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Biomedical subjects

S P Frostick

Publications and source records attributed to S P Frostick.

At least 19 recordsLinked to original sources
PubMed2000

Estimation of body composition in muscular dystrophy by MRI and stereology.

We have applied the Cavalieri method of modern design stereology with magnetic resonance imaging for estimating the volume of whole-body muscle and fat compartments in four patients with muscular dystrophy, a patient with myopathy, five controls, an anorexic subject, and a body builder. Detailed systematic series (ie, 50) of axial MR images (T1-weighted, TR/TE 400/10 msec) were obtained throughout the whole body of each subject. The results showed that 15, 20, and 35 axial sections through the body are sufficient to secure coefficients of error (CEs) on the estimates of total muscle and fat volume of around 10%, 5%, and 3% respectively in muscular dystrophy patients and controls. The mean normalized volumes of muscle in four muscular dystrophy patients were decreased by 27% (t-test: P < 0.05), and those of total fat were increased by 12% (t-test: P > 0.05) relative to controls. The Cavalieri method provides a direct, efficient, and mathematically unbiased approach for studying human body compartments and may have application in assessing treatment efficacy in patients with muscular dystrophy. J. Magn. Reson. Imaging 2000;12:467-475.

Adipose Tissue↗
PubMed1998

Schwann cells, neurotrophic factors, and peripheral nerve regeneration.

The peripheral nervous system retains a considerable capacity for regeneration. However, functional recovery rarely returns to the preinjury level no matter how accurate the nerve repair is, and the more proximal the injury the worse the recovery. Among a variety of approaches being used to enhance peripheral nerve regeneration are the manipulation of Schwann cells and the use of neurotrophic factors. Such factors include, first, nerve growth factor (NGF) and the other recently identified members of the neurotrophin family, namely, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), neurotrophin-4/5 (NT-4/5); second, the neurokines ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF); and third, the transforming growth factors (TGFs)-beta and their distant relative, glial cell line-derived neurotrophic factor (GDNF). In this review article we focus on the roles in peripheral nerve regeneration of Schwann cells and of the neurotrophin family, CNTF and GDNF, and the relationship between these. Finally, we discuss what remains to be understood about the possible clinical use of neurotrophic factors.

Animals↗
PubMed1998

Neurotrophins, neurones and peripheral nerve regeneration.

Successful peripheral nerve regeneration requires optimal conditions both in the macro-environment and micro-environment. Many methods have been used to improve the macro-environment for the regenerating nerve. However, much less is known about the micro-environment, and in particular the complex neurochemical interactions involved. Several neurotrophic factors have been shown to play an essential trophic role in the development, maintenance and regulation of neuronal function. These include nerve growth factor (NGF) and several recently identified members of the NGF family, namely brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), neurotrophin-4/5 (NT-4/5) and neurotrophin-6 (NT-6). In this review we summarize recent studies of the effects of these neurotrophins on neurones, especially their effects on motor neurones and their axonal outgrowth. We discuss prospects for the future and point out what remains to be understood about the role of neurotrophins to enhance peripheral nerve regeneration.

Animals↗
PubMed1998

A study of the reproducibility of three different normalisation methods in intramuscular dual fine wire electromyography of the shoulder.

The purpose of this study was to determine the most appropriate method of normalisation for dual fine wire electromyography of shoulder muscles. Five healthy subjects were studied, with one muscle investigated in each subject (2 supraspinatus, 2 infraspinatus, 1 subscapularis). Three dual fine wire electrodes were inserted 1 cm apart around the recognised insertion points. Each subject performed five types of cyclic exercise on an isokinetic muscle dynamometer with an isometric maximal voluntary contraction (MVC) being performed before and after the exercise protocol. The EMG signal was normalised using each of the MVC voltage, the peak voltage and the whole-cycle mean voltage. There was a considerable difference (5-143%) between the MVC signals pre- and post-protocol, although no systematic trend was demonstrable. The overall mean between electrode variation in the normalised signal measured at the peak of the cycle ranged from 48-71% when normalised to pre-protocol MVC, but only 4-13% when normalised to the peak voltage and 9-17% using the whole-cycle mean voltage. However the pattern of activation within the movement cycle, which was preserved by normalisation using the peak or mean signal, was consistent between different electrode positions. It was concluded that the EMG signal depended on electrode position even when near the recognised insertion point, and that the MVC signal is highly variable in magnitude between electrodes and between pre- and post-protocol measurements.

