[26-year-old patient with ulcerative colitis and anemia]

A 26-year-old patient was admitted to the hospital because of severe anemia and exacerbation of ulcerative colitis. Laboratory tests revealed a hemolytic anemia and elevated parameters of acute phase reaction. Ten months ago an autoimmune hemolytic anemia was diagnosed. Three months before admission splenectomy was performed due to ongoing hemolytic exacerbations despite treatment with corticosteroids. Anemia is a common problem of inflammatory bowel disease. The association of autoimmune hemolytic anemia and ulcerative colitis presented in this case report is a rare complication of ulcerative colitis. The autoimmune hemolytic anemia is often refractory to corticosteroids. Immunosuppressive treatment with azathioprine induced a sustained remission in our patient, thereby a total colectomy could be avoided.

No association between the angiotensin-converting-enzyme gene insertion/deletion polymorphism and the occurrence of macroangiopathy in patients with diabetes mellitus type 2

Previous studies have reported an association between the ACE-I/D-polymorphism and coronary heart disease (CHD) in patients with diabetes mellitus. However, ACE inhibitor treatment, which could have compensated for negative effects of the D/D form of the ACE gene polymorphism, was not considered in the studies. We investigated the influence of the ACE-I/D polymorphism and the ACE inhibitor treatment in patients with diabetes mellitus on the occurrence of CHD by multiple-regression analysis. Distribution of the ACE gene I/D-polymorphism was investigated in 691 patients with diabetes mellitus prospectively characterised for the presence/absence of coronary heart disease. The distribution of DD; ID; II genotypes was 105 vs. 202 vs. 102 (25.7 % vs. 49.4 % vs. 24.9) in the CHD + group and 55 vs. 160 vs. 67 (19.5 % vs. 56.7 % vs. 23.8 %) in the CHD - group, respectively (p = 0.1). A multiple logistic regression analysis introducing the typical risk factors for CHD (age, gender, smoking, BMI > 26 kg/m 2, LDL elevation, HbA1c > 7 %) could not identify the ACE gene I/D-polymorphism as an independent risk factor for CHD (p = 0.87). Our data therefore suggest that the ACE gene I/D polymorphism is not associated with the occurrence of diabetic macroangiopathy in patients with or without treatment of ACE inhibitors.

An alternative mechanism for amidase signature enzymes

The peptide amidase from Stenotrophomonas maltophilia catalyses predominantly the hydrolysis of the C-terminal amide bond in peptide amides. Peptide bonds or amide functions in amino acid side-chains are not hydrolysed. This specificity makes peptide amidase (Pam) interesting for different biotechnological applications. Pam belongs to the amidase signature (AS) family. It is the first protein within this family whose tertiary structure has been solved. The structure of the native Pam has been determined with a resolution of 1.4A and in complex with the competitive inhibitor chymostatin at a resolution of 1.8A. Chymostatin, which forms acyl adducts with many serine proteases, binds non-covalently to this enzyme.Pam folds as a very compact single-domain protein. The AS sequence represents a core domain that is covered by alpha-helices. This AS domain contains the catalytic residues. It is topologically homologous to the phosphoinositol phosphatase domain. The structural data do not support the recently proposed Ser-Lys catalytic dyad mechanism for AS enzymes. Our results are in agreement with the role of Ser226 as the primary nucleophile but differ concerning the roles of Ser202 and Lys123: Ser202, with direct contact both to the substrate molecule and to Ser226, presumably serves as an acid/bases catalyst. Lys123, with direct contact to Ser202 but no contact to Ser226 or the substrate molecule, most likely acts as an acid catalyst.

Synaptic ribbon dynamics in photoreceptors of mice

The present study deals with structural plasticity of a special type of chemical synapse, the ribbon synapse. Near the presynaptic membrane ribbon synapses contain conspicuous electron-dense synaptic bodies which appear mainly as rod-like profiles under the transmission electron microscope. In addition, club-shaped and spherical profiles may be present, the function of which is unclear. To gain some insight into the significance of the latter structures we studied their presence in rod-type photoreceptor cells of BALB/c mice under different lighting conditions. Quantification revealed that the club-shaped and the spherical profiles showed a clear light/dark dependence. They were virtually absent at night and increased strikingly in number when the animals were exposed to light. When darkness was extended into the morning, the profiles remained low in number. As the rod cells diminish their neurotransmitter release during the light phase, the present findings are interpreted as signs of synapse inactivation.

