[Mycosis fungoides terminating in acute myelocytic leukemia]

A 57-year-old woman was admitted to our hospital with suspected leukemia in September 1999. In 1990, systemic erythema had occurred, and mycosis fungoides (MF) had been diagnosed by skin biopsy. Interferon-gamma therapy had not been effective, and the erythema had disappeared after treatment with psoralen and ultraviolet A (PUVA) therapy (1.46 J/cm2). The patient had subsequently done well with a course of topical steroids. On admission this time, the WBC count was 1,600/microliter with 6% blasts. The total nucleated cell count in a bone marrow aspirate was 43.1 x 10(4)/microliter, of which 86.2% were peroxidase-positive blasts. Acute myelocytic leukemia (AML) was diagnosed. Chromosomal analysis demonstrated abnormalities of 48, XX, +4, +8, +add(10)(p11), add(11)(q23) in 10 of 20 cells, and 51, idem, +6, +8, +21, +mar in 8 cells with mixed-lineage leukemia gene rearrangement. Therapies (radiation, chemotherapy and PUVA) for MF, and the altered immune response seen in patients with this disease, especially in the more advanced stages, collectively termed cutaneous T-cell lymphoma (CTCL), suggest that such patients may be at increased risk of a second primary malignancy. To our knowledge, AML has been reported in 8 MF patients including the present one. Attention should be given to the possibility of MF terminating in AML.

Syntheses, structures, and properties of tetrakis(mu-acetato)dirhodium(II) complexes with axial pyridine nitrogen donor ligands with or without assistance of hydrogen bonds

Eight adducts of Rh2(O2CCH3)4 with axial pyridine derivatives that contain hydrogen-bonding amino and/or steric methyl substituents in the 2- and 6-positions have been prepared and examined by electronic absorption and 1H NMR spectroscopy in solution and by elemental, IR, thermogravimetric, and X-ray diffraction analyses in the solid state. The results indicated that strong hydrogen bonding interactions between Rh2(O2CCH3)4 and axially coordinated pyridine derivatives with a 2- or 6-amino group occur in both solution and the solid state and contribute to the higher thermal stability of the molecular assembly of dirhodium complexes. It was demonstrated that such a combination of coordinate and hydrogen bonds is useful as a building tool in designing and constructing new organic-inorganic hybridized compounds and supramolecular architectures.

Sterol 14-demethylase P450 (CYP51) provides a breakthrough for the discussion on the evolution of cytochrome P450 gene superfamily

Biodiversity is the most characteristic feature of cytochrome P450. Finding of CYP51 distributing widely in biological kingdoms provided breakthroughs for the discussion on the evolution and diversification of P450. Molecular phylogenetic analysis demonstrated that CYP51 appeared in the prokaryotic era and distributed into most kingdoms concomitant with phylogenetic divergence. This is the first evolutionary evidence indicating the prokaryotic origin of P450. Modification of substrate specificity of eukaryotic CYP51s occurred independently to adapt to the different sterol precursors existing in each kingdom. Formation of CYP51 variants through the mutation of active site and the selection of the advantageous ones from them were demonstrated by the emergence of azole-resistant CYP51s in Candida albicans under the environments rich in azole antifungal agents. These findings illustrate the most probable core process of P450 diversification consisting of modification of active site and selection of the resulting variants through interaction with endogenous and exogenous chemicals.

Insulin is the essential factor maintaining the constitutive expression of hepatic sterol 14-demethylase P450 (CYP51)

The role of serum insulin in regulating the expression level of hepatic sterol 14-demethylase P450 (CYP51) was examined. Administration of streptozotocin, which destroys pancreatic beta-cells, caused reduction of CYP51 mRNA level in rats in parallel with the loss of serum insulin. Streptozotocin treatment also reduced the CYP51 activity. The decreased mRNA level and activity of the streptozotocin-treated rats were restored to the normal level within 24 h by repeated administration of insulin. CYP51 level of normal rats was insensitive to the circadian variation of serum insulin and insulin administration, and no significant difference was observed between the hepatic CYP51 activities of Sprague-Dawley and Wistar lean rats, although the serum insulin concentration of the latter was higher than the former. These facts indicate that the expression of hepatic CYP51 is maintained by serum insulin, and its lowest physiological level is sufficient for supporting the expression of CYP51. The responses of CYP51 expression to streptozotocin and insulin treatments were closely similar to those of the sterol regulatory element binding protein (SREBP)-1c expression [Shimomura et al. (1999) Proc. Nat. Acad. Sci. USA 96, 13656-13661]. Based on this fact, the possible contribution of SREBP-1c to the insulin-dependent expression of hepatic CYP51 gene was also discussed.

