A comparison of the enzyme levels and the in vitro utilization of various substrates for lipogenesis in pair-fed lean and obese pigs

In this study of spontaneous obesity of pigs, specific metabolic shifts were observed, which explain an increase in fat deposition. Liver tissue utilization of pyruvate and glucose for oxidation and lipogenesis showed no significant difference between lean and obese pigs. Adipose tissue utilization of glucose, acetate and glycerol for triglyceride and fatty acid synthesis was greater in obese pigs than lean pigs (P less than 0.01). No significant difference in leucine incorporation into lipid fractions was found. Of the substrates utilized, glucose supplied 86 and 94% of the glyceride-glycerol synthesized in lean and obese pigs, respectively. Glycerol was not a major contributor to glyceride-glycerol synthesis (3.5 to 5.5%), in spite of the presence of adipose tissue glycerokinase. An increase (P less than 0.05) in alanine incorporation into glucose was observed in liver tissue from obese pigs. In general, the levels of enzymes activities associated with gluconeogenesis, glycolysis, and lipogenesis supported the findings of in vitro utilization of these substrates.

Brucella infections in Illinois veterinarians

Serums collected from Illinois veterinarians at 6 state conventions between 1956 and 1972 were tested for Brucella antibodies, with 70 of 394 (17.8%) samples reactive. Interviews with 1,261 veterinarians in 1967 and 1968 yielded 175 (13.9%) with a history of a prior clinical illness diagnosed as brucellosis. When duplicates were eliminated, there was a 17.0% (224/1,315) infection ratio. The prevalence of infection was found to be decreasing, as reflected by decreasing serologic reactor rates and by decreasing numbers of clinical diagnoses during the period. Strain 19 brucella vaccine appeared to be increasing in relative importance as a source of infection for veterinarians. Most of the small animal practitioners with a history of clinical brucellosis had been infected either as students or in an earlier practice type. Onset of clinical illness occurred the year of graduation for 21 (13%) veterinarians, with 62% between 4 years before and 4 years after graduation. Part of the explanation for the decreasing infection rates following graduation might have been the existence of a group of veterinarians at high risk of infection because of personal habits. Early infection, because of their high risk, would have resulted in rapid depletion of susceptible individuals from this group. As a result, in a few years the infection rate of the total veterinary population would no longer be dominated by this high risk group but would more nearly reflect the infection probability for the average veterinarian. There was no significant difference in death rates or cause of death between infected and noninfected veterinarians.

Effects of exercise and of food restriction on the development of spontaneous obesity in rats

The effects of exercise and of food restriction on Zucker obese and lean rats were studied. Zucker obese rats pair-fed to lean littermates gained more body fat on the same intake indicating greater efficiency of diet utilization. Exercise significantly reduced the fat pad weights and body fat content of obese rats. Serum insulin levels were higher in the obese rats and were not influenced by exercise. Exercise had no effect on adipose cellularity of the obese rats. Liver tissue in vitro lipogenic capacity and lipogenic enzyme activities were significantly elevated in obese rats. Exercise increased liver tissue hexokinase and in vitro lipogenesis in lean rats. Exercise increased pentose phosphate pathway enzymes in adipose tissue from lean rats only. Although exercise reduced fat content significantly, obese rats were still fatter (27.7% fat) than the lean controls (6.4% fat). The protein content of obese rats was significantly increased by exercise, indicating that physical activity is important in the regulation of protein metabolism.

Early development of adipose cell lipogenesis and glycerol utilization in Zucker obese rats

A study of adipose cell metabolism was made at ages 5, 7, 10, and 14 wk of age in genetically obese Zucker rats. Adipose samples were surgically removed and used for in vitro adipose cell incubations and for characterization of enzyme patterns. Lipogenic capacity from glucose and enzymes normally associated with lipogenesis (malic enzyme, citrate cleavage enzyme and glucose-6-PO4 dehydrogenase) followed the same pattern of development. At 5 wk of age, the adipose cells of obese animals had a greater capacity for fat synthesis than the lean rats. At all other ages lipogenic activity and enzyme levels were either similar or less than the pair-fed lean littermates. Glycerol utilization by isolated fat cells was similar; however, adipose tissue glycerokinase was elevated in obese rats at 14 wk of age. It was concluded that there was no apparent change in specific lipogenic capacity of fat cells from the obese rat when compared to its lean littermate. It was also concluded that increased adipose glycerokinase activity in obese rats represented a secondary shift in metabolism.

