HeJ Mice Research Articles

CECAL LIGATION AND PUNCTURE (CLP) INDUCES APOPTOSIS IN THYMUS, SPLEEN, LUNG, AND GUT BY AN ENDOTOXIN AND TNF-INDEPENDENT PATHWAY

Two challenges (intraperitoneal lipopolysaccharide (LPS) administration and cecal ligation and puncture (CLP)) and two strains of mice (LPS-normoresponder (C3H/HeN) and LPS-hyporesponder (C3H/HeJ)) were used to investigate pathways of cell injury. After intraperitoneal administration of LPS, endotoxin was absorbed into the bloodstream (HeN, 10.4 +/- 9.4 x 10(4) EU/mL; HeJ, 14.7 +/- 6.0 x 10(4) EU/mL), but as expected, only C3H/HeN mice produced serum tumor necrosis factor (TNF) (HeN, 2.5 +/- 2.0 x 10(3)pg/mL; HeJ, 87.0 +/- 38.7 pg/mL). Gel electrophoretic analysis of DNA extracted from six organs demonstrated the apoptotic "ladder" only in the thymus and only in the HeN mice. When the mice were challenged with CLP, both HeN and HeJ produced a small amount of serum TNF (HeN, 5.8 +/- 3.5 x 10(2) pg/mL; HeJ, 2.2 +/- 2.5 x 10(2) pg/mL) and both strains had very mild endotoxemia (HeN, 23.4 +/- 3.8 EU/mL; HeJ, 27.9 +/- 10.1 EU/mL). The DNA fragmentation pattern characteristic of apoptosis was observed not only in thymus but also in spleen, lung, and Peyer's patch of gut of both strains. This organ-specific pattern was more pronounced in the thymus of HeN mice; otherwise, the organ-specific patterns were similar for HeN and HeJ mice challenged by CLP but absent in those same organs when those same mice were challenged with LPS. The data suggest the existence not only of an endotoxin-driven activation for thymic apoptosis, but also of an endotoxin-independent, TNF-independent pathway activating widespread apoptosis in the murine CLP model of sepsis.

The effect of immunomodulation of stimulator antigen presenting cells on subsequent responder T-cell function

In this study, we examined whether lipopolysaccharide (LPS)-, interferon-γ (IFN-γ) or 16,16-dimethyl prostaglandin E 2 (dmPGE 2)-pretreatment of stimulator spleen cells from C57BL6 (B6) mice affects effector function of responder T-lymphocyte from C3H HeJ mice. Stimulation of B6-derived splenic mononuclear cells (SMNCs) with LPS (10 μg/ml) prior to their utilization as stimulator cells in a mixed lymphocyte culture (MLC) resulted in an increase in responder T-lymphocyte proliferation compared to utilization of unstimulated SMNC ( P < 0.05). IFN-γ demonstrated similar effects in a dose dependent fashion with maximal stimulatory effect seen at 1000 U/ml. In contrast, pretreatment of stimulator SMNC with dmPGE 2 resulted in dose-dependent inhibition of the responder T-lymphocyte proliferation with maximum inhibitory effect seen using a concentration of dmPGE 2 of 10 −5 M. The presence of indomethacin in the MLC did not reverse this effect. These data demonstrate the effect of immunomodulation of stimulator spleen cells on subsequent T-lymphocyte function.

Chronic low-dose UVA irradiation induces local suppression of contact hypersensitivity, Langerhans cell depletion and suppressor cell activation in C3H/HeJ mice.

It has previously been demonstrated that chronic low-dose solar-simulated UV radiation could induce both local and systemic immunosuppression as well as tolerance to a topically applied hapten. In this study, we have used a chronic low-dose UV-irradiation protocol to investigate the effects of UVA on the skin immune system of C3H/ HeJ mice. Irradiation with UVA + B significantly suppressed the local and systemic primary contact hypersensitivity (CHS) response to the hapten 2,4,6-trinitrochlorobenzene. Furthermore UVA + B reduced Langerhans cell (LC) and dendritic epidermal T cell (DETC) densities in chronically UV-irradiated mice. Ultraviolet A irradiation induced local, but not systemic, immunosuppression and reduced LC (32%) but not DETC from the epidermis compared to the shaved control animals. Treatment of mice with both UVA + B and UVA radiation also induced an impaired secondary CHS response, and this tolerance was transferable with spleen cells. These results suggest that depletion of LC, but not DETC, may be involved in UVA-induced local immunosuppression in our model, and that tolerance was induced in the presence of normal numbers of DETC. Hence exposure of C3H/HeJ mice 5 days per week for 4 weeks with UVA can induce local immunosuppression and tolerance.

