Allometric scaling of isokinetic peak torque: the Nebraska Wrestling Study

Allometric scaling has been used increasingly in the exercise sciences to control statistically for body size differences in physical performance variables. The purpose of this study was to use multivariate allometric scaling to examine the influence of fat-free mass (FFM) on age-related differences in strength in young club (8-13 years) and high-school (14-18 years) wrestlers. The dependent variables were log-transformed values of isokinetic peak torque for leg extension and flexion at 0.52, 3.14, and 5.24 rad x s(-1)(30, 180, and 300 x s(-1)). The independent variables used in the multiple regression analyses were log-transformed values for FFM, age, and the FFM versus age interaction. The resulting regression equations were of the form: log Y = log a + b1 log X1 + b2 log X2 + bn log Xn. The initial multiple regression analyses showed significant interaction effects (P < 0.05) for all dependent variables, therefore separate regression analyses were performed for the younger and older groups of wrestlers. The results indicate that for the younger wrestlers there were increases in isokinetic peak torque at all velocities across age after controlling for FFM. The FFM scaling exponents ranged from 0.94 to 1.31. All exponents included 1.0 in the 95% confidence interval, except for extension at 3.14 rad x s(-1). For the high-school wrestlers, both FFM and age were significant for the extension data, but only FFM was significant for the flexion data. All FFM exponents included 1.0 in the 95% confidence interval. These results indicate that the relationship between FFM and peak torque differed across age. In addition, with the exception of the flexion data for the high-school wrestlers, within each group increases in isokinetic peak torque occurred across age, independent of increases in FFM. The causes of the age effect for strength are speculative, but it may be due to developmental changes in neuromuscular function, alterations in the distribution of muscle mass as a percentage of FFM and/or the distribution of FFM across body segments.     

Facultative parasites and host respiration III. Tissue which is actively parasitised

Summary Fusarium oxysporium f.lycopersici andVerticillium albo-atrum caused an increase in the rate of respiration of tomato stem tissue.V. albo-atrum caused an increase in the rate of respiration of potato haulm tissue. By comparison of the respiration of 1 g ofV. alboatrum mycelium with 1 g fresh weight infected tomato stem tissue it was concluded that the respiration of the pathogen in situ does not contribute markedly to the respiratory increase. It is suggested that the increase in respiration has its origin in the metabolism of the host, possibly due to stimulation by a fungal respiratory toxin but not due to the augmentative effect of the pathogen's respiration.This work formed part of a Ph. D. thesis submitted to the University of London, July 1961.     

Distribution and abundance of sei whales off the west coast of the Falkland Islands

Little information exists on the current status of Southern Hemisphere sei whales (Balaenoptera borealis). We assessed their distribution and abundance along the west coast of the Falkland Islands (southwest Atlantic) during February and March 2018, using line transect and nonsystematic surveys. Abundance estimates were generated for a single survey stratum using design- and model-based approaches. Sightings of sei whales and unidentified baleen whales (most, if not all, likely to be sei whales) occurred from the coast to the 100 m depth isobath that marked the offshore boundary of the stratum. The modeled distribution predicted highest whale densities in King George Bay and in the waters between Weddell Island and the Passage Islands. Sei whale abundance was estimated as 716 animals (CV = 0.22; 95% CI [448, 1,144]; density = 0.20 whales/km²) using the design-based approach, and 707 animals (CV = 0.11; 95% CI [566, 877]; density = 0.20 whales/km²) using the model-based approach. For sei whales and unidentified baleen whales combined, the equivalent estimates were 916 animals (CV = 0.19; 95% CI [606, 1,384]; density = 0.26 whales/km²) and 895 animals (CV = 0.074; 95% CI [777, 1,032]; density = 0.25 whales/km²). The data indicate that the Falkland Islands inner shelf region may support globally important seasonal feeding aggregations of sei whales, and potentially qualify as a Key Biodiversity Area.     

