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Cells involved in the immune response. XII. The differing responses of normal rabbit lymphoid cells to phytohemagglutinin, goat anti-rabbit immunoglobulin antiserum and allogeneic and xenogeneic lymphocytes.

Cells of the different lymphoid organs in the normal adult rabbit were investigated for their capacity to respond in vitro to a number of stimuli, such as phytohemagglutinin (PHA), anti-rabbit immunoglobulin antiserum (GARIG) and allogeneic and xenogeneic lymphoid cells, and for their capacity to adsorb radioactively-labeled anti-immunoglobulin antiserum. The bone marrow cells responded minimally to PHA, GARIG, and the allogeneic and xenogeneic stimuli. The thymus cells were unable to respond to stimulation with GARIG although they responded to the other stimuli. The cells of the other lymphoid organs tested responded to all the mitogenic agents, to varying degrees. On the basis of the results presented and the findings of other investigators, it is concluded that: 1. The response of the cells to GARIG indicates a potential capacity to mediate humoral immunity and requires the presence of immunoglobulin or immunoglobulin-like recognition sites on the cell surface. 2. The response of the cells to PHA and allogeneic and xenogeneic cells indicates a potential capacity to mediate cellular immunity and does not necessitate the presence of immunoglobulin-recognition sites on the cell surface. 3. The thymus in the normal adult rabbit consists of cells capable of mediating cellular immunity only. 4. The other lymphoid organs appear to possess cells capable of mediating humoral and cellular immunity.

Animals↗

Induction of lymphoid cell chimerism in noninbred, histocompatible rabbits. A new model for studying allotype suppression in the rabbit.

Noninbred rabbits, matched with regard to the major histocompatibility complex (RLA-A and RLA-D loci) but mismatched for Ig allotypes, served as donors (adult) and recipients (newborn) of lymphoid cells. Lasting chimerism regularly followed the transfer of 1 x 10(8)-3 x 10(8) spleen, lymph node, or bone marrow cells, as indicated by the continued production of Ig with allotypic determinants of both donor and recipient. Typically, Ig of donor allotype accounted for 25-50% of total allotypic Ig at 4 wk of age and the amount of donor Ig produced remained stable for up to 20 mo. Total allotypic Ig levels remained normal in the chimeric rabbits. "Chimeric drift" or a gradual diminution of donor products over a period of several months, occurred in some individuals. Transfer of lymphoid cells from allotype-suppressed adult donors to newborns of appropriate allotypes did not result in specific suppression of the target allotype in the recipients. Other experiments showed that lymphoid cells from suppressed donors adoptively transferred to histocompatible recipients continued to synthesize Ig of the nonsuppressed type only. The suitability of using an outbred population of histocompatible but allotype-mismatched rabbits for analyzing allotype suppression and other immunoregulatory phenomena is demonstrated by the results presented here.

Animals↗

Digestibility of native and modified starches: in vitro studies with human and rabbit pancreatic amylases and in vivo studies in rabbits.

The effects of cooking and chemical modification of purified starches on the relative rates and extent of their hydrolysis were studied in vitro by using purified human and rabbit pancreatic amylases. Comparison was made with an in vivo study of postprandial glucose and insulin response in adult rabbits. Uncooked starches showed negligible hydrolysis in vitro, whereas cooking (10 min, 100 degrees C) increased both the rate and extent of hydrolysis of all starches. Soluble potato starch was the most and potato amylose the least hydrolyzed. Unmodified tapioca and waxy corn starch were hydrolyzed at the same rate and to the same extent as soluble potato starches. In most cases chemical modification did not change the rate and extent of hydrolysis of the starches. Minor differences between human and rabbit pancreatic amylase exist, but there is a general resemblance between the two amylases in their starch-hydrolyzing properties (correlation coefficient = 0.90; P less than 0.001). The in vivo study showed that uncooked starches elicited no detectable glucose and insulin responses, whereas all the cooked starches except amylose caused glucose and insulin responses comparable to the response seen when feeding glucose. Chemically modified starches (especially waxy corn acetylated distarch adipate) seemed to promote a faster rate of absorption, but the total glucose response (i.e., for the entire 180-min duration) was similar for modified starches and their unmodified counter-parts. The in vivo results showed an overall qualitative similarity to the in vitro results but presented a quantitative difference in the magnitude of the responses for various starch preparations. A good correlation exists between the in vitro and in vivo results (correlation coefficient = 0.84; P less than 0.01). This indicates that the action of pancreatic amylases is an important determinant in the digestion and absorption of these carbohydrates.