Oxidant stress responses in influenza virus pneumonia: gene expression and transcription factor activation.

The pathogenesis of influenza virus infections of the lungs is in part mediated by oxidative stress. Such infections might therefore be expected to induce expression of stress-response genes and genes encoding antioxidant enzymes and to activate transcriptional regulatory proteins. Mice (C57B1/6 and C3H/HeJ) were infected intranasally with influenza virus A/PR/8/34 (H1N1). Expression of the genes encoding the antioxidant enzymes manganese superoxide dismutase (Mn- SOD), indoleamine-2, 3-dioxygenase (IDO), heme oxygenase-1, and glutathione peroxidase were increased in the lungs of virus-infected animals. Cu/ZnSOD and catalase mRNA were not induced by viral infection. Activation of the transcriptional regulatory proteins AP-1, C/EBP, and NF-kappa B (which are known to be affected by oxidant stress) was demonstrated by electrophoretic mobility shift assay after viral infection. In the case of MnSOD, despite increased gene expression enzyme activity was not increased. In contrast, for heme oxygenase-1 both mRNA and activity were increased. C3H/ HeJ and C57B1/6 mice, which are known to have different responses to other types of oxidant stress, also differed in their responses to viral infection. Induction of heme oxygenase-1 expression was greater in C57B1/6 mice than in C3H/ HeJ mice, although inhibiting this enzyme did not alter virus-induced mortality. In contrast, IDO was more strongly induced in C3H/HeJ mice. Activation of NF-kappa B was much more marked in C57B1/6 mice than in C3H/HeJ mice. Although virus replication and inflammatory responses were equivalent in the two strains, lung injury (as measured by wet-to-dry wt ratios) and mortality were greater in C3H/HeJ mice than in C57B1/6 mice, a difference that may be related to differing oxidant stress responses. Thus influenza pneumonia causes an oxidant stress response in the lungs, the nature of which is determined in part by the genetic background of the host.

Altering culture conditions reveals strain-related differences in activity and immunoreactive isoforms of 3β-hydroxysteroid dehydrogenase-isomerase in mouse Leydig cells

We previously reported that 3β-hydroxysteroid dehydrogenase-isomerase (3βHSD) activity is higher in Leydig cells from C57BL 6J mice than those from C3H HeJ mice. This study examines whether the differences in 3βHSD activity in Leydig cells from the two strains of mice are due to the expression of different 3βHSD isoforms and if a specific isoform corresponds with the amount of 3βHSD activity under various culture conditions. Leydig cells were plated in Waymouth's + 15% horse serum (HS) medium. Some culture were terminated 24 h later after plating (day 1) and assayed for 3βHSD activity or immunoreactivity. The remaining cultures were maintained in HS or changed to serum-free medium. We demonstrate for the first time that two 3βHSD immunoreactive isoforms are expressed in freshly isolated Leydig cells and those cultured for 1 day. The same two 3βHSD isoforms are detectable in both strains. Thus, the previously reported strain-related differences in 3βHSD activity are not due to the expression of different isoforms. When cultured for 8 days, the higher molecular weight 3βHSD immunoreactive band is no longer detectable in Leydig cells from either strain. When maintained in HS, 3βHSD activity in C57BL 6J Leydig cells decreases significantly by day 8, while 3βHSD activity in C3H HeJ Leydig cells does not change through day 8. When Leydig cells were cultured in serum-free medium, 3βHSD activity is maintained in cultured Leydig cells from C57BL 6J and significantly increases in C3H HeJ 3βHSD by day 8. These data suggest that HS has a strain-specific inhibitory effect on 3βHSD activity, causing a significant decrease in C57BL 6J 3βHSD activity and preventing an increase in C3H HeJ . Densitometric analysis reveals a correspondence between changes in 3βHSD activity and the lower molecular weight isoform but not the higher molecular weight isoform. Treatment with cAMP induces the immunoreactive mass of the lower molecular isoform but not the higher molecular isoform of 3βHSD. Currently, it is unclear what the function of the higher molecular weight 3βHSD isoform is in mouse Leydig cells.

