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Biomedical subjects

R Frank

Publications and source records attributed to R Frank.

At least 217 records · Page 12Linked to original sources
PubMed1993

Partial purification and characterization of early and late endosomes from yeast. Identification of four novel proteins.

Previously (Singer, B., and Riezman, H. (1990) J. Cell Biol. 110, 1911-1922), we provided evidence for the existence of an endocytic intermediate(s) from the yeast Saccharomyces cerevisiae that is responsible for the transport of the pheromone alpha-factor from the plasma membrane to the vacuole. Here we show by kinetic analysis that the endocytic apparatus of yeast is composed of early and late endosomes, similar to what has been found in animal cells. We have developed a three-step isolation procedure to purify early and late endosomes, consisting of differential centrifugation, flotation on a Nycodenz density gradient, and sedimentation density gradient centrifugation on sucrose/D2O. Using internalized 35S-alpha-factor as a marker, the endosomal fractions were substantially enriched over other membranes, except for Golgi elements and a compartment containing binding protein. These contaminants could not be removed by other standard purification methods. We have analyzed the protein composition of our most pure early and late endosome fractions. By two-dimensional gel analysis we identified more than 20 proteins spots that are highly enriched in the early/late endosomal fractions. N-terminal protein sequencing resulted in the identification of four novel proteins.

Amino Acid Sequence↗
PubMed1993

Histoplasmosis of the penis.

Histoplasmosis is a common cause of systemic mycosis in endemic areas of the United States. Genitourinary and cutaneous involvement with this dimorphous fungus is rare. We report a case of disseminated histoplasmosis associated with nonpainful ulcerative lesions of the glans and shaft of the penis.

Aged↗
PubMed1993

Assembly of the 68- and 72-kD proteins of signal recognition particle with 7S RNA.

Signal recognition particle (SRP), the cytoplasmic ribonucleoprotein particle that mediates the targeting of proteins to the ER, consists of a 7S RNA and six different proteins. The 68- (SRP68) and 72- (SRP72) kD proteins of SRP are bound to the 7S RNA of SRP as a heterodimeric complex (SRP68/72). Here we describe the primary structure of SRP72 and the assembly of SRP68, SRP72 and 7S RNA into a ribonucleoprotein particle. The amino acid sequence deduced from the cDNA of SRP72 reveals a basic protein of 671 amino acids which shares no sequence similarity with any protein in the sequence data libraries. Assembly of SRP72 into a ribonucleoprotein particle required the presence of 7S RNA and SRP68. In contrast, SRP68 alone specifically bound to 7S RNA. SRP68 contacts the 7S RNA via its NH2-terminal half while COOH-terminal portions of SRP68 and SRP72 are in contact with each other in SRP. SRP68 thus serves as a link between 7S RNA and SRP72. As a large NH2-terminal domain of SRP72 is exposed on SRP it may be a site of contact to other molecules involved in the SRP cycle between the ribosome and the ER membrane.

Amino Acid Sequence↗
PubMed1993

6-Phospho-beta-galactosidases of gram-positive and 6-phospho-beta-glucosidase B of gram-negative bacteria: comparison of structure and function by kinetic and immunological methods and mutagenesis of the lacG gene of Staphylococcus aureus.

The 6-phospho-beta-galactosidase of Staphylococcus aureus, Lactococcus lactis and Lactobacillus casei and 6-phospho-beta-glucosidase B of Escherichia coli build a subfamily inside a greater enzyme family, named the glycosal hydrolase family 1, which, in addition, contains nine beta-glycosidases of different origins. Kinetic and immunological evidence is provided in this report which strengthens the relationship of the four 6-phospho-beta-glycosidases. It is shown that the 6-phospho-beta-galactosidases and 6-phospho-beta-glucosidase B are able to split aromatic beta-galactoside phosphates and beta-glucoside phosphates. The turnover numbers of hydrolysis of substrates with different epimerization at C-4 of the glycon vary up to 15-fold only. Two polyclonal antisera, one derived against the native 6-phospho-beta-galactosidase from S. aureus and the other derived against the 6-phospho-beta-glucosidase B, cross-reacted with both enzymes. Peptides of the proteins were separated by reverse phase HPLC. The cross-reacting peptides were sequenced and shown to be localized at almost the same position in the aligned primary structures of both enzymes. An insertion of nine amino acids near these antigenic domains is unique for the 6-phospho-beta-glycosidases and missing within the sequences of the beta-glycoside-specific members of the family. The lacG gene of a 6-phospho-beta-galactosidase negative S. aureus mutant was cloned into E. coli and sequenced. In the totally inactive mutant protein only the glycine at position 332 was changed to an arginine. This amino acid is part of the sequence insertion near the antigenic domain reacting with both antisera.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Immunohistochemical characterization of the plasminogen activator system in psoriatic epidermis.

