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A Leiser

Publications and source records attributed to A Leiser.

At least 19 recordsLinked to original sources
PubMed1998

Cloning, sequencing, expression, and insertional inactivation of the gene for the large subunit of the coenzyme B12-dependent isobutyryl-CoA mutase from Streptomyces cinnamonensis.

Purification of the coenzyme B12-dependent isobutyryl-CoA mutase (ICM) from Streptomyces cinnamonensis gave a protein of approximately 65 kDa by SDS-polyacrylamide gel electrophoresis, whose gene icmA was cloned using sequences derived from tryptic peptide fragments. The gene encodes a protein of 566 residues (62, 487 Da), with 43-44% sequence identity to the large subunit of methylmalonyl-CoA mutase (MCM) from S. cinnamonensis and Propionibacterium shermanii. Targeted disruption of the icmA gene yielded an S. cinnamonensis mutant devoid of ICM activity. The IcmA protein is approximately 160 residues shorter than the large subunit of the bacterial MCMs, corresponding to a loss of the entire C-terminal coenzyme B12 binding domain. The sequence of the (beta/alpha)8-barrel comprising residues A1-A400 in P. shermanii MCM is highly conserved in IcmA. The protein was produced in Streptomyces lividans and Escherichia coli with an N-terminal His6 tag (His6-IcmA), but after purification His6-IcmA showed no ICM activity. In the presence of coenzyme B12, protein from S. lividans and S. cinnamonensis of approximately 17 kDa by SDS-polyacrylamide gel electrophoresis could be selectively eluted with His6-IcmA from a Ni2+ affinity column. After purification, this small subunit showed no ICM activity but gave active enzyme when recombined with coenzyme B12 and IcmA or His6-IcmA.

Amino Acid Sequence↗
PubMed1998

Video-assisted thoracoscopic pericardial fenestration for loculated or recurrent effusions.

OBJECTIVE: The validity of video-assisted thoracoscopic pericardial fenestration was prospectively assessed for loculated effusions. effusions previously treated by percutaneous catheter manoeuvres and those with concurrent pleural diseases. METHODS: Inclusion criteria consisted of echocardiographically documented pericardial effusions requiring diagnosis or relief of symptoms and recurrent effusions after failed percutaneous drainage and balloon pericardiotomy. Pre-operative CT-scan was used to delineate additional pleural pathology and to determine the side of intervention. All patients were followed clinically and by echocardiographic examination 3 months post-operatively. RESULTS: Twenty-four patients underwent thoracoscopic pericardial fenestration with 11 patients (54%) being previously treated by percutaneous catheter drainage, balloon pericardiotomy or subxyphoidal fenestration. Pre-operative echocardiography revealed septation and loculation in 18 patients (72%). Additional pleural pathology was identified on CT scan in 12 patients (50%) and talc pleurodesis was performed in six patients, all suffering from malignant pleural effusion. The mean operation time was 45 min (range 30-60 min) with no complications being observed. All patients were followed 3 months post-operatively by clinical and echocardiographic examination; relief of symptoms was achieved in all patients but echocardiography showed a recurrence in one patient (4%). Another recurrence was found by echocardiography after a mean follow-up time of 33 months in the 12 patients suffering from a non-malignant pericardial effusion. No recurrence of pleural or pericardial effusion was observed in the subset of patients with talc pleurodesis. CONCLUSION: Video-assisted thoracoscopic pericardial fenestration is safe and effective for loculated pericardial effusions previously treated by percutaneous drainage manoeuvres and those with concomitant pleural disease.

Adolescent↗
PubMed1998

Comparison of two bowel preparations for colonoscopy: sodium picosulphate with magnesium citrate versus sulphate-free polyethylene glycol lavage solution.

