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Biomedical subjects

A M Phillips

Publications and source records attributed to A M Phillips.

At least 37 records · Page 2Linked to original sources
PubMed1996

Current techniques in total knee replacement: results of a national survey.

A postal questionnaire was sent to all Fellows of the British Orthopaedic Association to obtain a census of total knee replacement (TKR) preferences in the United Kingdom; 1162 questionnaires were sent and 721 replies received. There were 92 Fellows who had retired or filled in the forms incorrectly, and 32 no longer perform TKR. Thus, 597 responded correctly, giving a 62% response rate. This gives an extrapolated total of 34,677 TKRs being implanted per year in the UK, with an average of 34.3 being performed by each surgeon per year. Only 9% perform more than 90 per year. There were 41 different prostheses in current use among the respondents to our questionnaire, of which five prostheses constituted 61% of the total. Cemented prostheses were used by 95.2%. Resurfacing of the patella was always carried out by 32%, while 19% never resurface it; the most common reason for doing so being patellofemoral arthropathy at operation. Intramedullary alignment was used for the femoral component in 86%, 76% preferred extramedullary alignment for the tibial component. Regarding cementing technique, 43% use pulsatile lavage, 9% used a cement gun, 88% dry the bone and 56% seal the hole made by the femoral alignment device in the femur before cementing. All components were cemented simultaneously by 65% and one at a time by 31%. Metal-backed tibial prostheses are now used by 98% of surgeons, modular tibial components being preferred by 80%. Metal-backed patellar components were used by 13%. An onlay type of patella was preferred by 51%. This survey highlights the great diversity of surgical practice in the UK, which may reflect uncertainty regarding best practice in total knee replacement.

Attitude of Health Personnel↗
PubMed1994

Evaluation of three methods for the rapid identification of Staphylococcus aureus in blood cultures.

A total of 445 blood cultures containing Gram-positive cocci in clusters were tested for the presence of Staphylococcus aureus with the Accuprobe, heat-stable thermonuclease, and latex agglutination using Staphaurex. The results show that the Accuprobe, thermonuclease, and Staphaurex correctly identified 95, 96, and 62 of the 100 specimens containing S. aureus. The corresponding specificity for the methods was 99.1%, 100%, and 98.5%, respectively.

Bacteremia↗
PubMed1993

Laser-induced protein-DNA cross-links via psoralen furanside monoadducts.

We have developed a technique for cross-linking DNA binding proteins to DNA using psoralen furanside monoadducts as photoaffinity probes and a continuous-wave argon ion laser (366 nm) as a light source. Several DNA binding proteins (T7 RNA polymerase, UvrB, single-stranded DNA binding protein of Escherichia coli, T4 gp32, and RecA of E. coli) are shown to cross-link to single-stranded psoralen monoadducted DNA oligos differing in length and sequence. Increasing fluences of laser light on a fixed ratio of DNA/protein resulted in an increase in the yield of cross-links. Titration experiments were carried out to measure the apparent cross-linking constant (KappXL) for T7 RNA polymerase or UvrB to a monoadducted 24 mer DNA. The estimated values for the apparent cross-linking constant were in the range of (2-3) x 10(-7) M for both T7 RNA polymerase and UvrB. The efficiency of cross-linking was investigated as a function of the length of adducted DNA and also as a fraction of the total noncovalent binding of proteins of psoralenated DNAs. The results showed that in the cases of T7 RNA polymerase and UvrB cross-linking was more efficient with short oligos (8 and 19 mers) as compared to longer oligos (50 mer). A tryptic peptide of T7 RNA polymerase that was conjugated to a psoralen furanside monoadducted 12 mer DNA was isolated by high-performance liquid chromatography. Mass spectrometry and amino acid composition of this peptide revealed that it originated from a region between residues 558 and 608 of the primary structure of T7 RNA polymerase. Two other peptides cross-linked to oligos were also purified. Repeated attempts to perform Edman sequencing of the peptide-DNA conjugates failed. Overall evidence indicates that photo-cross-linking of furanside monoadducts occurred at multiple sites on the proteins. We have shown that T7 RNA polymerase molecules in a ternary complex arrested at the furanside monoadduct can be cross-linked to the DNA templates with laser light. Evidence suggests that the arrested polymerase molecules existed in multiple conformations on the DNA template. This method of transcriptional cross-linking offers a new method for preparing highly stable elongation complexes for further studies.

Bacteriophage T7↗
PubMed1993

A neural gene from Drosophila melanogaster with homology to vertebrate and invertebrate glutamate decarboxylases.