Gene cloning, overexpression and biochemical characterization of the peptide amidase from Stenotrophomonas maltophilia

The peptide amidase (Pam) from the gram-negative bacterium Stenotrophomonas maltophilia catalyzes predominantly the hydrolysis of the C-terminal amide bond in peptide amides. Its gene ( pam) was isolated by Southern hybridization using a DNA probe derived from the known N-terminal amino acid sequence. Pam is a member of the amidase signature family and was identified as a periplasmic protein by an N-terminal signal peptide found in the gene. The processed protein consists of 503 amino acids with a molecular mass of 53.5 kDa. The recombinant enzyme with a C-terminal His(6) tag has a monomeric structure and its isoelectric point is 6.3. The dipeptide amide L-Ala- L-Phe-NH(2) is hydrolyzed in the absence of cofactors to L-Ala- L-Phe-OH and ammonia with V(max)=194 U/mg and K(m) <0.5 mM. The natural function of Pam remains unclear. Chymostatin ( K(i)<0.3 microM) and Pefabloc SC ( K(i) not determined) were identified as inhibitors. When the gene was expressed in Escherichia coli on a 12-l scale, the specific activity in the crude extract was 60 U/mg, compared to 0.24 U/mg in S. maltophilia. In the expression system, Pam made up about 31% of the total soluble cell protein. From 75 g wet cells, 2.1 g of >95% pure enzyme was obtained, which corresponds to a total activity of 416,000 units.

Characterization and chromosome assignment of the canine gamma-sarcoglycan gene (SGCG) to CFA 25q21-->q23

Mutations in the gene for gamma-sarcoglycan (SGCG) located on HSA 13q12 are responsible for limb girdle muscular dystrophy (LGMD2C) in human. Here we report the cloning of the canine SGCG gene together with its genomic structure and several intragenic polymorphisms. The coding part of the canine SGCG contains seven exons spanning at least 70 kb of genomic DNA. The chromosome assignment of the canine SGCG gene to CFA 25q21-->q23 confirms that the canine syntenic group 10 corresponds to CFA 25 and also supports the findings of human-canine reciprocal chromosome painting.

Crystallization and preliminary X-ray data of the recombinant peptide amidase from Stenotrophomonas maltophilia

The peptide amidase from Stenotrophomonas maltophilia selectively hydrolyses the C-terminal amide bond in peptide amides. Crystals have been obtained by sitting-drop vapour diffusion from solution containing polyethylene glycol (PEG) 6000, HEPES pH 7.5, glycerine and sodium azide (NaN(3)). The crystals belong to the monoclinic space group P2(1), with unit-cell parameters a = 74.18, b = 62.60, c = 101.91 A, beta = 90 degrees. X-ray data from these crystals diffracted at the European Synchrotron Radiation Facility (ESRF, France) ID14-1 beamline to 1.4 A.

Sodium/iodide symporter mRNA expression in cold thyroid nodules

Clinical and experimental data suggest a low thyroid hormone synthesis in cold thyroid nodules (CTN). Therefore, the Na(+)/I(-)-symporter (NIS) as the first step in the thyroid hormone synthesis could be a possible candidate gene in the pathogenesis of CTNs. A reduction of NIS transcripts in CTNs compared to samples of normal thyroid tissues with large inter-individual variations ranging from 2- to 700-fold reductions was observed with real-time RT-PCR. Therefore, the aim of our investigations was to perform an intra-individual comparison of NIS expression in CTNs. Moreover, we used direct detection of NIS mRNA by RNase protection assay (RPA). We investigated 14 patients with one CTN for NIS mRNA expression. NIS mRNA transcripts from nodule and surrounding tissue were examined by RPA. A significantly reduced NIS expression was detected in 86% of the CTNs compared to their corresponding surrounding tissue. The level of NIS expression was decreased to more than 65% in 10 CTNs (72% of the nodules). Two of the 14 nodules showed a decrease of NIS mRNA expression of 42%, and 32%, while no significant differences could be detected in 2 cold nodules. Compared to other studies the intra-individual comparison of NIS mRNA expression revealed a much lower variation of reduced NIS expression in CTNs. Further studies should try to identify molecular factors like post-transcriptional modifications or alterations in iodide organification which are likely to be involved in the pathogenesis of CTNs.

