In Vitro Utilization of Amylopectin and High-Amylose Maize (Amylomaize) Starch Granules by Human Colonic Bacteria

It has been well established that a certain amount of ingested starch can escape digestion in the human small intestine and consequently enters the large intestine, where it may serve as a carbon source for bacterial fermentation. Thirty-eight types of human colonic bacteria were screened for their capacity to utilize soluble starch, gelatinized amylopectin maize starch, and high-amylose maize starch granules by measuring the clear zones on starch agar plates. The six cultures which produced clear zones on amylopectin maize starch- containing plates were selected for further studies for utilization of amylopectin maize starch and high-amylose maize starch granules A (amylose; Sigma) and B (Culture Pro 958N). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to detect bacterial starch-degrading enzymes. It was demonstrated that Bifidobacterium spp., Bacteroides spp., Fusobacterium spp., and strains of Eubacterium, Clostridium, Streptococcus, and Propionibacterium could hydrolyze the gelatinized amylopectin maize starch, while only Bifidobacterium spp. and Clostridium butyricum could efficiently utilize high-amylose maize starch granules. In fact, C. butyricum and Bifidobacterium spp. had higher specific growth rates in the autoclaved medium containing high-amylose maize starch granules and hydrolyzed 80 and 40% of the amylose, respectively. Starch-degrading enzymes were cell bound on Bifidobacterium and Bacteroides cells and were extracellular for C. butyricum. Active staining for starch-degrading enzymes on SDS-PAGE gels showed that the Bifidobacterium cells produced several starch-degrading enzymes with high relative molecular (M_r) weights (>160,000), medium-sized relative molecular weights (>66,000), and low relative molecular weights (<66,000). It was concluded that Bifidobacterium spp. and C. butyricum degraded and utilized granules of amylomaize starch.     

Statistical Properties and Control Algorithms of Recursive Quantile Estimators

The present study is an extension of the investigations made by Grieszbach and Schack (1993) where the recursive estimators of the quantile were introduced. Attention is focused on statistical properties and on the controlling of these estimators in order to reduce their variance and to improve their capability of adaptation. Using methods of stochastic approximation, several control algorithms have been developed, where both the consistent and the adaptive estimation are considered. Due to the recursive computation formula the estimators are suitable for the analysis of large data sets and for sets whose elements are obtained sequentially. In this study, application examples from the analysis of EEG‐records are presented, where quantiles are used as threshold values.     

Selected nuclear LINE elements with mitochondrial-DNA-like inserts are more plentiful and mobile in tumor than in normal tissue of mouse and rat

The nuclear DNA of normal and tumor mouse and rat tissue was examined for mitochondrial-DNA-like inserts by means of the Southern blot technique. The two probes were ³²P-labeled cloned mitochondrial DNA. KpnI, which doesn't cut either mitochondrial DNA, was one of the restriction enzymes, while the enzymes that fragment mitochondrial DNA were for mouse and rat PstI and BamHI, respectively. When KpnI alone was used in the procedure a nuclear LINE family whose elements had mitochondrial-DNA-like insertions was selected. Such elements were much more abundant in tumor than in normal tissue. The results with PstI alone and BamHI alone and each combined with KpnI indicated that there were mobile LINE elements with mitochondrial-DNA-like inserts in the nuclear genome of tumor. The mouse tissues were normal liver and a transplantable lymphoid leukemic ascites cell line L1210 that had been carried for 40 years. The rat tissues were normal liver and a hepatoma freshly induced by diethylnitrosoamine in order to minimize the role of 40 years of transplantation. Our unitary hypothesis for carcinogenesis of 1971, which suggested these experiments, has been augmented to include mobile nuclear elements with inserts of mitochondrial-DNA-like sequences. Such elements have been related to diseases of genetic predisposition such as breast cancer and Huntington's disease. J. Cell. Biochem. 68:100–109, 1998. © 1998 Wiley-Liss, Inc.     

