Depression of hydrogen peroxide dependent killing of schistosomula in vitro by peritoneal exudate cells from Schistosoma mansoni infected mice

Peritoneal exudate cells from mice infected with Schistosoma mansoni (S-PEC) can kill a small proportion of schistosomula in vitro in the presence of immune serum. S-PEC produce a low level of respiratory burst. However, schistosomula mortality in their presence is not reduced when exogenous antioxidants are added, suggesting that with S-PEC, oxidative killing may not be important. Hydrogen peroxide (H2O2) and superoxide production by S-PEC, and cells from Bacillus Calmette-Guerin (BCG) and thioglycollate (THGL) injected mice, nonspecifically stimulated with opsonized zymosan, were measured. Levels of H2O2 produced by S-PEC were significantly lower than BCG or THGL PEC, and were below the threshold for schistosomula killing. This correlated with lower levels of cell-mediated killing of schistosomula in vitro by S-PEC than by BCG-PEC. Superoxide levels, however, were similar between the 3 cell populations. It therefore appears that the efficiency of PEC to kill schistosomules in vitro correlates with H2O2 rather than superoxide levels. It was found that there was a sharp concentration threshold in H2O2 mediated killing of schistosomula. A depression in the levels of H2O2 produced may be a mechanism by which the parasite can partially evade the host immune system.

Amino acid sequence of the bacterioferritin (cytochrome b1) of Escherichia coli-K12

The complete amino acid sequence of bacterioferritin (cytochrome b1) from Escherichia coli-K12 has been derived from the nucleotide sequence of the cloned gene. It comprises 158 amino acid residues giving an Mr of 18,495. The identity of the gene product was confirmed by an 87 residue N-terminal sequence obtained from the purified protein, but it differs significantly from much of the previously published partial amino acid sequence (1). Secondary structure prediction indicates a high alpha-helical content consistent with a 4-helix-bundle conformation. The fully assembled bacterioferritin molecule comprising 24 identical subunits and 12 haem moieties is a tetracosamer with an Mr of approximately 452,000.

Molecular size and symmetry of the bacterioferritin of Escherichia coli. X-ray crystallographic characterization of four crystal forms

X-ray crystallographic data from four crystal forms of Escherichia coli bacterioferritin show that the molecule has a diameter in the range 119 to 128 A. Molecules are composed of 24 subunits arranged in 432 symmetry. In both size and symmetry the molecule resembles ferritin from eukaryotes. The four crystal forms are monoclinic, space group P2(1) with unit cell dimensions a = 118.7 A, b = 211.6 A, c = 123.3 A and beta = 119.1 degrees; orthorhombic, C222(1), a = 128.7 A, b = 197.1 A, c = 202.8 A; tetragonal, P4(2)2(1)2, a = b = 210.6 A, c = 145.0 A and cubic, I432, a = 146.9 A.

Nucleotide sequence analysis of the purEK operon encoding 5'-phosphoribosyl-5-aminoimidazole carboxylase of Escherichia coli K-12

5'-Phosphoribosyl-5-aminoimidazole (AIR) carboxylase (EC 4.1.1.21) catalyzes step 6, the carboxylation of AIR to 5'-phosphoribosyl-5-aminoimidazole-4-carboxylic acid, in the de novo biosynthesis of purine nucleotides. As deduced from the DNA sequence of restriction fragments encoding AIR carboxylase and supported by maxicell analyses, AIR carboxylase was found to be composed of two nonidentical subunits. In agreement with established complementation data, the catalytic subunit (deduced Mr, 17,782) was encoded by the purE gene, while the CO2-binding subunit (deduced Mr, 39,385) was encoded by the purK gene. These two genes formed an operon in which the termination codon of the purE gene overlapped the initiation codon of the purK gene. The 5' end of the purEK mRNA was determined by mung bean nuclease mapping and was located 41 nucleotides upstream of the proposed initiation codon. The purEK operon is regulated by the purR gene product, and a purR regulatory-protein-binding site related to the sequences found in other pur loci was identified in the purEK operon control region.