Dietary sugar beet fiber prevents the increase in aberrant crypt foci induced by gamma-irradiation in the colorectum of rats treated with an immunosuppressant

We demonstrated recently that gamma-irradiation can induce aberrant crypt foci (ACF) in the rat colorectum. The aim of this study was to evaluate the effect of dietary sugar beet fiber (SBF) on the distribution of the CD8(+) intraepithelial lymphocyte (IEL) in the colorectum and on the number of gamma-irradiation-induced ACF of rats administered anti-asialo GM1 (alpha AGM1) as an immunosuppressant. Wistar/ST rats fed a fiber-free diet or the diet supplemented with SBF (100 g/kg diet) were administrated alpha AGM1 or normal rabbit serum as a control during the initiation period with gamma-irradiation. At 5 and 9 wk after the first irradiation, ACF and total aberrant crypts (AC) per area in the colorectum were counted. The numbers of ACF (P = 0.0010) and AC (P = 0.0635) per unit area were lower in the SBF-fed group than in the rats fed the fiber-free diet. alpha AGM1 administration significantly raised the number of ACF (P = 0.0001) and AC (P = 0.0006) per area in the colorectum. Moreover, alpha AGM1 administration during the initiation period reduced the number of CD8(+) IEL per 100 cells in the epithelial layer (P = 0.0001) of the colon. These results demonstrate that reduction of the number of CD8(+) IEL per 100 cells in the epithelial layer as a result of alpha AGM1 administration promotes the formation of irradiation-induced ACF in the colorectum. The number of CD8(+) IEL per 100 cells in epithelial layer was lower in the group fed the fiber-free diet than in the SBF-fed group (P = 0.0522). These results indicated that the ingestion of dietary SBF suppressed gamma-irradiation-induced ACF formation through the immune surveillance in the colorectal mucosa.

Supplementation of orotic acid to the casein, but not to egg protein, soy protein, or wheat gluten diets, increases serum ornithine carbamoyltransferase activity

Effects of dietary supplementation of orotic acid to a diet containing the casein protein were compared with diets containing egg protein, soy protein, or wheat gluten on lipid levels in the liver and serum and activities of ornithine carbamoyltransferase (OCT) and alanine aminotransferase in the serum of rats. We found that supplementation of orotic acid to each diet increased the contents of the liver total lipids, triacylglycerol, and phospholipids compared with those not supplemented. The contents of liver total lipids, triacylglycerol, cholesterol, and phospholipids in rats fed the casein diet were significantly higher than those of rats fed the other three diets when orotic acid was supplemented. The levels of triacylglycerol, cholesterol, and phospholipids in the serum of rats fed the casein diet were markedly decreased by addition of orotic acid. The supplementation of orotic acid significantly increased the activities of both serum OCT and alanine aminotransferase in rats fed the casein diet, but not in rats fed the other diets. In conclusion, liver lipid accumulation induced by dietary orotic acid depends on the type of dietary protein. The enhancement of serum OCT activity may result from liver lipid accumulation in rats fed the casein diet supplemented with orotic acid, demonstrating hepatic damage.

Dynamic analyses on induced-fit gaseous guest binding to organic crystals with a quartz-crystal microbalance

The inclusion behavior of gaseous guest molecules in a solid apohost, an orthogonal anthracene-bis(resorcinol)tetraol (1), was investigated with a quartz-crystal microbalance (QCM). Compound 1 forms crystals composed of molecular sheets bound together by an extensive hydrogen-bonded network. An apohost of 1 was cast onto a QCM and the binding of gaseous guest molecules was followed as a function of time by observing the decrease in the oscillation frequency, which is directly related to the increase in mass. Ethyl acetate and methyl ethyl ketone were significantly included into the apohost, whereas benzene and cyclohexane were simply adsorbed onto the surface of the solid; all these guests have similar vapor pressures at 25 degrees C. On the other hand, a host analogue 2, a tetramethoxy derivative of 1, barely included these guest molecules. The inclusion amount and the rate of inclusion of ethyl acetate or methyl ethyl ketone showed a drastic increase above a threshold concentration of guests in the gas phase. Thus, the structure of the apohost changed cooperatively in order to bind guest molecules above the threshold guest concentration. This cooperativity of the binding behavior was kinetically analyzed.

