The goal of this review is to present a comprehensive survey of the many intriguing facets of creatine (Cr) and creatinine metabolism, encompassing the pathways and regulation of Cr biosynthesis an...

http://www.afboard.com/library/creatinemetabolism.pdf

Creatine and Creatinine Metabolism

What is the cause of the ageing atrophy? Total number, size and proportion of different fiber types studied in whole vastus lateralis muscle from 15- to 83-year-old men

Nonsteroidal anti-inflammatory drugs (NSAIDs) represent one of the most highly utilized classes of pharmaceutical agents in medicine. All NSAIDs act through inhibiting prostaglandin synthesis, a catalytic activity possessed by two distinct cyclooxygenase (COX) isozymes encoded by separate genes. The discovery of COX-2 launched a new era in NSAID pharmacology, resulting in the synthesis, marketing, and widespread use of COX-2 selective drugs. These pharmaceutical agents have quickly become established as important therapeutic medications with potentially fewer side effects than traditional NSAIDs. Additionally, characterization of the two COX isozymes is allowing the discrimination of the roles each play in physiological processes such as homeostatic maintenance of the gastrointestinal tract, renal function, blood clotting, embryonic implantation, parturition, pain, and fever. Of particular importance has been the investigation of COX-1 and -2 isozymic functions in cancer, dysregulation of inflammation, and Alzheimer's disease. More recently, additional heterogeneity in COX-related proteins has been described, with the finding of variants of COX-1 and COX-2 enzymes. These variants may function in tissue-specific physiological and pathophysiological processes and may represent important new targets for drug therapy.

Cyclooxygenase Isozymes: The Biology of Prostaglandin Synthesis and Inhibition

Food systems need to produce enough of the essential trace element Se to provide regular adult intakes of at least 40 microg/d to support the maximal expression of the Se enzymes, and perhaps as much as 300 microg/d to reduce risks of cancer. Deprivation of Se is associated with impairments in antioxidant protection, redox regulation and energy production as consequences of suboptimal expression of one or more of the Se-containing enzymes. These impairments may not cause deficiency signs in the classical sense, but instead contribute to health problems caused by physiological and environmental oxidative stresses and infections. At the same time, supranutritional intakes of Se, i.e. intakes greater than those required for selenocysteine enzyme expression, appear to reduce cancer risk. The lower, nutritional, level is greater than the typical intakes of many people in several parts of the world, and few populations have intakes approaching the latter, supranutritional, level. Accordingly, low Se status is likely to contribute to morbidity and mortality due to infectious as well as chronic diseases, and increasing Se intakes in all parts of the world can be expected to reduce cancer rates.

/pdf/selenium-in-global-food-systems-23a5koo10v.pdf

Selenium in global food systems.

Mammalian skeletal muscle shows an enormous variability in its functional features such as rate of force production, resistance to fatigue, and energy metabolism, with a wide spectrum from slow aer...

Calcium Ion in Skeletal Muscle: Its Crucial Role for Muscle Function, Plasticity, and Disease

Biopsies for histochemical and ultrastructural studies were taken from the M. vastus lateralis of 45 healthy sedentary men and women aged 65--89 years. With increasing age the histochemical reactions reveal changes inthe fibre type distribution characterized by a decrease in the percentage and predominant atrophy of type II fibres. The most frequent changes in the oldest subjects are: targetoid fibres, type I fibre predominance, and type grouping phenomena; expressions of denervation. Myopathic alterations are observed unusually. Electron microscopic findings are characterized by myofibrillar disorder, streaming of Z line and rod formation, and dilatation and increase of sarcoplasmic reticulum. As the age increases, the fibres become richer in intracellular lipid droplets and lysosomes. Intramuscular microcirculatory alterations, consisting of arteriolosclerotic changes and increase in width of the capillary basement membrane, are also observed and discussed.

Histochemical and ultrastructural aspects of m. vastus lateralis in sedentary old people (age 65--89 years).

