Substrate-dependent effect of acetonitrile on human liver microsomal cytochrome P450 2C9 (CYP2C9) activity

Acetonitrile is an organic solvent commonly used to increase the solubility of lipophilic substrates for in vitro studies. In this study, we examined its effect on four reactions (diclofenac hydroxylation, tolbutamide methyl hydroxylation, phenytoin hydroxylation, and celecoxib methyl hydroxylation) catalyzed by human liver microsomes and by the recombinant CYP2C9. In both cases, the effect of acetonitrile on activity was found to be substrate-dependent. Namely, it increased diclofenac 4'-hydroxylase and tolbutamide methyl hydroxylase activities, but decreased celecoxib methyl hydroxylase activity in a concentration-dependent manner. By comparison, hydroxylation of phenytoin was resistant to its effect. The presence of acetonitrile (3%, v/v) gave rise to a lower K(m) and a higher V(max) for diclofenac hydroxylase in both liver microsomes and recombinant CYP2C9 preparations (87 and 52% increase in V(max)/K(m) ratio, respectively). On the other hand, the inhibitory effect of the solvent (1%, v/v) toward celecoxib hydroxylase was characterized by a decrease in V(max) (human liver microsomes) or a change in both K(m) and V(max) (rCYP2C9), leading to 25 and 46% decrease in V(max)/K(m) for both systems. The results of this study underscore the need for careful evaluation of solvent effects before initiation of inhibition or cytochrome P450 reaction phenotyping studies.

Preliminary investigation of sequence-independent DNA binding proteins in rat skeletal muscle sarcoplasmic reticulum and their function

To observe the binding of plasmid DNA to non-nuclear DNA binding proteins in sarcoplasmic reticulum (SR) and the effects of this binding on SR function, sarcoplasmic reticulum proteins in rat skeletal muscle were isolated by differential centrifuge and sucrose density-gradient centrifuge. The results showed that there are two sequence-independent DNA binding proteins in SR proteins, the molecular weights of which are 83 and 58 ku, respectively. Ca(2+) uptake and release of SR were remarkably promoted by the binding of plasmid DNA to DNA binding proteins in SR, the mechanism is probably through increasing of Ca(2+)-ATPase activity in SR and changing of character of Ca(2+) release channel ryanodine receptors induced by the binding. These results suggest that there exist DNA binding proteins in SR and its binding to DNA may affect Ca(2+) transport of SR.

Vasoactive effects of adrenotensin and its interactions with adrenomedullin

OBJECTIVE

To investigate the vasoactive effects of adrenotensin and the interactions between adrenotensin and adrenomedullin (ADM).

METHODS

Isolated rat aortic tension, rat mean arterial pressure and 3H-TdR incorporation of rat vascular smooth muscle cells were measured. Isolated rat aortas were incubated in K-H solution containing adrenomedullin or adrenotensin. The released adrenotensin or adrenomedullin (in incubation medium) from rat aortas was measured by radioimmunoassay.

RESULTS

1 x 10(-8) and 1 x 10(-7) mol/L adrenotensin augmented rat aortic tension in a dose-dependent manner (P < 0.01). An intravenous bolus injection of adrenotensin (2.5 nmol/kg, i.v.) increased the mean arterial pressure by 28% in anesthetized rats (P < 0.01). 1 x 10(-7) mol/L adrenotensin increased 3H-TdR incorporation in cultured rat vascular smooth muscle cells by 55% (P < 0.01). Adrenomedullin inhibited these activities of adrenotensin to different extents. 1 x 10(-9), 1 x 10(-8) and 1 x 10(-7) mol/L adrenotensin decreased adrenomedullin release rates by 19%, 35% and 46%, respectively (P < 0.05 or P < 0.01) and 1 x 10(-8) mol/L adrenomedullin also inhibited adrenotensin release by 45% from rat aorta (P < 0.01).

CONCLUSION

Adrenotensin is a novel peptide that elicits the activities of vasoconstriction, pressor effects and induces the proliferation of vascular smooth muscle cells. There is antagonism in vascular activities and reciprocal inhibition in the release between adrenotensin and adrenomedullin. These interactions are manifestations of intramolecular regulation of proadrenomedullin (Pro-ADM).