The relative topographical distribution of urokinase-type plasminogen activator (uPA), tissue-type PA (tPA), PA-inhibitor-1 (PAI-1), PA-inhibitor-2 (PAI-2), plasmin(ogen), alpha 2-antiplasmin, and alpha 2-macroglobulin was studied in lesional epidermis of psoriasis vulgaris, and in normal epidermis, by immunohistochemistry. In psoriatic epidermis, tPA predominated, although uPA was found in some biopsies. PAs were not detected in normal epidermis. PAI-1 was not detected in normal epidermis and was only present in a proportion of biopsies of psoriatic lesions. PAI-2 was found in normal and psoriatic epidermis. Plasmin(ogen) was confined to the basal cell layer of normal epidermis, whereas in lesional psoriatic skin it was scattered throughout the epidermis. Alpha 2-antiplasmin and alpha 2-macroglobulin were not found in the epidermis of normal skin. In psoriatic epidermis alpha 2-antiplasmin was confined to the subcorneal layer, whereas staining for alpha 2-macroglobulin was found only in a proportion of biopsies, in the upper epidermis. Our immunohistological findings indicate that colocalization of tPA and its substrate plasminogen may allow efficient generation of plasmin, and that the focal absence of plasmin inhibitors may then favour the persistence of plasmin activity.

Adult↗
PubMed1993

Acute exposure to acid fog. Effects on mucociliary clearance.

Submicrometric sulfuric acid (H2SO4) aerosol can affect mucociliary clearance without eliciting irritative symptoms or changes in pulmonary function. The effect of larger fog droplets containing H2SO4 on mucociliary clearance is unknown. We quantified mucociliary clearance from the trachea (n = 4) and small airways (n = 7) of young healthy male adults after an acute exposure to H2SO4 fog (MMAD = 10.3 microns; pH = 2.0; liquid water content = 481 +/- 65 mg/m3; osmolarity = 30 mOsm). Acid fog (AF) or saline fog (SF) (10.9 microns; 492 +/- 116 mg/m3; 30 mOsm) was administered for 40 min of unencumbered breathing (no mouth-piece) at rest and for 20 min of exercise sufficient to produce oronasal breathing. Fog exposures were followed by a methacholine (MCh) challenge (a measure of airway reactivity) or inhalation of technetium-99M radioaerosol (MMAD = 3.4 microns) on 2 study days each. Changes in symptoms and forced ventilatory function were also assessed. Clearance was quantified from computer-assisted analyses of gamma camera images of the lower respiratory tract in terms of %removal/min of the radiolabel from the trachea 25 min after inhalation and from the outer zone of the right lung after 1.9 to 3 h. Symptoms, forced ventilatory function, and MCh response were unaffected by either fog. Tracheal clearance was more rapid in four of four subjects after AF (0.83 +/- 1.58% removal/min) compared with that after SF (-0.54 +/- 0.85% removal/min). Outer zone clearance was more rapid in six of seven subjects after AF (0.22 +/- 0.15% removal/min) compared with that after SF (0.01 +/- 0.09% removal/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Site-directed mutagenesis of the 2-haloalkanoic acid dehalogenase I gene from Pseudomonas sp. strain CBS3 and its effect on catalytic activity.

Two 2-haloalkanoic acid dehalogenases from Pseudomonas sp. strain CBS3 catalyse hydrolytic dehalogenation of chloroacetate and 2-chloropropionate. We used site-directed mutagenesis to introduce specific changes in the dehalogenase I encoding gene (dehCI). Substitution of Asp-10 by Ala-10 resulted in complete loss of dehalogenating activity although expression of the 2-haloacid dehalogenase I was not affected in the mutant as shown by western blot analysis, and although comparison of the mutated enzyme with the wild type enzyme indicated that extensive rearrangements in the three-dimensional structure of the enzyme had not occurred. From these data we suggest that Asp-10 of 2-haloacid dehalogenases I from Pseudomonas sp. strain CBS3 may be the nucleophilic residue in the active-site of this enzyme essential for halide release.

Amino Acid Sequence↗
PubMed1993

[Duration of QRS complexes in arrhythmogenic right ventricular dysplasia. A new non-invasive diagnostic marker].

