[Acute gastric ulcerations in rats with obstructive jaundice--with special reference to gastric mucosal blood flow]

The mechanism of acute gastric ulcerations in rats with obstructive jaundice was investigated in terms of the changes in the gastric mucosal blood flow. Further, the effect of vagotomy with or without obstructive jaundice was examined. One hundred and eighty-eight Sprague-Dawley rats weighing about 250 g were prepared and divided into 4 groups as follows; sham operation (control group), ligation of the bile duct (jaundiced group), vagotomy with pyloroplasty (vagotomized group), ligation of the bile duct and vagotomy with pyloroplasty (jaundiced and vagotomized group). After two weeks, water immersion and restraint stress procedures were performed in these 4 groups. The gravity of the gastric ulcerations was calculated by ulcer index. The gastric mucosal blood flow was measured by hydrogen clearance technique. The following results were obtained. The control group showed increased ulcer index and decreased gastric mucosal blood flow after the stress procedures. The jaundiced group showed significantly higher ulcer index and early, significant decrease of gastric mucosal blood flow compared to the control group after the stress procedures. The vagotomized group showed significantly decreased ulcer index after stress procedures compared to the control group, however, the gastric mucosal blood flow were unchanged between both groups before and after the stress procedures. The jaundiced and vagotomized group showed significant decrease of ulcer index and improvement of decrease of gastric mucosal blood flow compared to the jaundiced group. These data suggested that the significant decrease of gastric mucosal blood flow during the stress procedures was one of exacerbating factors of the acute gastric ulcerations in rats with obstructive jaundice, and vagotomy might prevent them by maintaining the gastric mucosal blood flow in obstructive jaundice.

[Serodiagnosis of Mycoplasma pulmonis infection in mice and rats by an enzyme-linked immunosorbent assay]

Murine antibody against Mycoplasma pulmonis (Mp) was detected sensitively and specifically in experimentally and naturally infected animals by an enzyme-linked immunosorbent assay (ELISA), using urease conjugated antimurine immunoglobulin. More than 98% of the experimentally infected mice and rats exhibited positive reaction in the ELISA two or more weeks after infection, and the titer remained for a prolonged period (up to one year) after infection. However, we failed to detect antibody in the sera of one-week-postinfected animals. Mice and rats from breeding colonies were tested with the ELISA and compared with isolation of Mp from the respiratory organs. Positive reactions were shown in the ELISA using the sera from 91% of the mice and 98% of the rats from which the organisms were isolated. Conversely, 97% of the mice and 78% of the rats among Mp-free animals showed negative results in the ELISA. The sensitivity and specificity of the complement fixation test, which has been used widely for serodiagnosis of Mp-infection, were apparently lower compared to those of the ELISA. From these results, the ELISA was found to be available for the serodiagnosis of Mp-infection in mice and rats.

Hymenolepis nana: worm recovery from congenitally athymic nude and phenotypically normal rats and mice

When eggs or mouse-derived cysticercoids of Hymenolepis nana were inoculated into previously uninfected congenitally athymic nude (rnu/rnu) rats of an outbred Rowett strain, they failed to mature in the intestinal lumen. They also failed to mature in phenotypically normal (rnu/+) littermates, except when these hosts were treated with cortisone acetate from the beginning of the lumen phase. The Rowett rat, either thymus-deficient or not, was susceptible to tissue cysticercoids but resistant to luminal adults. It is therefore considered to be an unnatural host, at least for mouse-derived H. nana. There was little or no difference in susceptibility to initial tissue cysticercoids between these nude rats and phenotypically normal ones. The normal rats became completely resistant to reinfection with eggs and no secondary cysticercoids developed in their intestinal tissue, whereas the nude rats showed unaltered susceptibility to secondary tissue cysticercoids. Thus, acquired resistance to egg challenge, assessed by the failure of tissue cysticercoid recovery, was thymus-dependent. However, innate resistance to both a primary egg dose, assessed by the low recovery rates of tissue cysticercoids, and to a primary cysticercoid dose, assessed by the failure of luminal adult recovery, were thymus-independent. The effect of cortisone acetate to initiate maturation of H. nana appeared to be unrelated to thymus function. In contrast, all mice, either thymus-deficient or not, were highly susceptible to both phases. The number of worms recovered was more than 10 times greater than that of cysticercoids established in the rat's intestinal tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Toxoplasma-induced activities of peritoneal and spleen natural killer cells from beige mice against thymocytes and YAC-1 lymphoma targets

