Effect of peripheral nerve stimulation on the dorsal horn cell activity in cats with cutaneous inflammation

There are some reports showing that an experience of long-enduring pain causes a change in the pain transmission system, suggesting a plastic nature of the nociceptive system. However, most of the studies concerning the analgesic effect of peripheral nerve stimulation dealt with normal animal or human subjects. So, the present study was undertaken to investigate the effect of peripheral nerve stimulation on the dorsal horn cell activity using a tonic pain model, which was made by producing a cutaneous inflammation. The main results are summarized as follows. 1) The evoked activity by electrical or natural stimulation as well as spontaneous activity was enhanced, and the receptive field size was also expanded by the inflammation. 2) Peripheral nerve conditioning stimulation reduced the C-response of the dorsal horn cell in the normal and inflamed group, and the degree of inhibition between the two groups showed no significant difference. 3) Inhibition of the C-response of the dorsal horn cells by peripheral conditioning stimulation was completely reversed by naloxone in the inflamed group whereas there was a partial block in the normal group.

Modulation of acute morphine tolerance by corticotropin- releasing factor and dynorphin a in the mouse spinal cord

Previously, we have demonstrated that intrathecally (i.t.) administered corticotropin-releasing factor (CRF) in mice produces stimulus-specific antinociception and modulation of morphine-induced antinociception by mechanisms involving spinal kappa opioid receptors. Recently, we also have found that CRF releases immunoreactive dynorphin A, a putative endogenous kappa opioid receptor agonist, from superfused mice spinal cords in vitro. Dynorphin A administered intracerebroventricularlly (i.c.v.) to mice has been shown to modulate the expression of morphine tolerance. In the present study, the possible modulatory effects of i.t. administered CRF as well as dynorphin A on morphine tolerance were studied in an acute tolerance model. Subcutaneous administration of 100 mg/kg of morphine sulfate (MS) to mice caused an acute tolerance to morphine-induced antinociception. The antinociceptive ED50 of MS was increased from 4.4 mg/kg (naive mice) to 17.9 mg/kg (4 hours after the injection of 100 mg/kg MS). To study the modulatory effects of spinally administered CRF and dynorphin A on the expression of morphine tolerance, CRF and dynorphin A were injected i.t. at 15 min and 5 min, respectively, before testing the tolerant mice by the tail-flick assay. The antinociceptive ED50 of MS in tolerant mice was decreased to 8.8 mg/kg and 7.1 mg/kg, respectively, after i.t. administration of CRF (0.1 nmol) and dynorphin A (0.2 nmol). In contrast, 0.5 nmol of alpha-helical CRF (9-41), a CRF antagonist and 0.4 nmol of norbinaltorphimine, a highly selective kappa opioid receptor antagonist, when administered i.t. at 15 min before the tail-flick test in tolerant mice, increased the antinociceptive ED50 of MS to 56.6 mg/kg and 88.8 mg/kg, respectively. These data confirmed the modulatory effect of dynorphin A on morphine tolerance and suggested that CRF, which releases dynorphin A in several central nervous system regions, also plays a modulatory role in the expression of morphine tolerance.

Use of a persistent photoconductive array in the learning of an optoelectronic neural processor

Persistent photoconductors of npnp doping-modulated amorphous silicon multilayers are investigated for the implementation of variable analog and nonvolatile synaptic weights of an optoelectronic neural processor. The time dependence of the persistent photoconductance of the amorphous silicon multilayers is characterized in experiments. The learning performance of an optical pattern classifier with the persistent photoconductive array is analyzed by computer simulations.