[The inhibition of prourokinase gene transfer on deposition of platelets on rabbit carotid artery intima]

OBJECTIVE

To observe the expression of pro-urokinase (proUK) gene in rabbit carotid artery transfected with replication-deficient adenovirus vector containing proUK gene (Ad/prouk) and the deposition of platelet on the same injured vessel.

METHODS

Ad/proUK (Ad/proUK, 3 x 10(10) pfu/ml) was injected into the right carotid artery locally. Wild type adenovirus (Ad) was locally injected into the left carotid artery as self-control. The expression of proUK gene was investigated by immunohistochemistry assay. After injury of the gene-transfected vessel by electric stimulation, the deposition of (111) In-labeled platelet was quantitatively observed. The thrombosis was observed with HE-stained vessel section.

RESULTS

There were lots of proUK granules in the endothelium of Ad/proUK gene-transfected vessel. The differences in (111) In-platelets deposition per gram dry weight vessel segment were significant between Ad/proUK and Ad transfected control vessels [(4.60 +/- 0.93) x 10(7)/g vs control (27.95 +/- 4.93) x 10(7)/g, P < 0.01)]. The HE-stained vessel section showed that there were only small thrombi in proUK gene-transfected vessel but massive thrombi almost blocked up the whole vessel in control vessel.

CONCLUSION

The proUK gene-transfected vessel can obviously inhibit (111) In-labeled platelet deposition on injured vessel and thus thrombosis.

Biphasic redistribution of muscarinic receptor and the altered receptor phosphorylation and gene transcription are underlying mechanisms in the rat heart during sepsis

OBJECTIVE

The purpose of this study was to investigate intracellular redistribution of muscarinic cholinergic receptor (m2AChR) and the roles of receptor phosphorylation and gene transcription as underlying mechanisms in the rat heart during different phases of sepsis.

METHODS

Sepsis was induced by cecal ligation and puncture (CLP). The density of m2AChR in the sarcolemmal and light vesicle fractions was studied using [3H]-quinuclidinyl benzilate ([3H]-QNB). Phosphorylation of m2AChR was studied by labeling of the myocardial ATP pool by perfusing isolated hearts with [32P]H3PO4 followed by identification of the phosphorylated m2AChR with SDS-PAGE. The steady-state level of m2AChR mRNA was determined by RT-PCR and Southern blot analysis.

RESULTS

Septic rat hearts exhibit an initial hypercardiodynamic (9 h after CLP, early sepsis) and a subsequent hypocardiodynamic (18 h after CLP, late sepsis) state. During early sepsis, the Bmax for [3H]-QNB binding was increased in sarcolemma (+69%) but decreased in light vesicles (-22%), whereas during late sepsis, the Bmax was decreased in sarcolemma (-20%) but increased in light vesicles (+32%). The sum of Bmax for sarcolemmal and light vesicle fractions was increased during early sepsis (+43%) but decreased during late sepsis (-14%). The phosphorylation of m2AChR was decreased during early sepsis (-73%) but increased during late sepsis (+36% to +90%). The m2AChR mRNA abundance was increased during early sepsis (+52%) but decreased during late sepsis (-28%).

CONCLUSIONS

The m2AChR in the rat heart was externalized from light vesicles to sarcolemma (overexpression) during early sepsis but internalized from surface membranes to intracellular sites (underexpression) during late sepsis. Furthermore, changes in the receptor phosphorylation and gene transcription are responsible for the biphasic redistribution and the altered expression of m2AChR in the rat heart during the progression of sepsis.

Pacing in right ventricular dysplasia after disconnection surgery

This report describes a 33-year-old patient with arrhythmogenic right ventricular (RV) dysplasia who had a dual chamber pacemaker implanted at age 23 years for drug-induced bradycardia. Pacing was continued after right ventricular free-wall disconnection (RVFWD) at age 24 years. Her pacemaker was not replaced after battery depletion 7 years later. She presented the following year in severe right-sided heart failure. Her old pacemaker generator was replaced. This was followed by rapid resolution of her clinical failure and return to a full, active, physical lifestyle. This observation suggests the potential benefit of dual chamber pacing in patients with RV dysplasia after RVFWD.

Alternation of Na(+)-Ca2+ exchange in rat cardiac sarcolemmal membranes during different phases of sepsis

OBJECTIVE

To study the alteration of Na(+)-Ca2+ exchange in rat cardiac sarcolemmal membrane during phases of septic shock.