Arrhythmogenic right ventricular dysplasia (ARVD) may result in sudden death of young and sometimes athletic individuals, while if properly treated it is associated with a good prognosis. It is probably more widespread than currently thought. Comparison of the electrocardiograms of 43 ARVD patients with those of 44 normal individuals provided a new criterion enabling identification of the disease. Measurement of a QRS interval longer than 110 ms in sinus rhythm in lead V1 in an individual with an apparently normal heart enabled identification of the disease with a sensitivity of 55 p. cent and specificity of 100 p. cent if used alone, and a sensitivity of 60 p. cent if used in combination with a prolongation of QRS in lead V3 to greater than 110 ms, but with a specificity of 82 p. cent. After elimination of appearances of right bundle branch block, sensitivity was 50 p. cent for V1. This parameter studied in a hospital population should be validated in minor forms before leading to compulsory ECGs for individuals in high-risk occupations (athletes, public vehicle drivers, etc.).

Adult↗
PubMed1993

[Treatment of ventricular tachycardia by endocardial fulguration. Apropos of 86 cases].

Between 1983 and 1991, 86 cases of ventricular tachycardia (VT) resistant to antiarrhythmic therapy were treated by endocardious catheter fulguration: there were 21 cases of right ventricular dysplasia (RVD), 35 chronic myocardial infarctions (MI), 11 dilated cardiomyopathies (DCM), 10 bundle branch VT, 5 idiopathic septal VT, 3 operated Fallot procedures, 1 Ebstein's anomaly. There were 69 men and 17 women aged 14 to 76 years (average 45 +/- 18 years). The ejection fraction was under 30% in 37 cases. Forty-five VTs were permanent or recurred several times daily; 6 were inducible despite drug therapy and 35 patients had monthly recurrences. A total of 141 different forms of VT were treated in 133 procedures. One session was sufficient in 49 cases; 2 sessions were required in 29 cases; 3 sessions in 6 cases and 4 sessions in 2 cases. A total of 480 DC shocks were delivered with energies of 160 to 300 joules. The CPK-MB levels were 37 +/- 30 i.u./l. The following complications were observed: 7 perioperative deaths, 2 cardiac tamponades requiring surgical drainage, 1 permanent AV block, 5 reversible left ventricular failures. Follow up concerned 79 patients: 5 were followed up for less than 3 months with death occurring from cardiac failure which had been present before the ablation procedure without recurrence of VT. Seventy-four patients were followed up from 3 to 111 months (56 +/- 33 months). Thirty-two patients were without any antiarrhythmic therapy and had no recurrence of VT. Two of these patients developed a different form of VT 2 and 6 years after the catheter ablation.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1993

[Holter and sudden death: value in a case of arrhythmogenic right ventricular dysplasia].

The authors report the first case of arrhythmogenic right ventricular dysplasia presenting with a sudden death due to primary ventricular fibrillation (ventricular fibrillation not preceded by ventricular tachycardia) recorded by the Holter method. The patient was a 56 year old man whose only complaint was near syncopal case is the fact that it is the first documented case of ventricular fibrillation revealing arrhythmogenic right ventricular dysplasia, the diagnosis of which was made at autopsy. In addition, the Holter recording showed the factors which triggered the arrhythmia: the "trigger" of 4 monomorphic ventricular extrasystoles during the minute preceding the ventricular fibrillation; the arrhythmogenic substrate giving rise to late ventricular potentials and, finally, the analysis of the R-R intervals suggesting a role of the sympathetic and parasympathetic nervous systems. Holter recordings could help identify subjects at high risk of severe ventricular arrhythmias.

Adipose Tissue↗
PubMed1993

[Sustained monomorphic ventricular tachycardia in non ischemic heart diseases].

Sustained ventricular tachycardia in the absence of coronary artery disease is mainly observed in diffuse left ventricular cardiomyopathy especially dilated but sometimes hypertrophic, and in right sided cardiomyopathies such as ventricular dysplasia, more difficult to diagnose. More rarely, other localised abnormalities, mitral valve prolapse, cardiac tumour and idiopathic aneurysm, may give rise to this arrhythmia. Irrespective of the case, sustained ventricular tachycardia carries a poor prognosis during the most advanced stages of a myocardial disease. The therapeutic strategy remains the same as that of other cases of sustained ventricular tachycardia, drug therapy generally orientated by the results of programmed ventricular stimulation with the exception of Class I antiarrhythmics when the ejection fraction is under 30%, and non-pharmacological methods when drug therapy fails.

