Search PubMed⌕ Search

Biomedical subjects

G L Jones

Publications and source records attributed to G L Jones.

At least 37 records · Page 2Linked to original sources
PubMed2000

Haemolysis of human and sheep red blood cells in glycerol media: the effect of pH and the role of band 3.

Haemolysis of red blood cells (RBC) in glycerol media may be measured spectrophotometrically. The haemolytic process in a rapid phase obeys a first order rate law. The rate constant expresses the rate of haemolysis. To gain a better understanding of the mechanism of haemolysis in glycerol media, the effects of pH and band 3 inhibitors on the rate of haemolysis in human and sheep RBC were observed. Over the pH range used (pH 5.8-10.0), the rate of haemolysis decreased with increase in pH in sheep RBC. By contrast, the rate of haemolysis increased from pH 5.8 to 6.4 and decreased above pH 6.4 in human RBC. The different effects of pH on the rate of haemolysis are due to inhibition of glycerol permeability by H(+) in human RBC but not in sheep RBC. This is supported by the different effects of temperature and Cu(2+) on the rate of haemolysis in human and sheep RBC. We did not observe complete inhibition of haemolysis by the classical band 3 inhibitor, 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). Another band 3 inhibitor 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS) showed only weak inhibition. Phenylgloxal (PG), another band 3 inhibitor, had no effect whatsoever on the rate of haemolysis. These results indicate that the anion pathway of band 3 is not the preferred route of transport of glycerol in mammalian RBC.

Animals↗
PubMed2000

Maintenance energy requirements and the effect of diet on performance of racing Greyhounds.

OBJECTIVES: To determine maintenance energy requirements and effect of diet on performance of racing Greyhounds. ANIMALS: 7 adult racing Greyhounds. PROCEDURE: Dogs were fed a higher fat and protein (HFP) or a lower fat and protein (LFP) diet for 8 weeks in a crossover design. Dogs were exercised for 15 minutes twice daily in a paddock and raced 500 m twice weekly. Blood gas, hematologic, and serum biochemical analyses were performed before and after racing, and race times were compared at the end of each diet period. RESULTS: Mean race time was significantly shorter (32.81+/-0.65 seconds vs. 33.05+/-0.71 seconds), and mean racing speed over 500 m was significantly faster (15.25+/-0.30 vs. 15.13+/-0.30 m x s(-1)) when dogs were fed the HFP diet than when they were fed the LFP diet. Diet had little or no effect on results of blood gas, hematologic, and serum biochemical analyses, except that Hct was 4% greater before and after racing when the HFP diet was fed than when the LFP diet was fed. Mean SD metabolizable energy intake from weeks 1 through 16 was 155+/-9 kcal x kg(-0.75) x d(-1). CONCLUSIONS AND CLINICAL RELEVANCE: Racing Greyhounds ran faster when fed a diet containing higher fat and protein and lower carbohydrate contents. Their maintenance metabolizable energy requirement was slightly higher than that of moderately active dogs.

Animal Feed↗
PubMed2000

Nonunion of the fractured clavicle: evaluation, etiology, and treatment.

Although often viewed as benign injuries, clavicular fractures can lead to complications, particularly nonunions. The nonunion rate has been reported to be between 0.1% and 15%. Contributing factors to nonunion include severe initial trauma, marked initial displacement and shortening, soft tissue interposition, primary open reduction and internal fixation, refracture, open fracture, polytrauma, and inadequate initial immobilization. A clavicular nonunion is rarely asymptomatic and often results in disability from pain at the site of nonunion, altered shoulder mechanics, or a compression lesion involving the underlying brachial plexus or vascular structures. Treatment options include nonsurgical management, salvage procedures, and reconstructive procedures. The present goal is to obtain union with reconstructive procedures. The fixation methods described range from external fixation to plate and screw osteosynthesis. We prefer open reduction and internal fixation with plates and screws and with intercalary tricorticocancellous grafts to obtain union and restore the clavicle to its normal length.

Bone Transplantation↗
PubMed1999

Age-related attenuation in the expression of the major heat shock proteins in human peripheral lymphocytes.