METHODS

Sepsis was induced by cecal ligation and puncture (CLP). Na(+)-Ca2+ exchange was assayed by radioactive analysis.

RESULTS

Na(+)-dependent 45Ca2+ uptake was decreased by 62%-69% in late phase of sepsis, whereas it was not affected in early phase of sepsis. Na(+)-Ca2+ exchange stimulated by 5' guanylyl imidodiphosphate [Gpp (NH) p] was decreased by 65.7% in late phase of sepsis but unaltered in early phase of sepsis. Two agonists (angiotensin II and phenylephrine) coupled to Gq and a protein kinase C activator, phorbol 12-myristate 13-acetate (PMA) all inhibited Na(+)-Ca2+ exchange in late phase of sepsis. Na(+)-Ca2+ exchange activities induced by phosphorylation of Na(+)-Ca2+ exchange were decreased in late phase of sepsis, whereas inhibition of Na(+)-Ca2+ exchange by dephosphorylation was increased both in early and late phases of sepsis.

CONCLUSION

The alteration of Na(+)-Ca2+ exchange during different phases of sepsis might be related to the activities of Gq, protein kinase C, and phosphorylation/dephosphorylation.

Association between delayed cardioprotection of aged rat myocytes and activation of mitogen-activated protein kinase

OBJECTIVE

To study the cardioprotective effects of hypoxic preconditioning (HPC) on aged rat ventricular myocytes and the cellular mechanism of protection.

METHODS

In the model of hypoxia/reoxygenation (H/R) of isolated ventricular myocytes of aged rat, the effects of HPC on aged rat ventricular myocytes against lethal H/R stimulated ischemia/reperfusion (I/R) injury 24 hours later and the changes of mitogen-activated protein kinase (MAPK) system were observed in the present study.

RESULTS

HPC attenuated the lactate dehydrogenase (LDH) release and ATP depletion in myocytes and increased the viability of myocytes. It was also found that MAPK and its down-stream kinase--S6 kinase were also activated after HPC.

CONCLUSION

There is delayed cardioprotection in cardiac myocytes of aged rat and the cellular mechanism underlying might involve the activation of MAPK system.

Design, synthesis, and evaluations of substituted 3-[(3- or 4-carboxyethylpyrrol-2-yl)methylidenyl]indolin-2-ones as inhibitors of VEGF, FGF, and PDGF receptor tyrosine kinases

Receptor tyrosine kinases (RTKs) have been implicated as therapeutic targets for the treatment of human diseases including cancers, inflammatory diseases, cardiovascular diseases including arterial restenosis, and fibrotic diseases of the lung, liver, and kidney. Three classes of 3-substituted indolin-2-ones containing propionic acid functionality attached to the pyrrole ring at the C-3 position of the core have been identified as catalytic inhibitors of the vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and platelet-derived growth factor (PDGF) RTKs. Some of the compounds were found to inhibit the tyrosine kinase activity associated with isolated vascular endothelial growth factor receptor 2 (VEGF-R2) [fetal liver tyrosine kinase 1 (Flk-1)/kinase insert domain-containing receptor (KDR)], fibroblast growth factor receptor (FGF-R), and platelet-derived growth factor receptor (PDGF-R) tyrosine kinase with IC(50) values at nanomolar level. Thus, compound 1 showed inhibition against VEGF-R2 (Flk-1/KDR) and FGF-R1 tyrosine kinase activity with IC(50) values of 20 and 30 nM, respectively, while compound 16f inhibited the PDGF-R tyrosine kinase activity with IC(50) value of 10 nM. Structural models and structure-activity relationship analysis of these compounds for the target receptors are discussed. The cellular activities of these compounds were profiled using cellular proliferation assays as measured by bromodeoxyuridine (BrdU) incorporation. Specific and potent inhibition of cell growth was observed for some of these compounds. These data provide evidence that these compounds can be used to inhibit the function of these target receptors.

