Lactate modeling and its application to endurance training

1. 1. In this short review, previous studies regarding the modeling of lactate (La) response to exercise and its application to endurance training have been summarized.

2. 2. Additionally the result of a recent study by the present authors are shown.

3. 3. Several models for La response to step and ramp exercise are already proposed and deductions derived from them are used for practical purposes such as the prediction of race performance in middle-and long-distance runners as well as for construction of their training regimens.

4. 4. Only a limited number of models however have tried to quantify whole body La kinetics to exercise in humans concomitantly with describing physiological mechanisms underlying the observed phenomenon.

5. 5. In a recent study described further in this paper a 2 compartment model was used for the purpose of clarifying the current “La production vs degradation” controversy during La adaptation to training.

6. 6. It was determined from this investigation that the La metabolic clearance rate during recovery is enhanced by the endurance training.

7. 7. This is in accordance with another recent observation of an increased La metabolic clearance rate at high absolute work rates and all relative work rates during exercise.

Turnover of cell surface-bound capsular polysaccharide in Staphylococcus aureus

The capsular polysaccharide (CPS) of Staphylococcus aureus strain Smith was labelled by growth of bacteria in the presence of radioactive N-acetylglucosamine and was separated from labelled cell wall components by affinity chromatography on wheat germ agglutinin following dissolution of the cells by lysostaphin. The products were partially characterised chemically and immunochemically. Similar labelled components were found in the culture fluid during growth. In a pulse-chase experiment, cell-bound CPS was released continuously into the culture fluid at the same rate as cell wall turnover and there was no evidence of direct excretion of CPS.     

Oral water ingestion in the pulmonate freshwater snail,Lymnaea stagnalis

InLymnaea stagnalis, oral uptake of ambient medium was studied using⁵¹Cr-ethylenediaminetetra-acetic acid. In normal snails Cr-ethylenediaminetetra-acetic acid uptake showed two components: a high uptake rate within the first hour followed by moderate uptake proportional with time. The tracer accumulated mainly in the digestive system. All animals showed initial, transient uptake. Moderate uptake proportional with time did not occur in snails in which the buccal ganglia had been extirpated, in which both the buccal ganglia had been extirpated and the oesophagus was sectioned, or in snails provided with an oesophageal fistula. These snails did not accumulate tracer in the intestinal system. This type of tracer accumulation clearly represented oral ingestion of surrounding water. The oral water ingestion rate ranged from 8 to 12 μl·h⁻¹·g⁻¹. Assuming complete absorption, this accounts for 20–30% of the urine production rate. At low external concentrations the contribution of oral water ingestion to Na⁺ balance is negligible. However, its importance will grow with increasing external concentrations and becomes a major factor at higher concentrations. The ingestion rate increased almost sixfold when starving snails were allowed to feed. It is suggested that oral water ingestion is a consequence of making bite cycles and swallowing.     

Cub growth and maternal care in cheetahs

Using cub growth as an index, I examine the influence of maternalnutrition, litter size, and cub sex on maternal care in cheetahs(Acinonyx jubatus) and compare cub and litter growth rates withthose of other large feilds. Seventy-nine free-living cheetahcubs in 21 litters from 15 mothers were weighed at least oncebetween 6 and 48 days of age. Eleven litters were weighed atthe beginning and end of a 5-day observation of their mothers.The mean cub growth rate varied significantly between litters,due primarily to differences in maternal food intake. Growthdeclined sharply when maternal food intake was less than 1.5kg/ day, but did not increase with greater levels of food intake.Lower limits of growth rates may therefore have been set bythe mother's food intake, whereas upper limits may be set bythe intrinsic physiological ability of cubs to grow. Althoughmale cubs were heavier than female cubs in the same litter whenfirst weighed, major differences in growth rate between thesexes were not apparent at this stage. Both cheetah cubs andlitters grow fast relative to other large felids, and I arguethat this may be an adaptation to the high rate of cheetah juvenilemortality from predation.     

Contest and scramble competitions inCallosobruchus maculatus (Coleoptera: Bruchidae) II. Larval competition and interference mechanisms

Competition between contest and scramble strategists was examined using two strains of Callosobruchus maculatus, the contest strain (iQ) and the scramble strain (tQ). The direct larval interference experiment within each strain showed that the contest strain performed strong direct interference throughout its larval stage against the conspecific opponent(s). The scramble strain also performed its interference, but only during the 3rd and the 4th larval stages. The inter-strain larval competition experiments inside a large and small mung bean (Vigna radiata) showed that the contest strain was, in general, superior to the scramble strain in competition, but the competition results were density- and frequency-dependent. In the large beans, the proportion of adult emergence of the contest strain increased with the increase of its own initial density but decreased as the initial density of the scramble strain increased. The shape of the proportion of adult emergence became nonlinear in the small beans. The cause of the complexity of inter-strain competition results was discussed in the light of the difference in larval interference ability between the two strains.     

The structure and function of phytochrome A: the roles of the entire molecule and of its various parts

Phytochrome A is readily cleavable by proteolytic agents to yield an amino-terminal fragment of 66 kilodalton (kDa), which consists of residues 1 to approximately 600, and a dimer of the carboxy-terminal 55-kDa fragment, from residue 600 or so to the carboxyl terminus. The former domain, carrying the tetrapyrrole chromophore, has been studied extensively because of its photoactivity, while less attention has been paid to the non-chromophoric portion until quite recently. However, the evidence gathered to date suggests that this domain is also of great improtance. We present here a review of the structure and the biochemical and physiological functions of the two domains, of parts of these domains, and of the cooperation between them.     

Injury Delays Stem Cell Apoptosis after Radiation in Planarians

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Metabolic Reconfiguration in C. elegans Suggests a Pathway for Widespread Sterol Auxotrophy in the Animal Kingdom

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