Dynamics of methyl groups in proteins as studied by proton-detected 13C NMR spectroscopy. Application to the leucine residues of staphylococcal nuclease.

This paper describes the application of recently developed nuclear magnetic resonance (NMR) pulse sequences to obtain information about the internal dynamics of isotopically enriched hydrophobic side chains in proteins. The two-dimensional spectra provided by the pulse sequences enable one to make accurate measurements of nuclear Overhauser effects (NOE) and longitudinal (T1) and transverse (T2) relaxation times of enriched methyl carbons in proteins. Herein, these techniques are used to investigate the internal dynamics of the 11 leucine side chains of staphylococcal nuclease (SNase), a small enzyme having Mr = 16.

The pathology of the posterior root ganglia in AIDS and its relationship to the pallor of the gracile tract.

The spinal cord and the thoracic and lumbar posterior root ganglia (PRGs) of 14 HIV-positive men and 7 age- and sex-matched controls were studied by routine histology, morphometric analysis of the number of nodules of Nageotte (nN) and the diameters of sensory ganglion cells, immunohistochemistry and in situ hybridization. In 7 patients (2 of whom had evidence of cytomegalovirus ganglionitis) there were increased numbers of nN and diffuse, mild infiltration with CD45R+ T lymphocytes; no B lymphocytes were observed. Macrophages were increased in number in all cases.

Comparison of N-acetylglucosaminyltransferase V activities in Rous sarcoma-transformed baby hamster kidney (RS-BHK) and BHK cells.

Recent studies have demonstrated that Rous sarcoma virus-transformed baby hamster kidney (RS-BHK) cells express twofold higher levels of those N-linked oligosaccharides that contain the sequence [GlcNAc-beta(1,6)Man (1,6)] compared to nontransformed parental BHK cells (Pierce and Arango, J. Biol.Chem.

Activity of UDP-GlcNAc:alpha-mannoside beta(1,6)N-acetylglucosaminyltransferase (GnT V) in cultured cells using a synthetic trisaccharide acceptor.

N-acetylglucosaminyltransferase V activity has been measured under saturating conditions in the extracts of seven cultured cell lines using as substrates, UDP-[3H]-GlcNAc and a synthetic 8-methoxylcarbonyloctyl trisaccharide. The unreacted sugar-nucleotide and its breakdown products were separated from the radiolabeled tetrasaccharide product by reverse-phase chromatography. Enzyme activity was present in six of the cell lines, which were derived originally from either human, mouse, or hamster tissues, with the highest activity in mouse lymphoma BW5147 cells.

Rous sarcoma virus-transformed baby hamster kidney cells express higher levels of asparagine-linked tri- and tetraantennary glycopeptides containing [GlcNAc-beta (1,6)Man-alpha (1,6)Man] and poly-N-acetyllactosamine sequences than baby hamster kidney cells.

The alterations in complex-type N-linked oligosaccharides that can occur when an animal cell line is transformed by two dissimilar viruses were examined by comparing the N-linked oligosaccharides of baby hamster kidney (BHK) cells, metabolically radiolabeled with [2-3H]mannose, to the same class of oligosaccharides from BHK cells separately transformed by Rous sarcoma virus (RS-BHK), an RNA retrovirus, and polyoma virus (PY-BHK), a DNA papovavirus. Based on experiments that utilized serial lectin affinity chromatography, glycosidase digestions, and methylation analyses, both RS-BHK and PY-BHK cells demonstrated a significant increase in the relative amounts of tri- and tetraantennary complex-type N-linked oligosaccharides containing the branching sequence, [GlcNAc-beta(1,6)Man-alpha(1,6)Man], compared to the nontransformed BHK cells. In addition, almost all of the poly-N-acetyllactosamine sequence, [GlcNAc-beta(1,3)-Gal-beta(1,4)], was expressed on the tri- and tetraantennary N-linked oligosaccharides from BHK and RS-BHK cells that contain the sequence, [GlcNAc-beta(1,6)Man-beta(1,6)Man].

Separation of metabolically radiolabeled O-methylmannitols and O-methylfucitol by reverse-phase high-performance liquid chromatography: applications to animal cell oligosaccharide structural analysis.

Reverse-phase high-performance liquid chromatography was utilized to separate efficiently and rapidly a standard mixture of various radiolabeled O-methylated mannitols and O-methylfucitol commonly encountered when vertebrate asparagine-linked oligosaccharides are subjected to permethylation, hydrolysis, and reduction with NaBH4. The following reduced, radioactive O-methylhexitols were resolved: 2,4-, 3,4-, and 3,6-di-O-methylmannitols; 3,4,6-tri-O-methylmannitol, 2,3,4-tri-O-methylfucitol, and 2,3,4,6-tetra-O-methylmannitol. To demonstrate the utility of this separation method in the analysis of metabolically radiolabeled asparagine-linked oligosaccharides, mouse lymphoma BW 5147 cells were metabolically radiolabeled with [2-3H]mannose and their glycopeptides prepared by Pronase digestion and fractionated by serial chromatography on immobilized lectins.

Promoting breast feeding: a national perspective.

The promotion of breast feeding is 1 of 17 nutrition objectives set out in the Public Health Service's Objectives for the Nation. Trends in breast feeding for the last 30 years are reviewed. While the proportion of mothers breast feeding in the overall American population has been steadily increasing, there is still much to be accomplished in order to meet the 1990 national breast feeding objective.

Transmission of toxoplasmosis by renal transplant.

Two renal allograft recipients who had received their organs from the same cadaver donor developed acute toxoplasmosis shortly after transplantation. Neither of the recipients had serologic evidence of previous exposure to Toxoplasma gondii at the time of surgery, but the donor had a positive indirect fluorescent antibody test. One of the recipients died during the fourth week, and multiorgan involvement with toxoplasmosis was demonstrated at autopsy.

[Dental education oriented to various socioeconomic conditions in Panama].

The current system of instruction in the School of Dentistry of the University of Panama is described. The object of the system is to prepare professional people capable of blending biological, techological, and social principles and applying them in different models of dental care for the solution of individual and collective oral health problems. The students take their clinical training in the metropolitan area (clinics on campus and in Santo Tomás Hospital) in the heavily populated rural area (the community hospital and primary schools), and in the sparsely populated countryside (where they work with teams of three auxiliaries in prevention programs for schoolchildren and programs of care for teachers and lend support to community activities).

Effectiveness of two new cephalosporins, cephazolin and cephapirin, administered intermittently in acute and chronic osteomyelitis in children.

Ten patients were treated, most of pre-school age, with acute osteomyelitis, produced by Staphylococcus aureus and Salmonella, having evolved for approximately one week, with sodium cephazolin at doses of 60 mg/kg/day intramuscularly in two daily injections for the first seven days and then in a single dose every twenty-four hours for four to seven weeks. Nine of ten patients were asymptomatic six months after this treatment. The patient who manifested chronic signs at the end of six weeks of therapy continued to be treated with three weekly injections of the same drug at an equal dose until the completion of six months, at the end of which he was asymptomatic.