The Activities of Antioxidant Enzymes and Monoamine Oxidase and Uncoupling Protein 1 Content in Brown Fat of Hypo- and Hyperthyroid Rats

We have studied the activities of antioxidant enzymes (AOE), namely, copper-zinc superoxide dismutase (CuZnSOD), manganese superoxide dismutase (MnSOD), and catalase (CAT), and the activity of catecholamine-degrading enzyme monoamine oxidase (MAO) and uncoupling protein 1 (UCP1) content in brown fat (BF) of hypo- and hyperthyroid rats. We found that hypothyroidism decreased BF UCP1 content and increased MAO, MnSOD, and CAT activities. T3 increased UCP1 content and MnSOD activity and decreased CuZnSOD, MAO, and CAT activities, while T4 significantly altered (decreased) only CAT activity. This study shows that UCP1 content and MAO and AOE activities in rat BF are notably affected by changed thyroid status.

Radioimmunoscintigraphy of colorectal carcinomas with three different radiopharmaceuticals

The aim of the study was evaluation of the clinical reliability of the immunoscintigraphy for the detection of metastases and recurrences of colorectal carcinomas using three different radiopharmaceutical substances. With IMACIS 1, the number of true negative findings (TN) was 4/7 and true positive (TP) 3/7, while in one patient, the results of immunoscintigraphy significantly influenced the therapeutical management. With INDIMACIS 19-9, there were 2/8 TN and 6/8 TP. In three patients, immunoscintigraphy results influenced patient further management. With ONCOSCINT in 2 patients findings were TN, in one FN and in one FP. In 3 patients, immunoscintigraphy influenced the management of the patient. Other imaging methods (CT, US, MRI) have advantage in detection of liver metastases, while immunoscintigraphy is more specific for the assessment of reccurences of the abdominal tumors. Thus immunoscintigraphy should be applied in patients with suggested recurrences and inconclusive outcome of routine diagnostic workup.

Effect of the acute crowding stress on the rat brown adipose tissue metabolic function

Our previous results have shown that metabolic and thermal stressors influence interscapular brown adipose tissue (IBAT) metabolic activity by increasing oxygen consumption and, consequently, altering the toxic reactive oxygen species (ROS) production and the antioxidative system activity. Since there is not enough evidence about the effect of psychosocial stressors on these processes, we studied the effect of acute crowding stress on the IBAT and hypothalamic monoamine oxidase (MAO) activity as well as IBAT antioxidative enzymes, manganese (MnSOD), copper-zinc superoxide dismutase (CuZnSOD) and catalase (CAT), as the relevant indicators of IBAT metabolic alternations under the stress exposure and the returning of animals to control conditions. The results indicated that acute crowding stress did not change the hypothalamic and IBAT MAO activities, the generation of ROS and, consequently, the IBAT CuZnSOD and CAT activities. However, all three antioxidative enzymes were affected only after the recovery period. It seems that peripheral overheating of rats during acute crowding changes the stress nature, by becoming more thermal than psychosocial and by suppression the hypothalamic efferent pathways involved in the IBAT thermogenesis regulation. However, it seems that returning of the animals to the control conditions after the stress termination causes the reactivation of IBAT thermogenesis with tendency to normalise the body temperature.

SOD2 overexpression: enhanced mitochondrial tolerance but absence of effect on UCP activity

We have created P1 artificial chromosome transgenic mice expressing the human mitochondrial superoxide dismutase 2 (SOD2) and thus generated mice with a physiologically controlled augmentation of SOD2 expression leading to increased SOD2 enzyme activities and lowered superoxide levels. In the transgenic mice, effects on mitochondrial function such as enhanced oxidative capacity and greater resistance against inducers of mitochondrial permeability were observed. Superoxide in the mitochondrial matrix has been proposed to activate uncoupling proteins (UCPs), thus providing a feedback mechanism that will lower respiratory chain superoxide production by increasing a proton leak across the inner mitochondrial membrane. However, UCP1 and UCP3 activities and mitochondrial ATP production rates were not altered in isolated mitochondria from SOD2 transgenic mice, despite lowered superoxide levels. Globally, the transgenic mice displayed normal resting metabolic rates, indicating an absence of effect on any UCP activities, and normal oxygen consumption responses after norepinephrine injection. These results strongly suggest that endogenously generated matrix superoxide does not regulate UCP activity and in vivo energy expenditure.

