Showing papers on "Intraperitoneal injection published in 1996"

Central administration of GLP-1-(7-36) amide inhibits food and water intake in rats

Abstract: Glucagon-like peptide (GLP)-1-(7-36) amide and its pancreatic receptors are important for control of blood glucose levels. However, rat GLP-1 receptors are also localized in the brain, in hypothalamus, and in areas without a blood-brain barrier. When rats were kept on a food restriction schedule, intracerebroventricular injection of GLP-1 just before food was offered inhibited food intake. However, peripheral GLP-1 administration by intraperitoneal injection had little effect. GLP-1 effects on water intake and output were also investigated. Intracerebroventricular GLP-1 profoundly inhibited angiotensin II-induced drinking behavior in rats, and water intake was suppressed by exogenous GLP-1 in rats habituated to a water restriction schedule. These effects were reproduced by intraperitoneal administration of GLP-1. Furthermore, intracerebroventricular GLP-1 stimulated urinary excretion of water and sodium. The centrally elicited effects were blocked by the GLP-1 antagonist exendin-(9-39) amide, whereas the N-terminally extended and inactive GLP-1-(1-36) amide had no effect on feeding and drinking. GLP-1 had no effect in behavioral assays measuring exploratory locomotor activity and conditioned taste aversion. In conclusion, GLP-1 may play a physiological role in regulation of both ingestion and the water and salt homeostasis.

Beta-cell apoptosis is responsible for the development of iddm in the multiple low-dose streptozotocin model

Abstract: Although insulin-dependent diabetes mellitus (IDDM) results from irreversible loss of beta cells, the mode of cell death responsible for this loss has not previously been categorized. In this study, the multiple low-dose streptozotocin (stz) model (intraperitoneal injection of stz at a concentration of 40 mg/kg body weight per day for five consecutive days) was used to investigate beta-cell death during the development of IDDM in male C57B1/6 mice. Apoptotic cells were evident by light microscopy within the islets of Langerhans of treated animals from day 2 (the day of the second stz injection) until day 17. Immunohistochemical localization of insulin to the dying cells confirmed the beta-cell origin of the apoptosis. Two peaks in the incidence of beta-cell apoptosis occurred: the first at day 5, which corresponded to an increase in blood glucose concentration, and the second at day 11, when lymphocytic infiltration of the islets (insulitis) was maximal. Insulitis did not begin until day 9, by which time treated animals had developed overt diabetes as revealed by blood glucose and pancreatic immunoreactive insulin (IRI) measurements. Beta-cell apoptosis preceded the appearance of T-cells in the islets and continued throughout the period of insulitis. Thus, whether induced by stz or a subsequent immune response, apoptosis is the mode of cell death responsible for beta-cell loss in the multiple low-dose stz model of IDDM.

Middle-sized molecule fractions isolated from uremic ultrafiltrate and normal urine inhibit ingestive behavior in the rat.

