Measuring food intake with digital photography

The digital photography of foods method accurately estimates the food intake of adults and children in cafeterias. When using this method, images of food selection and leftovers are quickly captured in the cafeteria. These images are later compared with images of 'standard' portions of food using computer software. The amount of food selected and discarded is estimated based upon this comparison, and the application automatically calculates energy and nutrient intake. In the present review, we describe this method, as well as a related method called the Remote Food Photography Method (RFPM), which relies on smartphones to estimate food intake in near real-time in free-living conditions. When using the RFPM, participants capture images of food selection and leftovers using a smartphone and these images are wirelessly transmitted in near real-time to a server for analysis. Because data are transferred and analysed in near real-time, the RFPM provides a platform for participants to quickly receive feedback about their food intake behaviour and to receive dietary recommendations for achieving weight loss and health promotion goals. The reliability and validity of measuring food intake with the RFPM in adults and children is also reviewed. In sum, the body of research reviewed demonstrates that digital imaging accurately estimates food intake in many environments and it has many advantages over other methods, including reduced participant burden, elimination of the need for participants to estimate portion size, and the incorporation of computer automation to improve the accuracy, efficiency and cost-effectiveness of the method.

Digital photography: a new method for estimating food intake in cafeteria settings

OBJECTIVE

The primary objective of this study was to test the comparability of digital photography and visual estimation procedures for estimating food intake.

RESEARCH METHODS AND PROCEDURES

The study sample included 71 breakfast meals and 59 lunch meals eaten in a university cafeteria during a single day. A total of 66 different foods were employed as test foods that could be selected by the students. Food selections and plate waste, as estimated by digital photography and visual estimation, were compared. For digital photography, three observers independently estimated portion sizes of each food item based upon digital photographs. One observer estimated portion sizes in the cafeteria setting, using visual estimation, a method that has been validated in other studies.

RESULTS

To test the accuracy of the two procedures for measuring food intake, the estimates of food weights derived from both procedures were compared using Bland-Altman regression. In comparison to visual estimation, the digital photography method yielded comparable estimates of food selections, plate waste, and total food intake for seven of nine comparisons. The two methods of estimating food portions yielded comparable results for most (78%) types of foods. The two methods also yielded similar variability.

DISCUSSION

These findings suggest that the digital photography method is an alternative to the traditional method of estimating food intake via direct observation.

Depletion of rat liver glucocorticoid receptor hormone-binding and its mRNA in sepsis

Glucocorticoid receptor (GR) hormone-binding activity, its physical characteristics, and GR mRNA levels were studied in the liver, brain and muscle of normal (saline-injected) and hypermetabolic septic rats 24 h after the subcutaneous injections of E. coli. The GR levels (hormone-binding activity) declined by about 40%, 56%, and 40% in septic liver, brain, and muscle cytosol, respectively. The mechanism of the decrease in the GR levels in sepsis was studied in liver. The GR levels remained low (45% of control hormone-binding) even after 48 h of E. coli administration. The decrease in the liver GR occurred in the 9S untransformed GR. The 9S GR from septic liver transformed to the 4S form in proportions comparable to the control liver GR. In addition, the 4S GR from control and septic liver was capable of binding to DNA-cellulose to a similar extent. The GR mRNA level in septic liver declined by about 30%. Thus, a decrease in GR hormone-binding activity in sepsis appears to be due to a decline in the steady-state GR mRNA level and not from a change in the qualitative properties of the GR protein.

Regulation of glucocorticoid receptor protein and mRNA levels

The level of steroid receptors in target cells affects the responsiveness of the cell to the hormone. In mouse AtT-20 cells, it has been shown that chronic glucocorticoid treatment causes a down-regulation of glucocorticoid receptor (GR) levels (F. Svec and M. Rudis, J. Biol. Chem., 256:5984-5987, 1981). The current study shows that chronic hormone treatment reduces the amount of GR mRNA to about 50% of that in untreated cells. A combined treatment of the cells with an inhibitor of RNA transcription and the glucocorticoid hormone causes a more rapid decrease in steady-state GR mRNA levels than either agent alone. This suggests that glucocorticoids regulate the expression of the GR gene posttranscriptionally, perhaps via destabilization of the GR mRNA. An additional transcriptional regulation by the steroid hormone is not ruled out by this observation. It was also found that heat shocking a variety of cell types at 42 degrees C not only causes an induction of heat shock proteins but also results in a dramatic decrease in the level of glucocorticoid-binding activity. GR labeled with a covalent ligand (dexamethasone 21-mesylate) was also reduced by heat shock, implying that heat shock caused an increased degradation in the GR protein itself. Finally, in vitro studies show that the GR is degraded in an ATP- and tRNA-dependent fashion in rabbit reticulocyte lysate. It therefore seems likely that the GR is degraded by the ubiquitin-dependent proteolytic pathway. Because ubiquitin is itself a heat shock protein, this may be the reason that the GR is rapidly degraded in heat-shocked cells. These studies point to possible mechanisms whereby the responsiveness of the cell to steroid hormones is altered by the regulation of the steroid receptor protein and mRNA levels.