Adrenocorticotrope deficiency with clinical evidence for late onset in combined pituitary hormone deficiency caused by a homozygous 301-302delAG mutation of the PROP1 gene

Combined pituitary hormone deficiency (CPHD) can be caused by mutation of the pituitary transcription factors POU1F1 or PROP1. More recently mutations in the HESX1, the LHX3 and LHX4 transcription factor genes have also been described as a cause in patients with CPHD. In most patients the disorder is characterized by an impaired production of GH, TSH, PRL and gonadotropins. In some cases of CPHD adrenocorticotropin deficiency is also present. We report the progressive CPHD and its molecular etiology in a woman with CPHD presenting with first symptoms of ACTH/cortisol deficiency at the age of 48 years. The 49 year old patient's initial symptoms were growth retardation at the age of 2 years and symptoms of hypothyroidism at the age of 5 years. The patient never entered puberty spontaneously. No familial history of delayed puberty, growth retardation or other symptoms of CPHD were present. At the age of 48 years the patient presented with the first symptoms of hypocortisolism such as recurring hypoglycaemias and hyponatriaemia with coma. Cortisol, ACTH, TSH, fT3, fT4 and GH as well as LH, FSH and PRL were measured in basal conditions. GH, cortisol and ACTH were also measured in response to an Insulin Tolerance Test. Molecular analysis was performed by PCR amplification and sequencing of exon 1-3 of the PROP1 gene. The patient had insufficiencies of TSH, LH, FSH and GH. PRL was normal. Serum cortisol was low and basal ACTH was normal. However, there were no responses of cortisol, ACTH and GH to hypoglycaemia. Magnetic resonance imaging showed a hypoplastic anterior pituitary lobe. Direct sequencing revealed a homozygous 2 base-pair deletion 301-302delAG in exon 2 of the PROP1 gene. This case suggests that in patients with CPHD ACTH producing cells may be involved at a rather late age.

Thyrotropin receptor mutations as a tool to understand thyrotropin receptor action

A large number of mutations have been identified in the thyrotropin (TSH) receptor (TSHR) gene causing human diseases. Toxic thyroid nodules are frequently associated with somatic constitutively activating TSHR mutations. Autosomal dominant non-autoimmune hyperthyroidism is caused by activating TSHR germline mutations. Inactivating germline mutations cause TSH unresponsiveness. Discovery of the different TSHR mutations in various regions of the receptor molecule has led to the identification of important domains for intramolecular TSHR signal transduction. However, despite the functional characterization of the naturally occurring mutations the precise molecular mechanisms of receptor activation including the processes of hormone binding, intramolecular signaling between the different TSHR domains and of G protein coupling are not completely understood. This review discusses the importance of the various receptor domains for TSHR activation identified on the basis of the naturally occurring gain or loss of function mutations and in vitro investigations performed with site-directed mutagenesis, synthetic peptides, or antibodies. Several in vitro studies have provided new insights into structure-function relationships by site-directed mutagenesis in combination with molecular modeling. These in vitro investigations have often been guided by naturally occurring mutations and have provided new insights into intramolecular changes during receptor activation. This has led to progress in understanding the mechanism of TSHR activation.

Tumor necrosis factor alpha is a negative regulator of resistin gene expression and secretion in 3T3-L1 adipocytes

Resistin has recently been implicated as an adipocytokine leading to insulin resistance and, therefore, potentially linking obesity and diabetes. To further characterize the regulation of this fat-secreted protein by insulin sensitivity-modulating hormones, 3T3-L1 adipocytes were treated with tumor necrosis factor (TNF) alpha, angiotensin (AT) 2, as well as growth hormone (GH), and resistin gene expression and protein secretion were determined by quantitative real-time reverse transcription-polymerase chain reaction and Western blotting. Interestingly, both, resistin mRNA expression and protein secretion, were inhibited by 70-90% after TNFalpha-treatment whereas AT2 and GH did not have any effect. The inhibitory effect of TNFalpha was time- and dose-dependent with significant inhibition occurring as early as 4 h after effector addition and at concentrations as low as 1 ng/ml TNFalpha. Pharmacological inhibition of protein kinase A (PKA), p44/42, and p38 mitogen-activated protein (MAP) kinase did not reverse the inhibitory effect of TNFalpha suggesting that neither of these signaling molecules is involved in suppression of resistin gene expression by TNFalpha. Furthermore, suppression of resistin mRNA levels could be completely reversed to control levels by withdrawal of TNFalpha for 24 h. Taken together, these results suggest that TNFalpha is a pivotal negative regulator of resistin gene expression. This may have important implications for the pathogenesis of insulin resistance and its link to obesity.

