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Biomedical subjects

M Melzer

Publications and source records attributed to M Melzer.

At least 19 recordsLinked to original sources
PubMed1994

Characterization of polyprenyldiphosphate: 4-hydroxybenzoate polyprenyltransferase from Escherichia coli.

Polyprenyldiphosphate: 4-hydroxybenzoate polyprenyltransferase (4-HB polyprenyltransferase) is a key enzyme in ubiquinone biosynthesis in E. coli, encoded by the gene ubiA. By overexpression of ubiA and isolation of the membrane fraction, the enzyme was enriched approx. 3000-fold and characterized. The enzyme is membrane-bound and could not be solubilized by hypotonic buffer or detergent treatment. The enzymatic activity is optimal at pH 7.8 and depends on the presence of magnesium ions. Geranyldiphosphate (GPP), all-trans-farnesyldiphosphate (FPP) and all-trans-solanesyldiphosphate (SPP) are accepted as side chain precursors. The apparent Km values for these substances are are 254 microM, 22 microM and 31 microM, respectively. No reaction was observed with omega-t2-c5-octaprenyldiphosphate, in which five double bounds have cis-configuration. The reaction is stimulated by 0.01% CHAPS, but strongly inhibited by sodiumdeoxycholate, Tween 80 and Triton X-100. The amino acid sequence shows striking similarities to 4-HB hexaprenyltransferase from yeast. Sequence homologies to other prenyltransferases are discussed.

Alkyl and Aryl Transferases↗
PubMed1992

Ubiquinone biosynthesis. Cloning of the genes coding for chorismate pyruvate-lyase and 4-hydroxybenzoate octaprenyl transferase from Escherichia coli.

Chorismate pyruvate-lyase activity was detected in extracts of Escherichia coli. 4-Hydroxybenzoate was identified as the product of the enzymatic reaction by chemical derivatization and GC-MS analysis. The ubiC gene, coding for the chorismate pyruvate-lyase, was cloned and sequenced. The molecular weight of the gene product was calculated as 18,776 Da and confirmed by expression of the protein in E. coli minicells. The ubiA gene, coding for the 4-hydroxybenzoate octaprenyl transferase, was identified by sequence homology and complementation of a ubiA- strain. It is located directly downstream of ubiC in a typical operon structure.

Alkyl and Aryl Transferases↗
PubMed1984

Blunt abdominal trauma with unrecognized urinary tract injury.

We report three cases of serious renal injuries due to blunt abdominal trauma within the context of multiple organ trauma. The renal involvement was not initially suspected, with resulting serious consequences. We suggest that infusion pyelography be performed prior to or shortly after surgery in all cases with extensive abdominal trauma. A retroperitoneal hematoma on explorative laparotomy in cases of multiple trauma should raise the suspicion of a concomitant serious renal injury, and an immediate diagnostic investigation should be conducted.

Abdominal Injuries↗
PubMed1981

Restriction endonuclease EcaI from Enterobacter cloacae.

Restriction endonuclease EcaI obtained from Enterobacter cloacae DSM30056 recognizes the group of heptanucleotide palindromes 5'-G[unk]G-T-N-A-C-C-3', and on cleavage (arrow) produces fragments with 5'-terminal pentanucleotide extensions. It is identical in specificity with restriction endonuclease BstEII from Bacillus stearothermophilus ET.

Base Sequence↗
PubMed1981

Comparison among patterns of macromolecular synthesis in Escherichia coli B/r at growth rates of less and more than one doubling per hour at 37 degrees C.

In Escherichia coli B/r, the relationship between the patterns of chromosome replication and of synthesis of envelope components differs at various growth rates. At growth rates greater than 1.0 doubling per h at 37 degrees C, the average mass and age at initiation of rounds of chromosome replication are similar to those at increase in incorporation of precursors into a major outer membrane protein and phosphatidylethanolamine. At growth rates less than 1.0 doubling per h at 37 degrees C the average mass and age at increase in the synthesis of these envelope components differ from those at initiation of chromosome replication. The average cell mass per chromosomal origin at initiation of rounds of chromosome replication is not a constant and varies between growth rates greater and less than 1.0 doubling per h.

Bacterial Proteins↗
PubMed1977

Crossed renal ectopia: clinical and radiological findings in 22 cases.

The clinical and radiological features of 22 patients with crossed ectopic kidneys are reported, including a case with unusual mobility of an unfused ectopic kidney. In some cases the anomaly was an incidental finding. However, complications were frequent and included seven hydronephrotic and three non-functioning kidneys, two of the latter were found to be obstructed by a calculus. Vesico-ureteral reflux was demonstrated in three of the five children in whom the examination was performed. Anomalous blood supply was present in all patients who underwent renal arteriography or surgery. Skeletal anomalies were present in 11 patients, one of whom had in addition coarctation of the aorta, and another atrial septal defect and anal atresia.

Adolescent↗
PubMed1976

The status of the urinary tract in a survey of 92 cases with neurogenic bladder.

Since 1973 intermittent catheterisation was introduced in our centre and this practically eliminated pathology of the urethra. More than half of the patients had a high and complete lesion. It is our impression that 5 years following injury more than half of the patients preserved a normal upper urinary tract; however, only 39 of the 92 patients had a follow-up of over 5 years. Nephrolithiasis was rare in comparison to other reports in spite of belonging to the stone belt area. Complications of the lower urinary tract including a 10 per cent incidence of vesico-ureteric reflux were compatible with other series. Narrowing of the external sphincter on voiding cystogram should be substantiated by a profile pressure record. One female patient is a candidate for ileal conduit. Most of the patients have some form of erection but the data on ejaculation should be accepted with reserve. Two patients in this series died more than 10 years after injury, one due to a myocardial infarction and the other due to chronic renal failure following secondary amyloidosis.

Adolescent↗
PubMed1975

Pyonephrosis due to salmonella cholerae-suis variant kunzendorf.

A patient with unilateral infection of the kidney due to Salm. cholerase-suis is presented. Long-term treatment with ampicillin was of no avail. Nephrectomy terminated the infection. The extirpated kidney showed severe obstruction, stones and tissue damage.

Abscess↗
PubMed1975

The management of urologic complications after kidney transplantation.

Urologic complications occurred in four (20%) of 20 kidney transplants performed in 18 patients. The complications encountered were acute hemorrhage from the distal end of the ureter, a calyceal fistula, a ureteral stricture with associated fungus infection, and obstructive uropathy. In two of the four cases it was necessary to sacrifice the transplant.

Acute Disease↗