Showing papers on "In vivo published in 1972"

Tumor dormancy in vivo by prevention of neovascularization.

Abstract: Dormant solid tumors were produced in vivo by prevention of neovascularization. When small fragments of anaplastic Brown-Pearce carcinoma were implanted directly on the iris in susceptible rabbits, they always vascularized. A characteristic growth pattern, consisting of prevascular, vascular, and late phases, was observed, which terminated with destruction of the eye within 2 wk. The beginning of exponential volume increase was shown to coincide with vascularization of the implant, as demonstrated by perfusion with intravenous fluorescein and by histologic sections. In contrast, implants placed in the anterior chamber, at a distance from the iris, did not become vascularized. After initial growth into spheroids, they remained arrested at a small size comparable to prevascular iris implants, for periods as long as 6 wk. Although dormant in terms of expansion, these avascular tumors contained a population of viable and mitotically active tumor cells. When reimplanted on the iris, vascularization was followed by rapid, invasive growth. These observations suggest that neovascularization is a necessary condition for malignant growth of a solid tumor. When a small mass of tumor cells is prevented from eliciting new vessel ingrowth from surrounding host tissues, population dormancy results. These data suggest that the specific blockade of tumor-induced angiogenesis may be an effective means of controlling neoplastic growth.

Stereochemistry of intercalation: interaction of daunomycin with DNA.

Abstract: DAUNOMYCIN1–3, a glycosidic anthracycline antibiotic from Streptomyces peucetius4, is being used in the treatment of acute leukaemia and solid tumours in man5,6. The biological activity seems to be due to complex formation with the DNA of deoxyribonucleoprotein4. In vivo, daunomycin inhibits both RNA and DNA synthesis7,8 and, in vitro, DNA-dependent RNA polymerase and DNA polymerase7–9.

Evidence that the bone resorption-stimulating factor produced by mouse fibrosarcoma cells is prostaglandin e2 : a new model for the hypercalcemia of cancer

Abstract: A transplantable mouse fibrosarcoma, HSDM1, produces a potent bone resorption-stimulating factor. The factor can be extracted from the tumor tissue and harvested from the medium of clonal strains of HSDM1 tumor cells growing in monolayer culture. It has several chemical and biological properties of a prostaglandin. Using radioimmunoassay techniques, we have shown that HSDM1 cells synthesize and secrete large quantities of prostaglandin E2 (PGE2). The specific bone resorption-stimulating activity of the HSDM1 factor extracted from the tumor is high and approximately equal to that of PGE2 as measured in a bone tissue culture system in vitro. Indomethacin, a potent inhibitor of PGE2 synthesis in HSDM1 cells, also inhibits production by the cells of the bone resorption-stimulating factor, and has no detectable nonspecific effects on the bone culture assay system. Mice bearing the HSDM1 tumor have higher levels of both calcium and PGE2 in serum than control mice. We conclude that PGE2 is the bone resorption-stimulating factor produced by HSDM1 tumor cells, and that secretion of PGE2 by the tumor in vivo accounts for the relative hypercalcemia observed in tumor-bearing animals. The HSDM1 tumor cell system constitutes a new model for studying the pathogenesis of hypercalcemia associated with certain malignant tumors.

Mechanism of the antitumour effect of interferon in mice.

Abstract: REPEATED inoculation of mouse interferon preparations inhibits the growth of several murine transplantable tumours and increases the survival of tumour inoculated mice1–6. The mechanism of this antitumour action of interferon in vivo is unknown. Since comparable interferon preparations inhibited the division of murine leukaemia L 1210 and Ehrlich ascites (EA) cells in suspension cultures7–9 it is possible that interferon also acts in vivo by inhibiting tumour cell multiplication. It is also possible, however, that interferon enhances in some manner the capacity of the host to reject the transplanted tumour.