Amylases↗

Purification of a low-molecular-weight phospholipase A(2) associated with soluble high-molecular-weight acidic proteins from rabbit nucleus pulposus and its comparison with a rabbit splenic group IIa phospholipase A(2).

An intervertebral disc is a large peice of avascular cartilage rich in proteoglycans and water consisting of gelatinous nucleus pulposus and fibrous annulus fibrosus. The soluble fraction of rabbit nucleus pulposus exhibited unusually high Ca(2+)-dependent phospholipase A(2) (PLA(2)) activity (about 70% of the total PLA(2) activity). The soluble PLA(2) activity was 6-7-fold higher than those of rabbit annulus fibrosus and spleen. The PLA(2) was bound to an anion-exchange column at pH 7.4, and eluted near the void volume as a broad peak on gel-filtration on a TSKgel SuperSW3000 column developed with a buffer containing 0.1-0.2 M salt. When the gel-filtration column was developed in the presence of 1 M salt, almost all the PLA(2) activity was eluted near the total available volume. The soluble PLA(2) was purified to near homogeneity. A Ca(2+)-dependent PLA(2) was also purified from the fractions extracted with 1 M KBr from nucleus pulposus. For comparison, we purified a Ca(2+)-dependent PLA(2) from the KBr fraction of spleen. The splenic PLA(2) was identical to a group IIa PLA(2), as judged from its N-terminal amino acid sequences and mass spectra. On SDS-polyacrylamide gel electrophoresis the enzymes purified from the soluble and KBr fractions of nucleus pulposus both gave a major 15. 7-kDa band at the same position as splenic group IIa PLA(2). These results suggest that group IIa PLA(2) is associated with soluble high-molecular-weight proteins, most likely proteoglycans, in the extracellular matrix of rabbit nucleus pulposus.

Amino Acid Sequence↗

In vitro development of rabbit pronuclear embryos in rabbit peritoneal fluid.

The use of rabbit peritoneal fluid (PF) for the culture of rabbit embryos in vitro was evaluated. Development of zygotes cultured in PF and Earle's balanced salts solution (EBSS) + 10% fetal calf serum (EBSS/FCS) was compared. The effects of increasing the concentration of PF in EBSS and of culturing embryos in fractionated PF were also investigated. In addition, embryonic development in PF was compared to that in vivo. Development to hatching blastocysts was enhanced with PF (73%) compared to EBSS/FCS (3%, p less than 0.001). PF manifested greater mitogenic activity than EBSS/FCS, as indicated by higher cell number in embryos at 48, 72, and 96 h post-mating/hCG (p less than 0.001). PF also promoted blastocyst cell proliferation in a dose-dependent manner (r = 0.98, p less than 0.01); however, embryo growth remained slower than in vivo. Culture in the high (greater than 30,000 Da) molecular mass fraction of PF reduced incidence of hatching (56% vs. 92%, p less than 0.001) and mean cell number in Day 4 blastocysts (151 +/- 4 vs. 243 +/- 5, p less than 0.001). Rates of blastocyst hatching (10%) and cell number (110 +/- 3) were further reduced in the low (less than 30,000 Da) molecular mass fraction. When the high molecular mass fraction was dialyzed, embryos did not develop beyond the early morula stage. This suggests that the interaction or the synergy of high and low molecular mass components of PF is necessary for optimum development of rabbit embryos.

Animals↗

Herpes simplex virus type 1 ICP0 localizes in the stromal layer of infected rabbit corneas and resides predominantly in the cytoplasm and/or perinuclear region of rabbit keratocytes.

Herpes stromal keratitis (HSK) results from the reactivation of herpes simplex virus type-1 (HSV-1) in the cornea. The subsequent corneal inflammation and neovascularization may lead to scarring and visual loss. The cellular and molecular mechanisms underlying HSK remain unknown. The presence of stromal HSV-1 viral proteins or antigens in the HSK cornea remains a subject of debate. It was recently reported that HSV-1 ICP0 rapidly diffuses out of infected rabbit corneas. To investigate further the presence of HSV-1 ICP0 in the infected cornea, particularly in the corneal stroma, ex vivo confocal microscopy was used to scan rabbit corneas infected with the virus ICP0-EYFP, an HSV-1 derivative (strain 17+) that expresses ICP0 fused to the enhanced yellow fluorescent protein (EYFP). These results demonstrate that ICP0 is expressed in the corneal epithelium and stromal cells (keratocytes) of infected rabbit corneas throughout acute infection. Furthermore, expression of ICP0-EYFP appears localized to punctate, granular deposits within stromal keratocytes, showing both a cytoplasmic and perinuclear localization. These findings provide new data demonstrating that anterior corneal keratocytes become infected and express ICP0 during acute HSV-1 infection.

