We developed a novel fluorometric assay method for the measurement of glycosyltransferase activities using mono- and di-saccharides aminated and tagged with 7-hydroxycoumarin-3-carboxylic acid (coumarin) as substrates, N-acetylglucosamine (GlcNAc)-coumarin for β1, 4-galactosyltransferase from boivne milk and Galβ1-4GlcNAc-coumarin for α2, 3- and α2, 6-sialyltransferases from rat liver. Using Galβ1-3GlcNAc and Galβ1-4Glc-NAc-coumarin, α1, 3/4- and α1, 3-fucosyltransferase activities were also determined, respectively. These enzymatic products liberated by the reactions of glycosyltransferases in the presence of sugar nucleotides, were separated by a normal phase or an ion-pair reversed phase HPLC with an isocratic elution and fluorescence detection. We applied this assay method to determine the glycosyltransferase activities in 8 kinds of human tumor cell lines, including the cell lines derived from hepatocytes (HuH-7, HepG2), colonic cells (Colo205, HT-29), myelocytes (HL-60, U-937), B-lymphocytes (Daude) and T-lymphocytes (Jurkat). This assay method is accurate and easy compared with other isotopic and non-isotopic assay methods, and is sensitive enough to measure glycosyltransferase activities in cell homogenates.
A rapid and convenient method for N-linked oligosaccharide structure analysis was developed and applied to the quality examination of commercially manufactured recombinant human erythropoietin (rEPO). Oligosaccharides released from rEPO expressed in Chinese hamster ovary cells were labeled with 2-aminobenzamide, and analyzed by a combination of diethylaminoethyl (DEAE) column HPLC and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). This newly developed method allowed us to analyze sialylated oligosaccharides directly. The results showed that these oligosaccharides are composed of neutral-mono-di-tri-tetrasialyl oligosaccharides in a ratio of<1 : 2 : 13 : 34 : 51%, and that the core structure was a mixture of complex type bi-, tri- and tetra-antennary forms with one to three polylactosaminyl chains. Further analysis showed clearly that the N-linked oligosaccharide structure of rEPO has not changed throughout the past ten years of manufacturing by our company. The analysis was carried out using a small quantity (1 nmol) of rEPO, demonstrating the efficacy of the newly developed method. Further, the N-linked oligosaccharides of rEPO manufactured by our company almost coincided with those of the erythropoietin European Pharmacopoeia Biological Reference Preparation (Eur.Ph.BRP), a standard product.
The binding of human mannose-binding lectin (MBL) to human colon adenocarcinoma cell lines and leukemia cell lines was analyzed by flow cytometry using specific antibodies against MBL. MBL binding was observed in 3 of 7 colon adenocarcinoma cell lines (Colo205, Colo201 and DLD-1), but not in any of 3 leukemia cell lines tested. The binding of MBL to these cell lines was suger-specific and calcium-dependent, since it was almost completely inhibited in the presence of 10mM EDTA or 50mM mannose. The MBL binding to Colo205 cells was more strongly reduced by the pretreatment of the cells with an O-linked glycosylation inhibitor, benzyl-2-acetamide-2-deoxy-α-galactopyranoside (Bz-α-GalNAc), rather than an N-linked glycosylation inhibitor, tunicamycin. The degree of MBL binding was well correlated with the expression of Lewis A and Lewis B antigens on these cell lines. Moreover, MBL binding to Colo205 cells was inhibited by anti-Lewis A and anti-Lewis B antibodies. These results suggest that MBL could bind to some human colon adenocarcinoma cell lines through their Lewis A and Lewis B moieties.