Experimental gut-derived endotoxaemia and bacteraemia are reduced by systemic administration of monoclonal anti-LPS antibodies

This study aimed to investigate the effects and mechanisms of action of systemic administration of monoclonal antibodies, anti-endotoxin (HA-1A), in an animal model of gut-origin sepsis. In the first experiment, Balb c mice were transfused with allogeneic blood ( C3H HeJ mice). Five days post-transfusion the animals were gavaged with 1 × 10 9 Escherichia coli and randomized into three groups ( n = 22 each) to receive a sham burn (SB group) or a 20 per cent TBSA thermal injury, immediately followed by the systemic administration of monoclonal antibodies (3 mg/kg) (HA-1A group) or aliquots of sterile saline (Control group). The animal survival rate was observed for 10 days poslburn. In the second experiment transfusion and burn injury were reproduced but the mice ( n = 8/group) were gavaged with 10 9 E.coli labelled with 111indium oxine. Four hours after the burn the mesenteric lymph nodes, liver, lungs and blood were harvested to determine plasma endotoxin levels and the magnitude of translocation of labelled bacteria measured by the residual radioactivity in the organs. Circulating endotoxin levels were determined by limulus assay. The mortality rate of the HA-1A group (9 per cent) was similar to the SB group (0 per cent) and significantly lower than the control group (59 per cent) ( P < 0.05). Both plasma endotoxin levels and degree of bacterial translocation in all extraintestinal tissues were significantly lower (by approximately 50 per cent) in the HA-1A group than in the control group ( P < 0.05). Systemic administration of HA-1A exerts a beneficial effect by reducing the circulating levels of endotoxin and by increasing the gut barrier function to translocating microorganisms.

Strain difference in jejunal crypt cell susceptibility to radiation-induced apoptosis.

Levels of radiation-induced jejunal crypt cell apoptosis were compared in C57BL/6J, C3Hf/Kam and C3H/HeJ mice. Apoptosis levels were consistently lower in the C3H strains than in C57BL/6J. Although other explanations are possible, the strain difference is most likely to have a genetic basis, and in fact a preliminary analysis of the F2 progeny of C3H/HeJ and C57BL/6J mice indicates that more than one gene is involved. Both C3H strains also had lower levels of radiation-induced thymocyte apoptosis than C57BL/6J mice. Jejunal crypt cell apoptosis levels did not co-segregate with thymocyte apoptosis levels in the F2 progeny of C57BL/6J and C3H/HeJ mice. These results imply that the genes responsible for the difference in radiation-induced thymocyte apoptosis levels between these two strains are not the same as those responsible for the strain difference in radiation-induced jejunal crypt cell apoptosis levels. The experiments reported here identify strain-specific differences in levels of radiation-induced crypt cell apoptosis and are a first step towards identifying genetic polymorphisms that influence sensitivity of the small intestine to damage from ionizing radiation.

Inhibition of Growth of a Murine Squamous Cell Carcinoma by a Cyclooxygenase Inhibitor Increases Leukotriene B4 Production

To determine the role of metabolites of arachidonic acid in the growth of squamous cell carcinomas of the head and neck. Investigation of the effect of a cyclooxygenase inhibitor, piroxicam, on the growth of squamous cell carcinoma in a murine model. C3H/HeJ mice bearing squamous cell carcinoma (SCCVII) were treated with piroxicam (0.08 mg/d, orally) for 30 days beginning 1 day before tumor inoculation. Decrease in tumor volumes and tumor growth rates. Significant inhibition of tumor growth (P = .002) and final tumor weight (P = .0007) was noted in the group receiving piroxicam therapy. Prostaglandin E2 levels in the tumor tissue were unrelated to treatment or tumor size. Increased levels of leukotriene B4 were observed in the piroxicam-treated group (P = .03), and larger tumors were associated with decreased leukotriene B4 levels (P = .0001). Cyclooxygenase inhibitors may be effective in the treatment of some squamous cell carcinomas. The therapeutic effect of cyclooxygenase inhibitors may result from shunting into the lipoxygenase pathway of arachidonic acid metabolism.

