Influence of FOXP3 single-nucleotide polymorphism after allogeneic hematopoietic stem cell transplantation

The impact of FOXP3 single-nucleotide polymorphisms (SNP) on clinical outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains poorly understood. We investigated the relationship between a FOXP3 SNP (rs3761548) and clinical outcomes in 91 patients with hematological malignancies after allo-HSCT. Multivariate analysis showed that risk of severe chronic graft-versus-host disease (cGVHD) was significantly higher in patients with the FOXP3-3279C/A or FOXP3-3279A/A genotype than those with the FOXP3-3279C/C genotype [hazard ratio (HR), 2.69; 95% confidence interval (CI) 1.14-6.31; p = 0.023]. Therefore, FOXP3 at SNP rs3761548 can be a useful marker for predicting the occurrence of severe cGVHD.

[Acquired thrombotic thrombocytopenic purpura during durvalumab monotherapy for non-small cell lung cancer]

Immune checkpoint inhibitor (ICI)-induced thrombocytopenias are rare immune-related adverse events (irAE), but ICI-related thrombotic thrombocytopenic purpura (TTP) is extremely rare. A 79-year-old woman with non-small cell lung cancer received maintenance therapy with the anti-human PD-L1 monoclonal antibody durvalumab. Four weeks after the last infusion, she developed overt TTP. Remission was achieved by plasma exchange and prednisolone, and the patient has now been recurrence-free for over 12 months. To our knowledge, this is the first report of TTP occurring as an irAE of durvalumab.

[CD5- and CD10-positive MYC and BCL2 double-expressor diffuse large B-cell lymphoma with MYD88L265P mutation: a case report and literature review]

A 75-year-old man who had lymphadenopathy was admitted to our hospital. Histopathological examination of cervical lymph node biopsy specimens showed diffuse proliferation of lymphoma cells with large nuclei. In immunohistochemistry, the lymphoma cells were positive for CD5, CD10, CD20, BCL2, BCL6, and MYC. The patient was diagnosed with CD5- and CD10-positive diffuse large B-cell lymphoma (DLBCL). MYD88^L265P mutations have been detected in DLBCL. Partial response was achieved after six courses of R-THP-COP therapy. However, the patient died because of disease progression 18 months after the diagnosis. On autopsy, lymphoma cells were found in the lymph nodes throughout the body, central nervous system, adrenals, and skin. CD5- and CD10-positive DLBCL account for 0.5-1% of DLBCL cases and have a very poor disease prognosis. This is a rare case of CD5- and CD10-positive DLBCL with MYC and BCL2 expressions harboring MYD88^L265P mutation.

Increased MYC expression without MYC gene translocation in patients with the diffuse large B-cell-lymphoma subtype of iatrogenic immunodeficiency-associated lymphoproliferative disorders

Post-transplant lymphoproliferative disorder (PTLD) and other iatrogenic immunodeficiency-associated lymphoproliferative disorders (OIIA-LPD) are iatrogenic lymphoproliferative disorders (LPD) that develop in association with immunosuppressive treatment in the setting of organ transplantation and autoimmune disease, respectively. Each has a spectrum of pathologies ranging from lymphoid hyperplasia to lymphoma. To clarify the characteristics of the diffuse large B-cell lymphoma (DLBCL) subtype in a cohort of 25 patients with PTLD or OIIA-LPD from our institute, we selected 13 with a histological subtype of DLBCL, including 2 cases of PTLD and 11 of OIIA-LPD. The median patient age at diagnosis was 70 years, with a female predominance. Both PTLD cases developed after kidney transplant. Of the patients with OIIA-LPD, 10 had rheumatoid arthritis, 1 had mixed connective tissue disease, and 8 were treated using methotrexate. Both of the PTLD patients and 6 of the OIIA-LPD patients had extranodal manifestations. All patients except for one were classified as having the non-germinal center B-cell (non-GCB) subtype according to the Hans algorithm. Tissue samples from 8 patients were positive for CD30 and 8 were positive for Epstein–Barr virus (EBV)-encoded small RNA. Seven patients had MYC-positive tissue samples, but none had MYC translocation. Our study suggests that extranodal manifestations and the non-GCB subtype are common, that EBV is associated with the DLBCL subtype of PTLD and OIIA-LPD, and that anti-CD30 therapy is applicable. In addition, our patients with the DLBCL subtype of PTLD and OIIA-LPD exhibited MYC overexpression without MYC translocation, suggesting an alternative mechanism of MYC upregulation.

Characteristics and predictors of post-transplant-associated hemophagocytic lymphohistiocytosis in adults

Hemophagocytic lymphohistiocytosis (HLH) is an uncontrolled hyperinflammatory disorder driven by an overactive immune system that results in high mortality. Post-transplant-associated hemophagocytic lymphohistiocytosis (PT-HLH) is a type of secondary HLH that occurs following allogeneic hematopoietic stem cell transplantation (allo-HSCT). The clinical features of PT-HLH remain unclear and diagnostic and prognostic tools have not yet been established. Here, we retrospectively evaluated the clinical manifestations and outcomes of PT-HLH in 94 patients who underwent allo-HSCT. According to our PT-HLH criteria (hyperferritinemia and increased macrophage count in bone marrow), PT-HLH occurred in 12 patients (12.8%). The PT-HLH patients showed splenomegaly (P = .001), a higher risk of engraftment failure (P = .013), and an increased percentage of macrophages and hemophagocytes in bone marrow aspirates (P = .0009 and P = .0006, respectively). Moreover, univariate and multivariate analyses revealed that the survival rate was lower in PT-HLH patients than non-PT-HLH patients (P = .0017 and P = .034, respectively). This study defines the clinical features of PT-HLH and PT-HLH criteria that could be useful tools for diagnosing PT-HLH.

Elevated C-reactive protein level is associated with poor prognosis in follicular lymphoma patients undergoing rituximab-containing chemotherapy

Although follicular lymphoma (FL) is a pathological entity characterized by relatively uniform histological and molecular findings, its clinical course is highly variable. Establishment of therapeutic strategies based on a simple and practical prognostic model is important. C-reactive protein (CRP) is an adverse prognostic marker for various tumors and aggressive lymphomas. However, the significance of serum CRP levels as a prognostic index in low-grade lymphomas, such as FL, has not been thoroughly investigated. We retrospectively analyzed the relationship between serum CRP levels at diagnosis and the prognosis in patients with FL (n = 61) undergoing rituximab-containing chemotherapy. Elevated CRP levels showed a significant association with elevated fibrinogen (P = 0.002) in univariate analysis. Patients with higher CRP levels (> 5 mg/L) had a significantly shorter progression-free survival in multivariate analysis (P = 0.044). We concluded that serum CRP levels are important in prognostic stratification of patients with FL.

Refined Disease Risk Index for Hematological Malignancies, Including Rare Disorders, After Allogeneic Stem Cell Transplantation

OBJECTIVE

The refined disease risk index (R-DRI) is a well-designed prognostic parameter that is based on only the disease type and status and is used for stratifying patients undergoing allogeneic hematopoietic stem cell transplantation (allo HSCT) into 4 risk groups. However, the application of the R-DRI for rare diseases has remained unclear.