Endothelium growth suppressing and tumor-regressing activities were copurified from the conditioned medium of P388D1 culture in the presence of 100μg/ml carboxymethylated curdlan by a procedure including ammonium sulfate fractionation and six column chromatographies of ceramic hydroxyapatite, Q-Sepharose, Sephacryl S-300 HR, Matrex PBA-30, PBE94, and anti-bovine serum albumin (anti-BSA) agarose. The intravenous administration of the purified growth suppressing factor for endothelial cells to sarcoma 180-bearing mouse caused a rapid decrease in the number of viable tumor cells in tumor lumps within 16h. Immunohistochemical study showed that the intravenous injection of the purified factor to sarcoma 180-bearing mouse resulted in hemorrhagic disorder all over the tissue in the tumor lamp. Thus, the purified factor exhibited not only growth suppressing activity for endothelial cells but also tumor regressing activity at a concentration as low as about 15 ng/mouse. The purified factor significantly inhibited in vitro tubulogenesis of bovine artery, human umbilical vein, and adult human darmal microvascular endothelial cells on collagen gel at a concentration of about 5 ng/ml. After the tube formation of endothelial cells was completed on a collagen gel, the purified factor disrupted the tubes at a concentration of about 5 ng/ml within 48 h. These findings demonstrate that endothelium growth suppressing factor is a potent inhibitor of angiogenesis as well as the growth of endothelial cells, and may bring about the regression of a solid tumor by inhibiting angiogenesis.
Structure-activity relationships of tetrandrine, isolated from a Kampo medicine, Stephania tetrandrae S. MOORE (root), and related synthetic compounds, were investigated in in vitro fetal bovine serum (FBS)-stimulated angiogenesis of cultured choroids in streptozotocin-diabetic Wistar rats, and air-pouch granuloma angiogenesis in vivo in diabetic mice. Tetrandrine, KS-1-1 (6, 7-dimethoxy-1-[[4-[5-(6, 7-dimethoxy-2-methyl-1, 2, 3, 4-tetrahydroisoquinolinyl)methyl-2-methoxy]phenoxy]benzol]-2-methyl-1, 2, 3, 4-tetrahydroisoquinoline), and KS-1-4 (6, 7-dimethoxy-1-[[4-[4-(6, 7-dimethoxy-2-methyl-1, 2, 3, 4-tetrahydroisoquinolinyl)methyl]phenoxy]benzyl]-2-methyl-1, 2, 3, 4-tetrahydroisoquinoline), potently inhibited choroidal angiogenesis and air-pouch granuloma angiogenesis in the diabetic state. Their inhibitory effects on diabetic choroids were greater than those on normal choroids. Among these compounds, KS-1-4 inhibited only diabetic angiogenesis. These compounds significantly inhibited FBS-stimulated tube formation in vascular endothelial cells from normal rats. Tetrandrine and KS-1-4, but not KS-1-1, inhibited vascular endothelial growth factor- and platelet-derived growth factor-BB-stimulated angiogenesis in normal choroids. The bis[tetrahydroisoquinoline] moiety, connected by oxy-bis[phenylenemethylene]and 2, 2'-diemthyl groups in tetrandrine, contribues to the inhibition of diabetic choroidal angiogenesis. KS-1-4 may be a candidate for anti-choroidopathy and retinopathy drugs in the diabetic state.
