Renal artery stenosis: evaluation with intravenous digital subtraction angiography

The ability of diagnostic intravenous digital subtraction angiography (IVDSA) to demonstrate the degree of renal artery stenosis was compared with that of intraarterial angiography in 45 patients with 92 arteries. Stenotic lesions on both IVDSA and intraarterial studies were classified as normal (0% stenosis), minor (less than 50%), low grade (50%-80%), and high grade (80%-99%). There was agreement about the degree of stenosis in 90% of the cases. IVDSA grading was correct in 94% of atheromatous lesions and in 56% of the fibromuscular dysplastic lesions. In the high-grade atheromatous lesions, the degree of stenosis was slightly overestimated on IVDSA studies in 22.5% of the cases. In fibromuscular dysplasia, stenosis was underestimated in 33% of the cases.     

Early mechanical stimulation only permits timely bone healing in sheep

Bone fracture healing is sensitive to the fixation stability. However, it is unclear which phases of healing are mechano‐sensitive and if mechanical stimulation is required throughout repair. In this study, a novel bone defect model, which isolates an experimental fracture from functional loading, was applied in sheep to investigate if stimulation limited to the early proliferative phase is sufficient for bone healing. An active fixator controlled motion in the fracture. Animals of the control group were unstimulated. In the physiological‐like group, 1 mm axial compressive movements were applied between day 5 and 21, thereafter the movements were decreased in weekly increments and stopped after 6 weeks. In the early stimulatory group, the movements were stopped after 3 weeks. The experimental fractures were evaluated with mechanical and micro‐computed tomography methods after 9 weeks healing. The callus strength of the stimulated fractures (physiological‐like and early stimulatory) was greater than the unstimulated control group. The control group was characterized by minimal external callus formation and a lack of bone bridging at 9 weeks. In contrast, the stimulated groups exhibited advanced healing with solid bone formation across the defect. This was confirmed quantitatively by a lower bone volume in the control group compared to the stimulated groups.The novel experimental model permits the application of a well‐defined load history to an experimental bone fracture. The poor healing observed in the control group is consistent with under‐stimulation. This study has shown early mechanical stimulation only is sufficient for a timely healing outcome. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1790–1796, 2018.

     

Molecular Changes in White Matter Adjacent to an Active Demyelinating Lesion in Early Multiple Sclerosis

A stereotactic biopsy of a 17-year-old woman revealed an active inflammatory demyelinating lesion compatible with pattern III multiple sclerosis (MS) according to Lucchinetti et al . The biopsy included a white matter region distant from the active inflammatory demyelinating lesion with abnormal MRI signal, lacking histopathological signs of demyelination and/or oligodendrocyte apoptosis. Expression analysis of this area revealed a strong up-regulation of neuronal nitric oxide synthase (nNOS). Furthermore, detection of nitrotyrosine provided evidence for reactive nitrogen species (RNS)-mediated damage to oligodendrocytes. Concomitantly, genes involved in neuroprotection against oxidative stress such as heme oxygenase 1 were up-regulated. Even though a single case report, this study shows earliest molecular changes in white matter surrounding an actively demyelinating lesion during the first manifestation of MS, pointing toward a more widespread pathological process. Therapeutic targeting of the identified mechanisms of tissue injury might be crucial to prevent further lesion formation or secondary tissue damage.     

The highest battlefield of the world : Medical problems and solutions

The Indian Armed Forces Medical Services has been engaged in providing medical to the soldiers serving on Siachen Glacier for the last 25 years. This paper attempts to highlight the medical problems faced by troops on the world's highest battlefield as perceived by a medical officer located on the forward most medical echelon on Siachen Glacier. The medical problems on the glacier include high altitude pulmonary oedema, acute mountain sickness, frost bite chilblains, hypothermia, snow blindness, injury non enemy action due to avalanches, crevasses and fires, carbon monoxide poisoning and problems in disposal of nightsoil. A large number of problems are taken care of by following a well documented acclimatisation drill. However under such conditions providing medical support is a difficult task and requires innovations and improvisations entailing a high degree of mental mobility on the part of medical commanders and the Regimental Medical Officers located on the forward posts.