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Biomedical subjects

R Frank

Publications and source records attributed to R Frank.

At least 271 records · Page 15Linked to original sources
PubMed1991

Antibody response to the negative regulatory factor (nef) in experimentally infected macaques: correlation with viremia, disease progression, and seroconversion to structural viral proteins.

The antibody response to structural and regulatory viral proteins was studied in 14 rhesus (Macaca mulatta) and 6 cynomolgus (Macaca fascicularis) macaques experimentally infected with HIV-2 or SIVMAC. To investigate the humoral antibody response to the negative regulatory factor (nef), the recombinant protein was expressed to high levels with recombinant vaccinia virus (VV). nef-specific antibodies were detected in 14 of 20 infected macaques (70%). In sera of all infected monkeys antibodies directed to the structural proteins gp120, p56, and p24 appeared 2 to 6 weeks postinfection. In contrast, the extent and the appearance of nef-specific antibodies during the course of infection varied considerably between individual animals. However, only in sera of four animals (20%) were nef-specific antibodies detectable as early as those against the core proteins p24 and p56. In SIVMAC-infected rhesus macaques at different clinical stages, the antibody response towards nef neither correlated with the development of viral latency nor to disease progression or viremia. Our data indicate that in macaques experimentally infected with SIV or HIV-2 antibody formation against nef is not a useful diagnostic marker either for early detection of viral infection or of disease progression.

AIDS-Related Complex↗
PubMed1991

The solution structure of a leucine-zipper motif peptide.

We report the complete structure determination of a 34 residue synthetic peptide with the amino acid sequence of the dimerization domain (leucine zipper) of GCN4. A high resolution structure in solution was obtained by 1H-NMR studies and distance geometry calculations followed by restrained energy minimization. A set of 20 final structures was obtained with an average root mean square deviation of 1.3 A for the backbone atoms (excluding the first and the last two residues). The structure contains an uninterrupted helix. A comparison with a structure previously determined for a larger peptide containing both the DNA-binding region (basic region) and the leucine-zipper motif shows the structural independence of the leucine-zipper domain from the contiguous DNA binding region.

Amino Acid Sequence↗
PubMed1991

Complete nucleotide sequences and comparison of the structural genes of two 2-haloalkanoic acid dehalogenases from Pseudomonas sp. strain CBS3.

The nucleotide sequences of two DNA segments from Pseudomonas sp. strain CBS3 that code for two different haloalkanoic acid halidohydrolases were determined. Two open reading frames with coding capacities of 227 amino acids (corresponding to a molecular mass of 25,401 Da) and 229 amino acids (corresponding to a molecular mass of 25,683 Da) were identified as structural genes of 2-haloalkanoic acid dehalogenases I (dehCI) and II (dehCII) by comparison with the N-terminal amino acid sequences of these enzymes. Comparison of the two sequences revealed 45% homology on the DNA level and 37.5% homology on the amino acid level. No homology with other known protein or nucleotide sequences was found.

Amino Acid Sequence↗
PubMed1991

Human papillomavirus type 18 E6 and E7 antibodies in human sera: increased anti-E7 prevalence in cervical cancer patients.

