A comparative analysis of kinetic models of erythrocyte glycolysis.

Since the 1970s, with Heinrich as a pioneer in the field, numerous kinetic models of erythrocyte glycolysis have been constructed. A functional comparison of eight of these models indicates that the production of ATP and GSH in the red blood cell is largely controlled by the demand reactions. The rate characteristics for the supply and demand blocks indicate a good homeostatic control of ATP and GSH concentrations at different work loads for the pathway, while the production rates of ATP and GSH can be adjusted as needed by the demand reactions.

Middle ear tuberculosis--a series of 24 patients.

A study of 24 cases (25 ears) of tuberculous otitis media is revealed. Characteristic findings of the disease e.g. painless ottorhea and multiple perforations of the tympanic membrane, are not considered consistent with our findings of the clinical features of the pathology. Severe conductive hearing loss, abundant pale granulations and an eroded maleus handle consistently occurs in the pathology and in our opinion are more significant clinical features of the disease. As mixed infections are often present, histological examination of the granulation tissue from the middle ear and mastoid is the best diagnostic procedure. Treatment with anti-tuberculous therapy combined with surgery is shown to give good results.

The influence of dietary crude protein intake on bone and mineral metabolism in sheep.

Increased dietary protein consumption is thought to cause calciuresis, a negative calcium balance and increased bone loss that may result in skeletal deformities and fracture. To explore this hypothesis, 40 approximately 100-day-old meat-type Merino ram lambs were fed, for 6 months, diets with an increasing crude protein (CP) content (114, 142, 171 and 190 g/kg DM) but approximately on an iso-nutrient basis with regard to metabolisable energy, calcium and phosphorus. Increased protein consumption modestly (NS) enhanced calciuresis and resulted in significant (P < or = 0.01) limb skewness. This could not, however, be ascribed to osteopaenic bones, and compared with animals consuming lower protein rations, the bone mineral density (BMD) and vertebral trabecular bone volume of animals fed high protein diets were significantly increased: the BMD of thoracic vertebrae was positively related to the CP intake (r = 0.62; P < or = 0.001). In animals consuming higher protein diets, skeletal radiology and quantitative bone histology revealed no evidence of increased bone turnover as would be expected in animals that are in negative calcium balance. No relationship existed between limb skewness and the growth rate of lambs. However, the ratio of Ca:P in the forelimb (r = -0.98), vertebrae (r = -0.72) and rib (r = -0.42) was found to be inversely correlated with increased protein intake and resulted from an increase in the phosphorus content of bone, while the amount of bone calcium was unaffected. We conclude that qualitative micro-architectural abnormalities, and not mere bone loss, may underlie the skeletal deformities induced by increased protein consumption in sheep.

Summation theorems for flux and concentration control coefficients of dynamic systems.

Metabolic control analysis (MCA) was developed to quantify how system variables are affected by parameter variations in a system. In addition, MCA can express the global properties of a system in terms of the individual catalytic steps, using connectivity and summation theorems to link the control coefficients to the elasticity coefficients. MCA was originally developed for steady-state analysis and not all summation theorems have been derived for dynamic systems. A method to determine time-dependent flux and concentration control coefficients for dynamic systems by expressing the time domain as a function of percentage progression through any arbitrary fixed interval of time is reported. Time-dependent flux and concentration control coefficients of dynamic systems, provided that they are evaluated in this novel way, obey the same summation theorems as steady-state flux and concentration control coefficients, respectively.