A defining characteristic of human ageing is the reduced ability to maintain homeostasis in the face of adverse environmental stresses. This progressive impairment may be a major cause for the increased incidence of infections, and general morbidity and mortality in the elderly. Heat shock proteins (hsps) or stress proteins, induced in response to hyperthermia and to various other physical, chemical and biological stressors, are often also expressed constitutively at a lower level and perform many essential functions in the cell. Here we investigate age-related changes in the heat induced expression of a comprehensive range of hsps at the translational level using primary human peripheral lymphocytes in short term culture. Our study reveals age-related attenuation in the response of the well characterised up-regulated molecular chaperone system hsp 70, the steroid-receptor binding hsp 90 and the chaperonin hsp 60. A diminution with age is also demonstrated in the heat induced response of hsps 105, 56, 47, 40, 27, and 16. Differentially down-regulated proteins at 100, 38, and 18 kDa were also noted.

Adolescent↗
PubMed1999

A comprehensive analysis of heat shock protein synthesis in human peripheral lymphocytes: the effect of penicillin/streptomycin.

A reliable experimental procedure is described for the simultaneous characterisation of a comprehensive range of heat shock proteins (hsps) in human peripheral lymphocytes. In this system, a mild heat shock from 37 to 42 degrees C for 1 h induced the synthesis of hsps 105, 90, 70, 60, 57, 47, 40, 27 and 16. Densitometric analyses of 35[S]-methionine labelled protein gels indicated that levels of these hsps peaked at 3 to 4 h, following post-heat shock recovery at 37 degrees C. The presence of penicillin and streptomycin in the cell culture medium, appeared to have little effect on the kinetics of hsp synthesis. The present method can be used for relatively small blood samples and its relative ease of application and reproducibility make it appropriate for screening the expression of hsps in human lymphocytes from a range of individuals.

Adolescent↗
PubMed1997

A comparative electrophoretic analysis of mammalian hair and avian feather proteins.

An improved one-dimensional sodium dodecyl sulphate separation has allowed a detailed electrophoretic comparison of the proteins that constitute hairs and feathers isolated from various representative samples of mammalian, both placental and marsupial and avian species. The proteins from various species were S-carboxymethylated using labelled (14C)-iodoacetic acid and detected both by Coomassie stain and fluorography. Proteins from mammalian species were compared with respect to their molecular masses and relative cysteine content using laser densitometry of both Coomassie stained gels and fluorographs of 14C labelled gels. These results may be quite useful forensically as an adjunct to fibre analysis.

Animals↗
PubMed1996

Effect of context and adjuvant on the immunogenicity of recombinant proteins and peptide conjugates derived from the polymorphic malarial surface antigen MSA2.

We have identified a 51 kDa glycosylated myristylated merozoite surface antigen (MSA2) as the target of a number of monoclonal antibodies which inhibit in vitro invasion of the human malarial parasite Plasmodium falciparum. This antigen has been shown to exist in a limited number of strain specific forms but despite wide variation in the sequences of the internal repeat regions both N and C terminal elements of the protein are almost totally conserved. Accordingly, we prepared a large number of overlapping peptide constructs and demonstrated that one peptide SNTFINNA (E71) from the N terminus and two peptides, QHGHMHGS (G5) and NTSDSQKE (G12) from the C terminus could, when suitably conjoined to the carrier protein diphtheria toxoid (DT), elicit antibodies reactive with MSA2 from diverse strains of P. falciparum. Here we compare the immunogenicity of these peptide constructs with two recombinant proteins containing the entire amino acid sequence of MSA2 from the FCQ-27/PNG strain (1609) and the 3D7 strain (1623). We have formulated these recombinant and peptide antigens with Freund's adjuvant, Alum and Algammulin. Both recombinant and peptide antigens elicit high titre antibodies when tested by ELISA against the immunogens themselves. Although both recombinant proteins include the constant region peptide sequences E71, G5 and G12, the extent of ELISA cross reaction between antibody raised against recombinant and peptide antigen or antibody raised against peptide and recombinant antigen is small and sporadic, and depends to an extent on the adjuvant employed. Antisera against both recombinant proteins 1609 and 1623 detected either recombinant on Western blots, as well as detecting native MSA2 in whole protein extracts from both FCQ-27/PNG and 3D7 strains. Antisera against peptide construct E71 recognized recombinant 1609 but not 1623 but recognized the native MSA2 in both strains studied. Antisera against peptide construct G5 showed a similar pattern of recognition but also detected recombinant 1623 on Western blotting. These results emphasize the importance of context and adjuvant on the ability of selected immunogenic epitopes to elicit antibodies appropriately directed against the native antigen.