Antibody-reactive regions on the human papillomavirus type 18 (HPV-18) E6 and E7 proteins were identified with rabbit polyclonal anti-fusion protein sera by screening of an fd phage expression library containing subgenomic HPV-18 DNA fragments and by testing of overlapping decapeptides representing the E6 and E7 open reading frames. Peptides comprising the delineated regions (designated E6/1 to E6/4 and E7/1) were synthesized and used in an enzyme-linked immunosorbent assay (ELISA) to detect anti-HPV-18 antibodies in human sera. A total of 232 human serum samples (identical numbers of cervical cancer patients and age-matched controls) collected in Tanzania were tested. Similar prevalences (between 0.8 and 4.3%) of antibodies recognizing the different E6 peptides were found in the sera from tumor patients and controls. With a synthetic 28-mer peptide (designated pepE701) comprising the E7/1 region, a significant difference was found: 10 of 116 tumor serum samples but 0 of 116 control serum samples showed a specific reaction (P less than 0.001). This observation confirms earlier results with HPV-16 E7 fusion proteins (I. Jochmus-Kudielka, A. Schneider, R. Braun, R. Kimmig, U. Koldovsky, K. E. Schneweis, K. Seedorf, and L. Gissmann, J. Natl. Cancer Inst. 81:1698-1704, 1989). A lower prevalence of anti-HPV-18 E7 antibodies was observed when 188 human serum samples collected in Germany from tumor patients and controls were tested (3 of 94 positive in the cancer group; 0 of 94 positive in the control group). The type specificity of anti-HPV-18 E7 antibodies was demonstrated when the HPV type found by Southern hybridization in the cervical cancer biopsies was compared with seroreactivity: 4 of 8 serum samples obtained from HPV-18 DNA-positive but 0 of 16 serum samples from HPV-18 DNA-negative tumor patients reacted in the HPV-18 E7 ELISA. In addition, HPV-18-positive sera failed to react in a peptide ELISA with the homologous HPV-16 E7 region (M. Müller, H. Gausepohl, G. de Martinoff, R. Frank, R. Brasseur, and L. Gissmann, J. Gen. Virol. 71:2709-2717, 1990) and vice versa.

Amino Acid Sequence↗
PubMed1991

Utilization of health services in a cohort of intravenous drug users with known HIV-1 serostatus.

BACKGROUND: Intravenous drug users (IVDUs) with human immunodeficiency virus (HIV) infection and AIDS often have no health insurance or rely on public programs to finance their health care. We examined the independent contributions of HIV serostatus, clinical symptoms, CD4 cell counts, and health insurance to utilization of health services among 1881 intravenous drug users in Baltimore, Maryland. METHODS: Participants in an ongoing natural history study of HIV were informed of HIV serostatus and seropositives were informed of CD4 cell counts; 6 months later, participants were administered a questionnaire concerning self-reported use of health services, insurance coverage, and HIV-related symptoms. RESULTS: Of 1881 participants, 67% had health insurance (including Medicaid), 48% had at least one outpatient visit, and 12% had at least one inpatient visit within the prior 6 months. The proportion of the study population that was HIV-1 seropositive was 32%. In multivariate analysis, the single most important predictor of health care utilization was the presence of two or more HIV-related clinical symptoms. HIV positive serostatus alone or known low CD4 counts were not significantly associated with use of health care services. CONCLUSIONS: These data suggest that HIV seropositive IVDUs are not receiving recommended preventive care. Additional efforts will be needed to ensure that HIV-seropositive drug users participate in currently recommended protocols for early treatment of asymptomatic HIV-1 infection.

Adult↗
PubMed1991

[The role of Holter monitoring and electrophysiological studies in the evaluation of ventricular anti-arrhythmia agents].

The roles of Holter monitoring and electrophysiological studies (EPS) in the evaluation of antiarrhythmic drugs for ventricular arrhythmias are to record their effects on ventricular extrasystoles (VES) and ventricular tachycardia (VT), and to search for undesirable rhythmological effects. The usual protocol is to perform baseline studies and then repeat them after a certain period of treatment using a number of modalities, comparison with placebo, control group, in acute or oral administration. Holter monitoring is an economical non-invasive method which carries no risk. Spontaneous arrhythmias of sufficient frequency to be recorded during the monitoring period can be studied. When applied to VES, it provides quantitative rather than qualitative information despite classifications such as Lown's. The results should be analysed taking spontaneous variations of the arrhythmia into consideration. Holter monitoring may also reveal proarrhythmic drug effects (bradycardia, torsades de pointe). However, there are no absolute criteria of efficacy except total suppression of VES, unexplainable by spontaneous variability. Holter antiarrhythmic studies require stable VES which creates a bias in the evaluation of results due to the special selection of patients. Electrophysiological studies are costly, invasive and uncomfortable but they are the only way of assessing paroxysmal VT apart from clinical follow-up. This method is only applicable to inducible VT, which is the commonest form. The investigating protocols are specific and reproducible: a tachycardia which is non-inducible does not recur in 90% of cases, which enables prediction of the antiarrhythmic effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗
PubMed1991

[Doppler echocardiography of the effect of atrioventricular delay on transmitral flow in dual chamber pacing. Role of associated cardiopathy].

