Measurement and partial characterization of immunoreactive glucagon in gastrointestinal tissues of dogs

We have reported previously that increasing amounts of immunoreactive glucagon (IRG), measured by four specific antisera, appeared in plasma of depancreatized insulin-deficient dogs. It was therefore concluded that pancreatectomy was not accompanied by glucagon deficiency in the dog, but instead excessive amounts of extrapancreatic IRG could contribute to the diabetic syndrome. In order to locate the source of extrapancreatic glucagon, tissue extracts were assayed with anti-glucagon sera 30-K and K-44, which cross-react minimally with crude gut extracts. IRG was detected in all gastrointestinal tissues and in the salivary glands, but not in extracts of liver, kidney, brain, heart atrium, and adenohypophysis. Immunologic dilution curves of extracts from all gastrointestinal tissues were parallel to those of the pure pancreatic glucagon standard, and both antisera (30-K and K-44) measured the same concentrations. The highest concentration of gastrointestinal IRG was found in the fundus and corpus of the stomach. Presence of IRG in gastrointestinal tissues of depancreatized dogs indicates that gastrointestinal cells can not only secrete but also store large amounts of IRG. Extracts of mucosa of stomach fundus were further purified by gel filtration on Biogel P-30 columns. The immunoreactivity in the eluate was assayed by 30-K and a strongly crossreacting antibody, K-4023. One pooled fraction corresponding to marker pancreatic glucagon in its elution volume was found to contain the largest amount of IRG and the highest specific immunoreactivity (IRG/protein concentration). This fraction showed also the highest activity in a glucagon-receptor assay system. Disc gel electrophoresis in the presence of urea resolved this fraction into three immunoreactive components, one of which was identical to pancreatic glucagon in its electrophoretic mobility. It appears, therefore, that mucosa of the upper stomach in the dog contains a polypeptide similar to pancreatic glucagon. We conclude that (a) hyperglucagonemia in the dog can result from excessive secretion of IRG not only by the pancreatic alpha cells but also by cells of the gastrointestinal tract; (b) the highest IRG concentration was found in fundus and corpus of the stomach and lower concentrations throughout the gastrointestinal tract; (c) the IRG component in the stomach displayed immunologic and physical properties similar to pancreatic glucagon.

Comparison of non-screen techniques (medical vs. industrial film) for fine-detail skeletal radiography

High resolution radiographic techniques for imaging the peripheral skeleton (hand and foot) have gained wide clinical acceptance. The two procedures receiving widest attention are non-screen techniques: one uses medical film (Kodak RP); and the other uses industrial film (Kodak Type M) combined with optical magnification. The imaging properties and clinical applications of these two techniques were examined. The modulation transfer functions (MTF's) of the recording systems, Wiener spectrum analyses of noise, and film sensitometry were obtained. Clinical comparisons were made from 200 consecutive patients radiographed with both techniques and the relative merits in metabolic, arthritic and traumatic afflictions were assessed. The results demonstrate the superiority of the industrial film compared to medical film technique in all parameters of image quality. However, the inconveniences of special processing and viewing necessitated by this technique, as well as the increased radiation exposure, limit its clinical application to small, selection groups of patients as determined from the clinical comparative study.

Seasonal variation of urinary excretion of total metanephrines

Results of 1414 measurements of urinary excretion of free and conjugated (total) metanephrine and normetanephrine (total metanephrines, tMN) and of 1630 measurements of vanilmandelic acid (VMA) excretion were analysed according to the month of sample collection. These collections had been carried out as a part of a study of hypertension at out institute over the 5-year period between 1970 and 1975. The means and scatters of tMN were significantly varied depending on the season of the year; the mean during 3 months of summer was 380 mug/day and the mean for 3 winter months 800 mug/day. The scatter of tMN in winter months was wider. A minor seasonal variation was observed for VMA: the means of summer and winter months were 3.8 mg/day and 4.5 mg/day, respectively. The results suggest a seasonal difference of catecholamine catabolism.

Is glucagon involved in cold acclimatization?