Animals↗

Sialidase in rabbit blood. Characterization of sialidase purified from rabbit erythrocyte membrane.

Sialidase activities of rabbit blood cells and serum were measured. The leucocyte particulate fraction showed the highest specific activity of sialidase towards mixed gangliosides and sialyllactose, and the cytosolic fraction showed for fetuin. Predominant sialidase activity in the blood was detected in erythrocyte particulate fraction when mixed gangliosides were used as substrate. The sialidase for ganglioside was solubilized from the erythrocyte ghosts by using Triton X-100. The solubilized sialidase was purified 1886-fold by sequential chromatographies on DEAE-cellulose, EAH-Sepharose 4B, Octyl-Sepharose CL-4B, Sephadex G-100, concanavalin-A--Sepharose, N-(p-aminophenyl)oxamic acid-agarose and Heparin-Sepharose CL-6B. The optimum pH of purified sialidase was 4.5 for ganglioside mixture, and this enzyme exhibited M(r) = 48,000 by gel filtration. When the purified sialidase was subjected to SDS/PAGE, a major sialidase-active protein band at M(r) = 54,000 and another fainter inactive protein band with M(r) = 115,000 were observed. The purified enzyme was active towards oligosaccharides, gangliosides, fetuin glycopeptide and 4-methylumbelliferyl alpha-D-N-acetylneuraminic acid except for glycoproteins tested. Fe2+, Fe3+ and dithiothreitol significantly inhibited the enzyme activity, while Triton X-100 activated the enzyme. Inside-out vesicles and unsealed ghosts of rabbit erythrocyte showed the sialidase activity for mixed gangliosides but not for resealed ghosts or intact erythrocytes. These results indicate that the active site of this sialidase is oriented mainly on the inside of the erythrocyte membrane and not on the outside. Treatment of rabbit erythrocyte unsealed ghosts with phosphatidylinositol-specific phospholipase C liberated no sialidase activity toward mixed gangliosides from the ghosts.

Animals↗

Effect of UK-84149 on voltage-activated calcium currents of single smooth muscle cells from guinea-pig and rabbit jejunum and rabbit coronary artery.

1. Smooth muscle cells of the longitudinal muscle of the guinea-pig and the rabbit jejunum and rabbit coronary artery were dispersed by enzyme treatment and recordings of membrane current were made in the standard whole cell voltage-clamp mode and by perforated patch technique. The effect of UK-84149 on the voltage-dependent calcium inward current of single isolated smooth muscle was studied at room temperature. 2. When inward and outward currents were evoked by stepping to 0 mV or + 10 mV from -80 mV every 20 s, UK-84149 reduced the voltage-dependent inward current in guinea-pig jejunum smooth muscle cells with a ID50 of 2.3 microM, and also reduced voltage-dependent outward current with a ID50 of 7.2 microM. The effect of UK-84149 was difficult to wash out. 3. The inactivation of the inward current was studied by holding at various potentials for 10 s before evoking inward current at a test potential of 0 mV. The voltage-inactivation curve was shifted to the left by 3 microM UK-84149. The voltage at which current was 50% available (Vh) was changed from -37 +/- 2 mV to -50 mV +/- 2.2 (n = 6, means +/- s.e. mean). 4. When inward current was evoked by stepping to 0 mV from -80 mV for 50 ms, every 20 s, nicardipine immediately, and verapamil and UK-84149 slowly, reduced the peak amplitude. Inhibition by the latter two drugs depended on the number of stimulations applied. So, like verapamil, UK-84149 had a use-dependent action. 5. The effect of UK-84149 on inward current from rabbit jejunum and coronary artery smooth muscle cells was compared with the effect of nicardipine and D600. When inward current was evoked by stepping to 0 mV from - 80 mV every 20 s, UK-84149 inhibited inward currents from both types of smooth cell with an ID50 of 1.7 microM for jejunum and an ID50 of 3.2 microM for coronary artery. ID50 values of D600 were 8.1 microM for jejunum and 3.9 microM for coronary artery. ID50 values of nicardipine were 24 nM for jejunum and 12 nM for coronary artery.6. The results of the present studies indicate that UK-84149 has a calcium-antagonist action that can explain its inhibitory action on bowel motility. Its bowel selectivity may arise due to its use-dependent,and persistent, action.

Animals↗

Fever induced in rabbits by intraventricular injection of rabbit and human serum albumin.

