Logarithm Of Body Weight Research Articles

Factors affecting the myocardial activity acquired during exercise SPECT with a high-sensitivity cardiac CZT camera as compared with conventional Anger camera

Injected doses are difficult to optimize for exercise SPECT since they depend on the myocardial fraction of injected activity (MFI) that is detected by the camera. The aim of this study was to analyse the factors affecting MFI determined using a cardiac CZT camera as compared with those determined using conventional Anger cameras. Factors affecting MFI were determined and compared in patients who had consecutive exercise SPECT acquisitions with (201)Tl (84 patients) or (99m)Tc-sestamibi (87 patients) with an Anger or a CZT camera. A predictive model was validated in a group of patients routinely referred for (201)Tl (78 patients) or (99m)Tc-sestamibi (80 patients) exercise CZT SPECT. The predictive model involved: (1) camera type, adjusted mean MFI being ninefold higher for CZT than for Anger SPECT, (2) tracer type, adjusted mean MFI being twofold higher for (201)Tl than for (99m)Tc-sestamibi, and (3) logarithm of body weight. The CZT SPECT model led to a +1 ± 26% error in the prediction of the actual MFI from the validation group. The mean MFI values estimated for CZT SPECT were more than twofold higher in patients with a body weight of 60 kg than in patients with a body weight of 120 kg (15.9 and 6.8 ppm for (99m)Tc-sestamibi and 30.5 and 13.1ppm for (201)Tl, respectively), and for a 14-min acquisition of up to one million myocardial counts, the corresponding injected activities were only 80 and 186 MBq for (99m)Tc-sestamibi and 39 and 91 MBq for (201)Tl, respectively. Myocardial activities acquired during exercise CZT SPECT are strongly influenced by body weight and tracer type, and are dramatically higher than those obtained using an Anger camera, allowing very low-dose protocols to be planned, especially for (99m)Tc-sestamibi and in non-obese subjects.

Lipid peroxidation and the antioxidant system of the brain of developing chicken embryo

double yolked eggs (9·50 g/kg) was larger than in single yolked eggs (7·57 g/kg). In addition, the proportion of yolk in single yolked eggs was, as might have been expected from the egg weight data, closely associated with the logarithm of body weight at 1st egg (Table). Yolk proportion in double yolked eggs was not signiŽ cantly correlated with body weight. HUSSEIN, S.M., HARMS, R.H. & JANKY, D.M. (1993) Effect of age on the yolk to albumen ratio in the chicken egg. Poultry Science, 72: 594–597. MARCH, B.E. & MACMILLAN, C. (1990) Linoleic acid as a mediator of egg size. Poultry Science, 69: 634–639. LEWIS, P.D., PERRY, G.C. & MORRIS, T.R. (1994) Effect of breed, age and body weight at sexual maturity on egg weight. British Poultry Science, 35: 181–182.

Effect of prepuberal and postpuberal gonadectomy on heat production measured by indirect calorimetry in male and female domestic cats

Abstract Objective To use indirect calorimetry to compare heat production between gonadectomized and sexually intact male and female cats. Design Male (n = 6) and female (n = 6) kittens were gonadectomized at 7 weeks or 7 months of age, or left sexually intact. Body heat production was measured by indirect calorimetry in all cats at 12, 18, and 24 months of age. Animals 18 male and 18 female clinically normal domestic shorthair cats. Procedure Heat production was measured, using an open-circuit, respiratory, indirect calorimeter. All cats underwent calorimetry at 12, 18, and 24 months of age. The heat coefficient, a measure of resting metabolic rate, was calculated for each cat at each test; heat coefficient is defined as logarithm of heat (kcal/h) divided by logarithm of body weight (kg). Results Heat production did not vary with age in male or female cats. Heat coefficient was higher in sexually intact male and female cats than in gonadectomized male and female cats at 12, 18, and 24 months of age (12 months, females, P < 0.01, males, P = 0.04; 18 months, females, P < 0.01, males, P = 0.02; and 24 months, females and males, P < 0.01). Conclusions These data suggest that resting metabolic rate in cats decreases after gonadectomy. Clinical Relevance A decrease in metabolic rate is synonymous with a decrease in caloric requirements. Gonadectomized animals fed in a manner similar to sexually intact animals may be predisposed to obesity and its sequelae.(Am J Vet Res 1996;57:371-374)