Anandamide (N-arachidonoylethanolamine) and six fatty acid ethanolamides were synthesized and their pharmacological effects in mice were assessed using catalepsy, hypothermia and pentobarbital-induced sleep prolongation as indices. The effects of phenylmethysulfonyl fluride (PMSF) pretreatment on anandamide effects were also evaluated and discussed in relation to inhibition of anandamide amidohydrolase in mouse brain and liver. The cataleptogenic effect of anandamide (ED50=6.0 mg/kg, i.v.) was 4 to 6 times more active than those of N-oleoyl-(ED50=26.5 mg/kg, i.v.) and N-linoleoylethanolamine (ED50=37.5 mg/kg, i.v.), although the peak time in the effect was observed within 1 min after i.v. administration. None of the saturated fatty acid ethanolamides (N-myristoyl-, N-palmitoyl-, N-stearoyl- and N-arachidoylethanolamine) showed a positive response in the cataleptogenic effect even at a dose up to 40 mg/kg i.v. Anandamide, N-linoleoyl-, N-oleoyl- and N-myristoylethanolamine (10 mg/kg, i.v.) produced a significant hypothermia (0.19 to 0.59°C) at 5 to 15 min after administration. The duration of the effects of these ethanolamides was also relatively short. Anandamide, N-linoleoyl-, N-oleovl- and N-palmitoylethanolamine (5 or 10 mg/kg, i.v.) significantly prolonged pentobarbital-induced sleeping time by 148-207% of control sleeping time. The cataleptogenic effect of anandamide was markedly potentiated by pretreatment of mice with PMSF (100 mg/kg, i.p.). The ED50 (mg/kg, i.v.) of anandamide was 0.48 (0.24-0.96) in PMSF-pretreated mice. The pretreatment of mice with PMSF significantly decreased the metabolic clearance rate of anandamide in microsomal fractions of liver and brain. Thus, the Vmax/Km values of brain and hepatic microsomes were 26 and 10%, respectively, as compared with those of control mice. The present study demonstrated that anandamide and N-acylethanolamines of unsaturated fatty acids exhibited cannabinoid-like effects in mice, and that anandamide amidohydrolase has an important role in the pharmacological effects of anandamide in vivo.
We have synthesized several 1α, 25-dihydroxyvitamin D [1α, 25(OH)2D] derivatives and evaluated their biological activity in terms of their binding affinity for the vitamin D receptor (VDR) and vitamin D-binding protein(DBP), antiproliferative ro differentiation-inducing effects on human promyelocytic leukemic HL-60 cells, and transcriptional activity on a rat 25-hydroxyvitamin D3-24-hydroxylase gene promoter, including two vitamin D-responsive elements (VDREs), and human osteocalcin gene promoter, including a VDRE in transfected human osteosarcoma MG-63 cells. Furthermore, human VDR- or retinoic acid X receptor α (RXRα)-mediated luciferase activities of the derivatives were also measured by a one-hybrid system in human epitheloid carcinoma, cervix HeLa cells and African green monkey kidney CV-1 cells. Binding affinity for VDR, bone-resorbing activity, antiproliferative and cell-differentiating effects, transactivation potencies on target genes and VDR- or RXRα-mediated gene regulations of 1α, 25(OH)2D2 and 1α, 25(OH)2D4 were almost comparable to the effects of 1α, 25(OH)2D3 while 24-epi-1α, 25(OH)2D2 and 1α, 25(OH)2D7 were much less active than 1α, 25(OH)2D3 in these respects. This is the first report concerning biological assessment of 1α, 25(OH)2D2, 1α, 25(OH)2D3, 1α, 25(OH)2D4, 24-epi-1α, 25(OH)2D2 and 1α, 25(OH)2D7 at the molecular level, especially with regards to the structural differences at the 24R- or 24S-methyl group and a double bond between carbons 22 and 23 in the side chain of 1α, 25(OH)2D derivatives.
In screening for antitumor constituents in traditional crude drugs, we used three cultured cell lines : mouse leukemia P388 cells, doxorubicin-resistant P388 cells and leczyme (catalytic lectin)-resistant P388 cells. The hot water extract (HWE) of the bark of Nikko maple (Acer nikoense) showed concentration-dependent inhibitory effects on the growth of these three cell lines. DNA fragmentation and morphological changes, accompanied by condensed and fragmented nuclei, were observed in the leukemina cell lines cultured with HWE of the bark of Nikko maple. Treatment with this HWE increased the expression of sialylated glycoconjuagtes on the apoptotic cells. These results suggest that HWE induces cell death via apoptosis in vitro.
