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Biomedical subjects

C Pirie

Publications and source records attributed to C Pirie.

5 recordsLinked to original sources
PubMed2001

Treatment with a growth hormone secretagogue in a model of developing heart failure: effects on ventricular and myocyte function.

BACKGROUND: Exogenous administration of growth hormone (GH) and subsequently increased production of insulin-like growth factor-1 can influence left ventricular (LV) myocardial growth and geometry in the setting of congestive heart failure (CHF). This study determined the effects of an orally active GH secretagogue (GHS) treatment that causes a release of endogenous GH on LV function and myocyte contractility in a model of developing CHF. METHODS AND RESULTS: Pigs were randomly assigned to the following treatment groups: (1) chronic rapid pacing at 240 bpm for 3 weeks (n=11); (2) chronic rapid pacing and GHS (CP-424,391 at 10 mg x kg(-1) x d(-1), n=9); and (3) sham controls (n=8). In the untreated pacing CHF group, LV fractional shortening was reduced (21+/-2% versus 47+/-2%) and peak wall stress increased (364+/-21 versus 141+/-5 g/cm(2)) from normal control values (P:<0.05). In the GHS group, LV fractional shortening was higher (29+/-2%) and LV peak wall stress lower (187+/-126 g/cm(2)) than untreated CHF values (P:<0.05). With GHS treatment, the ratio of LV mass to body weight increased by 44% from untreated values. Steady-state myocyte velocity of shortening was reduced with pacing CHF compared with controls (38+/-1 versus 78+/-1 microm/s, P:<0.05) and was increased from pacing CHF values with GHS treatment (55+/-7 microm/s, P:<0.05). CONCLUSIONS: The improved LV pump function that occurred with GHS treatment in this model of CHF was most likely a result of favorable effects on LV myocardial remodeling and contractile processes. On the basis of these results, further studies are warranted to determine the potential role of GH secretagogues in the treatment of CHF.

Animals↗
PubMed1999

Effects of growth hormone supplementation on left ventricular morphology and myocyte function with the development of congestive heart failure.

BACKGROUND: Release of growth hormone (GH), putatively through alterations in insulin growth factor-1 (IGF-1) levels, has been implicated to influence left ventricular (LV) myocardial structure and function. The objective of this study was to determine contributory mechanisms by which GH supplementation may influence LV function with the development of congestive heart failure (CHF). METHODS AND RESULTS: Pigs were assigned to the following groups: (1) chronic pacing at 240 bpm for 3 weeks (n = 10), (2) chronic pacing and GH supplementation (200 microg x kg(-1) x d(-1), n = 10), and (3) controls (n = 8). GH treatment increased IGF-1 plasma levels by nearly 2.5-fold throughout the pacing protocol. In the untreated pacing CHF group, LV fractional shortening was reduced and peak wall stress increased. In the pacing CHF and GH groups, LV fractional shortening was higher and LV wall stress lower than untreated CHF values. Steady-state myocyte velocity of shortening was reduced with pacing CHF and was unchanged from CHF values with GH treatment. In the presence of 25 nmol/L isoproterenol, the change in myocyte shortening velocity was reduced in the untreated CHF group and increased in the GH-treated group. LV sarcoplasmic reticulum Ca(2+)-ATPase abundance was reduced with pacing CHF but was normalized with GH treatment. CONCLUSIONS: Short-term GH supplementation improved LV pump function in pacing CHF as a result of favorable effects on LV remodeling and contractile processes. Thus, GH supplementation may serve as a novel therapeutic modality in developing CHF.

Animals↗
PubMed1993

Hydrogels as an interface between bone and an implant.

The use of fully hydrated hydrogels in the body has been well established. The forces a hydrogel generates on swelling when it is placed in a constrained space were investigated with a view to providing a mechanism for fixing a prosthesis in the intramedullary cavity. A cross-linked poly(2-hydroxyethyl methacrylate) [p(HEMA)] hydrogel was investigated as a potential material. In vitro mechanical tests were carried out to determine the stresses generated in the p(HEMA) when it was placed in water and not allowed to swell. Pull out loads of up to 375 N indicated that the system could be used successfully in vivo. Consequently, the material was placed intraosseously at two sites in a rabbit animal model, in the mid-shaft (diaphysis) and the lower end (metaphysis) of the femur. Histological examination showed there was no adverse bone response; bone was growing from the endosteal surface up to and into the hydrogel in the diaphyseal implants and surrounded the hydrogel in the metaphysis. As a result of the shape and size variations in the rabbit femur, in vivo mechanical tests were found to give lower values than those obtained in vitro.

Animals↗
PubMed1990

Metabolic activity in the calcified zone of cartilage: observations on tetracycline labelled articular cartilage in human osteoarthritic hips.

The tidemark is a metabolically active zone in the calcified layer of the cartilage in which it is possible to show that there is calcifying activity even over a short period of time using a tetracycline labelling technique. The tidemark slowly advances in the direction of the non-calcified cartilage and analysis of double-tetracycline labelled cartilage shows that this is not an appositional phenomenon like that occurring in bone, but that, where present, several tidemarks can be labelled at the same time. Each tidemark may therefore be metabolically active and it is not just the tidemark adjacent to hyaline cartilage which incorporates calcium.

Bone Development↗