Anti-Arrhythmia Agents↗
PubMed1993

[Arrhythmogenic right ventricular dysplasia. A new clinical entity].

Arrhythmogenic right ventricular dysplasia has been identified in 1977. It affects the right ventricle and its etiology is unknown. It has been recently included in the group of cardiomyopathies since it affects mainly the right ventricular muscle. It is found in young adults, frequently sportsmen who have a nearly normal cardiac physical examination. Ventricular arrhythmias could lead to palpitations, syncopes or even sudden death. This accident could be the first presenting sign of the disease. Two physiopathogenic mechanisms have been considered: heredo-familial origin or the result of a burned out myocarditis which could be the result of an abnormal immunological response. Its treatment mainly involves antiarrhythmic drugs. In the resistant cases ablative techniques, implantable defibrillator or surgery and even cardiac transplantation could be considered. Correctly treated, ARVD has a good prognosis. More extensive studies are necessary both on the clinical as well as the basic science standpoints.

Adolescent↗
PubMed1992

Generation of specific antibodies against the rap1A, rap1B and rap2 small GTP-binding proteins. Analysis of rap and ras proteins in membranes from mammalian cells.

Specific antibodies against rap1A and rap1B small GTP-binding proteins were generated by immunization of rabbits with peptides derived from the C-terminus of the processed proteins. Immunoblot analysis of membranes from several mammalian cell lines and human thrombocytes with affinity-purified antibodies against rap1A or rap1B demonstrated the presence of multiple immunoreactive proteins in the 22-23 kDa range, although at strongly varying levels. Whereas both proteins were present in substantial amounts in membranes from myelocytic HL-60, K-562 and HEL cells, they were hardly detectable in membranes from lymphoma U-937 and S49.1 cyc- cells. Membranes from human thrombocytes and 3T3-Swiss Albino fibroblasts showed strong rap1B immunoreactivity, whereas rap1A protein was present in much lower amounts. In the cytosol of HL-60 cells, only small amounts of rap1A and rap1B proteins were detected, unless the cells were treated with lovastatin, an inhibitor of hydroxymethylglutaryl-coenzyme A reductase, suggesting that both proteins are isoprenylated. By comparison with recombinant proteins, the ratio of rap1A/ras proteins in membranes from HL-60 cells was estimated to be about 4:1. An antiserum directed against the C-terminus of rap2 reacted strongly with recombinant rap2, but not with membranes from tested mammalian cells. In conclusion, rap1A and rap1B proteins are distributed differentially among membranes from various mammalian cell types and are isoprenylated in HL-60 cells.

Amino Acid Sequence↗
PubMed1992

Three-dimensional in vivo mapping of brain lesions in humans.

We describe a multistep technique for three-dimensional reconstruction and analysis of brain lesions in vivo, based on the manipulation of magnetic resonance raw data obtained with a special protocol. The technique permits the direct visual identification of neuroanatomical landmarks in each brain specimen and eliminates the need to rely on averaged templates of human brain sections, which can be a source of lesion localization error. The technique also allows for the bidirectional cross-reference between data points in two-dimensional slices and in volume reconstruction and for the projection of subcortical structures onto the three-dimensional cortical surface. The three-dimensional lesion mapping technique can be applied to research with the lesion method in both human and nonhuman primates, to the planning of neurosurgical lesion approach, and to the teaching of neuroanatomy.

Brain Diseases↗
PubMed1992

The chicken neural extracellular matrix molecule restrictin: similarity with EGF-, fibronectin type III-, and fibrinogen-like motifs.

Restrictin is a chick neural extracellular matrix protein implicated in neural cell attachment and found to be associated with the cell surface recognition protein F11. Here we show by cDNA cloning that restrictin is a large multidomain protein composed of 4 structural motifs. At the N-terminus restrictin contains a cysteine-rich segment of about 140 aa that might link restrictin monomers into oligomers. This region is followed by 4.5 epidermal growth factor-like repeats and then by 9 consecutive motifs that are similar to fibronectin type III motifs. At the C-terminus restriction is related to the beta and gamma chains of fibrinogen, including similarity to a calcium-binding segment. Restrictin shows substantial sequence similarity with tenascin (cytotactin) throughout the polypeptide, and like tenascin, it forms oligomeric structures, as revealed by electron microscopy of immunoaffinity-purified restriction. The cell attachment site of restrictin is mapped to the C-terminal region by antibody perturbation experiments.

Amino Acid Sequence↗