Adjuvants, Immunologic↗
PubMed1996

Peptide mapping of S-carboxymethylated hair and feather proteins using two-dimensional electrophoresis.

The aim of this work was to develop a two-dimensional electrophoretic method for the multiple simultaneous peptide mapping of a broad spectrum of human and animal hair and avian feather proteins. The 14C labelled S-carboxymethylated proteins of hair and feather were separated in one dimension by sodium dodecyl sulphate-polyacrylamide slab gel electrophoresis and stained with Coomassie Blue. Each of the gel lanes containing the separated hair or feather proteins from one individual was cut and transferred at right angles on to a second slab gel. A solution of trypsin (5 micrograms/ml) in stacking gel buffer was poured on to the gel lane. Partial proteolysis of the hair or feather proteins proceeded in situ while the stacking gel buffer set. The second dimension of electrophoresis followed by staining and/or fluorography showed a characteristic pattern of peptides of proteins in the form of spots derived from each individual protein, leaving undigested proteins well separated on the diagonal. The protease digestion pattern was reproducible and characteristic of each sample. We were able to establish a finer peptide signature, for individual samples containing a mixture of many proteins, than was hitherto possible with previously published two-dimensional electrophoretic techniques. It was concluded that this technique may be of use in future evolutionary, ontogenetic and forensic studies using hair and feathers as a biological source material.

Animals↗
PubMed1996

Venus and Freud: an educational opportunity?

OBJECTIVE: To discuss the importance of genitourinary medicine as a core component for a new problem based medical undergraduate curriculum and to describe the advantages of consensus group method as a means of identifying learning objectives for an integrated course. METHODS: A group of experts in the field of sexual health was convened around the module on sexual health. It was led by a genitourinary specialist and aided by a curriculum facilitator. Group contributors represented a wide variety of disciplines and included a medical student. The group met on three occasions for 1.5 hours. RESULTS: The identified learning objectives are presented under the course themes. The values and relevance of the individual objectives are discussed with particular reference to an integrated curriculum which combines clinical and basic science in a problem based learning (PBL) format. The communication skills and attitudes necessary to take a competent sexual history are stressed. Links with other relevant modules in the PBL curriculum are described to show how the topic of sexual health develops throughout the course. Learning methods, resources and assessment procedures are also outlined. CONCLUSION: The educational potential of sexual health and behaviour as a core topic for a novel integrated course is considerable and merits a greater importance than it appears to receive in current undergraduate courses.

Education, Medical, Undergraduate↗
PubMed1995

High resolution one-dimensional electrophoretic separation and partial characterisation of human head hair proteins.

A reproducible, rapid procedure for the extraction, labelling and separation of human hair proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) has been developed. Hair proteins were extracted in 8 M urea, containing 0.2 M mercaptoethanol, followed by sonication. Extracts were neutralised with Tris and incubated with either labelled (14C) or unlabelled iodoacetic acid to S-carboxymethylate cysteine groups. Proteins were separated on 12.5% SDS-polyacrylamide gels and gels stained with Coomassie Brilliant Blue and/or silver nitrate to reveal major protein bands. Gels were then treated with a fluorographic agent, dried and autoradiographed to reveal major sites of S-carboxymethylation. A given gel was scanned by laser densitometry after Coomassie and/or silver stain to quantitate the protein content of each major protein zone. An autoradiogram of the same gel was scanned to estimate the cysteine content of each major zone. In this way it was possible to partially characterise rapidly and reproducibly many different protein zones in different individual samples on one gel at the same time. By calculating the ratio of autoradiograph absorbance to Coomassie Blue absorbance, protein zones could be assigned to four different categories, viz: very high cysteine (VHC) proteins, high cysteine (HC) proteins, low cysteine (LC) proteins and very low cysteine (VLC) proteins. The method described is reproducible, rapid and inexpensive enough to be suitable for mass screening. Overall the results were more informative than previously reported one-dimensional separations and indeed this technique may well be more suited to forensic and/or population investigations than the much more laborious and time-consuming two-dimensional techniques.