Nucleotide sequence and analysis of the purA gene encoding adenylosuccinate synthetase of Escherichia coli K12

Adenylosuccinate synthetase (EC 6.3.4.4), encoded by the purA gene of Escherichia coli K12, catalyzes the synthesis of adenylosuccinate (SAMP) from IMP, the first committed step in AMP biosynthesis. The E. coli K12 purA gene and flanking DNA was cloned by miniMu-mediated transduction, and the nucleotide sequence was determined. The mature SAMP synthetase subunit, as deduced from the DNA sequence, contains 427 amino acid residues and has a calculated Mr of 47,277. The size of the purA mRNA was determined by Northern blotting to be approximately 1.5 kilobase pairs. The 5'-end of the purA mRNA was identified by primer extension and is located 23 nucleotides upstream of the ATG translational initiation codon. Comparison of the purA control region with the guaBA control region revealed a common region of dyad symmetry which may suggest mutual elements of regulation. The purA control region did not resemble the control regions of the other known pur loci.

Antimicrobial susceptibility patterns of Nocardia asteroides

Testing of the susceptibility to 12 antimicrobial agents, including beta-lactams, aminoglycosides, ciprofloxacin, and erythromycin, was performed by broth microdilution on 78 consecutive clinical isolates of Nocardia asteroides. Surprisingly, a limited number of patterns of susceptibility were identified that included all drug classes, with 95% of isolates exhibiting one of five patterns. One group (17%) exhibited resistance to the broad-spectrum cephalosporins, one group (18%) was susceptible to both ampicillin and erythromycin, one group (17%) was susceptible to ampicillin and carbenicillin but intermediate in susceptibility to imipenem, and the most common group (35%) was resistant to ampicillin but susceptible to the broad-spectrum cephalosporins and imipenem. The most active parenteral agents were amikacin (95%), imipenem (88%), ceftriaxone (82%), and cefotaxime (82%), while the most active oral agents were the sulfonamides (100%), minocycline (100%), and ampicillin (40%). Additional studies are needed to determine whether differences in beta-lactamases relate to varying beta-lactam resistance and whether taxonomic differences that correlate with the different susceptibility groups can be identified.

The identity of Escherichia coli bacterioferritin and cytochrome b1

Two different procedures were used to prepare pure samples of 'cytochrome b1' (column chromatography) and 'bacterioferritin' (immunoprecipitation) from Escherichia coli K-12 strain CA265. Both were crystallized, and X-ray-crystallographic data were compared with those from the bacterioferritin of E. coli strain W3300 used as a standard. We conclude that 'cytochrome b1' and 'bacterioferritin' are identical.

Survey of computer programs for diabetes management and education

A number of computer software programs have been developed to facilitate diabetes management and education for health profes sionals and people with diabetes. Some programs calculate insulin dosages and dietary require ments ; others function as electronic logbooks, expediting the storage, evaluation, and inter pretation of diabetes management data. Education programs are available to teach health profes sionals and people with diabetes how to perform a variety of tasks, including insulin administration and blood and urine glucose testing. Simulations of clinical situations enable nurses to sharpen their diabetes management skills; other programs use gamelike formats to educate young people and adults who have diabetes about the disease. This brief survey describes some computer software programs identified by the National Diabetes Information Clearinghouse (NDIC) of the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health. Information regarding computer compatibility, price, and source is provided for the programs discussed in the paper.

Influence of selective endoperoxide/thromboxane A2 receptor antagonism with sulotroban on lysis time and reocclusion rate after tissue plasminogen activator-induced coronary thrombolysis in the dog

