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Biomedical subjects

J Pfau

Publications and source records attributed to J Pfau.

At least 19 recordsLinked to original sources
PubMed1994

A site-specific endonuclease derived from a mutant Trp repressor with altered DNA-binding specificity.

Site-directed mutagenesis was used to construct mutant Trp repressors with each of the 38 possible single amino acid changes of the first 2 amino acid residues (Ile79 and Ala80) in the second "recognition" alpha-helix of the helix-turn-helix DNA-binding motif. Eight of these mutant repressors with Ile79 and Ala80 changes are more active than the wild-type protein when tryptophan is limiting, and are super-aporepressors. Eleven mutant repressors have extended DNA-binding specificies in vivo, and bind operators which the wild-type repressor cannot. One mutant repressor, Lys79, has a classical altered specificity phenotype in vivo, and binds the wild-type trp operator less well than wild-type repressor, yet binds a mutant operator better than wild-type repressor. A site-specific nuclease was derived from Lys79 repressor by constructing a double-mutant protein with Lys79 and a sole cysteine residue, Cys49, and alkylating this cysteine with a 1,10-phenanthroline-copper adduct. This nuclease has an altered specificity of DNA binding in vitro. When activated by the addition of thiol and hydrogen peroxide, the Lys79 nuclease cleaves operator DNA within its new recognition sequence with high efficiency.

Bacterial Proteins↗
PubMed1994

Mutants of Escherichia coli Trp repressor with changes of conserved, helix-turn-helix residue threonine 81 have altered DNA-binding specificities.

Threonine is found at the third position of the second alpha-helix in the helix-turn-helix motifs of most bacterial DNA-binding proteins. To investigate the role of this conserved residue in Escherichia coli Trp repressor function, plasmids encoding mutant Trp repressors with each of the 19 amino acid changes of Thr-81 were made by site-directed mutagenesis. All 19 changes decrease the activity of Trp holorepressor, indicating that the Thr-81 side-chain is critical for TrpR function. Three mutant repressors, Ser-81, Lys-81 and Arg-81, retain partial DNA-binding activity and inhibit transcription from the wild-type trp promoter/operator complex; challenge-phage assays show that Ser-81 and Lys-81 holorepressors have altered DNA-binding specificities. The side-chain of Thr-81 may make direct contacts with base pairs 4 and 3 of the trp operator, consistent with the nuclear magnetic resonance solution structures of the holorepressor-operator complex.

Amino Acid Sequence↗
PubMed1994

[Surgical aspects of liver resection based on 5 years' data].

From 1988 to 1993 thirty liver resections were performed in thirty patients. Eight were operated for suffering from hepatocellular carcinoma, four from metastasis of colon's adenocarcinoma, five for great hemangiomas and the rest for focal liver changes. Right lobectomy was performed in six cases, as well as two trisegmentectomies and two left lobectomies while segmentectomies in the rest. Periopretive mortality occurred in two cases as two patients died because of postoperative thrombosis of vena portae and massive gastrointestinal bleeding. Recidive of malignant tumors was established in five patients after year and in other five till the second year. Benign tumors are without recidives. Later resection is a safe procedure with a considerable selection of patients, with use of latest technical conveniences, application of grafts on branches of vena portae and with routine application of intraoperative ultrasonography. The paper contains diagnostical postulates, surgical techniques and anatomic and morphologic types of resection.

Female↗
PubMed1994

[Use of nuclear medicine technology (radionuclide venography) in detecting a case of suspected ileofemoral phlebothrombosis].

We reviewed a complex nuclear medical method's application for investigating venous circulation of lower extremities--radionuclide venography (RVG) in explaining a case of suspective ileofemoral thrombosis. Suffering from pain and swelling of the right leg, patient T.J. wanted a checkup. After the physical examination, vascular surgeon suspected phlebothrombosis of the right ileofemoral region and immediately sent her to have a radionuclide venography (RVG) (because by Doppler-ultrasonography certain data confirming presence of thrombus in the pelvic region couldn't be gained). On the basis of gathered results vascular surgeon can make a final diagnosis (phlebothrombosis of the right vein femoralis), so that in this case flebography was not necessary. Although performing RVG is complex and requires engagement of experts of different profiles, gathered data are valuable because they cover the shortage of existing diagnostic methods which are most often used in routine work (Doppler-ultrasonography and phlebography). Applying RVG phlebography can be avoided in all patients who are not expected to have operative treatment, and in cases where thrombosis is suspected in deep veins of pelvis, RVG can be performed right away, without Doppler ultrasonography.

Adult↗
PubMed1993

The challenge-phage assay reveals differences in the binding equilibria of mutant Escherichia coli Trp super-repressors in vivo.

The phenotypes of four mutant Escherichia coli Trp repressor proteins with increased activities have been examined in vivo using the challenge-phage assay, an assay based on a positive genetic selection for DNA binding. These proteins, which differ by single amino acid changes from the wild type (Glu13-->Lys, Glu18-->Lys, Glu49-->Lys and Ala77-->Val), require less L-tryptophan than wild-type repressor for activation in vivo, and are super-aporepressors. However, none of the four mutant repressors binds DNA in a corepressor-independent manner. Three of the four mutant repressors (with Glu-->Lys changes) are more active when complexed with tryptophan, and are superholorepressors. Challenge-phage assays with excess tryptophan rank the mutant holorepressors in the same order as determined by binding studies in vitro. Challenge-phage assays with limiting tryptophan reveal additional phenotypic differences among the mutant proteins. These results show that the challenge-phage assay is a robust assay for measuring the relative affinities of specific protein-DNA interactions in vivo.