Autoradiography↗
PubMed1994

Strain profiles for circular cell culture plates containing flexible surfaces employed to mechanically deform cells in vitro.

Cells in the body are constantly subjected to cyclic mechanical deformation involving tension, compression, or shear strain or all three. A mechanical loading system which deforms cultured cells in vitro was analyzed in order to quantify the deformation or strain to which the cells are subjected. The dynamic system utilizes vacuum pressure to deform a circular silicone rubber substrate on which cells are cultured. These thick circular growth surfaces or plates are formed in the bottoms of the wells of 6-well culture plates. An axisymmetric model was formulated and analyzed using rectangular hyperelastic elements in a finite element analysis (FEA) software package. The thick circular plate has some disadvantages such as difficulty in observing cells and a nonhomogeneous strain profile which is maximum at the periphery and minimal at the center. A thinner circular surface (a thin plate) was also investigated in order to provide a more homogeneous strain profile. The radial strain on the thick circular plate, as determined by FEA, was nonlinear with a peak strain value of 0.30 (vacuum pressure of 22 kPa) about three-quarters of the distance from the center to the edge. In contrast, the radial strain of the thin circular plate was moderately constant across the surface. The circumferential strain for both of these models was less than the radial strain except for the center where they are equal. Avian tendon cells were cultured on the surface of a thick plate and exposed to cyclic strains for 24 h at a rate of 0.17 Hz and observed for cellular alignment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Structural organisation of band 3 in Melanesian ovalocytes.

The diffusional freedom of human erythrocyte band 3 (anion exchanger 1) has been measured in membranes from normocytic and ovalocytic erythrocytes. A dramatic reorganisation of band 3 in the ovalocyte membranes is indicated by a markedly restricted rotational mobility. Extraction of spectrin from erythrocyte membranes had no effect on normocyte band 3 mobility, but partially relieved the restrictions on ovalocyte band 3 mobility. Further removal of ankyrin and band 4.2 resulted in an increase in the rotational mobility of both ovalocyte and normocyte band 3 to similar levels. The results suggest that the molecular basis of the unusual shape and decreased deformability of ovalocytes resides in an altered interaction of band 3 with one or more of the peripheral proteins. We present a model which illustrates a possible role for band 3 aggregation in controlling erythrocyte deformability.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1993

Mice immunized with a synthetic peptide construct corresponding to an epitope present on a Plasmodium falciparum antigen are protected against Plasmodium chabaudi challenge.

Inhibitory monoclonal antibody (MoAb) 8E7/55 recognizes a parasitophorous vacuole membrane (PVM) antigen in Plasmodium falciparum. Previous studies have identified the epitope, DNNLVSGP, recognized by the MoAb. A synthetic peptide containing this sequence was synthesized and coupled to diphtheria toxoid (DT) and was found capable of generating antibodies when used as an immunogen in mice which recognize the native antigen exp-1. In this study we demonstrate the ability of the MoAb and antisera generated against the peptide construct to recognize a 54 kD PVM antigen in Plasmodium chabaudi. The P. chabaudi antigen is synthesized in trophozoites and released to the surrounding culture media outside the parasitized erythrocyte. Mice immunized with the peptide conjugate are protected when challenged with a lethal strain of P. chabaudi. Protection in the mice correlated with the antibody titre prior to challenge. If the PVM antigen from P. chabaudi is a homologue of exp-1 from P. falciparum, then these experiments may provide a guide to the antibody titres required in human trials before antibody mediated protection could be expected. The discovery that a PVM localized antigen is secreted into the surrounding in vitro culture media provides us with a valuable model system for further investigation of protein trafficking pathways in malaria-infected erythrocytes.