OBJECTIVES: Adequate preparation of the bowel is essential for accurate colonoscopic examination. We compared colonic preparation with sodium picosulphate plus magnesium citrate (SPS-Mg) with sulphate-free polyethylene glycol electrolyte lavage (PEG-EL) solution before colonoscopy, for quality of bowel cleansing, patient discomfort, and side effects. METHODS: Sixty-eight consecutive patients were randomly assigned to receive either 3 sachets of SPS-Mg (16.5 g each) (n = 39) or 3 L of PEG-EL (n = 29) on the day before colonoscopy. Shortly before the procedure each patient was interviewed to determine the degree of discomfort (1 = none or mild, 2 = moderate, 3 = severe) and side effects. The quality of bowel cleansing was graded by a gastroenterologist who was unaware of the method of preparation (from 1 = poor to 4 = excellent). RESULTS: Of the 29 PEG-EL patients, four (14%) did not complete the preparation because of side effects. The degree of discomfort was significantly greater with PEG-EL (mean score, 2.3 +/- 0.7) than with SPS-Mg (mean score, 1.4 +/- 0.5; p < 0.01). Nausea and vomiting were significantly more common in the PEG-EL group (38% vs 13%; p < 0.05). Using intention-to-treat analysis, bowel cleansing proved to be significantly better with SPS-Mg than with PEG-EL (mean score +/- SD, 3.05 +/- 0.9 and 2.57 +/- 1.0, respectively; p = 0.036). CONCLUSIONS: Colonic preparation with SPS-Mg is better tolerated, associated with significantly fewer side effects, and results in higher quality bowel cleansing than preparation with PEG-EL.

Adult↗
PubMed1997

[Blunt abdominal trauma with lesion of the abdominal aorta--a case report].

A 58-year old lady, involved in a head-on motor vehicle crash suffered a severe intestinal injury associated with an intimal flap lesion of the distal abdominal aorta. Thrombotic occlusion of the aortic bifurcation with clinical evidence of lower extremity ischemia was noted. The management of blunt injury to the abdominal aorta is discussed with special regard to placing prosthetic material in a potentially infected field.

Abdominal Injuries↗
PubMed1996

Cloning, sequencing, overexpression in Escherichia coli, and inactivation of the valine dehydrogenase gene in the polyether antibiotic producer Streptomyces cinnamonensis.

The catabolism of branched chain amino acids, especially valine, appears to play an important role in furnishing building blocks for macrolide antibiotic biosynthesis. To determine for the first time the importance of valine dehydrogenase (vdh) in polyether antibiotic biosynthesis, the vdh gene from Streptomyces cinnamonensis has been cloned and sequenced. The enzyme (M(r)37,718 Da) has been produced in large amounts in an active form in the E. coli cytoplasm using a T7 RNA-polymerase expression system. Upon inactivation of the gene in S. cinnamonensis by a double-crossover mechanism, a hyg::vdh mutant was isolated that was devoid of vdh activity. Upon growth in chemically defined media, as well as a complex medium optimised for monensin production, the mutant and wild-type grew equally well and reached the same levels of monensin production. In both strains a valine transaminase activity could be detected that provides an alternative route for converting valine into 2-oxoisovaleric acid. The results show that vdh is not essential for normal growth of S. cinnamonensis, and its inactivation does not significantly affect normal levels of monensin production in this strain.

Amino Acid Oxidoreductases↗
PubMed1996

Helicobacter pylori infection and blood groups.

OBJECTIVES: Bacterial attachment is a prerequisite for colonization of the gastric epithelial surface. Recently, it was demonstrated that the receptor for Helicobacter pylori is the blood group antigen Lewis b, which is exposed only in blood group O. We prospectively examined the prevalence of blood groups in H. pylori-positive and -negative patients. To avoid a genetic bias, we compared blood group prevalence of our patients with the general population of Israel. METHODS: In the 187 consecutive patients we studied, in addition to regular upper endoscopy, H. pylori status and blood group. Exposure to H. pylori was diagnosed when the results of two or more of three methods were found to be positive. RESULTS: Exposure was found in 123 patients and 64 negative. The groups were similar in average age and origin, and no significant difference was demonstrated for blood group. Blood group distribution between any given origin was not significantly different in our patients and in a sample of 182,701 blood donors. CONCLUSIONS: Positivity for H. pylori was not associated with blood group O. Our observation does not support the conclusion that the receptor for H. pylori in the gastric mucosa is the blood group antigen Lewis b.

Adolescent↗
PubMed1994

Three years' experience in video-assisted thoracic surgery (VATS) for spontaneous pneumothorax.