1. Intraventricular injection of rabbit and human serum albumin, and rabbit endogenous pyrogen produced dose-dependent fevers in rabbits. The pyrogenicity of albumin was less than one-twentieth of the pyrogenicity of endogenous pyrogen. 2. Fevers induced by ventricular albumin were significantly suppressed by intraventricular injection of indomethacin which is a cyclooxygenase inhibitor. In contrast, subcutaneous injection had no effect. 3. Ventricular endogenous pyrogen induced several of the acute phase responses, i.e. decreases in the plasma concentration of iron and zinc, and increases in both the plasma concentration of copper and the white blood cell count. Albumin induced none of these responses. 4. It is concluded that fever induced by ventricular albumin is processed by prostaglandins synthesized within the central nervous system. However, ventricular albumin does not activate the central mechanism to induce acute phase responses.

Animals↗

Autoimmune response in rabbits injected with rat and rabbit liver ribosomes.

Autoimmune hemolytic anemia and leukopenia, circulating autoantibodies for erythrocytes, leukocytes, and ribosomes; pathological changes in liver, spleen, heart, brain, and kidneys were produced in rabbits injected with rat or rabbit liver ribosomes. The hematologic and pathologic changes were reproduced by injection of anti-ribosomal serum into normal rabbits. The autoantibody specificity was related primarily to nucleotides and nucleosides.

Animals↗

Comparative penetration of azlocillin and mezlocillin into cerebrospinal fluid of normal rabbits and rabbits with experimentally induced Pseudomonas aeruginosa meningitis.

The impacts of meningeal infection with Pseudomonas aeruginosa and route of drug administration on the penetration of azlocillin and mezlocillin into the cerebrospinal fluid of rabbits were evaluated. The penetration of both agents was increased to a similar degree in rabbits with meningitis compared with normal rabbits. The increase in penetration was greater after intravenous administration than after intramuscular administration.

Animals↗

Production of immunoglobulin M (IgM) autoantibodies to IgG in rabbits inoculated with Mycoplasma salivarium cells grown in medium supplemented with rabbit serum.

Mycoplasma salivarium cells propagated in PPLO broth (Difco Laboratories, Detroit, Mich.) supplemented with rabbit serum (10% [vol/vol]) and harvested by centrifugation were shown to contain rabbit immunoglobulin G (IgG) (approximately 4 to 10% of total cell proteins) and to produce IgM autoantibodies to IgG when inoculated into rabbits.

Animals↗

Intra-articular yttrium 90 in rabbits. Comparison of behaviour of various radiocolloids in rabbits and in man.

Comparative studies of the retention of various yttrium 90 radiocolloids and of noncolloidal yttrium 90 chloride were performed in rabbits with arthritis induced in one knee. Two colloids, the citrate and resin forms, showed a statistically significant difference in retention between inflamed and normal knees, isotope being retained better in the normal knee. Marked differences were found in the handling of the various yttrium preparations in rabbits compared with previously reported results in man. These differences suggest that the rabbit with induced arthritis is not a suitable model in which to test retention of different radiocolloids before use in man.

Animals↗

Density and kinetics of I(Kr) and I(Ks) in guinea pig and rabbit ventricular myocytes explain different efficacy of I(Ks) blockade at high heart rate in guinea pig and rabbit: implications for arrhythmogenesis in humans.

BACKGROUND: Class III antiarrhythmic agents commonly exhibit reverse frequency-dependent prolongation of the action potential duration (APD). This is undesirable because of the danger of bradycardia-related arrhythmias and the limited protection against ventricular tachyarrhythmias. The effects of blockade of separate components of delayed rectifier K(+) current (I(K)) may help to develop agents effective at high heart rate. METHODS AND RESULTS: We assessed the density and kinetics of the 2 components of the delayed rectifier K(+) current, I(Kr) and I(Ks), in rabbit and guinea pig ventricular myocytes. The effects of their specific blockers (chromanol 293B for I(Ks) and E-4031 for I(Kr)) on the action potential was studied at different heart rates by use of whole-cell patch-clamp techniques. In guinea pig ventricular myocytes only, blockade of I(Ks) causes APD prolongation in a frequency-independent manner, whereas blockade of I(Ks) in rabbit ventricular myocytes shows reverse frequency dependence, as does blockade of I(Kr) in both species. This result can be explained primarily by the higher density of I(Ks) in guinea pig ventricle and by its slow deactivation kinetics, which allows I(Ks) to accumulate at high heart rate because little time is available for complete deactivation of it during diastole. CONCLUSIONS: Density and kinetics of components of I(K) explain why blockade of I(Ks) is more effective at high heart rate in the guinea pig ventricle than in the rabbit ventricle, without adverse effects at low heart rate.

