PubMed Health⌕ Search

Biomedical subjects

J S Price

Publications and source records attributed to J S Price.

At least 19 recordsLinked to original sources
PubMed1995

Age related changes in biochemical markers of bone metabolism in horses.

Biochemical markers of bone metabolism were analysed in serum samples obtained from 60 horses with no history of orthopaedic disease (age 3 months-20 years). Serum levels of the carboxyterminal propeptide of type I procollagen (PICP), a marker of bone formation and the pyridinoline cross linked telopeptide domain of type I collagen (ICTP), a putative marker of bone resorption, were measured by radioimmunoassay (RIA). Serum levels of the bone specific isoenzyme of alkaline phosphatase (BALP), another marker of bone formation, were measured by a wheatgerm agglutinin affinity (WGA) method. Total alkaline phosphatase levels were also determined. Serum levels of PICP were significantly correlated with bone ALP (r = 0.78, P < 0.0001) and ICTP (r = 0.87, P < 0.0001). ICTP levels also correlated significantly with bone ALP (r = 0.81, P < 0.0001). However, total alkaline phosphatase did not correlate significantly with PICP, ICTP and BALP in horses over 1 year of age. There was an inverse correlation between serum levels of all biochemical markers and age of animals, with the most significant changes seen over the first 2 years. In animals less than 1 year of age, the reference ranges (mean +/- s.d. 1.96) were as follows: PICP 1216-2666 micrograms/l, ICTP 13.8-26.7 micrograms/l, bone ALP 134-288 u/l and total ALP 223-498 u/l. In 2-year-olds, the equivalent reference ranges were: PICP 550-1472 micrograms/l, ICTP 7.96-22.8 micrograms/l, bone ALP 32.7-125 u/l and total ALP 134-238 u/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1994

Cells cultured from the growing tip of red deer antler express alkaline phosphatase and proliferate in response to insulin-like growth factor-I.

Deer antler growth provides a unique natural model of rapid and complete bone regeneration. In this study, the distal antler tips of male red deer (Cervus elaphus) were collected post-mortem during the annual growth period (April-August), and an in vitro system established for the culture of cells from three regions; the inner layer of the perichondrium, the reserve mesenchyme and the cartilage zone. Alkaline phosphatase (ALP) expression by cultured cells, as demonstrated by enzyme histochemistry and biochemical assay, reflected the stage of cellular differentiation. ALP activity was highest in cells cultured from the hypertrophic cartilage region (3.6 +/- 0.2 mumol/micrograms cell protein/minute), and lowest in undifferentiated mesenchymal cells (0.3 +/- 0.01 mumol/microgram cell protein/minute). ALP expression was lost with passage in culture. Levels of ALP activity in cultured cells correlated with the pattern and extent of enzyme expression in tissue sections as demonstrated by histochemical staining. Insulin-like growth factor (IGF)-I (10(-9)M-10(-7)M) was found to be mitogenic for cultured cells from all three zones as shown by increased incorporation of [3H]thymidine into DNA. These results demonstrate that cells from three different regions of the antler tip can be maintained in culture, and that antler cells share certain phenotypic characteristics of growth plate chondrocytes. These data provide further evidence of a role for IGF-1 in the regulation of antler growth. Antler regrowth is a potentially useful model for the study of the factors that regulate bone formation.

Alkaline Phosphatase↗
PubMed1994

The cell biology of bone growth.

The field of bone cell biology is clearly of relevance to the problem of stunting in children, as in the final analysis the cells of the growing long bone are the ultimate 'regulators'. It is the alterations in the functions of these cells that manifests as a reduction in height. Normal longitudinal growth is achieved by the coordinated recruitment, proliferation, differentiation, maturation and eventual death of the cells of growth plate and bone. Cellular activity is closely regulated by endocrine factors acting directly or indirectly, with factors produced locally and stored within the bone and cartilage microenvironment having a critical role in intercellular communication. Disruption of any of these processes can lead to growth disturbances, since it only requires a defect in a single gene to have profound effects. Studies in recent years have shed light on the biochemical and molecular effects of cytokines and growth factors and have shown that these regulatory molecules may mediate the effects of certain hormones important in controlling growth. However, the complex interrelationship of these molecules is still not clear. Notwithstanding, understanding of the mechanisms involved in bone remodelling is increasing, as this area attracts much research because of the high incidence of metabolic bone disease in Western society. Although studies of adult bone remodelling are of relevance, there is a requirement for increased research directed specifically at the mechanisms of endochondral ossification and its regulation. Longitudinal bone growth is a challenge to the cell biologist, since it is an accelerated cycle of cellular division and differentiation, within which it is not easy to separate events temporally and spatially. In addition, different regulatory mechanisms are probably important at different stages of growth. Another difficulty impeding progress in this field is the lack of appropriate animal models for research. Much information has come from studies involving rodents, and species differences must always be taken into account. Larger mammals such as the growing piglet or the calf are probably more appropriate for the study of postnatal longitudinal growth in man. If the mechanisms of stunting are to be established at a cellular level, a number of approaches need to be considered. Studies need to be designed using more appropriate animal models, and conditions such as nutritional intake, immunological challenges, chronic intestinal diseases and mechanical loading need to be manipulated. Any effects on longitudinal growth may then be studied temporally and correlated with non-invasive measurements including assays of hormones, cytokines, growth factors and proteins known to regulate their activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Bone Development↗
PubMed1993