Cellular characteristics of skeletal muscle in selected strains of pigs and mice and the unselected controls

Skeletal muscle growth of swine differing in rate of growth and muscularity was studied by analysis of DNA, RNA, and protein in the semitendinosus muscle of fast growing domestic lean pigs (Yorkshire) and the slow-growing feral obese pigs (Ossabaw). Both lean and obese strains were fed ad libitum corn and soybean mean diet containing 14% protein. The pigs were slaughtered at 6 months of age. The Yorkshire pig had significantly greater body and muscle weights (P less than 0.005) Total DNA, RNA, and protein in semitendinosus muscles were significantly greater in the Yorkshire pigs (P less than 0.005). RNA/DNA and protein/DNA ratios were significantly different between the Yorkshire and Ossabaw pigs. These data suggest that the greater muscle growth in the Yorkshire pigs is achieved by greater cell numbers and size. The response of skeletal muscle cells and fiber characteristics to selection was studied in two strains of mice by analysis of DNA, RNA, and histological measurement of muscle fibers. Both strains were fed ad libitum on laboratory rat chow diet. They were sacrificed at 12 months of age. Leg muscle DNA and RNA were significantly greater in the mice selected for rapid growth rate as compared to the control (P less than 0.005 and P less than .10, respectively). Measurements of the semimembranosus muscle reveal that the growth strain had significantly greater muscle weight (P less than .01) and muscle length (P less than 0.005). Histological measurements of the same muscle showed that the growth strain had significantly greater fiber number (P less than 0.005) and larger fiber size (P less than 0.005) than the controls. It would appear that the greater muscle cellularity (DNA) in growth strain mice is accompanied by greater muscle length, fiber number, and fiber diameter.

Formation of light-guiding interconnections in an integrated optical circuit by composite tapered-film coupling

We demonstrate a new and simple method of forming light-guiding interconnections in an integrated optical circuit. This involves bridging the devices with a thin film having tapered ends that form naturally during the deposition process. Experiments show that there is no specific requirement for the thickness, refractive index, or relative position of the bridging film. A theory of composite waveguides provides an understanding of these interconnections.

Thin organosilicon films for integrated optics

The continued development of integrated optics is heavily dependent upon the availability of materials that are suitable for the construction of thin-film optical circuitry and devices. We report here an investigation of new films made by an rf discharge polymerization process of organic chemical monomers. We concentrate our discussion on films prepared from vinyltrimethylsilane and hexamethyldisilbxane. These films are smooth, tough, pinhole-free, transparent from 0.4 microm to 0.75 microm, and exhibit very low loss (<0.04 dB/cm) for light-wave propagation. More importantly, experiments demonstrate the possibility of controlling the refractive index of the films either by the mixing of the two monomers before deposition or by chemical treatment after the film is deposited. The use of the prism-film coupler for studying the refractive index of each material is discussed in detail.

Geometrical optics in thin film light guides

We consider thin film light guides consisting of a transparent film of high refractive index deposited on a substrate of lower index. The propagation of light in such a two-dimensional transmission medium can be described within the limits of geometrical optics by an effective index of refraction N. Its value depends on the film thickness. Therefore, a light beam in the thin film guide is refracted or totally reflected at a step of film thickness. We discuss these phenomena (Snell's law) and demonstrate them experimentally, using ZnS films on glass as guides. As applications, we show a thin film prism and thin film lenses for guided light beams. By properly choosing the film thicknesses at both sides of the step, one can obtain an unusually large positive or negative wavelength dispersion of the refraction or, if desired, achromatic refraction.

Optical propagation in sheet and pattern generated films of ta(2)o(5)

Attention is drawn to the properties of Ta(2)O(5) film which make it attractive as a new dielectric medium for use in integrated optical circuitry. The Ta(2)O(5) film discussed was formed by thermally oxidizing sputtered , beta-tantalum films in an oxygen atmosphere. Measurements showed that these films will support propagation of coherent red (6328-A.) light with a loss of 0.9 dB cm(-1) and coherent blue (4880-A) light with a somewhat higher loss of 4.1 dB cm(-1). From measurements of the coupling angle at which propagation of the various modes takes place, refractive indices for the TE and TM modes at 6328 A, 5145 A, and 4880 A were obtained. The loss mechanisms are discussed, and it is shown that most of the loss is due to scattering during the internal reflections at the air-oxide and oxide-substrate film surfaces. A small fraction of the loss appears to occur in the interior of the film. With Ta(2)O(5) it is demonstrated for the first time that optical circuit components can be formed for use in integrated optics by employing existing thin-film technology. The basic process steps include the pattern generation of the beta-Ta followed by thermal oxidation of the pattern. Experimental studies of propagation in straight and curved waveguides are described. It was found that the losses in pattern generated waveguides are of the order of 5 dB cm(-1) to 7 dB cm(-1), with the excess loss due to scattering from the waveguide edges. It is concluded that improvements in the smoothness of the boundaries of circuit elements are desirable to reduce transmission losses in pattern generated film.