[Reaction mechanism of macrolide 2'-phosphotransferase from Escherichia coli to the 2'-modified macrolide antibiotics].

Reaction mechanism of macrolide 2'-phosphotransferase [MPH(2')] from Escherichia coli to the 2'-modified macrolide antibiotics was analyzed by using microbioassay, nuclear magnetic resonance (NMR) spectrometric assay and mass spectrometry. It was found by microbioassay that the 2'-modified macrolide antibiotics as triacetyloleandomycin (TAO), erythromycin ethyl succinate (EME) and erythromycin estolate were inactivated with adenosine triphosphate (ATP) by MPH(2'). The NMR spectrometric assay for the analysis of the reaction with the 2'-modified macrolide antibiotics and MPH(2') was established using guanosine triphosphate, which was higher reaction rate than ATP, as a cofactor.

Nanoscale packed capillary liquid chromatography-electrospray ionization mass spectrometry: analysis of penicillins and cephems.

A series of seventeen penicillins and cephems (cephalosporins and cephamycins) was examined by electrospray ionization. Separations by nanoscale packed-capillary liquid chromatography, with sub-microliter flow-rates, were performed using methanol-water and acetonitrile-water both containing trifluoroacetic acid gradients. In the on-column analyses, the protonated species usually predominate, and the fragment ions are often present which can be used for confirmation of compound identity.

Purification and characterization of macrolide 2'-phosphotransferase type II from a strain of Escherichia coli highly resistant to macrolide antibiotics.

The resistance mechanism of Escherichia coli BM2506 to macrolides was found to be due to inactivation. Inactivated oleandomycin was identified as oleandomycin 2'-phosphate by thin-layer chromatography. A new type of macrolide-phosphorylating enzyme, macrolide 2'-phosphotransferase type II (MPH(2')II), was detected, purified 95-fold and its enzymological properties investigated.

Application of nanoscale packed capillary liquid chromatography (75 μm id) and capillary zone electrophoresis/electrospray ionization mass spectrometry to the analysis of macrolide antibiotics.

Nanoscale separation techniques, nanoscale packed capillary columns (75 μm id), and capillary zone electrophoresis (CZE), on-line with electrospray mass spectrometry (ESI/MS), were applied to the separation of a series of ten macrolide antibiotics. Both techniques use sub-microliter-per-minute flow rates through the analytical column and therefore require an electrospray probe that incorporates coaxial sheath flow. Positive ion electrospray mass spectra of these compounds yielded mainly protonated molecules.

Thoracic esophageal perforations at a Virginia hospital 1979-1990.

A study was made of all patients who underwent management for distal esophageal perforation at the Fairfax Hospital from September 1979 to September 1990. The study group consisted of 13 patients. Nine were male, four female.

[A specific protein inhibiting membrane permeation of chloramphenicol in Pseudomonas aeruginosa].

A specific protein (MW 18,000) was found using chloramphenicol (CP) base-affinity chromatography of periplasmic-space proteins obtained from an impermeability-type CP-resistant Pseudomonas aeruginosa harboring plasmid kR102. Membrane reconstitution experiments using a liposome system appeared to indicate that the permeability of CP was inhibited by the specific protein.

Purification and characterization of macrolide 2'-phosphotransferase from a strain of Escherichia coli that is highly resistant to erythromycin.

Macrolide 2'-phosphotransferase [MPH(2')] was purified 90-fold from an erythromycin-resistant strain of Escherichia coli, and its enzymatic properties were investigated. MPH(2') is an inducible intracellular enzyme which showed high levels of activity with 14-member-ring macrolides and extremely low levels with 16-member-ring macrolides. The optimum pH for inactivation of oleandomycin was 8.

Nucleotide sequence of the chromosomal gene coding for the aminoglycoside 6-adenylyltransferase from Bacillus subtilis Marburg 168.

Gene aadK of Bacillus subtilis is 855 bp long and codes for aminoglycoside 6-adenylyltransferase.

[Antibacterial activity of (+)-negamycin prepared by a new method].

