PubMed Health⌕ Search

Biomedical subjects

T Rose

Publications and source records attributed to T Rose.

At least 55 records · Page 3Linked to original sources
PubMed1995

Interaction of calcium with Bordetella pertussis adenylate cyclase toxin. Characterization of multiple calcium-binding sites and calcium-induced conformational changes.

The adenylate cyclase (CyaA) secreted by Bordetella pertussis is a toxin that is able to enter eukaryotic cells and cause a dramatic increase in cAMP level. In addition, the toxin also exhibits an intrinsic hemolytic activity that is independent from the ATP cycling catalytic activity of the toxin. Both the cytotoxic and hemolytic activities are calcium-dependent. In this work, we have analyzed the calcium interacting properties of CyaA. We have shown that CyaA exposed to CaCl2 could retain membrane binding capability and hemolytic activity when it was further assayed in the presence of an excess of EGTA. Determination of the calcium content of CyaA exposed first to calcium and subsequently to EGTA indicated that some (3-5) calcium ions remained bound to the protein, suggesting the existence of Ca2+ binding sites of high affinity. Binding of Ca2+ to these sites might be necessary for both the membrane binding capability and the hemolytic activity of the toxin. In addition, CyaA possesses a large number (about 45) of low affinity (KD = 0.5-0.8 mM) Ca2+ binding sites that are located in the C terminus of the toxin, between amino acids 1007 and 1706. This region mainly consists of about 45 repeated sequences of the type GGXGXDXLX (where X represents any amino acid) that are characteristic of the RTX (Repeat in ToXin) bacterial protein family. Our data suggest that each one can bind one calcium ion. Circular dichroism spectroscopy analysis showed that calcium binding to the low affinity sites induces a large conformational change of CyaA, as revealed by an important increase in the content of alpha-helical structures. This conformational change might be directly involved in the Ca(2+)-dependent translocation of the catalytic domain of CyaA through the plasma membrane of target cells.

Adenylate Cyclase Toxin↗
PubMed1995

Solution structure of a homopyrimidine: homopurine dodecamer encoded by the HIV-1 envelope gene: NMR and molecular simulation studies.

The solution structure of the nonpalindromic dodecanucleotide homopyrimidine:homopurine, d(5'-TTTCTCCTTTCT):d(5'-AGAAAGGAGAAA), was determined by two-dimensional nuclear magnetic resonance spectroscopy combined with molecular simulation. The dodecamer sequence studied was found within the HIV-1 envelope sequence and had all four Gs substituted by A in two hypermutants. A set of low-energy B-DNA conformations satisfying the quantitative NOE data were obtained. These highly related structure had neither peculiar helical parameters for the base pairs nor axis curvature. Analysis of the dihedral angles (epsilon-zeta) suggests that the A stretches flanking the GpA dinucleotides were more flexible.

Base Sequence↗
PubMed1995

Prenatal diagnosis and fetopathological findings in five fetuses with trisomy 9.

Five male fetuses with trisomy 9 are discussed. Three were detected prenatally and terminated, 1 aborted spontaneously, and the fifth delivered prematurely and died soon after. Multiple congenital abnormalities characteristic of trisomy 9 were detected in all 5 cases and are compared to those of previous reports.

Abnormalities, Multiple↗
PubMed1995

Restriction of self-antigen presentation to cytolytic T lymphocytes by mouse peptide pumps.

Transport of an immunogenic self-peptide from the second domain of the mouse major histocompatibility complex (MHC) H-2Kd class I molecule is blocked at the TAP1-TAP2 peptide pump level due to its amino acid sequence and is not presented to cytolytic T lymphocytes (CTL). We demonstrate that first, TAP1-TAP2 pumps can restrict antigen presentation by selecting against internal peptide motifs which are not involved in peptide binding to MHC class I molecules. Second, some molecules targeted to the endoplasmic reticulum are processed for MHC class I presentation in the cytosol. Third, some abundantly expressed immunogenic self-peptides are cytosolically sequestered. The advantage for the host, in terms of the peripheral T cell repertoire is that the spared CTL can be used to recognize foreign antigens. It is, however, anticipated that this advantage will be exploited by pathogens to evade immune surveillance by similar strategies.

ATP-Binding Cassette Transporters↗
PubMed1995

Treatment of psoriasis at a Dead Sea dermatology clinic.