Effect of Cholera Enterotoxin on Ion Transport across Isolated Ileal Mucosa

Abstract: The effects of cholera enterotoxin on intestinal ion transport were examined in vitro. Addition of dialyzed filtrate of Vibrio cholerae (crude toxin) to the luminal side of isolated rabbit ileal mucosa caused a delayed and gradually progressive increase in transmural electric potential difference (PD) and shortcircuit current (SCC). A similar pattern was observed upon addition of a highly purified preparation of cholera toxin, although the changes in PD and SCC were smaller. Na and Cl fluxes across the short-circuited mucosa were determined with radioisotopes 3-4 hr after addition of crude toxin or at a comparable time in control tissues. The toxin caused a net secretory flux of Cl and reduced to zero the net absorptive flux of Na. Similar flux changes were observed when either crude or purified toxin was added in vivo and tissues were mounted in vitro 3-4 hr later. Additon of D-glucose to the luminal side of toxin-treated mucosa produced a large net absorptive flux of Na without altering the net Cl and residual ion fluxes. Adenosine 3',5'-cyclic phosphate (cyclic AMP) and theophylline had previously been shown to cause a rapid increase in SCC and ion flux changes similar to those induced by cholera toxin. Pretreatment of ileal mucosa with either crude or purified cholera toxin greatly reduced the SCC response to theophylline and dibutyryl cyclic AMP, which, together with the flux data, suggest that both cyclic AMP and cholera toxin stimulate active secretion by a common pathway. Inhibition of the SCC response to theophylline was observed after luminal but not after serosal addition of toxin. In vitro effects of cholera toxin correlated closely with in vivo effects: heating toxin destroyed both; two V. cholerae filtrates which were inactive in vivo proved also to be inactive in vitro; PD and volume flow measurements in isolated, in vivo ileal loops of rabbit revealed that the PD pattern after addition of toxin is similar to that seen in vitro and also correlates closely with changes in fluid movement. The results suggest that stimulation by cholera toxin of a cyclic AMP-dependent active secretory process of the intestinal epithelial cells is a major cause of fluid loss in cholera.

Effect of Isoniazid on the In Vivo Mycolic Acid Synthesis, Cell Growth, and Viability of Mycobacterium tuberculosis

Abstract: When an actively growing culture of the H37Ra strain of Mycobacterium tuberculosis was exposed to isoniazid at a concentration of 0.5 μg/ml, the cells began to lose their ability to synthesize mycolic acids immediately. After 60 min, the cells had completely lost this ability. The synthesis of the three mycolate components—α-mycolate, methoxymycolate, and β-mycolate—was inhibited. The viability of the isoniazid-treated cells was unaffected up to about 60 min of exposure, after which time there was a gradual decline in the viability to about 18% after 180 min. Correspondingly, growth of the drug-treated cells slowed down and stopped after 24 hr. The inhibition of the synthesis of mycolic acids was reversible if the drug was removed before the loss of viability set in. Incubation of the viable cells in the absence of the drug for 24 hr restored the mycolate synthesis. These results strongly suggest that the inhibition of the synthesis of the mycolic acids is closely associated with the primary mechanism of action of isoniazid on the tubercle bacilli. The sequence of events which leads to the loss of viability of cells exposed to isoniazid is described.

The preparation and specificity of antibody to thyrotropin releasing hormone.

Abstract: Synthetic thyrotropin releasing hormone (L-pyroglutamyl-L-histidyl-L-prolineamide) (TRH) was coupled to bovine serum albumin (BSA) with bis-diazotized benzidine (BDB). Recovery after dialysis of 14C-TRH included in the reaction mixture indicated that the product contained 37.5 μg TRH/mg albumin. The TRH-BDBBSA conjugate in doses calculated to contain 200 and 1000 ng TRH was biologically inactive whereas 20 ng TRH significantly increased rat serum TSH in vivo. Immunization of rabbits with the conjugate yielded significant quantities of anti- TRH antibody which was detected by reaction of diluted antiserum with 125I-TRH. Using 125I-TRH a double antibody radioimmunoassay for TRH has been developed in which as little as 0.1 ng unlabeled TRH can be detected. A variety of TRH analogues were tested and all had little reactivity in this immunoassay. The most potent of these was L-pyroglutamyl-D-histidyl-L-prolineamide which had 1.08% of the activity of TRH. Addition of the amino acid constituents of TRH, various ...

Perspectives in nonsteroidal anti-inflammatory agents.

Abstract: Among numerous nonsteroidal anti-imflammatory agents synthesized in the past few years, various analogs of indomethacin, phenylacetic acid and heteroarylacetic acid have reached the stage of clinical evaluation. Their biochemical mechanisms of action are exemplified by the broad activity profile of indomethacin which includes inhibition of mediators and enzymes, effects on cell membranes, and, most recently, inhibition of prostaglandin biosynthesis. The importance of pharmacodynamic properties to clinical efficacy was clearly demonstrated in some cases. Several candidates were eliminated because of their side-effects. A group of α-methylarylacetic acids showed a high degree of stereospecificity in their potency and metabolisms in vivo, as well as inhibition of prostaglandin synthetase and albumin binding in vitro. Extrinsic Cotton effect provides a sensitive technique in the study of interactions of these drugs with biopolymers. Competitive binding and antagonistic interactions between nonsteroidal drugs, particularly salicylate, were observed in vitro and in vivo. Progress in salicylate research was marked by the synthesis of flufenisal as a new derivative with enhanced potency and longer duration of action. Several fenamate analogs and new chemical types have shown promise in preliminary clinical trials. Various immunological approaches are under investigation for the treatment of rheumatoid arthritis. Newer concepts are still needed to achieve more effective control of arthritic disorders.