Efficacy of Coxiella burnetii and its chloroform-methanol residue (CMR) fraction against Rift Valley fever virus infection in mice

Strains of Coxiella burnetii phase I and II whole cells (WC-I and WC-II) or whole cell fractions were assessed for their potential to induce long-lasting protection in endotoxin-non-responder C3H HeJ or CD-1 mice against Rift Valley fever (RVF) virus challenge. Among the whole cell fractions, only the chloroform-methanol residue (CMR), administered as a single dose (100 μg per mouse) 24 h before viral challenge, effectively protected 100% of the mice from RVF virus; the CMR of the Ohio strain of C. burnetii was not protective. Most of the RVF virus-infected mice treated with other C. burnetii cell fractions died, although their times to death varied. Lipopolysaccharide (LPS) associated with CMR preparations used in these studies, did not protect against RVF virus challenge. A single dose of 100 μg of CMR given 24 h before viral challenge completely eradicated 4-t logs of RVF virus in the serum, liver, spleen, and central nervous system. Compared to several other immunomodulators, CMR was an equally effective antiviral agent. Efficacy of CMR of both Henzerling and Ohio strains disappeared or was marginal when treatment was initiated 2–3 days before RVF viral challenge, even when a second or a third dose of CMR was administered after challenge. A single dose of liposome-encapsulated CMR to RVF virus-infected mice extended the range of therapeutic efficacy of this biologically active component of C. burnetii to 4 days before infection.

Cytokines induced in vitro by Mycoplasma mycoides ssp. mycoides, large colony type

Septicemic disease in goats and sheep caused by the large colony type of Mycoplasma mycoides ssp. mycoides has clinical and pathological features in common with septic endotoxemia. We studied the ability of the mycoplasma to induce mediators of biological responses to endotoxin, such as TNFα, IL-1α, IL-6 and nitric oxide. Heat-killed suspensions of mycoplasmas in a concentration of 25 μg protein ml −1 induced all mediators in macrophages from peritoneal cavity and bone marrow of both C3H HeN (LPS responsive) and C3H HeJ (LPS low-responsive) mice. Lipopolysaccharide (LPS) in a concentration of 100 ng ml −1 induced the mediators in C3H HeN derived macrophages, only. Simultaneous stimulation of macrophages with interferon-γ enhanced the secretion of nitric oxide (measured as nitrite) but not the cytokines. We conclude that heat-killed Mycoplasma mycoides ssp. mycoides, large colony type, has cytokine inductive activity similar to bacterial endotoxin, but with an induction mechanism different from LPS.

Endotoxin and tumour necrosis factor do not cause mortality from caecal ligation and puncture

Macrophage tumour necrosis factor-alpha (TNF-α) production is thought to represent an important pathogenic mechanism by which Gram-negative sepsis is mediated. We compared the effects of caecal ligation and puncture (CLP) on endotoxin-sensitive ( C3H HeSnJ ) and endotoxin-resistant ( C3H HeJ ) mice. Mortality after CLP for C3H HeSnJ mice compared with C3H HeJ mice was not significantly different (32% and 55%, respectively). When survivors were injected with lipopolysaccharide intraperitoneally on the 7th day after CLP, the mortality rate was 82% for C3H HeSnJ mice versus 0% for C3H HeJ mice ( P < 0.0001). Serum endotoxin levels at 24 h after CLP were only slightly elevated. Serum TNF levels and peritoneal macrophage TNF production were undetectable in C3H HeJ mice and were only slightly elevated in C3H HeSnJ mice by 24 h after CLP. Peritoneal macrophage mRNA levels for TNF-α, IL-1β, and I-Aα displayed a similar pattern in the two strains of mice, with a 2- to 3-fold increase in TNF-α and IL-1β mRNA levels by 24 h and a sharp decrease in I-Aα mRNA by 24 h. The cause of mortality in mice that undergo CLP cannot be attributed to overwhelming endotoxemia and/or TNF production.