BACKGROUND: The Dead Sea, with its unique optical, chemical, and atmospheric properties, provides an effective alternative treatment for psoriasis. METHODS: The records of 1448 consecutive psoriasis patients treated at a Dead Sea psoriasis clinic were retrospectively evaluated concerning their treatment response and demographic characteristics. RESULTS: Clearing of 80-100% was observed in 88% of the patients treated, including almost 58%, who had complete clearing. The demographic data studied that included gender, previous treatment at the Dead Sea, prior history of hospitalization for psoriasis, prior PUVA treatment, or a history of arthritis did not reveal any significant relationships, although overseas patients responded considerably better than Israelis. CONCLUSIONS: The overall response in a large cohort of psoriasis patients treated at the Dead Sea was excellent. Further prospective studies and basic investigations are essential to understand the mechanism(s) involved and the relationships between other demographic data and the treatment response.

Balneology↗
PubMed1995

Conformational behaviour of a synthetic peptide of the C-terminus of villin that interacts with actin: an NMR, CD and stimulated annealing study.

The solution structure of a synthetic 22-amino acid peptide (P1) corresponding to the extreme C-terminal end and one of the F-actin binding sites of villin has been determined by 1H NMR and CD spectroscopy. The structure of this peptide was compared to that of a peptide in which lysine to glutamic acid substitutions were introduced at positions 17 and 19 (P11), abolishing F-actin binding. Both peptides are largely unstructured in aqueous solution. Changes observed in the NMR and CD spectra of both peptides are consistent with alpha-helix formation in trifluoroethanol/water mixtures. A set of 189 interproton distances derived from nuclear Overhauser enhancement (NOE) measurements, 17 phi-angle constraints obtained from 3JNH alpha coupling constants, as well as about 10 N ... O distance restraints deduced from amide proton exchange kinetics with deuterium, were used for the structure determination. The three-dimensional structure of P1 and P11 is characterized by two helical regions, one extending from residues 2 to 5 and a second covering residues 7 to 17. The central fragment, ranging from Leu-7 to Leu-15, is more stable. The C-terminal residues are less structured, particularly within peptide P11. The significance of these structural results is discussed in relation to the biological activity of villin.

Actins↗
PubMed1994

Quantification of attention-related behaviors in individuals with traumatic brain injury. A pilot study.

Clinical disorders of attention are common after traumatic brain injury but objective measures of their nature and severity are lacking. We developed a standardized independent work task to be performed by patients in a controlled, distracting environment. Videotaped records of patient behavior were made and coded in 15-s intervals for on-task behavior, presence of distractors and presence of extraneous motor behavior. Interrater reliability was good to excellent across eleven testing sessions involving four patients. This evaluation system revealed clinically important differences in on-task behavior among the four patients, as well as different levels of distraction in response to external stimuli. It also showed effects of different tasks and repeated sessions. These data indicate that this evaluation system and accompanying coding process are reliable and provide preliminary evidence that they produce clinically valid results.

Adult↗
PubMed1993

Listeria-associated pericarditis in an AIDS patient.

Listeria monocytogenes is a pathogenic, facultative intracellular gram-positive rod, generally seen in cell-mediated immunocompromised states. In acquired immunodeficiency syndrome (AIDS), it most commonly presents as bacteremia or meningitis. An association with pericarditis has not been described previously in this group of patients. This article describes a case of pericarditis secondary to listeriosis involving a focal pancarditis and necrosis of the A-V node with subsequent refractory ventricular tachyarrhythmias in an immunodeficient patient presenting with altered mental status. Infectious etiologies should be considered for "benign" appearing pericardial effusions in AIDS patients and the diagnosis of listeriosis excluded in the presence of "diphtheroid-like" organisms.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Structural and functional consequences of amino acid substitutions in the second conserved loop of Escherichia coli adenylate kinase.

All known nucleoside monophosphate kinases contain an invariant sequence Asp-Gly-Phe(Tyr)-Pro-Arg. In order to understand better the structural and functional role of individual amino acid residues belonging to the above sequence, three mutants of Escherichia coli adenylate kinase (D84H, G85V, and F86L) were produced by site-directed mutagenesis. Circular dichroism spectra revealed that the secondary structure dichroism spectra revealed that the secondary structure of all three mutant proteins is very similar to that of the wild-type enzyme. However, each of the substitutions resulted in a decreased thermodynamic stability of the protein, as indicated by differential scanning calorimetry measurements and equilibrium unfolding experiments in guanidine HCl. The destabilizing effect was most pronounced for the G85V mutant, in which case the denaturation temperature was decreased by as much as 11 degrees C. The catalytic activity of the three mutants represented less than 1% of that of the wild-type enzyme. Furthermore, for the D84H-modified form of adenylate kinase, the impaired binding of nucleotide substrates was accompanied by a markedly decreased affinity for magnesium ion. These observations support the notion that Asp84 is directly involved in binding of nucleotide substrates and that this binding is mediated by interaction of the aspartic acid residue with divalent cation. The two remaining residues probed in this study, Gly85 and Phe86, belong to a beta-turn which appears to play a major role in stabilizing the three-dimensional structure of adenylate kinase.