Suppressive effect of excess dietary histidine on the expression of hepatic metallothionein-1 in rats

The gene expression of liver metallothionein-1 in excess dietary histidine was investigated by feeding rats ad libitum on either a basal or histidine-excess (50 g of L-histidine per kg of diet) diet for 5 d. The copper content of the liver and zinc level in the serum of the rats fed on the histidine-excess diet were lower by 21% and 61%, respectively of the figures for the rats fed on the basal diet, but the zinc content of the liver and copper level in the serum were not affected. Excess dietary histidine caused an increase in the urinary output of both copper and zinc. The level of liver metallothionine-1 mRNA was markedly lower at 19% in the rats fed on the a histidine-excess diet compared to the level with the basal diet. It thus appears that such a response by the level of liver metallothionein-1 mRNA might have been be due to the lower content of liver copper.

Increased intestinal calcium absorption from the ingestion of a phosphorylated guar gum hydrolysate independent of cecal fermentation in rats

The Apparent calcium absorption was increased in rats fed on P-GGH and GGH. However, this increase in calcium absorption from GGH feeding was cancelled by a cecectomy, whereas the corresponding increase from P-GGH feeding was not. The change in femoral calcium content was similar to that in calcium absorption. The calcium solubility in the ileum was increased in those rats fed on P-GGH. We conclude that cecal fermentation did not contribute to the increased calcium absorption by the rats fed on P-GGH.

An experience for ELISA for desmoglein 1, suggesting a possible diagnostic help to determine the initial therapy for pemphigus foliaceus

Pemphigus foliaceus (PF) is an autoimmune skin disease in which loss of adhesion between keratinocytes (i.e., acantholysis) in the granular cell layers appears to be mediated by the binding of autoantibodies against desmoglein (Dsg) 1. Although it has been suggested that the activity of the disease is rather correlated with the titer of the antibody, there are still no precise studies on the relationships between the disease activity and the titers of autoantibody against Dsg1 by using ELISA. In this study, we performed ELISA using recombinant Dsg1 (rDsg1) as antigen on 8 patients with pemphigus foliaceus in order to examine the reliability of this test for monitoring disease severity. The resultant index values of ELISA, which were defined by the formula: (OD of tested serum - OD of negative control)/(OD of positive control - OD of negative control) X 100, ranged from 16 to 264 compared with 6.41 of cutoff index value for normal sera. A patient with an index value of 213 had severe widespread erosions with erythema and required pulse therapy of methylpredonisolone (1,000 mg/day for 3 days). A patient with an index value of 111 had a moderate severity and was successfully treated with an initial dose of 30 mg/day (0.64 mg/kg) of predonisolone. The mildest patient with an index value of 16 was controlled with only topical application of 0.05% betamethasone ointment twice a day. These results suggest that ELISA index values for rDsg1 will provide a promising tool for monitoring the disease severity and for determining the initial therapy for pemphigus foliaceus.

Structure-activity relationships of a new antifungal imidazole, AFK-108, and related compounds

Fungicidal activity of widely used imidazole antifungal drugs in topical applications is not so strong in spite of their fungistatic activities against dermatophytes and pathogenic yeasts. In order to improve fungicidal activity of imidazole antifungal agents, a series of novel imidazole derivatives having a hydrophobic substituent derived from isoprenoid were synthesized. The efficacy of these compounds was evaluated with respect to direct cell-membrane damaging activity, ergosterol biosynthesis inhibition, minimum growth-inhibitory concentration (MIC) and therapeutic effect for experimental dermatophytosis of guinea pigs. Among the newly synthesized compounds, the geranyl derivative named AFK-108 (2a) showed the highest in vivo fungicidal activity with both cell membrane damaging activity and ergosterol biosynthesis inhibition in vitro.