The purpose of this investigation was to examine the potential beneficial effect of the selective endoperoxide/thromboxane A2 (TxA2) receptor antagonist, sulotroban (BM 13.177), on tissue type plasminogen activator (tPA)-induced coronary thrombolysis in the dog. A stenosis that eliminated reactive hyperemic capacity was placed on the circumflex coronary artery and an occlusive thrombus was produced by electrical injury to the intimal surface of the artery. Upon occlusion, sodium heparin was administered (300 U/kg i.v.) followed by 100 U/kg i.v. every hour thereafter. All dogs received i.v. tPA 60 min after the formation of the occlusive thrombus at a dose of 10 micrograms/kg/min for up to 90 min, if necessary, to elicit reperfusion. Thrombolysis was demonstrated in all dogs by restoration of coronary blood flow. Dogs were randomized to one of three groups. Group I consisted of 24 animals that received vehicle infusion along with tPA. Group II consisted of 10 animals that received sulotroban at a bolus dose of 1 mg/kg i.v. followed by 1 mg/kg/hr i.v. administered simultaneously with tPA. Group III consisted of 11 animals that received sulotroban at a bolus of 10 mg/kg i.v. followed by 10 mg/kg/hr i.v. administered simultaneously with tPA. Infusions of either vehicle or sulotroban were continued for 2 hr, post-thrombolysis. tPA was infused for at least 30 min, after which infusion of tPA was terminated upon achieving a reperfusion level of coronary blood flow equivalent to 50% or greater than control blood flow. All animals occluded spontaneously to electrolytic stimulation between 32 and 62 min. tPA-induced thrombolysis occurred in Group I vehicle-infused animals at 32 +/- 5 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved cat gene cassette for promoter analysis and genetic constructions

A plasmid, pJS133, was constructed which contains a promoterless cat gene encoding chloramphenicol (Cm) acetyltransferase (CAT) conferring Cm resistance. This improved cat cassette, derived from the cat gene in plasmid pKK232-8 [Brosius, Gene 27 (1984) 151-160], offers several advantages over currently available cat cassettes. Expression of cat from this cassette reflects only transcriptional activity because of translational stops in all three reading frames, and possesses facile insertion/excision properties employing the flanking polylinker restriction sites. In plasmid pJS133, this cassette can be obtained by a single digestion with SmaI, HindIII, SalI, BamHI or PstI restriction enzymes. Additionally, 28 different cat cassettes with unique flanking restriction sites can be created by the appropriate double digestions.

Immunochemical quantitation, size distribution, and cross-reactivity of lepidoptera (moth) aeroallergens in southeastern Minnesota

With an immunochemical method, we analyzed outdoor air samples during a 3-year period for concentrations of the predominant local species of moth, Pseudaletia unipuncta (Haworth). Airborne particulates were collected on fiberglass filter sheets with an Accu-Vol sampler located 1.5 m above ground on the southeastern Minnesota prairie. Filter eluates analyzed by RIA inhibition contained concentrations of moth protein peaking in June and August to September of each year, with levels comparable to reported immunochemically measured levels of pollen and mold allergens. These peaks also corresponded with total numbers of moths captured in light traps. Moth-allergen activity was distributed in particle sizes ranging from 0.8 to greater than 4.1 micron when sized samples were obtained by use of an Andersen cascade impaction head. By RIA inhibition, there was cross-reactivity between P. unipuncta and insects of different genera, families, and orders, but not with pollens or molds. Forty-five percent of 257 patients with immediate positive skin tests to common aeroallergens had positive skin tests to one or more commercially available whole body insect extracts. Of 120 patients with allergic rhinitis believed to be primarily caused by ragweed sensitivity, 5% also had elevated specific IgE to moths. We conclude that airborne concentrations of Lepidoptera can be measured immunochemically and that moths may be a seasonal allergen in the United States.

Identification of a site of ATP requirement for signal processing in bacterial chemotaxis