Prevalence of cystic fibrosis mutations in Israeli Jews

The aim of this study was to evaluate the screening policies of cystic fibrosis (CF) in the Jewish population. The prevalence of mutations that account for CF in Israel have been defined in the past by determining the frequency of CF mutations in affected individuals. This study is a population-based study and is, therefore, different from previous patient-based studies. We found that the CF mutations D1152H, W1089X, and 405 + IG-->A were present in some ethnic groups in which no CF patients carrying these mutations were reported. These facts necessitate a reevaluation of the screening policy regarding the ethnic groups in Israel. We studied 9,430 healthy Jewish Israeli individuals of 36 countries of origin. The prevalence of CF mutations was 1:19, 1:19, 1:28, and 1:42 for the Ashkenazi, Sephardi, North African, and Eastern Jews, respectively. CF mutations were identified in 374 (4.0%) individuals. These included 173 (46.3%) carriers of the W1282X mutation; 110 (29.4%) found to carry delF508; 23 (6.1%) who carried G542X; 22 (5.9%) who carried 3849 + 10Kb (C-->T; 20 (5.3%) who carried D1152H; 10 (2.7%) who carried N1303K; 11 (2.9%) who carried 405 + IG-->A; 4 (1.1%) who carried W1089X; and one (0.3%) who carried S549R. No carriers were detected for the 1717-1G-->A, G85E, and T360K mutations, which were tested for in 7,383, 1,558, and 41 individuals, respectively.

Identification of new mutations in Israeli patients with X-linked adrenoleukodystrophy

X-linked adrenoleukodystrophy (ALD) is a peroxisomal disorder characterized by impaired peroxisomal betaoxidation of very-long-chain fatty acids (VLCFAs). This is probably due to reduced activation of the VLCFAs and results in demyelination of the nervous system and adrenocortical insufficiency. The ALD gene is localized on Xq28, has 10 exons and encodes a protein of 745 amino acids with significant homology to the membrane peroxisomal protein PMP70. Characterizing the disease causing mutations is of importance in prenatal diagnosis because 12-20% of women who are obligatory carriers show false-negative results when tested for VLCFA in plasma. We have analyzed DNA from blood samples of 7 Jewish (5 Sephardi and 2 Ashkenazi) and 3 Arab Israeli families suffering from ALD. Five missense-type mutations were identified: R104H, Y174C, L229P, R401Q, and G512C. A single mutation, R464X, was nonsense, and two, Y171 frameshift and E471 frameshift, were frameshift. Interestingly, a single mutation was identified in three families of Moroccan Jewish descent, probably due to a founder effect.

Adiponectin gene expression is inhibited by beta-adrenergic stimulation via protein kinase A in 3T3-L1 adipocytes

Recently, it has been shown that the fat-derived factor adiponectin is downregulated in insulin resistance and obesity and that replenishment of this adipocytokine reverses insulin resistance in mice. Growing evidence, on the other hand, suggests that raised levels of catecholamines due to increased activity of the sympathetic nervous system are an integral part in the development of insulin resistance. To clarify whether catecholamines might exert their insulin resistance-inducing effects at least partly via downregulation of adiponectin gene expression, 3T3-L1 adipocytes were treated with isoproterenol, and adiponectin mRNA was measured by quantitative real-time reverse transcription-polymerase chain reaction. In fact, isoproterenol treatment reduced the level of adiponectin mRNA by about 75% in a dose-dependent fashion with significant inhibition detectable at concentrations as low as 10 nM isoproterenol. Furthermore, the inhibitory effect of isoproterenol was almost completely reversed by pretreatment of 3T3-L1 cells with the beta-adrenergic antagonist propranolol and the protein kinase A (PKA) inhibitor H-89. Moreover, the effects of isoproterenol could be mimicked by stimulation of stimulatory guanine nucleotide-binding (G(S))-proteins with cholera toxin and adenylyl cyclase with forskolin. Thus, our results suggest that adiponectin gene expression is severely suppressed by beta-adrenergic agents via activation of a G(S)-protein-PKA-dependent pathway. The data support a possible role of adiponectin in catecholamine-induced insulin resistance.

Search for mitochondrial DNA mutation at position 3243 in German patients with a positive family history of maternal diabetes mellitus

Mitochondrial diabetes is one of the most common monogenetic forms of diabetes mellitus. However, variable prevalences have been reported by different investigators. Therefore, the aim of our study was to investigate the prevalence of the most prevalent mitochondrial DNA mutation at position 3243 (A --> G) in german patients with a positive family history of maternally inherited diabetes mellitus and/or hearing loss. We screened 1460 patients with diabetes mellitus by a questionnaire and identified 122 patients with a positive family history of maternal diabetes mellitus. Seven of the 122 patients suffered from hearing loss in addition. An EDTA blood sample of each patient was examined by polymerase chain reaction followed by a digestion with Bsp120I. In addition all samples were further examined by denaturing gradient gel electrophoresis to increase the detection limit for heteroplasmy. Only one mt DNA mutation at position 3243 could be detected in the 122 patients. The detection limit of denaturing gradient gel electrophoresis (DGGE) for heteroplasmy was 3%. We detected one new polymorphism at position 3333 (C --> T) of the mitochondrial genome (0.8% of the patients), and a known polymorphism at position 3197 (T --> C) in 10.6% of the patients. We therefore conclude that the frequency of the A3243G mutation is much lower in the investigated study population, mostly originating from Saxonia, than in asian populations.