Lipid alterations in the liver and serum of rats in histidine-excess and copper deficiency

To obtain further information on lipid metabolism in the histidine-excess and copper-deficiency, rats were fed basal, histidine-excess (the addition of 50 g L-histidine/kg diet) or copper-deficient diets for 0, 7, 21 and 42 d ad libitum. Liver triacylglycerol accumulated and the serum triacylglycerol level decreased after feeding of the histidine-excess diet for 21 or 42 d, but not after feeding of the copper-deficient diet. Serum cholesterol level increased in rats fed the histidine-excess diet for 7, 21 and 42 d, but not in rats fed the copper-deficient diet. Copper content in the liver and serum significantly decreased in rats fed the histidine-excess diet. Copper content in the liver and serum was markedly decreased in rats fed the copper-deficient diet. Liver zinc content was constant, but the serum zinc level decreased in rats fed the histidine-excess diet. Feeding of the copper-deficient diet hardly affected zinc content in the liver and serum. Urinary copper and zinc increased in rats fed the histidine-excess diet, and decreased or showed a decreasing tendency in rats fed the copper-deficient diet. Overall results indicated that feeding the histidine-excess diet caused copper deficiency, whereas hypercholesterolemia was not shown in rats fed the copper-deficient diet although the livers of rats fed the copper-deficient diet contained less copper than those of rats fed the histidine-excess diet. Thus, the responses on liver triacylglycerol and serum cholesterol to copper deficiency induced by the feeding of a histidine-excess diet are different from those to copper deficiency induced by feeding of a copper-deficient diet.

Purification and characterization of rat sterol 14-demethylase P450 (CYP51) expressed in Escherichia coli

Sterol 14-demethylase P450 (CYP51) is an essential enzyme for sterol biosynthesis by eukaryotes. We have cloned rat and human CYP51 cDNAs [Aoyama, Y., Noshiro, M., Gotoh, O., Imaoka, S., Funae, Y., Kurosawa, N., Horiuchi, T., and Yoshida, Y. (1996) J. Biochem. 119, 926-933]. The cloned rat CYP51 cDNA was expressed in Escherichia coli with modification of the N-terminal amino acid sequence, and the expressed protein (CYP51m) was purified to gel-electrophoretic homogenity. The spectrophotometrically determined specific content of CYP51m was 16 nmol/mg protein and the apparent molecular weight was estimated to be 53,000 on SDS-PAGE. Soret peaks of the oxidized and reduced CO-complex of CYP51m were observed at 417 and 447 nm, respectively. The purified CYP51m catalyzed the 14-demethylation of lanosterol and 24,25-dihydrolanosterol upon reconstitution with NADPH-P450 reductase purified from rat liver microsomes. The apparent K(m) and V(max) values for lanosterol were 10.5 microM and 13.9 nmol/min/nmol P450, respectively, and those for 24, 25-dihydrolanosterol were 20.0 microM and 20.0 nmol/min/nmol P450, respectively. The lanosterol demethylase activity of the reconstituted system of CYP51m was inhibited by ketoconazole, itraconazole and fluconazole with apparent IC(50) values of 0.2, 0.7, and 160 microM, respectively.

Effects of dietary protein type on the response of lipid metabolism to orotic acid in rats

The effects of orotic acid supplementation to casein, egg protein, soy protein and wheat gluten diets on the lipids of liver and serum were compared. When orotic acid was added, the contents of total lipids and triacylglycerol in the liver of the casein group were significantly higher or tended to be higher than those of the other three dietary groups. Dietary orotic acid had no effect on the food intake. The liver weight, and liver total lipids, triacylglycerol, cholesterol and phospholipids were increased or tended to be increased by the addition of orotic acid. The serum triacylglycerol level was decreased by the addition of orotic acid to either the casein or soy protein diet. Thus, the response to liver lipid accumulation induced by orotic acid feeding depended on the dietary protein type.

Transmembrane signaling for adhesive regulation of desmosomes and hemidesmosomes, and for cell-cell datachment induced by pemphigus IgG in cultured keratinocytes: involvement of protein kinase C