Cytokine regulation of parathyroid hormone-related protein messenger ribonucleic acid levels in mouse spleen: paradoxical effects of interferon-gamma and interleukin-4.

Under normal physiological conditions, PTH-related protein (PTHrP) is produced in a wide variety of tissues and is thought to act locally in an autocrine or paracrine fashion more analogous to cytokines than to classic hormones such as PTH. In addition, we have recently shown that, like cytokines, PTHrP is induced in the spleen during the response to sublethal doses of endotoxin [lipopolysaccharide (LPS)] an effect that is mediated by tumor necrosis factor (TNF). As complex cytokine cascades are induced in response to infectious or inflammatory stimuli, the effects of other prototypical inflammatory [interferon-gamma (IFN gamma)] or antiinflammatory [interleukin-4 (IL-4)] cytokines on PTHrP gene expression were studied. Paradoxically, IFN gamma (50 micrograms), a cytokine that usually synergizes with TNF, inhibited LPS induction of splenic PTHrP messenger RNA (mRNA) levels in LPS-sensitive C3H/OuJ (OuJ) and LPS-resistant C3H/HeJ (HeJ) mice. The stimulation of splenic PTHrP mRNA levels caused by the administration of TNF alpha or interleukin-1 beta was similarly inhibited by IFN gamma, a type II interferon. In contrast, IFN alpha (50 micrograms), a type I interferon, stimulated splenic levels of PTHrP mRNA. IL-4, a prototypical antiinflammatory cytokine, also had a paradoxical effect on LPS induction of splenic PTHrP mRNA levels. Instead of inhibiting LPS induction of splenic PTHrP mRNA levels in OuJ or HeJ mice, IL-4 (200 ng) actually stimulated PTHrP mRNA levels. These complex cytokine interactions suggest that the expression of PTHrP in response to infectious or inflammatory stimuli depends on the counterbalancing effects of the specific cytokine networks induced by each stimulus.

Cytokine regulation of parathyroid hormone-related protein messenger ribonucleic acid levels in mouse spleen: paradoxical effects of interferon-gamma and interleukin-4

Under normal physiological conditions, PTH-related protein (PTHrP) is produced in a wide variety of tissues and is thought to act locally in an autocrine or paracrine fashion more analogous to cytokines than to classic hormones such as PTH. In addition, we have recently shown that, like cytokines, PTHrP is induced in the spleen during the response to sublethal doses of endotoxin [lipopolysaccharide (LPS)] an effect that is mediated by tumor necrosis factor (TNF). As complex cytokine cascades are induced in response to infectious or inflammatory stimuli, the effects of other prototypical inflammatory [interferon-gamma (IFN gamma)] or antiinflammatory [interleukin-4 (IL-4)] cytokines on PTHrP gene expression were studied. Paradoxically, IFN gamma (50 micrograms), a cytokine that usually synergizes with TNF, inhibited LPS induction of splenic PTHrP messenger RNA (mRNA) levels in LPS-sensitive C3H/OuJ (OuJ) and LPS-resistant C3H/HeJ (HeJ) mice. The stimulation of splenic PTHrP mRNA levels caused by the administration of TNF alpha or interleukin-1 beta was similarly inhibited by IFN gamma, a type II interferon. In contrast, IFN alpha (50 micrograms), a type I interferon, stimulated splenic levels of PTHrP mRNA. IL-4, a prototypical antiinflammatory cytokine, also had a paradoxical effect on LPS induction of splenic PTHrP mRNA levels. Instead of inhibiting LPS induction of splenic PTHrP mRNA levels in OuJ or HeJ mice, IL-4 (200 ng) actually stimulated PTHrP mRNA levels. These complex cytokine interactions suggest that the expression of PTHrP in response to infectious or inflammatory stimuli depends on the counterbalancing effects of the specific cytokine networks induced by each stimulus.

Role for monokines in the metabolic effects of endotoxin. Interferon-gamma restores responsiveness of C3H/HeJ mice in vivo.