Identification of S-(n-butylcarbamoyl)glutathione, a reactive carbamoylating metabolite of tolbutamide in the rat, and evaluation of its inhibitory effects on glutathione reductase in vitro

Tolbutamide (TOLB), a widely used hypoglycemic agent in the therapy of non-insulin-dependent diabetes mellitus, has been reported to be teratogenic and/or embryotoxic in several animal species and humans. It has been proposed that the teratogenic effects of TOLB are linked to drug-mediated depletion of glutathione (GSH) through inhibition of the enzyme glutathione reductase (GR), although the mechanism by which this inhibition occurs remains unknown. In the study presented here, rats were injected with TOLB (200 mg/kg ip), and bile was collected for analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS). This led to the identification of S-(n-butylcarbamoyl)glutathione (SBuG), a reactive GSH conjugate derived from n-butyl isocyanate, as a minor metabolite of TOLB in bile. Upon incubation of SBuG (0.25-1.0 mM) with GR from either yeast or bovine intestinal mucosa in the presence of NADPH (0.20 mM), enzyme activity was lost in a time- and concentration-dependent manner. No inhibition was observed when NADPH was omitted from incubations, or when the natural substrate for the enzyme, glutathione disulfide (GSSG, 0.05 mM), was added. TOLB itself did not inhibit GR over the concentration range of 0.8-2.0 mM. It is concluded that metabolic activation of TOLB in vivo leads to the generation of reactive intermediates (n-butyl isocyanate and SBuG) which carbamoylate and thereby inhibit GR. At critical periods of organogenesis, the resulting perturbation of GSH homeostasis in exposed tissues may play a key role in the teratogenic and/or embryotoxic effects of TOLB.

Nitric oxide synthase/nitric oxide pathway mediates intussusception pathogenesis in rats

OBJECTIVE

To study the role of nitric oxide synthase/nitric oxide pathway in the pathophysiological process of intussusception (IN).

METHODS

The IN model of rat was induced by lipopolysaccharide (LPS). The content of NOx in plasma and the NOS activity in colic smooth muscle tissues were measured. The content of cGMP was determined by radioimmunoassay.

RESULTS

LPS (10 mg/kg, i.p.) induced IN in up to 40% of the rats 6 hours after treatment with LPS. The incidence of IN was significantly increased by 58.3% (P < 0.05) and by 66.8% (P < 0.01) in L-arginine (L-Arg)-treated rats (2% in drinking water) and in sodium nitroprusside (NSP)-treated rats (1 mg/kg, i.p.), respectively, but it is significantly decreased by 66.8% (P < 0.01) after administration of M-omega-nitro-L-arginine methyl ester (L-NAME, 15 mg/kg, i.p.), an inhibitor of nitric oxide synthase (NOS) activity. Furthermore, LPS increased total NOS activity, NOx production and cGMP levels in plasma or in colic smooth muscle tissues. These parameters in LPS-IN rats were significantly elevated by 38.8%, 50.7%, and 48.7% respectively (P < 0.01) compared with LPS-non-IN rats.

CONCLUSION

NOS/NO pathway plays an important role in the process of IN, and inhibition of NO production may serve as a possible approach to prevent IN.

Role of a potent inhibitory monoclonal antibody to cytochrome P-450 3A4 in assessment of human drug metabolism

Cytochrome P-450 (CYP) 3A4 is an inordinately important CYP enzyme that catalyzes the metabolism of a vast array of clinically used drugs. Microsomal proteins of Spodoptera frugiperda (Sf21) insect cells infected with recombinant baculoviruses encoding CYP3A4 cDNA were used to immunize mice and to develop a monoclonal antibody (mAb(3A4a)) specific to CYP3A4 through the use of hybridoma technology. The mAb is both a potent inhibitor and a strong binder of CYP3A4. One and 5 microl (0.5 and 2.5 microM IgG(2a)) of the mAb mouse ascites in 1-ml incubation containing 20 pmol of CYP3A4 strongly inhibited the testosterone 6beta-hydroxylation by 95 and 99%, respectively, and, to a lesser extent, cross-inhibited CYP3A5 and CYP3A7 activity. mAb(3A4a) exhibited no cross-reactivity with any of the other recombinant human CYP isoforms (CYP1A1, CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP2E1) in the course of CYP reaction phenotyping and Western immunoblot analyses. The potency of mAb-induced inhibition is insensitive to substrate concentration in human liver microsomes. Therefore, mAb(3A4a) was used to assess the quantitative role of CYP3A4/5 to the metabolism of testosterone and diazepam in five human liver microsomes. The results showed that CYP3A4 and CYP3A5 contribute >95% to both testosterone 6beta-hydroxylation and diazepam 3-hydroxylation and 52 to 73% to diazepam N-demethylation, respectively. In addition, mAb(3A4a) significantly inhibited testosterone 6beta-hydroxylase activity in rhesus monkey liver microsomes to a degree equal to that observed with CYP3A4 in human liver microsomes. By comparison, no inhibition of testosterone 6beta-hydroxylase activity was observed in the presence of dog, rat, and mouse liver microsomes. The selectivity of ketoconazole, a chemical inhibitor of CYP3A4, was probed with mAb(3A4a) and was shown to be highly concentration dependent in the diazepam N-demethylation by human liver microsomes. The results demonstrate that inhibitory and immunoblotting mAb(3A4a) can offer a precise and useful tool for quantitative identification of CYP3A4/5 in the metabolism of drugs in clinical use and drugs in development.