Internal intensity standards for heme protein UV resonance Raman studies: excitation profiles of cacodylic acid and sodium selenate

We examine the utility of SO4(2-), ClO4-, cacodylic acid, and SeO4(2-) as internal intensity standards for Raman spectral measurements of protein structure. We find that 0.1 M SO4(2-) and ClO4- perturb the protein tertiary structure of aquomethemoglobin (met-Hb) and its fluoride (met-HbF) and azide (met-HbN3) complexes. Changes occur for the tryptophan near-UV absorption bands, the iron spin state is altered, and the fluoride ligand affinity decreases. Concentrations of ClO4- and SO4(2-) as low as 0.1 M suppress the met-HbF quaternary R----T transition induced by the allosteric effector inositol hexaphosphate (IHP). In contrast, similar concentrations of cacodylic acid and SeO4(2-) show little effect on the hemoglobin tertiary or quaternary protein structures or upon the R----T transition induced by IHP. We measure the Raman cross sections of cacodylic acid and SeO4(2-) between 218 and 514.5 nm and find that for UV excitation they are ca. 5-fold larger than ClO4- or SO4(2-). Thus, cacodylic acid and selenate can be used at lower concentrations. Cacodylic acid and SeO4(2-) are superior Raman internal intensity standards for protein structural studies.

Optical implementation of a quadratic associative memory by using the polarization-encoding process

As a higher-order associative memory of a neural network, the quadratic associative memory is implemented holographically by using the polarization-encoding process. The use of polarization encoding to represent sign in the quadratic associative memory tensor is made by twisted nematic liquid-crystal light modulators. Experimental results of retrieving the stored objects from an incomplete input are presented.

Heterogeneous electron transfer of cytochrome c facilitated by polypyrrole and methylene blue polypyrrole film modified electrodes

Polypyrrole and methylene blue incorporated polypyrrole thin-film modified electrodes were prepared by the electrochemical polymerization method. These modified electrodes may facilitate heterogeneous electron transfer of cytochrome c with high electrocatalytic activity and good stability. Optical thin-layer spectroelectrochemical techniques were used to determine the characteristics of these electrochemical processes such as formal redox potential (E0), electron transfer number (n), and the apparent rate constant (ks.h0).

A comparison of the size of fenestrations in the internal elastic lamina of young and old porcine aortas as seen with the scanning electron microscope

The size of the fenestrations (windows) in the internal elastic lamina (IEL) of arteries may be important in the functioning of the blood vessel wall. The fenestrations are filled with collagen, muscle, and (or) ground substance, which must be removed to make the fenestration visible with the scanning electron microscope. All of the nonelastic components are removed with a hot alkali solution. Our experiments were designed to compare the fenestration size in the IEL of the thoracic aorta of young (6-8 weeks) and old (6-9 months) pigs. A protocol for digestion of young pig tissue was developed and showed that fresh young aortas should be digested in 0.1 M NaOH at 75 degrees C for 2 h and fixed tissue should be digested for 5 h. The average area of the fenestrations for young pig thoracic aortas digested for 2 h was 1.8 +/- 0.29 (SE) microns 2 and for the old pig aortas digested for 2 h was 1.7 +/- 0.11 (SE) microns 2. These values were not significantly different (p greater than 0.05), but the IEL from young pigs appeared rougher than the previously reported smooth IEL of the adult pigs.

Percutaneous transcatheteral biliary biopsy (PTBB)--a report of two cases

In two patients with obstructive jaundice, percutaneous transhepatic cholangiography (PTC) and percutaneous transhepatic biliary drainage (PTBD) were performed. During PTBD, the percutaneous transcatheteral biliary biopsy (PTBB) with the biopsy forceps of the gastrofiberscope was performed through the biliary stent catheter. Biopsy specimens were successfully obtained and histopathologic findings were satisfactory in both cases.

Properties of holographic associative memory prepared by the polarization encoding process

A new holographic associative memory (HAM) using optical polarization is proposed. Picture elements (pixels) of binary objects are encoded with two mutually perpendicular states of linear polarization, and they are stored in the HAM using a lensless diffuser system. Experimental results of recognizing various inputs are presented. Analytical expressions about the present HAM are derived, and results of computer simulation are also presented.