Doppler echocardiography was used to analyse transmitral blood flow in 23 patients undergoing DDD pacing under basal conditions at a pacing rate of 70/min. Changes in the atrioventricular delay led to changes in Doppler parameters corresponding to the different phases of ventricular filing. When the atrioventricular interval was increased, the maximum velocity, the velocity time integral and the duration of the E wave decreased and the maximum velocity, the velocity time integral and duration of the A wave increased. The atrial contribution to left ventricular filing increased by 15 to 46% (p less than 0.001). The changes of the Doppler parameters with respect to the duration of the atrioventricular interval varied according to the patient group studied. Patients without ventricular dilatation with or without hypertrophy had greater maximum velocities and velocity time integrals of the A wave than patients with left ventricular dilatation. However, for the same changes in atrioventricular delay, the A wave and atrial contribution to left ventricular filing were more variable in patients without left ventricular dilatation than those with left ventricular dilatation confirming the greater sensitivity of patients without left ventricular dilatation to the setting of the atrioventricular interval. These results confirm the great variability of transmitral flow with changes in atrioventricular delay. They illustrate the need for appropriate programming of the atrioventricular delay especially in patients in whom the mitral flow is most sensitive to this adjustment.

Aged↗
PubMed1991

The MYCN protein of human neuroblastoma cells is phosphorylated by casein kinase II in the central region and at serine 367.

The MYCN gene has been implicated in certain neuronal tumours, such as neuroblastomas and retinoblastomas. These tumours express high levels of mRNA and protein of MYCN as a result of amplification. MYCN encodes a short-lived nuclear phosphoprotein whose function has not yet been elucidated. This study was undertaken to determine the pattern of MYCN protein (pMYCN) phosphorylation in human neuroblastoma cells. We report that pMYCN is phosphorylated in vitro by purified casein kinase II (CK-II). Two-dimensional phosphopeptide maps showed that most of the phosphopeptides of pMYCN phosphorylated in vitro by CK-II correspond to those phosphorylated in vivo. Fine mapping of the phosphorylation sites was performed using two synthetic MYCN peptides corresponding to pMYCN CK-II consensus sequences. Both peptides were found to be phosphorylated by CK-II and competitively inhibited CK-II phosphorylation of pMYCN in vitro. Thus, we have localized two major CK-II phosphorylation sites in pMYCN, one to the highly acidic central region and the second to serine 367 proximal to the C-terminus. Our data demonstrate that pMYCN is a physiological substrate for CK-II and, since CK-II activity is stimulated in response to mitogens, CK-II phosphorylation of pMYCN may, therefore, represent one signal transduction pathway used by neuroblastoma cells.

Amino Acid Sequence↗
PubMed1991

[Results of surgical treatment of mechanical ileus of the small intestine].

Between 1982 and 1988 275 patients with obstruction of the small intestine were operated. The etiology of obstruction: adhesions 48%, malignancies 26%, strangulated hernias 8%. The duration of obstruction symptoms was 3.7 days prior to hospital admission and 1.9 days from admission to operation. 78% of patients had a history of previous laparotomies, in 73% there were serious accompanying diseases. Strangulation obstruction was found in 18% of patients. Operative procedures included small bowel resection in 30%, creation of stomata in 14%, and deviation anastomoses in 12%. Postoperative complications were mainly pulmonary. Median time of hospitalization was 24 days, hospital mortality amounted to 7.6%. A low mortality was encountered especially in strangulation obstruction and after resections. Reduction of surgery induced morbidity is primarily made responsible for the good results.

Aged↗
PubMed1991

[Surgical treatment results in colonic obstruction].

Between 1982 and 1988 94 patients with obstruction of the colon were operated (52 male, 42 female, median age 66 years). Carcinoma accounted for the majority of cases: in 51% of patients enteral, in 9% local tumor growth extraenteral, in 17% peritoneal carcinosis. Therapeutic procedures were chosen according to the necessities in benign courses and in extraenteral tumor growth. In obstructing colorectal carcinoma (48 patients) a policy of primary tumor resection was pursued. 48 patients (40%) developed postoperative complications, 3 patients (3.1%) had to be reoperated. The overall mortality rate in patients with acute obstructions of all courses was 9.6%, in patients with obstruction secondary to carcinoma 14.6%. 74% of patients with colorectal tumors had TNM tumor stage III and IV. The 5-years-survival rate amounted to 21% overall, but after primary tumor resection it was 47%.