We studied here the effect of 3 kinds of kampo-hozais (Shofu-san, Ji-zuso-ippo and Unsei-in) on the induction of oral tolerance to ovalbumin (OVA) in C3H/HeN mice by measuring serum levels of OVA-specific antibodies. Oral tolerance was induced by a single administation of OVA (2 or 20 mg, p.o.) 7d before the immunization.Among these kampo-hozais, mice administered Ji-zuso-ippo for 7d before feeding of 2 mg OVA had significantly lower levels of anti-OVA IgG and IgG1, and further, Ji-zuso-ippo tended to reduce anti-OVA Igs in 20 mg OVA-fed mice, whereas Ji-zuso-ippo did not alter anti-OVA Igs in non-OVA-fed mice. Unsei-in also slightly augmented the suppression of anti-OVA IgG and IgG1 ; however, this lowering action of Unsi-in should be due to its immunosuppressive effect. Shofu-san did not alter these anti-OVA Ig levels in serum. These results suggested that Ji-zuso-ippo could augment the induction of oral tolerance.
To determine the antidiabetic mechanism of Bakumondo-inshi (BI), we examined its effects on glucose absorption, α-glucosidase activity, sodium-dependent glucose transporter and facilitative glucose transporter isoform 5 (GLUT5) in small intestine. The oral administration of BI into KK-Ay mice caused a significant decrease in the glucose absorption in small intestine. The small intestine content of active glucose transporter isoform (SGLUT) protein content from KK-Ay mouse significantly decreased in the BI-treated KK-Ay mice compared to that in the controls. However, the small intestine content of facilitative glucose transporter isoform, GLUT5 protein content did not change. The α-glucosidase activity in small intestine significantly decreased in the BI-treated KK-Ay mice. These results suggest that the antidiabetic effect of BI is derived, at least in part, from a decrease of glucose absorption in small intestine, due to the reduction of SGLUT protein content in total membrane of the small intestine and the reduction of α-glucosidase activity. Because of its therapeutic mechanism BI could be a new category of therapeutic agent for non-insulin dependent diabetic mellitus.
We previously isolated berberine from aqueous extracts of tsu-kan-gan, a Kampo formula used for the treatment of osteoporosis. Berberine caused an inhibitory effect on parathyroid hormone (PTH)-stimulated bone resorption in neonatal mouse bone. In this report we describe the inhibitory effect of berberine on the formation of osteoclast-like multinucleated cells (OCLs) in the co-culture of mouse osteoblastic cells and bone marrow cells in the presence of 1α, 25-dihydroxyvitamin D3 [1α, 25(OH)2D3], PTH and interleukin-1α (IL-1α). Berberine dosedependently inhibited the formation of tartrate-resistant acid phosphatase (TRAP)-positive OCLs induced by 1α, 25 (OH)2D3, PTH and IL-1α. We prepared OCLa in the co-culture of osteoblastic cells and bone marrow cells. The effect of berberine on pit formation by OCLs was examined using dentin slices. As OCLs are terminally differentiated multinucleated calls, the survival of OCLs affects the bone-resorbing activity of OCLs. This prompted us to count the number of TRAP-positive OCLs on the slices. Berberine dose-dependently inhibited pit formation and caused a decrease in the number of TRAP-positive OCLs. Calctinin (CT) inhibited pit formation without affecting the number of OCLs. Berberine accelerated the cell death in OCLs cultivated on a culture plate, but CT did not affect the cell death of OCLs. This suggestes that the decrease in the number of OCLs on dentin slices may be due to apoptotic cell death in OCLs. In fact, Hoechst 33258 staining revealed that the treatment of OCLs with berberine resulted in condensed nuclei and a decrease in cell size. Oral administration of the berberine (30 and 50 mg/kg/d) to ovariectomized ras prevented a decrease in bone mineral density (BMD) of the lumber vertebra without affecting the weight of the uterus and plasma concentration of estradiol. These results suggested that berberine prevented a decrease in BMD in vivo by inhibiting osteoclastic bone resorption.
