agonist. The pretreatment was effective in reducing the binding of [3H]-CGP 39653 at equilibrium, without altering the initial association rate, and decreased the affinity for the ligand. Pretreatment with sulfhydryl-reactive agents also enhanced the potencies of NMDA agonists to displace [3H]-CGP 39653 binding and attenuated those of NMDA antagonists, but had little effect on the potencies of the agonists and antagonists to displace [3H]Glu binding. The binding of both [3H]CGP 39653 and [3H]Glu was similarly sensitive to pretreatment with four different proteases in Triton-treated membranes, whereas pretreatment with phospholipase A2 or C markedly inhibited [3H]CGP 39653 binding without altering [3H]Glu binding. Moreover, both phospholipases not only induced enhancement of the abilities of NMDA agonists to displace the binding of [3H]CGP 39653 and [3H]Glu, but also caused diminution of those of NMDA antagonists. These results suggest that both sulfhydryl-reactive agents and phospholipases may predominantly interfere with radiolabeling of the NMDA recognition domain in a state favorable to an antagonist by [3H]CGP 39653, with concomitant facilitation of that in an antagonist-preferring form by [3H]Glu. The possible presence of multiple forms of the NMDA recognition domain is further supported by these data.

[Higher production of tumor necrosis factor (TNF) elicited by a biological response modifier (BRM) in aging mice]

We investigated age-related changes in the capacity for tumor necrosis factor (TNF) production in young and aged inbred C3H/He mice by injecting them with OK-432, a biological response modifier (BRM). An intravenous injection of 0.4mg of OK-432 was found to induce TNF production and two consecutive injections of 2KE of OK-432 induced much higher TNF production. Both the single and two consecutive injections of OK-432 induced significantly higher TNF production in aged mice than in young ones. Furthermore, the TNF-productive response to the two consecutive injections of OK-432 seemed to increase with aging. Male mice tended to show a marginally higher TNF-productive response than females. The mechanism by which aged mice have a higher capacity for TNF production is not clear. The following possibilities are conceivable. 1) Macrophages which are major TNF producer cells may be activated in aged mice. 2) Specific T cells which are cross-reactive to antigenic determinants in OK-432 may be increased in number in aging mice and activate macrophages effectively to produce TNF when stimulated by OK-432. In general, immunological functions tend to decline with aging. Our present results, however, suggest that by using an appropriate BRM we may be able to induce higher TNF production in the aged. This might lead to effective prevention and therapy for tumors, which increase in incidence with age.

Vitamin E recycling in human erythrocyte membranes

Vitamin E, the major lipid chain-breaking antioxidant in erythrocyte membranes, is present in low concentration, suggesting that mechanisms should exist to protect against its loss. Enzymatic pathways for the recycling of vitamin E from its tocopheroxyl radical have been observed previously in inner membranes of mitochondria and microsomes. These pathways use electron transport enzymes and their substrates to regenerate vitamin E. Erythrocyte membranes also contain significant NADH-cytochrome c reductase activity, as well as cytochrome b5, the function of which is not yet known. Using an enzymatic oxidation system composed of lipoxygenase and arachidonic acid, free radicals were produced in human erythrocyte membranes, and their reaction with chromanols was followed by ESR and high performance liquid chromatography (HPLC). Since the endogenous vitamin E content of the membranes is very low, we used a vitamin E homologue lacking the hydrocarbon chain (2,2,5,7,8-pentamethyl-6-hydroxychromane) as a probe molecule for ESR measurements. However, parallel HPLC determinations of lipid hydroperoxides and of endogenous vitamin E confirmed the results obtained by ESR. It was found that protection against the loss of vitamin E can be provided either by NADH-cytochrome b5-dependent enzymatic recycling or by a nonenzymatic pathway involving ascorbate and dihydrolipoic acid.

Comparative studies on binding of 3 different ligands to the N-methyl-D-aspartate recognition domain in brain synaptic membranes treated with Triton X-100