Adenylate Kinase↗
PubMed1991

Structural and catalytic properties of a deletion derivative (delta 133-157) of Escherichia coli adenylate kinase.

Escherichia coli adenylate kinase (AKe) as well as the enzyme from yeast and mitochondria differs from the muscle cytosolic variant (AK1) by an insertion of 25 amino acid residues that are missing in AK1. The extra sequence, highly homologous in "large" size variants, is situated between residues 133 and 157 in AKe. Removal of 25 codons in the corresponding adk gene resulted in expression of a modified form of adenylate kinase (delta 133-157 AKe) which still conserved 7% of the maximal activity of the wild-type protein. The apparent Km for nucleotide substrates was increased by a factor of 4.6 (ADP), 23 (ATP) or 43 (AMP) in delta 133-157 AKe when compared with the wild-type enzyme. The secondary structure of delta 133-157 AKe, as well as its thermal stability were very similar to the parent protein. However, the deleted protein was much more sensitive than the wild-type enzyme to inactivation by trypsin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of trypsin digested delta 133-157 AKe revealed accumulation of several well defined fragments which were not observed in the case of wild-type enzyme. We conclude that the additional sequence, although necessary for expression of full activity in AKe, is not critical for catalysis. It is perhaps responsible for interaction of enzyme with other cellular components although a different mechanism of water shielding for large and small size variants of AK can be also envisaged.

Adenylate Kinase↗
PubMed1991

Structural and ligand-binding properties of a truncated form of Bacillus anthracis adenylate cyclase and of a catalytically inactive variant in which glutamine substitutes for lysine-346.

A truncated, 541-residue-long, Bacillus anthracis adenylate cyclase was expressed in Escherichia coli. The purified protein (CYA 62) exhibited catalytic and CaM-binding properties identical with those of the wild-type enzyme secreted by B. anthracis. The analysis of the secondary structure of the CYA 62 protein by Fourier transform infrared spectroscopy and circular dichroism revealed the dominance of beta-type structure. The protein shows a relatively low thermal stability with the midpoint denaturation temperature at 45 degrees C. A catalytically inactive variant of CYA 62 in which Gln substituted for Lys-346 (CYA 62 K346Q) was comparatively analyzed for its secondary structure and thermal stability, as well as ligand-binding properties with fluorescent derivatives of ATP and calmodulin. The K346Q variant of CYA 62 has a similar secondary structure and comparable calmodulin binding properties to those of the parent protein and exhibits only slightly reduced thermal stability (the apparent midpoint denaturation temperature is at 43 degrees C). Despite these similarities, the binding of 3'-anthraniloyl-2'-deoxy-ATP (a fluorescent ATP analogue) to the modified protein is severely impaired, from which we conclude that the prime function of Lys-346 in the wild-type enzyme from B. anthracis is to ensure tight binding of the nucleotide substrate to the active site.

Adenylyl Cyclases↗
PubMed1991

Prediction of lethal pulmonary hypoplasia and chorioamnionitis by assessment of fetal breathing.

Twenty-three pregnancies with fetuses at risk for pulmonary hypoplasia were studied weekly until delivery. The amount of time spent in fetal breathing activity was recorded under controlled conditions during 1 h using real-time ultrasound. An amniotic fluid index was determined. The clinicians and the pathologist were unaware of the ultrasound findings. Eight of 23 fetuses did not breathe at the last ultrasound examination. Three babies died of pulmonary hypoplasia and two of these showed fetal breathing before birth. The three deaths were associated with rupture of the membranes at less than or equal to 20 weeks gestation and of greater than or equal to 44 days duration. One infant developed bronchopulmonary dysplasia. The amniotic fluid index in these four pregnancies was low and the newborn infants had limb contractures. Chorioamnionitis/funisitis was noted in 13 placentas. Eight fetuses were assessed for fetal breathing within 2 days of birth. The lack of fetal breathing had sensitivity, specificity, positive and negative predictive values of 0.75 for chorioamnionitis/funisitis. In this pilot study the absence of fetal breathing was of no value in predicting lethal pulmonary hypoplasia, but was related to chorioamnionitis/funisitis. We recommend further studies of fetal breathing in relation to fetal/neonatal infections.

Chorioamnionitis↗
PubMed1991

Vibrio vulnificus. Hazard on the half shell.

Vibrio vulnificus is an extremely invasive gram-negative bacillus that causes bacteremia and shock. It should be suspected in any patient who is immunocompromised or has liver disease or hemochromatosis. Reduced gastric acidity may also increase the risk of infection if a patient presents with a history of ingesting raw shellfish (especially oysters) or trauma in brackish waters and skin lesions. Patients most commonly present with one of three clinical syndromes: primary septicemia, wound infection, or gastroenteritis. Treatment includes aggressive wound debridement, antibiotic therapy, and supportive care. Rapidly diagnosing and promptly initiating therapy are critical because V vulnificus infection is rapidly progressive and mortality approaches 100% if septic shock occurs.

