Studies on the peripheral blood and the in vitro response of peripheral blood lymphocytes to common mitogens in Macaca speciosa

In a longitudinal study on 13 adult female stumptailed macaques, Macaca speciosa, peripheral blood samples were analyzed hematologically and the in vitro response of the lymphocytes to the common mitogens concanavalin A, phytohemagglutinin and pokeweed mitogen were investigated. The results showed that the total leukocyte and differential counts in each animal remained quite stable throughout the 3-month experiment. The responses in culture to the mitogens showed that there were differences in the stimulation obtained by each mitogen and that the animals may be placed into high, medium and low groups based on differences in their level of response.     

Pathology of acute myocardial infarction with particular reference to occlusive coronary thrombi

Analysis of the pathological findings in 500 cases of fatal acute myocardial infarction showed that in 469 this was localized to one transmural area of the left ventricle; in 31 there was diffuse subendocardial necrosis. In the former occlusive coronary thrombus was found in the related artery in 95 per cent of cases. Variation in the percentage of occlusions found was noted between different prosectors and when coronary artery calcification was present. Only 4 of the 31 patients with subendocardial necrosis had recent occlusion; triple vessel disease was common in this group suggesting general failure of coronary perfusion. It is essential in necropsy studies of the relation of coronary thrombosis to myocardial infarction to be sure that muscle necrosis is present, to distinguish the two forms of myocardial necrosis, and to employ a meticulous dissection technique with decalcification of the arteries when necessary.     

The systemic arterial pattern of the guinea pig: the pelvis and pelvic limb

The changes of heart rate in response to i.v. administration of methylatropine (0.5 mg/kg) and/or propranolol (2 mg/Kg) or practolol (2.5 mg/Kg) were studied in conscious trained dogs. Cholinergic blockade alone or combined blockade of sympathetic and parasympathetic effector systems resulted in cardiac acceleration. Conversely, beta-adrenoceptor antagonism with either propranolol or practolol reduced heart rate. The data were analysed by means of a new method, whereby the heart (HRN) of the dog is considered to be the product of the intrinsic heart rate (HR0) and 3 further factors: HRN-HR0 times S times V times W (Multiplicative model). 2 of these factors represent the tonic sympathetic (S) and parasympathetic (V) influences, whereas the third (W) represents the sympathetic-parasympathetic interaction. This type of analysis reveals that W was approximately 1, i.e., the sympathetic-parasympathetic interaction did not play any significant role in determining the heart rate of conscious resting dogs (HRN = HRO-S-V-W = HRO-S-V). The change of heart rate due to the action of parasympathetic system (-53% of the intrinsic heart rate) was more important than the change caused by the action of the sympathetic system (26% of the intrinsic heart rate).     

Crystal structure of TNF-alpha mutant R31D with greater affinity for receptor R1 compared with R2

Crystal structures have been determined of recombinant human tumor necrosis factor-alpha (TNF-alpha) and its R31D mutant that preferentially binds to TNF receptor R1 with more than seven times the relative affinity of binding to receptor R2. Crystals of the wild-type TNF were of space group P4(1)2(1)2 and had unit cell dimensions of a = b = 94.7 and c = 117.4 A. Refinement of the structure gave an R-factor of 22.3% at 2.5 A resolution. The crystals of TNF R31D mutant diffracted to 2.3 A resolution, and were of identical space group to the wild type with unit cell dimensions of a = b = 95.4 and c = 116.2 A, and the structure was refined to an R-factor of 21.8%. The trimer structures of the wild-type and mutant TNF were similar with a root mean square (r.m.s.) deviation of 0.56 A for Calpha atoms; however, the subunits within each trimer were more variable with an average r.m.s. deviation of 1.00 A on Calpha atoms for pairwise comparison of subunits. Model complexes of TNF with receptors R1 and R2 have been used to predict TNF-receptor interactions. Arg31 in all three subunits of wild-type TNF is predicted to form an ionic interaction with the equivalent glutamic acid in both receptors R1 and R2. Asp31 of the TNF R31D mutant is predicted to interact differently with the two receptors. The side chain of Asp31 in two subunits of the TNF mutant is predicted to form hydrogen bond interactions with Ser59 or Cys70 of R1, while it has no predicted interactions with R2. The loss of three strong ionic interactions of Arg31 and the electrostatic repulsion of Asp31 with Glu in the receptors is consistent with the reduced binding of the R31D mutant to both receptors relative to wild-type TNF. The replacement of these ionic interactions by two weaker hydrogen bond interactions between Asp31 of the R31D mutant and R1, compared with no interactions with R2, is in agreement with the observed preferential binding of the R31D mutant to R1 over R2. Analysis of the structure and function of receptor-discriminating mutants of TNF will help understand the biological role of TNF and facilitate its use as an antitumor agent.