Histamine formation in rat brain in vivo: effects of histidine loads.

Abstract: — Administration of l-histidine at the rate of 500 mg/kg induced an increase of nearly 50 per cent in the level of histamine in rat brain which lasted several hours. The augmentation of histamine level was not significant 3 h after lower doses or after d-histidine α-methyl DOPA and Ro 4-4602 neither affected the cerebral level of histamine nor its elevation induced by l-histidine. Brocresine, a known histidine decarboxylase inhibitor not only prevented the effect of histidine load but also induced a prompt fall in the amine level. These results confirm those from earlier experiments in vitro indicating that histamine synthesis in rat brain depends on a specific decarboxylase (EC 4, 1.1.22) which is not normally saturated by the endogenous level of its substrate. When histamine levels were enhanced by histidine treatment, histidine decarboxylase activity, as evaluated on hypothalamus homogenates, was significantly reduced; intracisternal administration of cycloheximide, an inhibitor of protein synthesis, had similar effects. On the other hand, enzyme activity was not altered by the addition of histamine to hypothalamus homogenates. These results are compatible with the existence of a regulation mechanism of histidine decarboxylase involving repression by its end-product.

Laser Inhibition of Dental Caries Suggested by First Tests in Vivo

Abstract: Intact tooth enamel from humans was exposed extraorally to a superpulsed, carbon-dioxide laser at energy densities of 10 to 15 joules/cm 2 . When it was tested in the mouth of one of the investigators, the lased enamel proved much more resistant than unlased control enamel to the oral environmental influences generally conducive to dental caries.

Immunological tolerance in bone marrow-derived lymphocytes i. evidence for an intracellular mechanism of inactivation of hapten-specific precursors of antibody-forming cells

Abstract: Administration of the 2,4-dinitrophenyl (DNP) derivative of the copolymer of D-glutamic acid and D-lysine (D-GL) to inbred mice induces a state of DNP-specific tolerance in such animals irrespective of their immune status at the time of treatment. Taking advantage of the relative ease with which DNP-D-GL can induce tolerance in an animal previously primed with an immunogenic DNP-carrier conjugate, we have established conditions for tolerance induction in an adoptive cell transfer system. Thus, the adoptive secondary anti-DNP antibody response of DNP-keyhole limpet hemocyanin (KLH)-primed spleen cells was completely, or almost completely, abolished by exposure of such cells to DMP-D-GL either in vivo or in vitro. Tolerance induction in vivo occurred irrespective of whether the DNP-primed cells were exposed to DNP-D-GL in the donor animal before adoptive transfer or in recipient mice after transfer. In the latter situation, it was possible to show that tolerance induction in this model occurs very rapidly (1 hr) and with relatively low doses of tolerogen (50 µg). Incubation of DNP-KLH-primed cells with DNP-D-GL in vitro under varying culture conditions also resulted in depression of the adoptive secondary response of such cells, although the kinetics and degree of tolerance induction in this way were slightly different from that obtained by in vivo tolerization. Utilizing the adoptive transfer tolerance system, it was possible to approach certain questions concerning the mechanism of tolerance induction and fate of tolerant bone marrow-derived (B) lymphocytes in the DNP-D-GL model. The possibility that suppression of anti-DNP antibody from the DNP-D-GL reflects blocking of surface receptor molecules on B lymphocytes has been ruled out by several experimental observations. The most conclusive evidence on this point derives from the failure of enzymatic treatment with trypsin to reverse the tolerant state induced by in vitro exposure of primed cells to DNP-D-GL, whereas trypsinization completely restored the immunocompetence of DNP-KLH-primed cells rendered unresponsive by exposure to DNP-ovalbumin in vitro. The present studies also demonstrate that the tolerant state induced by DNP-D-GL represents a predominantly irreversible inactivation of specific B lymphocytes. This conclusion is derived from experiments in which it was found that tolerance was maintained through as many as two serial adoptive transfers performed over a period of time of at least 24 days from the single exposure of such cells to the tolerogen. Moreover, the possibility that maintenance of tolerance through such serial transfers was due to inadvertent transfer of tolerogenic doses of DNP-D-GL was definitively ruled out. It appears, therefore, that DNP-specific tolerance induced by DNP-D-GL is an example of irreversible inhibition of cell reactivity to antigen reflecting yet-to-be-determined events at the intra- and subcellular levels.