Cold acclimatization in rats at 5 degrees C for 2 weeks caused a significant elevation of plasma glucagon concentration, accompanied by increased plasma FFA and glucose levels. Acute cold exposure at 5 degrees C for 5 or 60 min did not affect these parameters in plasma.

The influence of thyroxine on the serum free triiodothyronine concentration

By means of measurement of the serum free triiodothyronine fraction (%FT3) by equilibrium dialysis, the influence of varying serum concentrations of thyroxine (T4) on %FT3 was studied in conditions associated with lack or excess of serum T4 and in serum enrichment with T4 in vitro. The enrichment of pooled serum with T4 caused significant increases of %FT3 with T4 was added to elevate its T4 content between 10 and 25 mug/dl. In 4 subjects with primary hypothyroidism treated with T3 (25 mug once daily for two weeks, twice daily thereafter), progressive increases of serum T3 were observed while their T4, free T4 and T3 fractions remained unchanged. Consequently, the serum free T3 and thyrotropin concentrations became normal after the serum T3 concentrations became hypernormal. When comparisons of the serum thyroid hormone levels were made between 6 subjects with T3 toxicosis and 8 with a usual variety of hyperthyroidism matched for serum T3 concentration, the former sub-group of hyperthyroidism showed significantly lower serum free T3 concentration (0-51 +/- 0.22 ng/dl versus 0.79 +/- 0-21 ng/dl, p less than 0.05). The amount of T4 in serum is considered to affect its free T3 concentration by virtue of sharing serum-binding proteins.

Comparison of image quality obtained with optical and radiographic magnification techniques in fine-detail skeletal radiography: effect of object thickness

High-resolution radiography may be done using either optical or radiographic magnification. In the former technique, industrial Type M film was used without screens and the image was viewed with 4-10X optical magnification. In the latter technique, RP film was used with Detail screens and 4X geometric magnification together with a microfocus x-ray tube having a nominal focal spot size of 50 mum. The imaging properties of both techniques were evaluated by means of H & D curves, modulation transfer functions, and Wiener spectra. It was found that for thin objects such as the hand, optical magnification provides better bone images than radiographic magnification; whereas for thicker parts such as the knee, radiographic magnification is superior.

Effects of diets on cold tolerance and metabolic responses to cold in fasted rats

Effects of high-fat and high-protein diets on cold tolerance in fasted rats were investigated. High-fat diets caused significant increases in body weight, blood-free fatty acids (FFA), ketone bodies and glucose, while high-protein diet did not modify any of these parameters. Rats on high-fat diets that were exposed to cold after clipping exhibited an intermediate cold tolerance as assessed by the rate of fall in colonic temperature between control rats on a standard diet and cold-acclimated rats. The extent of increase of blood FFA and decrease of blood glucose due to cold exposure was less in the high-fat diet group than in control group, but greater than in cold-acclimated group. The lower fall in colonic temperature due to cold exposure was signifcantly associated with less increase in blood FFA and less decrease in blood glucose. In this relation the high-fat diet group was also intermediate between the control and cold-acclimated groups. The high-protein diet did not make any difference in cold tolerance and cold-induced changes in blood metabolites as compared with those in control standard diet, although it resulted in a marked increase in urinary nitrogen excretion. These results indicate that a high-fat diet could exert a significant favorable effect on cold tolerance in fasted rats, but the effect would not be as much as as in cold acclimated rats.

X-ray images of small blood vessels in angiography: question of isoplanatism

The basic theory of x-ray image formation of blood vessels, which is related to isoplanatism, is discussed. The x-ray intensity distributions of the blood vessel images are derived first for the actual case, which gives "correct" x-ray images obtained by the ray-tracing method. Secondly, as an approximation of the actual case, the image distributions are derived by the convolution method, which corresponds to an isoplanatic case. It is concluded that, under practical conditions, x-ray images of blood vessels are given approximately by a convolution integral of the object distribution, that is, the input x-ray pattern of the vessel exposed with a parallel x-ray beam, with the line spread function of geometric unsharpness. Therefore, this theory provides support for the experimental procedure commonly used in obtaining blood vessel images, and for the validity of applying in angiography the concept of the line spread function and the modulation transfer function of geometric unsharpness.

