Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The plus-strand replication origin of bacteriophage fl has a bipartite structure consisting of a required core origin region and an adjacent A + T-rich enhancer sequence that potentiates replication approximately 100-fold. The core origin binds the initiator protein (gpII) and the enhancer binds the Escherichia coli integration host factor (IHF). gpII binds the core origin in two steps, forming a binding intermediate (complex I) and a functional complex for nicking (complex II). We have used a double-label gel binding assay to determine the stoichiometry of the gpII-origin interaction. The results indicate that complex I contains two gpII molecules per origin, and complex II contains four gpII molecules per origin. Enhancer-independent mutations in gpII allow wild-type levels of replication in the absence of either the enhancer or IHF. We have examined the binding of an enhancer-independent gpII mutant (mp1) protein to the replication origin. The mp1 mutation in gpII (Met40----Ile) increases the co-operativity with which the protein binds to form complex II. In addition, the mutant gpII forms both complexes with a DNA fragment containing only two (beta-gamma) of the three repeats from the core origin sequence, while the wild-type protein forms only complex I with this fragment. We discuss how a mutation that increases the co-operativity of binding of an initiator protein might stimulate DNA replication.
J Mol Biol 1990 Jan 05
PMID:Replication enhancer-independent mutation increases the co-operativity with which an initiator protein binds its origin. 240 67

Compensatory hypertrophy of the rat plantaris muscle (PLT) was induced by ipsilateral gastrocnemius muscle ablation. Following 8 weeks (wks) of hypertrophy, hindlimbs were cast immobilized (HI) for 4 weeks after which weight bearing was unrestricted for 8 wks (recovery). Compensatory hypertrophy increased PLT wet weight/body weight ratio (83%), muscle fiber cross-sectional areas (1.5 to 2 fold), and the percent of slow oxidative (%SO) fibers (2 fold) in the experimental compared to the contralateral sham control muscle. PLT protein content and maximal activities of phosphofructokinase (PFK), mitochondrial glycerol phosphate dehydrogenase, and succinate dehydrogenase were unaltered with muscle hypertrophy. HI produced significant decreases in PFK activity (50%) and muscle fiber cross-sectional areas (50%) but did not significantly change the histochemical myofibrillar ATPase profile. Following remobilization, muscle weight/body weight ratio and maximal enzyme activities recovered to that of aged matched controls. Muscle fiber areas returned to pre-immobilization sizes but were approximately 25% smaller than aged matched control hypertrophy muscles. The %SO fibers in the hypertrophied muscle remained higher than controls but did not return to pre-immobilization values. These results indicate that biochemical and histochemical characteristics of hypertrophied rat PLT recover from HI during 8 wks of normal weight bearing similar to that of normal control muscle. However, the recovery time period was insufficient to allow complete compensation of fiber size to that of the age-matched control animals.
Mol Cell Biochem 1989 Oct 05
PMID:Effect of hindlimb immobilization and recovery on compensatory hypertrophied rat plantaris muscle. 253 7

The effect of Ca2+-homopantothenate (HOPA) treatment (250 mg/kg for 5 d) has been studied by evaluating the specific activity of enzymes related to: glycolytic pathway (hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase), tricarboxylic acid cycle (citrate synthase, malate dehydrogenase), mitochondrial electron transfer chain (succinate dehydrogenase, cytochrome oxidase), NADH redox state (NADH cytochrome c reductase), acetylcholine metabolism (acetylcholinesterase), and glutamate metabolism (glutamate dehydrogenase). The enzymatic activity assays were performed on homogenate in toto, nonsynaptic mitochondria and synaptosomes isolated from: cerebral cortex, hippocampus, striatum, hypothalamus, medulla oblongata, and cerebellum of normoxic rats and rats submitted to intermittent normobaric hypoxia (90:10, N2:O2). In normoxic rats, HOPA was unable to induce any modification. Hypoxia per se induced a decrease in the activity of synaptosomal cytochrome oxidase in cerebral cortex, hippocampus, and cerebellum.
Mol Chem Neuropathol 1989 Jun
PMID:Effect of Ca2+-homopantothenate and mild hypoxia on some enzyme activities evaluated in subcellular fractions from different rat brain regions. 254 16