Models of aquatic biomass size spectra and the common structure of their solutions

Mathematical models of aquatic biomass body-size spectra are usually interpreted as single-valued functions of the body weight of organisms. Where these spectra are recognized as dependent on predator-prey energy transfers, it is shown that solutions of the models consist of a smoothly varying or linear part plus a neglected but not negligible part that is periodic in the logarithm of body weight. The models can also be interpreted as yielding multiple spectra, in which the spectrum for a given trophic position is replicated at regular intervals over the range of body weight. In either interpretation the models support empirical data exhibiting significant quasi-periodic departures from a smoothly varying or straight line, without implying a priori knowledge of underlying mechanisms. Under some conditions the biomass size spectrum in an ecosystem describable by a multiple spectra ecosystem model may be indistinguishable from one characterized by a single-valued spectrum.

Allometry of Femoral Heads of Animals with Their Body Weight.

In the present study, the relationship between the femoral head diameter and the body weight of animals is shown. The diameter of femoral heads of fifteen terrestrial mammalian animals were measured directly from their skeletons. The body weight of these animals was referred from literature. Additionally, both the mean values of the femoral head diameters and the body weights of Japanese adult men and women were referred from the literature. The logarithm of femoral head diameter of these animals were plotted against the logarithm of body weight. The positive correlation was significant (p<0.01). The gradient of the regression line was 0.29. It showed that femoral head diameter is proportional to (body weight) 0.29. By analysis, we showed that this relationship can be deduced from the condition of uniform contact pressure or uniform performance of squeezed-film lubrication.

The relationship between organ weights and body weights, facial dimensions, and dental dimensions in a population of olive baboons (Papio cynocephalus anubis).

AbstractQuestions concerned with the relationship between organ weights and body weight on an intraspecific level are best answered by using a sample of animals collected in the wild from a single locale during a single season. The organ weights and body weights for this study were obtained from the necropsy reports prepared in the field (Athi Plain, Kenya) by H. C. McGill, Jr. on 36 adult animals (18 males and 18 females). Dental and facial measurements were taken by M.I. Siegel.In order to avoid erroneous results produced by statistical treatment of combined sex samples of sexually dimorphic species, data on the sexes were analyzed separately. Means and standard deviations are reported for selected organ weights and body dimensions (heart, lung, liver, spleen, kidney, adrenal, brain, and pancreas weights, crown–rump length, crown–heel length, head circumference, chest circumference, and body weight). All of the above measures were significantly (p&lt;0.05) different between the sexes. Logarithms of these measures were significantly correlated with the logarithm of body weight in males for heart, lung, liver, spleen, kidney, and adrenal weights, crown–heel length, and head and chest circumference, and in females for crown–heel length, heart, liver, and kidney weights. Partial correlational analysis, removing the effects of body size (weight), showed mostly negative correlational relationships between dental and visceral dimensions. Most of the correlations between facial and visceral dimensions were negative. Allometric equations were calculated for the dental, facial, and visceral dimensions versus body weight, and are compared with prior published results.

Relationship between liver size and body size.

WITH THE ADVENT of newer technics for organ visualization such as radionuclide scanning, it is helpful to know the normal range of organ size relative to body size. Unfortunately, little information on this subject is available. For example, most references give the range of liver weight in the adult male or female without giving the relationship to body height or weight (1–5). In a series of autopsies, Stowens related liver weight to body height for children (6). The only data, however, on the relationship of liver weight and size to body weight, height, and/or surface in adults are the studies made by Frericks (7) of 24 persons. We selected, therefore, a series of 550 cases from 5,000 autopsy protocols of the Department of Pathology of The Johns Hopkins Hospital, plus 75 nonhospitalized autopsied cases (60 males and 15 females) from the files of the Medical Examiner's Office of the State of Maryland. From these cases studied, we were able to relate liver size to body size. Materials and Methods The 550 cases were selected on the basis of the following criteria: (a) no clinical, laboratory, or autopsy evidence of hepatic pathology; (b) no evidence of cardiovascular disease, such as cardiac decompensation or increased peripheral venous pressure ; (c) no evidence of systemic disease of the liver, such as infection, lymphoma, leukemia, or collagen disease. These same criteria were used in the selection of the cases of the Medical Examiner. Such cases were limited to those persons dying instantaneously from gunshot wounds, severe crushing injuries, falls from high structures, or automobile accidents. Cases were not included if there was evidence of significant hemorrhage prior to death. Data on age, sex, body weight and height, and liver weight were tabulated. Measurements of the width, height, and depth of the liver were made at the time of autopsy in only the hospital series. Body surface area was determined from a nomogram based on the formula of DuBois and DuBois(11): Results Relationship Between Liver Weight and Body Weight: The body weights of the subjects were grouped in 5 kg increments. The mean liver weight (±1 S.D.) for each increment is shown in Figure 1. It can be seen that as body weight increases, the liver weight increases, but at a slower rate. According to Stahl (8), the relationship between body weight and organ weight in animals is more linear if one relates the exponential function of each. Therefore, the logarithm of body weight was plotted as the abscissa, and the logarithm of the mean liver weight as the ordinate (Fig. 2). For a body weight between 3 and 20 kg the relationship was a nearly straight line with a slope of about 45 °. From 20–30 kg of body weight the rate of increase in liver weight decreased but remained nearly linear. The liver is reported to be 3.8 per cent of body weight at birth (9).