Treatment with a low concentration of Triton X-100 almost tripled the binding of [3H]D,L-(E)-2-amino-4-propyl-5-phosphono-3-pentenoic acid (CGP 39653), a novel competitive antagonist at an N-methyl-D-aspartate (NMDA)-sensitive subclass of brain excitatory amino acid receptors, in synaptic membranes of the rat brain. The binding linearly increased with increasing protein concentrations of up to 0.4 mg/ml and also increased in proportion to incubation time with a plateau within 60 min after the initiation of incubation at 2 degrees C in Triton-treated membranes. Elevation of incubation temperature from 2 degrees C to 30 degrees C resulted in a marked decrease in the binding at equilibrium by 80%, and a maximal level was obtained within 1 min after the initiation of incubation at 30 degrees C with a gradual decline of up to 10 min. Bound [3H]CGP 39653 was rapidly dissociated by the addition of excess unlabeled L-glutamic acid (Glu), and the time required to attain complete dissociation was 60 min at 2 degrees C and 1 min at 30 degrees C, respectively. Among several agonists and antagonists tested, Glu was the most potent displacer of [3H]CGP 39653 binding with progressively less potent displacement by D-2-amino-5-phosphonovaleric, (+-)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic (CPP), D-2-amino-7-phosphonoheptanoic, N-methyl-D-aspartic and N-methyl-L-aspartic acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Spectroscopic and kinetic studies of lipases solubilized in reverse micelles

The conformation and activity of three different lipases have been studied in reverse micelles formed by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in isooctane. In the case of human pancreatic lipase, the conformation of the polypeptide chain--as judged from far-UV circular dichroism measurements--is only slightly altered after the enzyme is transferred from a bulk aqueous solution into the microenvironment of reverse micelles. Significant spectral changes in the near-UV circular dichroism and fluorescence spectrum indicate, however, that the solvation of aromatic amino acid side chains is considerably different in reverse micelles. Conversely, the circular dichroism spectra of the lipases from Candida rugosa and Pseudomonas sp. are considerably different in reverse micelles, compared with the spectra in aqueous solution, indicating that both enzymes loose the native structure at the water/AOT/oil interface. Bound substrate and/or product can prevent this denaturation. While Pseudomonas sp. and human pancreatic lipase are inhibited by tetrahydrolipstatin (THL), the lipase from Candida rugosa is not. These data, together with additional activity and inhibition data, indicate that the micellar microenvironment accentuates the difference between the different enzymes in terms of the relation structure/activity.

Differential potentiation by spermidine of abilities of a variety of displacers for [3H]MK-801 binding in hippocampal synaptic membranes

Binding of [3H](+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imi ne (MK-801) to an ion channel associated with the N-methyl-D-aspartate (NMDA)-sensitive subtype of brain excitatory amino acid receptors was studied in Triton-treated preparations of synaptic membranes of rat brain. The initial association rate of the binding measured at 30 min after onset of incubation was markedly potentiated by the addition of either L-glutamic acid (Glu) alone or both Glu and glycine (Gly) in a concentration-dependent manner at 10 nM to 0.1 mM. Potentiation occurred to a significantly greater extent in the hippocampus and cerebral cortex than in the cerebellum. In the presence of both Glu and Gly, the endogenous polyamine spermidine (SPD) further potentiated binding in hippocampal and cortical membranes at concentrations above 10 microM without significantly affecting that in cerebellar membranes. The binding of [3H]MK-801 was slowly equilibrated in 16 h. When examined in hippocampal synaptic membranes, the binding at equilibrium was markedly displaced by numerous noncompetitive antagonists for the NMDA receptor. The addition of SPD markedly enhanced potencies of those displacers having a high affinity to [3H]MK-801 binding sites, without affecting other displacers having a low affinity. These results suggest that SPD promotes transition of sites responsible for mediating NMDA responses within the channel to a state with higher affinity for noncompetitive blockers.

Support for radiolabeling of a glycine recognition domain on the N-methyl-D-aspartate receptor ionophore complex by 5,7-[3H]dichlorokynurenate in rat brain

