Biomedical subjects

P G West

Publications and source records attributed to P G West.

12 recordsLinked to original sources

PubMed1996

Histomorphometric and angiographic analysis of the humerus in pigeons.

OBJECTIVE: To identify the vascular supply and resorption/formation activity of the humerus of pigeons. DESIGN: Pigeons were injected with the fluorochrome label oxytetracycline and, 5 days later, with the label calcein. 5 days after administration of the second fluorochrome, a wing from each bird was infused with a microparticle barium solution immediately after euthanasia and the chosen humerus was prepared for angiography while the opposite was prepared for histomorphometry. ANIMALS: 17 nine-month-old pigeons, consisting of 9 male and 8 female birds. PROCEDURE: At euthanasia, 1 wing was chosen for infusion and the barium solution was injected through a catheter in the brachiocephalic artery. Both humeruses were harvested. The infused humerus was decalcified, radiographed, and sectioned for H&E staining. The opposite humerus was sectioned and measured by use of a morphometric analyzing system to determine cross-sectional area, endosteal and periosteal perimeters, and percentage of perimeter containing a single and/or double label. RESULTS: All pigeons had an intramedullary arterial supply. The bones had a quiescent appearance histologically, consisting principally of lamellar bone with few osteospecialized cells, resorption surfaces, or osteons. Less than 10% of either the periosteal or endosteal surface acquired a fluorochrome label. CONCLUSIONS: The intramedullary vascular supply of the humerus is similar in structure to the vascular supply to mammalian bones. The humerus is, however, a quiescent bone in the sexually mature pigeon, with little remodeling activity present. CLINICAL RELEVANCE: The intramedullary blood supply may have an important role in the healing of humeral fractures in avian species.

Analysis of Variance↗

PubMed1996

Histomorphometric and angiographic analysis of bone healing in the humerus of pigeons.

OBJECTIVE: To evaluate the vascular supply and quantitatively compare the periosteal and endosteal callus formed during fracture healing. DESIGN: 36 pigeons were allotted to 2 groups. In each bird, 1 humerus was surgically osteotomized. The wing with the fractured humerus in birds of the first group was infused with a microparticle barium solution, and the humerus was harvested for angiography. Pigeons of the second group were injected with the labels oxytetracycline and calcein. The fractured humerus in each of these birds was harvested for histomorphometry. ANIMALS: 36 nine-month-old pigeons, consisting of 19 male and 17 female birds. PROCEDURE: 1 humerus from each of the 36 pigeons was osteotomized in the center of the bone by use of an obstetrical wire. All fractured wings were placed in a figure-of-8 bandage after surgery. The specimens harvested for angiography were decalcified, radiographed, and sectioned for H&E-stained tissue slides. Humeruses harvested for histomorphometry were cross-sectioned for tissue slides, which were measured, using a morphometric analyzing system for original and new bone areas. RESULTS: A continuous intramedullary circulation was not present at any point in the healing process, although 2 of the 42-day-old fractures had a bridging callus. Quantitatively, the periosteal surface formed the largest amount of callus, though the endosteal surface was also active. CONCLUSIONS: Reformation of the intramedullary circulation may not be imperative for osseous union of the pigeon humerus. Fluorochrome labels cannot be accurately measured at the fracture site. However, subjective evaluation of the endosteal surface indicates it is active during the fracture-healing process even though the periosteal surface provides the largest amount of callus formation. CLINICAL RELEVANCE: Figure-of-8 coaptation is contra-indicated for humeral fractures. The endosteal surface's contribution to the healing process should be considered when avian humeral fractures are stabilized.

Angiography↗

PubMed1992

An outbreak of melioidosis in imported primates in Britain.

An outbreak of melioidosis, a bacterial infection caused by Pseudomonas pseudomallei, was identified in a batch of feral cynomolgus monkeys (Macaca fascicularis) imported to Britain from the Philippines. Thirteen confirmed or possible cases occurred among a batch of 50 animals. Subsequent investigations revealed that the infection was uncommon among imported primates from a variety of sources, although three other cases were identified in monkeys imported from Indonesia. The majority of the affected monkeys had splenic abscesses, and hepatic abscesses and infections of the soft tissues and skin were also frequently observed. Most of the infected animals had no clinical signs despite extensive abscesses, and the presence of infection was only suspected when they were shown to have serum antibodies to P pseudomallei by an enzyme-linked immunosorbent assay. Although there was no evidence of cross infection of other animals or human handlers, this outbreak is a reminder of the dangers of working with wild-caught primates and the potential for the establishment of environmental foci of melioidosis.