Rupestris stem pitting associated virus isolates are composed by mixtures of genomic variants which share a highly conserved coat protein

Broad spectrum primers were used to amplify a fragment comprising the CP gene and putative ORF6 by RT-PCR from ds-RNA templates originating from 46 Portuguese varieties, totalling 190 samples, including some wild Vitis ssp sylvestris vines, and 2 vines from Slovenia. SSCP analysis was used as a preliminary screen to avoid cloning and sequencing very similar variants. Four groups of variants were recognized. In pair wise comparisons between nucleotide sequences the minimal homology found was 81%. In case of the cultivated varieties, no relationship could be seen between the phylogenetic groups and geographic origin or grape variety. Several isolates were found harbouring mixed infections with genomic variants from different groups, but the mixing did not lead to an extensive recombination between them. The deduced amino-acid sequences revealed a conserved CP subjected to strong purifying selection pressure. Analysis of the selection pressure operating on the putative ORF6 suggests that this ORF does not exist. Previously produced polyclonal antiserum raised against the recombinant CP of RSPaV expressed in Escherichia coli was shown to be able to detect all four groups of variants of RSPaV included in this study, which might enable the diagnosis of the virus on a serological basis.

PPARgamma in the control of brown adipocyte differentiation

The effects of fatty acids and retinoic acid (carotene) on brown adipose tissue differentiation are mediated by activation of the transcription factors PPARgamma and PPARalpha in combination with RXR. There is good support for the idea that activated PPARgamma promotes adipogenesis also in brown adipose tissue. However, the issue is more complex concerning the full differentiation to the brown adipocyte phenotype, particularly the expression of the brown-fat-specific marker UCP1. The effect of norepinephrine on PPARgamma gene expression, at least in-vitro, is negative, PPARgamma-ablated brown adipose tissue can express UCP1, and PGC-1alpha coactivates other transcription factors (including PPARalpha); thus, the significance of PPARgamma for the physiological control of UCP1 gene expression is not settled. However, importantly, the effects of PPAR agonists demonstrate the existence of a pathway for brown adipose tissue recruitment that is not dependent on chronic adrenergic stimulation and may be active in recruitment conditions such as prenatal and prehibernation recruitment. The ability of chronic PPARgamma agonist treatment to promote the occurrence of brown-fat features in white adipose tissue-like depots implies a role in anti-obesity treatment, but this will only be effective if the extra thermogenic capacity is activated by adrenergic stimulation.

An unusual presentation of “silent” disseminated pancreatic neuroendocrine tumor

To present a patient diagnosed with pancreatic carcinoid that was extremely rare and produced an atypical carcinoid syndrome. We reported a 58-year old male patient who presented with long standing, prominent cervical lymphadenopathy and occasional watery diarrhea. Pathohistological and immunohistochemical examination of lymph node biopsy showed a metastatic neuroendocrine tumor, which was histological type A of carcinoid (EMA+, cytokeratin+, CEA-, NSE+, chromogranin A+, synaptophysin+, insulin-). Bone marrow biopsy showed identical findings. Primary site of the tumor was pancreas and diagnosis was made according to cytological and immunocytochemical analysis of the tumor cells obtained with aspiration biopsy of pancreatic mass (12 mm in diameter) under endoscopic ultrasound guidance. However, serotonin levels in blood and urine samples were normal. It is difficulty to establish the precise diagnosis of a “functionally inactive” pancreatic carcinoid and aspiration biopsy of pancreatic tumor under endoscopic ultrasound guidance can be used as a new potent diagnostic tool.