Physical aspects of photostimulable phosphor computed radiography.

Currently photostimulable phosphor computed radiography (PPCR) promises to be the digital X-ray image acquisition technology of choice for classical radiography (i.e. X-ray examinations of natural anatomy). For the last two years we have been carrying out a physical evaluation of modern PPCR technology and some of our findings relevant to general radiographic applications are reviewed here. Topics covered include the function of the auto-reader system and the reliability of image reproduction, the radiation exposure requirement and physical image quality. The latter is based upon both objective and subjective measures of image quality. These studies have yielded a favourable comparison of the image quality of modern PPCR technology with that of medium-speed and fast radiographic screen-film combinations. The major advantages of PPCR appear to be the maintenance of high imaging efficiency (DQE) over a much wider range of signal levels than film and consistent image acquisition and presentation independent of exposure level. In general radiographic applications no major limitations due to the comparatively modest limiting spatial resolution of PPCR [maximum limiting resolution = 5 line-pair mm-1] have been experienced. Digital image enhancement is a central element of PPCR image reproduction. The authors believe that advances in image enhancement algorithms remain a potential area for further improving the presented quality of PPCR images.

Image Processing, Computer-Assisted↗
PubMed1991

Neuropeptide Y (NPY) metabolism by endopeptidase-2 hinders characterization of NPY receptors in rat kidney.

1. Despite the observation of pharmacological responses to neuropeptide Y (NPY) in mammalian kidneys, there are species differences in the ease with which specific NPY binding sites can be demonstrated; we have investigated whether this can be explained by differential metabolism of NPY by a membrane-bound peptidase. 2. NPY receptors were identified on cell membranes isolated from the rabbit kidney (KD = 97 +/- 16 pM, Bmax = 290 +/- 30 fmol mg-1 protein), and this preparation did not degrade [125I]-NPY. However, a similar preparation of cell membranes from the rat kidney exhibited a much lower apparent receptor affinity (IC50 approximately 30 nM); these membranes rapidly degraded [125I]-NPY to fragments which did not bind NPY receptors in either tissue. 3. [125I]-NPY binding sites were revealed in the rat kidney when degradation was inhibited by insulin B chain. Chelating agents also inhibited degradation, but interfered with receptor binding. Binding sites could not be demonstrated in sections of rat kidney, even in the presence of insulin B chain. 4. The difference in degradative activity between rat and rabbit renal cell membranes, inhibition of degradation by chelating agents and insulin B chain, and insensitivity to phosphoramidon suggest that the enzyme responsible was endopeptidase-2, and this was confirmed by comparing the hydrolysis of [125I]-NPY by purified enzyme with rat renal tissue. Activity of this enzyme explains the difficulties encountered demonstrating receptors in the rat kidney. 5. Renal cell membranes from the mouse digested [125I]-NPY in a similar manner and this may be due to the closely related enzyme, meprin. NPY degradation has not previously been reported. The results suggest that NPY should be added to the list of peptides sensitive to these enzymes.

Animals↗
PubMed1991

Change or homeostasis? A systems theory approach to depression.

Looking at the onset of depressive states in linear terms, there is often a problem of distinguishing cause and effect: did the adverse life-events cause the depression, or did the depression cause the adverse life-events? If we abandon linear thinking and look at depression in systemic terms, the problem of cause and effect disappears, but it is replaced by another problem: is the patient/environment system characterized by homeostasis or change? Some depressed patients seem to be spiralling down towards disaster. Others seem to be stuck in a rut. In systems terms, can depression be at the same time an agent of change and an agent of stasis (or even homeostasis)? The paradox can be resolved if we postulate that the function of depression is to reconcile the individual to an involuntarily subordinate social role; depression which reconciles to a pre-existing subordinate position has static properties; depression which mediates a switch to a subordinate position from a previously dominant position has properties of systemic change.