METHODS

We evaluated 135 patients who underwent allo HSCT for hematological malignancies including rare diseases, such as acute leukemia of ambiguous lineage, acute T-cell leukemia/lymphoma, extranodal natural killer T-cell lymphoma, and lymphoblastic lymphoma, at our institute.

RESULTS

According to the R-DRI, overall survival (OS) and progression-free survival at 2 years for patients with the low, intermediate, high, and very high groups were 66.7% and 66.7%, 60.8% and 56.0%, 27.1% and 23.7%, and 5.9% and 5.1%, respectively (P < .0001 and P < .0001, respectively). OS showed no significant difference between B-cell non-Hodgkin lymphoma (B-NHL) and T-cell non-Hodgkin lymphoma (T-NHL) (P = .71). Moreover, OS at 1 year was 80%, 14.3%, 60%, and 0% for the intermediate risk group, the very high-risk group of B-NHL, the intermediate risk group, and the high-risk group of T-NHL, respectively (P = .035).

CONCLUSION

We showed the applicability of the R-DRI for hematological malignancies, including rare disorders. However, we suggest that T-NHL patients may be better to be assigned between the nodal group and the extranodal group in the R-DRI.

Comparative Study of Tacrolimus and Short-Term Methotrexate: 2-Day versus 3-Day Methotrexate as Graft-versus-Host-Disease Prophylaxis after Umbilical Cord Blood Transplantation in Adults

Methotrexate (MTX) in combination with a calcineurin inhibitor has been commonly used for prophylaxis of graft-versus-host disease (GVHD) following umbilical cord blood transplantation (UCBT) in Japan. However, the appropriate prophylactic MTX dosage in UCBT has not been established to date. To determine the preferential GVHD prophylaxis in UCBT, this study retrospectively investigated the administration of short-term MTX for 2 days versus 3 days. Of 103 adult patients submitted to UCBT enrolled in the study, 73 received tacrolimus (TAC) with 2 days of MTX given at 10 mg/m² on day 1 and 7 mg/m² on day 3 (very short-term [vs] MTX), whereas 30 patients received TAC with 3 days of MTX given at 10 mg/m² on day 1, 7 mg/m² on day 3, and 7 mg/m² on day 6 (short-term [s] MTX). In univariate analysis, neutrophil engraftment was shown to be significantly better (P = .039) in the vsMTX/TAC group. Among high-risk patients, the vsMTX/TAC group also exhibited earlier neutrophil engraftment (P = .042); however, the incidence of acute GVHD was higher in the vsMTX/TAC group (P = .035) on univariate analysis. In multivariate analysis, compared with sMTX/TAC, vsMTX/TAC was associated with lower risk of relapse (hazard ratio, .27; 95% confidence interval, .11 to .64; P = .003) . These results suggest that vsMTX/TAC can be appropriate GVHD prophylaxis after UCBT, especially in higher-risk patients.

Impact of CD123 expression, analyzed by immunohistochemistry, on clinical outcomes in patients with acute myeloid leukemia

Aberrant expression of the interleukin-3 receptor alpha chain (IL3RA or CD123) is frequently observed in patients with a subset of leukemic disorders, including acute myeloid leukemia (AML), particularly in leukemia stem cells. We analyzed the relationships between immunohistochemical (IHC) expression, including that of CD123, and clinical outcomes. This study involved a retrospective analysis of 48 patients diagnosed with de novo AML (M0-M5, n = 48) at our hospital between February 2008 and September 2015. Among patients with de novo AML, CD123 expression was associated with a failure to achieve complete response (CR) to initial induction chemotherapy (P = 0.044) and poor overall survival (OS) (P = 0.036). This is the first study using IHC to demonstrate that CD123 expression is associated with a poor CR rate and poor OS in de novo AML patients. These results support previous reports using flow cytometry (FCM). CD123 expression may thus be useful for assessing AML patients' prognoses. At the time of diagnosis, CD123 expression analysis using IHC may represent a clinically useful assessment for de novo AML patients.

Monitoring TIGIT/DNAM-1 and PVR/PVRL2 Immune Checkpoint Expression Levels in Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia

After allogeneic stem cell transplantation (alloSCT), several immune checkpoints play an important role in the antileukemic immune response in the bone marrow (BM) microenvironment. However, immune checkpoint expression levels in the BM have not been reported after alloSCT in patients with acute myeloid leukemia (AML). We investigated the clinical impact of immune checkpoint expression in BM samples after alloSCT for AML. Higher expression of T cell immunoreceptor with Ig and ITIM domains (TIGIT) was associated with a decreased incidence of acute graft-versus-host disease (P = .048) and poor overall (P = .046) and progression-free survival (P = 0.024). In addition, higher expression of TIGIT at engraftment after alloSCT was correlated with a decreased number of natural killer cells in BM (P = .019). Monitoring TIGIT expression in the BM could be useful for predicting outcome after alloSCT for AML. Our findings raise the possibility that blockade of TIGIT would improve survival.

Association of Soluble Interleukin-2 Receptor and C-Reactive Protein with the Efficacy of Bendamustine Salvage Treatment for Indolent Lymphomas and Mantle Cell Lymphoma

Bendamustine has demonstrated favourable efficacy in relapsed or refractory indolent lymphoma and mantle cell lymphoma. We retrospectively evaluated the pre-treatment clinical and laboratory factors and their correlation with the clinical outcome of these lymphomas. We analysed 53 patients who had been treated with bendamustine alone (n = 6) or rituximab plus bendamustine (n = 47). The overall response rate was 81.1%, with a complete response (CR) rate of 39.6%. The CR rate was significantly low in patients who had elevated levels of soluble interleukin-2 receptor (p = 0.024) and C-reactive protein (CRP; p = 0.004). The 1-year overall survival (OS) rate was 79.3%. An elevated CRP was associated with a short OS (p = 0.056). The present findings suggest that the lymphoma microenvironment and immune response were involved in the effects of bendamustine. These findings are also important in order to understand the pathophysiology of refractory lymphoma and to find effective strategies using bendamustine.

The prognostic value of the serum level of C-reactive protein for the survival of patients with a primary sarcoma of bone

The aim of this study was to determine whether the level of circulating C-reactive protein (CRP) before treatment predicted overall disease-specific survival and local tumour control in patients with a sarcoma of bone. We retrospectively reviewed 318 patients who presented with a primary sarcoma of bone between 2003 and 2010. Those who presented with metastases and/or local recurrence were excluded. Elevated CRP levels were seen in 84 patients before treatment; these patients had a poorer disease-specific survival (57% at five years) than patients with a normal CRP (79% at five years) (p < 0.0001). They were also less likely to be free of recurrence (71% at five years) than patients with a normal CRP (79% at five years) (p = 0.04). Multivariate analysis showed the pre-operative CRP level to be an independent predictor of survival and local control. Patients with a Ewing's sarcoma or chondrosarcoma who had an elevated CRP before their treatment started had a significantly poorer disease-specific survival than patients with a normal CRP (p = 0.02 and p < 0.0001, respectively). Patients with a conventional osteosarcoma and a raised CRP were at an increased risk of poorer local control. We recommend that CRP levels are measured routinely in patients with a suspected sarcoma of bone as a further prognostic indicator of survival.