We have investigated transmembrane signaling for the regulation of desmosomes and hemidesmosomes, using a human squamous cell carcinoma cell line (DJM-1) and normal human keratinocytes. This review discusses the involvement of protein kinase C (PKC) in regulation of these junctions, and signaling pathways involved in cell-cell detachment induced by pemphigus vulgaris (PV) IgG in a culture system. Cells grown in low-Ca++ conditions, which lack desmosomes, rapidly form desmosomes upon a low-normal Ca++-shift in association with PKC-activation and, in turn, PKC-activation by 12-O-tetradecanoylphorbol-13-acetate (TPA) induces desmosome formation even in low-Ca++ conditions. TPA induces serine-phosphorylation of the 180 kDa-bullous pemphigoid antigen (BPAG2), generating 190 kDa-phosphorylated BPAG2, and dissociates BPAG2 from hemidesmosomes. TPA-treatment also causes secretion of urokinase-type plasminogen activator (uPA) and expression of its receptor (uPAR), which activates plasminogen to plasmin and may digest extracellular domains of desmosomes and hemidesmosomes. These results suggest that PKC may play a role in activation of desmosome turnover and dysfunction of hemidesmossomes, and thus a role in up-migration of keratinocytes. Binding of PV-IgG to Dsg3 induces activation of diverse isoenzymes of PKC, linked to uPA secretion and uPAR expression. Furthermore, PV-IgG binding alone induces the serine-phosphorylation of Dsg 3, associated with its dissociation from plakoglobin and its deletion from desmosomes. This PV-IgG-induced Dsg 3-phosphorylation and Dsg 3-deletion from desmosomes may impair desmosome formation, whereas PV-IgG-induced PKC signaling mediates the uPA secretion and uPAR expression leading to digestion of preexisting desmosomes from the outside of the cell. These two different PV-IgG-activated signaling pathways may play a key role in acantholysis in PV.

Stimulative effect of a casein hydrolysate on exocrine pancreatic secretion that is independent of luminal trypsin inhibitory activity in rats

We have previously demonstrated that proteins could stimulate pancreatic secretion independently of luminal bile-pancreatic juice (BPJ) in a BPJ-diverted rat. To determine whether luminal protease-independent pancreatic secretion occurs in normal rats with BPJ returned to the upper small intestine, we investigated the pancreatic secretory response to intraduodenal instillation of a casein hydrolysate or the synthetic trypsin inhibitor, FOY 305, at concentrations which could almost equally inhibit hydrolysis of the synthetic substrate for trypsin with the luminal content. FOY 305 at 10 micrograms/ml and casein hydrolysate solutions at both 100 and 200 mg/ml similarly inhibited approx. 80% of the tryptic activity in the luminal contents of the proximal small intestine. Intraduodenal administration of casein hydrolysate solutions (100 and 200 mg/ml) significantly increased pancreatic secretion in a dose-dependent manner. However, intraduodenal administration of FOY 305 (10 micrograms/ml) was ineffective for stimulating pancreatic secretion. These results demonstrate that dietary protein enhances pancreatic secretion independently of the masking of luminal trypsin activity in rats.

A pathogenic autoantibody, pemphigus vulgaris-IgG, induces phosphorylation of desmoglein 3, and its dissociation from plakoglobin in cultured keratinocytes

Pemphigus vulgaris (PV) is an autoimmune blistering skin disease, which is characterized by autoantibodies to a specific desmosomal constituent, i.e. desmoglein 3 (Dsg3). In this study, we analyzed phosphorylation of desmosomal proteins and their molecular interactions after PV-IgG binding to Dsg3 using DJM-1 cells, a squamous cell carcinoma cell line, and normal human keratinocytes. Cells were metabolically labeled with 32P inorganic phosphate, followed by stimulation with the IgG fractions from five PV patients or normal individuals for 20 min. Phosphorylation of specific desmosomal components and their molecular interactions were studied in immunoprecipitates using PV-IgG and anti-plakoglobin (PG) antibodies. PV-IgG binding alone induced the phosphorylation of Dsg3 at serine residues. Although Dsg3 and PG were coprecipitated by PV-IgG-immunoprecipitation when treated with normal IgG, PG was not coprecipitated with Dsg3 when stimulated with PV-IgG, suggesting that PV-IgG binding to Dsg3 caused the dissociation of Dsg3 from PG. These results demonstrate that the binding of pathogenic PV autoantibodies to the cell surface antigen Dsg3, which is an adhesion molecule categorized into desmosomal cadherins, caused particular phosphorylation of Dsg3 and its dissociation from PG.

Guanidinated casein hydrolysate stimulation of cholecystokinin release via pancreatic enzyme- and cholinergic-independent mechanisms in rats

We had demonstrated that a peptic hydrolysate of guanidinated casein that is made from casein by the conversion of lysine to homoarginine stimulated pancreatic exocrine secretion in rats with chronic bile-pancreatic juice (BPJ) diversion from the proximal small intestine. This modified protein also stimulated cholecystokinin (CCK) release from dispersed rat intestinal cells. In this study, we found that guanidinated casein hydrolysate stimulates CCK release in chronic BPJ-diverted rats with cholinergic control blocked by atropine. Intraduodenal guanidinated casein hydrolysate increased portal plasma CCK concentration and pancreatic secretion in atropine-treated BPJ-diverted rats. In contrast, the portal plasma CCK concentration was not increased by intact casein hydrolysate. We conclude that guanidinated casein hydrolysate directly stimulates CCK release from the intestine via some cholinergic-independent mechanism, and an increase of the pancreatic exocrine secretion is regulated by CCK released by guanidinated casein hydrolysate. A guanidyl residue is likely to be involved in this control.