A free carboxylate oxygen in the side chain of position 674 in transmembrane domain 7 is necessary for TSH receptor activation

A specific H-bonding network formed between the central regions of transmembrane domain 6 and transmembrane domain 7 has been proposed to be critical for stabilizing the inactive state of glycoprotein hormone receptors. Many different constitutively activating TSH receptor point mutations have been identified in hyperfunctioning thyroid adenomas in the lower portion of transmembrane domain 6. Position D633 in transmembrane domain 6 of the human TSH receptor is the only one in which four different constitutively activating amino acid exchanges have been identified. Further in vitro substitutions led to constitutive activation of the TSH receptor (D633Y, F, C) as well as to the first inactivating TSH receptor mutation in transmembrane domain 6 without changes of membrane expression or TSH binding (D633R). Molecular modeling of this inactivating TSH receptor mutation revealed potential interaction partners of R633 in transmembrane domain 3 and/or transmembrane domain 7, presumably via hydrogen bonds that could be responsible for locking the TSH receptor in a completely inactive state. To further elucidate the H-bond network that most likely maintains the inactive state of the TSH receptor, we investigated these potential interactions by generating TSH receptor double mutants designed to break up possible H bonds. We excluded S508 in transmembrane domain 3 as a possible interaction partner of R633. In contrast, a partial response to TSH stimulation was rescued in a receptor construct with the double-substitution D633R/N674D. Our results therefore confirm the H bond between position 633 in transmembrane domain 6 and 674 in transmembrane domain 7 suggested by molecular modeling of the inactivating mutation D633R. Moreover, the mutagenesis results, together with a three-dimensional structure model, indicate that for TSH receptor activation and G protein-coupled signaling, at least one free available carboxylate oxygen is required as a hydrogen acceptor atom at position 674 in transmembrane domain 7.

Isoproterenol inhibits resistin gene expression through a G(S)-protein-coupled pathway in 3T3-L1 adipocytes

Resistin was recently identified as a hormone secreted by adipocytes which leads to insulin resistance in vivo and in vitro and might therefore be an important link between obesity and diabetes. To clarify the regulation of resistin gene expression, 3T3-L1 adipocytes were treated with various agents known to modulate insulin sensitivity, and resistin mRNA was measured by quantitative real-time reverse transcription-polymerase chain reaction. Interestingly, isoproterenol treatment reduced the level of resistin mRNA to 20% of non-treated control cells. This effect was dose-dependent with significant inhibition occurring at concentrations as low as 10 nM isoproterenol. Moreover, pretreatment of adipocytes with the beta-adrenergic antagonist propranolol almost completely reversed the inhibitory effect of isoproterenol, whereas addition of the alpha-adrenergic antagonist phentolamine did not have any effect. Furthermore, the effect of isoproterenol could be mimicked by activation of G(S)-proteins and adenylyl cyclase. Thus, both cholera toxin and forskolin decreased resistin mRNA expression in a dose-dependent fashion by up to 90% of control levels. Taken together, these results suggest that resistin gene expression is regulated by a protein kinase A-dependent pathway in 3T3-L1 adipocytes.

Mutations in the mouse TSH receptor equivalent to human constitutively activating TSH receptor mutations also cause constitutive activity

Constitutively activating mutations in the human thyroid-stimulating hormone (TSH) receptor (TSHr) have been identified as the most prevalent molecular cause of non-autoimmune hyperthyroidism. To investigate the feasibility of an animal model for non-autoimmune hyperthyroidism, we introduced two mutations in the mouse TSHr which had previously been identified in the human TSHr. The two human mutations showed strong differences in TSH binding, basal cAMP and IP accumulation. In the human TSHr, the Ile 486 Phe mutation causes a high increase of basal cAMP accumulation and also basal stimulation of the inositol phosphate pathway, whereas the Val 509 Ala mutation results in a low increase of basal cAMP accumulation without affecting IP signaling. RNA was isolated from mouse thyroid tissue and reverse transcribed. A 2.4 kb PCR product from the mouse TSHr was cloned into the pGEM-T vector system. Ile was substituted with Phe at codon 486 and Val with Ala at codon 509. These mutated mouse TSHrs were subcloned in the pSVL expression vector. After transient expression in COS-7 cells, basal and TSH-stimulated cAMP and IP accumulation, cell surface expression and TSH binding were determined and directly compared to the human TSHr. Whereas constitutively activating mutations of the human parathyroid hormone (PTH)/PTH-related peptide receptor showed little or no change in basal cAMP accumulation when introduced into the rat PTH/PTHrP receptor, these two mouse TSHr mutations resulted in constitutive activity similar to the homologous mutations in the human TSHr. Therefore, it should be possible to establish a mouse model for non-autoimmune hyperthyroidism by homologous recombination to study the pathogenetic mechanisms of non-autoimmune hyperthyroidism.