Does the addition of cement improve the rate of local recurrence after curettage of giant cell tumours in bone?

We retrospectively compared the outcome after the treatment of giant cell tumours of bone either with curettage alone or with adjuvant cementation. Between 1975 and 2008, 330 patients with a giant cell tumour were treated primarily by intralesional curettage, with 84 (25%) receiving adjuvant bone cement in the cavity. The local recurrence rate for curettage alone was 29.7% (73 of 246) compared with 14.3% (12 of 84) for curettage and cementation (p = 0.001). On multivariate analysis both the stage of disease and use of cement were independent significant factors associated with local recurrence. The use of cement was associated with a higher risk of the subsequent need for joint replacement. In patients without local recurrence, 18.1% (13 of 72) of those with cement needed a subsequent joint replacement compared to 2.3% (4 of 173) of those without cement (p = 0.001). In patients who developed local recurrence, 75.0% (9 of 12) of those with previous cementation required a joint replacement, compared with 45.2% (33 of 73) of those without cement (p = 0.044).

FGF-2 stimulates periodontal regeneration: results of a multi-center randomized clinical trial

The efficacy of the local application of recombinant human fibroblast growth factor-2 (FGF-2) in periodontal regeneration has been investigated. In this study, a randomized, double-blind, placebo-controlled clinical trial was conducted in 253 adult patients with periodontitis. Modified Widman periodontal surgery was performed, during which 200 µL of the investigational formulation containing 0% (vehicle alone), 0.2%, 0.3%, or 0.4% FGF-2 was administered to 2- or 3-walled vertical bone defects. Each dose of FGF-2 showed significant superiority over vehicle alone (p < 0.01) for the percentage of bone fill at 36 wks after administration, and the percentage peaked in the 0.3% FGF-2 group. No significant differences among groups were observed in clinical attachment regained, scoring approximately 2 mm. No clinical safety problems, including an abnormal increase in alveolar bone or ankylosis, were identified. These results strongly suggest that topical application of FGF-2 can be efficacious in the regeneration of human periodontal tissue that has been destroyed by periodontitis.

Increased resistance of mice to Salmonella enterica serovar Typhimurium infection by synbiotic administration of Bifidobacteria and transgalactosylated oligosaccharides

AIMS

The anti-infectious activity of Bifidobacteria in combination with transgalactosylated oligosaccharides (TOS) against Salmonella enterica serovar Typhimurium LT-2 in an opportunistic antibiotic-induced murine infection model in mice was examined.

METHODS AND RESULTS

B. breve (strain Yakult) with natural resistance to streptomycin sulphate (SM, MIC: > 4 mg ml(-1)), when given daily at a dose of 108 cfu/mouse orally under SM treatment was constantly excreted at 10(10) cfu g(-1) faeces so long as SM was administered, even at 2 weeks after discontinuing administration of B. breve. Explosive intestinal growth and subsequent extra-intestinal translocation of orally infected LT-2 under SM treatment were inhibited by B. breve colonization, and this anti-infectious activity was strengthened by synbiotic administration of TOS with B. breve. Comparison of anti-Salmonella activity among several Bifidobacterium strains with natural resistance to SM revealed that strains such as B. bifidum ATCC 15696 and B. catenulatum ATCC 27539T conferred no activity, even when they reached high population levels similar those of effective strains such as strain Yakult and B. pseudocatenulatum DSM 20439. Both the increase in the concentration of organic acids and the lowered pH in the intestine due to bifidobacterial colonization correlated with the anti-infectious activity. Moreover, the crude cecal extract of B. breve-colonized mice exerted growth-inhibitory activity against LT-2 in vitro, whereas that of the ineffective B. bifidum-colonized cecum showed much lower activity.

CONCLUSIONS

Intestinal colonization by bifidobacteria given exogenously together with TOS during antibiotic treatment prevents the antibiotic-induced disruption of colonization resistance to oral infection with S. enterica serovar Typhimurium, and the metabolic activity needed to produce organic acids and lower the intestinal pH is important in the anti-infectious activity of synbiotics against enteric infection with Salmonella.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results indicate that certain bifidobacteria together with prebiotics may be used for the prophylaxis against opportunistic intestinal infections with antibiotic-resistant pathogens.

Antimicrobial activity of intraurethrally administered probiotic Lactobacillus casei in a murine model of Escherichia coli urinary tract infection

The antimicrobial activity of the intraurethrally administered probiotic Lactobacillus casei strain Shirota against Escherichia coli in a murine urinary tract infection (UTI) model was examined. UTI was induced by intraurethral administration of Escherichia coli strain HU-1 (a clinical isolate from a UTI patient, positive for type 1 and P fimbriae), at a dose of 1 x 10(6) to 2 x 10(6) CFU in 20 microl of saline, into a C3H/HeN mouse bladder which had been traumatized with 0.1 N HCl followed immediately by neutralization with 0.1 N NaOH 24 h before the challenge infection. Chronic infection with the pathogen at 10(6) CFU in the urinary tract (bladder and kidneys) was maintained for more than 3 weeks after the challenge, and the number of polymorphonuclear leukocytes and myeloperoxidase activity in the urine were markedly elevated during the infection period. A single administration of L. casei Shirota at a dose of 10(8) CFU 24 h before the challenge infection dramatically inhibited E. coli growth and inflammatory responses in the urinary tract. Multiple daily treatments with L. casei Shirota during the postinfection period also showed antimicrobial activity in this UTI model. A heat-killed preparation of L. casei Shirota exerted significant antimicrobial effects not only with a single pretreatment (100 microg/mouse) but also with multiple daily treatments during the postinfection period. The other Lactobacillus strains tested, i.e., L. fermentum ATCC 14931(T), L. jensenii ATCC 25258(T), L. plantarum ATCC 14917(T), and L. reuteri JCM 1112(T), had no significant antimicrobial activity. Taken together, these results suggest that the probiotic L. casei strain Shirota is a potent therapeutic agent for UTI.

Role of activity of gastrointestinal microflora in absorption of calcium and magnesium in rats fed beta1-4 linked galactooligosaccharides

Rats fed a diet containing beta1-4 linked galactooligosaccharides (GOS) (5 g/100 g of diet) absorbed calcium and magnesium more efficiently than those fed the control diet. However, the increment obtained through GOS-feeding was reduced by neomycin sulfate (0.67 g/100 g of diet). Since the decrease in cecal pH in rats fed GOS was suppressed by neomycin-feeding, bacterial action in the digestive tract was considered to be reduced by neomycin-feeding. Our findings suggest that the action of intestinal bacteria is necessary for the effects of GOS.