In a prospective study (June 1990 to June 1993), 79 patients were treated for spontaneous pneumothorax by video-assisted thoracoscopic methods with regular follow-up. The observation time was from 3 to 36 months (mean 19.6 months) and was more than 24 months in 27 patients. In 57 patients spontaneous pneumothorax was primary and in 22 secondary. The 53 male and 26 female patients were aged between 17 and 87 years (mean 37 years). Twenty-one patients were treated thoracoscopically for first episode, 22 for persistent pneumothorax (> 7 days), and 36 for a recurrence. Endoscopic examination failed to reveal any lung alteration in four patients (5.1%), and treatment then consisted of simple drainage. Leaks were sealed 26 times by means of a Roeder loop with local anesthesia and 14 times by wedge resection with endotracheal anesthesia and one-lung ventilation; 34 patients were treated by pleurectomy. No deaths occurred. Surgical morbidity was 3.8%, and the postoperative complication rate was 5.1%. One patient was excluded from the follow-up study after conversion to a thoracotomy for control of arterial bleeding. We noted six recurrences; four occurred in the first 21 days and three after ligation of the leak with a Roeder loop. We conclude that video-assisted thoracoscopic treatment of spontaneous pneumothorax by wedge resection and pleurectomy has a recurrence-free rate of 93.8% (45/48) and is therefore an effective treatment for all forms of spontaneous pneumothorax.

Adolescent↗
PubMed1993

The DNA-binding properties of an artificial 42-residue polypeptide derived from a natural repressor.

Bacteriophage 434 repressor recognizes the operator sequences ACAAG and ACAAT. As the same or similar sequences occur in the enhancer region of HIV-1, 434 repressor was a potential HIV enhancer-binding protein. We found that the interaction of the DNA-binding domain of 434 repressor with a 57-bp HIV enhancer DNA was very weak whereas a 42-residue construct, comprising the recognition helix and four copies of a positively charged segment of the repressor, bound strongly. The results of footprint and cell-free in vitro transcription studies showed that the 42-residue peptide bound preferably to the enhancer region of HIV-1 and acted as an artificial repressor. Replacement of an essential glutamine of the recognition helix by glutamic acid resulted in a partial shift of the sequence specificity of the 42-residue peptide.

Amino Acid Sequence↗
PubMed1993

Cloning, sequencing, and expression of the gene encoding methylmalonyl-coenzyme A mutase from Streptomyces cinnamonensis.

In streptomycetes, the conversion of succinyl-coenzyme A (CoA) into methylmalonyl-CoA, catalyzed by methylmalonyl-CoA mutase, most likely represents an important source of building blocks for polyketide antibiotic biosynthesis. In this work, the structural gene for methylmalonyl-CoA mutase from Streptomyces cinnamonensis was cloned by using a heterologous gene probe encoding the mutase from Propionibacterium shermanii. A 5,732-bp fragment was sequenced, within which four open reading frames were identified on one DNA strand. The two largest (mutA and mutB) overlap by 1 nucleotide and encode proteins of 616 and 733 residues showing high amino acid sequence similarities to each other and to methylmalonyl-CoA mutases from P. shermanii and mammalian sources. The transcriptional start of the mutA-mutB message, determined by S1 mapping, coincides with the first nucleotide of the translational start codon. Evidence that these two open reading frames encode a functional mutase in S. cinnamonensis was obtained by subcloning and expression in Streptomyces lividans TK64. The mutA and mutB gene products were detected in Western blots (immunoblots) with mutase-specific antibodies and by direct detection of mutase activity with a newly developed assay method. The methylmalonyl-CoA mutase was unable to catalyze the conversion of isobutyryl-CoA into n-butyryl-CoA, another closely related adenosylcobalamin-dependent rearrangement known to occur in S. cinnamonensis.

Amino Acid Sequence↗
PubMed1992

Familial chronic recurrent pancreatitis in identical twins. Case report and review of the literature.

Familial presentation of chronic recurrent pancreatitis in childhood is rare. The etiology of this illness is obscure, and its hereditary properties are not well defined. Simultaneous occurrence of chronic recurrent pancreatitis in identical twins with the same clinical presentation and similar typical pancreatographic abnormalities is exceptional. Twin sisters, aged 9 years, were admitted to the hospital because of recurrent attacks of pancreatitis. Ultrasound examination revealed an enlarged irregular pancreatic duct in both girls, and endoscopic retrograde cholangiopancreatography showed a distorted duct with multiple strictures and dilatations similar to a "chain of lakes" pattern. Both patients underwent longitudinal pancreatojejunostomy within a month. The therapeutic regimen and preoperative and surgical treatment of such patients are discussed, as is the optimal timing of intervention.

