ABSTRACT
Did dinosaurs grow in a manner similar to extant reptiles, mammals or birds, or were they unique? Are rapid avian growth rates an innovation unique to birds, or were they inherited from dinosaurian precursors? We quantified growth rates for a group of dinosaurs spanning the phylogenetic and size diversity for the clade and used regression analysis to characterize the results. Here we show that dinosaurs exhibited sigmoidal growth curves similar to those of other vertebrates, but had unique growth rates with respect to body mass. All dinosaurs grew at accelerated rates relative to the primitive condition seen in extant reptiles. Small dinosaurs grew at moderately rapid rates, similar to those of marsupials, but large species attained rates comparable to those of eutherian mammals and precocial birds. Growth in giant sauropods was similar to that of whales of comparable size. Non-avian dinosaurs did not attain rates like those of altricial birds. Avian growth rates were attained in a stepwise fashion after birds diverged from theropod ancestors in the Jurassic period.
Subject(s)
Biological Evolution , Birds/growth & development , Reptiles/growth & development , Animals , Reptiles/classification , Reptiles/physiologyABSTRACT
Sesamoid bones form within tendons in regions that wrap around bony prominences. They are common in humans but variable in number. Sesamoid development is mediated epigenetically by local mechanical forces associated with skeletal geometry, posture, and muscular activity. In this article we review the literature on sesamoids and explore the question of genetic control of sesamoid development. Examination of radiographs of 112 people demonstrated that the relatively infrequent appearances of the fabella (in the lateral gastrocnemius tendon of the knee) and os peroneum (in the peroneus longus tendon of the foot) are related within individuals (P < 0.01). This finding suggests that the tendency to form sesamoids may be linked to intrinsic genetic factors. Evolutionary character analyses suggest that the formation of these sesamoids in humans may be a consequence of phylogeny. These observations indicate that variations of intrinsic factors may interact with extrinsic mechanobiological factors to influence sesamoid development and evolution.
Subject(s)
Biological Evolution , Sesamoid Bones , Adult , Aged , Aged, 80 and over , Animals , Foot/anatomy & histology , Foot/diagnostic imaging , Gene Expression Regulation, Developmental , Humans , Knee/anatomy & histology , Knee/diagnostic imaging , Middle Aged , Models, Biological , Osteoarthritis/etiology , Phylogeny , Radiography , Sesamoid Bones/diagnostic imaging , Sesamoid Bones/embryology , Sesamoid Bones/growth & developmentABSTRACT
Dinosaur dentine exhibits growth lines that are tens of micrometers in width. These laminations are homologous to incremental lines of von Ebner found in extant mammal and crocodilian teeth (i.e., those of amniotes). The lines likely reflect daily dentine formation, and they were used to infer tooth development and replacement rates. In general, dinosaur tooth formation rates negatively correlated with tooth size. Theropod tooth replacement rates negatively correlated with tooth size, which was due to limitations in the dentine formation rates of their odontoblasts. Derived ceratopsian and hadrosaurian dinosaurs retained relatively rapid tooth replacement rates through ontogeny. The evolution of dental batteries in hadrosaurs and ceratopsians can be explained by dentine formation constraints and rapid tooth wear. In combination with counts of shed dinosaur teeth, tooth replacement rate data can be used to assess population demographics of Mesozoic ecosystems. Finally, it is of historic importance to note that Richard Owen appears to have been the first to observe incremental lines of von Ebner in dinosaurs more than 150 years ago.
Subject(s)
Biological Evolution , Paleodontology , Tooth , Animals , Dentition, PermanentABSTRACT
Two diets were formulated to contain 30% NDF (DM basis) but differed in source of NDF and type of concentrate. One diet contained approximately 70% alfalfa silage and 30% corn grain (89% of NDF from forage) and the other diet contained about 50% alfalfa silage and 50% barley grain (65% of NDF from forage). Diets were fed to 12 cows in a short production trial, a total collection digestion experiment, and a rate of passage study. Cows fed the alfalfa-corn diet produced more 4% FCM (22.4 vs. 20.7 kg/d) than did cows fed the alfalfa-barley diet. Intake of DM (3.7% of BW), NE1 (35 Mcal), and NDF (1.1% of BW) were similar between diets, but due to differences in diet composition, intake of ADF was greater by cows fed alfalfa-corn than by cows fed alfalfa-barley. Digestibilities of DM, NDF, and CP were not affected by diet, but hemicellulose digestion was higher and cellulose and ADF digestibilities were lower by cows fed alfalfa-barley diets. Cows fed alfalfa-corn diet had a higher ruminal acetate to propionate molar ratio. No effect of diet was observed on turnover kinetics of the forage, concentrate, or liquid markers. These data show that forage to grain ratio and source of starch must be considered prior to recommending that diets be balanced for NDF.