Adult↗
PubMed1996

Endurance-trained and untrained skeletal muscle bioenergetics observed with magnetic resonance spectroscopy.

Resting and submaximal isometric exercise 31P magnetic resonance spectroscopy (MRS) was carried out on 7 endurance-trained males (26.0 +/- 3 yrs) and 7 sedentary males (27.0 +/- 4 yrs). Spectral analysis provided peak areas of phosphocreatine (PCr), inorganic phosphate (Pi), adenosine triphosphate (ATP), and the chemical shift of Pi relative to PCr. The ratio of PCr/Pi was moderately lower during rest (preexercise p = .13, postexercise p = .18), and significantly higher during exercise (p < .05) in the trained subjects. Intracellular pH patterns were the same for both groups; a transient alkalosis was observed at the onset of exercise with a return to resting levels after 2 min. Differences suggest improved ATP resynthesis rate in the trained subjects during exercise. Intracellular pH changes can be attributed to the utilization of hydrogen ions that accompany PCr hydrolysis during work. The findings are congruent with previous reports indicating a superior oxidative capacity in trained skeletal muscle.

Adenosine Triphosphate↗
PubMed1995

Microsurgery.

Explore the source record for details and available documents.

Clinical Protocols↗
PubMed1995

The physiological and metabolic consequences of muscle denervation.

Fundamental metabolic changes occur in muscle following damage of the nerve supply. These changes include alterations in the enzyme activities associated with oxidative phosphorylation and glycolysis, and alteration in the metabolism of cAMP, changes in the sensitivity to insulin and other alterations of the handling of glucose and probably also an alteration in the metabolism of Ca2+ possibly resulting in a metabolic myopathy. There are also changes in the turnover of acetylcholine receptors and possibly cytoskeletal proteins such as dystrophin-related protein. The biochemical changes are paralleled by similar alterations in physiological parameters such as electromyographic measurements and structural changes such as those that occur at the endplate. Similar genes to those which are active during muscle cell development may be "switched-on" following a nerve injury. The return of these parameters to normal after reinnervation is variable and may be incomplete.

Animals↗
PubMed1994

Compression neuropathy of the common peroneal nerve caused by a ganglion.

A case of compression of the common peroneal nerve caused by a ganglion herniating from the superior tibio-fibular joint is reported. MR imaging was partially helpful in making the diagnosis. The patient has made an almost complete recovery 3 months after excision of the lesion. Early diagnosis and treatment is required to ensure recovery.

Ganglia↗
PubMed1994

Pisotriquetral loose body. An unusual cause of wrist pain.

A loose body flicking in and out of the pisotriquetral joint was found to be the cause of intermittent wrist pain and locking in two patients. Appropriate X-rays gave the diagnosis and surgical removal provided a satisfactory cure.

Adult↗
PubMed1993

Heparin induced thrombosis: an important complication of heparin prophylaxis for thromboembolic disease in surgery.

Heparin induced thrombocytopenia with thrombosis, or the "white clot syndrome," is a rare but recognised complication of heparin therapy. The syndrome is idiosyncratic, immune mediated, and not dose dependent and therefore is equally likely to occur with prophylactic and therapeutic heparin dosage regimens. Despite published reports on the subject we were alarmed that many surgeons who regularly use heparin to prevent or treat thrombosis were unaware that heparin can induce thrombotic complications in susceptible patients. We present three typical case histories, a brief discussion of the condition, and some guidelines on its prevention and treatment.

Aged↗
PubMed1993

Cellular energetics of dystrophic muscle.