Pretreatment with Triton X-100 more than doubled the binding of radiolabeled 5,7-dichlorokynurenic acid (DCKA), a proposed antagonist at a glycine (Gly) recognition domain on the N-methyl-D-aspartate (NMDA) receptor ionophore complex, in rat brain synaptic membranes. The binding exhibited an inverse temperature dependency, reversibility, and saturability, the binding sites consisting of a single component with a high affinity (27.5 nM) and a relatively low density (2.87 pmol/mg of protein). The binding of both [3H]DCKA and [3H]Gly was similarly displaced by numerous putative agonists and antagonists at the Gly domain in a concentration-dependent manner at a concentration range of 100 nM to 0.1 mM. Among the 24 putative ligands tested, DCKA was the second most potent displacer of the binding of both radioligands with no intrinsic affinity for the binding of [3H]kainic acid and alpha-amino-3-hydroxy-5- [3H]methylisoxazole-4-propionic acid (AMPA) to the non-NMDA receptors. In contrast, the other proposed potent Gly antagonist, 5,7-dinitroquinoxaline-2,3-dione, was active in displacing the binding of [3H]glutamic ([3H]Glu) and D,L-(E)-2-amino-4-[3H]propyl-5-phosphono-3-pentenoic acids to the NMDA recognition domain with a relatively high affinity for the non-NMDA receptors. In addition, the proposed antagonist at the AMPA-sensitive receptor, 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline, not only displaced weakly the binding of both [3H]-Gly and [3H]DCKA, but also inhibited the binding of (+)-5-[3H]methyl-10,11- dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine ([3H]MK-801) to an ion channel associated with the NMDA-sensitive receptor in the presence of added Glu alone in a manner sensitive to antagonism by further added Gly. Clear correlations were seen between potencies of the displacers to displace [3H]DCKA binding and [3H]Gly binding, in addition to between the potencies to displace [3H]-DCKA or [3H]Gly binding and to potentiate or inhibit [3H]MK-801 binding. All quinoxalines tested were invariably more potent displacers of [3H]DCKA binding than [3H]Gly binding, whereas kynurenines were similarly effective in displacing the binding of both [3H]Gly and [3H]DCKA. These results undoubtedly give support to the proposal that [3H]DCKA is one useful radioligand available in terms of its high selectivity and affinity for the Gly domain in the brain. Possible multiplicity of the Gly domain is suggested by the differential pharmacological profiles between the binding of [3H]Gly and [3H]DCKA.

Differential modulation by divalent cations of [3H]MK-801 binding in brain synaptic membranes

Endogenous divalent cations, such as Mg2+, Ca2+, and Zn2+, differentially affected the binding of (+)-[3H]5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imi ne maleate ([3H]MK-801) to an ion channel associated with an N-methyl-D-aspartate-sensitive subclass of excitatory amino acid receptors in different preparations of brain synaptic membranes. Both Mg2+ and Ca2+ were weak inhibitors of the binding in membranes which had not been extensively washed (nonwashed membranes), over a concentration range effective in markedly potentiating the binding in the absence of any added stimulants in membranes which had been extensively washed, but not treated with a detergent (untreated membranes). In membranes extensively washed and treated with Triton X-100 (Triton-treated membranes), both cations significantly potentiated the binding in the presence of added glutamate alone. In contrast, Zn2+ was invariably active as a potent inhibitor of the binding irrespective of the membrane preparations used. In untreated membranes, Ca2+ markedly accelerated the initial association rate of [3H]MK-801 binding without affecting the binding at equilibrium in a manner similar to that found with glycine, as well as with glutamate; Mg2+, however, facilitated the initial association rate with a concomitant reduction of the binding at equilibrium. Zn2+ was effective in accelerating the initial rapid phase of association, with the initial slow phase being delayed, and in markedly reducing the binding at equilibrium. Both Mg2+ and Ca2+ also facilitated dissociation of the bound [3H]MK-801 and Zn2+ slowed the dissociation in untreated membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of shear rates on protein adsorption in the total artificial heart

Plasma protein adsorption is the first event in blood-material interaction and influences subsequent platelet adhesion and thrombus formation. Thromboembolic events are strongly influenced by surface characteristics of materials and fluid dynamics inside the blood pump. In vitro flow visualization, and an animal experiment with a moving actuator total artificial heart (TAH), were performed to investigate fluid dynamic effects on protein adsorption. The different levels of shear rate inside the ventricle were determined by considering the direction of opening of the four heart valves in the implanted TAH, and the visualized flow patterns as well. Each ventricle of the explanted TAH was cut into 12 segments according to the shear rate level. The adsorbed protein on each segment was quantified using an ELISA method after soaking in 2% (w/v) SDS/PBS for 2 days. Adsorbed protein layer thicknesses were measured by the immunogold method under transmission electron microscopy. Scanning electron microscopic observation showed that the right ventricle, immobilized with albumin, displayed different degrees of platelet adhesion on each segment, whereas the left ventricle, coated with polythyleneoxide-sulfonate, indicated nearly the same platelet adhesion behavior, regardless of shear rates. The surface concentrations of adsorbed proteins in the low shear rate region are higher than those in the high shear region, which was confirmed statistically.