Anterior tibial muscle biopsies of the hemiplegic side of 16 patients with a cerebrovascular accident in the middle cerebral artery region were analyzed qualitatively and quantitatively by enzyme histochemistry and electron microscopy. Patients grouped according to the time lapsed as from the occurrence of the accident (1-17 months) demonstrated a progressive decrease in the fiber diameter and changes in fiber type distribution with predominant type II atrophy and type I predominance. Nuclear internalization, myopathic alterations, and perifascicular fatty infiltrations were observed constantly. In the affected fibers the ultrastructural findings were myofibrillar alterations with the formation of rods and cytoplasmic bodies. There was accumulation of lipofuscin, glycogen, and lipid droplets. Microvascular changes were observed frequently. Biopsies from the asymptomatic legs were either normal or showed age-related muscle alterations. Correlation was noted between the clinical and functional status of the patients and the morphological aspects seen in muscle biopsies.

Hemiplegic atrophy: morphological findings in the anterior tibial muscle of patients with cerebral vascular accidents

Biopsies of the rectus femoris muscle of 22 paraplegic patients with complete acute spinal cord transection due to trauma were taken for enzyme-histochemical and electron-microscopic studies in successive stages starting from occurrence of the accident (1-17 months). Ingravescent muscular atrophy was demonstrated with a progressive decrease in the fiber diameter and changes in the fiber type distribution with predominant type II atrophy in the first stage and type I atrophy in the later stage of the cord transection. Muscular "neurogenic" changes, such as angular dark atropic fibers, targetoid fibers, and type predominance are frequently observed. Myopathic alterations are observed in a low percentage in the later stages of the lesion. The ultrastructural findings are characterized by myofibrillar alterations and by dilatation and proliferative phenomena of the sarcoplasmic reticulum and T-system. There are ingravescent accumulation of lipid, interstitial fibrosis and microcirculatory alterations. The possible mechanism of "central" muscle atrophy is reviewed and discussed with reference to the morphological findings.

Muscle fiber type morphology and distribution in paraplegic patients with traumatic cord lesion. Histochemical and ultrastructural aspects of rectus femoris muscle.

The Cycloxygenase-2 inhibitor SC58236 is neuroprotective in an in vivo model of focal ischemia in the rat.

A qualitative and quantitative analysis of M. vastus lateralis fibers from 40 male sedentary subjects, ranging in age from 30 to 89 years, was carried out by light and electron microscopy and by an automatic Interactive Image Analysis System. Biopsies for enzyme histochemical and ultrastructural studies were taken from subjects subdivided into four age groups: 30-50, 60-70, 71-80, and 81-89 years. Attention was focused on the fiber type size and distribution, the size and the amount of mitochondria, and the amount of lipid droplets. Main changes observed in the four age groups are indicative of a sequence of events within senescent skeletal muscle fibers. With increasing age the enzyme histochemical reactions reveal changes in fiber type distribution characterized by decrease in muscle fiber diameter and by type I fiber predominance. Type II fiber atrophy is consistent. Type I fiber predominance seen in older subjects could be related to a selective decrease of type II fibers with age. It also suggests a possible conversion of type II fibers to type I fibers. Lipid droplet percentage per fiber area increases, while mitochondrial size and mitochondrial percentage per fiber area decrease with age. It is possible that energy requirements decline with age and that the decrease in mitochondrial size and percentage represents a response to a reduced metabolic demand.

Roberto Scelsi

Papers

Histochemical and ultrastructural aspects of m. vastus lateralis in sedentary old people (age 65--89 years).

Hemiplegic atrophy: morphological findings in the anterior tibial muscle of patients with cerebral vascular accidents

Muscle fiber type morphology and distribution in paraplegic patients with traumatic cord lesion. Histochemical and ultrastructural aspects of rectus femoris muscle.

The Cycloxygenase-2 inhibitor SC58236 is neuroprotective in an in vivo model of focal ischemia in the rat.

Automatic morphometric analysis of skeletal muscle fibers in the aging man.