Berberine is the main ingredient of Coptis spp. This study selected berberine as a model drug to design a transdermal delivery system for the treatment of cutaneous leishmaniasis. Berberine was incorporated into chitosan hydrogel to prepare ointments. The physicochemical properties of the ointments and the release profile of berberine were investigated. The results indicated that the viscosity of chitosan hydrogel increased with an increasing amount of lactic acid or EDTA. The effect of EDTA on the viscosity was greater than that of lactic acid. By differential scanning calorimetry (DSC) measurement, no interaction was found to occur between chitosan and the soluble berberine. The release rate of berberine was inversely proportional to ointment viscosity. In in vitro skin perfusion studies, only trace amounts of berberine permeated through the rat skin due to its low oilwater partition coefficient. Surfactants were used as penetration enhancers to increase the percutaneous absorption of berberine. Among the enhancers, benzalkonium chloride was found to be the most efficient. Additionally, Tween 80 could increase the loading amount of berberine in the skin.
The effects of fatty acid glycerol esters and Tweens on the intestinal transport of ceftibuten were studied using a diffusion chamber system. The apparent permeation coefficient (Papp) was used as an index of the mucosal permeability to ceftibuten. The Papp markedly increased by the addition of hexaglycerol monostearate (HGMS) or hexaglycerol sesquistearate (HGSS) under an H+-gradient condition, while hexaglycerol tristearate (HGTS) and Tweens showed no effect on the absorptive ceftibuten permeability. These result are in agreement with those obtained in the previous study in the brush-border membrane vesicles. On the other hand, in the absence of an H+-gradient, the S-to-M transport of ceftibuten was proven to be significantly higher than the M-to-S one. In addition, either ATP-depletion of the mucosa or the addition of probenecid proved to enhance significantly the permeability of ceftibuten. These findings suggest the existence of an active secretory transport system for ceftibuten in the jejunal mucosa. To estimate potential effects of glycerol esters on efflux pumps as well as peptide transporters, the mucosal-to-serosal (M-to-S) and serosal-to-mucosal (S-to-M) permeability in the presence of the esters was further examined. HGMS, HGSS and HGTS markedly enhanced the M-to-S but not the S-to-M transport in the ATP-depleted jejunum without an H+-gradient, in which conditions contributions of both peptide transporter and efflux pump should be substantially small. HGMS and HGSS significantly enhanced the M-to-S ceftibuten transport in the ATP-depleted jejunum with an H+-gradient (p<0.01 vs. M-to-S transport without surfactant under the same conditions). Whereas, these glycerol esters were fround hardly to affect the P<app> of the S-to-M transport. These results indicate that the enhanced intestinal transport of ceftibuten due to the glycerol esters may be based on their effects on peptide transporters but neither on efflux pumps nor on the passive permeation routes.
Enhancement of skin distribution of propylene glycol (PG) in the skin by high purity cis-unsaturated fatty acids with different alkyl chain lengths was studied in the rat using Fourier transform/attenuated total rellection (FT-IR/ATR) analysis. Two fatty acids with the double bond at the Δ9 position, palmitoleic acid (ω7, Δ9) and oleic acid (ω9, Δ9), enhanced PG flux into the dermis and increased the dermal steady state level of PG. In contrast, myristoleic acid (ω5, Δ9) was extremely weak in its action. A positional effect of the ω chain was observed. The rate of skin structural alteration increased in proportion to ω chain length. The application of three fatty acids with the double bond at the ω9 position, oleic acid (ω9, Δ9), gondoic acid (ω9, Δ11), erucic acid (ω9, Δ13) enhanced PG distribution in the skin. While, nervonic acid (ω9, Δ15) did not increase PG distribution in the skin. The relationship of the Δ/ω ratio to parameters characterizing the action of enhancers (PGpeak area max, Tmax alteration, and the slope) sugest that skin distribution increases as the position of the double bond is shifted toward the hydrophilic end. It is therefore likely that the ratio of the Δ/ω chain length of the cis-unsaturated fatty acid determines the efficacy of these compounds as skin penetration enhancers. An adequate molecular volume may be required for cis-unsaturated fatty acids to act as enhancers.