Relationship of lethal toxic dose to body weight of the mouse

LD50's have been determined for tetrodotoxin, hemicholinium-3, d-tubocurarine, strychnine, α-naphthylthiourea, 48–80 (a histamine liberator), picrotoxin, sodium fluoroacetate, McN-A-343 (a ganglionic stimulant), hexamethonium chloride, pentamethylene tetrazol, sodium pentobarbital, atropine, histamine, and sodium barbital by intraperitoneal injection into small, medium, and large male and female mice. Values have also been determined for histamine and α-naphthylthiourea by intravenous injection. An attempt has been made to describe the relationship of toxicity to body weight for each of these instances. While the most common relationship found is a direct linear one characterized by a slope of unity when the logarithm of dose is plotted against the logarithm of body weight, a significant number of cases show a variety of other relationships to preclude any overall generalization. Only hemicholinium-3 in the female mouse came close to duplicating the published experience with botulinal and tetanal toxins. Experimental evidence is provided to demonstrate that the character of the relationship may vary with drug identity, route of administration, and sex of the test organism. There is no reason to expect that species, strain, and the other factors known to modify the intensity of drug action will not also modify the relationship of effective dose to body weight. The influence of each of these factors is, however, not predictable on the basis of present knowledge.

Thyroid secretion rate in the neonatal rat

Neonatal thyroid secretion rates (TSR) were determined by a direct output method. The neonatal rat has a low level of thyroidal function at birth, and this condition persists until the animal weighs 22 gm. Thereafter, there is an abrupt increase in TSR and the thyroid iodine content, both of which, from that time on, vary linearly with the logarithm of body weight. This relationship is maintained at least until the rats weight 244 gm, at an age of about 60 days. The existence of a mother-infant iodine cycle was confirmed. Approximately 9.36% of the average 131I count in thyroid glands of tagged litter-mates was transferred within 48 hours via the mother's milk to an untagged foster rat of the same age. The number of rats in the litter, their ages, and their weights had no influence on the amount of cycled iodine.

Exchangeable body potassium and sodium in patients in congestive heart failure

Total exchangeable mass of potassium was measured in 43 patients with longstanding heart disease; 30 were in congestive heart failure, 22 recovered, 8 died. Exchangeable mass of sodium was measured simultaneously in 29 patients. In 11 subjects, measurements were made on several occasions. These data, and some previously published, are evaluated, visually, using relationships calculated to obtain in controls between the logarithm of exchangeable mass of potassium (or sodium) and the logarithm of body weight and the logarithm of body height. Where values are available for Na e, “oedema-free” body weight was calculated: assumptions and approximations are discussed. Some subjects were weighed when free from oedema. Evaluation of exchangeable potassium is facilitated by the use of “oedema-free” weight. Excess of sodium in congestive failure can be extensive; subnormal serum levels of sodium commonly coexist; excess can be present in the absence of oedema or failure. It is submitted that excess of sodium reflects cellular gain as well as accumulation of oedema. Dearth of potassium was common in our subjects; serum potassium levels may be high. In addition to cachexia, cellular depletion contributes towards potassium dearth. The extent of cachexia was calculated from comparison of standard weight and observed, or calculated, “oedema-free” weight. The extents of sodium excess, potassium dearth, and cachexia did not differ in patients dying during the episode of congestive failure, from those subsequently recovering.

