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PubMed1975

Transplantable immunoglobulin-secreting tumors in rats. VI. N-terminal sequence variability in LOU/C/Wsl rat monoclonal heavy chains.

Most of the spontaneous ileocecal immunocytomas of LOU/C/Wsl strain rats secrete large amounts of monoclonal immunoglobulins. Amino acid sequence studies were undertaken on the heavy chains of 13 of these proteins and on pooled heavy chains from LOU rats to define the structural variability in the amino terminal region of the rat heavy chain. Characteristic VHIII sequences were found in both the myeloma proteins and the heavy chains from the pool. The data confirm previous conclusions concerning the rat VHIII subgroup that had been derived from studies of pooled heavy chains from Sprague-Dawley rats. In particular phylogenetically associated residues, identical to those previously determined in the Sprague-Dawley pool, were found in the LOU/C/Wsl rat myeloma proteins. There were two unexpected findings: 1) hypervariability at position 16 of the rat VHIII myelomas as contrasted with more than 90% glycine in the pool, and 2) a striking homology of one rat myeloma heavy chain with the variable region of the MOPC 315 mouse alpha-chain. The findings show that the rat myeloma system provides useful proteins for sequence analysis but indicate that some sequence pattern differences can be detected between the myeloma proteins and pooled immunoglobulins from this species.

Amino Acid Sequence↗
PubMed1975

Antigens on mouse and rat lymphocytes recognized by rabbit antiserum against rat brain: the quantitative analysis of a xenogeneic antiserum.

Quantitative assays for measuring the binding of xenogeneic antiserum to dispersed cell suspensions are described. Cells were incubated with unlabeled xenogeneic antiserum and the antibody bound measured indirectly by a second binding step with 125I-labeled anti-immunoglobulin antibody. This indirect radioactive binding assay was calibrated by measuring, with a radioimmunoassay, the true amount of antibody bound in the first step. With these methods one can measure the strength of antisera, quantitate the number of antigenic sites, and partially differentiate determinants being recognized on cell surfaces. The binding of rabbit anti-rat brain antiserum to rat and mouse lymphocytes was analyzed in detail. After absorption of the antiserum with rat liver, the antibody remaining recognized lymphocyte antigens that were distributed among various rat and mouse tissues in quantities identical to Thy-1.1 antigen. Thus, at saturation, 670 000 Ig molecules from liver-absorbed rabbit antiserum were bound per rat thymocyte, and the antiserum bound to 90%, 21%, 4% and 2% of rat thymocytes, spleen, lymph node and thoracic duct lymphocytes, respectively. With mouse tissues, 90% 24% and 50% of thymocytes, spleen and lymph node cells, respectively, were labeled. In rat brain the concentration of xenoantigen increased with age, while in thymocytes the full adult amount was present at birth. Three antigenic determinants could be defined with the liver absorbed rabbit antiserum: the Thy-1.1 antigen, a rat specific antigen and an antigen cross-reacting between rat and mouse tissues. All 3 may be on the Thy-1 molecule. The anti-brain antiserum contained about 0.05 mg/ml of antibody specific to these xenoantigens.

Age Factors↗
PubMed1975

Subpopulations of multiparous rat lymph-node cells cytotoxic for rat tumour cells and capable of suppressing cytotoxicity in vitro.

Lymph-node cells (LNC) from multiparous pregnant rats were separated on columns prepared from nylon wool, and tested for cytotoxicity against target tumour cells. Reactivity of LNC towards hepatoma D23 and mammary carcinoma AAF57 was demonstrated in cell populations retained on the nylon wool, and not with cells eluted from the column. Although only 25% of the samples of unfractionated LNC were cytotoxic for tumour cells, retained cell fractions were cytotoxic in 11 out of 12 tests (p = less than 0.05). Similarly retained LNC were also cytotoxic for 15-day-old embryo cells but not for normal adult rat fibroblasts. Using multiparous rat serum it was shown that the reactivity of the retained LNC population could be abrogated in eight out of 11 tests (p = less than 0.05). The LNC population recovered from the nylon wool constituted 28 to 35% of the original LNC preparation, and consisted of 60-70% Ig-bearing cells together with a subpopulation of cells responding to soluble PHA. Separation of multiparous LNC on glass beads coated with rat Ig and then rabbit anti-rat Ig (in excess) also demonstrated the retained cell population to be cytotoxic against tumour cells. Approximately 17-20% of the original cell population was recovered from cells retained on the column, and consisted of an enriched Ig-bearing cell population (65-80% Ig-bearing cells) and LNC responsive to PHA. Carbonyl iron treatment of multiparous rat LNC was found to remove detectable cytotoxicity from multiparous rat LNC preparations. The cytotoxicity of multiparous rat LNC retained on nylon wool was also abolished following incubation with carbonyl iron. Definite conclusions as to the nature of the effector cell cannot be drawn from this test, since carbonyl iron treatment was found to remove not only phagocytic cells from LNC preparations but also a proportion of other cell populations including Ig-bearing lymphocytes... In addition to detecting a cytotoxic LNC population reactive towards tumour-associated embryonic antigens (retained fractions from nylon-wool column separation), a subpopulation of multiparous rat LNC was demonstrated in cell fractions eluted from the nylon wool which was shown to suppress the cytotoxicity of the retained multiparous LNC population. The exact nature of this subpopulation of LNC and the mechanism of action is at present not known.