Subject(s)
Cattle/metabolism , Dietary Fiber/metabolism , Digestion , Starch/metabolism , Analysis of Variance , Animals , Cellulose/metabolism , Fatty Acids, Volatile/analysis , Female , Hordeum , Hydrogen-Ion Concentration , Lignin/metabolism , Medicago sativa , Polysaccharides/metabolism , Pregnancy , Rumen/analysis , Starch/administration & dosage , Zea maysABSTRACT
Dried distillers grains produced from a mix of 65% barley and 35% corn were evaluated in digestion and lactation experiments. Dried barley distillers grains had 56% NDF, 29% CP, 3% amino acid N, 2.5% NDIN (55% of total N), and 1.8% ADIN (39% of total N). Wet barley distillers grains had 38% NDF, 27% CP, 2.7% amino acid N, .5% NDIN (12% of total N), and .8% ADIN (19% of total N). Digestibility of DM and N was similar among lactating dairy cows fed diets containing approximately 25% corn silage DM, 15% alfalfa silage DM, 15% alfalfa hay DM, plus varying amounts of a corn-barley concentrate mix and supplemental CP from soybean meal, barley distillers grains, or from 1:1 mixture of soybean meal and barley distillers grains. Digestibility of ADIN, NDF, and ADF increased with increasing amounts of barley distillers grains in the diet. Similar diets were fed to 60 Holstein cows for 84 d in a lactation experiment. Source of supplemental protein did not affect milk production (22.5 kg/d), FCM (20.4 kg/d), milk fat percent (3.6%), or DM intake (19.0 kg/d). Milk protein percent was decreased by feeding barley distillers grains. It was concluded that barley distillers grains were an acceptable protein source for dairy cows and that ADIN and NDF might not be appropriate measures of the nutritional value of this product.
Subject(s)
Animal Feed , Cattle/physiology , Dietary Proteins/pharmacology , Edible Grain , Hordeum , Amino Acids/analysis , Animal Feed/analysis , Animals , Dietary Proteins/administration & dosage , Digestion , Female , Lactation , Nutritive Value , Pregnancy , Glycine max/analysis , Zea maysABSTRACT
Twenty Holstein heifers were assigned to either a control or test (stair-step compensatory; food restriction, followed by refeeding) growth group. The stair-step growth model was designed to induce distinctive compensatory allometric mammary development during three different hormonal states, coinciding with prepubertal, pubertal, and late gestational stages. Mammary tissues obtained by biopsy from pregnant and lactating cows were used for acini culture and chemical composition analysis. Test mammary tissues from late gestation heifers contained less (P = .067) fat than control counterparts (731 vs. 628 mg/g). DNA, RNA, and protein contents in test mammary tissue from late gestation cows were higher (P = .001 to .088) compared to control tissue. Milk protein secretion of test acini in culture was increased more than 20% over that of the control acini. Lactating mammary acinar cells in culture from test cows exhibited a 14% increase in amino acid uptake over that of the control. RNA dot-blot hybridization analysis revealed that alpha s1- and beta-casein mRNA accumulation in acini from test tissue was increased (P = .027 to .042) as much as 40-50%. During both food restriction and refeeding, concentrations of plasma growth hormone were elevated. Food restriction decreased levels of plasma insulin, whereas levels of insulin were elevated during refeeding. The long-term influence of compensatory growth upon subsequent lactation performance was also evaluated. Milk production data derived from previous two sequential growth trials showed that cows from test groups produced approximately 10% more (P = .001) milk compared to control counterparts. Results reinforce our postulation that compensatory growth induced by nutritional modulation regulates the differentiation and functional activity of the mammary gland.
Subject(s)
Growth , Lactation/physiology , Animal Nutritional Physiological Phenomena , Animals , Cattle , Cell Differentiation , DNA/analysis , Diet , Female , Growth Hormone/blood , Insulin/blood , Mammary Glands, Animal/analysis , Mammary Glands, Animal/cytology , Mammary Glands, Animal/drug effects , Mammary Glands, Animal/physiology , RNA/analysisABSTRACT
The primary objective of this study was to improve the productive efficiency of growth via optimal use of both high fiber-low quality and high energy-high protein feeds in diets for growing dairy cattle. Twenty Holstein heifers were randomly assigned to either a control or treatment group. The control diet met the National Research Council (NRC) requirement for .45 kg/d gain, with heifers calving at 24 to 26 mo of age. The test groups were fed according to a 5-2-5-2 mo schedule in which the nutrient density was alternately 15% below or 40% above the NRC requirement. Results showed that the heifers on the test dietary regimen (compensatory growth) gained more and consumed less, resulting in significantly improved efficiency of growth (body gain/dry matter intake X 100), energy (body gain X 1,000/metabolizable energy (ME) intake) and protein utilization (body gain/protein intake X 100) in comparison to control animals (13.0 vs 7.3%; 57.9 vs 32.6 g/Mcal ME; 96.5 vs 54.2%, respectively). Marked changes in average concentration of urea-N, glucose, triglycerides, cholesterol and lecithin cholesterol acyltransferase activity in blood were seen for test heifers during the stair-step growth phase (i.e., alternating maintenance and compensatory). Evidence from this experiment suggests that the phased growth (stair-step) system offers a simple, practical and cost-effective method for raising dairy heifers.