Aged↗
PubMed1990

The 68 kDa protein of signal recognition particle contains a glycine-rich region also found in certain RNA-binding proteins.

Signal recognition particle (SRP) interacts with the signal sequence in nascent secretory and membrane proteins and directs them to the membrane of the endoplasmic reticulum. Membrane targeting is mediated by the 68 and the 72 kDa proteins of SRP. We have cloned and sequenced cDNA encoding the 68 kDa protein of canine signal recognition particle (SRP68). SRP68 is a basic protein comprised of 622 amino acid residues. Close to the amino terminus there is a glycine-rich region which SRP68 has in common with some RNA-binding proteins. SRP68 shares no detectable similarity to any of the proteins in data libraries.

Amino Acid Sequence↗
PubMed1990

Phosphorylation of the cytoplasmic domain of the bovine cation-independent mannose 6-phosphate receptor. Serines 2421 and 2492 are the targets of a casein kinase II associated to the Golgi-derived HAI adaptor complex.

A kinase activity of purified bovine brain clathrin-coated vesicles phosphorylates the bovine cation-independent mannose 6-phosphate receptor (CI-MPR) with high efficiency (Km approximately 50-100 nM). The kinase copurifies in gel filtration, adsorption on hydroxylapatite, and ion exchange chromatography with the HAI assembly proteins which are part of the coat of Golgi-derived clathrin-coated vesicles. The kinase is associated to the 47-kDa subunit of the complex and exhibits properties similar to a casein kinase II: it uses either ATP or GTP as substrate and its activity is stimulated by poly-L-lysine and inhibited by heparin. Using different domains of the CI-MPR as potential substrates, we show that the phosphorylation is restricted to its cytoplasmic domain. Inhibition studies using synthetic peptides and two-dimensional mapping of the tryptic phosphopeptides indicate that this posttranslational modification occurs on serines 2421 and 2492 of the full-length bovine CI-MPR precursor, residues which are located in typical casein-kinase II recognition sequences. Labeling of Madin-Darby bovine kidney cells followed by immunoprecipitation of the CI-MPR and analysis of the corresponding tryptic phosphopeptides shows that the same serines are phosphorylated in vivo.

Amino Acid Sequence↗
PubMed1990

RNA primary sequence or secondary structure in the translational initiation region controls expression of two variant interferon-beta genes in Escherichia coli.

Efficient expression in Escherichia coli (E. coli) of the human interferon-beta gene (IFN-beta) gene and of a chemically synthesized IFN-beta gene variant (506 base pairs; synIFN-beta) adapted to the E. coli codon usage, both fused to the E. coli atpE ribosome-binding site, is controlled either by primary sequence or by mRNA secondary-structure in the translational initiation region. High level expression of the natural human atpE/IFN-beta gene fusion is governed by the nucleotide composition preceding the initiator codon AUG. A single U----C exchange in the -2 or -1 position preceding the initiator codon AUG reduces the translational efficiency from 18% of total cellular protein to only 8% or 4%, respectively, while both U----C substitutions reduce IFN-beta expression below 1%. These sequence alterations interfere with efficient ribosome binding as revealed by toeprinting. They provide further evidence for the influence of the anticodon-flanking regions of tRNA(fMet) upon the initiation rate of translation. In contrast, translation of the synthetic variant atpE/synIFN-beta gene fusion is controlled by a moderately stable stem-loop structure (delta G = -4 kcal/mol; 37 degrees C) located within the coding region and overlapping the 30 S ribosomal subunit attachment site. That the stability of the hairpin interferes with the initiation of translation is inferred from site-directed mutagenesis and toeprint analyses. mRNA half-life in these variants is positively correlated with the rate of translation and involves two major endonucleolytic cleavage site 5'-upstream of the Shine-Dalgarno region.

Base Sequence↗