Animals↗
PubMed1976

Rescue of a rat tropic rat hepatoma virus pseudotype Kirsten sarcoma virus by co-cultivation of hepatoma tissue culture cells with K-NRK cells.

A rat tropic rat hepatoma virus pseudotype Kirsten sarcoma virus has been rescued from a co-culture of rat hepatoma tissue culture cells, HTC-HI, with Kirsten murine sarcoma transformed non-producer rat kidney cells (K-NRK). The virus complex, RHHV-KiMSV, released from the co-culture exhibited cell transformation ability on normal rat kidney (NRK) cells and showed a restricted host range limited to rat embryo fibroblasts and other normal rat cell lines. Evidence derived from indirect immunofluorescence assays demonstrated the association of rat helper virus specific gs-I and gs-3 antigens with RHHV-KiMSV transformed cells. RHHVKiMSV is currently being cultured at a titre as high as 10(4) f.f.u./ml in tissue culture, and thus offering opportunity for biochemical studies of rat viruses.

Animals↗
PubMed1975

1. The effect of dietary fat on the host-parasite relations in cotton rat filariasis. 2. Host-parasite relations in the progeny of cotton rats fed protein deficient diets and infected with filariasis-a preliminary report. 3. Immunoglobulin levels in the early stages of infection with filariasis in cotton rats with and without dietary protein deficiency. 4. Action of aliphatic alcohols on aquatic stages of mosquitoes.

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Alcohols↗
PubMed1975

The effect of immunizing female rats with modified rat pituitary extract.

Immune reactions to a number of hormones have been induced, but information is lacking on the feasibility of inducing immune reactions to homologous gonadotropins. Female rats immunized with diazotized and tyrosylated rat pituitary extract containing gonadotropic activity and emulsified in complete Freund's adjuvant expressed various reproductive disturbances such as increased cycle length (7.0 days), increased number of sterile matings, reduced implantation in animals becoming pregnant, and reduced ability to carry fetuses to term. These effects were not exhibited by rats immunized similarly with diazotized or tyrosylated rat pituitary extract containing no detectable gonadotropic activity. Rats not becoming pregnant had a significantly higher antibody level to rat luteinizing hormone than did rats becoming pregnant. No significant elevation of rat follicle-stimulating hormone antibodies was noted. It is concluded that auto-immune reactions to gonadotropins can be induced and that very low levels of antibodies have a significant effect on reproduction.

Animals↗
PubMed1976

Characterizatiion of rat genetic sequences of Kirsten sarcoma virus: distinct class of endogenous rat type C viral sequences.

The nucleic acid sequences found in DNA and RNA from rat cells which are homologous to Kirsten sarcoma virus have been characterized. The homologous sequences are present in multiple copies per diploid rat cellular genome in a variety of different rat cellular dna's. In certain cells that constitutively express only low levels of sequences homologous to Kirsten sarcoma virus, bromodeoxyuridine treatment leads to the expression of high levels of these sequences in RNA. Supernatants from cell lines producing the sequences homologous to Kirsten sarcoma virus contain high levels of these sequences which are purified to the same degree as the previously known rat type C viral nucleic acid sequences by type C particles being released from such cells. The results indicate that the sequences in rat cells homologous to Kisten sarcoma virus have three characteristics of known mammalian type C viruses, and suggest that at least part of Kirsten sarcoma virus rat-derived sequences represent a distinct class of endogenous rat type C virus that has no detectable homology to the other known class of endogenous rat type C virus.

