Measuring perfusion and bioenergetics simultaneously in mouse skeletal muscle: a multiparametric functional-NMR approach.

A totally noninvasive set-up was developed for comprehensive NMR evaluation of mouse skeletal muscle function in vivo. Dynamic pulsed arterial spin labeling-NMRI perfusion and blood oxygenation level-dependent (BOLD) signal measurements were interleaved with (31)P NMRS to measure both vascular response and oxidative capacities during stimulated exercise and subsequent recovery. Force output was recorded with a dedicated ergometer. Twelve exercise bouts were performed. The perfusion, BOLD signal, pH and force-time integral were obtained from mouse legs for each exercise. All reached a steady state after the second exercise, justifying the pointwise summation of the last 10 exercises to compensate for the limited (31)P signal. In this way, a high temporal resolution of 2.5 s was achieved to provide a time constant for phosphocreatine (PCr) recovery (τ(PCr)). The higher signal-to-noise ratio improved the precision of τ(PCr) measurement [coefficient of variation (CV) = 16.5% vs CV = 49.2% for a single exercise at a resolution of 30 s]. Inter-animal summation confirmed that τ(PCr) was stable at steady state, but shorter (89.3 ± 8.6 s) than after the first exercise (148 s, p < 0.05). This novel experimental approach provides an assessment of muscle vascular response simultaneously to energetic function in vivo. Its pertinence was illustrated by observing the establishment of a metabolic steady state. This comprehensive tool offers new perspectives for the study of muscle pathology in mice models.

Functional assessment of skeletal muscle in intact mice lacking myostatin by concurrent NMR imaging and spectroscopy.

Inhibiting myostatin (mstn) causes spectacular increase in muscle mass, spurring research for therapeutic approaches against neuromuscular disorders. Yet, possible functional deterioration and compromised force production have been reported in isolated muscle of null mstn(-/-) mice. We analyzed vascular and metabolic response to repeated electro-stimulated exercise in vivo in mstn(-/-) mice compared with FVB wild-type controls (WT), using interleaved multi-parametric functional nuclear magnetic resonance (NMR) imaging and spectroscopy. At steady-state exercise, specific force of plantar flexion, phosphocreatine consumption measured by phosphorus spectroscopy and maximum perfusion measured by arterial spin-labeled (ASL) NMR imaging were identical in both groups. After exercise, phosphorus spectroscopy revealed reduced oxidative mitochondrial capacity in mstn(-/-), whereas early recovery perfusion was identical and oxygen extraction, estimated from the blood oxygen level-dependent (BOLD) contrast, was decreased when compared with WT. Hyperemia was prolonged, indicating specific regulation of the perfusional response in mstn(-/-) mice. Histology showed an increased proportion of type IIb fibers in hypertrophied muscles, but the distribution of capillary contacts per fiber between oxidative and glycolytic fibers was unaltered in mstn(-/-) compared with WT. These integrated results formed coherent evidence of a congruous, non-pathologic shift toward a more glycolytic metabolism in this model of mstn(-/-).

Aplastic crisis associated with parvovirus B19 in an adult with hereditary spherocytosis.

Parvovirus B19 is usually associated with an acute, self-limited disease in children. In patients with a congenital hemolytic anemia, infection with this virus can cause an aplastic crisis. We describe such a crisis in an adult with asymptomatic hereditary spherocytosis. The association between acute red blood cell aplasia and infection with parvovirus B19 is well described in patients with hereditary hemolytic anemia, particularly sickle cell anemia. This association has also been described, although less frequently, in patients with other inherited hemolytic diseases, such as hereditary spherocytosis. In children, human parvovirus B19 causes an acute self-limited illness known as erythema infectiosum (fifth disease). In immunocompromised individuals, chronic infections can occur and cause a severe, persistent anemia. In pregnant women, infection can, but usually does not, lead to fetal infection. An infected fetus can have severe anemia, congestive heart failure, generalized edema (fetal hydrops) and even death. Most cases of aplastic crises associated with parvovirus B19 in patients with hereditary spherocytosis have been reported in children and adolescents. In this paper we describe an aplastic crisis in a 28 year old man with asymptomatic hereditary spherocytosis.

[Unusual cause of digestive hemorrhage in chronic hemodialysis patients: splenic aneurysm with arteriovenous fistula]. / Une cause exceptionnelle d'hémorragies digestives chez l'hémodialysé chronique: l'anévrysme splénique, avec communication artério-veineuse.

A 45 years old woman, hemodialysed since 1981, with an history of Staphylococcal septicemia in may 1983, is admitted in emergency room in may 1984 for massive gastro intestinal bleeding. After oesogastro fibroscopy suspecting duodenal ulcer, because continuous and recurrent bleeding, a laparotomy find only symptoms of portal hypertension (ascites, venous dilatation on abdominal oesophagus and stomach). The ligation of this venous dilatations stop temporarily the gastro intestinal bleeding. But recurrence of this bleeding conduct to a celiac angiography discovering a splenic aneurysm with arterio venous fistula. The surgical treatment of this aneurysm can stop the gastro intestinal bleeding. Histopathologic observation of this aneurysm can suspect an infectious origin.

[Seroanthropological studies of albino and melanoderm Bamiléké populations (Cameroon). ABO and Rhesus erythrocyte groups, hemoglobin S and taste sensitivity to phenylthiocarbamide]. / Etudes séroanthropologiques des populations albinos et mélanodermes bamilékés (Cameroun). Groupes érythrocytaires ABO et Rhésus, hémoglobine S et sensibilité gustative à la phénylthiocarbamide.

Human oculocutaneous albinism is a recessive autosomic hereditary disease with a prevalence of 1/8,500 in bamileke tribe (Cameroon). ABO and Rhesus red blood cell group repartition, presence of hemoglobin S, taste sensitivity for phenylthiocarbamid in a group of 100 albino bamileke subjects were compared with these of 100 black bamileke subjects. There is no significant difference for these genetic markers mentionned above between albino and black bamileke subjects.