Homozygous (bg/bg) and heterozygous (bg/+) beige mice were infected with Toxoplasma gondii, and splenic and peritoneal natural killer (NK) cell activities were assayed against YAC-1 lymphoma (NK-YAC) and thymocyte (NK-THY) targets. Although uninfected bg/bg mice were devoid of NK-YAC activity when compared with bg/+ mice, NK-THY activity was at a completely normal level. Both effector cells showed NK-1.2+ Thy-1.2 +/- asialo GM1+ asialo GM2+ phenotype. T. gondii infection induced a marked augmentation in splenic NK-YAC activity of bg/+ mice, whereas a slight increase was shown in the bg/bg mouse spleen cells. On the other hand, the infection did not change the splenic NK-THY activity of either strain of mice. An increased expression of Thy-1.2 antigen was shown on both NK-THY and NK-YAC effector cells from the infected mouse spleen. The T. gondii-induced augmentation was dramatic in the peritoneal cavity of the both mice. The activated peritoneal NK cells were of the NK-1.2- Thy-1.2+ asialo GM1 +/- asialo GM2+ phenotype and were considered to be generated from functionally inactive peritoneal cells. Splenic effector cells obtained from the infected mice were selectively depleted with target cell monolayer, whereas peritoneal cells from the infected mice were strongly absorbed by the target monolayers without selectivity. A weak but significant interferon (IFN) titer was detected in the peritoneum, but not in the spleen, of the infected mice. Most of the IFN titer was acid labile. Treatment with anti-IFN-alpha/beta resulted in partial decline of both NK and IFN activities of bg/bg mice, but not bg/+ mice. Thus, involvement of both IFN-alpha/beta and IFN-gamma in the generation of peritoneal NK cells and IFN-independent augmentation of splenic NK cells in toxoplasmosis were suggested.

Species and strain differences in sensitivity to Toxoplasma infection among laboratory rodents

Different susceptibilities to Toxoplasma infection were shown among various inbred and outbred laboratory rodents. On the basis of several criteria, the animals can be divided into three groups: (i) highly sensitive (S) mice, Syrian hamsters and Chinese hamsters; (ii) moderately sensitive (M) Mongolian gerbils and mastomyses ; and (iii) resistant (R) rats and Korean striped field mice. S and M hosts supported intraperitoneal growth of the parasites and died of acute infection. M hosts showed prolonged time to death and low fatality as compared with S hosts. Some R hosts died only when they had received an extremely large size of inoculum, accompanying poor intraperitoneal proliferation of the parasite. WM/Ms and WKY rats markedly resisted the infection. These hosts were considered to be useful models for studying infection of and immunity to toxoplasmosis.

Effect of Toxoplasma infection on the sensitivity of mouse thymocytes to natural killer cells

Thymocytes from mice 2 weeks after infection with Toxoplasma gondii resisted natural killer (NK) cell-mediated cytolysis in contrast to the high sensitivity of normal mouse thymocytes. The infected mouse thymocytes also failed to form conjugates with effector cells and to compete for cytolysis of NK sensitive targets. These effects were mediated, at least in part, by interferon-gamma because normal thymocytes became NK insensitive after incubation in the infected mouse serum which contained significant amount of interferon-gamma, and pH 2 treatment of the serum abolished the effect. An alternate possibility for the reduced NK sensitivity of the infected mouse thymocytes was the elimination of NK-sensitive cells from the thymus, since histopathological studies showed marked atrophy and clearance of NK-sensitive thymocytes in the cortex of thymuses of infected mice. Although T. gondii induced augmentation followed by suppression of the host splenic NK activity, it seems unlikely that this altered NK activity was responsible for the lowered NK sensitivity of the thymocytes.

Natural killer cell activities of several inbred strains of the guinea pig and their susceptibilities to rabbit antiserum directed to guinea-pig brain tissue

Natural killer (NK) cell activities of spleen and peripheral blood leukocytes from several inbred guinea-pig strains, established in this Institute, were assessed in an 18-hr 51Cr-release assay. As target cells in the NK assay, a human myeloid cell line, K562, appeared to be the most suitable among several cultured cell lines tested. Intensities of cytolysis were different from strain to strain, but generally high in JY-2, JY-4 and JY-10 and low in JY-1. Treatment of the effector cells with rabbit anti-guinea-pig brain tissue serum plus complement reduced the NK activity, whereas treatment with rabbit anti-guinea-pig thymocyte serum, or rabbit anti-asialo GM1 serum, plus complement showed no significant effect on the NK activity.