Arterial elastin as seen with scanning electron microscopy: a review

All large arteries contain elastin, collagen, and muscle which can be seen with light microscopy and transmission electron microscopy. Elastin forms an internal elastic lamina (IEL) in all arteries, but also forms multiple fenestrated sheets in the media of the aorta and other large arteries. The fenestrations in the media are larger than those in the IEL. The adventitial elastin is more fibrous and often contains tubular elastin surrounding vasa vasorum when prepared by removing all non-elastin by placing the aorta in 0.1 N NaOH at 70-75 degrees C for five hours. The fenestrations are larger near branches and in an experimentally created poststenotic dilatation. Atherosclerosis appears associated with both new elastin formation in early atherosclerosis and elastolysis in late disease.

Brain iron in patients with Parkinson disease: MR visualization using gradient modification

In patients with Parkinson disease, improved visualization of brain iron on a mid-field-strength magnet can be obtained with T2-weighted images and elimination of phase-encoding artifacts. A long echo delay time accentuates the loss of signal from brain iron. However, the long pulse sequence creates phase-encoding artifacts from CSF pulsations at the level of the basal ganglia. These artifacts are eliminated and resolving power increased with additional pulsing in the slice-selective and read gradients. Elimination of motion artifacts enhances visualization of brain iron in three ways: (1) extrapyramidal nuclei containing iron have better definition, (2) abnormalities are better identified, and (3) pseudolesions disappear. Our findings suggest there is significant improvement in the resolving power of brain iron on MR scans made with a mid-field-strength scanner when gradient modification is used.

Trial of specific antigen-mediated leukocyte adherence inhibition test in patients with chronic active hepatitis and hepatitis B carrier

In the pathogenesis of chronic active hepatitis, the importance of cell mediated immunity (CMI) has been emphasized. Leukocyte adherence inhibition (LAI) assay, which is one of the methods for analysis of the reaction of CMI, has been used to analysie the CMI of cancer patients.

The authors tried the specific antigen-mediated LAI assay in 40 patients with chronic active hepatitis, 19 patients carriers of hepatitis B virus, and in the 5 persons who have no anti-HBs in spite of receiving vaccination against HBV, and these were compared with 7 normal control subjects who had been exposed to hepatitis B virus previously.

The results were as follows: The NAI was 52.4±14 (mean ± standard deviation) in 7 normal control subjects who had been exposed to hepatitis B virus previously. The NAI was 20.6 ± 11 (mean ± standard deviation) in 40 patients with chronic active hepatitis. The value was significantly lower than that of the normal control group (P<0.001). The NAI was 49.7±17.8 (mean ± standard deviation) in 19 patients carriers of hepatitis B virus. The value was not significantly different from that of the normal control group (P>0.05). The NAI was 25.1±11 (mean ± standard deviation) in 5 persons who have no anti-HBs in spite of receiving vaccination against HBV. The value was significantly lower than that of the normal control group (P<0.05). In patients with chronic active hepatitis and hepatitis B virus carriers, we checked the LAI assay serially. The value of NAI was increased according to the improvement of clinical symptoms and normalization of transaminase, but the value of NAI was decreased according to the worsening of clinical symptoms and elevation of transaminase.

Scanning electron microscopic studies of the vasa vasorum of thoracic aortas

Using hot alkaline solution, the elastic laminae were extracted from aortas and observed with scanning electron microscopy. Vascular structures were found in the elastin layers of the tunica media in descending thoracic aortas of sheep, dogs, and pigs, and these tube-like structures were filled with elastomer which was injected through the heart of the animal in vivo. Sub-intimal microvessels were also found to be filled with the elastomer and it is concluded that vasa vasorum can exist close to the internal elastic lamina in these animals.

A morphological comparison of aortic elastin from five species as seen with the scanning electron microscope

The elastic laminae were extracted from thoracic aortas of adult animals including sheep, dogs, rabbits, cats and rats by treating them in hot alkaline solution (0.1 N NaOH at 75 degrees C) and observed with a scanning electron microscope. The elastic laminae are comprised of sheet-like internal elastic lamina, fibrous and membraneous elastin in tunica media, interlamellar fibers and hollow spaces which we presume were formerly filled with smooth muscle cells in the tunica media. These structures are the same in all five species except that the number of layers and the total thickness of the wall differs.