Depressive Disorder↗
PubMed1990

125I-neuropeptide Y binding activity of pig spleen cell membranes: effect of solubilisation.

Crude preparations of pig spleen cell membranes were obtained by differential centrifugation. 125I-NPY bound specifically to these membranes with a KD of 56 +/- 13 pM and Bmax of 44 +/- 4.0 fmols/mg protein. After treatment with 1% CHAPS* and 10 mM 2-mercaptoethanol in the presence of 2 microM leupeptin, 2 microM pepstatin A, 10 microM phosphoramidon, 200 microM PMSF and 0.1% bacitracin, followed by centrifugation at 100,000 g a soluble preparation was obtained that contained a single population of specific 125I-NPY binding sites. The KD of the soluble receptor was significantly higher at 1.38 +/- 0.2 nM (P less than 0.01) but the Bmax of 59.6 +/- 6.6 fmols/mg protein was similar (N.S.). This is the first description of a method for obtaining NPY receptors in soluble form and should enable their purification and characterisation, though the low affinity of the soluble receptor may reflect disruption of the ligand binding site upon removal of the receptor from the membrane.

Animals↗
PubMed1989

PCR origins.

Explore the source record for details and available documents.

DNA-Directed DNA Polymerase↗
PubMed1989

Self-rating.

Explore the source record for details and available documents.

Depressive Disorder↗
PubMed1987

Adrenaline causes potassium influx in skeletal muscle and potassium efflux in cardiac muscle in rats: the role of Na/K ATPase.

Previous in vitro evidence suggests that adrenaline causes K influx in skeletal muscle by stimulating a ouabain sensitive Na/K ATPase membrane pump. However in rabbits, adrenaline induced hypokalaemia was not significantly altered by pretreatment with digoxin (50 micrograms/kg). Rats were infused with adrenaline or saline after being given a tracer dose of 42KCl. Adrenaline caused a highly significant uptake of 42K in skeletal muscle and a decrease in 42K uptake in ventricle. Rats were also studied after receiving a high dose of digoxin (1.4 mg/kg) which by itself produced a significant increase in plasma K, a decrease in plasma Na and a decreased uptake of 42K in ventricle and lung. These results suggest that adequate widespread Na/K ATPase inhibition had been achieved by this dose of digoxin but despite this, adrenaline still caused hypokalaemia and also still caused significant 42K tissue uptake by skeletal muscle. These results suggest that adrenaline causes K influx by skeletal muscle and K efflux by cardiac tissue. Furthermore, the former mechanism was not inhibited by pretreatment with digoxin.

Animals↗
PubMed1981

Alkaline protease from Neurospora crassa. Purification and partial characterization.

A simple purification procedure has been developed for the extracellular alkaline protease from Neurospora crassa. Key steps in the purification were: 1) the choice of gelatin as the protein inducer, which induces optimally at a much lower concentration than other commonly employed protein inducers; 2) heat treatment, during which the inducer is digested by the protease; and 3) a concentration step that eliminates the usual precipitation procedures and removes much of the digested protein inducer. These procedures were followed by routine ion exchange chromatography and gel filtration. The preparation was homogeneous, as determined by gel electrophoresis and ultracentrifugal analyses. A molecular weight of approximately 30,500 was determined by amino acid analysis, gel electrophoresis, and sedimentation equilibrium. The protease has 100% activity from pH 6.0 to 10.0, is heat labile above 45 degrees C, and susceptible to autodigestion. Hydrolysis of the beta chain from insulin indicates a preferential cleavage on the carboxyl group side of neutral and aromatic amino acids.

Amino Acid Sequence↗
PubMed1978

Mechanism of the antipsychotic effect in the treatment of acute schizophrenia.

In a double-blind trial in which 45 patients with acute schizophrenia took part the alpha-isomer of flupenthixol (which blocks the dopamine receptor) was found to be significantly more effective than both beta-flupenthixol (which does not) and placebo. The drug effect was confined to the "positive" symptoms--delusions, hallucinations, and though disorder--and appeared only in the 3rd and 4th weeks of the trial. It was as great in patients with evidence of deterioration (Feighner-positive patients) as in patients without deterioration and was less in patients who had affective disturbance in addition to schizophrenia symptoms. The findings are consistent with the hypothesis that dopamine-receptor blockade is the only requirement for antipsychotic activity and suggest that the antipsychotic effect occurs in patients with typically schizophrenic illnesses but may be limited to positive symptoms.

Acute Disease↗