The plasma concentration, total radioactivity and in vivo α1-adrenoceptor binding in rat tissues after intravenous (i.v.) injection of [3H]tamsulosin were measured and they were compared with those obtained after the injection of [3H]prazosin. The plasma concentration of [3H]tamsulosin was consistently higher than that of [3H]prazosin, with 1.4 times greater areas under the curve (AUC0-∞) of plasma concentration. As there was a significantly lower value of apparent volume of central compartment (Vdc) and distribution volume at steady state(Vdss) for [3H]tamsulosin than [3H]prazosin with little difference in elimination rate constant (β), the higher concentration of [3H]tamsulosin in plasma might be associated mainly with the smaller volume of distribution. The ratio of total radioactivity in tissues to the plasma unbound concentration of [3H]tamsulosin after i.v. injection of the ligand was consistently lower than that of [3H]prazosin. These observations suggest that [3H]tamsulosn is distributed in rat tissues in a more limited manner than [3H]prazosin. A significantly lower level of in vivo specific binding of [3H]tamsulosin than [3H]prazosin was observed in the spleen, heart and liver. Further, the apparent dissociation constant (Kd) and maximal number of binding sites (B<max>) for in vivo specific [3H]tamsulosin binding were considerably lower than those for [3H]prazosin binding. Therefore, these findings suggest that [3H]tamsulosin labels preferentially a subpopulation of the α1-adrenoceptor sites in rat tissues labeled by [3H]prazosin. In conclusion, the present study has shown that there is a significant difference in the pharmacokinetics and in vivo α1-adrenoceptor binding characteristics between tamsulosin and prazosin.
The effect of inescapable footshock stress on open-field activity, as measured by the number of ambulations, was studied in male mice. Ambulations significantly increased after footshock stress, the most significant effect appeared after 20 min-stimulation and the effect decreased as footshock time lengthened. The footshock stressinduced enhancement of ambulation was inibited by haloperidol (0.2, 0.5 and 1 mg/kg), phentolamine (5 and 10 mg/kg), mianserin (20mg/kg), atropine (0.5, 1 and 2 mg/kg), naltrexone (10 mg/kg) and MK-801 (0.05, 0.1 and 0.2 mg/kg), but was not influenced by propranolol (5, 10 and 20 mg/kg) or diazepam (1, 2 and 5 mg/kg). Haloperidol (0.5 and 1 mg/kg) and mianserin (5, 10 and 20 mg/kg) also exerted an inhibitory effect on non-stressed normal mice. These results suggest that dopaminergic, α-adrenergic, cholinergic, opioidergic and N-methyl-D-aspertate (NMDA) receptor-mediated neurotransmission systems are involved in the footshock stress-induced ambulatory activation.
Poncirin was isolated from water extract of the fruits of Poncirus trifoliata and metabolized by human intestinal bacteria. The inhibitory effect of poncirin and its metabolites by these bacteria on the growth of Helicobacter pylori (HP) was investigated. Among them, ponciretin (5, 7-dihydroxy-4'-methoxyflavanone), the main metabolite most potently inhibited the growth of HP, with a minimum inhibitory concentration (MIC) of 10-20 μg/ml. However, poncirin and its metabolites except ponciretin did not inhibit the growth of HP, nor did they inhibit HP urease.
Intranasal administration of diazepam may be a practical alternative to the conventional acute medication of seizures, such as status epilepticus. Nine healthy students participated in an open crossover study on intranasal versus intravenous administration of diazepam (2 mg). Blood samples were collected, pharmacodynamic tests were performed, and the volunteers filled out questionnaire. Peak concentration was achieved after 18±11 min and the bioavailability was 50.4±23.3%. A pharmacodynamic effect was observed after about 5 min, but the dose, even for i.v. administration, was too low to generate a strong measurable effect. The results indicate that intranasally administered diazepam may be an effective alternative to i.v. administration in relief of seizures, e.g. in an acute situation when a physician or nurse is not available on location.