A small dose of droperidol decreases postoperative nausea and vomiting in adults but cannot improve an already excellent patient satisfaction

BACKGROUND

We evaluated whether or not 1) a routine prophylaxis with 20 microg x kg(-1) body weight of droperidol would efficiently prevent postoperative nausea and vomiting (PONV) after elective surgery in adults and 2) an efficient prophylaxis would improve patient satisfaction.

METHODS

With approval of the local ethics committe and after having obtained informed written consent, 1334 patients in a randomised, single-blinded fashion either received droperidol (group 1, n=665) or saline intravenously (group 2, n=669) 20 min before the end of a standard O2/N2O/fentanyl/isoflurane anaesthesia of at least 30 min duration.

END POINTS

incidence of PONV during the first 24 h; individual episodes of nausea or vomiting, overall patient satisfaction with the procedure.

RESULTS

Compared to saline, intravenous injection of droperidol substantially and significantly reduced the incidence of PONV from 30% to 20% (P<0.0001). Women suffered three times more frequently from PONV (10.5% vs. 30%, P<0.0001). Droperidol significantly reduced the incidence of PONV from 35.4% to 24.4% in women (relative risk reduction: 31%, P=0.0002), but not in men (13.1% vs. 8.2%, relative risk reduction: 37%, P=0.159)--without impact on overall patient satisfaction (98.8% vs. 97.1%, P=0.439). Distribution of surgical procedures, sex, age, height, weight and anaesthetic duration were not different between groups. To prevent one woman from suffering PONV, nine had to be treated prophylactically at an individual drug cost (German prices) of about Euro0.80 per woman.

CONCLUSION

Routine PONV prophylaxis with 20 microg x kg(-1) body weight of droperidol is cost-efficient and appropriate in women but not in men.

Macromolecular trafficking between Nicotiana tabacum and the holoparasite Cuscuta reflexa

Transgenic tobacco plants expressing green fluorescent protein (GFP) under the control of the companion cell-specific promoter, AtSUC2, were parasitized by the holoparasite Cuscuta reflexa (dodder). GFP, moving in the translocation stream of the host, was transferred to the Cuscuta phloem via the absorbing hyphae of the parasite. An identical pattern of transfer was observed for the phloem-mobile probe, carboxyfluorescein. Following uptake by the parasite, GFP was translocated and unloaded from the Cuscuta phloem in meristematic sink tissues. Contrary to published data, these observations suggest the presence of a functional symplastic pathway between Cuscuta and its hosts, and demonstrate a considerable capacity for macromolecular exchange between plant species.

Macromolecular trafficking between Nicotiana tabacum and the holoparasite Cuscuta reflexa

Transgenic tobacco plants expressing green fluorescent protein (GFP) under the control of the companion cell-specific promoter, AtSUC2, were parasitized by the holoparasite Cuscuta reflexa (dodder). GFP, moving in the translocation stream of the host, was transferred to the Cuscuta phloem via the absorbing hyphae of the parasite. An identical pattern of transfer was observed for the phloem-mobile probe, carboxyfluorescein. Following uptake by the parasite, GFP was translocated and unloaded from the Cuscuta phloem in meristematic sink tissues. Contrary to published data, these observations suggest the presence of a functional symplastic pathway between Cuscuta and its hosts, and demonstrate a considerable capacity for macromolecular exchange between plant species.