Augmented followed by suppressed levels of natural cell-mediated cytotoxicity in mice infected with Toxoplasma gondii

The cytotoxic activity of effector cells from mice infected with Toxoplasma gondii was tested in a 4- to 5-hr (51)Cr release assay, using RL 0001000 0011100 0101010 0001000 0001000 0011100 0100010 1000001 1000001 1000001 0100010 0011100 1 and YAC-1 target cells. They showed enhanced cytotoxicity with a peak on the 3rd day postinfection followed by suppression with a peak on the 12th day. The cytotoxicity seemed to be exhibited by natural killer (NK) cells because: (i) pretreatment of the effector cells with antiasialo GM(1) or antiasialo GM(2) plus complement abolished the cytotoxic activity; (ii) the altered cytotoxicity levels were also induced in nude mice; and (iii) the activity was elicited by nonadherent-nonphagocytic cells. The alteration occurred simultaneously in various lymphoid organs with a similar profile. Neither spleen nor bone marrow cells of 12-day-postinfected mice inhibited NK activity of uninfected mice. Culture fluids of the infected mouse spleen and bone marrow cells did not affect the normal mouse NK activity. The proportion of effector cells capable of binding to target cells was constant during the infection. There was no positive correlation between NK activity and serum interferon level; i.e., interferon was detected in the serum of 12-day-postinfected mice but not in that of 3-day-postinfected or uninfected mice. Passively administered interferon or polyinosinic-polycytidylic acid could not restore the suppressed NK activity of 12-day-postinfected mice. Moreover, in vitro treatment of spleen cells from 12-day-postinfected mice with interferon failed to restore the suppressed NK activity. These results suggested that after toxoplasma infection, defective sensitivity to interferon was induced in NK precursor cells, and differentiation to functionally active NK cells might be blocked.

The molar combining ratio of anti-albumin Fab' fragments to homologous and heterologous serum albumins

The number of antibody combining sites on bovine (BSA), goat (GSA) and sheep (SSA) serum albumins was studied using rabbit and chicken antibodies. In homologous reactions, the profiles of quantitative precipitations with chicken antibody were similar to those with rabbit antibody reported previously (12), and the antigenic valence in the extreme antibody excess zone was found to be 6-7 for each albumin. The univalent Fab' fragments of rabbit and chicken antibodies were prepared. The stoichiometry of the soluble complex formed with the Fab' fragment and fluorescence labeled albumin was analyzed by gel filtration, and the number of Fab' fragment molecules capable of binding to an albumin molecule was estimated. In a homologous reaction with both rabbit and chicken Fab' fragments, the Fab' to albumin combining ratio revealed from the molecular weight of the soluble complex was 14:1. In the heterologous reactions, the combining ratio was 5:1 for rabbit Fab' fragments to BSA, and 9:1 for chicken Fab' fragment to BSA. From the heterologous reactions between GSA and SSA, it was demonstrated that the combining ratios were 10-11:1 with rabbit Fab' fragment and 11-13:1 with chicken Fab' fragment.

Tumor-specific skin-reactive antigen solubilized from a syngeneic guinea pig liposarcoma by 3M potassium chloride

Tumor-specific and skin-reactive antigen of a syngeneic liposarcoma (H-10) of Hartley/F guinea pig was solubilized with 3M potassium chloride and purified by precipitation with 2M ammonium sulfate, followed by Sephadex G-200 gel filtration. The antigenic activity of 7 fractions obtained was estimated by the delayed-type skin reaction elicited in syngeneic animals immunized with H-10 cells admixed with BCG. Accurate relative activity of the fractions comparable to the skin reaction elicited by living H-10 cells was calculated by the parallel line assay method in which the dose-response curves of the fractions are compared with that of living cells. About 30 approximately 50 microgram protein of the 3 fractions eluted slowly from the Sephadex column elicited the skin reaction equivalent to that elicited with 1 X 10(6) of living H-10 cells. Tumor-specific skin reactivity per microgram protein of these 3 fractions was roughly 20 approximately 40 times higher than that of lyophilized cells.

Differential responses of canine myosin ATPase activity and tissue gases in the pressure-overloaded ventricle dependent upon degree of obstruction: mild versus severe pulmonic and aortic stenosis

Mild pulmonic stenosis, induced in dogs by banding the pulmonary artery, elevated right ventricular peak systolic pressure to 60% above the control and elevated right ventricular K+- and Ca2+- activated myosin ATPase activities. In contrast, severe pulmonic stenosis, which elevated right ventricular peak systolic pressure to 300% above the control, did not produce an increase in myosin enzymatic ATPase Vmax values but caused a decrease in myosin activity. Mild aortic stenosis, induced by banding the ascending aorta, forcing a transaortic pressure gradient of 25 mm Hg, caused an elevation in left ventricular muosin ATPase, whereas severe aortic banding, brought about by creating a transaortic pressure gradient of 55 mm Hg, never caused an elevation in left ventricular myosin enzymatic Vmax values, but, like severe pulmonic banding, caused a decrease in K+- and Ca2+- activated myosin activities. Normal left ventricular myosin Vmax values in mumol of PO4/mg-min at 37 degrees C were: K+ = 2.84 +/- 0.22, and Ca2+ = 0.97 +/- 0.14. For right ventricular myosin they were: K+ = 2.15 +/- 0.16, and Ca2+ =0.74 +/- 0.10. Analyses of tissue gases, based on mass spectrometry data, showed that the hypertrophied ventricles had an elevated tissue pCO2 and an elevation in the cGMP/cAMP ratio.