Abscess↗

PubMed1992

Comparison of sensitivities of three commercial MRC-5 cell lines grown in shell vials to cytomegalovirus and responses to enhancing agents.

MRC-5 cells grown in shell vials from three suppliers (Whittaker Bioproducts, Bartels, and ViroMed) were evaluated for sensitivity to human cytomegalovirus. Previous studies done in our laboratory showed that treatment of the cells with dexamethasone (DEX) and dimethyl sulfoxide (DMSO) or these agents plus calcium improved the sensitivity of cells from Whittaker. In this study, we compared the response of the Whittaker cells with those of the cells from Bartels and ViroMed, both treated and untreated, when tested with strain AD169, a strain of wild-type virus, and 41 clinical specimens from various sources. A progressive improvement in sensitivity to AD169 and the wild-type virus was seen for all cell lines with DEX-DSMO and DEX-DMSO-calcium treatments, although even untreated, the Whittaker cells were much more sensitive. Detection of most of the positive clinical specimens was enhanced by both treatments with the Whittaker cells. DEX-DMSO had little or no effect on Bartels or ViroMed cells, while DEX-DMSO-calcium usually effected some increase in the number of inclusions. Six specimens were recovered only on Whittaker cells. Protein studies were done on all groups to determine the effect, if any, of the treatments on the metabolism of the cells.

Cell Line↗

PubMed1990

Enhancement by calcium of the detection of cytomegalovirus in cells treated with dexamethasone and dimethyl sulfoxide.

MRC-5 cultures treated with dexamethasone, dimethyl sulfoxide, and calcium were compared with untreated cultures and cultures treated with dexamethasone and dimethyl sulfoxide for the detection of human cytomegalovirus by the shell vial method. The addition of calcium resulted in significantly increased growth of human cytomegalovirus AD169. Protein studies and cell counts showed renewed cell proliferation in the treated cultures. When low-titer clinical specimens were retested, 27.5% of all positives revealed were found only on the vials treated with calcium. In a group of freshly tested specimens, the calcium-treated group accounted for 20% of the positives.

Calcium↗

PubMed1989

Increased detection of herpes simplex virus in MRC-5 cells treated with dimethyl sulfoxide and dexamethasone.

Treatment of MRC-5 cells with dexamethasone, dimethyl sulfoxide, or a combination of the two enhanced the detection of herpes simplex virus by three- to fourfold in these cells. Fluorescent plaques were noticeably larger on cover slips treated with the enhancing agents. Low-positive clinical specimens were stored and tested in parallel in treated and untreated shell vials, and 6 to 40% of these stained positive in the treated cultures but not in the untreated controls. In standard tube cultures, cytopathic effect began earlier and was more extensive in treated tubes.

Antigens, Viral↗

PubMed1988

Enhanced detection of cytomegalovirus in confluent MRC-5 cells treated with dexamethasone and dimethyl sulfoxide.

Optimum growth conditions for human cytomegalovirus (HCMV) include the use of subconfluent, actively growing cultures of human embryonic fibroblasts. Many clinical virology laboratories, however, use tissue culture cells from commercial sources. These cells are usually confluent, static cultures that tend to be less sensitive to viral infection. To determine whether dimethyl sulfoxide (DMSO) or dexamethasone (DEX), which are known enhancers of HCMV, facilitates the detection of the virus in confluent cells, we tested both HCMV AD169 and a number of clinical specimens suspected to contain HCMV on MRC-5 cells in both shell vials and conventional tube cultures. We found that, in the shell vial test, treatment of the cultures with either DMSO or DEX before and after inoculation increased the number of cells staining positive by three- to sixfold compared with untreated controls. Best results were obtained by pretreating the cultures with DEX alone and by treating the cultures with a combination of DEX and 1% DMSO postinfection. In the conventional MRC-5 culture tubes, treatment with the reagents resulted in the more rapid appearance of cytopathic effect and a more extensive infection of the cell sheet. The experimental findings indicate that the enhancing effect of DEX is attributable mainly to the increased production of a cellular mRNA during the period preceding viral infection.

