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Biomedical subjects

G R Frank

Publications and source records attributed to G R Frank.

At least 73 records · Page 4Linked to original sources
PubMed1984

Riboflavin requirement of gestating swine.

Forty crossbred gilts (9 to 10 mo of age) were used to determine the riboflavin requirement for gestating swine. Upon mating, gilts were assigned to one of five levels of dietary riboflavin (.77, 1.77, 2.77, 3.77 or 4.77 ppm) and individually fed 2.0 kg daily of the assigned diet throughout gestation. Gilts were bled on d 7, 24, 30, 35, 40, 56, 70, 84, 90 and 97 postcoitum. On d 1 postpartum, all sows and their live piglets were bled. Hemolysates of isolated, washed erythrocytes were prepared from blood samples and assayed to establish the erythrocyte glutathione reductase activity coefficient (EGRAC) as an indicator of the riboflavin status of each animal. The higher the EGRAC, the greater the severity of the riboflavin deficiency. During gestation, the EGRAC of gravid gilts increased with time in a manner dependent upon the level of dietary riboflavin. Postpartal EGRAC were elevated in dams fed the three lowest levels of dietary riboflavin during gestation. Of the six gravid gilts fed .77 ppm riboflavin, four gilts gave birth, approximately 7 d prematurely, to stillborn litters while two gilts failed to farrow by 121 d postcoitum. Litter weights at birth and gestation weight gains of these gilts were less than those of gilts fed the higher levels of riboflavin. Postnatal mortality of piglets was greater for those litters from sows fed 1.77 ppm riboflavin than for those from sows fed higher levels of riboflavin. The riboflavin status of newborn piglets was similar to that of their dams as determined by EGRAC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

A study of the relationship between performance and dietary component digestibilities by swine fed different levels of dietary fiber.

A 49-d feeding trial, using 192 growing-finishing pigs (avg initial wt, 32 kg), was conducted to identify pigs of widely differing average daily gains (ADG) when fed 16% crude protein diets containing either 0, 7.5 or 15% corn cobs. There were linear decreases in both ADG (P less than .01) and gain/feed (P less than .001) with increasing levels of dietary corn cobs. Average daily feed intake increased linearly (P less than .001), but average daily digestible energy (DE) intake tended to decrease (P less than .08) with increasing dietary fiber level. Gain/DE was not apparently affected by dietary treatment. At the end of the feeding trial, 27 pigs, nine from each dietary treatment, were selected on the basis of ADG to represent pigs of above average, average and below average performance during the feeding trial. Previous ADG of the pigs selected for these were .93, .81 and .69 kg, respectively. In these pigs, plasma levels of glucose decreased (P less than .01) linearly, but urea N tended to increase (P less than .08) linearly with increasing level of dietary corn cobs. A digestion trial was conducted to determine if previous performance of the selected pigs could be related to the digestibilities of dietary components and the retention of N by these pigs. Nitrogen and dry matter (DM) digestibilities and dietary DE decreased linearly with increasing level of dietary corn cobs. The digestibilities of dietary neutral detergent fiber (NDF) and acid detergent fiber (ADF) decreased both linearly and quadratically with increasing level of corn cobs. Regardless of dietary treatment, no significant differences in any of these criteria were observed among pigs selected on the basis of widely differing ADG during the feeding trial.

Animals↗
PubMed1982

Anthropomorphic breast phantoms for assessing ultrasonic imaging system performance and for training ultrasonographers: part I.

Three prototype anthropomorphic breast phantoms are discussed. The phantoms were constructed using ultrasonically tissue-mimicking materials; these materials mimic various tissue parenchymae in terms of attenuation, speed of sound, density, and scatter level. Realistic artifacts related to refraction and reflection at interfaces between different simulated parenchymae are produced. The phantoms represent premenopausal breasts, and they complement one another. Two of them represent the dense breasts of women under 30 years of age, and one represents that of a woman between 35 and 40 years of age. Of the former two, one produces what is apparently above-average refraction effects in the region of the peripheral fat layer; the other produces more typical refraction effects. Simulated tumors, cysts, and calcifications of various sizes are suspended in the glandular regions. Such phantoms are valuable for use in developmental testing of state-of-the-art ultrasound machines, quality assurance testing of clinical machines, and training of sonographers in breast imaging.

Adult↗
PubMed1982

Anthropomorphic breast phantoms for assessing ultrasonic imaging system performance and for training ultrasonographers: part II.

Three prototype anthropomorphic breast phantoms are discussed. The phantoms were constructed using ultrasonically tissue-mimicking materials; these materials mimic various tissue parenchymae in terms of attenuation, speed of sound, density, and scatter level. Realistic artifacts related to refraction and reflection at interfaces between different simulated parenchymae are produced. The phantoms represent premenopausal breasts, and they complement one another. Two of them represent the dense breasts of women under 30 years of age, and one represents that of a woman between 35 and 40 years of age. Of the former two, one produces what is apparently above-average refraction effects in the region of the peripheral fat layer; the other produces more typical refraction effects. Simulated tumors, cysts, and calcifications of various sizes are suspended in the glandular regions. Such phantoms are valuable for use in developmental testing of state-of-the-art ultrasound machines, quality assurance testing of clinical machines, and training of sonographers in breast imaging.