Animals↗
PubMed1977

Pulmonary insulin responsivitiy: in vivo effects of insulin on the diabetic rat lung and specific insulin binding to lung receptors in normal rats.

Adult rats were rendered diabetic by a single iv injection of streptozotocin (70 or 75 mg/kg). In these rats, serum insulin fell to minimal levels during the 48 h following drug treatment, and this was roughly paralleled by a progressive decrease in the ability of the lung to oxidize glucose. The addition of insulin to diabetic rat lung slices in vitro had no restorative effect on the depressed glucose oxidative rate during a 2 h incubation period; however, two daily treatments of the rats with 1 unit of protamine, zinc insulin completely restored lung glucose oxidation rate to normal, without significantly reducing the hyperglycemic state of the rats. An examination of the temporal changes in glucose utilization by the rat lung after acute insulin treatment revealed that the diabetic lung responded directly to serum levels of insulin, whereas the normal lung appeared to be unaffected by serum insulin levels as hihg as 87 ng/ml. The reduced rate of glucose oxidation in the diabetic lung was apparent after perfusion of the lung with glucose-free medium, and was characterized by a significant reduction in Vmax without an alteration in Km. This was attended by a depressed ability of the lung to incorporate [3H]leucine into protein and an increased ability to produce lactate, but hexose monophosphate shunt activity was normal. Specific receptors for insulin have been identified and partially characterized in crude membrane preparations of normal rat lung. The interaction of insulin with these receptors was rapid, reversible, saturable, and was dependent upon time and temperature. The binding of labeled insulin was inhibited by low concentrations of unlabeled insulin and by high concentrations of proinsulin, whereas it was unaffected by the presence of glucagon, gastrin, prolactin, ACTH, or growth hormone in microgram amounts. These observations suggest that insulin regulates the transport and utilization of glucose in the rat lung, and that this tissue contains specific receptors for insulin.

Animals↗
PubMed1977

Metabolic clearance of rat prolactin in the lactating and non-lactating rat.

The metabolic clearance of rat prolactin, assessed by the continuous infusion to equilibrium method, increased from 0-77 to 2-15 ml/min in lactating and from 0-65 to 1-75 ml/min in non-lactating rats as the infusion rate was increased from 100 to 472 ng/min. The clearance rate of rat prolactin did not increase when large doses of ovine prolactin were infused simultaneously with rat prolactin. The clearance rates computed from equilibrium levels of immunoreactive 131I-labelled rat prolactin in plasma were highly correlated with, but were considerably greater than, those computed from unlabelled rat prolactin which was infused simultaneously. In lactating and non-lactating rats, the clearance of each prolactin tested (RP-1, B-1, Nicoll's secreted and 131I-labelled) increased and had stabilized within the 30-35 min of infusion of each new higher dose of the hormone. The ability of the rat to clear quickly greater amounts of prolactin from the circulation as the infusion rate increases implies that plasma prolactin concentrations do not necessarily mirror the rate of prolactin secretion from the pituitary.

Animals↗
PubMedDate not supplied

[Somatotropin control of glucose transport and glycogen biosynthesis in the incubated diaphragm of hypophysectomized rats and rats with alloxan diabetes].

A study was made of the influence of somatotropic hormone of the hypophysis (STH) on the C14-glucose transport and on the C14-glucose incorporation into the glycogen of the incubated diaphragm of intact rats (group 1), hypophysectomized rats (group 2), rats with alloxan diabetes (group 3), and rats with combined exclusion of the hypophysis and the pancreas functions (group 4). The diaphragm of hypophysectomized rats had an increased capacity to the C14-glucose uptake from the medium and of incorporating it into glycogen, apparently on account of exclusion of the hormones group depending on the hypophysis, with the contrainsular action (STH, ACTH, TTH). On the contrary, the basal rate of the processes studied in the muscles of insulin-deficient rats (group 3) displayed a significant reduction. Alloxan exclusion of the B-cell function in the hypophysectomized rats (group 4) diminished the accelerated glucose transport and glycogen synthesis in the muscle. STH added to the incubation medium stimulated the glucose transport and the glycogen synthesis in the diaphragms of animals with altered endocrine homeostasis (groups 2, 3, 4). Muscles obtained from intact animals were refractory to the STH action. The most STH-sensitive were muscles of hypophysectomized animals (an increase of glucose absorption by 32%, and of C14-glucose incorporation--by 77%). Incubation of the muscles of rats suffering from alloxan diabetes with STH was also accompanied by increased rate of glucose transport and glycogen synthesis; this effect was less pronounced, however. The data obtained indicated that the regulation of carbohydrate metabolism in the muscle tissue with STH was individual, not mediated through any other hormone.