Noradrenaline represses PPAR (peroxisome-proliferator-activated receptor) gamma2 gene expression in brown adipocytes: intracellular signalling and effects on PPARgamma2 and PPARgamma1 protein levels

PPAR (peroxisome-proliferator-activated receptor) gamma is expressed in brown and white adipose tissues and is involved in the control of differentiation and proliferation. Noradrenaline stimulates brown pre-adipocyte proliferation and brown adipocyte differentiation. The aim of the present study was thus to investigate the influence of noradrenaline on PPARgamma gene expression in brown adipocytes. In primary cultures of brown adipocytes, PPARgamma2 mRNA levels were 20-fold higher than PPARgamma1 mRNA levels. PPARgamma expression occurred during both the proliferation and the differentiation phases, with the highest mRNA levels being found at the time of transition between the phases. PPARgamma2 mRNA levels were downregulated by noradrenaline treatment (EC50, 0.1 microM) in both proliferative and differentiating cells, with a lagtime of 1 h and lasting up to 4 h, after which expression gradually recovered. The down-regulation was beta-adrenoceptor-induced and intracellularly mediated via cAMP and protein kinase A; the signalling pathway did not involve phosphoinositide 3-kinase, Src, p38 mitogen-activated protein kinase or extracellular-signal-regulated kinases 1 and 2. Treatment of the cells with the protein synthesis inhibitor cycloheximide not only abolished the noradrenaline-induced down-regulation of PPARgamma2 mRNA, but also in itself induced PPARgamma2 hyperexpression. The down-regulation was probably the result of suppression of transcription. The down-regulation of PPARgamma2 mRNA resulted in similar down-regulation of PPARgamma2 and phosphoPPARgamma2 protein levels. Remarkably, the level of PPARgamma1 protein was similar to that of PPARgamma2 (despite almost no PPARgamma1 mRNA), and the down-regulation by noradrenaline demonstrated similar kinetics to that of PPARgamma2; thus PPARgamma1 was apparently translated from the PPARgamma2 template. It is suggested that beta-adrenergic stimulation via cAMP and protein kinase A represses PPARgamma gene expression, leading to reduction of PPARgamma2 mRNA levels, which is then reflected in down-regulated levels of PPARgamma2, phosphoPPARgamma2 and PPARgamma1.

Concentration of plant viruses using monolithic chromatographic supports

A new chromatographic medium, Convective Interaction Media(CIM) disk monolithic columns, was applied to plant virus concentration. The ability of the columns to concentrate highly diluted plant viruses was tested on a model plant virus, rod-shaped tomato mosaic virus (ToMV). Enzyme-linked immunosorbent assay (ELISA) was used for the quantitative analysis. The virus was concentrated using a strong anion exchanger, CIM quaternary amine (QA) disk monolithic column. A high salt concentration was used to elute the concentrated virus from the columns. It has been demonstrated that ToMV, which had been diluted considerably below the sensitivity of ELISA, was concentrated by several orders of magnitude in the one-step procedure. Concentrated virus preparations could be used directly for ELISA testing. In comparison with methods described for concentrating plant viruses from irrigation water, the above procedure may provide a much faster and more efficient way to concentrate highly diluted plant viruses. The procedure could be applied to the testing of other highly diluted plant viruses, and to concentrating viruses for antiserum production.

Retinoblastoma protein functions as a molecular switch determining white versus brown adipocyte differentiation

Adipocyte precursor cells give raise to two major cell populations with different physiological roles: white and brown adipocytes. Here we demonstrate that the retinoblastoma protein (pRB) regulates white vs. brown adipocyte differentiation. Functional inactivation of pRB in wild-type mouse embryo fibroblasts (MEFs) and white preadipocytes by expression of simian virus 40 large T antigen results in the expression of the brown fat-specific uncoupling protein 1 (UCP-1) in the adipose state. Retinoblastoma gene-deficient (Rb-/-) MEFs and stem cells, but not the corresponding wild-type cells, differentiate into adipocytes with a gene expression pattern and mitochondria content resembling brown adipose tissue. pRB-deficient MEFs exhibit an increased expression of the Forkhead transcription factor Foxc2 and its target gene cAMP-dependent protein kinase regulatory subunit RIalpha, resulting in increased cAMP sensitivity. Suppression of cAMP-dependent protein kinase activity in Rb(-/-)MEFs blocked the brown adipocyte-like gene expression pattern without affecting differentiation per se. Immunohistochemical studies revealed that pRB is present in the nuclei of white but not brown adipocyte precursor cells at a developmental stage where both cell types begin to accumulate lipid and brown adipocytes express UCP-1. Furthermore, pRB rapidly undergoes phosphorylation upon cold-induced neodifferentiation and up-regulation of UCP-1 expression in brown adipose tissue. Finally, down-regulation of pRB expression accompanies transdifferentiation of white into brown adipocytes in response to beta3-adrenergic receptor agonist treatment. We propose that pRB acts as a molecular switch determining white vs. brown adipogenesis, suggesting a previously uncharacterized function of this key cell cycle regulator in adipocyte lineage commitment and differentiation.