Genomic organization of the dog dystroglycan gene DAG1 locus on chromosome 20q15.1-q15.2

Dystroglycan is a laminin binding protein, which provides a structural link between the subsarcolemmal cytoskeleton and the extracellular matrix. It is also involved in the organization of basement membranes. So far the genomic organization of the dystroglycan gene DAG1 has not been completely investigated. Here we report the cloning and sequencing of 162 kb of dog genomic DNA containing the complete approximately 71-kb canine DAG1 gene, which consists of three exons, with the translation start codon located in exon 2. Its 2679-nucleotide ORF encodes a polypeptide of 892 amino acids, which is highly similar to human, rabbit, and bovine orthologs. To further characterize the dog DAG1 gene we determined the transcription start site and several naturally occurring polymorphisms, which partially result in amino acid substitutions of the dystroglycan protein. The dog DAG1 gene was assigned to chromosome 20q15.1-q15.2 by FISH analysis. The analysis of the entire reported sequence revealed that the genes for aminomethyltransferase (AMT), bassoon (BSN), TCTA (T-cell leukemia translocation-associated) gene, and an as yet uncharacterized protein are located very close to the DAG1 gene. Therefore, this study defines a novel syntenic region among dog chromosome 20q15, human chromosome 3p21, and murine chromosome 9F.

Characterization of the cys gene locus from Allochromatium vinosum indicates an unusual sulfate assimilation pathway

Homologues of the genes cysB, cysI, cysH, cysD, cysN, and selD were identified in the genome of the phototrophic purple sulfur bacterium Allochromatium vinosum (formerly Chromatium vinosum). On the basis of amino acid comparisons these genes encode a ferredoxin-dependent siroheme-sulfite reductase (CysI), a plant-type assimilatory APS reductase without thioredoxin domain (CysH), the two different subunits of heterodimeric ATP sulfurylase (CysDN), a transcriptional regulator (CysB) and a selenophosphate synthase (SelD). cysIHDN appear to form an operon and are preceded by cysB which is transcribed in the opposite direction. SelD is situated downstream of cysN and transcribed divergently to cysIHDN. The lack of a gene for APS kinase and presence of a gene for an assimilatory APS reductase implies that assimilatory sulfate reduction in A. vinosum proceeds along the pathway suggested for higher plants without intermediary formation of PAPS. Two completely separate pathways involving specialized enzymes are used for assimilatory sulfate reduction and dissimilatory sulfur oxidation in A. vinosum. The presence of cysB indicates that the genes for assimilatory sulfate reduction are expressed only in the absence of reduced sulfur compounds.

Sequence and analysis of chromosome 4 of the plant Arabidopsis thaliana

The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the sequence of chromosome 4. Analysis of 17.38 megabases of unique sequence, representing about 17% of the genome, reveals 3,744 protein coding genes, 81 transfer RNAs and numerous repeat elements. Heterochromatic regions surrounding the putative centromere, which has not yet been completely sequenced, are characterized by an increased frequency of a variety of repeats, new repeats, reduced recombination, lowered gene density and lowered gene expression. Roughly 60% of the predicted protein-coding genes have been functionally characterized on the basis of their homology to known genes. Many genes encode predicted proteins that are homologous to human and Caenorhabditis elegans proteins.

Linkage of familial euthyroid goiter to the multinodular goiter-1 locus and exclusion of the candidate genes thyroglobulin, thyroperoxidase, and Na+/I- symporter

Iodine deficiency is the most important etiological factor for euthyroid endemic goiter. However, family and twin pair studies also indicate a genetic predisposition for euthyroid simple goiter. In hypothyroid goiters several molecular defects in the thyroglobulin (TG), thyroperoxidase (TPO), and Na+/I- symporter (NIS) genes have been identified. The TSH receptor with its central role for thyroid function and growth is also a strong candidate gene. Therefore, we investigated a proposita with a relapsing euthyroid goiter and her family, in which several members underwent thyroidectomy for euthyroid goiter. Sequence analysis of the complementary DNA (cDNA) of the TPO and TSH receptor genes revealed several previously reported polymorphisms. As it is not possible to exclude a functional relevance for all polymorphisms, we opted for linkage analysis with microsatellite markers to investigate whether the candidate genes are involved in the pathogenesis of euthyroid goiter. The markers for the genes TG, TPO, and NIS gave two-point and multipoint logarithm of odds score analysis scores that were negative or below 1 for all assumed recombination fractions. As no significant evidence of linkage was found, we conclude that these candidate genes can be excluded as a major cause of the euthyroid goiters in this family. In contrast, we have found evidence for linkage of familial euthyroid goiter to the recently identified locus for familial multinodular nontoxic goiter (MNG-1) on chromosome 14q. The haplotype cosegregates clearly with familial euthyroid goiter. Our results provide the first confirmation for MNG-1 as a locus for nontoxic goiter.

Regeneration of dorsal column fibers into and beyond the lesion site following adult spinal cord injury

Regeneration is abortive following adult mammalian CNS injury. We have investigated whether increasing the intrinsic growth state of primary sensory neurons by a conditioning peripheral nerve lesion increases regrowth of their central axons. After dorsal column lesions, all fibers stop at the injury site. Animals with a peripheral axotomy concomitant with the central lesion show axonal growth into the lesion but not into the spinal cord above the lesion. A preconditioning lesion 1 or 2 weeks prior to the dorsal column injury results in growth into the spinal cord above the lesion. In vitro, the growth capacity of DRG neurite is also increased following preconditioning lesions. The intrinsic growth state of injured neurons is, therefore, a key determinant for central regeneration.

