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Reflex vasoconstrictive responses are commonly used to assess sympathetic nerve function of the extremities. A regularly used reflex trigger is deep and rapid inspiration. However, little is known about the relationship between respiratory effort and the magnitude of the resultant vasoconstrictor response. This study investigates the association of inspiratory flow rate and volume to the level of vasoconstrictor reflexes in the 4th digit tip skin and the ulnar artery in 12 healthy volunteers (age range 21-65, mean 38.1 years). The effects of Peak Inspiratory Flow (PIF) and Forced Inspiratory Vital Capacity (FIVC) on blood flow were measured at three levels of respiratory effort: low (PIF < 1.0 l/min; FIVC < 1.0 l), medium (PIF = 1.0-1.5 l/min; FIVC = 1.0-1.5 l), and high (PIF > 1.5 l/min; FIVC > 1.5 l) at two separate occasions. Ulnar vasoconstrictor responses showed good correlation with all levels of respiratory effort. Skin digit tip responses showed good correlation at medium and high levels but not at low respiratory effort. Repeatability of both tests was good. Correlation of inspiratory flow rate to vasoconstriction was consistently better than with inspiratory volume. Both digit tip and ulnar vasoconstrictor responses were maximal with greatest respiratory effort.

A total of 100 post-mortems were done on patients clinically diagnosed as dengue haemorrhagic fever from Rangoon Children's Hospital. Histopathological changes in bone marrow, thymus, spleen, lymph nodes and other associated tissues of the immune system were analysed and correlated with the clinical picture and serology results. The major changes in cases with a positive serology result for secondary dengue infection consist of hypoplasia of the bone marrow, acute atrophy and wasting of the thymus, atrophy and depletion of cells in the periarterial lymphatic sheaths of the spleen and the paracortical areas of the lymph nodes. The tissues affected are the thymus-dependent areas of the spleen and lymph nodes, and the thymus itself. Thymus-independent areas of the secondary lymphatic tissues are also affected but to a lesser extent. The pathological observations suggest that immunodepression may be an integral part of the pathophysiology of dengue haemorrhagic fever.

The effects of Russell's viper venom (RVV) on blood coagulation, platelts and fibrinolysis were studied in vivo and in vitro in rabbits and dogs as experimental subjects. RVV was shown to be a strong coagulant, and at the time of manifestation of bleeding due to consumption coagulopathy, the most striking hemostatic abnormalities were fall of fibrinogen level, reduction in platelet count, delayed ADP aggregation of platelets, increased fibrinolytic activity and presence of fibrin degradation products. These findings showed that RVV interfered with blood coagulation, caused abnormalities of platelet function and also activated the fibrinolytic enzyme system.