Radioimmunodetection of colorectal carcinoma

BACKGROUND/AIMS

The aim of the study is detection of the recurrences and metastases of colorectal carcinomas using 111In-labeled antibodies B72.3.

METHODOLOGY

Fourteen patients underwent planar immunoscintigraphy and/or tomoscintigraphy.

RESULTS

With tomography in comparison to planar scintigraphy, we can access better distinction of tumor and estimation of its size. Other imaging methods (computed tomography, ultrasonography) have an advantage in detection of liver metastases, while immunoscintigraphy is more specific for the assessment of malignant abdominal tumors and extrahepatic metastases.

CONCLUSIONS

The first results point out that Oncoscint CR-103 can be useful in diagnosis of recurrences and metastases of colorectal carcinoma, viability assessment after radiotherapy and in the choice of the adequate surgical treatment in dependence of the spread of the disease.

First Detection of Rupestris stem pitting associated virus Particles by Antibody to a Recombinant Coat Protein

Rupestris stem pitting associated virus (RSPaV), a member of the genus Foveavirus, is associated with the Rupestris stem pitting component of the Rugose wood (RW) disease complex of grapevines. Heretofore, particles of RSPaV have not been visualized. In this work, flexuous rod particles approximately 723 nm in length were detected in the sap of infected grapevines by immunosorbent electron microscopy (ISEM), using a polyclonal antiserum produced to a recombinant coat protein of RSPaV. Particles of RSPaV were detected in tissue culture-, greenhouse-, and field-grown grapevines infected with RSPaV, but not in healthy control plants. Detection of virus particles by ISEM corresponded with detection of RSPaV by Western blot, enzyme-linked immunosorbent assay, and reverse transcription-polymerase chain reaction. Virus particles were decorated with the antibodies specific to RSPaV but not with antibodies to Grapevine virus A or Grapevine virus B, two other viruses believed to be associated with RW. This definitive identification of RSPaV particles will help define the etiology of RW.

Antiserum to Recombinant Virus Coat Protein Detects Rupestris stem pitting associated virus in Grapevines

Rupestris stem pitting (RSP) is the most widespread virus disease of grapevines. The genome of Rupestris stem pitting associated virus (RSPaV), the putative causal agent of RSP, was recently sequenced. Until recently, the only method to diagnose RSP was biological indexing on woody indicator plants, a process that takes 2 to 3 years to complete. This study reports on the production of a polyclonal antiserum to a recombinant coat protein of RSPaV. The antiserum was used effectively to detect RSPaV from various genotypes and tissues of grapevines by Western blot and indirect enzyme-linked immunosorbent assay. Virus antigens were consistently detected in the cambium of dormant canes and in actively growing leaves of grapevines. Moreover, plants of Vitis rupestris 'St. George', the standard biological indicator for RSP, tested positive for RSPaV. The serological methods developed in this study are advantageous as compared with biological indexing because they are more rapid, less expensive, as reliable, and more suitable for assays of a large number of samples.