ÉTUDE DE L'ACCLIMATION THERMIQUE CHEZ LA LIMACE ARION CIRCUMSCRIPTUS

Slugs of the species Arion circumscriptus were acclimated to temperatures of 5°, 8° 10°, 20°, and 25 °C respectively. After acclimation, metabolic rate was determined, either as oxygen consumption, at 30° and 20°, or by direct calorimetry, at 25° and 12.5°, At all given exposure temperatures, the average metabolic rate was lower, by 1% to 1.5%, for each degree of increase in the acclimation temperature. When the logarithms of total O2 consumption or heat production per hour are plotted against the logarithms of body weight, the regression line obtained for slugs acclimated to heat stands below that obtained for slugs acclimated to cold; the slope is also slighter for the warm-acclimated slugs than for the cold-acclimated, so that the distance between corresponding points of two such curves is larger in the righthand side of the graph, where the large specimens are represented, than in the lefthand side where the small specimens are shown. This would imply that an increase in the acclimation temperature reduces metabolic rate to a proportionately greater extent in the larger specimens than it does in the smaller ones. The value of the slope, which is inversely correlated with acclimation temperature, is also inversely correlated with the experimental temperature at which metabolism is determined.

Cytochrome oxidase activity and body weight in rats and in three species of large animals.

Study of the relationship of cytochrome oxidase activity of certain tissues to the body weight has been extended to include three species of large animals. In the comparison of rats, sheep, swine and cattle, the cytochrome oxidase activity of skeletal muscle (principally of the gracilis) was found to be roughly an inverse function of body weight. A logarithmic regression of –0.239 was calculated. Although the cytochrome oxidase activity per unit weight of liver in the sheep, swine and cattle series does not reflect the variation in body mass, the regression of the logarithm of total liver cytochrome oxidase activity on the logarithm of body weight was calculated to be 0.674. The data support the concept that the summated total measurable cytochrome oxidase activity is very nearly proportional to body weight to the 3/4 power and, hence, to basal metabolism.

Glucose tolerance in relation to obesity and food intake.

Glucose tolerance tests were carried out on two strains of mice, one highly susceptible, the other only moderately susceptible to nutritional obesity. With glucose administered on the basis of body weight or fat-free weight, the highly susceptible strain disposed more rapidly of the administered glucose than did the moderately susceptible strain. Fasting blood sugar levels in both strains were found to increase with the logarithm of body weight. These observations are not readily explained in terms of the ‘glucostatic’ theory of the control of food intake.

Collagen and hexosamine content of femurs of rats.

SummaryThe collagen and hexosamine contents of the femurs of growing rats were determined. Regression equations were derived upon the basis that there is a linear relationship between the logarithm of body weight and of femur length and the logarithm of the quantity of collagen and hexosamine. Rate of collagen deposition decreases somewhat as the animal grows. Rate of deposition of hexosamine-containing material, decreases markedly so that the ratio of hexosamine to collagen decreases with growth.

The collagen and hexosamine content of the skin of normal and experimentally treated rats

The collagen and hexosamine contents of the skin of growing rats were determined. Regression equations were derived upon the basis that there is a linear relationship between the logarithm of body weight and logarithm collagen, logarithm body weight and logarithm hexosamine, logarithm body area and logarithm collagen, and logarithm body area and logarithm hexosamine. The collagen content of the skin increases much more rapidly than the increase in weight. The hexosamine content increases with weight more nearly in a proportional manner so that the ratio of hexosamine to collagen falls as the weight increases. Several pilot experiments were carried out to determine the effects of a variety of factors upon the production of hexosamine and collagen in skin.

Changes in oxygen uptake and peptidase activity of rat thymus during growth and after adrenalectomy.

In male Sherman rats there is a straight line relationship between the logarithm of thymus weight and the logarithm of body weight until the animal weighs about 200 gm. With a further increase in body weight the thymus involutes but the extent of involution is extremely variable. The oxygen uptake of thymus suspensions and the maintenance of the respiration rate decrease with increase in body weight, both in the presence and absence of added glucose. Glucose added to the medium has little effect upon the respiration rate of the thymus of young animals but stimulates the respiration rate of the glands as the animals grow older. Thymus suspensions from adrenalectomized and sham-operated rats do not differ in their respiration rate or in their peptidase activity as measured by the ability to hydrolyze glycylglycylglycine.