Mechanical anisotropy of purified elastin from the thoracic aorta of dog and sheep

Mechanical anisotropy was found in elastin from the wall of the thoracic aorta by testing digested vessels from seven mature dogs and five pregnant ewes. The elastin was purified by removing the muscle and collagen with 0.1 N NaOH at 75 degrees C for 5 h. Strips oriented circumferentially and longitudinally with respect to the vessel axis were cycled at increasing loads until failure. Combining the results for four dogs and three sheep the ultimate tensile strength was 405 X 10(3) +/- 155 X 10(3) SD N/m2 circumferentially and 189 X 10(3) +/- 85 X 10(3) SD N/m2 longitudinally. The difference is significant at p less than 0.01. The ultimate strain was not significantly different, 1.19 +/- 0.29 SD circumferentially and 1.01 +/- 0.26 SD longitudinally. At 0.4 strain, the Young's modulus for four samples from four dogs was 404 X 10(3) +/- 64 X 10(3) SD N/m2 circumferentially; the modulus for five samples from five dogs was 245 X 10(3) +/- 60 X 10(3) SD N/m2 longitudinally. The difference is significant at p less than 0.05. At 0.7 strain, the Young's modulus for four dogs was 486 X 10(3) +/- 82 X 10(3) SD N/m2 circumferentially and 343 X 10(3) +/- 62 X 10(3) SD N/m2 longitudinally. The difference is significant at p less than 0.05. The reasons for the anisotropy in terms of the structure are not obvious from preliminary studies using the scanning electron microscope with stretched samples.

Quantitative changes in the size of fenestrations of the elastic laminae of sheep thoracic aorta studied with SEM1

The elastic laminae were extracted from thoracic aortas of 6 adult sheep by treating them in 0.1 N NaOH at 75 degrees C, and the surface of internal elastic lamina (IEL) was observed for windows by scanning electron microscopy. The fenestration analysis on IEL showed that mean diameters of the holes ranged from 0.46 microns (+/- 0.013 SEM) to 1.35 microns (+/- 1.019 SEM), which is smaller than those of human cerebral arteries (7.0 +/- 0.34 at the apex of the bifurcation and 2.1 +/- 0.13 SEM microns in the straight sections; [3]), and mean densities ranged from 6,513 to 31,544/mm2. Both size and density of windows are found to increase when the digestion time in the hot alkaline solution is increased form 1 to 3 h. It is concluded that the IEL of the sheep thoracic aorta has smaller windows than human cerebral arteries and because of the wall thickness the thoracic aorta requires longer digestion times than human cerebral arteries.

Pancreatic pseudocyst simulating dilated biliary duct system on computed tomography

A case of pseudocyst simulating the biliary ductal system is reported. Several CT findings indicate that the biliary system was not involved: (a) no dilatation of the more proximal intrahepatic biliary radicles; (b) the gallbladder was not distended; (c) lucency extending to the left at the level of the pancreas; (d) a position more medial and anterior than anatomic for the distal common bile duct.

Is inert gas washout from the tissues limited by diffusion?

To determine the extent to which diffusion may limit the exchange of gases stored in the tissues, nine dogs were allowed to breathe an O2-N2-Ar mixture until saturation was achieved; the inspired gas was then changed to one containing neither N2 nor Ar, and the level of these two species in the arterial and in the mixed venous blood was monitored during the washout. A theoretical analysis shows that in a situation where peripheral gas transport is limited entirely by perfusion, the washout curves should be identical, provided concentrations are expressed as a fraction of the initial value. When the process is restricted by diffusion through the tissues, Ar is expected to lag because of its higher molecular weight. In all animals, the rate of elimination of the two tracers was the same, indicating that the time course of storage or release of inert gas from body stores is governed (mainly or entirely) by perfusion.