Critical roles of a cyclic AMP responsive element and an E-box in regulation of mouse renin gene expression

Mouse As4.1 cells, obtained after transgene-targeted oncogenesis to induce neoplasia in renal renin expressing cells, express high levels of renin mRNA from their endogenous Ren-1(c) gene. We have previously identified a 242-base pair enhancer (coordinates -2866 to -2625 relative to the CAP site) upstream of the mouse Ren-1(c) gene. This enhancer, in combination with the proximal promoter (-117 to +6), activates transcription nearly 2 orders of magnitude in an orientation independent fashion. To further delimit sequences necessary for transcriptional activation, renin promoter-luciferase reporter gene constructs containing selected regions of the Ren-1(c) enhancer were analyzed after transfection into As4.1 cells. These results demonstrate that several regions are required for full enhancer activity. Sequences from -2699 to -2672, which are critical for the enhancer activity, contain a cyclic AMP responsive element (CRE) and an E-box. Electrophoretic mobility shift assays demonstrated that transcription factors CREB/CREM and USF1/USF2 in As4.1 cell nuclear extracts bind to oligonucleotides containing the Ren-1(c) CRE and E-box, respectively. These two elements are capable of synergistically activating transcription from the Ren-1(c) promoter. Moreover, mutation of either the CRE or E-box results in almost complete loss of enhancer activity, suggesting the critical roles these two elements play in regulating mouse Ren-1(c) gene expression. Although the Ren-1(c) gene contains a CRE, its expression is not induced by cAMP in As4.1 cells. This appears to reflect constitutive activation of protein kinase A in As4.1 cells since treatment with the protein kinase A inhibitor, H-89, caused a significant reduction in Ren-1(c) gene expression and this reduction is mediated through the CRE at -2699 to -2688.

A simple assay for a human serum phospholipase A2 that is associated with high-density lipoproteins

Phospholipase A2 (PLA2) activity is usually assayed with expensive radioactive or chromogenic substrates unsuitable for performing large numbers of assays. We have designed a simple microplate assay for human serum PLA2 using the chromogenic substrate 4-nitro-3-octanoyloxy-benzoic acid. Using this substrate, serum PLA2 activity was similar to that measured with the previously characterized chromogenic phospholipid substrate 1,2-bis-heptanoylthio-glycerophosphocholine. However, the assay described here appears to be more sensitive. The mean PLA2 activity in serum from healthy volunteers (n = 30) measured by this assay was 10.4 +/- 1.6 micromol x h(-1) x ml(-1). The assay is reproducible and is suitable for the analysis of large numbers of samples in a clinical setting. We have also demonstrated that 94% of the PLA2 activity in normal human serum is associated with high-density lipoproteins and that serum PLA2 activity is positively correlated with the lipoprotein parameters total triglyceride (P < 0.0001), total cholesterol (P < 0.0001), and atherogenic index (P = 0.008). The serum PLA2 activity was calcium dependent and was inhibited by the serine protease inhibitor 3,4-dichloroisocoumarin (EC(50) = 0.4 mM). The PLA2 activity characterized here is unlikely to be due to plasma platelet-activating factor acetylhydrolase or low molecular weight His-Asp sPLA2, and may represent a new sPLA2 type.

Downregulation of renin gene expression by interleukin-1

The As4.1 cell line was established from a mouse kidney tumor by transgene-targeted tumorogenesis. These cells express high levels of renin mRNA from their endogenous renin gene and release approximately eightfold-more prorenin than active renin in culture. Levels of renin mRNA in As4.1 cells are decreased in a dose-dependent manner by the addition of physiological concentrations of cytokine interleukin-1 to the media. Stability of renin mRNA and initial rates of release of active renin and prorenin were not significantly altered by interleukin-1. In contrast, transcription initiated from a construct that consisted of 4.1 kilobases of renin 5' flanking sequence fused to a reporter gene (chloramphenicol acetyltransferase) was markedly inhibited by interleukin-1. On the basis of our findings, we conclude that downregulation of renin synthesis caused by interleukin-1 occurs primarily at the level of transcription and that DNA sequence or sequences mediating that effect are positioned within 4.1 kilobases upstream of the renin gene. The physiological relevance of this regulation is related to the events that occur during septic shock, characterized by hypotension, cardiovascular collapse, multiple organ failure, and high mortality. Unexpectedly, hypotension associated with septic shock does not lead to activation of the renin-angiotensin system. The hypotension in septicemia is believed to be mediated by the combined action of many modulators including cytokines, and data presented here suggest direct involvement of interleukin-1 in this process.

