Respiratory losses

Infants and young children may present with dehydration due to increased respiratory losses and decreased intake.1,3 Rehydration... 

By comparison with carbon respiratory losses Newell and Linley (1989)... 

The microbial loop concept has been the prevailing paradigm for marine microbial food webs for two decades and has stimulated work on DOM sources and composition, rates of biomass production, transfer efficiencies, and respiratory losses (Benner, 1998 del Giorgio and Cole, 2000 Ducklow, 2000 Williams, 2000). The only major modification has arisen from new information on the abundance and ecology of viruses (Wilhelm and Suttle, 1999 Fuhrman, 1999, 2000). 

Plants and their individual parts display distinct patterns in their respiratory rate during development. One of the earliest studies on respiratory patterns was conducted on sunflower plants and component parts during an entire growing season (Kidd et al., 1921). In Jerusalem artichokes, total carbon respired from the leaves was calculated from the respiratory rate of different aged leaves x their weight (Hogetsu et al., 1960). The vertical distribution of leaf size (g dwt) and respiratory losses... 

Plant population density affected the amount of respiratory losses at the highest density (10 x 10 cm), the total respiratory losses increased markedly in June. At the lower densities (20 x 20... 

FIGURE 10.10 Vertical distribution by stem node of leaf respiratory losses and total leaf dry weight at four developmental stages during the growing season. (After Hogetsu, K. et al., Jpn. J. Bot., 17, 278-305, 1960.)... 

Hypernatremia in the setting of decreased ECF is caused by the renal or extrarenal loss of hypoosmotic fluid leading to dehydration. Thus once hypovolemia is established, measurement of urine Na" " and osmolality is used to determine the source of fluid loss. Patients who have large extrarenal losses have a concentrated urine (>800 mOsmol/L) with low urine Na (<20 mmol/L), reflecting the proper renal response to conserve Na and water as a means to restore ECF volume. Extrarenal causes include diarrhea, skin (burns or excessive sweating), or respiratory losses coupled with failure to replace the lost water. When gastrointestinal loss is excluded, and the patient has normal mental status and access to H2O, a hypothalamic disorder (tumor or granuloma) should be suspected, because the normal thirst response should always replace insensible water losses. 

Combining our N respiratory loss and urinary excretion measurements provides a minimum value for the rate of BCNU degradation in the rat about 40% in 1 h. It is of interest here to consider the data of Levin, Kabra, and Freeman-Dove (37) for the intact BCNU concentrations of six rat tissues after iv injection of 40 /imol/kg BCNU (cloroethyl-i<3) (37). Conversion of their data for 40 min after injection to units of relative concentration gives values between 0.1 and 0.2 for striated muscle, omental fat, liver, limg, and brain and a value of 0.8 for the kidney. If the concentrations of the first five tissues were typical of the body as a whole, then only 10-20% of the injected BCNU was intact at 40 min. If this estimate is correct, then most of the breakdown of BCNU in the rat does not involve the production of N2. 

Application of Eq. 2 to the fluorescence data, such as those presented in Fig. 1 provides a basis for calculating photos3mthetic electron transport rates in real time, non—destructively. We compared photosynthetic rates with those measured using radiocarbon during 6 h incubations (Fig. 2). Our results reveal that the fluorescence derived estimates of photosynthesis explain 79% of the variance in the photosynthesis predicted from radiocarbon fixation. Considering that photosynthesis calculated from variable fluorescence does not include respiratory losses, while that from radiocarbon has some respiratory... 

The two- to fourfold variation in sucrose cost per NHj assimilated (Fig. 3B) is not faithfully reflected in respiratory losses of CO2, since dark fixation inputs of CO2 apply to certain compounds (e.g., aspartate and asparagine) but not at all, or to only a minor extent, in the case of others. Net CO2 exchange values therefore range from a net fixation input of 0.58 and 1.08 CO2/NH3 in the case of glutamate and aspartate, respectively, to a net evolution of 0.02 to 0.53 CO2/NH3 for ureide, citrulline, and proline. Based on these calculations the type of products selected by a plant for export of assimilated nitrogen might aJter significantly the apparent respiration status (respiratory quotient) of its assimilatory tissues. 

---