Protective effect of Lactobacillus casei strain Shirota on Shiga toxin-producing Escherichia coli O157:H7 infection in infant rabbits

We examined colonization patterns of Shiga toxin-producing Escherichia coli (STEC), concentrations of Shiga toxins (Stxs) and specific immunoglobulin A (lgA) against Stxs and STEC bacterial cell surface antigen in various portions of the gastrointestinal tract in an infant rabbit infection model. After inoculation of 3-day-old infant rabbits with STEC strain 89020087 at low doses (approximately 10(3) CFU/body), numbers of colonizing STEC bacteria and concentrations of Stxs in the intestine increased dramatically and the animals developed diarrhea within a couple of days after infection. Daily administration of Lactobacillus casei from the day of birth dramatically decreased the severity of diarrhea and lowered STEC colonization levels in the gastrointestinal tract 100-fold day 7 after infection. Both Stx1 and Stx2 concentrations in the intestines and histological damage to the intestinal mucus induced by STEC infection were decreased by the administration of L. casei. Examination of the concentrations of volatile fatty acids and pH of the intestinal contents revealed that the protective effect of L. casei administration against STEC infection was not due to fermented products such as lactic acid in the gastrointestinal tract. Administration of L. casei increased levels of lgAs against Stx1, Stx2, and formalin-killed STEC cells in the colon approximately two-, four-, and threefold, respectively, compared with those of the untreated controls by day 7 after infection. These results suggest that administration of L. casei strain Shirota enhances the local immune responses to STEC cells and Stxs and leads to elimination of STEC and thus decreases Stx concentrations in the intestines.

Effect of Angiotensin-Converting Enzyme Inhibition on Sympathetic Tone in Patients With Mild to Moderate Heart Failure

Sixteen patients with mild to moderate heart failure were examined to investigate whether sympathetic deactivation plays a role in the improvement in the failing heart by chronic angiotensin converting enzyme (ACE) inhibition. Measurements, including echocardiography, blood examinations, neurohumoral samplings (atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), norepinephrine), and spectral heart rate variability analysis by Holter electrocardiography, were carried out before and 6 months after the administration of lisinopril (5-10 mg/day). Quality of life assessment was accomplished by the Specific Activity Scale (SAS) questionnaire. Treatment with lisinopril for 6 months resulted in a significant reduction in systolic blood pressure. The left ventricular diastolic dimension significantly decreased and fractional shortening significantly increased on echocardiography. Of the 16 patients, 8 had improvement in their symptoms as measured by the SAS. Lisinopril did not significantly reduce the plasma norepinephrine concentration, but there was a significant reduction in the plasma ANP and BNP concentrations. In the heart rate power spectral analysis, total spectral power, high-frequency components and low/high frequency ratios did not change significantly with lisinopril. The mechanism by which ACE inhibitors improve mild to moderate heart failure is not by suppressing sympathetic activity.

Lower plasma triglyceride level in Syrian hamsters fed on skim milk fermented with Lactobacillus casei strain Shirota

The effect of fermented skim milk (FSM) by Lactobacillus casei strain Shirota on plasma lipids in hamsters was examined. Hamsters fed on cholesterol-free and -enriched diets containing 30% FSM had lower levels of plasma triglyceride than those fed on the control diet. In the experiment with the cholesterol-enriched diet-fed hamsters, the plasma triglyceride level was suppressed by FSM at concentrations of 10% to 30%. Unfermented milk tended to lower the level of triglyceride, but not significantly. The plasma cholesterol concentration was not affected by an FSM and unfermented skim milk supplement to the diet. L. casei strain Shirota grew well in the presence of mixed lipid micelles containing bile acid, but did not have the ability to remove cholesterol from the culture broth. These results indicate that FSM lowered the plasma triglyceride level in hamsters.

Blockade of cardiac ATP-sensitive K+ channel by cibenzoline targets its pore-forming subunit

Several antiarrhythmic agents with Na-channel blocking action have been shown to inhibit cardiac K(ATP) channels. We used cibenzoline to examine its precise target site using patch-clamp techniques and receptor binding assays in guinea-pig ventricular myocytes. Exposure of myocytes to a glucose-free perfusate containing 1 mM cyanide produced a time-dependent shortening of the action potential duration (APD) in the current-clamp mode. Cibenzoline (30 microM) slowed the development of APD shortening (APD90 to approximately 91% vs. approximately 55% control 16 min after metabolic inhibition) at pHo 7.4, but not at pHo 6.4 (to approximately 60%). The pinacidil (30 microM)-induced K(ATP) currents were inhibited by cibenzoline in a pHo-dependent manner: the higher the pHo, the stronger the blocking effect of cibenzoline. The binding of [3H]-labeled cibenzoline was prevented by cibenzoline, but not by glibenclamide. Alkalinization produces a higher concentration of the uncharged form of cibenzoline, which can more easily permeate the cell membrane than the charged form. In NIH3T3 cells stably expressing Kir6.1, a putative pore-forming subunit of K(ATP) channel, cibenzoline but not glibenclamide inhibited the K conductance. Thus cibenzoline interacts with the channel pore-forming subunit of the K(ATP) channel (Kir6.2), but not the sulfonylurea receptor, from the cytosolic side after it permeates into the cell interior via the membrane lipid bilayer.

Effect of L-lactic acid on the absorption of calcium in gastrectomized rats

The effect of dietary L-lactic acid (LA), (0.5, 1.0, or 2.5 g/100 g of diet) on the absorption of calcium in gastrectomized rats was evaluated for 28 d. Calcium phosphate was used as a source of calcium. The apparent calcium absorption ratio and the calcium contents of the femur and tibia in gastrectomized rats fed the control diet were significantly less than those in sham-operated rats. In the gastrectomized rats, the apparent calcium absorption ratio and the calcium contents of bone in the rats fed the lower doses of LA diets (LA 0.5 or 1.0 g/100 g of diet) were not affected; however, the apparent calcium absorption ratio and the calcium contents of bone in the rats fed the highest doses of LA diet (LA 2.5 g/100 g of diet) were greater than those in gastrectomized rats fed the control diet. Dietary LA (2.5 g/100 g of diet) also enhanced the phosphorus absorption and bone phosphorus content in the gastrectomized rats. We speculated that the highest dose of dietary LA might be associated with the dissolving of a water-insoluble form of calcium salt in the diet, thereby facilitating the calcium absorption and resulting in increased bone calcium content in gastrectomized rats.

Successful radiofrequency current catheter ablation of accessory atrioventricular pathway after tricuspid replacement in Ebstein's anomaly

A 15-year-old female with Ebstein's anomaly was referred to hospital for radiofrequency (RF) current catheter ablation of her refractory paroxysmal supraventricular tachycardia (PSVT) after tricuspid valve replacement. A surface ECG showed ventricular preexcitation of type B Wolff-Parkinson-White (WPW) syndrome. In a baseline electrophysiological study, two types of PSVT with left and right bundle branch block (LBBB and RBBB) configurations were induced. The LBBB type was antidromic and the RBBB type was orthodromic atrioventricular reciprocating tachycardia (AVRT) with a right posterolateral accessory pathway. RF current was successfully delivered at the posterolateral site above the prosthetic valve (V-delta interval = -30 msec). The patient has been free from arrhythmias during a follow-up period of 9 months. RF current ablation seems to be useful for AVRT patients with corrected Ebstein's anomaly.