Characteristics of insulin and glucagon release from the perfused pancreas, intact isolated islets, and dispersed islet cells

There are a variety of different tissue preparations which have been used to study secretion from the endocrine pancreas and there are considerable differences in the results obtained from these. The purpose of this study was to compare several preparations in one laboratory using the same rats, buffers, and radioimmunoassays. The preparations included the isolated perfused rat pancreas, fresh isolated intact islets and dispersed cells, and cultured islets and cells. Insulin release from the perfused rat pancreas at 2.8 mM glucose was so low that it could not be measured, such that over a 90-min time period the amount of insulin released was less than 0.004% of pancreatic insulin content. In contrast, islets in static incubation appear to release 2.0% of their stored content and dispersed cells appear to release 2.6% of their content. Samples were taken at early time points during incubations of fresh islets and dispersed cells, and it was found that almost all of the insulin found at the end of a 90-min incubation period was present during the first 5 min. It is therefore suspected that the true secretory rate of insulin at a low glucose concentration is far lower than had been generally appreciated. Glucagon release patterns showed similarities in that with isolated islets and dispersed cells a disproportionate amount of glucagon release was found during a 0- to 30-min incubation period when compared with the 30- to 90-min period. In summary, artifacts have been identified in some of the in vitro systems used for the study of endocrine pancreatic secretion and these deserve greater recognition.     

Characterization of Escherichia coli strains isolated from urine of secretors and non-secretors

Strains of Escherichia coli isolated from urine of secretors (242) and non-secretors (121) were compared for their serotype and their ability to express mannose-sensitive (MS) haemagglutinins and mannose-resistant (MR) haemagglutinins and to produce haemolysin. The results of the survey refuted our hypothesis that strains with characteristics associated with virulence, those with MR haemagglutinins and/or haemolysins, would be isolated more frequently from non-secretors. MR haemagglutinins were detected among 36.4% of isolates from secretors and 27.3% of isolates from non-secretors. Haemolysin production was detected among 19.8% of isolates from secretors and 12.5% of isolates from non-secretors. Both MR haemagglutinins and haemolysin were detected only on 12.4% of strains from secretors and 6.7% of strains from non-secretors.     

The effect of Mycoplasma arthritidis infection on the phagocytic activity of macrophages in rats and mice

The phagocytic activity of mononuclear phagocytes of A/J mice and Wistar rats was estimated by the carbon clearance test following injection of Mycoplasma arthritidis. In mice, the overall phagocytic activity was significantly increased at the end of the first week (P less than 0.0001), but the increase was marginal by the third and fourth weeks after injection. A significant increase in the relative weight of liver and spleen was observed even when phagocytic activity had returned to levels similar to those of controls (P less than 0.001). In rats, the overall phagocytic activity was significantly increased until the fourth week (P less than 0.00001). There was not, however, an increase in the relative weight of liver and spleen as observed for the mice. The results are discussed in the context of factors contributing to the pathogenic mechanisms responsible for differences in the patterns of arthritis due to mycoplasma observed in mice and rats.     

A comparison of tests for independence in the FBI RFLP data bases

Several tests of independence of alletic frequencies within and between loci have been compared, and it has been found that Fisher's exact test is the best test to use. When this test is applied to RFLP databases established by the FBI, paying no attention to the single-band problem, there is generally evidence for independence at one locus but not at two loci. When the test is restricted to double-banded entries in the databases; there is overall evidence for independence.     

Haemosiderin and tissue damage

High levels of haemosiderin occur in iron overload syndromes such as idiopathic haemochromatosis or secondary iron overload in thalassaemic patients; haemosiderin is the predominant iron-storage compound in such cases. It consists of a large aggregate of FeOOH cores, many of which have an incomplete shell of protein, and is probably derived from ferritin by lysosomal proteolysis. In addition, some chemical degradation of the ferritin cores appears to occur on conversion to haemosiderin. Other biochemical components are phosphate and magnesium, which may be adsorbed to the core surface, and perhaps certain lipids. Haemosiderin may have a central role, either directly or indirectly, in iron cytotoxicity and therefore the chemistry and biochemistry of this material warrants further study.