The present paper investigates the pharmacokinetics of etoposide (VP-16) and carboplatin (CBDCA) in plasma and the cerebrospinal fluid (CSF), in the space left by tumor removal, of patients with glioma. Eight Japanese patients with glioma received a course of hyperosmotic disruption of the blood-brain barrier(HODBBB) and intraarterial combination chemotherapy with 60 mg/m2 of VP-16 and 300 mg/m2 of CBDCA. Allpatients were initially administered mannitol, followed by infusion of the anticancer drugs into the right internal carotid artery. Blood samples and samples of CSF in the space left by tumor removal were obtained. VP-16 and CBDCA concentration were measured by HPLC, and the pharmacokinetic parameters of these drugs estimated in CSF and plasma.The plasma concentrations of VP-16 and CBDCA peaked at the end of infusion, then decreased in a bi-exponential decay pattern during the remainder of the treatment period. Both VP-16 and CBDCA were detectable in CSF beginning 0.5h after the initiation of each infusion, and were then slowly eliminated from the space left by tumor removal. The mean maximum CSF concentration of VP-16 and CBDCA was 0.17 and 15.25% of that in plasma, respectively. The mean area under the time-CSF concentration curve from 0 to 24 h after VP-16 and CBDCA infusion was 1.91 and 113.6% of plasma, respectively. In two of the eight patients, the clinical response to treatment was a partial response and other patients showed no change. HODBBB and intraarterial combination chemotherapy with VP-16 and CBDCA may be useful in patients with brain tumors for maintenance chemotherapy.
E5531 is a specific lipid A antagonist and is expected to be a drug for the treatment of septic shock. The LAL (limulus amebocyte lysate) activity and pyrogenicity of E5531 were determined. The LAL activity of E5531 is large and confirmed that E5531 had a high affinity to the lipopolysaccharide receptor. The pyrogenic activity of E5531 is weak and the pyrogenic profile of E5531 is different from that of USP (United States Pharmacopoeia) reference standard endotoxin (ETX). E5531 suppressed the pyrogenicity of ETX in rabbits, indicating that E5531 in expected to be useful for the treatment of fever induced by ETX.
A significant sex-related difference was observed for the pharmacokinetics of acetohexamide in Wister-Imamichi (Wistar-IM) rats. However, there was no sex difference of the in vitro reductive metabolism of acetohexamide in the liver or kidney of these rats. Testectomy was found to decrease the plasma clearance (CLp) of acetohexamide in male rats, whereas ovariectomy had no effect on the CLp of acetohexamide in female animals, suggesting that androgens regulate the pharmacokinetics of acetohexamide. The co-administration of sulfamethazine, which is known to be metabolized by a male-specific cytochrome P450 (CYP) isoform (CYP2C11), significantly decresed the CLp of acetohexamide in male Wister-IM rats. Based on these results, it is reasonable to assume that the sex-dependent pharmacokinetics of acetohexamide observed in Wister-IM rats is associated with the male-specific hydroxylation catalyzed by CYP2C11.
Human myeloid leukemia K562 cells can be induced to differentiate to mature cells bidirectionally, i.e., hemin induces erythroid differentiation, while 12-O-tetradecanoylphorbol 13-acetate (TPA) induces differentiation to monocytes. TPA is also a potent inducer of heme oxygenase (HO), which catabolizes heme to biliverdin. We show here that TPA suppresses hemin-induced erythroid differentiation of K562 cells, while retinoids augment it. Further, an HO inhibitor, tin protoporphyrin (SnPP), suppresses TPA-induced K562 cell differentiation to monocytes. It was also found that co-treatment of K562 cells with SnPP and TPA induces erythroid differentiation of K562 cells, though SnPP alone or TPA alone does not induce erythroid differentiation, suggesting a role of HO in the directional switch of differentiation.