Biosynthesis of renin in mouse kidney tumor As4.1 cells

As4.1, a renin-expressing cell line isolated from a mouse renal tumor, was characterized for synthesis, processing, storage and secretion of renin polypeptides. Metabolic labeling, immunoprecipitation and SDS/PAGE analysis revealed that renin was secreted into the culture supernatant predominantly in the form of prorenin which migrated as products of 42-47 kDa. The predominant intracellular renin was processed into two chains, of 33-34 and 5 kDa. N-glycanase treatment removed N-linked oligosaccharides and yielded products of 41 kDa for prorenin and 31-32 kDa for the heavier chain of two-chain renin. The N-terminus of the constitutively secreted prorenin was determined by automated Edman degradation to be Leu22 while the N-terminus of the heavy chain was Ser72. Renin polypeptides constituted 3.1 +/- 1.4% (mean percentage of total precipitable radioactivity +/- SD) of de-novo-synthesized protein secreted into the medium and 0.2 +/- 0.17% retained intracellularly. Extrapolation of renin activity assays suggest that a single cell stores approximately 680 fg of active renin. A slow incremental release into the medium of processed renin heavy chain was detected by immunoprecipitation and SDS/PAGE. Renin activity assays confirmed the release of approximately 4 fg prorenin and 0.32 fg active renin cell(-1) h(-1). Indirect immunofluorescence demonstrated intracellular renin to be distributed in a punctate pattern. Renin was found to be colocalized with the lysosomal marker, beta-glucuronidase, by double-fluorescent labeling. These cells have enabled characterization of glycosylated mouse renin-1 and may prove a valuable tool for studying intracellular trafficing of renin and associated processing enzymes.

Identification of an apo-superoxide dismutase (Cu,Zn) pool in human lymphoblasts

Copper incorporation (64Cu(II)) into Cu,Zn-superoxide dismutase (SOD) was studied in human lymphoblasts. Rapid incorporation of copper with a proportionate increase in SOD activity was detected. No copper incorporation or SOD activation was detected when 64Cu(II) was added to cell cytosols rather than to intact cells. Thus, incorporation of 64Cu was not due to isotopic exchange. Cycloheximide had no significant effect on copper incorporation and activation of SOD when the data were corrected for total cell copper. Thus, the data were consistent with copper incorporation into a preexisting apoSOD pool rather than newly synthesized SOD, and no new SOD synthesis was detected over a 15-h incubation period. The size of the apoSOD pool was estimated to be approximately 35% of the total SOD in lymphoblasts. When cells were preincubated for 15 h with excess copper (15 microM Cu(II)), the size of the apo pool markedly decreased but was not eliminated, suggesting that the apoSOD was not due to copper deficiency. These experiments also indicated that newly arrived copper was preferentially incorporated into the apoSOD pool, while the function(s) of an apoSOD pool remains unknown. Copper binding to apoSOD may provide a rapid protective response against copper toxicity.

Copper incorporation into superoxide dismutase in Menkes lymphoblasts

The incorporation of copper into Cu,Zn-superoxide dismutase (SOD) was examined in Menkes lymphoblasts that express a genetic defect of copper metabolism. SOD activity was approximately 40% higher in Menkes than normal lymphoblasts. Since Menkes lymphoblasts contain elevated copper levels, the higher SOD activity is most likely due to near copper saturation of an apoSOD pool that is in normal lymphoblasts. Cycloheximide markedly inhibited 64Cu(II) incorporation into SOD in Menkes lymphoblasts under conditions in which no significant, de novo synthesis of SOD protein was detected with normal lymphoblasts. The maximal amount of 64Cu incorporation into newly synthesized SOD in Menkes lymphoblasts was approximately equal to the maximal amount of 64Cu that could be incorporated into the apoSOD pool in normal lymphoblasts. The increased synthesis of SOD in Menkes lymphoblasts may play a protective role against copper toxicity in Menkes lymphoblasts. The protonophore, CCCP markedly inhibited 64Cu incorporation into SOD in both normal and Menkes lymphoblasts, which is consistent with 64Cu incorporation into SOD within a membrane-bounded compartment in both cell types. When 64Cu-incorporation into SOD was blocked with CCCP, copper accumulated in a Superose column fraction that contains S-adenosylhomocysteine hydrolase (SAHH), which has a high affinity for copper. SAHH may play a role in delivering copper to SOD.