Adult↗
PubMed1982

Oil-in-gelatin dispersions for use as ultrasonically tissue-mimicking materials.

A form of tissue-mimicking material is reported in which oil droplets are dispersed in a water-based gelatin. Broad ranges of ultrasonic parameters, including speed of sound, attenuation coefficient, density and backscatter level, exist for this material. Very important, the attenuation coefficients are nearly proportional to the frequency as in the case of mammalian tissue and the available attenuation coefficient slopes span the range of mammalian tissues. The available range of slopes is 0.1 dB/cm/MHz through at least 2.0 dB/cm/MHz. The available speeds of sound range from a minimum below that of mammalian fat (approximately 1460 m/s) to a maximum above the accepted average for human tissue (154o m/s). Densities available range from below that of fat (approximately 0.92 gm/cm3) through about 1.00 gm/cm3. Backscatter levels are easily made negligible compared to clinical levels and compared to those exhibited in previously reported tissue-mimicking materials in which the suspended particles are solid (Madsen et al. 1978; Burlew et al., 1980). Addition of solid or hollow glass scatterers allows backscatter levels to be made comparable to those clinically observed.

Adipose Tissue↗
PubMed1982

An anthropomorphic ultrasound breast phantom containing intermediate-sized scatterers.

An anthropomorphic breast phantom, built from materials which mimic tissue parenchymae with respect to attenuation coefficients, speeds of sound, densities and backscatter levels, is described in detail. One of the outstanding features of the phantom is that 30% of the volume of the glandular region consists of tissue-mimicking fat, the remainder being tissue-mimicking glandular (non-adipose) tissue. The presence of these tissue-mimicking fat globules should cause ultrasound beam distortions similar to those found in clinical scans of the breasts of younger women. Halliwell (1977) has presented direct evidence for such beam distortions in real breasts. Other tissues simulated in the phantom are: skin, subcutaneous and retromammary fat, Cooper's ligaments, ducts and (abnormal)masses. The potential areas of usefulness of the phantom are: aiding in the development of more effective ultrasound imaging machines, discovering-- or verifying the causes of--various artifacts in breast imaging, routine testing of instruments being used clinically for breast imaging, and training of ultrasonographers. Ultrasound images of the phantom, made using three different instruments, are displayed and discussed.

Adipose Tissue↗
PubMed1981

A technique for monitoring nutrient absorption in the conscious, unrestrained pig.

A surgical preparation allowing for the determination of apparent absorption in the conscious, unrestrained pig is described. The technique allows the collection of blood from the hepatic portal vein and vena cava, as well as the simultaneous determination of rate of flow through the portal vessel. A chronic electromagnetic blood flow probe is placed around, and a mechanical, hydraulically activated sampling needle attached to, the hepatic portal vein. An indwelling catheter is placed within the vena cava. By simultaneously determining nutrient concentration of hepatic portal and vena cava blood and then multiplying their difference by the rate of blood flow through the hepatic portal vein, one can make a point-in-time estimate of apparent absorption from the gastrointestinal tract.

Absorption↗
PubMedDate not supplied

Tissue-mimicking gelatin-agar gels for use in magnetic resonance imaging phantoms.

A new variety of tissue-mimicking materials for use in 1H nuclear magnetic resonance (NMR) phantoms has been developed and extensively tested, principally at 10 MHz and at room temperature. The materials can be formed with a broad range of T1's and T2's representative of soft tissues. They are mixtures of various percentages of agar, animal hide gelatin, water, and glycerol. Small concentrations of formaldehyde and n-propanol prevent melting through 100 degrees C and prevent bacterial invasion. The materials are easily produced. A thorough description of compositions and production procedures is given. T1's exhibit about a 5%/degrees C rise in temperature. T2's exhibit less than a 1% rise/degrees C. Long-term (12 months) stability is exhibited both for NMR properties and for absence of fluid extrusion. Preliminary results indicate that T1's depend on the Larmor frequency in a similar way to that observed in soft tissues.

Agar↗
PubMedDate not supplied

A reusable perfusion supporting tissue-mimicking material for ultrasound hyperthermia phantoms.

A new ultrasonically and thermodynamically tissue-mimicking material is reported. The material is well suited for use in phantoms for testing ultrasound hyperthermia systems or related predictive models. Controlled convective heat transfer effects, mimicking to some extent perfusive heat transfer in tissues, can be instituted in the material with appropriate fluid sources and sinks. The material consists of closely packed agar spheres varying in diameters from 0.3-3.6 mm. The interstitial space between spheres is filled with 10% n-propanol solution. The material has two practical advantages over the solid-gel-type tissue-mimicking materials. The first advantage is that it allows rapid return of a hyperthermia phantom to thermal equilibrium following a heating test by rapid circulation of the perfusion fluid. The second advantage is that the material is in a "liquid" form. It can be easily siphoned in and out of phantom containers of any geometric shape for different purposes without change in its physical properties. Methods for measuring ultrasonic and thermodynamic properties of the material and the results of the measurements are reported. The physical parameters measured are the intensity attenuation and absorption coefficients, the ultrasonic speed, the thermal conductivity, specific-heat capacity and the mass density. Temperature measurements in a hyperthermia phantom made of the material are also reported.

1-Propanol↗