Albumin immobilized polyurethane and its blood compatibility

Surface pretreatment with albumin on a blood contacting material inhibits platelet adhesion, activation, and subsequent thrombus formation. Although adsorbed albumin improves blood compatibility, rapid desorption occurs when this surface is exposed to circulating blood. In this study, human serum albumin was immobilized on a polyurethane (PU) surface to investigate its blood compatibility and extended effects on a blood-material interface. The PU surface was treated with hexamethylene diisocyanate (HMDI), and the PU-HMDI was further grafted with albumin to produce an albumin immobilized PU surface (PU-albumin). The PU-albumin surface was characterized by attenuated total reflection infrared electron spectroscopy for chemical analysis, scanning electron microscopy, and dynamic contact angle. Blood compatibility was evaluated by in vitro protein adsorption, platelet adhesion, and occlusion time in an ex vivo rabbit arterio-arterial shunt. Immobilization of albumin was confirmed by the disappearance of the -NCO peak observed at 2,250 cm-1 on the PU-HMDI surface by infrared spectroscopy and the existence of sulfur atomic percent by electron spectroscopy for chemical analysis. The concentration of PU-albumin was approximately 5.8 micrograms/cm2. The PU-albumin also showed a slight increase in hydrophilicity on the Wilhelmy plate method, and there was less fibrinogen adsorption than a PU control. In addition, PU-albumin had less platelet adhesion, platelet activation, and thrombogenicity. The ex vivo occlusion time of untreated PU was 50 min, that of PU-albumin was extended to 150 min, indicating that a PU-albumin surface has better blood compatibility than PU alone.

[Mechanisms of protective action of radix Salviae miltiorrhizae (RSM) against experimental hepatic injury in rats]

The results indicated that RSM could significantly inhibit the lipid peroxidation of normal livers and cultured hepatocytes of rats, induce liver microsomal cytochrome P450 in normal rats, increase nucleic acids, proteins, urea and cerolloplasmin of damaged cultured hepatocytes of rats, relieve ultrastructural damage of cultured hepatocytes induced by CCl4. The pharmacological actions mentioned above should be considered as important mechanisms of RSM against liver injury.

[Intrauterine adhesion and ovulatory disorder following induced abortion]

Follicular stimulating hormone, luteinizing hormone, prolactin, estradiol and progesterone were measured by radioimmunoassay in 34 patients with those from 34 normal cycling women after induced abortion. The result showed that the anovulatory incidence of the patients (20.6%) was significantly higher than that of the controls (2.8%) (P less than 0.05). Increased prolactin and premature ovarian failure might be responsible for the anovulatory disorder, resulting in unsatisfactory restoration of fertility. It is suggested that the low success rate in treating patients with intrauterine adhesion after induced abortion may be due to premature ovarian failure and hyperprolactinaemia.

Simplified pressure method for respirator fit testing

A simplified pressure method has been developed for fit testing air-purifying respirators. In this method, the air-purifying cartridges are replaced by a pressure-sensing attachment and a valve. While wearers hold their breath, a small pump extracts air from the respirator cavity until a steady-state pressure is reached in 1 to 2 sec. The flow rate through the face seal leak is a unique function of this pressure, which is determined once for all respirators, regardless of the respirator's cavity volume or deformation because of pliability. The contaminant concentration inside the respirator depends on the degree of dilution by the flow through the cartridges. The cartridge flow varies among different brands and is measured once for each brand. The ratio of cartridge to leakflow is a measure of fit. This flow ratio has been measured on human subjects and has been compared to fit factors determined on the same subjects by means of photometric and particle count tests. The aerosol tests gave higher values of fit.

Respirator fit and protection through determination of air and particle leakage

A laboratory technique for determining the respirator protection factor from a test of fit is described. A dynamic pressure test quantifies the air flow through the leak. Calibration data, stored in a computer, relate the contaminant influx to this air flow, and a similar pressure test determines the flow through the respirator cartridges and, therefore, the dilution characteristics. Contaminant removal characteristics of the cartridges are stored in the computer. The contaminant penetration is calculated from these data on flow and removal efficiency. Through specification of the aerosol size distribution and the method of measurement, protection factors are calculated for specific work environments, work loads and respirator cartridges. The protection factor is shown to be highly dependent on the method of measuring the contaminant and on the cartridges used.