Cell Line↗

PubMed1988

Increased detection rate for varicella-zoster virus with combination of two techniques.

Standard cell culture and centrifugation culture were compared for the isolation of varicella-zoster virus from 337 clinical specimens. Of a total of 85 (25%) positive specimens, 67 (78.8%) were positive by centrifugation culture alone and 18 (21.2%) were positive by both methods. When epithelial cells from the specimen were included in the vial inoculum, these cells stained positive and increased the varicella-zoster virus detection rate by 30%.

Cell Line↗

PubMed1987

Phytohemagglutinin-enhanced hybrid colony formation by cells from aged mice: expression of TH 4Mod-1 mouse locus in human-mouse hybrids.

Cells from a continuous human line and freshly isolated cells from old adult mice heterozygous at the Mod-1 locus were fused in the presence of polyethylene glycol (PEG). The production of hybrid cells, as a function of PEG concentration in the presence and absence of phytohemagglutinin (PHA), was measured by cell survival and proliferation on selective medium. The incorporation of PHA into the fusion mixture allowed cell fusion to take place at nontoxic concentrations of PEG. PHA increased the frequency of cell fusion and increased the production of viable hybrid cells from 138- to over 2800-fold depending on cell type. The results suggest that the procedure may have broad application in promoting the fusion of cells sensitive to PEG. Clones were analyzed for isozymes of malic enzyme and glucose-6-phosphate dehydrogenase. The expression of the gene encoding X-linked mouse glucose-6-phosphate dehydrogenase confirmed that the cells were hybrids. These cells lost other mouse isozymes rapidly. In those clones in which the mouse malic enzyme gene was expressed, the product of Mod-1a was detected significantly more frequently than that of Mod-1b.

Aging↗

PubMed1981

Controller anaesthesia: an approach using patient characteristics identified during uptake.

A system to control the alveolar anaesthetic concentration of patients undergoing halothane anaesthesia with controlled ventilation is described. Parameters characterizing the alveolar concentration response are determined on-line from breath-by-breath measurement of the inspired and end-tidal concentrations and the mixed venous anaesthetic partial pressure is estimated throughout the procedure. The method does not depend on the use of reference models or pre-programming and the inspired concentration required to control the alveolar concentration is determined as induction proceeds. Results using both computer simulations and data from patients undergoing routine clinical anaesthesia are analysed. Off-line verification results illustrate the operation of the technique and in 20 cases the inspired concentration, as controlled by the anaesthetist, was compared with that predicted by the automated system. These results indicate the feasibility of the system as a method for the control of anaesthesia.

Anesthesia, Inhalation↗

PubMed1979

Breath-by-breath halothane monitoring during anaesthesia. A study in children.

The use of a halothane meter in routine paediatric anaesthesia with controlled ventilation is described. The results demonstrate the accuracy achieved in the control of the alveolar halothane concentration. Measurement of the alveolar halothane concentration revealed responses to surgical stimulation otherwise obscured by neuromuscular blockade, and this may indicate insufficient depth of anaesthesia.

Adolescent↗

PubMed1978

A rapid-response u.v. halothane meter.

The design and performance characteristics of an instrument for monitoring halothane concentrations which operates on the principle of the absorption of u.v. light are described. The innovation is that the entire exhaled breath passes through the sample cell, enabling the breath-by-breath halothane concentration to be measured accurately and instantaneously. Stablized power supplies, solid-state circuitry and filtering make the instrument stable and selective. A valve prevents rebreathing of gas exposed previously to u.v. light in the sample cell. Inspired and end-tidal concentrations are displayed digitally and an analog output is available also. Zero and gain drift were negligible after an initial settling period, and interference from other respiratory gases was not detectable. The monitor is suitable for use during anaesthesia for adults and children.

Adult↗