Growth inhibition of psoriatic keratinocytes by quinazoline tyrosine kinase inhibitors

Psoriasis is characterized by hyperproliferation of keratinocytes associated with an inflammatory infiltrate in the epidermis. Among factors which may be related to hyperplasia of psoriatic keratinocytes is the persistent autocrine stimulation of the epidermal growth factor receptor (EGFR) by transforming growth factor-alpha. Owing to the pivotal role of the EGFR in driving the growth of human psoriatic keratinocytes, we examined two selective inhibitors of EGFR kinase activity: 4-(3-bromophenylamino)-6, 7-dimethoxyquinazoline (AG1517/SU5271) and 4-(3-chlorophenylamino)-6, 7-dimethoxyquinazoline (AG1478) on psoriatic keratinocytes. SU5271 potently inhibits ligand-induced autophosphorylation of EGFR, and downstream signal transduction events, including DNA replication and cell cycle progression. SU5271, at micromolar concentrations, inhibited the proliferation of keratinocytes isolated from psoriatic lesions in excellent correlation with its EGFR kinase inhibitory activity in these cells. Biologically active concentrations of SU5271 penetrated human cadaver skin, suggesting that this compound is a strong candidate as an antipsoriatic agent.

Non-suppressed conductivity and indirect UV detection of carboxylic acids in environmental samples by ion-exclusion chromatography using 2,6-pyridinedicarboxylic acidic eluent

2,6-Pyridinedicarboxylic acid (PDCA) was evaluated as an eluent for indirect UV and non-suppressed conductivity detection of carboxylic acids in ion-exclusion chromatography. The effect of PDCA concentration on the separation and detection sensitivity was investigated. The reasonable resolutions between carboxylic acids were achieved using 1 mM PDCA eluent. Detection limits were 1.0-7.0 microM for conductivity detection and 8-30 microM for UV detection. Compared to the eluent containing 1 mM sulfuric acid, the method offers a high resolution and high detection sensitivity for both detectors due to its high molar absorptivity and low background conductance. The proposed method was demonstrated to be useful for the determination of carboxylic acids in environmental samples with direct sample injection.

Molecular characterization and expression of mandibular organ-inhibiting hormone, a recently discovered neuropeptide involved in the regulation of growth and reproduction in the crab Cancer pagurus

Methyl farnesoate, the crustacean juvenoid, is synthesized and secreted from the mandibular organs of crustaceans under the negative control of the sinus gland-derived mandibular organ-inhibiting hormone (MO-IH). Previously we isolated and sequenced two isoforms, MO-IH-1 and MO-IH-2, differing by just one amino acid, from sinus glands of the edible crab, Cancer pagurus. We now report the isolation of cDNAs encoding MO-IH-1 and MO-IH-2 by a combination of reverse-transcriptase-mediated PCR in conjunction with 5' and 3' rapid amplification of cDNA ends ('RACE'). Full-length clones of MO-IH-1 and MO-IH-2 encoded a 34-residue putative signal peptide and the mature 78-residue MO-IH sequences. Northern blot analysis of various tissues showed that MO-IH expression is confined to the X-organ (a cluster of perikarya within the eye). Southern blot analysis indicated that there are approx. 10 copies of the gene for MO-IH in C. pagurus. Additional Southern blotting experiments detected MO-IH-hybridizing bands in another Cancer species, C. antennarius. In support of this, an HPLC-radioimmunoassay analysis of sinus gland extracts of C. antennarius and C. magister also revealed MO-IH-like immunoreactivity.