To examine the role of cytokines in mediating the lipogenic effects of endotoxin (LPS), we studied the effects of LPS and cytokines on hepatic fatty acid synthesis in LPS-sensitive C3H/OuJ mice and in LPS-resistant C3H/HeJ mice, whose macrophages are defective in the ability to produce tumor necrosis factor (TNF) and IL-1 in response to LPS. HeJ mice were 16-fold less sensitive than OuJ mice to the lipogenic effect of LPS. In OuJ mice, 10 micrograms of LPS caused a maximal increase in hepatic lipogenesis (3.86 +/- 0.41-fold), whereas in HeJ mice the maximal increase was only 1.79 +/- 0.32-fold after 100 micrograms of LPS. This lipogenic response paralleled the decreased ability of LPS to increase hepatic and splenic levels of mRNAs for TNF and IL-1 and serum levels of TNF in HeJ mice. In contrast, the maximal effect of TNF on lipogenesis was greater and the sensitivity to TNF was increased 2.4-fold in HeJ mice compared to OuJ mice. Administration of IFN-gamma before LPS in HeJ mice had no effect on IL-1 mRNA, but partially restored the LPS-induced increase in hepatic and splenic mRNA for TNF and serum TNF levels, which may account for the partial restoration of sensitivity to the lipogenic effect of LPS after IFN-gamma treatment. These results indicate that cytokines produced by mononuclear leukocytes mediate the lipogenic effects of LPS.

Conditioned stress responses by pregnant and/or lactating mice reduce immune responses of their offspring after weaning

C3H HEJ mice repeatedly exposed to rotational stress (45 rpm for 30 min) show a decreased immune response after challenge with sheep erythrocytes (SRBC) or multiple minor histoincompatible skin grafts (B10.BR) in association with the cues present when initially exposed to the physical stress. This conditioned immunosuppression is associated with diminished antibody production and enhanced skin graft survival. When previously conditioned mice were mated with normal (nonconditioned) males and reexposed to conditioning cues during pregnancy (days 13, 16, and 19 of gestation), the offspring of these mice were also found to produce a decreased antibody response (and decreased skin graft rejection response) when tested at 7 weeks of age. This altered immune response in the offspring occurred in the absence of any deliberate direct manipulation of these mice. In a further study a reciprocal crossover design was used to investigate whether altered immunity in the offspring was dependent upon the treatment of the biological mother and/or the fostering mother. The most marked immunosuppression was seen in offspring born to, and fostered on, conditioned mothers reexposed to cues previously associated with physical stress. However, even the offspring of normal C3H HEJ matings developed a reduced immune response if they were fostered on conditioned mothers reexposed to stress-associated cues. These data imply that the developing immune system is regulated by factors in the colostrum/feto-placental unit which are modified by conditioning phenomena.

Regulation of cytochrome P450 IID by acute phase mediators in [formula omitted] mice

Cytochrome P450 IID6 is a drug metabolizing enzyme and the major target antigen in LKM-1 antibody positive chronic active hepatitis. The histological hallmark of chronic active hepatitis is a lymphocytic infiltrate in the liver. It is unknown whether and how cytokines produced and secreted by these tissue infiltrating mononuclear cells regulate the cellular expression of cytochrome P450 IID6. To study the effect of interleukin 1, tumor necrosis factor and interleukin 6 on the hepatocellular RNA expression of cytochrome P450 IID, we injected each of the cytokines in C3H HeJ mice. We found a time-dependent suppression of the cytochrome in the liver. Six hours after the intraperitoneal injection of 0,5 μg interleukin 1 beta the specific RNA-expression was reduced to 25% of the original level. A similar reduction was found after the injection of 2 μg tumor necrosis factor alpha. A mild suppression to 65% of the orginal level was seen six hours following the dose of 100 ng interleukin 6. Our studies show how immune mediators can change the expression of an autoantigen. Further studies in the human system are necessary to estimate this regulation for the elimination of drugs and in LKM-1 antibody positive chronic active hepatitis.