Action Potentials↗

Angiotensin converting enzyme concentrations in the lung lavage of normal rabbits and rabbits treated with nitrogen mustard exposed to hyperoxia.

Increased concentrations of angiotensin converting enzyme (ACE) were found in lung lavages from rabbits exposed to hyperoxia for 72 h and the concentrations of ACE were correlated with ratios of extravascular lung water to body weight (r = 0.69, p less than 0.05) and albumin concentrations in lung lavages (r = 0.89, p less than 0.01). In parallel studies, rabbits treated with nitrogen mustard in which granulocytopenia was maintained throughout the 72-h hyperoxic exposure period had less evidence of edematous lung injury and lower concentrations of ACE in their lung lavages than similarly treated rabbits in which granulocytopenia was not maintained. The results suggested that granulocytes contribute to acute edematous lung injury from hyperoxia and that ACE concentrations in lung lavages reflect this process.

Agranulocytosis↗

The role and fate of rabbit and human transcobalamin II in the plasma transport of vitamin B12 in the rabbit.

Previous studies have shown that plasma transcobalamin II (TCII) facilitates the cellular uptake of [57Co] vitamin B12 (B12) by a variety of tissues, but the lack of an intrinsic label on the protein moiety of the TCII-B12 complex has made it impossible to determine the role and fate of TCII during this process. We have labeled homogensous rabbit and human TCII with 125I-labeled N-succinimidyl-3-(4-hydroxyphenyl) propionate and have performed in vivo experiments in rabbits. When 125I-labeled rabbit TCII-[57Co] B12 and 131I-labeled bovine albumin were simultaneously injected intravenously, we observed that 125Iand 57Co were cleared from plasma at a faster rate (t1/2 = 1 1/2 h) than 131I and that 125I and 57Co were present in excess of 131I in the kidney, liver, spleen, heart, lung, and small intestine 1/2 h after injection. Later, 57Co remained in excess of 131I, but the ratio of 125I to 131I decreased progressively in all of these plasma and were rapidly excreted in the urine. After 1 h following injection, 57Co was present in excess of 125I in the plasma...

Animals↗

Coronary artery aneurysms develop in weanling rabbits with serum sickness but not in mature rabbits. An experimental model for Kawasaki disease in humans.

The involvement of the cardiovascular system in rabbits with serum sickness is similar of that in Kawasaki disease, both with respect to the histologic changes of the myocardium, the valves, the coronary arteries, and the aorta and to the sequence with which they appear. Although coronary arteritis appears the same histologically, aneurysms did not occur in mature rabbits, even in case of necrosis of an arterial segment with deletion of muscle and elastic tissue. On the other hand, weanling rabbits with serum sickness had a tendency to develop aneurysms of coronary arteries, despite little cellular infiltration and reactive fibrocellular hyperplasia. The age factor thus appears to play an important role in the development of coronary aneurysms in Kawasaki disease, irrespective of the underlying mechanism, be it a markedly increased permeability to mediators through degenerated endothelial cells, or primary degenerated muscle cells with marked thinning of the media without much inflammatory cellular reaction. Furthermore, this study provides an insight into the long-term prognosis of transient dilatation of coronary arteries in the acute stage of Kawasaki disease.

Age Factors↗

Development of an ELISA for detection of myxoma virus-specific rabbit antibodies: test evaluation for diagnostic applications on vaccinated and wild rabbit sera.

An enzyme-linked immunosorbent assay (ELISA) was developed and compared with 2 reference diagnostic tests (indirect immunofluorescence [IF] and complement fixation) to detect myxoma virus-specific antibodies in sera from 50 rabbits experimentally vaccinated with an attenuated strain of myxoma virus or with a Shope fibroma virus. The ELISA was highly specific (100% specificity) and sensitive (100%, 21 days after homologous vaccination). In a comparison of the ELISA with the IF test in 128 wild rabbits from France, discrepant results were obtained in only 11 (8.6%) animals, which were positive with the ELISA and negative with the IF test. The higher sensitivity and the good specificity of the ELISA was confirmed in a serologic survey of 118 rabbits from 2 Kerguelen (Indian Ocean) islands, where the prevalence of myxomatosis varied considerably. The ELISA is an alternative serologic test for diagnosis, vaccine evaluation, and seroepidemiologic surveys of myxomatosis.

Animal Diseases↗