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Biomedical subjects

P S Hicks

Publications and source records attributed to P S Hicks.

9 recordsLinked to original sources
PubMed2002

Comparative in vitro activity of ertapenem against bacterial pathogens isolated from patients with lower respiratory tract infections.

This study compared the in vitro activity of ertapenem, ceftriaxone, cefepime, ciprofloxacin and amoxicillin-clavulanate against 381 aerobic and facultative bacterial pathogens isolated from 320 patients with acute bacterial exacerbation of chronic bronchitis or community-acquired pneumonia. Streptococcus pneumoniae and Haemophilus influenzae accounted for 54.6% of the isolates. The ertapenem MIC was < or =2 mg/L for 98.4% of isolates and > or =8 mg/L for 1.0% (all methicillin-resistant Staphylococcus aureus). Ertapenem had the most potent activity against Enterobacteriaceae, Moraxella catarrhalis, and methicillin-susceptible S. aureus, and its activity against H. influenzae and H. parainfluenzae, all strains of which were susceptible, was not altered by beta-lactamase production. Only one S. pneumoniae strain, a penicillin-resistant isolate, was resistant to ertapenem. Ertapenem was highly active in vitro against pyogenic bacteria recovered from patients with community-acquired lower respiratory tract infections.

Anti-Bacterial Agents↗
PubMed1995

Quantitative measurement of muscle strength in the mouse.

We have designed a special dynamometer for measuring mouse forelimb muscle strength and endurance. The device exploits a mouse's tendency to grasp a horizontal metal bar while suspended by its tail. A threshold value for the magnitude and duration of force that the mouse can exert is obtained by first allowing the animal to grasp the bar and then applying a steadily increasing downward force to the opposite end of a cable to which the mouse attaches. The bar is attached to a force transducer and pen recorder to produce a permanent record of the force produced by the mouse. Test results show that this dynamometer provides quantitative measurements of muscle strength and endurance in the mouse. Comparisons between experimental groups of normal and wobbler mice, a model for lower motor neuron disease, show that both the force exerted by the animals (muscle strength), and the duration of the pull (endurance), can be quantified and statistically analyzed. This technique can be used as an assay for quantitating the effects of in vivo drug treatments on murine neuromuscular disorders.

Animals↗
PubMed1994

Decreased autoantibody levels and enhanced survival of (NZB x NZW) F1 mice treated with C-reactive protein.

C-Reactive protein (CRP) is the prototypic acute-phase serum protein in man. On the basis of its binding specificities and activities, it has been proposed that CRP facilities the removal of nuclear material released from damaged cells. To determine whether such a process could alter the development of autoimmunity to nuclear antigens, the effect of CRP on autoimmune disease in the (NZB x NZW) F1 mouse model of systemic lupus erythematosus was tested. Mice were injected with chromatin bound to latex beads in the presence or absence of bound CRP. CRP treatment significantly prolonged survival of mice injected with chromatin-coated beads. CRP also produced a transient decrease in IgG antibody levels to histones, DNA, and DNP, suggesting a general suppressive effect on ongoing antibody responses. To determine whether CRP would affect chromatin clearance, the effect of CRP on nucleosome core particle clearance was tested in BALB/c mice. CRP pretreatment did not alter the rate of clearance or organ localization of nucleosome core particles. These findings indicate that CRP can modify the course of autoimmune disease possibly by preventing the exposure of nuclear antigens to the immune system.

Animals↗
PubMed1992

Serum amyloid P component binds to histones and activates the classical complement pathway.

Two members of the pentraxin family of proteins, C-reactive protein (CRP) and serum amyloid P component (SAP), bind to chromatin and may be involved in the solubilization and clearance of nuclear material. Previous studies demonstrated that CRP binding to chromatin is mediated by histones. SAP differs from CRP in being able to bind to DNA, but SAP binding to histones has not been reported. CRP is an activator of the classical C pathway, and C-dependent cleavage of chromatin in the presence of CRP and serum has been shown. Oligomers of SAP have recently been found to bind to C1q and consume total C and C4, indicating that SAP can activate C as well. The present study examined CRP and SAP binding to histones H1 and H2A and C activation after binding. SAP binding to histones H1 and H2A was observed as well as SAP binding to chromatin. In contrast to CRP, SAP binding to chromatin did not require H1. SAP partially inhibited CRP binding to chromatin and to H1. However, neither pentraxin inhibited binding of the other to H2A. Binding of either CRP or SAP to H2A activated C in SAP-depleted serum leading to the deposition of C4 and C3. C activation required C1q and produced C4d indicating that it occurred through the classical pathway. These findings demonstrate that CRP and SAP share histone as well as chromatin binding, and that both pentraxins can activate the classical C pathway after ligand binding.

Animals↗
PubMed1988

Interactions of Escherichia coli transcription termination factor rho with RNA. II. Electron microscopy and nuclease protection experiments.

Structural aspects of the interaction between Escherichia coli transcription termination factor rho and RNA have been investigated, using nuclease protection assays and electron microscopy. A synthetic RNA, poly(rC), has been used as a substrate for these studies, since it binds tightly to rho and acts as a strong activator of the ATPase activity of rho. Digestion of oligo(rC)-rho complexes with ribonuclease A yields oligo(rC) fragments with a maximum length of 70 to 80 nucleotide residues. Electron micrographs demonstrate that rho binds to poly(rC) as a toroid-shaped oligomer with an outside diameter of approximately 120 A. Taken together with data from the accompanying paper, which shows that the RNA binding site size per rho monomer is 13(+/- 1) nucleotide residues, we infer that rho binds RNA as a hexamer with an oligomeric site size of 72 to 84 residues. Further analysis of the electron micrographs has revealed that the polynucleotide chain is wrapped around, or condensed within, the protein oligomer. rho hexamers bind to poly(rC) with moderate co-operativity (omega = 380 +/- 60), displaying no significant preference for binding to chain ends versus internal sites on the polynucleotide chain. These findings and those of the companion paper are discussed in terms of various models for the structure of the rho-RNA complex in transcription termination.

Allosteric Site↗