Studies on splenic megakaryocytes. I. Recovery of megakaryocytes from the splenic venous outflow

Spleens from 14 healthy adult cats were isolated and perfused with cell-free Ringer's solution. Histological studies on the splenic megakaryocytes, as well as a search for splenic megakaryocytes in samples of the splenic venous outflow, were performed. The samples of the splenic venous outflow contained a lower cellular concentration when perfusion was prolonged, but the number of megakaryocytes appearing in the venous samples increased. At least five different forms of megakaryocytes were observed from smears of the venous outflow: (i) unipolar, (ii) multipolar, (iii) foamy, (iv) mobile and (v) nuclear types. These types were also found in splenic venous outflow of dogs, kittens and bled cats. It is suggested that not only platelets but also the larger megakaryocytes can pass out of the splenic circulation. This may imply that megakaryocytes can be culled, matured in the splenic red pulp, and ultimately released into peripheral blood.

Endocardial surface structures of the feline heart observed with a scanning electron microscope

Internal surface structures of the auricular and ventricular chambers were studied with scanning electron microscopy. We observed vascular connections between the ventricular chamber and the coronary vessels, including cords and papillary muscles covering the lining of the endocardium. The endothelial cells covering the inner surface of the endocardium appeared to be functionally active with many microvilli similar to pinocytic microprojections of other endothelial cells. The pinocytic microprojections ranged between approximately 100 and 300 A in diameter. The epicardium contained mainly bundles of collagenous fibers.

Release of red cells from the slowly-exchanging splenic pool after noradrenaline administration

Isolated, denervated, cat spleens were perfused at constant flow with modified Ringer solution. Perfusion, pressure, outflow rate, and outflow red cell concentration were measured against time. After splenic perfusion by 500 ml solution the cell washout curve became a single exponential function, indicating that only cells from the most slowly exchanging red cell compartment remained (these are immature and abnormal cells which adhere to the fine structures of the red pulp). Splenic contraction was induced by injection of 5 mug noradrenaline into the inflow after perfusion by 600 and 1000 ml of fluid, respectively; outflow cell concentration rose 17-fold before returning to baseline value and 32% of red cells in the spleen were expelled. The time course of changes in cell concentration was similar in shape but delayed with respect to that of outflow rate. The transit time of the cells from the site of release to the splenic vein must have exceeded 40 s, which is consistent only with release from the red pulp. Furthermore, at the peak of the cell concentration curve the mean reticulocyte count was 37.8%. Thus immature and abnormal red cells, which comprise the slowly-exchanging compartment, are indeed released from the spleen during contraction.

Effects of acetate on myocardial contractility and epicardial ECG of isolated and perfused feline hearts

In isolated, perfused hearts, the effects of acetate on epicardial ECG and ventricular pressure were observed during various times of perfusion. Anions-Cl-and acetate-caused changes of ECG configuration, especially in the ST segments. These were different in Phase I (fast compartment) and Phase II (slow compartment).

Kinetics of the red cell washout from coronary vessels of isolated feline hearts

Twenty seven isolated feline hearts were perfused with cell-free oxygenated Ringer-Locke solutions. The concentration of red blood cells in samples of venous outflow collected from the coronary sinuses was determined by means of a Celloscope counter. Cellular concentrations decreased gradually as the perfusion time increased, and from 10(9) to 10(5) cells per millilitre after 300 ml perfusion. When the ventricular lumens were filled with residual blood (group I, 15 cats), several red cell peaks were superimposed on the smooth exponential decay curve of red cell washout. It is suggested that the peaks were caused by ejection of red cells from the ventricular lumens into communicating branches between the ventricular lumens and coronary capillaries. In cases of blood-emptied hearts (group II, 12 cats) these peaks did not occur, and mathematical analysis showed that summing three exponential functions could approximate the whole washout curve of red cells. This suggests that the coronary circulation may be described by three red cell compartments. The functional implication of this analysis for the microcirculation in the coronary vessels was discussed.