Factors affecting soil acidification under legumes. III. Acid production by N2 -fixing legumes as influenced by nitrate supply

Leaching of nitrate through soil profiles is a major cause of soil acidification. Legume species differ in their ability to take up nitrate (NO₃ ^- ) and in the degree to which soil NO₃ ^- impairs legume nodulation and N₂ fixation. This pot experiment examined species variation in N₂ fixation and acid production in grain legumes grown for 6 wk on a sandy soil with Ca(NO₃ )₂ added at 0-56.7 mg N kg^-1 soil. The eight legumes studied were Lupinus angustifolius ('Gungurru'), Lupinus albus ('Kiev mutant'), Lupinus luteus ('Teo'), Cicer arietinum (Selection T1587), Pisum sativum ('Dundale' and 'Wirrega'), Vicia faba ('Fiord') and Lathyrus sativus (Selection 453). While number of nodules was not significantly affected by treatment with NO₃ ^- , increasing supply of NO₃ ^- decreased nodule mass, with P. sativum'Wirrega' being most sensitive and C. arientinum and V. faba least sensitive. The concentrations of nitrogen in plants generally decreased as the supply of NO₃ ^- increased. Increasing supply of NO₃ ^- decreased the percentage of N₂ fixation, most significantly in L. sativus and least in L. albus. In the absence of added NO₃ ^- , the amounts of H⁺ produced per unit biomass (specific acid production) differed by as much as 2.2-fold among the species, with C. arientinum generating most H⁺ , followed by L. angustifolius, L. luteus, L. albus, V. faba, L. sativus, P. sativum'Dundale' and P. sativum'Wirrega'. This species variation was even greater at higher NO₃ ^- supply. In the presence of NO₃ ^- at up to 14.2 mg N kg^-1 , acid production by these legumes correlated well with uptake of excess cations but not with the concentration of nitrogen in plants. For all species, release of H⁺ declined with increasing supply of NO₃ ^- , decreasing most in L. sativus and least in C. arientinum. The results suggest that there might be scope for selecting grain legume species in order to minimize soil acidification by decreasing leaching of NO₃ ^- .

Prediction of antidepressant effects of sleep deprivation by metabolic rates in the ventral anterior cingulate and medial prefrontal cortex

OBJECTIVE

Sleep deprivation has been shown to have an antidepressant benefit in a subgroup of depressed patients. Functional imaging studies by the authors and others have suggested that patients with elevated metabolic rates in the anterior cingulate gyrus at baseline are more likely to respond to either sleep deprivation or antidepressant medications than patients with normal metabolic rates. The authors extend their earlier work in a larger group of patients and explore additional brain areas with statistical probability mapping.

METHOD

Thirty-six patients with unipolar depression and 26 normal volunteers were studied with positron emission tomography before and after sleep deprivation. Response to sleep deprivation was defined as a 40% or larger decrease in total scores on the Hamilton Depression Rating Scale.

RESULTS

One-third of the depressed patients had a significant response to sleep deprivation. Responders had higher relative metabolic rates in the medial prefrontal cortex, ventral anterior cingulate, and posterior subcallosal gyrus at baseline than depressed patients who did not respond to sleep deprivation and normal volunteers. Lower Hamilton depression scores correlated significantly with lower metabolic rates in the left medial prefrontal cortex. After sleep deprivation, significant decreases in metabolic rates occurred in the medial prefrontal cortex and frontal pole in the patients who responded positively to sleep deprivation.

CONCLUSIONS

High pretreatment metabolic rates and decreases in metabolic rates after treatment in the medial prefrontal cortex may characterize a subgroup of depressed patients who improve following sleep deprivation and, perhaps, other antidepressant treatments.

Transcriptional and posttranscriptional regulation of beta(2)-adrenergic receptor gene in rat liver during sepsis