In Escherichia coli and Salmonella typhimurium, ATP is required for chemotaxis and for a normal probability of clockwise rotation of the flagellar motors, in addition to the requirement for S-adenosylmethionine (J. Shioi, R. J. Galloway, M. Niwano, R. E. Chinnock, and B. L. Taylor, J. Biol. Chem. 257:7969-7975, 1982). The site of the ATP requirement was investigated. The times required for S. typhimurium ST23 (hisF) to adapt to a step increase in serine, phenol, or benzoate were similar in cells depleted of ATP and in cells with normal levels of ATP. This established that ATP was not required for the chemotactic signal to cross the inner membrane or for adaptation to the transmembrane signal to occur. Depletion of ATP did not affect the probability of clockwise rotation in E. coli cheYZ scy strains that were defective in the cheY and cheZ genes and had a partially compensating mutation in the motor switch. Strain HCB326 (cheAWRBYZ tar tap tsr trg::Tn10), which was deficient in all chemotaxis components except the switch and motor, was transformed with the pCK63 plasmid (ptac-cheY+). Induction of cheY in the transformant increased the frequency of clockwise rotation, but except at the highest levels of CheY overproduction, clockwise rotation was abolished by depleting ATP. It is proposed that the CheY protein is normally in an inactive form and that ATP is required for formation of an active CheY* protein that binds to the switch on the flagellar motors and initiates clockwise rotation. Depletion of ATP partially inhibits feedback regulation of the cheB product, protein methylesterase, but this may reflect a second site of ATP action in chemotaxis.

Altered biochemical and functional responses in aorta from hypertensive rats

Factors that lead to supersensitivity of vascular smooth muscle to norepinephrine during aldosterone-salt-induced hypertension in rats appear to reside beyond ligand-alpha-adrenergic receptor binding, which we have shown previously to be normal. The objective of this study was to determine whether significant shifts occur in the coupling between receptors and the production of putative second messengers. Measures of [3H]myo-inositol phosphates in aorta (endothelium removed) exhibited a concentration-dependent increase to norepinephrine, with the 50% response shifted significantly to the left in the hypertensive group (7.0 +/- 0.9 X 10(-7) M in 8 control rats vs 1.1 +/- 0.2 X 10(-7) M in 8 hypertensive rats; p less than 0.001). The production of [32P]phosphatidic acid was also shifted (6.5 +/- 2.5 X 10(-7) M in 16 control vs 1.9 +/- 0.8 X 10(-7) M in 12 hypertensive rats; p less than 0.05). The functional responses of 42K efflux and contraction to norepinephrine were also significantly shifted threefold to 15-fold in the hypertensive group (p less than 0.001), but the 50% response typically occurred at a 10 to 100 times lower concentration than that for the production of myo-inositol phosphates and phosphatidic acid. The amplification between receptor occupancy and functional responses apparently occurs beyond the production of phosphoinositide metabolites. The fivefold shift in the 50% response of biochemical end points for the hypertensive group accounted for most of the shift (sixfold) in the functional end points.(ABSTRACT TRUNCATED AT 250 WORDS)

Self-assembly of apoferritin from horse spleen after reversible chemical modification with 2,3-dimethylmaleic anhydride

Apoferritin from horse spleen is composed of 24 subunits that undergo partial dissociation after chemical modification with 2,3-dimethylmaleic anhydride (DMMA), yielding dimeric, trimeric, and tetrameric intermediates, stable at pH 8.5 and 0 degrees C. Deacylation at neutral pH and elevated temperature provides a means to initiate reassembly by appropriate shifts of the solvent conditions. In order to monitor the pathway of self-assembly, starting from different intermediates of dissociation, dimers, trimers, and tetramers were isolated and investigated with respect to their capacity to accomplish reassociation. Intrinsic protein fluorescence, gel permeation chromatography, and analytical ultracentrifugation were applied to characterize the intermediate and final stages of association. The assembly of both the dimer and trimer yields greater than 85% of the native tetracosamer; the overall rate, starting from the dimer, exceeds the one starting from the trimer. Under comparable conditions, the tetramer exhibits only partial reassociation via the dimer and monomer; the corresponding dissociation reaction determines the observed slower rate. Significant assembly intermediates are "structured monomers", dimers, trimers, and dodecamers. Polymerization of the dimer via the tetramer, octamer, etc., does not occur on the pathway of assembly. The results confirm the assembly scheme proposed previously on the basis of cross-linking and spectroscopic experiments [Gerl, M., & Jaenicke, R. (1987) Eur. Biophys. J. 15, 103-109]. Comparison of structural models involving the different subunit interactions responsible for the sequential association supports the monomer----dimer----trimer----hexamer----dodecamer----tetracosamer mechanism of apoferritin self-assembly.