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This sourcebook update describes a variation of a previous sourcebook experiment that used isolated extensor digitorum longus muscle from mouse to teach skeletal muscle properties (Head SI, Arber MS. Adv Physiol Educ 37: 405–414, 2013). Gastrocnemius-sciatic nerve preparation in an anaesthetized rat was developed and muscle contractions were recorded in a computerized data acquisition system using an isometric force transducer. Teachers and students in physiology or biology can use this preparation to demonstrate skeletal muscle properties like simple muscle twitch, quantal summation, wave summation, superposition, incomplete tetanus, complete tetanus, treppe, fatigue, and length-tension relationship.

Cleistanthus collinus leaf extracts are consumed for suicidal purposes in southern India. The boiled decoction is known to be more toxic than the fresh leaf juice. Although several compounds have been isolated and their toxicity tested, controversy remains as to which compounds are responsible for the high level of toxicity of C. collinus. We report herein that cleistanthoside A is the major toxin in the boiled aqueous extract of fresh leaves and causes death in rats in small doses. The toxicity of the boiled extract prepared in the manner described can be attributed entirely to cleistanthoside A. Cleistanthin A could also be isolated from the boiled extract, albeit in trace amounts. As hypotension not responding to vasoconstrictors is the cause of death in patients who have consumed the boiled extract, effects of cleistanthoside A on the determinants of blood pressure, namely, force of cardiac contraction and vascular resistance, were tested in isolated organ experiments. Cleistanthoside A has a direct vasoconstrictor effect; however, it inhibits ventricular contractility. Therefore, the notion that the shock in C. collinus poisoning is of vascular origin must be considered carefully, and the possibility of cardiogenic shock must be studied. We present the crystal structure of cleistanthin A and show the potency of fast NMR methods (NOAH4-BSCN-NUS) in the full spectral assignment of cleistanthoside A as a real-world sample of a natural product. We also compare the results of the NOAH4-BSCN-NUS NMR experiments with conventional NMR methods.

Objectives Accurate diagnosis of osteoarthritis (OA) is the first important step in ensuring appropriate management of the disease. A multitude of tests involving assessment of biomarkers help in assessment of severity and grading of osteoarthritic damage. However, most tests are time consuming and are limited by the paucity in synovial fluid volume. In majority of OA effusions, calcium containing crystals are found. The aim of our study was to evaluate whether a correlation existed between the amount of calcium containing crystals present in synovial fluid and severity scoring of OA to propose a quick and inexpensive technique for disease assessment. Materials and methods Monosodium-iodoacetate was used to induce high- and low-grade knee OA in adult New Zealand white rabbits (n = 6 joint each group). At 16 weeks, synovial fluid and joints were harvested for histopathological analysis. OA grading was established based on OARSI scoring. Synovial fluid calcium crystal count was assessed by light microscopy (Alizarin red) and confirmed by Fluo-4, AM imaging and polarized microscopy. Statistical analysis was performed using unpaired Student t-test and Pearson correlation. Results and conclusion The clumps counted in low-grade OA were significantly lower than high-grade OA, in addition to showing a positive correlation (coefficient: 0.65; P=0.021) between calcium crystal count and the grade of OA created. Fluo-4, AM staining, and polarized microscopy were indicative of calcium pyrophosphate dihydrate crystals. This is the first study to suggest that Alizarin red could serve as an effective and rapid, bed-side method for screening and assessing disease progression.

A good understanding of red cell indexes can aid medical students in a considerable manner, serving as a basis to unravel both concepts in red cell physiology and abnormalities associated with the same. In this study, we tried to assess whether an interactive animation was helpful in improving student comprehension and understanding of red cell indexes compared with conventional classroom teaching. Eighty-eight first-year MBBS students participated, of which 44 were assigned to group A and 44 were assigned to group B after randomization. After further creation of smaller groups, students were provided with 45 min to revise red cell indexes, after which they were required to complete a multimodal questionnaire. Group A subgroups used written material for revision, whereas group B subgroups had access to an interactive animation. After completion of the questionnaire, group A students also used the animation after which feedback was collected from all students. Efficacy of the animation to improve learning and retention was demonstrated, as group B students scored significantly higher than group A students on the questionnaire ( P = 0.0003). A clear majority of the students agreed/strongly agreed that the animation was easy to operate, conveyed important concepts efficiently, and improved their knowledge of related clinical aspects as well. From the results and feedback, we found that the animation was a simple, well-received model, which, by significantly improving student performance, corroborated our hypothesis that inclusion of interactive animation into student curriculum can advance their academic attainment, compared with didactic teaching alone.