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Biomedical subjects

C Hatfield

Publications and source records attributed to C Hatfield.

9 recordsLinked to original sources
PubMed2004

Efficacy and tolerability of lumiracoxib in the treatment of primary dysmenorrhoea.

Two randomised, multicentre, double-blind, placebo- and active-controlled, 3-way crossover studies were performed to evaluate the efficacy and tolerability of the novel COX-2 selective inhibitor lumiracoxib in the treatment of primary dysmenorrhoea. Subjects with moderate-to-severe dysmenorrhoea received lumiracoxib 400 mg once daily (od), rofecoxib 50 mg od and placebo (Study 1; n = 84) or lumiracoxib 400 mg od, naproxen 500 mg twice daily and placebo (Study 2; n = 99). For the primary variable, summed pain intensity difference from 0 to 8 h on day 1 (SPID-8), all active treatments were superior to placebo in each study (p < 0.001); lumiracoxib was comparable to rofecoxib and naproxen. For PID (categorical scale), all active treatments were significantly better than placebo from 2 to 12 h; lumiracoxib was generally comparable to rofecoxib and naproxen. All treatments were well tolerated. Lumiracoxib 400 mg is effective and well tolerated in the treatment of primary dysmenorrhoea, with efficacy comparable to rofecoxib and naproxen.

Adolescent↗
PubMed1998

Antigenic variation of varicella zoster virus Fc receptor gE: loss of a major B cell epitope in the ectodomain.

Varicella zoster virus (VZV) is considered to possess a genetically stable genome; only one serotype is recognized around the world. The 125-kbp genome contains approximately 70 open reading frames. One that has received particular attention is open reading frame 68, which codes for glycoprotein gE, the predominant 623-residue viral envelope product that harbors both B and T cell epitopes. This report describes the initial characterization of a community-acquired VZV isolate that was a distinguishable second serotype (i.e., it had lost a major B cell epitope defined on the gE ectodomain by a murine monoclonal antibody called mAb 3B3). The mAb 3B3 epitope was found not only on the prototype sequenced Dumas strain from Holland and all previously tested North American isolates but also on the varicella vaccine Oka strain originally attenuated in Japan. Sequencing of the mutated gE ectodomain demonstrated that codon 150 exhibited a single base change that led to an amino acid change (aspartic acid to asparagine). Observation of the monolayers infected with the mutant VZV strain also led to the surprising discovery that the topography of egress was altered. Wild-type VZV emerges along distinctive viral highways, whereas the mutant strain virions were nearly uniformly distributed over the cell surface in a pattern more closely resembling egress of herpes simplex virus 1. The mutant VZV strain was designated VZV-MSP because it was isolated in Minnesota.

Amino Acid Sequence↗
PubMed1997

Epitope mapping and tagging by recombination PCR mutagenesis.

We describe a rapid PCR method that directly inserts an epitope tag into an open reading frame (ORF) to facilitate protein detection. This project was performed within a varicella-zoster virus (VZV) system. In earlier work, we produced a monoclonal antibody (MAb 3B3) to one VZV ORF called gE. MAb 3B3 bound to its epitope under extreme denaturing conditions. To further characterize the epitope, we devised a technique that identified the epitope by its insertion into another protein of interest. The 3B3 epitope was mapped to 11 residues (residues 151-161; QRQYGDVFKGD) in the gE ectodomain by using the technique of recombination PCR. At the same time, the 3B3 epitope was inserted in-frame into another VZV protein for which no MAb was available. The end result, VZV gL3B3.11, was a unique construct possessing a 33-bp insertion that expresses gL-3B3 protein recognized by the MAb 3B3. The 3B3 epitope was verified to be both highly functional and stable. An important advantage of this recombination PCR method of epitope mapping and tagging is that the epitope sequence can be inserted anywhere along the nucleotide sequence of an ORF, regardless of existing restriction sites.

Amino Acid Sequence↗
PubMed1997

Principles of drug administration in renal insufficiency.