The expression of a number of enzymes involved in drug metabolism, membrane function etc. was compared in hyperplastic and neoplastic lesions of the rat bladder and in human bladder tumours. Transitional cell carcinomas (TCC) in both rat and Man were characterized by decreased alkaline phosphatase (ALP) and increased gamma-glutamyl transpeptidase (GGT), beta-glucuronidase (beta-G1), succinate dehydrogenase (SD) and glucose-6-phosphate dehydrogenase (G6PD) activities. In addition, binding for antibodies specific for different cytochrome P-450 species (UT50, PB3a, MC1, MC2) and microsomal epoxide hydrolase (mEHb) was elevated in both murine and human tumours. Comparison of the enzyme phenotype in hyperplastic lesions induced by freeze ulceration or uracil administration with that in preneoplastic papillary or nodular hyperplasia (PNH) and TCC suggested, however, that most of the alteration in enzyme content or activity was non-specific and related to requirements for epithelial cell proliferation. On the other hand, the decreased ALP, and increased GGT and beta-G1 activity appeared more directly related to neoplastic transformation. The results suggested that qualitative differences exist between reactive hyperplasia and preneoplastic or neoplastic lesions in the urinary bladder. The finding of increased cytochrome P-450, in clear contrast to the reduction characteristic of preneoplastic hepatic lesions, may be important with regard to the observed difference in neoplastic transformation between the bladder and liver in response to drug metabolising enzyme inducers.
Virchows Arch B Cell Pathol Incl Mol Pathol 1989
PMID:Comparison of enzyme phenotypes in human bladder tumours and experimentally induced hyperplastic and neoplastic lesions of the rat urinary bladder. A combined histochemical and immunohistochemical approach. 256 27

Young adult Wistar rats received 40 mg/kg of cyclosporin perorally for 21 days. Cyclosporin induced almost total disappearance of thymic medulla, whereas the cortex remained preserved. Although the density of cortical macrophages did not change significantly, their characteristics altered markedly and they became enlarged and rounded. In addition to an increase in acid phosphatase and nonspecific esterase activities, cortical macrophages developed very strong succinic dehydrogenase and chloroacetate esterase activities and a fine, granular, aldehyde fuchsin-positive cytoplasmic content. However, these cytoplasmic granules were PAS-negative and were not sudanophilic. Cortical macrophages retained their normal antigenic properties (which were studied by the use of ED1, ED2 and R-MC 41 monoclonal antibodies). Phagocytic cells in the remaining medullary islands retained their usual characteristics. The changes in cortical macrophages after cyclosporin treatment are discussed, especially in relation to the characteristics of macrophages of the cortico-medullary zone in the normal rat thymus.
Virchows Arch B Cell Pathol Incl Mol Pathol 1989
PMID:Macrophages of the rat thymus after cyclosporin treatment. Histochemical, enzymehistochemical and immunohistochemical study. 256 84

Corticosteroids have been shown to produce a myopathy of peripheral skeletal muscle, characterized predominantly by Type II fiber atrophy. To determine if similar histologic and histochemical changes occur in the diaphragm and whether the in vitro contractile properties of this muscle are adversely affected by steroids, we studied two groups of hamsters. The experimental group received triamcinolone while a control group received saline, both given daily for 3 wk as i.m. injections. Soleus (Sol) and extensor digitorum longus (EDL) muscles and costal diaphragm muscle sections were stained for histologic (hematoxylin and eosin, modified Gomori trichrome) and histochemical (myosin ATPase, succinate dehydrogenase [SDH]) analysis. Muscle fiber proportions and cross-sectional areas (CSA) were measured from myosin ATPase sections. In vitro studies of isometric contractions were carried out on small strips of costal diaphragm, measuring maximal isometric twitch (Pt) and tetanus (Po) tensions, time to peak tension (TTP), half relaxation time (1/2 RT), force-frequency relationship, and fatigue characteristics (60 Hz tetani; duty cycle, 0.5). Triamcinolone treatment resulted in no change in muscle fiber proportions. There was no effect on Type I fiber CSA; however, there was Type IIa (Sol, EDL) and Type IIb (diaphragm, EDL) fiber atrophy in triamcinolone-treated animals. Pt and Po (normalized for weight) of diaphragm strips were not different. There was a prolongation in TTP and 1/2 RT, a left shift in the force-frequency curve, and a reduced fatiguability of triamcinolone-treated diaphragm (P less than 0.05). We conclude that a steroid myopathy could be explained by a loss of muscle mass (Type IIb fiber atrophy) rather than an intrinsic impairment in contractile function.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1989 Sep
PMID:Pathologic changes and contractile properties of the diaphragm in corticosteroid myopathy in hamsters: comparison to peripheral muscle. 262 59