Cholesterol synthesis and degradation in normal rats fed a cholesterol-free diet with excess cystine

Feeding a diet with excess cystine to rats resulted in hypercholesterolemia. To understand the mechanism of the hypercholesterolemia, cholesterol synthesis and degradation, bile acid content of bile, and fecal steroids were determined. The in vivo incorporation of tritiated water into hepatic cholesterol, and activity of hepatic 3-hydroxy-3-methylglutaryl-CoA reductase in rats fed a high-cystine diet were significantly higher than those in rats fed a control diet. The activity of hepatic cholesterol 7 alpha-hydroxylase was similar between two groups. Little effect of cystine supplementation was found on fecal sterol excretion although there were some changes in biliary excretion of cholic acid derivatives. These results indicate that hypercholesterolemia caused by feeding of a high-cystine diet may be due to the stimulation of hepatic cholesterol synthesis.

Ingestion of sugar beet fiber enhances irradiation-induced aberrant crypt foci in the rat colon under an apoptosis-suppressed condition

The induction of aberrant crypt foci (ACF) by irradiation of gamma-rays (60Co), and the effect of dietary sugar beet fiber (SBF) on irradiation-induced ACF were examined. We found that abdominal irradiation of gamma-rays could induce ACF in the rat colon. The irradiation was performed once a week at a dose rate of 2 or 3 Gy per irradiation. Irradiation-induced ACF were observed in the colon at 10 weeks after the first irradiation at dose of 2 Gy for six times or 3 Gy for four times. Dietary SBF had no effect on the number of ACF, aberrant crypts (AC) or AC/focus induced by abdominal gamma-irradiation. However, an ingestion of SBF resulted in an increase in the number of these parameters in apoptosis-suppressed rats by cycloheximide (CHX). An injection of CHX suppressed irradiation-induced apoptosis of the colonic epithelial cells for at least 6 h after the irradiation. In CHX-injected rats, an ingestion of SBF significantly increased the number of ACF, AC and AC/focus compared with fiber-free fed rats at 9 weeks after the first irradiation. On the other hand, in saline-injected rats, no significant difference was found between SBF and fiber-free diets in the number of ACF, AC and AC/focus through the experimental period. These results suggest that dietary SBF may be involved in the elimination of abnormal cells from an irradiated colon through the apoptosis of colonic epithelial cells. In this study, we have shown a new method for inducing ACF by using gamma-rays which were not influenced by luminal contents such as bacterial enzyme, at least in the initiation stage.

Short-chain fatty acids suppress cholesterol synthesis in rat liver and intestine

We previously showed that plasma cholesterol levels decreased following ingestion of a short-chain fatty acid (SCFA) mixture composed of sodium salts of acetic, propionic, and butyric acids simulating cecal fermentation products of sugar-beet fiber (SBF). In the present study, we investigated whether hepatic and small intestinal cholesterol synthesis is involved in the cholesterol-lowering effects of SCFA and SBF. In vitro (expt. 1) and in vivo (expt. 2) cholesterol synthesis rates and the diurnal pattern of SCFA concentrations in portal plasma (expt. 3) were studied in three separate experiments in rats fed diets containing the SCFA mixture, SBF (100 g/kg diet), or the fiber-free control diet. Cholesterol synthesis was measured using 3H2O as a tracer. The in vitro rate of cholesterol synthesis, measured using liver slices, was greater in the SBF group, but not in the SCFA group, than in the fiber-free control group. In contrast, the hepatic cholesterol synthesis rate in vivo was lower in the SCFA group, but not in the SBF group, than in the control group. The mucosal cholesterol synthesis rate for the whole small intestine was <50% of the hepatic rate. The rate in the proximal region was slightly but significantly lower in the SCFA group, and was significantly higher in the SBF group than in the fiber-free group. The rate in the distal small intestines was also significantly greater in the SBF group than in the fiber-free group. Plasma total cholesterol concentrations were lower in the SCFA and SBF groups than in the fiber-free group in both experiments 2 and 3. Diurnal changes in portal SCFA and cholesterol levels were studied in the experiment 3. SCFA concentrations increased rapidly after the start of feeding the SCFA diet, and changes in plasma cholesterol were the reciprocal of those observed in SCFA. These results show that a decrease in hepatic cholesterol synthesis rate mainly contributes to the lowering of plasma cholesterol in rats fed the SCFA mixture diet. Changes in portal SCFA and cholesterol concentrations support this conclusion. In SBF-fed rats, SCFA produced by cecal fermentation are possibly involved in lowering plasma cholesterol levels by negating the counteractive induction of hepatic cholesterol synthesis caused by an increase in bile acid excretion.