Purification and properties of the F1F0 ATPase of Ilyobacter tartaricus, a sodium ion pump

The ATPase of Ilyobacter tartaricus was solubilized from the bacterial membranes and purified. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme revealed the usual subunit pattern of a bacterial F1F0 ATPase. The polypeptides with apparent molecular masses of 56, 52, 35, 16.5, and 6.5 kDa were identified as the alpha, beta, gamma, epsilon, and c subunits, respectively, by N-terminal protein sequencing and comparison with the sequences of the corresponding subunits from the Na(+)-translocating ATPase of Propionigenium modestum. Two overlapping sequences were obtained for the polypeptides moving with an apparent molecular mass of 22 kDa (tentatively assigned as b and delta subunits). No sequence could be determined for the putative a subunit (apparent molecular mass, 25 kDa). The c subunits formed a strong aggregate with the apparent molecular mass of 50 kDa which required treatment with trichloroacetic acid for dissociation. The ATPase was inhibited by dicyclohexyl carbodiimide, and Na+ ions protected the enzyme from this inhibition. The ATPase was specifically activated by Na+ or Li+ ions, markedly at high pH. After reconstitution into proteoliposomes, the enzyme catalyzed the ATP-dependent transport of Na+, Li+, or Hi+. Proton transport was specifically inhibited by Na+ or Li+ ions, indicating a competition between these alkali ions and protons for binding and translocation across the membrane. These experiments characterize the I. tartaricus ATPase as a new member of the family of FS-ATPases, which use Na+ as the physiological coupling ion for ATP synthesis.

Metastatic renal cell carcinoma: long-term survival after therapy with high-dose continuous-infusion interleukin-2

PURPOSE

This article undertakes to define the response rate, long-term survival, and toxicity in patients with metastatic renal cell carcinoma (MRCC) treated with high-dose continuous intravenous infusion (CIV) recombinant interleukin-2 (rIL-2) with or without lymphokine-activated killer (LAK) cells.

PATIENTS AND METHODS

One hundred twenty-three consecutive patients received CIV rIL-2 (18-22 MIU/m2/day on days 1-5, and 6-8 MIU/m2/day on days 10-19) on one of five sequential protocols at the University of Washington between 1988 and 1995. The first 76 patients received LAK cells. The median age was 55 years (range, 32-76 years), and 71% had undergone prior nephrectomy.

RESULTS

Nine patients achieved a complete response (7.3%) and 14 patients achieved a partial response (11.4%) for an overall response rate of 19% (95% confidence interval, 12%-26%). The median survival was 19 months, and the 5-year survival was 20%. Seven of nine complete responders (78%) remain in continuing complete response at 43+ to 109+ months. Intensive care unit and vasopressor support were required in 42% and 23% of patients, respectively, who received rIL-2 + LAK cells, and in 18% and 4% of those who received rIL-2 alone. There was one treatment-related death.

CONCLUSION

We report the largest single-institution experience and the longest survival for patients with MRCC treated with CIV rIL-2. The administration of rIL-2 by CIV is associated with less frequent intensive care unit and vasopressor support than with high-dose intravenous bolus regimens, and hence may enhance the therapeutic index in patients with MRCC.

The ssb-113 allele suppresses the dnaQ49 mutator and alters DNA supercoiling in Escherichia coli

Mutations in the dnaQ gene, which encodes the proofreading epsilon-subunit of the DNA polymerase III holoenzyme, lead to a mutator phenotype caused by enhanced error rates during DNA replication. In this paper, we studied the influence of ssb mutations on the dnaQ49 mutator, because of the involvement of SSB protein in DNA replication. We found that the ssb-113 mutation suppresses the mutator phenotype of dnaQ49. The suppression effect resulted from an enhanced expression of the dnaQ49 allele as determined by experiments with gene fusions. S1 nuclease analysis revealed that the increased dnaQ expression is based on transcriptional activation of the dnaQP2 promoter. This seems to be the consequence of an increased DNA supercoiling in the ssb-113 mutant, which also influenced further functions that are sensitive to alterations in DNA supercoiling. These results support the hypothesis that the expression of the epsilon-subunit of DNA polymerase III may additionally be modulated by DNA supercoiling, and suggest a possible role for DNA topology in mutagenesis.