Normal renal function is important for the excretion and metabolism of many drugs. Renal diseases which affect glomerular blood flow and filtration, tubular secretion, reabsorption and renal parenchymal mass alter drug clearances and lead to the need for alterations in dosage regimens to optimise therapeutic outcome and minimise the risk of toxicity. Renal disease is increasing and the cost of care has risen progressively over the past decade. Part of these costs is related to inappropriate drug therapy and excessive drug use. Although there are a variety of methods for evaluating the various aspects of renal function, the most practical and commonly used clinical measure of renal function is estimated creatinine clearance (CLCR) as a marker for glomerular filtration. This is useful since alterations in drug clearance are proportional to alterations in CLCR, and this relationship is used as the basis for changing doses and dosage intervals for drugs which are largely renally excreted. Two populations, neonates and the elderly, are at risk of inappropriate drug dosage due to physiological changes in renal function. Estimated CLCR may not be the best method of evaluating renal function in these patients, and dosage regimens should be carefully considered. Renal insufficiency and concurrent drug therapy used in these populations can either increase or decrease drug absorption, depending on the particular agent. Drug distribution may be altered in renal insufficiency due to pH-dependent protein binding and reduced protein (primarily albumin) levels. Interestingly, renal disease may affect hepatic as well as renal drug metabolism; the exact mechanisms for these changes are not well understood. The most important quantitative pharmacokinetic change is excretion. Glomerular filtration and tubular process may both be affected but not to the same extent, and the type of renal disease may differentially affect filtration and excretion. Drug removal by dialysis is dependent on a number of factors, including the characteristics of a particular drug and the type of dialysis and equipment used. Therapeutic outcomes may be evaluated using end-points such as plasma concentrations, patient outcomes such as reduction in fever or negative cultures, and system-wide changes such as drug-use or laboratory-use patterns.

Humans↗
PubMed1995

Cell surface expression and fusion by the varicella-zoster virus gH:gL glycoprotein complex: analysis by laser scanning confocal microscopy.

Varicella-zoster virus (VZV) open reading frames 37 and 60 encode the glycoproteins gH (gpIII) and gL (gpVI), respectively. The property of gH:gL complex formation is highly conserved among the herpesviruses, even though the VZV gL component diverges greatly from other herpesvirus gL homologs. VZV gL by itself was processed to a mature product within the Golgi. To evaluate the structure:function relationships for VZV gH:gL complex formation, the VZV gL product was modified by site-directed mutagenesis of three cysteine residues. When the transfection products were examined by laser scanning confocal microscopy, expression of the wild-type gH:gL complex was clearly visualized by a uniform distribution of gH molecules across the cell surface. In contrast, transfection with wild-type gH:mutant gL led to a marked change in the trafficking pattern; gH was not processed in the Golgi and not detected at the cell surface. Likewise, replacement of the gL cysteine residues interfered with the fusogenic properties of the gH:gL complex. Whereas coexpression of wild-type VZV gH:gL caused extensive cell-to-cell fusion with polykaryocytosis, no cell fusion occurred following transfection with gH:mutant gL. Whether another VZV glycoprotein could substitute for VZV gL was investigated within the same transfection system, with the discovery that either VZV gE (gpI) or VZV gI (gpIV) facilitated the cell surface expression of VZV gH. The gH:gE or gH:gI interaction led to a capping or patching phenomenon never seen on the surface of a cell expressing gH:gL complexes; furthermore, cell-to-cell fusion was not observed. The fact that VZV gL, unlike other herpesviral glycoproteins, lacked a traditional signal sequence was investigated further by computer-assisted BlockSearch sequence analysis. The BlockSearch program assigned VZV gL to a family of proteins which lack a typical endoplasmic reticulum signal sequence but possess instead an endoplasmic reticulum targeting sequence. Since the latter sequence is common to many chaperone proteins, VZV gL most likely behaves in a similar manner.

Amino Acid Sequence↗
PubMed1989

Occipitoatlantoaxial malformation with duplication of the atlas and axis in a half Arabian foal.

An unusual occipitoatlantoaxial malformation is described in a 2-week-old male part Arabian foal that was unable to stand at birth and showed signs of spastic tetraparesis due to a cervical spinal cord compression. There were 2 atlases present. One was fused to the occipital bones. The other articulated with the first atlas and an axis which had a long dens that projected into the vertebral canal. Examination of the ossification centers of the axis indicated partial duplication of that bone.

Abnormalities, Multiple↗
PubMed1975

The 21 point vision analysis without a phoropter.

This paper offers a sequence of valid tests, objective in nature, to measure the vision performance and provide an appropriate prescription for an individual who is unable to undergo the demands of a 21 point analytical refraction, through a phoropter, due to age, intelligence or communication difficulty.

Humans↗
PubMedDate not supplied

Pentamidine sensitivity and resistance in Saccharomyces cerevisiae as a model for pentamidine effects on Pneumocystis carinii.

Pentamidine isethionate inhibits growth of Saccharomyces cerevisiae. Inhibition requires lower drug concentrations under respiratory than fermentative growth conditions. Pentamidine-resistant strains bear heritable resistance mutations. Tested mutations are dominant to wild type sensitivity. These mutations may identify cellular targets of pentamidine and potential mechanisms of fungal pentamidine resistance.

Cations, Divalent↗