Abstract: Uremic patients with suppressed food intake may regain appetite soon after starting dialysis, presumably because of the removal of one or more toxic factors that suppress appetite. To investigate this matter, this study used a new experimental model in free-moving, unstressed male Wistar rats (300 to 350 g) with feeding catheters channeled from the top of the skull to the oral cavity. When the rats recovered from surgery, they were tested under standardized conditions by being given an intraoral infusion (1 mL/min) of a 1 M sucrose solution or a 97 g/L protein solution or a mixed solution of carbohydrate, protein, and fat (Fortimel (Nutricia Nordica AB, Stockholm, Sweden)) while the time (volume) of ingestion was recorded. Solutions to be tested for their ability to inhibit ingestion were injected intraperitoneally (lp) and the intraoral infusion was started 20 min later. Plasma ultrafiltrate was collected from end-stage renal failure patients by isolated ultrafiltration at the beginning of their first hemodialysis and pooled. Ultrafiltrate was also obtained by filtering pooled plasma from healthy volunteers in vitro, using the same type of dialyzer and cellulose acetate membranes as those used in the uremic patients. Morning urine samples from healthy volunteers were pooled and subjected to the same in vitro filtration procedure as the normal plasma. Intraperitoneal injection of 20 mL normal ultrafiltrate had no effect on sucrose ingestion, whereas injection of 20 mL uremic ultrafiltrate reduced the ingestion of sucrose solution by 23% and the ingestion of Fortimel by 17%. Ten mL of ultrafiltrate from normal urine reduced the sucrose intake by 42%. The pooled ultrafiltrates from normal and uremic plasma and normal urine were subjected to molecular filtrations using a series of membranes with known cut-off points. The filtrations yielded four concentrated fractions with molecular weight ranges of 0.1 to 0.5 kilodaltons (kd), 0.5 to 1 kd, 1 to 5 kd, and 5 to 10 kd, respectively; the plasma fractions were concentrated a factor of about 25:1 and the urine fractions by about 15:1. After an ip injection of 2 mL of each concentrated plasma fraction, only the 1 to 5 kd fraction from the uremic ultrafiltrate inhibited sucrose intake, whereas the corresponding fraction from the normal ultrafiltrate had no effect. After injection of 1, 3, and 5 mL of the concentrated fractions of uremic ultrafiltrate, a dose-dependent inhibition of sucrose intake was achieved with the 1 to 5 kd fraction and, to a lesser extent, with the 5 to 10 kd fraction. Intraperitoneal injection of 0.5, 1.0, and 2 mL of the concentrated 1 to 5 kd fraction, but not of the other fractions from normal urine, also resulted in a dose-dependent inhibition of sucrose intake. The 1 to 5 kd fractions from the uremic ultrafiltrate and the normal urine ultrafiltrate also inhibited protein intake in a dose-dependent manner. These results suggest that one or more toxic compounds in the middle-molecule weight range, which are normally excreted in the urine, accumulate in uremia and suppress food intake.

Induction of central tolerance by intrathymic inoculation of adenoviral antigens into the host thymus permits long-term gene therapy in gunn rats

Abstract: Recombinant adenoviruses are highly efficient at transferring foreign genes in vivo. However, duration of gene expression is limited by the host antiviral immune response which precludes expression upon viral readministration. We tested the feasibility of prolonging gene expression by induction of central tolerance to adenoviral antigens in bilirubin-UDP-glucuronosyltransferase-1 (BUGT1)-deficient Gunn rats. Tolerance was induced by intraperitoneal injection of antilymphocyte serum, followed by intrathymic inoculation of one of the following: a recombinant adenovirus (Ad), adenovirus human UDP-glucuronosyltransferase (Ad-hBUGT1) carrying the hBUGT1 gene; a protein extract of the same virus; or viral infected hepatocytes. Controls received intrathymic injections of normal saline. After 12 d all groups were injected intravenously with 5 x 10(9) pfu of either Ad-hBUGT1 or adenovirus beta-galactosidase (Ad-LacZ) (expressing the Escherichia coli beta-galactosidase [LacZ] gene). In all three groups of tolerized rats, hBUGT1 was expressed in the liver after administration of Ad-hBUGT1, with glucuronidation of biliary bilirubin of above 95%. Serum bilirubin levels decreased from 7.2 to 1.8 mg/dl within 1 wk and remained low for 7 wk. Similar findings were observed following repeat injections given on days 45 and 112. In control rats serum bilirubin levels were reduced for only 4 wk, and viral readministration was ineffective. In all tolerized groups, but not in controls, there was a marked inhibition of appearance of neutralizing antibodies and cytotoxic lymphocytes against the recombinant adenovirus. Injection of wild type adenovirus-5 (Ad5) into the tolerized rats elicited a wild type-specific cytotoxic lymphocyte response. This is the first demonstration of Ad-directed long-term correction of an inherited metabolic disease following central tolerization with thymic antigen.