Growth Kinetics of Diethylnitrosamine-induced, Enzyme-deficient “Preneoplastic” Liver Cell Populations in Vivo and in Vitro

Abstract: Summary Rats fed 5 mg diethylnitrosamine per kg per day die from hepatocellular carcinoma after 138.0 ± 10.7 days (n = 258). Thirty days after start of feeding, circumscribed areas of deficiencies of glucose 6-phosphatase and adenosine triphosphatase appear in the enzyme histochemical preparation of the liver. The number of enzyme-deficient areas increases approximately exponentially until the 70th day, after which it remains stationary. By grouping the enzyme-deficient areas of the liver sections in 54 classes according to size as measured by planimetry (increment per class, 0.0584 sq mm) as a function of time, it can be seen that only areas of Class 1 to 8 (0.0584 to 0.467 sq mm) are present until the 80th day. Thereafter the number of larger areas up to Class 54 (3.154 sq mm) increases discontinually. In autoradiograms prepared after seven injections of thymidine-3H at 6-hr intervals, at early stages the labeling index of hepatocytes of enzyme-deficient areas is not significantly different from the surrounding parenchyma. From the 90th day onward, however, it is greatly increased in individual enzyme-deficient areas, while others maintain a low labeling index. Hepatocytes from nodular enzyme-deficient portions of liver tissue of diethylnitrosamine-fed rats proliferate in vitro, in contrast to those of normal adult liver of control rats. The thymidine-3H labeling index of these cultured hepatocytes 30 min after addition of thymidine-3H differs by a factor of about 25 between individual liver explants of diethylnitrosamine-fed rats under standardized culture conditions. Foci of enhanced proliferation are seen within slowly proliferating hepatocytes. From the varying behavior of the enzyme-deficient cell populations as demonstrated in vivo and in vitro, it is concluded that they are not a homogeneous preneoplastic population but rather potentially preneoplastic cells in various stages of development. Rapidly proliferating subpopulations of the enzyme-deficient cell groups might be foci of origin of hepatocellular carcinomas.

Clinical and pharmacological studies with 5-hydroxy-2-formylpyridine thiosemicarbazone.

Abstract: Summary 5-Hydroxy-2-formylpyridine thiosemicarbazone (5-HP) is the first of a relatively new class of antineoplastic agents, the α-( N )-heterocyclic carboxaldehyde thiosemicarbazones, to be studied in man. This study characterizes the toxicity and pharmacological disposition of the drug in 13 patients. Plasma levels of 5-HP decayed in biphasic mode with an initial half-life of 2.5 to 10.5 min. Of the administered dose, 47 to 75% was excreted within 24 hr, and the major metabolites (50 to 74% or urinary radioactivity) were glucuronide conjugates. A characteristically dark green urine resulted from the excretion of significant amounts of iron (2 to 11 mg/24 hr) in chelate form with 5-HP. The incorporation of thymidine- 3 H into DNA was inhibited in isolated normal and leukemic leukocyte suspensions after exposure in vitro and in vivo to 5-HP. Transient decreases in blast counts were observed in three of five patients with acute leukemia, although no remissions were obtained. No antitumor effects were noted in eight patients with solid tumors. Administration of larger doses of drug was limited by gastrointestinal toxicity. Mild myelosuppressant effects and hemolysis were noted in five patients treated with 5-day courses of drug. While toxicity appears to limit the usefulness of this compound as an antineoplastic agent, antileukemic activity was shown, and studies of other members of this class of agents are warranted.

In vivo Studies on the Release of Hormones from the Corpora Cardiaca of Locusts

Abstract: Sectioning of the afferent nerves (NCCl and NCCll) to the locust corpus cardiacum prevents thein vivo release of adipokinetic hormone from the glandular lobes. This failure to release the hormone during flight and the consequent lack of lipid mobilisation brings about an impairment of flight performance which can be corrected by injections of corpus cardiacum extracts. Sectioning of the NCCl and NCCll reduces markedly the activity of the corpora allata. However, the poor flight performance of allatectomised locusts is not related to an inability to mobilise lipid since injections of corpus cardiacum extract which will mobilise fat body lipid in these locusts have no effect on flight performance. The results of individual sectioning of the NCCl and NCCll suggest that a double innervation of the glandular lobes functionsin vivo to control adipokinetic hormone release but that the NCCl alone may control the release of the diuretic hormone.