Role of proximal promoter elements in regulation of renin gene transcription

Mouse As4.1 cells, obtained after transgene-targeted oncogenesis to induce neoplasia in renal renin-expressing cells, express high levels of renin mRNA from the endogenous Ren-1(c) gene. We have used these cells to characterize the role of the Ren-1(c) proximal promoter (+6 to -117) in the regulation of renin gene transcription. It was found that 4.1 kilobases (kb) of Ren-1(c) 5'-flanking sequence, in combination with the proximal promoter, are required for strong activation (approximately 2 orders of magnitude over the basal level of the promoter alone) of the chloramphenicol acetyltransferase reporter in transfection assays. Within the 4.1-kb fragment, a 241-base pair region was identified that retains full activity in an orientation-independent manner in combination with the promoter. The resulting transcripts initiate at the normal renin start site. Electrophoretic mobility shift assays identified a sequence at approximately position -60 in the promoter region that binds nuclear proteins specific for renin-expressing As4.1 cells. Mutations in this sequence, which disrupt binding of nuclear protein(s), completely abolish activation of transcription by the 4. 1-kb fragment. Activation of transcription by the 241-base pair enhancer was still observed, although it was diminished in magnitude (60-fold over the mutated promoter alone). We present a model derived from the current data that suggests that regulation of renin expression is achieved through cooperation of transcription factors binding at the proximal promoter element and a distal enhancer element to abrogate or override the effects of an intervening negative regulatory region.

Identification of a major hepatic copper binding protein as S-adenosylhomocysteine hydrolase

The properties of a mouse liver copper binding protein (CuBP) and human placental S-adenosylhomocysteine hydrolase (SAHH) were compared to test the hypothesis that CuBP is SAHH. CuBP and SAHH migrated identically on SDS-polyacrylamide gel electrophoresis gels, and their 48-kDa monomers both self-associate to tetramers. Human placental SAHH cross-reacted with polyclonal antibodies to mouse liver CuBP, and CuBP from mouse liver cross-reacted with two monoclonal antibodies to human placental SAHH. A third monoclonal antibody to human placenta SAHH reacted weakly with the mouse liver protein but well with CuBP from human lymphoblasts. NAD(+)-activated CuBP has high SAHH enzymatic activity. Moreover, human placental SAHH, like mouse liver CuBP, has a single high affinity copper binding site per 48-kDa subunit. Thus, the data confirm that CuBP is SAHH, and SAHH is proposed to be a bifunctional protein with roles in sulfur-amino acid metabolism and copper metabolism. The copper binding activity of SAHH is proposed to play a significant role in the intracellular distribution of copper, and SAHH enzymatic activity may influence copper metabolism through its role in cysteine biosynthesis from methionine.

[Treatment using Motilium of gastro-esophageal reflux associated with respiratory manifestations in children]

Eighteen children aged 1 month to 12 years 8 months (mean age, 4.9 years) with pH-metry proven gastroesophageal reflux (GOR)-associated chronic respiratory disorders were treated with Motilium, 2 mg/kg/d in four divided doses, for three months. The incidence of each of the respiratory manifestations decreased, and their cumulative score improved significantly at the end of the treatment period. Patient daily self-assessment scores also fell, but not significantly. Twenty-one hour pH recordings showed a significant reduction in the duration of nocturnal episodes below 4 (2.8 +/- 0.9% versus 8.2 +/- 2.6%, p less than 0.05). No side effects were recorded. Domperidone provides satisfactory control of nocturnal GOR and therefore emerges as a valuable agent for the treatment of chronic GOR-associated respiratory disorders in childhood.