Migratory responses of PMN after intraperitoneal and intratracheal administration of lipopolysaccharide

Abstract: The present study was undertaken primarily to investigate accumulation of polymorphonuclear leukocytes (PMN) within the lung vasculature after intraperitoneal injection of lipopolysaccharide (LPS) and migratory responses of those intravascular PMN to intratracheally instilled LPS in mice Intraperitoneally injected LPS was absorbed into the blood rapidly, and the concentration of circulating LPS peaked at 1 h postinjection Tumor necrosis factor concentration in blood began to increase at 05 h and also peaked at 1 h postinjection The number of lung vascular-associated PMN was increased 75-fold at 05 h post-intraperitoneal injection However, neither diapedesis of PMN nor injury was observed in the lung, while mixed cell infiltration was observed in the liver Although intraperitoneally injected LPS caused a significant PMN accumulation within the lung vasculature, pre-intraperitoneal injection of LPS dramatically and dose dependently abolished both intratracheal LPS-inducible PMN infiltration and apparent plasma protein leakage into the alveolar space On the other hand, pre-intratracheal instillation of LPS enhanced rather than reduced intraperitoneal LPS-inducible PMN infiltration into the peritoneal cavity In rats, a sublethal dose of intraperitoneally injected LPS caused a modest increase in alveolar PMN and yet reduced intratracheal LPS-inducible robust transpulmonary PMN infiltration Although mechanisms of different migratory responses of the lung vasculature-associated PMN are unknown, the inhibitory effects of intraperitoneally injected LPS on transpulmonary PMN infiltration may be applicable to treatments for septic lung diseases

The histopathology of carp, Cyprinus carpio L., exposed to microcystins by gavage, immersion and intraperitoneal administration

Abstract: Carp liver, gills, intestine, kidneys, heart and spleen were studied by histology after the fish were exposed to microcystins by gavage, immersion and intraperitoneal administration. Intraperitoneal inoculation with microcystins caused necrosis or dose- dependent degeneration in the liver, gills and kidneys. Gavaging with microcystins caused changes in the histopathology of the liver and gills. Cellular degeneration and necrosis occurred in the liver, gills and kidneys when carp were introduced to a tank containing 1.7 μg ml−1 of microcystins. Lesions were not observed in the heart, spleen or intestines from any of the treated carp. Microcystins administered by intraperitoneal injection at a concentration of 50 μg kg−1 were lethal to all fish within 8 h, while gavaging with 250 μg kg−1 of microcystins caused minimal damage in the tissues studied.

Intravenous fumonisin B1 induces cell proliferation and apoptosis in the rat

Abstract: In the rat, the target organs of fumonisin B1, a mycotoxin produced by Fusarium moniliforme, are the kidney and liver. Fumonisin B1 is also hepatocarcinogenic in the rat and is associated epidemiologically with esophageal cancer in humans. We investigated the effect of a single intravenous dose of fumonisin B1 on cell proliferation, lesion development, and glutathione status in the major target organs of the rat. Male Sprague-Dawley rats were injected intravenously with fumonisin B1 at 0 or 1.25 mg/kg and were euthanized at 12 hr or, 1, 2, 3, or 5 days. An intraperitoneal injection of 5-bromo-2′-deoxyuridine at 100 mg/kg was given 90 min prior to euthanasia. In fumonisin B1 treated rats, serum cholesterol and serum urea nitrogen were elevated; however, the activity of hepatic enzymes was unaffected. Hepatic and renal glutathione concentrations were depressed at 12 and 24 hr, respectively, with subsequent recovery. Histologic changes were most prominent in the outer medulla of the kidney, with cell proliferation and apoptosis followed by nephrosis. Cell proliferation also occurred in the liver and esophagus, but in the absence of tissue injury. The labeling index peaked on day 1 for the liver and on day 3 for the esophagus. These results confirm that the primary target organ of fumonisin B1 in the rat is the kidney and support the concept that fumonisin B1-induced mitogenesis may be the mechanism of carcinogenesis.

Prevention of the development of immediate hypersensitivity and airway hyperresponsiveness following in vivo treatment with soluble IL-4 receptor.