New device for accurate measurement of the x-ray intensity distribution of x-ray tube focal spots

A new device has been developed with which the focal spot distribution can be measured accurately. The alignment and localization of the focal spot relative to the device are accomplished by adjustment of three micrometer screws in three orthogonal directions and by comparison of red reference light spots with green fluorescent pinhole images at five locations. The standard deviations for evaluating the reproducibility of the adjustments in the horizontal and vertical directions were 0.2 and 0.5 mm, respectively. Measurements were made of the pinhole images as well as of the line-spread functions (LSFs) and modulation transfer functions (MTFs) for an x-ray tube with focal spots of 1-mm and 50-mum nominal size. The standard deviations for the LSF and MTF of the 1-mm focal spot were 0.017 and 0.010, respectively.

[Studies on the mechanism of the diabetogenic activity of streptozotocin and on the ability of compounds to block the diabetogenic activity of streptozotocin (author's transl)]

The present study was undertaken to clarify the mechanism of the diabetogenic activity of streptozotocin. Experiments were conducted to determine the resistance of animals to the diabetogenic action of streptozotocin; to follow the time course of irreversible beta-cell damage, and to determine the influence on streptozotocin action of certain compounds. Streptozotocin, a broad spectrum antibiotic, with antitumoral properties, was shown to be diabetogenic in rats and mice, but not in cats, rabbits, or guinea pigs. Intravenous or intraperitoneal administration of 65 mg/kg body weight of streptozotocin to male Wistar rats evoked a tri-phasic blood sugar response. It induced an initial hyperglycemic peak with no apparent change in plasma insulin concentrations, followed by profound hypoglycemia caused by liberation of large amounts of insulin from the pancreas. Forty-eight hours after injection, the animals were completely diabetic. Light- and electron-microscopic exadminations during the first forty-eight hours after the injection of streptozotocin showed pyknosis, degranulation and marked degeneration of the beta-cells. 1egenerative and necrotic changes were also seen in a few alpha-cells. These streptozotocin-induced diabetic rats revealed polydipsia, polyuria, polyphagia and glucosuria, and decreased body weight. Blood sugar, plasma FFA and insulin concentrations were examined after oral administration of glucose (OGTT: 3g/kg). Blood sugar and plasma FFA were significantly elevated but plasma insulin concentrations were markedly decreased, so insulin treatments were most effective in these animals. It has been reported that nicotinamide prevents the diabetogenic activity of streptozotocin and the deformity action of 6-aminonicotinamide and 3-acetylpridine. Pre-treatment with picolinamide, methyl-nicotinamide, and nicotinohydroxamic acid also blocked its diabetogenic action, but nicotinic acid, mannoheptulose and glucose were ineffective. N-nitrosodimethylamin and ethyl-N-nitrosomethylcarbamate were devoid of diabetogenicity. It seems that streptozotocin interfers with NAD formation in the beta-cell. Functioning pancreatic islets cell tumors were observed on the rats both at 407 days after streptozotocin administration and at 473 days after streptozotocin administration with nicotinamide (500 mg/kg, i.p.).

Optical versus radiographic magnification for fine-detail skeletal radiography

Fine-detail radiographic techniques for peripheral skeletal imaging have gained wide clinical acceptance. In this study, the imaging properties and clinical applications of the optical magnification technique, which employs fine-grain industrial film and a large focal spot, are compared quantitatively and qualitatively with those of three slow screen-film techniques, namely, contact exposure with a large focal spot, 2 times radiographic magnification with a 0.3 mm focal spot, and 4 times radiographic magnification with a 50 mu focal spot. The modulation transfer functions (MTF's) of the recording systems and focal spots are obtained and film sensitometry performed. Clinical comparisons are made for patients with metabolic, arthritic, and neoplastic skeletal disorders. The results illustrate the superiority of the optical magnification technique over contact or 2 times magnification techniques using slow screen-film systems. If a microfocus tube is used, however, direct radiographic magnification may provide images comparable in resolution, noise and contrast to those made with the optical magnification technique, and at lower radiation exposure to the patient.