Child↗
PubMed1991

Esophageal involvement in pemphigus vulgaris: a clinical, histologic, and immunopathologic study.

Eleven newly diagnosed patients and one patient with pemphigus vulgaris who relapsed underwent endoscopy of the upper gastrointestinal tract. Three patients had blisters or erosions and two had longitudinal lines of erythema in the esophageal mucosa. In four patients histopathologic examination showed findings of pemphigus vulgaris but direct immunofluorescence was positive in all patients. This study demonstrates that the immunopathologic disturbance in pemphigus vulgaris involves the entire length of the esophagus, although only some patients have clinical or histologic involvement. To the best of our knowledge this is the first histopathologic and direct immunofluorescence study of esophageal involvement in patients with untreated pemphigus vulgaris.

Adult↗
PubMed1991

Treatment of esophageal varices: low versus high dose of 5% ethanolamine oleate.

Twenty-four patients, undergoing sclerotherapy for esophageal varices, were injected with 10-20 ml of ethanolamine oleate 5% in the first treatment session (group A). Fourteen patients were injected with 40 ml of the same sclerosant in the first session (group B). Retrospective analysis was carried out to evaluate the efficacy and safety of the two doses. Variceal eradication was achieved in group B in significantly fewer sclerotherapy sessions. Rebleeding occurred in 16% of patients in group A, compared with no rebleeding in group B. There was no significant difference in the incidence of various complications. We conclude that the use of 40 ml of 5% ethanolamine oleate in the first session is more effective and as safe as the use of 20 ml of the same sclerosant.

Adolescent↗
PubMed1986

Beneficial effect of colchicine in a case of sclerosing cholangitis.

A patient with ulcerative colitis and primary sclerosis cholangitis confirmed by liver biopsy and endoscopic retrograde cholangiography presented with severely altered liver function tests. A month of steroid treatment for the colitis symptoms had no effect on the liver function tests, and colchicine, 1 mg/day, was added. After 3 months of this combined treatment, improvement of the liver function tests was noted and progressed to complete normalization of all liver function tests at the end of a 2-year period of follow-up. On further follow-up, the patient remained asymptomatic and with normal liver function tests for an additional 3 years. Further controlled studies would be worthwhile to evaluate the possibility of treatment of primary sclerosis cholangitis with colchicine with or without steroids.

Adult↗
PubMed1986

Primary duodenal carcinoid with malignant carcinoid syndrome: a case report.

Primary duodenal carcinoid causing a malignant carcinoid syndrome is rare. Herein a case is reported. In view of this case and a review of the literature, the carcinoid syndrome is almost pathognomonic of massive liver metastasis or involvement of organs whose venous drainage is not through the portal system. The right upper quadrant abdominal pains accompanied by symptoms that resemble even part of the carcinoid syndrome should initiate the investigational process including proximal gastrointestinal endoscopy to avoid delay in diagnosis of duodenal carcinoid.

Carcinoid Tumor↗
PubMed1985

Mesenteric venous infarction presenting as an upper GI bleeding and diagnosed by upper GI endoscopy.

A case of primary mesenteric vein thrombosis with extensive small bowel infarct beginning at the ligament of Treitz presented as upper gastrointestinal bleeding. Although endoscopy of the upper GI tract disclosed erosive gastritis this finding was considered insufficient to explain the hematemesis; therefore the endoscope was advanced further until a necrotic and aperistaltic-looking mucosa was found in the area of the ligament of Treitz. This paper describes the endoscopic picture of necrotic duodenal mucosa, and stresses the importance of a deeper examination into the duodenum when a clear-cut cause for the bleeding is not found in the stomach or duodenal bulb.

Adolescent↗
PubMed1981

Evaluation of prajmalium-induced cholestasis by immunologic tests.

Cholestatic jaundice developed in four patients after the administration of prajmalium bitartrate. The clinical, histologic, ultrastructural, and immunologic findings were determined. In all patients, the clinical and morphologic features indicated idiosyncrasy. Two antibodies distributed in a granular pattern along the bile canaliculi were detected by immunofluorescence in all patients. In one patient, autoimmune markers were found in the serum, and in two instances, the migration-inhibition factor assay against the offending drug was found to be positive. The data support the concept that immunologic processes may participate in the production of the cholestatic syndrome.

Aged↗