Abstract: The effects of local versus systemic treatment with soluble IL-4 receptors (sIL-4R) were tested in a model of allergen-induced immediate hypersensitivity responses in BALB/c mice. Mice sensitized through the airways to ovalbumin (OVA) by ultrasonic nebulization once a week for 4 weeks developed increased serum anti-OVA IgE and IgG1 antibody titers and these were accompanied by immediate-type skin test responses to the allergen. These responses were also associated with the development of increased airway responsiveness (AR) as monitored by electrical field stimulation of tracheal smooth muscle preparations in vitro. Sensitized mice, treated by intraperitoneal injections of sIL-4R (150 μg/ injection) administered in parallel to the sensitization protocol, developed significant suppression of anti-OVA IgE, anti-OVA IgG1 antibody production and of immediate cutaneous hypersensitivity responses. Airway responsiveness was normalized to some extent. Total IgE production was only slightly reduced. These effects were comparable to the findings following intraperitoneal injection of monoclonal anti-IL-4 antibody. Administration of sIL-4R via the airways was also effective in inhibiting the development of immediate hypersensitivity responses, including IgE production, and was more potent in normalizing airway responsiveness. These effects were achieved at lower concentrations than needed for systemic treatment. These data suggest that delivery of sIL-4R via the airways can effectively modulate the development of immediate hypersensitivity and airway hyperresponsiveness in response to aerosolized allergen.

Administration of Purified Human Plasma Cholinesterase Protects Against Cocaine Toxicity in Mice

Abstract: Background: Cocaine is metabolized in part by plasma cholinesterase to form ecgonine methyl ester. Decreased plasma cholinesterase activity is associated with enhanced cocaine toxicity in both humans and animals. This study was designed to determine whether the administration of exogenous plasma cholinesterase is protective against cocaine toxicity. Methods: Using a blinded protocol, female Swiss albino mice were randomized to receive an intraperitoneal injection of either 13.7 mg/kg of purified human plasma cholinesterase dissolved in phosphate buffered saline, or an equal volume of phosphate buffered saline as a control. One hour later, all animals received an intraperitoneal injection of either 100 or 125 mg/kg of cocaine, and the incidence of seizures and death was recorded. In a similar fashion, another group of animals was randomized to receive a human plasma cholinesterase dose of either 13.7 or 27.4 mg/kg, followed by 150 mg/kg of cocaine. Results: Administration of 13.7 mg/kg of human plasma chol...

Essential fatty acid uptake and metabolism in the developing rodent brain.

Abstract: Studies were carried out to determine whether the brain takes up and metabolizes essential fatty acids during early postnatal development in rodents. Rats and mice were dosed with deuterium-labeled linoleic and linolenic acids either by intraperitoneal injection or by gavage. Animals were killed at different times thereafter, and organs were removed. Brains, livers, and blood were analyzed by gas chromatography--negative-ion-mass spectrometry for labeled fatty acids. To determine whether fatty acids were present in the brain apart from cerebral blood, a subset of animals was exsanguinated by perfusion with buffered saline, and the brain was then fractionated into subcellular components. Results demonstrated that the brain took up both labeled essential fatty acids within 8 h from the time of dosing. There was on average a greater uptake of linolenic acid into the cerebellum than into the cerebral cortex during the first 8 d of life in rats. The amount of linoleic acid taken into either region was similar, however. Docosahexaenoic acid intermediates, 20:5n-3 and 22:5n-3, were also found labeled in the brain. Time-course labeling experiments indicated that these intermediates may be converted to 22:6n-3 within the brain. A rise of labeled 22:6n-3 in the brain at 24 h appeared to be due to uptake of this fatty acid from the blood. The amount of labeled 22:6n-3 in the brain continued to increase beyond 24 h, and this did not appear to be correlated with its blood concentration. These results suggest that, during development in the rodent, different regions within the brain may vary in their capacity to synthesize 22:6n-3, and this may be correlated with regional growth rates.