[Simultaneous measurements of free thyroxine and triiodothyronine fractions in human serum by means of equilibrium dialysis (author's transl)]

Simultaneous measurements of serum free thyroxine (T4) and triiodothyronine (T3) fractions were studied using a modification of equilibrium dialysis described by Sterling and Brenner. To 1.2 ml of the serum to be assayed, 131I-T4 and 125I-T3 were added in a concentration of 2 mug/dl and 25 ng/dl, respectively, both of which were preliminarily dialysed according to Schussler and Plager. Half ml of the serum with tracers added was dialysed against 9 ml of phosphate buffer (ionic strength 0.15, pH 7.4) for 18 hours at 37 degrees C and 0.1 ml was reserved from the rest in a counting tube (in duplicate). After the completion of dialysis, the dialysate was mixed with 1 ml of pool serum and the contaminating inorganic iodide (in the form of 131I or 125I) was eliminated by adsorption on anion exchange resin. The radioactivity of 3 ml of the dialysate and 0.1 ml of the preserved serum (with the tracers added) was counted and the free (or dialysable) fractions were expressed as a ratio of the count of the former divided by that of the latter adjusted to an equal volume by calculation. The amount of either T4 or T3 added as tracers had no influence on free T4 or T3 fraction unless either of them was added to a concentration of 10 mug/dl. When 125I-T3 of low specific activity (50 muCi/ug) was used as a tracer, free T3 fraction measured simultaneously with free T4 fraction tended to be higher than that measured with a single tracer. When 125I-T3 of higher specific activity (300 muCi/mug) was employed, free T3 fraction obtained with two methods did not differ significantly. Using serum T4 and T3 concentrations measured by competitive protein binding analysis and radioimmunoassay, respectively, the free T4 and T3 concentrations were estimated with sera of normal, hyperthyroid, hypothyroid and uncomplicated pregnant subjects.

Effect of focal spot distribution on blood vessel imaging in magnification radiography

From a computer simulation study of blood vessel imaging with uniform, triangular, gaussian, and twin gaussian line spread functions (LSF) corresponding to various focal spot distributions, it is found that vessel images magnified less than 6 times are not strongly dependent upon the focal spot distributions when the size of the focal spot is equal to or smaller than the vessel diameter. When the focal spot is larger than the vessel, image distributions vary appreciably with focal spot distributions, except at low magnification. It is concluded that, in many practical cases, the focal spot distribution does not seriously affect magnified image distributions of blood vessels.

Longitudinal magnification in radiologic images of thick objects: a new concept in magnification radiography

New concepts which are useful for evaluating image resolution and distortion in magnification radiography are introduced. It is shown theoretically and experimentally that "longitudinal magnification" defined as the ratio of the magnified image size to the conventional image size for objects located in a plane perpendicular to the film, is given approximately by the square of the conventional magnification. Resolution in the radiographically magnified image of such objects is much higher than that obtained by optical magnification. This is confirmed experimentally by radiographs of square-wave test objects. The related image distortion is also discussed.

Effect of film graininess and geometric unsharpness on image quality in fine-detail skeletal radiography

Three direct x-ray films and three geometric conditions were used to study the effect of noise and sharpness on high resolution radiography of the hand. The Wiener spectrum of film graininess and the MTF of geometric unsharpness were measured. Radiographs of a wire mesh and a hand phantom, together with the Wiener spectra and MTFs, led to the following conclusions regarding fine-detail skeletal radiography, as currently employed: 1) bone structure detectable in vivo does not show minute structural detail; 2) the technique is primarily noise-limited; 3) the use of better geometry or finer grain film for improving resolution or noise is of limited practical value, whereas the use of poorer geometry or more noisy film results in appreciable degradation of skeletal images; and 4) the present standard technique for in vivo radiography of the hand, therefore, may be very nearly optimal for clinical applications.

