An experimental method of determining relative phase-contrast factor for x-ray imaging systems

The relative phase-contrast factor (RPF) represents a quantitative measure of the phase-contrast transfer in x-ray in-line phase-contrast imaging. The larger the modulus of RPF(u, v) is, the more the phase-contrast manifests. In this work we show how the RPF can be determined by measurements of the focal spot size and x-ray spectra for a x-ray imaging system with a micro-focus x-ray tube. The results show the significant effects of x-ray beam hardening on the visibility of phase-contrast, and reveal a new dimension in seeking optimal techniques for x-ray phase-contrast imaging.     

An experimental study of gastrointestinal motility during chronic large bowel obstruction]

Gastrointestinal motility and plasma PYY levels were investigated under chronic progressive large bowel obstruction in dogs. The obstruction device was applied around the descending colon at a laparotomy and gastrointestinal motility was recorded with strain gauge force transducers in the conscious state. Complete obstruction occurred at 26 days (21-33 days). The duration of postprandial interruption of motor complex (DIMC) in the antrum and duodenum were prolonged progressively, at partial obstruction (17.7 +/- 2.7 hr; p less than 0.05) and complete obstruction (23.0 +/- 4.0 hr; p less than 0.01) vs in control (13.7 +/- 1.9 hr), while DIMC in the small bowel showed no significant changes. Progressive obstruction caused hypermotility in the proximal colon to the obstruction and hypomotility in the distal colon. These dysmotility were improved after resection of the obstructed segment and anastomosis. Plasma PYY levels in the fasting state showed no significant increase at complete obstruction (42.6 +/- 14.5 pmol/l) vs in control (32.9 +/- 10.2 pmol/l).     

An evaluation of the Guest method for determining erythrocyte sedimentation rate

The Guest method for determining erythrocyte sedimentation rate was compared with the standard Westergren method. The Guest method consists of disposable plastic tubes with a method of filling with potentially infectious blood to avoid contact between the technician and the sample. Erythrocyte sedimentation rates were determined for samples containing normal and elevated fibrinogen levels. On the basis of the results of this study, the Guest method performed as well as the Westergren method in the population of healthy volunteers with normal fibrinogen levels and in the population of diseased individuals whose serum fibrinogen levels were elevated.     

An unique method for determining the permeability of the mitochondrial outer membrane

Mitochondrial function depends on the metabolite fluxes through the mitochondrial outer membrane. To directly measure the permeability of the outer membrane by using traditional methods is difficult due to the small volume of the intermembrane space and high permeability of the outer membrane. A method was developed to measure the permeability of the mitochondrial outer membrane by taking advantage of mitochondrial processes that consume the substrate being examined. A steady state concentration of substrate forms in the intermembrane space when the flux through the outer membrane equals the rate of substrate consumption. Thus, the rate of consumption of substrate depends on both processes and the extent of the contribution of each was sorted out by fitting to a steady-state theory. This report focuses on mitochondrial ATP phosphorylation and the determination of the permeability of the outer membrane to ADP. This approach also yields the intermembrane space [ADP] and shows how it differs from the extramitochondrial concentration.     

Effects of motility on epithelial transport in the human descending duodenum

The aim of the study was to determine how motility affects the balance between absorptive and secretory ion transport in the proximal human small intestine. Thirty‐two healthy subjects and 16 patients (eight with villus atrophy, eight with normal duodenal biopsies) were studied. The absorptive sodium flux was estimated by measurement of bicarbonate absorption with a double‐lumen perfusion technique. The secretory chloride flux was calculated from the ratio between the continuously recorded transmural potential difference (PD) and the epithelial parallel resistance, which was measured in forceps biopsies by square‐wave current analysis. Graded variations in contraction frequency were obtained by recording during defined time periods before, during and after phase III of the migrating motor complex (MMC). Bicarbonate was absorbed by a process that led to CO₂ formation, and both bicarbonate absorption and luminal P_CO2 increased with contraction frequency. The motility‐related P_CO2 rise was reduced in patients with villus atrophy and by removal of bicarbonate from the perfusate. A higher motor activity was also associated with a larger PD (more lumen negative). Both the absorptive and the secretory fluxes were thus enhanced by motility. The estimated absorptive flux was approximately twice as large as the secretory flux during periods of low motor activity, and four times as large during submaximal motor activity. We conclude that motor activity affects both absorptive and secretory mucosal function in a quantifiable manner. Information about the behaviour of the respective linkage functions may make it possible to model the intestinal absorption process in vivo.     

An objective method for determining the rate of primary healing in sutured wounds

Summary An objective method is presented for the purpose of evaluating the speed with which healing takes place in sutured wounds. The method of placing a wire loop and then removing it after 48 hours with the aid of a spring balance is explained. A short series of experiments was performed which attested to the general validity of the method.Presented by Active Member Acad, Med. Sci. USSR Prof. V. N. Chernigovsky     

Effects of motility on epithelial transport in the human descending duodenum.

The aim of the study was to determine how motility affects the balance between absorptive and secretory ion transport in the proximal human small intestine. Thirty-two healthy subjects and 16 patients (eight with villus atrophy, eight with normal duodenal biopsies) were studied. The absorptive sodium flux was estimated by measurement of bicarbonate absorption with a double-lumen perfusion technique. The secretory chloride flux was calculated from the ratio between the continuously recorded transmural potential difference (PD) and the epithelial parallel resistance, which was measured in forceps biopsies by square-wave current analysis. Graded variations in contraction frequency were obtained by recording during defined time periods before, during and after phase III of the migrating motor complex (MMC). Bicarbonate was absorbed by a process that led to CO2 formation, and both bicarbonate absorption and luminal PCO2 increased with contraction frequency. The motility-related PCO2 rise was reduced in patients with villus atrophy and by removal of bicarbonate from the perfusate. A higher motor activity was also associated with a larger PD (more lumen negative). Both the absorptive and the secretory fluxes were thus enhanced by motility. The estimated absorptive flux was approximately twice as large as the secretory flux during periods of low motor activity, and four times as large during submaximal motor activity. We conclude that motor activity affects both absorptive and secretory mucosal function in a quantifiable manner. Information about the behaviour of the respective linkage functions may make it possible to model the intestinal absorption process in vivo.     