The effects of microcystins on the serum biochemistry of carp, Cyprinus carpio L., when the toxins are administered by gavage, immersion and intraperitoneal routes

Abstract: Microcystins were administered to carp, Cyprinus carpio L., by intraperitoneal injection. Tests performed on the serum indicated liver and gill damage, and disturbances in hepatic and osmoregulatory functions. Exposure of carp to microcystins by gavage and inrimersion caused changes indicating mild liver damage and changes in the equilibrium of cationanion balance in some treatments. The results of gavage and immersion exposure indicate that acute roxicity is unlikely to occur in wild carp populations, but chronic poisoning may follow repeated sublethal exposure. A serum biochemical profile comprising alanine amino transferase, aspartate amino transferase, bile acids, bilirubin, sodium and chloride determinations may provide a useful diagnostic indication of microcystin poisoning in wild carp populations.

The immunomodulatory effect of laminaran [beta(1,3)-D-glucan] on Atlantic salmon, Salmo salar L., anterior kidney leucocytes after intraperitoneal, peroral and peranal administration

Abstract: Anterior kidney leucocytes obtained from Atlantic salmon, Salmo salar L., 2 days after administration of laminaran, were assayed for their capacity to reduce nitroblue tetrazolium to formazan, and for their activity of lysosomal acid phosphatase after intraperitoneal (15 mgkg−1), peroral (150 mg kg−1) or peranal (150 mg kg−1) administration. Leucocytes obtained from salmon treated by an intraperitoneal injection of laminaran produced significantly more superoxide anion than cells obtained from fish treated with dextran or sodium chloride immediately after cell isolation. Immediately after extraction, the activity of acid phosphatase in anterior kidney leucocytes obtained from salmon injected with laminaran was significantly higher than in cells harvested from fish treated with dextran or sodium chloride. Furthermore, cells obtained from salmon treated by peroral instillation of laminaran showed significantly enhanced production of superoxide anion compared with leucocytes from fish treated with either sodium chloride or dextran. The acid phosphatase activity in anterior kidney leucocytes from salmon treated by peroral and peranal instillation of laminaran was significantly higher than in cells from fish treated either with sodium chloride or dextran. Finally, fluorescence microscopic examination of tissue sections from fish treated peranally by intubation with fluorescein labelled laminaran revealed fluorescent vesicles in intestinal epithelial cells and in anterior kidney macrophages.

Retention of furunculosis vaccine components in Atlantic salmon, Salmo salar L., following different routes of vaccine administration

Abstract: The retention of vaccine components was studied in Atlantic salmon, Salmo salar L., following different routes of vaccination against Aeromonas salmonicida. Frozen tissue was collected from the spleen, head kidney, hind gut and liver of fish that had been vaccinated by intraperitoneal injection (monovalent and trivalent vaccines), immersion and oral administration 2,6,8 and 16 weeks previously. The trivalent injection group showed the highest levels of specific antibodies and was the only group to show protection following challenge with virulent A. salmonicida. Following intraperitoneal injection, there was an initial widespread distribution of Aeromonas lipo-polysaccharide, but by 16 weeks lipopolysaccharide was predominantly found in macrophage populations in the spleen, head kidney and abdominal granulomas. Only small amounts of lipopolysaccharide were retained in the head kidney of the immersion group and no lipopolysaccharide was retained in the oral group. Small and inconsistent amounts of A-layer protein were present in the meianomacrophages of the head kidney of all groups. The relative prominence of A-layer protein in the spleen of the trivalent injection group 8 weeks after vaccination was linked to the high levels of specific antibodies, and possible immune-complex trapping and the enhancement of immunological memory.

Biphasic, organ-specific, and strain-specific accumulation of platelets induced in mice by a lipopolysaccharide from Escherichia coli and its possible involvement in shock.

