Anthropometric Studies of Human Subjects Susceptible to Malignant Hyperpyrexia

Height, weight, and skinfold thickness were measured on 82 patients prior to muscle biopsy which was performed to determine their susceptibility to malignant hyperpyrexia. Percentage body fat was calculated from the skinfold measurements. Using AP photographs six coronal diameters of the left thigh. equally spaced between the lower border of the patella and the perineum, were measured on another group of 90 patients referred for biopsy. The subjects were then divided into those who were susceptible to malignant hyperpyrexia (MHS) and those who were normal and acted as controls. Each group was separated into males and females. There was no significant difference in age between the MHS and the control groups. There was no difference between MHS and controls in height or weight but the percentage body fat in the MHS males was significantly lower than in the controls (P<0.02). The upper three thigh diameters in the MHS females were significantly greater than in the control group (P<0.05). There appears to be a difference in the leanness/fatness relationship and in the development of the thigh in MHS subjects compared with controls, but these differences are subtle and appear to vary with sex.     

Haem in the gut. I. Fate of haemoproteins and the absorption of haem

Haem (FeII-protoporphyrin-IX) is presented to the gut lumen as haemoproteins derived from exogenous dietary) and endogenous (mucosal cell desquamation and bleeding) sources. Haemoproteins such as haemoglobin, myoglobin and catalase undergo hydrolysis by luminal proteases to release the haem. Released haem is maintained in a soluble form in the gut lumen by the products of haemoprotein digestion. Chelators of elemental iron do not bind haem-iron and so haem-iron is better absorbed than elemental iron. Haem-iron does not exchange with luminal elemental iron. Mucosal uptake of haem is limited. Less than 10% binds to the brush border of the villus cell. Although the mechanisms by which haem binds to the brush border and is transported to the intracellular environment are poorly understood, it is known that some haem is transferred to secondary lysosomes where the porphyrin ring is split to release iron and form bilirubin. Depending upon the composition of the diet, the iron released from haem within the villus cell can be the major physiological source of iron. In iron-deficiency in humans, absorption of haem-iron can increase threefold whereas absorption of elemental-iron can increase tenfold. These observations indicate that haem-iron and elemental-iron are absorbed via different mechanisms which are subject to different regulation. For haem-iron to be absorbed, the haem itself must be taken up by the mucosa.     

Versatile frequency domain fitting using time domain models and prior knowledge

An iterative nonlinear least-squares fitting algorithm in the frequency domain using time domain models for quantification of complex frequency domain MR spectra is presented. The algorithm allows incorporation of prior knowledge and has both the advantage of time-domain fitting with respect to handling the problem of missing data points and truncated data sets and of frequency-domain fitting with respect to multiple frequency-selective fitting. The described algorithm can handle, in addition to Lorentzian and Gaussian line-shapes, Voigt and nonanalytic lineshapes. The program allows the user the design of his own fitting strategy to optimize the probability of reaching the global least-squares minimum. The application of the fitting program is illustrated with examples from in vivo ¹H– ³¹P-, and ¹³C-MR spectroscopy.