Effect of L-lactic acid on calcium absorption in rats fed omeprazole

We examined the effect of L-lactic acid on calcium absorption in male Wistar rats made achlorhydric by dietary omeprazole, a proton pump inhibitor. The dietary omeprazole intake (0.03 g/100 g of diet) increased the gastric pH and decreased the apparent calcium absorption ratio. Dietary famotidine (0.03 g/100 g of diet), an H2-receptor antagonist, and lower doses of omeprazole (0.005 or 0.01 g/100 g of diet) did not affect the gastric pH or the calcium absorption. In a second experiment, dietary lactic acid (0.5, 1.0, or 2.5 g/100 g of diet) increased the intestinal calcium absorption dose dependently in rats fed omeprazole (0.03 g/100 g of diet). The gastric pH was significantly decreased only in the rats fed higher doses of lactic acid (1.0, or 2.5 g/100 g of diet). In a third experiment, a dietary sour milk beverage containing lactic acid (0.5 g/100 g of diet) increased the intestinal calcium absorption, but did not affect the gastric pH in rats fed omeprazole (0.03 g/100 g of diet). Although the significance of gastric acid in terms of overall calcium absorption is not known, under the present experimental conditions, the inhibition of gastric acid secretion by dietary omeprazole decreased the apparent calcium absorption, and the dietary lactic acid prevented the calcium absorption in rats fed omeprazole.

Functional compartmentalization of ATP is involved in angiotensin II-mediated closure of cardiac ATP-sensitive K+ channels

BACKGROUND

The effects of angiotensin II (Ang II) on ATP-sensitive K+ channels (K(ATP)) were investigated in ventricular myocytes enzymatically isolated from adult guinea pig heart.

METHODS AND RESULTS

In the whole-cell and cell-attached configurations (including open-cell-attached mode) of the patch-clamp technique, K(ATP) currents (I(KATP)) were activated through metabolic poisoning by the use of inhibitors of both glycolytic and oxidative ATP productions at 37 degrees C. In the whole-cell mode, I(KATP) were reversibly suppressed by increasing extracellular glucose and Ang II (1 nmol/L). In the cell-attached mode, Ang II concentration-dependently inhibited single K(ATP) activities with an IC50 value of 3.2+/-0.5 pmol/L (Hill coefficient=1.3+/-0.3). CV11974 (100 nmol/L), an angiotensin 1 (AT1) receptor-selective antagonist, blocked the inhibitory action of Ang II. Preincubation of myocytes with pertussis toxin (5 microg/mL for > 120 min at 37 degrees C) virtually prevented subsequent Ang II action. The inhibitory effect of Ang II was also abolished in the open-cell-attached mode (achieved by a prior perfusion of streptolysin-O, 0.08 U/mL). In this mode, through tiny membrane holes, the intracellular ATP concentration can be controlled by bathing extracellular solutions containing a known ATP concentration.

CONCLUSIONS

The inhibitory actions of Ang II on K(ATP) appear to be mediated by an increase in the subsarcolemmal ATP concentration that results from the inhibition of adenylate cyclase activities via AT1 receptors/PTX-sensitive G proteins.

Endothelin-1 inhibits the slow component of cardiac delayed rectifier K+ currents via a pertussis toxin-sensitive mechanism

Endothelin-1 (ET-1) is a 21-amino acid peptide hormone released from myocardial and endothelial cells, whose receptors (both ETA and ETB are expressed in the myocardium. We report here that ET-1 inhibits the cardiac delayed rectifier K+ current (IK) via a pertussis toxin (PTX)-sensitive mechanism. Ventricular myocytes enzymatically isolated from guinea pig hearts were voltage-clamped by the conventional whole-cell and nystatin-perforated patch technique (intrapipette and extrapipette K+ concentrations, 150 and 5.4 mmol/L, respectively) in the presence of nifedipine (2 mumol/L). Amplitudes of tail and steady state (2-second pulse) currents were measured as IK. ET-1 suppressed the basal IK by 20.9 +/- 2.3% in a concentration-dependent manner, with an IC50 of 1.1 +/- 0.3 nmol/L (n = 19), although it did not suppress the basal IK using the nystatin method. E-4031 (5 mumol/L), a blocker of the rapid component of IK (IKr), did not prevent the inhibitory action of ET-1. ET-1 reduced by 63.4 +/- 6.5% the slow component of IK (IKs) that had been enhanced to approximately 2-fold by isoproterenol (ISO, 20 nmol/L). The action was concentration dependent, with an IC50 of 0.7 +/- 0.4 nmol/L (n = 22), and was also observed using the nystatin method. The effect of ET-1 appeared to be mediated by an ETA receptor, because it was prevented by FR139317, an ETA-selective antagonist (1 mumol/L, n = 4), and sarafotoxin s6c, an ETB-selective agonist (100 nmol/L, n = 4), could not inhibit the ISO-enhanced IK. ET-1 antagonized IKs enhanced by histamine (250 nmol/L, n = 7) and forskolin (500 nmol/L, n = 7) but did not inhibit IKs enhanced by the internal application of cAMP (100 mumol/L, n = 6). Preincubation of myocytes with PTX (5 micrograms/mL for > 60 minutes at 36 degrees C) completely abolished the inhibitory action of ET-1 on the ISO-enhanced IKs (n = 4). Thus, nanomolar ET-1 inhibits IKs via the ETA receptor/PTX-sensitive G protein/PKA pathway.

Adaptation of rate of organic acid production of hindgut bacteria to chronic intake of galactooligosaccharide in the rat

We studied the adaptational effect of galactooligosaccharide (GOS) on the concentration of organic acids in cecal content, fecal water content and organic acid production from GOS in cultures with the cecal inocula of rats fed GOS for 1, 2, 7 or 21 d. The fecal water content of rats fed GOS for 1 d was higher than that of the controls. The concentration of each organic acid in the cecal contents was affected by diet, not by the time of adaptation. In in vitro fermentation, lactic acid was produced by rapidly and remained in the cultures with homogenates of rats fed GOS for 1 d. Acetic acid in the cultures of the GOS-diet rats' cecal homogenates was produced more rapidly than that of the controls on days 2, 7 and 21 of adaptation. Propionic acid was produced more rapidly in the GOS homogenate cultures than in that of the controls on day 2. Butyric acid in the cultures from the GOS-fed rats was produced more rapidly than that of the controls on days 2 and 21. These results suggest that the time period of GOS feeding influenced the production rate of each organic acid, and the changes varied among acids.