The effect of geometric and recording system unsharpness in mammography

Modulation transfer functions (MTFs) and test object radiographs were used to study the effect of geometric and recording system unsharpness in mammography with the CGR Senographe x-ray unit. Results show that geometric unsharpness can be a significant factor in the detection of microcalcifications within the breast, depending on the size and shape of the focal spot, the focal spot-to-recording system distance, and the object-to-recording system distance (o.r.d.). A new recording system for mammography, the DuPont Lo-dose system, requires approximately 1/15th the exposure of a direct x-ray film, such as Kodak RP/M, to provide mammograms with comparable photographic density. With the Lo-dose system, geometric unsharpness can be reduced by use of a specially designed long cone with an increased focal spot-to-recording system distance. This cannot be accomplished with direct x-ray films because the x-ray unit is operating at near-maximum output conditions even when short cones are used. Although direct x-ray films have a higher resolution than the Lo-dose system, at certain o.r.d.s total resolution is found to be affected more significantly by geometric unsharpness than by the Lo-dose recording system. In several cases, clinical results show improved detection of microcalcifications at larger o.r.d.s by the Lo-dose system with a long one, combined with a reduction by a factor of 15 in patient exposure.

In vivo lipolytic effect of glucagon in warm-adapted and cold-adapted rats

In vivo effect of glucagon on blood-free fatty acid (FFA) concentration was investigated in rats adapted to 25 degree C and to 5 degree C. Intraperitoneal injection of glucagon in 100 or 25 mug/100 g body weight doses was followed by a triphasic response in blood FFA concentration: an immediate and marked rise at 5 min, a secondary depression at 60 min and a final rise at 120 to 240 min after the injectionss. For the 12.5 and 6.25 mug/100 g body weight injections, an initial increment was significantly lowered and no elevation at 240 min was observed. Concomitant elevations of blood glucose concentration were shown 5 min after glucagon injection of 100, 25, 12.5, and 6.25 mug/100 g body weight doses and their extents were not significantly different each other between these doses. However, rise in blood glucose level at 60 min was not seen at the 12.5 and 6.25 mug/100 g body weight doses. Blood lactate concentrations did not show any significant variations by the injections of glucagon. In fasting rats, glucagon at the 100 mug/100 g body weight dose caused similar increase in blood FFA as that in fed ones. In fed cold-adapted rats at 5 degree C glucagon at the dose of 100 mug/100 g body weight brought about similar effects in elevation of blood FFA level and its time-course as those in fed rats adapted to 25 degree C. However, under fasting condition cold-adapted animals exhibited greater increment in blood FFA level at 5 min than those adapted to 25 degree C, while an elevation of blood FFA at 240 min was not observed in the former animals. These results indicate for the first time an in vivo lipolytic action of glucagon in rats and further suggest an enhanced sensitivity to lipolytic action of glucagon in cold adaptation.

Cyclical effects of triiodothyronine on blood-free fatty acid and glucose concentrations in warm-adapted and cold-adapted rats

Effects of triiodothyronine (T3) (100 mug/100 g, sc) on blood-free fatty acid (FFA) and glucose concentrations were investigated in warm- and cold-adapted rats. Blood specimens were obtained from the tail locally anesthetized with lidocaine. In warm-adapted rats FFA rose 3 to 6 hr after administration of T3, but returned to the pre-injection level 12 hr later. Thereafter, blood FFA level showed a repeated cyclical rise and fall every 12 hr for up to 60 hr, while blood glucose level did not increase until 12 hr later and this level was maintained for up to 36 hr. After that time it also showed a repeated rise and fall every 12 hr for up to 60 hr. Both FFA and glucose levels returned to the initial values after 72 hr. Changes induced by T3 in blood levels of these metabolites were reciprocal. In cold-adapted rats the patterns of responses to T3 were essentially the same as those observed in warm-adapted ones, except that T3 provoked a simultaneous rise in blood glucose as well as FFA 6 hr after injection, although an extent of FFA increment was less than in warm-adapted rats. Reserpine pre-treatment caused a considerable reduction in the FFA mobilizing action of T3. The FFA and glucose mobilizing action of T3 was also observed at dosages of 25 and 6.25 mug/100 g, although to lesser extent. These results indicated for the first time the cyclical action of T3 on blood FFA and glucose concentrations, and a changed sensitivity to T3 in cold-adapted animals.