Abstract: Platelets contain a large amount of 5-hydroxytryptamine (5HT, serotonin). Intravenous injection into BALB/c mice of a Boivin's preparation of lipopolysaccharide (LPS) from Escherichia coli induced rapid 5HT accumulation in the lung (within 5 min) and slow 5HT accumulation in the liver (2 to 5 h later). The rapid response required high doses of LPS (more than 0.1 mg/kg). On the basis of 5HT measurements, 70% or more of the platelets which disappeared from the blood appeared to have accumulated rapidly in the lung, and a large number of platelets were found there by electron microscopy. A shock, which was manifested by crawling, convulsion, or prostration, followed shortly after the rapid accumulation of 5HT in the lung. On the other hand, the slow accumulation of 5HT in the liver could be induced by much lower doses of LPS (1 microg/kg or less), even when given by intraperitoneal injection. This 5HT accumulation appears to be a reflection of platelet accumulation in the liver (Y. Endo and M. Nakamura, Br. J. Pharmacol. 105:613-619, 1992). The combination of a low dose of LPS with D-galactosamine amplified the hepatic accumulation of 5HT, and the mice developed a severe hepatic congestion resulting in death. The rapid response was not induced at all in C3H/HeN mice. These results and comparison with other LPS preparations indicate that some component(s) of LPS from E. coli induces a biphasic, organ-specific and strain-specific accumulation of platelets, and it is proposed that this effect is involved in the development of shock.

Inducible Nitric Oxide Synthase and the Regulation of Central Vessel Caliber in the Fetal Rat

Abstract: Background The purpose of this study was to evaluate the possibility that inducible nitric oxide synthase (iNOS) regulates the fetal circulation. Methods and Results Positive evidence for iNOS gene expression was noted in heart central vessels and placenta of untreated rat fetuses. Rats in the last week of pregnancy were treated for 5 days with l-NG-(1-Iminoethyl)lysine (L-NIL), a selective inhibitor of iNOS, at 1, 10, and 100 μg/mL in the drinking water. To raise NO levels, lipopolysaccharide (LPS) 30 μg/kg was given by intraperitoneal injection, and sodium nitroprusside (SNP) was placed in mini-osmotic pumps to deliver 10 μg/kg per minute. Control animals were undisturbed. On day 21 of gestation, dams were anesthetized and fetuses were delivered by cesarean section and rapidly frozen in isopentane chilled in liquid nitrogen. Frozen sections (10 μm) were used to reconstruct a computer-generated three-dimensional image of the great vessels and ductus arteriosus. Significant constriction of the great vesse...

Chemopreventive Efficacy of Low Dose of Pravastatin, an HMG-CoA Reductase Inhibitor, on 1, 2-Dimethylhydrazine-Induced Colon Carcinogenesis in ICR Mice

Abstract: Potential chemopreventive action of de-escalated doses of pravastatin (Pr), an HMG-CoA reductase inhibitor, on 1,2-dimethylhydrazine.2HCl (DMH)-induced colon tumorigenesis was evaluated in ICR mice. Thirty mice each in 4 groups received an intraperitoneal injection of 20 mg DMH/kg body weight once weekly for 10 weeks, and were given drinking water dissolved Pr at the concentration of 10 ppm, 5 ppm, or 0 ppm (control) throughout the experiment. The incidence of colon tumors examined at week 35 was significantly lower in the Pr-treated groups than the control group: 20%. 21% and 23% vs. 55%. However, the tumor multiplicity/tumor-bearing animal was increased in the Pr-treated groups compared to the control group. Of all the tumors, 66 were adenocarcinomas in the distal colon and 5 were squamous cell carcinomas at the anus. The Pr treatment showed no hypocholesterolemic effect but did significant decrease of colonic mucosal cholesterol. The results seems to suggest that a small dose of Pr may reduce the incidence of colon cancers, perhaps being related, at least in part, to modulation of cholesterol synthesis in situ at the colonic mucosa.