Exercise-induced second-degree atrioventricular block

In this report we describe 2 patients with exercise-induced, second-degree atrioventricular (AV) block. Case 1 was a 49-year-old man with normal AV conduction at rest but who developed dyspnea on exertion. Treadmill testing showed an exercise-induced 2:1 AV block. Electrophysiologic study (EPS) demonstrated rate-dependent, presumably intrahissian, AV block. Case 2 was a 31-year-old woman with first-degree AV block and complete right bundle branch block with dyspnea on exertion and occasional syncope. She had twice undergone surgical patch closure of an ostium primum atrial septal defect. Exercise testing induced type II second-degree AV block. Atrial pacing during EPS did not disclose rate-dependent type II AV block, but disopyramide induced second-degree AV block.

The effect of calcium gluconate and other calcium supplements as a dietary calcium source on magnesium absorption in rats

The effects of commercially available calcium supplements (calcium carbonate, calcium gluconate, oyster shell preparation and bovine bone preparation) and gluconic acid on the absorption of calcium and magnesium were evaluated for 30 days in male Wistar rats. There were no differences in the apparent absorption ratio of calcium among rats fed each calcium supplement; however, the rats fed the calcium gluconate diet had a higher apparent absorption ratio of magnesium than the rats fed the other calcium supplements. Dietary gluconic acid also more markedly stimulated magnesium absorption than the calcium carbonate diet, and the bone (femur and tibia) magnesium contents of rats fed the gluconic acid diet were significantly higher than those of the rats fed the calcium carbonate diet. Furthermore, the weight of cecal tissue and the concentrations of acetic acid and butyric acid in cecal digesta of rats fed the calcium gluconate diet or the gluconic acid diet were significantly increased. We speculate that the stimulation of magnesium absorption in rats fed the calcium gluconate diet is a result of the gluconic acid component and the effect of gluconic acid on magnesium absorption probably results from cecal hypertrophy, magnesium solubility in the large intestine and the effects of volatile fatty acids on magnesium absorption.

Endothelin-1 inhibition of cardiac ATP-sensitive K+ channels via pertussis-toxin-sensitive G-proteins

OBJECTIVE

Secretion of endothelin-1 (ET-1) and activation of cardiac ATP-sensitive K+ (KATP) channels are facilitated under myocardial metabolic stress. The aim of this study was to investigate the effects of ET-1 on KATP channels and to assess underlying mechanisms in ventricular myocytes.

METHODS

Single channel currents were measured with the voltage-clamp technique in cell-attached patches from enzymatically-isolated single guinea pig ventricular myocytes. In some experiments, the open-cell-attached mode was employed by permeating the membrane with streptolysin-O.

RESULTS

ET-1 concentration-dependently inhibited single KATP channel currents, which had been activated by metabolic poisoning, with an IC50 of 3.8 +/- 0.7 pM. BQ-123, an ETA receptor-selective antagonist, reduced the effects of ET-1. ET-1 effects were largely abolished in the myocytes pre-incubated with pertussis toxin. In the open-cell-attached mode, where the intracellular ATP concentration ([ATP]) could be virtually controlled, the effects of ET-1 were abolished. Muscarinic receptor stimulation inhibited the channels in a similar manner to ET-1, whereas beta-adrenoceptor stimulation accelerated channel activation. By analogy, ouabain also inhibited KATP channel activity under metabolic stress presumably because inhibition of the Na+/K+ pump spares subsarcolemmal ATP. ET-1 inhibited the KATP channels that had been reactivated in the continuous presence of ouabain.

CONCLUSIONS

ET-1 reversibly inhibited KATP channels. This effect appears to be mediated by an increase in subsarcolemmal [ATP] which results from inhibition of adenylate cyclase activities through PTX-sensitive G-proteins coupled to ETA receptors.

Effects of beta 1-->4 linked galactooligosaccharides on use of magnesium and calcification of the kidney and heart in rats fed excess dietary phosphorous and calcium

Magnesium deficiency was induced in male Wistar rats by adding an excess of phosphorous and calcium to the diet (1.195 g of phosphorous and 1.04 g of calcium/100 g of diet). Feeding of these animals with a diet containing beta 1-->4 linked galactooligosaccharides (4'-GOS) (5 g of 4'-GOS/100 g of diet) increased the apparent magnesium absorption ratios and the concentrations of magnesium in the serum and femur, and reduced accumulation of calcium in the kidney and heart. We speculate that the use of magnesium increased by feeding 4'-GOS to a limited extent prevented the lower magnesium status and the severity of calcification of the kidney and heart caused by excess dietary phosphorous and calcium.

Effects of calcium gluconate on the utilization of magnesium and the nephrocalcinosis in rats fed excess dietary phosphorus and calcium

The effects of calcium gluconate on the utilization of magnesium and nephrocalcinosis in male Wistar rats made magnesium-deficient by adding excess dietary phosphorus (1.195 g of phosphorus/100 g of diet) and calcium (1.04 g of calcium/100 g of diet) were compared with the effects of calcium carbonate. The effects of dietary magnesium concentration on the magnesium status and nephrocalcinosis were also examined. Adding excess dietary phosphorus and calcium decreased the apparent magnesium absorption ratios and the concentrations of magnesium in the serum and femur and increased the deposition of calcium in the kidney, and the low magnesium condition (0.024 g of magnesium/100 g of diet) aggravated the deposition of calcium and the low magnesium status. The apparent magnesium absorption ratios and femur magnesium concentration in the rats fed a calcium gluconate diet (an equimolar mixture of calcium gluconate and calcium carbonate was used as a source of calcium) were significantly higher than in the rats fed a calcium carbonate diet (only calcium carbonate was used as a source of calcium), irrespective of dietary magnesium concentration. Dietary calcium gluconate lessened the accumulation of calcium in the kidney and increased the serum magnesium concentration compared with dietary calcium carbonate, when the rats were fed the normal magnesium diet (0.049 g of magnesium/100 g of diet) but not the low magnesium diet. We speculate that the increased utilization of magnesium by feeding the calcium gluconate diet to a limited extent prevented the low magnesium status and the severity of nephrocalcinosis caused by adding excess dietary phosphorus and calcium.

Endothelin-1 inhibits L-type Ca currents enhanced by isoproterenol in guinea-pig ventricular myocytes

To investigate the action of endothelin-1 (ET-1) on L-type Ca currents (ICa,L) in guinea-pig ventricular cells, whole-cell currents were recorded at approximately 36-37 degrees C in enzymatically isolated myocytes. ET-1 (> or =10 nM) suppressed the basal ICa,L to 79+/-8% of control at 20 nM. Bath application of isoproterenol (ISO; 10 nM) enhanced ICa,L to 192+/-28% with about a -10-mV shift of its relationship with membrane potential. ET-1 concentration dependently inhibited this ISO-enhanced ICa,L with a half-maximally inhibitory concentration (IC50) of 168 pM. The inhibitory actions of ET-1 were antagonised by BQ-123 (300 nM), cyclo(D-Asp-L-Pro-D-Val-L-Leu-D-Trp), a specific ETA receptor antagonist. Histamine-enhanced ICa,L was also suppressed by ET-1, but ICa, L potentiated by internal adenosine 3',5'-cyclic monophosphate (cAMP) was unaffected. Preincubation of myocytes with pertussis toxin (PTX, at 5 microgram/ml for >60 min at 36 degrees C) completely occluded the ET-1 action. Thus, stimulation of ETA receptors by subnanomolar ET-1 inhibits ICa,L via PTX-sensitive G-proteins.