Ingestion of guar-gum hydrolysate partially restores calcium absorption in the large intestine lowered by suppression of gastric acid secretion in rats

We examined the effects of feeding guar-gum hydrolysate (GGH), a highly fermentable form of dietary fibre with low viscosity, on Ca absorption in the small and large intestines in rats under conditions in which gastric acid secretion was suppressed by a proton pump inhibitor, omeprazole. We also examined the role of the caecum in influencing these effects. The study was designed in a 2 x 2 x 2 factorial arrangement with two diet (GGH-containing (50 g/kg diet) and GGH-free diets) groups, two injection (omeprazole and vehicle) groups and two operation (sham and caecectomy) groups. Apparent Ca absorption was lower in rats administered omeprazole (30 mg/kg body weight per d) for 8 d than in rats administered the vehicle. Ingestion of GGH led to partial restoration of Ca absorption decreased by omeprazole treatment. However, this increment in Ca absorption was not sufficient to meet requirements because the dietary Ca level (3.0 g/kg diet) was the minimum requirement for the intact rats. The small increment in Ca absorption caused by the GGH diet was completely abolished by caecectomy. Soluble Ca pools in the caecal and colonic contents were increased by feeding GGH, and the soluble Ca concentrations were much higher than the Kt values of the Ca active transport system in the large intestine or the serum Ca concentration. These findings suggest that Ca solubilization is not a limiting factor for Ca absorption in the large intestine. Apparent Mg absorption was clearly lower in caecectomized rats than in sham-operated rats, and higher in the GGH-fed groups than in the groups fed on the GGH-free diet, even in the case of caecectomized rats. We conclude that Ca absorption lowered by inhibition of gastric acid secretion is partially restored in rats fed with GGH, but the increment is not sufficient to meet requirements.

Effects of pH on contraction and Ca2+ mobilization in vascular smooth muscles of the rabbit basilar artery

The present study was undertaken to investigate the effects of extracellular pH (pHe) and intracellular pH (pHi) on 5-hydroxytryptamine (5-HT)-induced contraction and Ca2+ mobilization in vascular smooth muscles. Strip preparations of the rabbit basilar artery without endothelium were loaded with 40 microM fura-2-AM and 2 microM BCECF-AM and mounted in an organ bath. The isometric tension was recorded by using a force displacement transducer. Administration of 5-HT caused dose-dependent contraction in the rabbit basilar arteries. Acidification of pHe from 7.40 to 6.90 reduced the 5-HT-induced contraction and [Ca2+]i transients. Alkalinization of pHe from 7.40 to 7.90, on the other hand, enhanced the contraction and elevation of [Ca2+]i. In the other series of experiments, pHi (7.12 in normal PSS) was selectively altered by adding either butyric acid or trimethylamine. Intracellular acidification (pHi = 6.89) and alkalinization (pHi = 7.35) without changes in pHe produced qualitatively similar effects to those caused by extracellular acidification and alkalinization, respectively. Ca-sensitivity, which is defined as Deltatension/Delta[Ca2+]i, was not affected by the alteration of pHe nor pHi. In the Ca2+-free solution, the addition of 5-HT produced transient increases in [Ca2+]i and isometric tension that were much smaller than those in the normal physiological salt solution. The 5-HT-induced responses of [Ca2+]i and tension in the Ca2+-free solution were not affected by acidification nor alkalinization. These results suggest that a 5-HT-induced contraction is significantly modulated by pH through changing the [Ca2+]i transients, and that the change of pHi plays, at least in part, a role in the alteration of 5-HT-induced contraction resulting from acidosis or alkalosis in the rabbit basilar artery.