Changes in beta(2)-adrenergic receptor (beta(2)-AR) gene expression in the rat liver during different phases of sepsis were studied. Sepsis was induced by cecal ligation and puncture (CLP). Septic rats exhibit two metabolically distinct phases: an initial hyperglycemic (9 h after CLP; early sepsis) followed by a hypoglycemic phase (18 h after CLP; late sepsis). The [(3)H]dihydroalprenolol binding studies show that the density of beta(2)-AR was decreased by 12 and 35% during the early and late phases of sepsis, respectively. Western blot analyses depict that the beta(2)-AR protein level was reduced by 37 and 72% during early and late sepsis, respectively. The reverse transcription polymerase chain reaction and Southern blot analyses reveal that the steady-state level of beta(2)-AR mRNA was decreased by 37% during early phase and 77% during late phase of sepsis. Nuclear run-off assays show that the rate of transcription of beta(2)-AR mRNA was reduced by 36% during early sepsis and 64% during late sepsis. The stability assays indicate that the half-life of beta(2)-AR mRNA was shortened by 21 and 50% during the early and late phases of sepsis, respectively, indicating that the rate of degradation of beta(2)-AR mRNA was progressively enhanced during sepsis. These findings demonstrate that the beta(2)-AR gene was underexpressed in the liver during the progression of sepsis, and, furthermore, the underexpression of the beta(2)-AR gene was the result of a reduction in the rate of transcription coupled with an enhancement in the rate of degradation of beta(2)-AR gene transcripts. Thus our findings that the transcriptional and posttranscriptional regulation of beta(2)-AR gene associated with decreases in beta(2)-AR number and its protein expression may provide a molecular mechanistic explanation for the development of hypoglycemia during the late stage of sepsis.

Modulatory effects of alveolar macrophages on CD4+ T-cell IL-5 responses correlate with IL-1beta, IL-6, and IL-12 production

Increasing evidence suggests that the pattern of T-cell cytokine production can be modulated by antigen presenting cell (APC)-derived factors during the cell interactions. Recently, it has been shown that alveolar macrophages (AMs) from atopic asthmatics (AA) but not atopic nonasthmatics (AN) enhance interleukin (IL)-5 production by CD4+ T-cells. The present study compared AM production of IL-1beta, IL-6, and IL-12, as well as their associated functional capacity to influence IL-5 production by allergen-specific CD4+ T-cells in 10 AA, 10 AN, and nine nonatopic control subjects (C). AMs from AA showed a relatively high production of IL-1beta and IL-6 (p<0.05) and a relatively low secretion of IL-12 compared to C, whereas AMs from AN and C behaved similarly. This study confirmed previous findings that co-culture with AMs augments IL-5 production from allergen-stimulated CD4+ T-cells only in AA and not in nonasthmatics even if they are atopic. On the other hand, stimulation with allergen alone did not enhance IL-5 production by CD4+ T-cells in either AA nor AN. AM-induced changes in CD4+ T-cell IL-5 production upon allergen stimulation significantly correlated with their ability to produce IL-1beta (r=0.59, p<0.01), IL-6 (r=0.56, p<0.01), and inversely with IL-12 (r=-64, p=0.002) in all atopic subjects, and even more closely with the ratio of IL-12/IL-1beta (r=-0.75, p<0.001) and IL-12/IL-6 production (r=-0.81, p<0.001) in these subjects. These findings suggest that the role of alveolar macrophages from atopic asthmatics in enhancing interleukin-5 production by allergen-specific CD4+ T-cells is due, at least partly, to their aberrant production of interleukin-1beta, interleukin-6, and particularly of interleukin-12.

Expression of caspase and BCL-2 apoptotic family members in mouse preimplantation embryos

Apoptosis, as determined by blastomere and DNA fragmentation, occurs in many preimplantation mouse embryos. To investigate which genes contribute to apoptosis in preimplantation embryos, we used the reverse transcription-polymerase chain reaction to assess mRNA levels for seven genes in the caspase family and seven genes in the BCL-2 family. All caspase mRNAs were detectable in oocytes, while expression in preimplantation embryos varied in a stage-specific manner. An assay for group II caspase enzymatic activity showed that although transcripts for these caspases could not be detected in zygotes, proteolytic activity could be detected in polar bodies, fragmented zygotes, and zygotes treated with staurosporine. This suggests that maternal caspases are inherited during oogenesis. Transcripts for some members of the BCL-2 family could be detected at every stage of preimplantation development. Transcripts for other members were rarely detected. When BCL-2 and BAX protein levels were assessed using immunofluorescence, both proteins were detected in zygotes and in blastocysts. When fragmented blastocysts were compared to normal blastocysts, levels of BCL-2 immunofluorescence tended to be lower in fragmented blastocysts. This result supports a model in which the ratio of BCL-2 to BAX is altered in apoptotic embryos.