Alloxan↗
PubMed1976

Na-K-adenosine triphosphatase in the kidney of rats with renal hypertension and spontaneously hypertensive rats.

The rats with chronic renal hypertension caused by constricting one renal artery, exhibit a decrease in the activity of Na-K-ATPase in the outer medulla of the "untouched" kidney, as compared to this activity in the kidneys of intact normotensive rats and in the "untouched" kidney of the rats where renal artery constriction did not result in hypertension. There were no differences between the control normotensive Wistar rats and the spontaneously hypertensive rats (SHR) in the prehypertensive and early hypertensive stages (at the age of 6-8 weeks) as far as the activities of Na-K-ATPase and oxidoreductases (SDH and LDH) in the renal cortex, the outer and inner medulla are concerned. The spontaneously hypertensive rats with chronic hypertension had at the age of 16-20 and 27-29 weeks lower activity of Na-K-ATPase, SDH, and LDH in the outer renal medulla than the control normotensive Wistar rats. The experimental results indicate that in chronic arterial hypertension there is a decrease in the activity of Na-K-ATPase, in the outer renal medulla, which suggests a reduction in the resorpo sodium and water.

Adenosine Triphosphatases↗
PubMed1978

Incidence of spontaneous ileocecal immunocytomas in hybrids of LOU/C rats and rat strains with low spontaneous tumor incidence.

Monoclonal immunoglobulin-secreting tumors (immunocytomas or plasmacytomas) appear in many species, but they occur at a low incidence and usually originate in lymphoid tissues. However, in the rat, the incidence of malignant spontaneous immunocytomas (or plasmacytomas) was high and the tumors consistently arose in the ileocecal lymph nodes. In inbred LOU/C/Wsl rats, these immunocytomas developed in twice as many males (31%) as females (16%). The susceptibility of the rats to immunocytoma was under genetic control; e.g., LOU/C/Wsl rats had a dominant locus (or loci) of susceptibility that could induce immunocytoma in inbred AUG/Wsl or inbred A X C9935/Wsl rats. However, inbred Okamoto/Wsl rats had at least one dominant locus of resistance that did not exist in LOU/C/Wsl, LOU/M/Wsl, AUG/Wsl, or A X C9935/Wsl rats.

Animals↗
PubMed1976

Immunological enhancement of rat renal allografts using rabbit antisera with specificity for rat transplantation antigens.

Rabbits immunized with particulate and soluble preparations of rat lymphoid tissue of the HO strain produced antisera which reacted without strain specificity on rat lymphocytes. Absorption of the sera with tissue from the AS strain of rat removed the antibodies reacting with AS tissue leaving activity against HO cells only. Studies with backcross rats showed that the antigens detected by these sera were products of the AgB genes or genes segragating with them. The immunosuppressive activity of rabbit antisera specific for Ag-B5 rat transplantation antigens was tested in a rat renal allograft assay. Some of the antisera markedly prolonged the survival of (AS X HO)F1 kidneys transplanted to AS rats. The prolongation of graft survival was not due to ALS activity since the sera were active in the absence of antibody directed against recipient antigens. There was no correlation between in vivo enhancement and anti-donor lymphocytotoxic titres of the xenoantisera.

Absorption↗
PubMed1979

Segregation of rat chromosomes in somatic cell hybrids between rat cells and HT 1080 human fibrosarcoma cells.

We produced somatic cell hybrids between HT 1080-6TG human fibrosarcoma cells and either rat white blood cells (WBC) or cells directly derived from rat spleen. Karyologic and isozyme analyses of hybrid cells indicated that they preferentially lose rat chromosomes. Hypoxanthine-aminopterine thymidine-selected hybrid clones expressing rat hypoxanthine phosphoribosyltransferase (HPRT), glucose-6-phosphate dehydrogenase (G6PD), and phosphoglycerate kinase (PGK) and containing the rat X chromosome were counterselected in a medium containing 30 micrograms/ml of 6-thioguanine. Concordant loss of the rat X chromosome and of the expression of rat HPRT and G6PD was observed in the hybrid clones.

Animals↗