Potentiation of the toxicity of basic peptides from rattlesnake venoms by sodium acetate

The potentiating effect of sodium acetate on the toxicity of crotamine from Crotalus durissus terrificus venom, E toxin from Crotalus horridus horridus venom, and myotoxin a from Crotalus viridus viridis venom was examined. Subcutaneous injection of 6.3 mg/kg body weight of either crotamine or E toxin in 0.6 ml of water or myotoxin a in 0.6 ml of 0.05 M Tris/0.1 M NaCl buffer, pH 9.0, failed to produce lethality in mice. Injection of either E toxin or crotamine at doses of 4.0 mg/kg in 0.6 ml of 20 mM phosphate, pH 7.2, containing 1 M sodium chloride also failed to produce lethality. However, when any of the toxins were injected in 0.4 ml of 1 M sodium acetate, pH 7.0, lethality was observed. LD50 values of 1.43 mg/kg for E toxin, 1.39 mg/kg for crotamine and 0.56 mg/kg for myotoxin a were determined under these conditions. Lethality was also observed when either sodium propionate or sodium butyrate was used as a carrier for E toxin. The effect of these two buffers on crotamine and myotoxin a was not examined. Injection of E toxin s.c. in water followed at various time intervals with i.p. injections of 1 M sodium acetate produced lethality, even when the acetate was injected up to 4 hr after the toxin challenge.

Pharmacokinetics of cefpimizole in normal humans after single- and multiple-dose intravenous infusions

The pharmacokinetics of cefpimizole (free acid equivalents of cefpimizole sodium), a broad-spectrum cephalosporin antibiotic, were determined after single- and multiple-dose 20-min intravenous infusions of 1, 2, and 4 g. The kinetics of single-dose administration of cefpimizole correspond to a two-compartment model with an average apparent volume of distribution of 20.0 +/- 3.5 liters, a distribution rate constant of 2.24 +/- 1.00 h-1, and a terminal rate constant of 0.358 +/- 0.036 h-1 (half-life, 1.9 h). The total body clearance was 118.6 +/- 20.2 ml/min. The primary route of elimination for cefpimizole was the renal route, with approximately 80% of the administered dose excreted as the parent compound. The elimination rate constant, as calculated from urinary excretion data, was 0.339 +/- 0.043 h-1, which is in close agreement with the terminal rate constant for plasma. Renal clearance of cefpimizole was 96.2 +/- 17.3 ml/min. Dose proportionality over the three dose levels was obtained from area under the plasma curve and cumulative urinary excretion data. The results of the multiple-dose study indicated that no apparent change in the distribution or elimination kinetics of cefpimizole occurred after the administration of 1-, 2-, and 4-g doses for 7 days, three times a day. The kinetics from the multiple-dose study were in close agreement with those from the single-dose study. No accumulation of cefpimizole occurred, and nondetectable levels was observed 24 h after administration of the last dose. Peaks that could be attributed to metabolites of cefpimizole were not observed during high-pressure liquid chromatographic analysis of either plasma or urine specimens.

Resistance of a hemorrhagic proteinase from timber rattlesnake venom to proteolytic degradation

The proteolytic activity of hemorrhagic proteinase IV isolated from timber rattlesnake (Crotalus horridus horridus) venom was resistant to inactivation by trypsin, pronase and the proteolytic IIt fraction isolated from timber rattlesnake venom. SDS-polyacrylamide gel electrophoresis of the hemorrhagin incubated alone and with the three proteinases revealed that the addition of trypsin or the IIt fraction caused little apparent degradation of the hemorrhagin, whether or not the samples were reduced prior to electrophoresis. SDS electrophoresis of the hemorrhagin after incubation with pronase revealed a single band of 28,000 apparent molecular weight (as compared to 52,000 for the original hemorrhagin) if the samples were not reduced prior to electrophoresis, and a single band of 17,000 if reduced. If the hemorrhagin was reduced and alkylated, it was much more susceptible to hydrolysis by all three proteinases.