Cross-species hybridization has been used to isolate a second Drosophila gene, with homology to a feline glutamate decarboxylase (Gad) cDNA. The gene differs in sequence, chromosomal location, and spatial expression from the previously reported Drosophila Gad gene, but both encode proteins of 58 kDa. The derived amino acid sequence reveals a typical pyridoxal phosphate binding site and sequence homology consistent with a glutamate decarboxylase function. The protein includes an amino-terminal polyasparagine sequence, and a beta-pleated sheet region, with regularly spaced glutamine and arginine residues, not found in other decarboxylases. Expression in the adult is limited to the neuropil of the first optic ganglion and to regions of the thoracic musculature that may correspond to the location of motor neuron axons. This is consistent with a glial localization for the transcript. There is no overlap with the reported expression of Drosophila Gad. Although the molecular evidence suggests that this gene encodes a pyridoxal phosphate-dependent decarboxylase, glutamate decarboxylase activity associated with this gene could not be demonstrated, and the in vivo substrate is unknown. It is possible that the protein encoded by this gene is novel, not only in sequence and spatial expression, but also in substrate specificity.

Amino Acid Sequence↗
PubMed1992

Active site of (A)BC excinuclease. II. Binding, bending, and catalysis mutants of UvrB reveal a direct role in 3' and an indirect role in 5' incision.

UvrB plays a central role in (A)BC excinuclease. To study its role in the incision reactions, conserved His and Asp residues in this subunit were mutagenized. All His and the majority of Asp mutants behaved like wild-type protein in vivo and in vitro. However, three mutants, D337A, D478A, and D510A, either completely or partially abolished UvrB activity. All three mutant proteins associate with UvrA normally but D337A and D510A were unable to bind to DNA specifically. The UvrB-D478A mutant bound to DNA specifically but failed to denature and kink the DNA. However, UvrB-D478A was efficiently loaded onto DNA preincised at the 3' site and promoted near-normal incision by UvrC at the 5' site. We propose that D478 is involved in bending DNA and catalysis of the 3' incision and that the 3' incision precedes the 5' incision. UvrB which is missing the carboxyl-terminal 43 amino acids binds to, and kinks DNA but is unable to make the 3' incision suggesting that it is missing a residue involved in catalysis. This residue was identified to be E639 by site-specific mutagenesis.

Adenosine Triphosphatases↗
PubMed1992

Identification of a Drosophila gene encoding a calmodulin-binding protein with homology to the trp phototransduction gene.

We have isolated a number of Drosophila cDNAs on the basis of their encoding calmodulin-binding proteins. A full-length cDNA clone corresponding to one of these genes has been cloned and sequenced. Conservation of amino acid sequence and tissue-specific expression are observed between this gene and the transient receptor potential (trp) gene. We propose the name transient receptor potential-like (trpl) to describe this newly isolated gene. The trpl protein contains two possible calmodulin-binding sites, six transmembrane regions, and a sequence homologous to an ankyrin-like repeat. Structurally, the trpl and trp proteins resemble cation channel proteins, particularly the brain isoform of the voltage-sensitive Ca2+ channel. The identification of a protein similar to the trp gene product, yet also able to bind Ca2+/calmodulin, allows for a reinterpretation of the phenotype of the trp mutations and suggests that both genes may encode light-sensitive ion channels.

Amino Acid Sequence↗
PubMed1989

Exposure to ceramic man-made mineral fibres.

Ceramic fibres (also known as refractory fibres) are regarded here as man-made mineral fibres (MMMF) capable of withstanding temperatures of 1000-1600 degrees C without appreciable distortion or softening. Ceramic fibres are manufactured largely from the aluminosilicate group of minerals but some contain only alumina, zirconia or silica. Simultaneous personal gravimetric and optical fibre count samples were taken throughout the industry. It has not been possible to correlate gravimetric results with fibre counts in any meaningful way. The general conclusions are as follows: (a) gravimetrically, exposures ranged from less than 1 mg/m3 for light tasks to over 10 mg/m3 for some insulation workers. Exposures above 10 mg/m3 were not necessarily associated with correspondingly high fibre counts; (b) fibre counts rarely exceeded 1 f/ml, and it appears that ceramic fibre materials, in company with other MMMF, do not readily produce high airborne fibre counts; (c) control of dust from mineral wools to 5 mg/m3 achieves control to below 1 f/ml. This relationship does not hold for superfine MMMF and does not always hold for ceramic fibres.

Air Pollutants↗
PubMed1988

Detection of haematoporphyrin derivative and haematoporphyrin excited states in cell environments.