An improved method for determining proteoglycans synthesized by chondrocytes in culture

An improved micro method for measuring sulfated glycosaminoglycans (S-GAG) in chondrocyte cultures using 1,9-Dimethylmethylene Blue (DMB) has been developed. By increasing the protein concentration in the DMB assay a soluble GAG-DMB complex is prolonged. Without bovine serum albumin (BSA) in the phosphate-buffered saline (PBS) medium, the half time for loss of absorbance was 18 min; with 1% BSA-PBS there was no loss of absorbance over this time period. The limit of detection in a 96 well microtiter plate assay was 2 micrograms/ml; for a cuvette assay it was 1 microgram/ml. Collagen, DNA and RNA did not interfere with this assay. Hyaluronate caused an increase in absorbance at 530 nm that was lost by preincubating with Streptomyces hyaluronidase. The increase in absorbance was due to a turbidity change because there was no color shift from 600 to 530 nm but rather a uniform increase in absorbance between 400 to 700 nm. To validate the assay, the S-GAG was measured in conditioned medium from primary bovine articular chondrocyte monolayer cultures. A protein synthesis inhibitor, cycloheximide, blocked proteoglycan synthesis by greater than 90%. A cytokine, Interleukin-1 alpha, caused a dose-dependent decrease in proteoglycan accumulation. Chondroitinase ABC digestion of the chondrocyte conditioned medium completely prevented reactivity with the DMB. By preincubating samples with specific enzymes, different types of S-GAG can be measured with this assay. This assay can be used to measure changes in proteoglycans synthesized by chondrocytes.     

An assessment of the Sensititre method for determining minimum inhibitory and bactericidal concentrations.

Minimum inhibitory and bactericidal concentrations of various antibiotics were determined for 90 strains of five organisms by Sensititre and compared with those obtained by conventional methods. Results by both methods corrleated well. The advantages and limitations of Sensititre are discussed.     

An experimental study on the effect of irradiation on motility of the small intestine]

In order to investigate the pathological condition of the intestinal tract after irradiation, experimental radiated intestinal tracts were prepared in adult rabbits, and motile functions of the terminal ileum of these rabbits were observed under electromyography. The results were also examined in relation to histological changes in corresponding region. The following results were obtained: 1. In the irradiation groups, findings different from the non-irradiation group were observed corresponding to the irradiation dose and time after the irradiation. 2. No correlation was observed between basic electric rhythm (BER) and irradiation dose. However, BER showed a slight decreasing tendency over time. 3. The active phase duration times in the irradiation groups were prolonged up to an irradiation dose of 80 Gy, then shortened in groups radiated with 120 Gy or more, as compared with the non-irradiation group. 4. The frequency of antiperistaltic propagation of electric stimuli showed an increasing tendency as the irradiation dose increased. 5. Dysrhythmia of electric discharge observed in the irradiation groups was enhanced by increase in irradiation doses and over time. 6. Motile function of the intestinal tract was enhanced in groups radiated up to 80 Gy and inhibited in groups radiated with 120 Gy or more. 7. In the 80 Gy irradiation group, motile function of the intestinal tract was enhanced at early phases after irradiation and inhibited at later phases. 8. Radiated intestinal tracts showed increasing tendencies in stimulation thresholds against agents such as Neostigmine and PGF2 alpha. 9. Histological changes in the intestinal wall were more marked in the mucous side. As the irradiation dose increased, the degrees of disorders were enhanced. At the early phases in the irradiation groups, inflammatory changes were the major histological changes seen. At later phases, chronic organic changes in the muscular layers, especially consisting of destruction of intermuscular plexus and degeneration decrease in ganglion cells, were marked. These irreversible changes were suggested to influence abnormalities in the motile function of the intestinal tract.     

An experimental study of the diurnal changes in colonic motility centering on defecation]

The following findings have been obtained as a result of making an assessment regarding the diurnal changes in colonic motility by means of continuous measurement of contractile waves by using strain gauge force transducers and roentgenographic observation in conscious dogs. 1. Before defecation, the contractile force of the wave was weak, frequency of its emergence was also small, and transfer of intestinal content was slow, showing decrease of colonic motility. 2. After defecation, the gradually increasing and decreasing contractile wave groups became clear, and the contractile force was intensified concurrently with increase of its emerging frequency. Transfer of intestinal content to the anal side was rapid, and recovery of colonic motility was observed. 3. The recovery of the colonic motility after defecation was observed regardless of digestive or interdigestive state. 4. By intake of food, increase of the colonic motility corresponding to gastrocolic response was observed, but it was due to the increase of emerging frequency of contractile wave, for which no change was observed in contractile force or duration in each individual waves. 5. It was suggested that the contractile motion which undergoes gradual increase and decrease is the basic pattern in the colonic motility and that the colonic motility changes by the differences of amount, shape and hardness of intestinal content, and decreases gradually along with increase of intestinal content, but the basic pattern of contractile motion is restored by inflow of intestinal content into the colon which became empty after defecation. From the above it was considered to be inadequate to use the pattern classification of digestive and interdigestive state for the analysis of colonic motility and that assessments should be made centering on defecation.