Animals↗
PubMed1990

Intrinsic fluorescence of a truncated Bordetella pertussis adenylate cyclase expressed in Escherichia coli.

A truncated, 432 residue long, Bordetella pertussis adenylate cyclase expressed in Escherichia coli was analyzed for intrinsic fluorescence properties. The two tryptophans (Trp69 and Trp242) of adenylate cyclase, each situated in close proximity to residues important for catalysis or binding of calmodulin (CaM), produced overlapping fluorescence emission bands upon excitation at 295 nm. CaM, alone or in association with low concentrations of urea, induced important modifications in the spectra of adenylate cyclase such as shifts of the maxima and change in the shape of the bands. From these changes and from the fluorescence spectrum of a modified form of adenylate cyclase, in which a valine residue was substituted for Trp242, it was deduced that, upon binding of CaM to the wild-type adenylate cyclase, only the environment of Trp242 was affected. The fluorescence maximum of this residue, which is more exposed to the solvent than Trp69 in the absence of CaM, is shifted by 13 nm to shorter wavelength upon interaction of protein with its activator. Trypsin cleaved adenylate cyclase into two fragments, one carrying the catalytic domain, and the second carrying the CaM-binding domain (Ladant et al., 1989). The isolated peptides conserved most of the environment around their single tryptophan residues, as in the intact adenylate cyclase, which suggests that the two domains of truncated B. pertussis adenylate cyclase also conserved most of their three-dimensional structure in the isolated forms.

Adenylyl Cyclases↗
PubMed1989

Structural and catalytic role of arginine 88 in Escherichia coli adenylate kinase as evidenced by chemical modification and site-directed mutagenesis.

Phenylglyoxal inactivates Escherichia coli adenylate kinase by modifying a single arginine residue (Arg-88). ATP, ADP, P1,P5-di(adenosine 5')-pentaphosphate, and to a lesser extent AMP protect the enzyme against inactivation by phenylglyoxal. Site-directed mutagenesis of Arg-88 to glycine yields a modified form of adenylate kinase (RG88 mutant) closely related structurally to the wild-type protein as indicated by Fourier transform infrared spectroscopy, differential scanning calorimetry, and limited proteolysis. However, this modified protein has only 1% of the maximum catalytic activity of the wild-type enzyme and 5- and 85-fold higher apparent Km values for ATP and AMP, respectively, than the parent adenylate kinase. Arg-88, which is a highly conserved residue in all known molecular forms of adenylate kinases (corresponding to Arg-97 in muscle cytosolic enzyme), should be located inside a big cleft of the molecule, close to the phosphate-binding loop. It possibly stabilizes the transferable gamma-phosphate group from ATP to AMP in the transition state.

Adenosine Diphosphate↗
PubMed1989

[The left ventricular functional parameter in M-mode echocardiography in various administration rates of a loading dose of theophylline in premature infants].

The aim of study was to show a positive effect of theophylline on the cardiac pump function immediately after i.v. bolus injection of the loading dose. Therefore we recorded m-mode echocardiograms before and immediately after bolus injection (over 2-3 min) of 6 mg/kg theophylline. On studying 12 preterm infants we observed a reduction of the left ventricular shortening fraction and circumferential shortening velocity. In the second part of the study we administered the same dose of theophylline over a period of 20 min. No significant differences in m-mode echocardiographic parameters before and after infusion were seen. We attribute these results to incalculable effects of theophylline preload, wall distension, and afterload. Nonetheless slow application of theophylline loading dose is recommended in preterm infants.

Cardiac Output↗
PubMed1988

Conservative replacement of methionine by norleucine in Escherichia coli adenylate kinase.

Escherichia coli grown in limited methionine and excess norleucine media accumulate cyanogen bromide-resistant species of proteins after the methionine supply is exhausted. Bacteria, transformed by recombinant plasmid pIPD37 carrying the adk gene and grown under limiting methionine and excess norleucine, synthesize 16-20% of adenylate kinase molecules having all 6 methionine residues replaced by norleucine. Species showing only partial replacement of methionine residues by norleucine are identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after cyanogen bromide treatment of pure enzyme. Norleucine-substituted adenylate kinase shows structural and catalytic properties similar to the wild-type protein as indicated by circular dichroism spectroscopy and kinetic experiments but exhibits a much higher resistance to hydrogen peroxide inactivation under denaturing conditions.

Adenosine Monophosphate↗