Effects of some diethylstilbestrol metabolites and analogs on cytotoxicity and aneuploidy induction in Chinese hamster V79 cells

We have previously reported the inhibitory effects of diethylstilbestrol (1) and optically active indenestrol derivatives on microtubule polymerization in vitro and their disruptive effect on cytoplasmic microtubules and cytotoxicity in cultured Chinese hamster V79 cells. In the present study, the cytotoxicities of (+-)-diethylstilbestrol oxide (2), (+)-, (-)- and (+-)-monomethyl ethers (4) of 2, (+-)-dimethyl ether (5) of 2, diethylstilbestrol pinacolone (3), E,E-dienestrol (6), Z,Z-dienestrol (7), meso-hexestrol (8), a mixture of (1R,1'S)4-hydroxyhexestrol and (1R,1'S)4'-hydroxyhexestrol (9), and the 4-hydroxy derivative (10) of diethylstilbestrol dimethyl ether were investigated in Chinese hamster V79 cells. The results indicated that the cytotoxic activity of 10 was the strongest of the compounds tested, although its activity was the almost same as that of 1. Moreover, as the activity of (-)-4 was greater than those of 2 and 1 monomethyl ethers, the effect of 4 on cytotoxic activities was elucidated. In conclusion, the present results indicate that the cytotoxic activities of hydroxylated metabolites are greater than those of each mother compound, although epoxidation of 1 leads to a product which can be broken down more readily than the parent compound.

Effect of galactooligosaccharides on calcium absorption in rats

The effect of transgalactosylated oligosaccharides (TOS), which are oligosaccharides that are unhydrolyzed in the small intestine and are fermented by the intestinal bacteria, on calcium absorption was examined in male Wistar rats for 10 days. The apparent calcium absorption ratios and the apparent retention ratios were significantly higher in the rats fed TOS-containing diets (5 or 10 g/100 g of diet). In the second experiment, the cecum was ligated in situ and calcium absorption from the cecum was observed after injecting TOS into the cecal lumen. Four hours after the injection, the calcium concentration in the cecal vein of the rats given TOS was significantly higher than that of the control. The calcium content in the liquid phase of the cecal lumen and the liquid phase weight were also increased by the injection of TOS into the cecum. Although the extent of calcium absorption from the cecum of rats fed TOS is due to overall calcium absorption is not known, under the experimental conditions used in the present study the stimulatory effect of TOS on calcium absorption may be partly associated with increased solubility of calcium and the fluid content in the intestinal lumen.

Effect of galactooligosaccharides on calcium absorption and preventing bone loss in ovariectomized rats

The effects of galactooligosaccharides (GOS), a mixture of galactosyl oligosaccharides formed from lactose by the transgalactosyl reaction of beta-D-galactosidase derived from Bacillus circulans, on calcium absorption and prevention of bone loss were examined in ovariectomized (OVX) Wistar rats. Rats fed on a diet containing GOS absorbed calcium more efficiently than those on the control diet after 8-10 days and 18-20 days, and the bone (femur and tibia) ash weight and tibia calcium content of OVX rats fed on the GOS diet were significantly higher than those of the control animals. Although the serum total cholesterol of the ovariectomized rats was significantly elevated, GOS produced a significant hypocholesterolemic effect in the OVX rats. GOS, which is fermented by bacteria in the lower part of the intestine, enhanced volatile fatty acid production, and thus prevented bone loss and lower serum total cholesterol concentration in the ovariectomized rats.

Development of continuous recirculating peritoneal dialysis using a double lumen catheter

Continuous recirculating peritoneal dialysis (CRPD) was newly introduced to improve solute removal efficiency in conventional dialysis therapies such as hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). In CRPD, a part of the dialysate in the peritoneal cavity was drained through a double-lumen catheter and purified by an extracorporeal dialyzer. Urea removal characteristics in CRPD were examined in a canine study. In this study, a recirculation-dialysis experiment using a dog weighing 9.0 kg was carried out under 100 and 200 ml/min of flow for recirculating and delivered dialysates, respectively. An FB-50H (Nipro Medical Industries, Ltd., Osaka, Japan) composed of cellulose diacetate membrane with 0.5 m2 of surface area and Dianeal-1.5 (Baxter Limited Laboratories, Tokyo, Japan) containing urea were used as the extracorporeal dialyzer and dialysate. Urea peritoneal and dialyzer dialysances (DBP and DBD) were 3.05 and 33.3 ml/min by computer simulation using a compartment model for CRPD. This DBP value can be estimated as 20.3 ml/min for a 60 kg human. From this result, time-averaged value for BUN over an 8 hr/day CRPD, combined with three exchanges/day as CAPD is estimated to be 34.3 mg/dl, which is much lower than 45.2 mg/dl for a 12 hr/week HD, or 53.0 mg/dl for conventional CAPD.

Thrombolytic properties of staphylokinase

We evaluated the properties of recombinant staphylokinase in comparison with those of tissue-type plasminogen activator (t-PA) and streptokinase (SK). The presence of fibrin(ogen) fragment FCB-2 in the reaction mixture increased plasminogen activation by staphylokinase more than 20-fold. Such characteristics are similar to those of t-PA. On the other hand, SK was not affected by the presence of FCB-2. The thrombolytic properties of staphylokinase were studied in a system consisting of a radioactive human plasma clot (125I-fibrinogen-labeled) suspended in the circulating citrated plasma. Significant thrombolysis (50% in 3 hours) was obtained with 2 micrograms/mL of staphylokinase and 4.45 micrograms/mL t-PA, as compared with 12 micrograms/mL for SK. The relative molar potency of staphylokinase, calculated from the molecular weight, was about two times more effective than that of SK, but about half of that of t-PA. Systemic fibrinolytic activation and fibrinogen breakdown was not observed with staphylokinase or t-PA, but was observed with SK. The thrombolytic efficiency of staphylokinase, which was calculated as the ratio of the degree of thrombolysis/the degree of fibrinogenolysis, was about five times greater than that of SK, and about half of that of t-PA. These findings suggest that staphylokinase has higher specific thrombolytic properties and lesser fibrinogenolytic properties than those of SK.