The photosensitiser currently used in the photodynamic therapy of cancer is haematoporphyrin derivative. Pulsed laser studies of this material and also of the "parent" molecule haematoporphyrin in polyoma-transformed fibroblast cells have now been studied. We report, for the first time, the observation of the triplet absorption of these sensitisers in cells. The corresponding triplet-triplet spectra are red shifted compared to aqueous buffer, lambda(max) 420 nm shifts to 460 nm. We also report our failure to observe singlet oxygen from the cells even though the triplet state can be seen to interact with the oxygen and even though singlet oxygen can be readily detected with the same sensitisers bound to serum albumin.

Cell Line↗
PubMed1988

Transcutaneous electrical nerve stimulation in the management of acute postoperative pain.

Twenty patients undergoing decompressive lumbar laminectomy were randomly allocated, in a double-blind manner, to receive active or inactive transcutaneous electrical nerve stimulation (TENS) as part of the management of their postoperative pain. All patients received the same non-narcotic general anaesthetic. The efficacy of the TENS was assessed by using a patient-controlled analgesia system (PRODAC) which delivered morphine i.v. This system recorded the number of demands for analgesia and the total dose administered in the first 24 h. In addition, plasma morphine concentrations were measured hourly for the first 6 h and again at 24 h. There was no statistical difference between the two groups in the number of patient demands for analgesia, morphine dose or plasma morphine concentration. TENS offered no advantage over a placebo in the management of acute postoperative pain in these patients.

Acute Disease↗
PubMed1988

Cocaine and homicide in Memphis and Shelby county: an epidemic of violence.

In Memphis and the surrounding county, there were a record number of homicides (179) in 1986. During the same year, there was a marked increase in medical examiner cases where tests were positive for cocaine or its metabolites. Review of medical examiner and toxicology records from 1980 to 1986 found 87 cocaine related deaths; 46 of these were homicides. In 1986 alone, there were 53 cocaine related deaths, all manners, and 31 cocaine related homicides. In this year, 17.3% of the homicides were positive for cocaine or metabolite. The cocaine related homicides were similar to other homicides in terms of age, race, sex, blood ethanol concentration, and cause of death being due most often to firearms. In homicide cases in which an abuse drug was detected, cocaine accounted for the entire increase in 1986. Police records indicated that cocaine directly contributed to the homicide in 39% of the cases in which the drug was found. In other cases, we speculate that cocaine altered behavior may have contributed to the victim's being murdered either during the drug "high" or during the posteuphoric depression or withdrawal phase.

Adult↗
PubMed1987

Haematoporphyrin photosensitisation treatment of experimental choroidal melanoma.

Greene amelanotic melanoma transplanted to pigmented rabbit choroid provided the experimental model for studying photosensitisation treatment of choroidal melanoma. Administration of haematoporphyrin derivative (HPD) and subsequent photoradiation with green laser light destroyed much of the melanoma with minimal side effects to normal uvea. The results of treatment were documented by fundus photography and fluorescein angiography. By 24 hours, the irradiated melanoma and surrounding retina appeared whitened and necrotic, with complete non-perfusion of the area. Over the course of one week, the clinical appearance did not alter. Histopathology at 24 hours and 8 days confirmed massive central tumour necrosis, but in all cases this was subtotal. Viable cells were evident at the periphery and also along the base of the tumour. Experimental evaluation of treatment parameters is required before this technique can be recommended for human choroidal melanoma.

Animals↗
PubMed1983

Nonlinear gel electrophoresis: an analogy with ideal fluid flow.

The behavior of electrolytes undergoing electrophoresis in various shaped gels was investigated using bromphenol blue as a model electrolyte. The results suggest that during gel electrophoresis, small electrolytes behave in a manner analogous to the flow of ideal, irrotational fluids.

Bromphenol Blue↗
PubMed1983

Clinical pharmacology of netilmicin in the newborn.

The plasma peak, trough, and peak-trough concentrations of netilmicin given to preterm and term infants were measured after different regimens to determine which dosage would provide satisfactory peak and trough concentrations. In infants aged less than 7 days, dosage regimens of 3.0 or 2.5 mg/kg every 12 hours gave satisfactory peak levels (range 5.2-12.0 micrograms/ml) but troughs were above the desirable maximum level of 3 micrograms/ml in more than half the preterm infants. Subsequently a dosage regimen of 3.0 mg/kg immediately followed by 2.0 mg/kg every 12 hours resulted in trough levels that exceeded 3 micrograms/ml in only 2 of 25 preterm determinations and never in term infants, yet gave satisfactory peak levels (range 4.5-7.4 micrograms/ml). In preterm infants aged 4 to 7 weeks a dosage of 3 mg/kg every 8 hours gave satisfactory peak and trough levels.

Body Weight↗