Intimal hyperplasia following vascular injury is not inhibited by an antisense thrombin receptor oligodeoxynucleotide

Thrombin is a multifunctional serine protease with central functions in hemostasis, but demonstration of its role in the initiation and maintenance of cell proliferation which occurs following vascular injury is still lacking. To determine the role played by thrombin and its receptor in neointimal accumulation of smooth muscle cells in a rabbit carotid artery model, we have used an 18 mer antisense phosphorothioate oligonucleotide (ODN) directed against the translation initiation region of the human thrombin receptor gene. The antisense ODN inhibited in a dose-dependent manner thrombin- or thrombin receptor activating peptide-induced human aortic smooth muscle cell proliferation. The growth-inhibitory effect of thrombin receptor antisense ODN was preventable by an excess of sense oligomer and specific for thrombin. The suppression of growth was accompanied by a marked decrease of the level of thrombin receptor expression as evidenced by [¹²⁵l]-thrombin binding to smooth muscle cells. Under the same experimental conditions, the corresponding sense ODN was inactive. The effect of the antisense ODN on intimal smooth muscle hyperplasia in rabbit carotid arteries subjected to endothelial injury was then investigated. The topical application of the antisense (500 μg/artery) but not the sense ODN dissolved in F127 pluronic gel around the injured artery resulted, 2 weeks after the application, in a dramatic reduction of the expression of the thrombin receptor mRNA and protein levels as determined by in situ hybridization and immunohistochemistry. However, intimal smooth muscle cell accumulation as estimated by an intimal to medial cross-sectional area ratio was reduced only by 2.7% (vs. 10.3% for the sense ODN), whereas r-hirudin (200 μg/kg/day, sc), a potent direct thrombin inhibitor significantly reduced the formation of neointima in denuded carotid arteries (35.4% inhibition, P = 0.03). J. Cell. Physiol. 170:106–114, 1997. © 1997 Wiley-Liss, Inc.     

Bacterial survival strategies suggest rethinking cancer cooperativity

Despite decades of a much improved understanding of cancer biology, we are still baffled by questions regarding the deadliest traits of malignancy: metastatic colonization, dormancy and relapse, and the rapid evolution of multiple drug and immune resistance. New ideas are needed to resolve these critical issues. Relying on finding and demonstrating parallels between collective behavior capabilities of cancer cells and that of bacteria, we suggest communal behaviors of bacteria as a valuable model system for new perspectives and research directions. Understanding the ways in which bacteria thrive in competitive habitats and their cooperative strategies for surviving extreme stress can shed light on cooperativity in tumorigenesis and portray tumors as societies of smart communicating cells. This may translate into progress in fathoming cancer pathogenesis. We outline new experiments to test the cancer cooperativity hypothesis and reason that cancer may be outsmarted through its own 'social intelligence'.     

Ciliary neurotrophic factor upregulates ubiquitin-proteasome components in a rat model of neuronal injury

Neuronal injury triggers the release of ciliary neurotrophic factor (CNTF), promoting local neuronal repair but producing systemic effects of anorexia and lean body weight loss. Due to the rapid rate of systemic protein loss stimulated by CNTF, we hypothesized involvement of the hepatic ubiquitin-proteasome proteolytic (UPP) pathway in CNTF-induced proteolysis. To assess the role of central CNTF in systemic UPP regulation, we measured hepatic UPP mRNA and proteasome activity in a rat model of neuronal injury and determined alterations induced by intracerebroventricular (ICV) administration of CNTF-neutralizing antibody or additional exogenous CNTF. We also assessed proteolytic parameters and nutritional status by measuring caloric intake, body weight, and protein levels. We produced neuronal injury by implanting a lateral ventricle cannula and giving daily ICV saline bolus injections, which increased hepatic 20S proteasome mRNA and enzymatic activity while reducing caloric intake, body weight, and protein levels compared to controls. Administration of ICV anti-CNTF antibodies (but not control antibodies) prevented these effects. Addition of exogenous CNTF augmented the weight loss along with the increases in 20S proteasome mRNA and proteolytic activity induced by neuronal injury. We conclude that CNTF decreases lean body weight through a combination of appetite inhibition and UPP pathway activation.