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.

Pemphigus vulgaris-IgG causes a rapid depletion of desmoglein 3 (Dsg3) from the Triton X-100 soluble pools, leading to the formation of Dsg3-depleted desmosomes in a human squamous carcinoma cell line, DJM-1 cells

In this study, we examined desmoglein (Dsg) 3 and other desmosomal molecules after pemphigus vulgaris (PV)-immunoglobulin G (IgG) binding to the Dsg3 on the cell surface in DJM-1 cells, a human squamous cell carcinoma cell line. After cells were incubated with PV-IgG for various time periods (0, 5, 10, 20, 30, 60 min, or 30 h), cells were fractionated into phosphate-buffered saline soluble (cytosol), phosphate-buffered saline insoluble-Triton X-100 soluble (membrane), and Triton X-100 insoluble (cytoskeleton) fractions, and subjected to immunoblotting and immunofluorescence microscopy using antibodies against Dsgl, Dsg3, plakoglobin, desmoplakin 1, and cytokeratins. Immunoblot analysis with PV-IgG revealed that Dsg3 was already dramatically depleted from the membrane fraction 20 min after PV-IgG treatment, whereas no reduction of Dsg3 was detected in the cytoskeleton fraction as examined by immunoblotting. A 30 h incubation with PV-IgG, however, caused a marked disappearance of Dsg3, but not other desmosomal molecules, from cytoskeleton fractions. Furthermore, double-staining immunofluorescence microscopy revealed that Dsg3 was depleted from the desmosomes whereas Dsg1, desmoplakin 1, plakoglobin, and keratin filaments were bound to desmosomes. These results provide a novel interpretation for a better understanding of mechanisms for blistering in PV; i.e., a possibility that PV-IgG generates the formation of aberrant desmosomes, which are lacking in Dsg3, but not other desmosomal constituents.

Ingestion of guar gum hydrolysate, a soluble fiber, increases calcium absorption in totally gastrectomized rats

Gastrectomy induces osteopenia. We examined the effects of feeding a diet containing soluble dietary fiber, guar gum hydrolysate (GGH, 50 g/kg diet), on intestinal calcium absorption and bone mineralization in totally gastrectomized (Roux-en-Y esophagojejunostomy) rats by comparing them with those in two control groups (laparotomized and bypassed rats). In the bypassed rats, chyme bypassed the duodenum and upper jejunum without gastrectomy. In a second separate experiment, we compared calcium absorption and bone mineralization in the gastrectomized rats fed diets containing soluble and insoluble calcium salts and in bypassed rats fed insoluble calcium. In Experiment 1, apparent absorption of calcium supplied as a water-insoluble salt was more than 50% lower in gastrectomized rats than in the intact (laparotomized) or bypassed rats 3 wk after the start of feeding the test diets (P < 0.05). Calcium absorption was higher (P < 0.05) in gastrectomized rats fed the GGH diet than in those rats fed the GGH-free diet. In Experiment 2, absorption of soluble calcium in the gastrectomized rats did not differ from the absorption of calcium from calcium carbonate by bypassed rats. The soluble calcium pool in the cecal contents was significantly lower in gastrectomized rats (Experiment 1) than in intact or bypassed control rats, and was higher (P < 0.05) in the GGH-fed gastrectomized rats than in those fed the GGH-free diet. However, calcium absorption correlated most closely (r = 0.787, P < 0.01) with cecal propionic acid concentration. The femur calcium content was significantly lower in gastrectomized rats fed insoluble calcium than in bypassed rats fed the same diet, but was partially restored in the rats fed soluble calcium (Experiment 2). Bone calcium was not increased by feeding GGH in gastrectomized rats (Experiment 1). We conclude that the severely diminished calcium absorption following total gastrectomy is totally due to a decrease in calcium solubilization, and feeding GGH partially restores calcium absorption. The decrease in bone calcium that occurs as a result of gastrectomy is mainly due to diminished intestinal calcium absorption.

Natriuretic peptides in the lung modulated by pneumonectomy

BACKGROUND

Natriuretic peptides are vasodilator hormones involved in the regulation of blood pressure and volume homeostasis. However, the mechanism of these peptides after pneumonectomy remains obscure.

METHODS

We investigated changes in the pulmonary arterial pressure and the localization and changes in the atrial (A-type) natriuretic peptide (ANP) and the C-type natriuretic peptide (CNP) in the lung, using immunohistochemistry and radioimmunoassay (RIA) in anesthetized dogs. Furthermore, we examined guanosine 3', 5'-monophosphate (cGMP) levels in plasma and in the contralateral lung.

RESULTS

Pulmonary arterial pressure was significantly increased after pneumonectomy. The immunoreactivities of both ANP and CNP were detected in the endothelium of the pulmonary artery. In the contralateral lung, the concentrations of ANP and CNP were both significantly increased. In plasma, only ANP levels were significantly increased. In contrast, the plasma and lung cGMP levels were significantly reduced after pneumonectomy.

CONCLUSIONS

We postulate that the processes from secretion in the vascular endothelial cells to the action via ANP and CNP receptors are effected in the contralateral lung tissue at the acute stage of pneumonectomy.

A paired wedge filter system for compensation in dose differences

OBJECTIVE

In radiotherapy, it is important to conform the high dose volume to the planned target volume. A variable thickness paired wedge filter system was developed to compensate for dose inhomogeneity arising from field width segment variation in conformal irradiation.

MATERIALS AND METHODS

The present study used a 6 MV linear accelerator equipped with multileaf collimator leaves and a paired wedge compensating filter system. The dose variation due to field width was measured in each field segment width. The variation in attenuation of the compensators was measured as a function of filter position. As the field width increases, the relative absorbed dose also increases; this is the point of requiring compensation, so it can be in reverse proportion.

RESULTS

As the field width increases, the relative absorbed dose also increases; this is why compensation is required and thus it must be in reverse proportion. Attenuation of the absorbed dose by the paired filters was in proportion to the filter position. The filter position to compensate for the difference of absorbed doses was defined by the square root of the field width. For a field varying in width from 4 to 16 cm, the variation in the absorbed dose across the field was reduced from 12% to 2.7%.

CONCLUSION

This paired wedge filter system reduced absorbed dose variations across multileaf collimator shaped fields and can facilitate treatment planning in conformal therapy.

Baicalein, an alpha-glucosidase inhibitor from Scutellaria baicalensis

Methanol extracts of Scutellaria baicalensis, Rheum officinale, and Paeonia suffruticosa showed potent inhibitory activity against rat intestinal sucrase. The active principles were identified as baicalein from the first and methyl gallate from the last two plants. In addition to its activity against the rat enzyme, baicalein also inhibited human intestinal sucrase expressed in Caco-2 cells.