In this paper we report that three different rat liver mitochondrial fractions, differing in density, exhibit differential effects when the animals are made hypo- or hyperthyroid. The investigations have been performed by correlating the protein content, the succinic dehydrogenase behaviour and the respiratory features of the three fractions in different thyroid states with morphometric-stereologic analysis the electron micrographic level. The results indicate that the thyroid hormone influences both the mass and the functionality of the heavy (H) and light (L) fraction. In hypothyroid rats the H fraction increases (+43%) while the L fraction decreases (-32%) and their respiratory activity is drastically reduced. Adenosine triphosphate (ATP) synthesis in the H fraction is also inhibited. Triiodothyronine (T3) administration to the above animals restores the values observed in control rats. At morphometric level we note in hypothyroid rats an increase in the number of mitochondria together with a concomitant increase in the average volume of a single mitochondrion. We are inclined to explain the above results through an action exerted by T3 on a hypothetical mitochondrial cycle starting with the formation of light organelles from heavy ones.
Mol Cell Endocrinol 1989 Mar
PMID:The effect of thyroid state on respiratory activities of three rat liver mitochondrial fractions. 274 21

The effect of calcitonin (synthetic [Asu1,7]eel) on the exchangeable Ca2+ transport was investigated in isolated rat hepatocytes by measuring 45Ca2+ uptake. Calcitonin (CT) increased the uptake of Ca2+ with 74.3 pM giving a half-maximal effect. The action of CT was evident within 5 min after the hormone addition to the cells, and the increase in Ca2+ uptake was maintained during 60 min. The increase in Ca2+ uptake caused by CT was dependent on extracellular Ca2+ concentration. On the other hand, the activity of mitochondrial succinate dehydrogenase in hepatocytes was significantly increased by addition of CT (74.3 pM) to the cells in the presence of 1.3 mM Ca2+, while the hormonal effect was not seen in the absence of added Ca2+. The presence of Ca2+ ionophore A23187 (0.1 and 1.0 microM) abolished the increase in enzyme activity caused by CT addition to the cells. It is proposed that CT can increase the rate of uptake of exchangeable CA2+ by hepatocytes, and that the hormone causes the elevation of mitochondrial succinate dehydrogenase activity which is mediated through Ca2+.
Mol Cell Endocrinol 1989 Apr
PMID:Effect of calcitonin on exchangeable calcium transport in isolated rat hepatocytes. 274 32

The heterogeneity of a synaptosomal preparation was studied by the use of affinity partitioning in combination with centrifugal counter-current distribution. Hexaethonium-poly(ethyleneglycol) was used as the extracting agent. The fractions were analyzed for: light scattering, protein, choline acetyltransferase, L-glutamate decarboxylase, glutamine synthetase, 2',3'-cyclicnucleotide-3'-phosphohydrolase, acetylcholinesterase and succinate dehydrogenase. The material was fractionated into three main fractions which differed in their content of marker-enzymes.
Mol Cell Biochem 1989 Jun 01
PMID:Heterogeneity of a crude synaptosomal preparation, studied by affinity partitioning using hexaethonium-poly(ethylene glycol). 277 Jul 19

The study describes regional changes of xanthine oxidase and succinate dehydrogenase activities as shown by the ischemic and reperfused small intestine of the rat. The results are obtained with enzyme histochemical methods, including densitometrical verifications, and are substantiated with biochemical enzyme determinations. The decrease of xanthine oxidase activity was best visible in the anoxic duodenum and jejunum, where the findings of histochemical enzyme determinations agreed with those achieved biochemically. The activities of succinate dehydrogenase as measured densitometrically may serve as a further control, considering also the typical intracellular distribution of the reaction products.
Cell Mol Biol 1989
PMID:Regional histochemical aspects of xanthine oxidase activity in ischemic and reperfused small intestine of the rat. 277 76


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