Transforming growth factor-β in in vivo resistance

Abstract: The potential role of transforming growth factor-beta in in vivo resistance was examined by administration of transforming growth factor-beta-neutralizing antibodies to animals bearing the EMT-6/Parent tumor or the antitumor alkylating resistance tumors, EMT-6/CTX or EMT-6/CDDP. Treatment of tumor bearing animals with anti-TGF-beta antibodies by intraperitoneal injection daily on days 0-8 post-tumor cell implantation increased the sensitivity of the EMT-6/Parent tumor to cyclophosphamide (CTX) and cisplatin (CDDP) and markedly increased the sensitivity of the EMT-6/CTX tumor to CTX and the EMT6/CDDP tumor to CDDP, as determined by tumor cell survival assay. Bone marrow granulocyte-macrophage colony-forming units (CFU-GM) survival was determined from these same animals. The increase in the sensitivity in the tumors upon treatment with the anti-TGF-beta antibodies was also observed in increased sensitivity of the bone marrow CFU-GM to CTX and CDDP. Treatment of non-tumor-bearing animals with the anti-TGF-beta regimen did not alter blood ATP or serum glucose level but did decrease serum lactate levels. This treatment also decreased hepatic glutathione, glutathione S-transferase, glutathione reductase, and glutathione peroxidase in non-tumor bearing animals by 40-60% but increased hepatic cytochrome P450 reductase in these normal animals. Animals bearing the EMT-6/CTX and EMT-6/CDDP tumors had higher serum lactate levels than normal or EMT-6/Parent tumor-bearing animals; these were decreased by the anti-TGF-beta regimen. Treatment of animals bearing any of the three tumors with the anti-TGF-beta regimen decreased by 30-50% the activity of hepatic glutathione S-transferase and glutathione peroxidase, and increased by 35-80% the activity of hepatic cytochrome P450 reductase. In conclusion, treatment with transforming growth factor-beta-neutralizing antibodies restored drug sensitivity in the alkylating agent-resistant tumors, altering both the tumor and host metabolic states.

The venom of South American rattlesnakes inhibits macrophage functions and is endowed with anti-inflammatory properties.

Abstract: The injection of Crotalus durissus terrificus venom into the foot pad of mice did not induce a significant inflammatory response as evaluated by oedema formation, increased vascular permeability and cell migration. The subcutaneous injection of the venom, or its addition to cell cultures, had an inhibitory effect on the spreading and phagocytosis of resident macrophages, without affecting the viability of the cells. This effect was not observed when the venom was added to cultures of thioglycollate elicited macrophages, but it was able to inhibit these macrophage functions when the cells were obtained from animals injected simultaneously with the venom and thioglycollate. These observations suggest that the venom interferes with the mechanisms of macrophage activation. Leukocyte migration induced by intraperitoneal injection of thioglycollate was also inhibited by previous venom injection. This down-regulatory activity of the venom on macrophage functions could account for the mild inflammatory response observed in the site of the snake bite in Crotalus durissus terrificus envenomation in man.

Effect of intraperitoneal chemotherapy and fibrinolytic therapy on tumor implantation in wound sites.

Abstract: Failure of surgical treatment for gastrointestinal cancers is often caused by recurrence of the tumor in traumatized peritoneal surfaces. This study examined the effect of intraperitoneal administration of doxorubicin and recombinant tissue plasminogen activator (rt-PA), a fibrinolytic agent, on incidence and volume of postoperative tumor implants in peritoneal wounds. Prior to randomization, a surgical wound was created on the right parietal peritoneum of 110 BDIX rats and 6 × 105 DHD/K12 colon cancer cells were inoculated intraperitoneally (ip). The control group was given an intraperitoneal injection of saline. Five groups received 1 mg/kg of ip doxorubicin at different times postoperatively: at the end of surgery (DO), 3 hr after surgery (D + 3), postoperative day 1 (Dl), postoperative day 3 (D3), and postoperative day 7(D7). In a second set of experiments, five groups of rats received, in addition to postoperative doxorubicin, 5 mg/kg of intraoperative ip rt-PA. Incidence and volume of tumor implants in peritoneal wounds were assessed for each group 20 days after the tumor inoculation. All rats of the control group (incidence = 100%) developed tumor implants in peritoneal wounds. Mean (SD) volume was 16.2 (4.7) mm3. When administered at DO, D + 3, and Dl intraperitoneal doxorubicin reduced significantly the incidence and volume of tumor implants in wounds. Postoperative administration of doxorubicin at D3 and D7 did not affect significantly the incidence and the volume of tumor implants in peritoneal wounds. When rt-PA was administered intraoperatively, ip injection of doxorubicin at any postoperative timing decreased significantly the incidence and volume of tumor implants. In conclusion, ip doxorubicin administered before postoperative D3 may act on tumor cell implanted in peritoneal wounds. Delayed (D3, D7) ip administration of doxorubicin does not prevent the development of tumor implants in peritoneal wounds. Intraoperative administration of rt-PA may significantly increase the efficacy of delayed ip chemotherapy. © 1996 Wiley-Liss, Inc.