Free radical recycling and intramembrane mobility in the antioxidant properties of alpha-tocopherol and alpha-tocotrienol

d-Alpha-tocopherol (2R,4'R,8'R-Alpha-tocopherol) and d-alpha-tocotrienol are two vitamin E constituents having the same aromatic chromanol "head" but differing in their hydrocarbon "tail": tocopherol with a saturated and toctrienol with an unsaturated isoprenoid chain. d-Alpha-tocopherol has the highest vitamin E activity, while d-alpha-tocotrienol manifests only about 30% of this activity. Since vitamin E is considered to be physiologically the most important lipid-soluble chain-breaking antioxidant of membranes, we studied alpha-tocotrienol as compared to alpha-tocopherol under conditions which are important for their antioxidant function. d-Alpha-tocotrienol possesses 40-60 times higher antioxidant activity against (Fe2+ + ascorbate)- and (Fe2+ + NADPH)-induced lipid peroxidation in rat liver microsomal membranes and 6.5 times better protection of cytochrome P-450 against oxidative damage than d-alpha-tocopherol. To clarify the mechanisms responsible for the much higher antioxidant potency of d-alpha-tocotrienol compared to d-alpha-tocopherol, ESR studies were performed of recycling efficiency of the chromanols from their chromanoxyl radicals. 1H-NMR measurements of lipid molecular mobility in liposomes containing chromanols, and fluorescence measurements which reveal the uniformity of distribution (clusterizations) of chromanols in the lipid bilayer. From the results, we concluded that this higher antioxidant potency of d-alpha-tocotrienol is due to the combined effects of three properties exhibited by d-alpha-tocotrienol as compared to d-alpha-tocopherol: (i) its higher recycling efficiency from chromanoxyl radicals, (ii) its more uniform distribution in membrane bilayer, and (iii) its stronger disordering of membrane lipids which makes interaction of chromanols with lipid radicals more efficient. The data presented show that there is a considerable discrepancy between the relative in vitro antioxidant activity of d-alpha-tocopherol and d-alpha-tocotrienol with the conventional bioassays of their vitamin activity.

[Establishment of Wg3h-neo cell line with two genetic markers]

Plasmid PSV2-neo DNA containing neo gene (PSV2 neo) was successfully transferred into Wg3h cells, a HGPRT-Chinese hamster fibroblast cell line, by calcium phosphate DNA co-precipitating technique. Cells carrying two selectable markers (AGR and G418R) were thus obtained and passed for more than 40 generations, and designated as Wg3h-neo cell line. The existence of PSV2-neo sequences in the Wg3h-neo genome was confirmed by dot-blot hybridization with PSV2-neo DNA probe. Comparative studies showed that no significant difference in morphology, growth rate or genetic characteristics could be found between the Wg3h and Wg3h-neo cell lines.

Effects of two ACTH analogs on successive odor discrimination learning in rats

Olfactory discrimination learning has been shown to provide a powerful tool to investigate the mechanisms involved in the formation, storage and retrieval of information in rodent CNS. In the present study we tested the effects of two ACTH analogs, which were previously reported to influence the processes of learning and memory, on various olfactory learning tasks. The ACTH(4-9) analog HOE 427 produced an apparent increase in storage of olfactory information as shown by the difficulty experienced by the animals to rapidly reverse their behavioral responses to previously learned odors. Similarly, the ACTH (4-9) analog ORG 2766 appears to enhance the storage of olfactory information when administered either before or after the learning trials. These data are consistent with the notion that ACTH and related analogs facilitate performance in a variety of learning tasks. In addition, our results suggest possible mechanisms by which some neuroactive peptides might modulate learning and memory processes in the CNS.

[Protective effects of the pollen of Codonopsis pilosula (Franch.) Nannf. on liver lesions at the ultrastructural level]

The experimental hepatic lesion of C57 mice was induced by carbon tetrachloride (CCI4), and the feeds containing pollen of Codonopsis pilosula were given to the animals. It was found by electronic microscopy that these pollens evidently reduced the hepatic steatosis, improved liver necrosis, suppressed the formation of the collagen fibrils in Disse's spaces and around central veinules. It was shown that the pollens of Codonopsis pilosula could counteract efficiently the liver lesion of mice induced by CCI4.

[A case of clear cell carcinoma of the minor salivary gland]

A rare case of clear cell carcinoma of the palatal salivary gland in a 69-year-old man is reported. Histopathologically, nests and cords of tumor cells, which showed predominantly clear cytoplasms, and occasionally eosinophilic cytoplasms, proliferated on the overlying epithelium and capsules of the fibrous connective tissue. The clear cell cytoplasms were found to be PAS positive, diastase soluble, and Alcian-blue negative, indicating the presence of glycogen. Ultrastructurally, the tumor cells were found to contain glycogen and cytoplasmic filaments in various proportions. These observations suggest that clear cell carcinoma is myoepithelial in origin.