Platelet-activating factor induces intestinal necrosis, but not septic shock, in germ-free and specific-pathogen-free rodents

Platelet-activating factor (PAF) was injected into conventional mice, endotoxin-resistant mice (C3H/HEJ), conventional rats, germ-free rats and specific-pathogen-free (SPF) mice. The PAF resulted in significant necrosis and damage to the small intestines of all the animals tested. In general, the frequency and severity of the lesions were similar in all groups. All the conventional rats and mice, as well as the endotoxin-resistant HEJ mice, were dead 18 h after the injection of the PAF, while all the germ-free rats and the SPF mice survived. These data demonstrate that development of massive intestinal lesions, in the absence of aerobic bacteria, is not sufficient to cause the death of the host from septic shock and endotoxaemia.

Nucleoside uptake in macrophages from various murine strains: A short-time and a two-step stimulation model

Kinetics of [ 3H]-uridine uptake by murine peritoneal macrophages (pMφ) is early altered after exposure to a variety of stimuli. Alterations caused by Candida albicans , lipopolysaccharide (LPS) and recombinant interferon-γ (rIFN-γ) were similar in SAVO, C57BL 6 , C3H HeN and C3H HeJ mice, and were not correlated with an activation process as shown by the amount of tumor necrosis factor-α (TNF-α) being released. Short-time exposure to all stimuli resulted in an increased nucleoside uptake by SAVO pMφ, suggesting that the tumoricidal function of this cell either depends from the type of stimulus or the time when the specific interaction with the cell receptor is taking place. Experiments with priming and triggering signals confirmed the above findings, indicating that the increase or the decrease of nucleoside uptake into the cell depends essentially on the chemical nature of the priming stimulus. The triggering stimulus, on the other hand, is only able to amplify the primary response.

A fluorinated 2-nitroimidazole, ku-2285, as a new hypoxic cell radiosensitizer

To develop new hypoxic cell radiosensitizers, we incorporated fluorine atoms into the side chain of the 2-nitroimidazole. Of the resulting compounds, KU-2285 (a 2-nitroimidazole with an N 1-substituent of CH 2CF 2CONHCH 2CH 2OH) was considered the most useful as a hypoxic cell radiosensitizer. In this study, its in vivo radiosensitizing activity and acute toxicity were compared with those of etanidazole. The reduction potentials of KU-2285 and etanidazole were −0.96 V and −1.05 V vs Ag Ag + in N,N-dimethylformamide, respectively, and their respective octanol/water partition coefficients were 0.25 and 0.040. The in vivo radiosensitizing activity of KU-2285 was found to be similar to that of etanidazole at the same administration dose when assayed by an in vivo-in vitro assay, a growth delay assay, and a tumor control assay using SCC VII tumor or transplanted mammary tumor in C3H He mice. Although the radiosensitizing activity of etanidazole was reduced when it was administered orally, there was no significant difference in the radiosensitizing activity of KU-2285 whether it was administered intravenously, intraperitoneally, or orally. The acute toxicity measured as the LD 50 7 in 8-week-old female C3H HeJ mice was found to be 2.4 g/kg (intravenously), 2.1 g/kg (intraperitonealy), and 4.25 g/kg (orally) for KU-2285, whereas it was 4.75 g/kg (intravenously) for etanidazole.

Stressor-induced alteration of lymphocyte proliferation in mice: Evidence for enhancement of mitogenic responsiveness

The present study evaluated the immunomodulatory effect of the administration of different intensities of electric foot shock presentations to different strains of mice. The results showed an enhancement of the mitogenic responsiveness to concanavalin A (Con A), a T-lymphocyte mitogen, that was directly related to the intensity of the electric shock presentations. However, the electric shock induced no significant alteration of the mitogenic responsiveness to lipopolysaccharide (LPS), a B-lymphocyte mitogen. These findings were evident in HLA-SW/ICR, 57BL 6N , and C3H HEJ mice. In contrast, the C3H HEN mice did not show any alteration of mitogenic responsiveness. The number of splenic leukocytes was not altered by the electric shock presentations in the strains that showed enhanced mitogenic responsiveness, but the C3H HEN strain showed a leukopenia directly related to the shock intensity. In a subsequent experiment, it was demonstrated that repeated sessions of electric shock resulted in a reduction in the enhancement effect. Collectively, the results demonstrate that stressful stimulation can result in an enhancement of mitogenic responsiveness, but that such an effect is dependent on the intensity and frequency of the stressor, as well as on the strain of the subject.