Amino Acid Sequence↗
PubMed1993

Effect of ozone exposure in vivo on response of bronchial rings in vitro: role of intracellular Ca2+.

In this study we investigated the role of intracellular Ca2+ in ozone- (O3) induced airway hyperresponsiveness. Acetylcholine-induced airway responses were measured before and after inhalation of O3 (3 ppm, 30 min) or dry air. In vitro experiments were performed with intact ring segments of third- to fifth-order bronchi. Bronchial responses to carbachol (CCh) were evaluated in Krebs solution (2.5 mM Ca2+) and in Ca(2+)-free [0.1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)] Krebs solution with or without indomethacin (IDM, 10(-5) M) and were expressed as percentage of the maximal KCl response (60 mM). Inhalation of O3, but not dry air, caused airway hyperresponsiveness to acetylcholine in vivo. Responses to 50% effective concentrations of CCh were similar in bronchial preparations from O3 and control animals (with or without IDM) in normal Krebs solution. In Ca(2+)-free solution, CCh induced a sustained (20-min) bronchial contraction. These contractions relaxed immediately when nifedipine or a high EGTA concentration was added to the organ bath. The sustained contraction was abolished when the tissues had been incubated with cyclopiazonic acid (10(-5) M), a novel inhibitor of the sarcoplasmic reticulum Ca2+ pump. After O3 exposure, responses of the bronchial smooth muscle (in Ca(2+)-free medium without IDM) were increased (P < 0.05) compared with controls during the first and second CCh stimulations. This O3-induced increase in response to CCh in Ca(2+)-free solution was abolished when the tissues were incubated with IDM.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Comparative study of the T cell response to two allelic forms of a malarial vaccine candidate protein.

T cell responses to two allelic forms of the merozoite surface Ag 2 (MSA2) of Plasmodium falciparum were mapped in mice using the rMSA2 proteins, Ag 1609 which has the sequence of the FCQ27/PNG strain and Ag 1615 which has the sequence of the Indochina 1 strain. Lymph node cells of BL/10 and B10.BR mice immunized with either Ag 1609 or Ag 1615 responded to both Ag in in vitro proliferation assays. Lymph node cells of BALB/c mice did not respond. The T cell determinants recognized by the responder strains were mapped to conserved and variant regions of these Ag using overlapping synthetic peptides. The determinants recognized by each mouse strain were distinct. Marked difference in sequence between the central regions of the two rMSA2 proteins did not affect antigenic processing of the conserved N and C terminal regions. Hence lymph node cells of BL/10 mice immunized with either Ag 1615 or Ag 1609 recognized an immunodominant T cell determinant at the highly conserved N terminal end within the sequence YSNTFINNAYNMSIR (peptide 3b) and B10.BR mice similarly immunized recognized an immunodominant determinant at the highly conserved C terminal within the sequence CTDGNKENCGAATSL (peptide 23). Several peptides identified as containing immunodominant T cell determinants specific to BL/10 mice induced peptide-specific T cells in both BL/10 and B10.BR mouse strains when used as immunogens. However, the ability of the peptide-primed T cells to proliferate in response to the rMSA2 proteins was confined to BL/10 mice. An example of this was observed with peptides 3b and N (KNESKYSNTFINNAYNMSIRRSMAN). Peptide N was able to prime B10.BR and BL/10 mice for an enhanced antibody response when these mice were subsequently immunized with Ag 1615 even though Ag 1615-specific T cell proliferation was not detected in B10.BR mice primed with N. The study concluded that 1) conserved sequences such as peptide N when used in vaccines may give rise to MSA2-specific memory Th cells amenable to boosting by subsequent exposure to all parasite strains and 2) peptide priming may be a useful pathway for inducing defined memory Th cells in a wider population and for preferentially inducing T dependent over T independent responses to some malarial Ag.

Amino Acid Sequence↗