Antibacterial activity of (+)-negamycin (NGM) prepared by a new method was investigated for some bacteria. The results demonstrated that this antibacterial activity of synthesized NGM was almost the same as compared to that of naturally obtained NGM, and was also effective to Pseudomonas aeruginosa harboring multiple drug resistant plasmid kR102.

Parathyroid adenomas evaluated by Tl-201/Tc-99m pertechnetate subtraction scintigraphy and high-resolution ultrasonography.

Thallium-201/technetium-99m pertechnetate subtraction scintigraphy of the parathyroid glands was performed in a prospective study of 33 patients who had undergone bilateral neck exploration for elevated serum calcium and serum parathyroid hormone levels. In 31 cases, the Tl-201/Tc-99m subtraction technique yielded an overall sensitivity of 81%, specificity of 99%, and accuracy of 94% for identifying solitary parathyroid adenomas. Tl-201/Tc-99m subtraction scintigraphy correctly identified 73% of parathyroid adenomas weighing less than 499 mg, 79% of those weighing 500-1,499 mg, and 100% of adenomas weighing more than 1,500 mg.

Lipopolysaccharide changes in impermeability-type aminoglycoside resistance in Pseudomonas aeruginosa.

Clinical isolates of Pseudomonas aeruginosa were examined for the basis of impermeability-type aminoglycoside resistance. Two apparently related burn isolate strains with high-level (strain 8803) and low-level (strain 13934) gentamicin resistance each had a plasmid. Transformation of the plasmid from either strain to P.

[Comparative study of the activities of beta lactamase inhibitors by nuclear magnetic resonance spectrometry].

Nuclear magnetic resonance (NMR) spectrometry were applied for the measurement of inhibitory activity of some drugs towards beta-lactamase in living cells. From the integrated values of the signals based on 5-H and 6-H of beta-lactam ring or methyl proton of C-2 position of ABPC as substrate, the inhibition dose of 50% (ID50 value) to beta-lactamase activity under the condition containing 10 mg of ABPC was calculated. The ID50 values (mg) of clavulanic acid (CVA), N-formimidoylthienamycin (MK 0787) and dicloxacillin (MDIPC) known as beta-lactamase inhibitor were less than 0.

Mechanism of resistance to some cephalosporins in Staphylococcus aureus.

The mechanism of resistance to some cephalosporins in Staphylococcus aureus strains was investigated with high-pressure liquid chromatography and nuclear magnetic resonance spectrometry. Drug inactivation by penicillinase was found to be the main mechanism of resistance to cefazolin, cephaloridine, and cephalothin in S. aureus.

Hypernephroma with perirenal hemorrhage.

Two cases of hypernephroma with rupture of the renal capsule and localized perirenal hemorrhage are reported. This unusual complication of hypernephroma exhibited a subacute clinical presentation with pain as the major presenting symptom.

Serous papillary neoplasms arising in paramesonephric parovarian cysts. A report of eight cases.

Eight cases of papillary serous cystadenoma arising in paramesonephric parovarian cysts are presented. None of these benign lesions were diagnosed preoperatively as such and were only detected pathologically. In only one case was the tumor-bearing cyst symptomatic owing to its large size.

Subcapsular adipocytic infiltration of the human ovary: a clinicopathologic study of eight cases.

A systematic pathologic study of excised ovaries uncovered 8 cases of microscopic adipocytic infiltration of the subcapsular ovarian cortical stroma among 449 patients subjected to unilateral or bilateral oophorectomy with or without hysterectomy for common gynecologic disorders. As this process was only detected in the routine paraffin sections, no fresh tissue was available for ultrastructural, histochemical and biochemical investigations. Its differential diagnosis is presented, and the possible role of obesity is discussed in its causation.

Nuclear magnetic resonance spectrometric assay of beta-lactamase.

Beta-Lactam antibiotics and the crude enzyme were mixed in deuterium oxide and placed in a nuclear magnetic resonance tube. The change of the nuclear magnetic resonance spectrum during the enzymatic reaction was then analyzed to determine beta-lactamase activity. By using beta-lactam antibiotics such as penicillins, cephalosporins, and cephamycins as substrates, a comparison of the beta-lactamase activities was made between the nuclear magnetic resonance spectrometric assay and the iodometric assay.