The effect of L-tryptophan and some psychotropic drugs on the formation of 5-hydroxytryptophan in the mouse brain in vivo

Abstract: L-Tryptophan and various agents known to interfere with the brain monoamines were injected intraperitoneally to mice. Subsequently, the accumulation of 5-hydroxytryptophan (5-HTP) in the brain induced by the intraperitoneal injection of the decarboxylase inhibitor Ro 4-4602 was investigated. Also the tryptophan, 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels in the brain were measured.

Dissociation of MIF Production and Cell Proliferation

Abstract: The principal methods currently employed to explore the mechanism of cell-mediated immunity are blast cell transformation, production of soluble mediators and direct lymphocyte-target cell cytotoxicity. It is important to understand the nature of the cell detected in each of these assays in vitro , and to establish its relationship to the cell-mediated response in vivo . While it appears clear that the induction phase in sensitization requires the proliferation of stem cells to fully competent lymphocytes, there is considerable evidence in vivo to suggest that the effector arm of the response does not require cell proliferation. The most obvious example in vivo of this is the well known radiation resistance of the cell-mediated immune response in comparison to the humoral responses (1, 2). Additionally, cells treated with mitomycin C, under conditions in which they can synthesize some RNA and protein but cannot divide, are capable of effecting passive transfer (3).

Comparative Activity of Sisomicin, Gentamicin, Kanamycin, and Tobramycin

Abstract: Gentamicin, sisomicin, tobramycin, and kanamycin were compared in parallel tests in vitro and in vivo against a variety of bacterial strains and species A number of differences were seen in vitro, in particular: (i) the lower activity of kanamycin, (ii) the greater activity of tobramycin against Pseudomonas, (iii) the greater activity of gentamicin and sisomicin against Serratia, and (iv) the generally similar results with tobramycin, gentamicin, and sisomicin against species other than Pseudomonas and Serratia, with the ranking in order of decreasing activity being sisomicin, gentamicin, and tobramycin Analysis of disc test results suggested that the gentamicin disc is not adequate for testing the susceptibility of all bacteria to sisomicin or tobramycin In vivo tests did not confirm all specifics of in vitro tests; results of in vivo tests indicated that sisomicin may be the most active It is suggested that the place of each of the antibiotics in human therapy can best be evaluated by more rigorous in vivo tests and clinical studies rather than extensive in vitro comparisons

Comparison of in vitro and in vivo assays for nitrate reductase in soybean leaves

Abstract: Difficulties encountered in measuring nitrate reductase activity in soybean leaves (Glycine max [L.] Merr.) using published methods for extraction and in vitro assays attracted our attention to an in vivo assay first published by Mulder et al. (7) and recently refined by Randall (8). We have made minor improvements in both the in vivo and in vitro assays and have attempted to determine if a reproducible relationship exists between the two assays.

Analysis by Gas Chromatography of Amines and Nitrosamines Produced In Vivo and In Vitro by Proteus mirabilis

Abstract: Reproducible procedures suitable for routine analysis of small quantities of body fluids and culture media were developed by use of gas-liquid chromatography, heptafluorobutyric-anhydride derivatives, and electron-capture detectors. Proteus mirabilis was isolated from two clinical cases of bacteriuria, and the alkalineextractable products elaborated by this organism in vivo were compared with those produced in vitro. N-nitrosodimethylamine, a potent carcinogen, was produced along with other amines by P. mirabilis in all urines tested (both in vivo and in vitro) and in cooked-meat medium. This compound was not produced in vitro by a strain of Escherichia coli tested on the same substrates. The significance of these findings was evaluated, with emphasis on the carcinogenic activity and toxicity of N-nitrosodimethylamine and on the use of gas-liquid chromatography as a tool for the diagnosis of urinary-tract disease.

Cellular immunoabsorbents in transplantation immunity specific in vitro deletion and recovery of mouse lymphoid cells sensitized against allogeneic tumors

Abstract: Mouse lymphoid cells, sensitized against tumor allografts, can be deprived of the immunoreactive cells by in vitro absorption with specific fibroblast monolayers. Populations of lymphocytes so depleted are less effective in retarding tumor growth in vivo and in lysing tumor cells in vitro. Moreover, the adsorbed immunoreactive cells can be recovered specifically and are subsequently efficient in inhibiting tumor growth in vivo and in killing tumor cells in vitro. Further evidence is presented for the suggestion that the destruction of target cells in vitro by sensitized lymphoid cells is truly representative of the mode of destruction of grafted cells in vivo.