Mechanism of fibrin-specific fibrinolysis by staphylokinase: participation of alpha 2-plasmin inhibitor

When the extent of plasminogen activation by staphylokinase (SAK) or streptokinase (SK) was measured in human plasma, SAK barely induced plasminogen activation, whereas SK activated plasminogen significantly. When the plasma was clotted with thrombin, the plasminogen activation by SAK was markedly enhanced, but that of SK was little enhanced. Similarly, in a purified system composed of plasminogen, fibrinogen and alpha 2-plasmin inhibitor (alpha 2-PI, alpha 2-antiplasmin), such a fibrin clot increased the activity of SAK significantly. However, when alpha 2-PI was removed from the reaction system, enhancement of the SAK reaction was not observed. In addition, SAK as distinct from SK, showed very little interference with the action of alpha 2-PI. Plasminogen activation by SAK is thus essentially inhibited by alpha 2-PI, but this reaction is not inhibited in fibrin clots. These results suggest that SAK forms a complex with plasminogen, which binds to fibrin and induces fibrinolysis.

Effect of soybean protein on coprostanol production and cholesterol metabolism in cholesterol-fed rats

The effect of soybean protein on coprostanol production and cholesterol metabolism was studied in cholesterol-fed rats. Plasma cholesterol was decreased in the soybean protein diet group compared to the casein diet group. Although coprostanol was produced more in rats fed soybean protein than in those fed casein, no difference was observed in the levels of total neutral steroids at any part of the intestine. The activity of microbial conversion from cholesterol to coprostanol was evidently high in rats fed soybean protein. The total amount of neutral steroids excreted in feces had a tendency to increase. These data seem to indicate that the increase of the unabsorbed soybean protein causes the increase of intestinal coprostanol production.

Selective inhibition by benzaldehyde of the uptake of nucleosides and sugar into simian virus 40-transformed cells

The effects of benzaldehyde, which has been found in figs as a carcinostatic element, were studied on the uptake of nucleosides, 2-deoxy-D-glucose, and amino acids into simian virus 40-transformed rat fibroblast cells (SV40-transformed cells) and into the parent normal cells (normal cells). Benzaldehyde, at the concentrations of 25 to 100 microgram/ml at which the selective growth inhibition against SV40-transformed cells was revealed, markedly inhibited the uptake of thymidine, other nucleosides, and 2-deoxy-D-glucose into SV40-transformed cells without any significant inhibition of the uptake of these compounds into normal cells. The uptake of amino acids into both transformed and normal cells was not inhibited by benzaldehyde. Selectively cytotoxic benzaldehyde-related compounds such as 4-nitrobenzaldehyde, 4-acetaminobenzaldehyde, thiophene-3-carboxaldehyde, etc., showed a similar inhibitory effect on thymidine uptake. The deprivation of glucose from the incubation medium strikingly diminished the inhibitory effect of benzaldehyde on the uptake of thymidine and 2-deoxy-D-glucose into SV40-transformed cells. The intracellular adenosine 5'-triphosphate level of SV40-transformed cells was reduced to less than one-half by treatment with benzaldehyde (50 microgram/ml) in glucose-containing medium. This effect was not observed in glucose-free medium. Treatment with benzaldehyde caused no change of the intracellular adenosine 5'-triphosphate level of normal cells. Based on the above results, the selective cytotoxicity of benzaldehyde was attributed to the reduction of intracellular adenosine 5'-triphosphate level of transformed cells, accompanied by the poor uptake of thymidine, glucose, etc., into SV40-transformed cells.

Effect of adrenocorticotrophin on intracellular cholesterol transport

The rate of side-chain cleavage of cholesterol by mitochondria derived from mouse adrenal tumour cells was measured. Incubation of the cells in the presence of adrenocorticotrophin (ACTH) for periods of up to 1 h was without effect on the subsequent side-chain cleavage by mitochondria. However, if the cells were incubated in the presence of aminoglutethimide phosphate (0·76 mmol/l), addition of ACTH (final concentration 86 u./l) to the medium containing the cells increased the subsequent rate of side-chain cleavage by the isolated mitochondria. This response reached a maximum after incubation of cells with ACTH for 2 h and decayed when the isolated mitochondria were left at 0 °C, although a significant difference was still apparent after 120 min. Similar stimulation of mitochondrial side-chain cleavage by ACTH was observed when the reaction was inhibited by anaerobiosis instead of aminoglutethimide phosphate. Addition of dibutyryl cyclic AMP, at final concentrations greater than 10−5 mol/l, to cells during incubation with aminoglutethimide phosphate (0·76 mmol/l) also stimulated the conversion of cholesterol to pregnenolone by the mitochondria.

Provided the adrenal tumour cells were incubated with aminoglutethimide, or anaerobically, the mean cholesterol content of the inner mitochondrial membrane was significantly higher (P < 0·01) when ACTH was included in the incubation medium than when it was not.

It is concluded that ACTH increases the movement of cholesterol to the mitochondrial membrane which contains the side-chain cleavage enzyme system and that part of this cholesterol is used for the enhanced conversion of cholesterol to pregnenolone brought about by ACTH.

Composition of lipids bound to pure cytochrome P-450 of cholesterol side-chain cleavage enzyme from bovine adrenocortical mitochondria

Phospholipids bound to highly purified cytochrome P-450 from bovine adrenocortical mitochondria, part of the enzyme complex responsible for catalyzing the conversion of cholesterol to pregnenolone, have been examined for comparison with the bulk phospholipids of the mitochondria from the same tissue. In both cases, the major phospholipids are phosphatidylcholine (PC) (37%) and phosphatidylethanolamine (PE) (56%), as well as smaller amounts of sphingomyelin and diphosphatidylglycerol. The fatty acid compositions of the four classes of phospholipids and of the neutral lipids bound to the pure enzyme are indistinguishable from those of the respective mitochondrial lipids. They are also similar to those of mitochondria from other organs except for high levels of arachidonate and low levels of diphosphatidylglycerol.

Adrenocortical cytochrome P-450 side chain cleavage. Preparation of membrane-bound side chain cleavage system from purified components

Soluble cytochrome P-450 from bovine adrenocortical mitochrondria, capable of side chain cleavage, can be incorporated into membranes prepared by dispersion of phospholipids in aqueous buffer when cholate is added to the membrane suspension. In addition, the complete protein side chain cleavae system (i.e. including the ancillary proteins adrenodoxin and adrenodoxin reductase and the substrate cholesterol) can be incorporated into such membranes so that on addition of TPNH, pregnenolone is formed. These components remain in the membrane through gel filtration (which removes almost all the cholate) and sedimentation through sucrose density gradients which separate vesicles without protein and soluble enzyme from the membrane-bound P-450 remains associated with the membrane during and following lysis of vesicles. The vesicles which do not leak [14C]glucose were seen on electron microscopy to show a mean diameter of 350 to 450 A. A number of phospholipids are capable of accomodating P-450 in this manner: mitochondrial lipid extracts, synthetic dipalmitoyl phosphatidylcholine, synthetic dipalmitoyl phosphatidylserine, and egg lecithin, separately or in various combinations. Cholesterol is not necessary for incorporation of the side chain cleavage system. Membrane-bound P-450 shows a Vmax of 28.1 nmol of pregnenolone/min/mg of protein, more than 10 times that of soluble P-450. The spectral properties of the soluble P-450 are altered to become predominantly low spin in the membrane and the enzyme is more stable at 4 degrees C than is soluble p-450.