Subject(s)
Animal Feed , Animal Nutritional Physiological Phenomena , Body Weight/drug effects , Cattle/growth & development , Dietary Proteins/pharmacology , Animals , Female , Lactation/physiology , PregnancyABSTRACT
This study identifies and analyzes factors under a hospital's control that can affect its market share. The study, utilizing the Multiplicative Competitive Interaction model, specifically focuses on determining the market share for each hospital within a geographic area, as opposed to the total demand for hospital services within an area. The results indicate that the effect of the number of physician affiliations on hospital patient share is statistically significant. The article investigates the variables that affect the level of physician affiliation. Besides physician affiliation, hospital location, a PROFILE factor based on a composite of a number of variables, and the proportion of affiliated physicians who are not affiliated elsewhere have a significant impact on each hospital's market share. The variables examined resulted in an R2 = 0.901 for individual hospital patient market share.
Subject(s)
Health Services Needs and Demand , Health Services Research , Hospitals/statistics & numerical data , Marketing of Health Services , Models, Theoretical , Catchment Area, Health , Economic Competition , Humans , Medical Staff, Hospital , Organizational Affiliation , Pennsylvania , Public RelationsABSTRACT
Consideramos que este estudio de campo fue oportuno y pertinente. Nuestras observaciones son demasiado anticipadas para justificar conclusiones. En los próximos meses se dispondrá de nuevos datos. Los hallazgos obtenidos sólo se presentan a título de información sobre la marcha del trabajo realizado ya(AU)
Subject(s)
Epidemiological Monitoring/methods , Poliovirus Vaccine, Oral , Immunization Programs , Poliomyelitis/immunology , United StatesABSTRACT
1. El trabajo presenta los datos preliminares de un estudio de campo hecho en el condado de Dade, Florida, en que fueron vacunadas 412.000 personas con una sola dosis, administrada por vía oral, de vacuna antipoliomielítica trivalente Cox-Lederle de virus vivo atenuado
2. Se informa sobre los estudios de anticuerpos poliomielíticos neutralizadores en 594 individuos que carecían de anticuerpos de uno o más tipos de virus poliomielítico antes de la vacunación oral. La eficacia de la vacuna, medida por su capacidad de producir anticuerpos en estos individuos, fue la siguiente: 95 por ciento para el tipo 1, 97 por ciento para el tipo 3 y 78 por ciento para el tipo 2
3. Nuestra experiencia nos lleva a creer que los estudios de campo en gran escala de la vacuna antipoliomielítica de administración oral pueden y deben ser llevados a cabo en los grupos sociales y geográficos y grupos de edad en los cuales se proyecta, en definitiva, utilizar la vacuna(AU)
Subject(s)
Poliovirus Vaccine, Oral/therapy , Poliovirus Vaccine, Oral/administration & dosage , Poliovirus Vaccine, Inactivated/adverse effects , Poliomyelitis/epidemiology , Poliomyelitis/immunology , Follow-Up Studies , Health Surveys , United StatesABSTRACT
1. El trabajo presenta los datos preliminares de un estudio de campo hecho en el condado de Dade, Florida, en que fueron vacunadas 412.000 personas con una sola dosis, administrada por vía oral, de vacuna antipoliomielítica trivalente Cox-Lederle de virus vivo atenuado
2. Se informa sobre los estudios de anticuerpos poliomielíticos neutralizadores en 594 individuos que carecían de anticuerpos de uno o más tipos de virus poliomielítico antes de la vacunación oral. La eficacia de la vacuna, medida por su capacidad de producir anticuerpos en estos individuos, fue la siguiente: 95 por ciento para el tipo 1, 97 por ciento para el tipo 3 y 78 por ciento para el tipo 2
3. Nuestra experiencia nos lleva a creer que los estudios de campo en gran escala de la vacuna antipoliomielítica de administración oral pueden y deben ser llevados a cabo en los grupos sociales y geográficos y grupos de edad en los cuales se proyecta, en definitiva, utilizar la vacuna(AU)
Publicado en inglés en Scientific Publication 50:435-444, 1960
Subject(s)
Poliovirus Vaccine, Oral , Poliovirus Vaccine, Inactivated , Poliomyelitis , Follow-Up Studies , Health Surveys , United StatesABSTRACT
Consideramos que este estudio de campo fue oportuno y pertinente. Nuestras observaciones son demasiado anticipadas para justificar conclusiones. En los próximos meses se dispondrá de nuevos datos. Los hallazgos obtenidos sólo se presentan a título de información sobre la marcha del trabajo realizado ya(AU)
Publicado en inglés en Scientific Publication 50:445-456, 1960