Bacterial Proteins↗
PubMed1993

Tryptophan super-repressors with alanine 77 changes.

The binding of L-tryptophan to Escherichia coli tryptophan aporepressor enables the holorepressor complex to bind operator DNA tightly. The side chain of residue alanine 77 is located in one of the most flexible regions of Trp repressor, between residues critical for binding DNA. Codon-directed mutagenesis was used to make genes encoding mutant Trp repressors with each of the 19 naturally occurring amino acid changes of Ala77. The 19 mutant proteins are made at the same steady-state levels as wild type. Sensitive challenge phage assays show that 7 of the 19 mutant proteins (Cys, Ser, Val, Leu, Thr, Ile, and Lys) are more active than wild-type protein when tryptophan is limiting in vivo. Among these 7 mutant super-aporepressors, proteins with Cys and Ser changes also are super-holorepressors, because they repress better than wild-type holorepressor when tryptophan is in excess. These results and others suggest that super-aporepressors associate more poorly than wild-type aporepressor with nonspecific DNA. Consistent with this idea, these 7 changes are predicted to disrupt the tertiary structure of aporepressor, but have more limited effects on the structure of holorepressor.

Alanine↗
PubMed1991

Surgical management of extracranial carotid artery aneurysms.

Between 1982 and 1991 we performed eight operations on seven patients with carotid artery aneurysms. Their mean age was 52.8 years (range: 20-67 years). Five aneurysms were atherosclerotic, one was associated with Marfan's syndrome, and two were pseudoaneurysms, one occurring after Dacron patch angioplasty and the other due to tuberculosis. Seven aneurysms were treated electively; one patient underwent an emergency surgical procedure. In one case, the internal carotid artery was ligated. Seven operations were reconstructive. No intraluminal shunt was used. No perioperative deaths occurred. Regressive hemiparesis and ipsilateral Horner's syndrome developed in one patient. The follow-up period ranged from six months to nine and a half years. One patient died of myocardial infarction three months after surgery.

Adult↗
PubMed1990

[The effect of Hatha yoga on poor posture in children and the psychophysiologic condition in adults].

Hatha Yoga's effects on the posture of 15 ten year-old children and also its effects on the psychophysical condition of 15 grown-ups was studied. As symptoms, during the first examination, 12 of the 15 children had head protrusion, 14 had shortened back extensors, all 15 had bent shoulders, relaxation of the frontal abdominal wall and shortened flexors of both the calf and thigh. The condition of all the children was remarkably better after six months of practice, some of the symptoms having completely disappeared (head protrusion, asymmetry of the shoulders, mamillas and hips, shortening of the pectoralis and back extensors), 9 children still had slight to medium relaxation of the frontal abdominal wall, 8 children still had bent shoulders, and 1 child still had shortened calf and thigh extensors. The adults were in a weak or very weak psychophysical condition, they tired easily, they complained of sleep disturbances, fluctuation of emotional state and irritability. After 3 months of practice, the vital capacity of 8 of the adults tested (53.3%) had increased by 435 ml. The time duration of apnoea had lengthened for all of the practicing adults, but with a truly large variation among them (a median of 14%). The deep waist-bend length of all the practicing adults had lengthened by an average of 9.5 cm, and the average length increase for the 3-minute running test was 42 m. All those who practiced, had experienced an alleviation of psychic difficulties.

Adolescent↗
PubMed1990

[Partial heterotopic and total orthotopic transplantation of the liver in dogs].

From 1983 to 1988 on the Department for Experimental Surgery 20 preservations of the liver has been done, with ice cold Euro- Collins and Ringer solutions, either with in situ or with on banch technique after fast expantation. On five dogs standard 55% left hepatectomy has been done and the right side preserved in situ. Partial heterotopic liver transplantation to the right iliac fossa was performed on five dogs. Total vascular exclusion of the liver and extracorporal inierior vena cava and jugular vein by pass with assisted circulation was performed on one dog, without assistance on four dogs. Total orthotopic liver transplantation was performed on two dogs. The surgical team practiced the technique of liver transplantation in experiment and liver resection with in situ technique and on banch technique.

Animals↗
PubMed1989

[Acute pancreatitis and hypertriglyceridemia].

An association between acute pancreatitis and hypertriglyceridemia has long been recognized. The frequency of this association may be as high as 25 per cent. Whether the lipid abnormalities are secondary to acute pancreatitis and therefore temporary or whether they are primary and possibly etiologically involved is unsettled. Most experimental and clinical evidences suggest that hypertriglyceridemia precedes and apparently cause the development of pancreatitis. The mechanism of injury may be mediated through free fatty acids released from the triglycerides. It has recently been identified a group of normotriglyceridemic patients with a previous attack of acute pancreatitis, at least 6 months earlier, who had an impaired clearance of serum triglycerides after an oral fat tolerance test. The clearance of ingested triglycerides was significantly impaired as compared with a control group, irrespective of the presence of diabetes, alcohol consumption or biliary lithiasis. The authors suggested that a triglyceride tolerance test is the only way to detect those patients in whom future attacks of pancreatitis may be precipitated by a diet rich in fat or an alcoholic debauch. In a further study the authors suggested that the abnormal oral fat tolerance test in these patients with previous acute pancreatitis and normotriglyceridemia is secondary to an impaired chylomicron remnants clearance. These findings strongly suggest a relatively common and preexistent defect in lipid metabolism which may be important in the pathogenesis of the disease.

Acute Disease↗