Cytosolic pH and phosphorus metabolite ratios in skeletal muscle were measured by 31P magnetic resonance spectroscopy in patients with Duchenne muscular dystrophy (DMD) and Becker's muscular dystrophy (BMD) and in Duchenne/Becker carriers. In resting dystrophin-deficient muscle, there was a decrease in phosphocreatine (PCr) and increase in orthophosphate (Pi) relative to ATP, and an increase in calculated free [ADP]. Phosphomonester and phosphodiester were also increased relative to ATP. These changes were largest in DMD, smaller in BMD and small or absent in carriers. Cytosolic pH was increased substantially in DMD, moderately in BMD and slightly but significantly in gastrocnemius of carriers. Raised intracellular pH thus appears to be the most characteristic abnormality in dystrophin-deficient muscle. Responses to erobic exercise were studied in the forearm muscle flexor digitorum superficialis of carriers. PCr depletion during exercise was greater than normal but the fall in pH was disproportionately small, resulting in increased [ADP]. This is likely to result either from reduced anaerobic glycogenolysis to lactic acid or from increased proton efflux (as is seen in mitochondrial myopathy). Detailed analysis suggests: (1) at the start of exercise, calculated lactic acid production was increased, as was the rate of PCr depletion, suggesting that there was no absolute defect of glycogenolysis. (2) At the start of recovery, calculated proton efflux was not increased, although as the pH at the end of exercise was higher than in controls and proton efflux is normally pH-dependent, an up-regulation of proton efflux cannot be excluded. (3) Recovery of PCr, Pi and ADP after exercise were not impaired, suggesting that mitochondrial function is normal.

Adenosine Diphosphate↗
PubMed1992

Human muscle cell denervation: the results of a 31-phosphorus magnetic resonance spectroscopy study.

The results presented here demonstrate that there is a major abnormality of high and low energy phosphate metabolism in muscle following peripheral nerve damage. Using 31-phosphorus magnetic resonance spectroscopy the changes in phosphocreatine, adenosine triphosphate, inorganic phosphate and metabolites of membrane metabolism could be observed in vivo in human subjects. The data indicate that there may be a metabolic myopathy in the muscle cells after nerve injury. Further, the metabolic changes did not always return to the control level, indicating a persistence of the abnormality. This failure of the metabolic function of the cells may be important in determining the ultimate outcome of peripheral nerve surgery.

Adenosine Triphosphatases↗
PubMed1991

Denervation of the rabbit hind limb studied by 31-phosphorus magnetic resonance spectroscopy.

An animal model of muscle denervation was examined by 31P. magnetic resonance spectroscopy. The experiments demonstrated that there is a significant alteration in high and low energy phosphate metabolites in rabbit muscle after nerve section. The data show that there is an early change in the metabolites which appears to plateau at about six weeks. High resolution spectra of muscle cell extracts demonstrate qualitative alterations in the phosphate resonances found in the phosphodiester and phosphomonoester regions of the spectra. There would seem to be a time-related alteration in these components.

Adenosine Triphosphate↗
PubMed1991

One-stage bilateral thoracoscapular fusion using allografts. A case report.

A 28-year-old woman with fascioscapulohumeral muscular dystrophy was treated with a one-stage bilateral scapulothoracic fusion. At operation, cortical allografts with screw fixation for anchorage were used, supplemented with autologous cancellous bone. A proper balance and symmetry of the shoulder girdle can be restored more easily when fusion is performed bilaterally at the same time.

Adult↗
PubMed1990

Hypophosphataemia after renal transplantation: relationship to immunosuppressive drug therapy and effects on muscle detected by 31P nuclear magnetic resonance spectroscopy.

Plasma phosphate values were examined in 72 renal transplant patients in a randomised trial of immunosuppression with azathioprine and prednisolone versus cyclosporin alone. From 21 to 77 days after transplantation, in patients with plasma creatinine concentrations of 75-150 mumol/l, mean plasma phosphate was 0.98 (SEM 0.04) mmol/l in cyclosporin-treated patients, compared with 0.65 (SEM 0.12) mmol/l in cyclosporin-treated patients receiving pulse methylprednisolone for rejection (P less than 0.003), and 0.68 (SEM 0.02) mmol/l in patients treated with azathioprine and prednisolone (P less than 0.001). There was no difference between the mean plasma creatinine of these groups of patients. A preliminary study by nuclear magnetic resonance spectroscopy of four patients with asymptomatic chronic hypophosphataemia showed reduced concentrations of intracellular phosphate in resting muscle, and further abnormalities developed on exercise. Thus, exogenous steroid administration is a major contributing factor of hypophosphataemia in the early post-transplant period. In addition chronic hypophosphataemia may be associated with reduced intracellular inorganic phosphate concentrations detectable by nuclear magnetic resonance spectroscopy, although these changes are not apparently associated with any clinical symptoms.

Azathioprine↗