T-cell dysfunctions in hu-PBL-SCID mice infected with human immunodeficiency virus (HIV) shortly after reconstitution: in vivo effects of HIV on highly activated human immune cells.

Abstract: The state of activation of the immune system may be an important factor which renders a host more receptive to human immunodeficiency virus (HIV) and more vulnerable to its effects. To explore this issue with a practical in vivo model, we developed a modified protocol of HIV infection in hu-PBL-SCID mice. First, we assessed the time course of activation of human peripheral blood lymphocytes (hu-PBL) in the peritoneal cavity of SCID mice. At 2 to 24 h after the intraperitoneal injection into SCID mice, there was a clear-cut increase in the percentage of hu-PBL expressing early activation markers (CD69), concomitant with the release of soluble intercellular adhesion molecule-1 (sICAM-1) and the soluble interleukin-2 receptor (sIL-2R) and with the accumulation of mRNAs for a number of human cytokines. At 2 weeks, virtually all of the hu-PBL expressed the memory phenotype (CD45RO) and HLA-DR antigens as well. Cells collected from the SCID mouse peritoneum at 2 and 24 h after transplantation were fully susceptible to in vitro infection with HIV type 1 (HIV-1) in the absence of either IL-2 or mitogens. The injection of HIV into hu-PBL-SCID mice at 2 h after reconstitution resulted in a generalized and productive HIV infection of the xenochimeras. This early HIV-1 infection resulted in a dramatic depletion of human CD4+ cells and in decreased levels of sICAM-1 (in the peritoneal lavage fluid) as well as of sIL-2R and immunoglobulins M and A (in the serum). Enzyme-linked immunosorbent assay and/or reverse transcriptase PCR analysis showed higher levels of IL-4, IL-5, and IL-10 in the HIV-infected animals than in control hu-PBL-SCID mice, while gamma interferon levels in the two groups were comparable. When we compared the current model of HIV-1 infection at 2 weeks after the intraperitoneal injection of the hu-PBL in the SCID mice with the model described here, we found that the majority of immune dysfunctions induced in the 2-h infection of the xenochimeras are not inducible in the 2-week infection. This supports the concept that the state of activation of human cells at the moment of the in vivo infection with HIV-1 is a crucial factor in determining the immune derangement observed in AIDS patients. These results show that some immunological dysfunctions induced by HIV infection in AIDS patients can be mimicked in this xenochimeric model. Thus, the hu-PBL-SCID mouse model may be useful in exploring, in vivo, the relevance of hu-PBL activation and differentiation in HIV-1 infection and for testing therapeutic intervention directed towards either the virus or the immune system.

Macrophage Inflammatory Protein‐1β (MIP‐1β) Produced Endogenously in Brain During E. coli Fever in Rats

Abstract: Macrophage inflammatory protein-1 (MIP-1) evokes an intense fever, independent of a prostaglandin mechanism, and is now thought to play an important role in the defence response to bacterial pyrogens. The purpose of this study was 2-fold: (i) to determine whether the potent doublet of this cytokine, MIP-1beta, is actually produced in the brain in response to a pyrogenic dose of a lipopolysaccharide of Escherichia coli and (ii) to determine the anatomical site of synthesis of this cytokine in the brain. Following the intense fever produced by intraperitoneal administration of lipopolysaccharide in the unrestrained rat, MIP-1beta immunoreactivity was identified post mortem in two regions of the brain implicated in fever: the organum vasculosum laminae terminalis (OVLT) and the anterior hypothalamic, preoptic area (AH/POA). Microinjection of goat anti-mouse MIP-1beta antibody (anti-MIP-1beta) directly int the AH/POA markedly suppressed fever in rats in response to lipopolysaccharide. Further anti-MIP-1beta administered 180 min after the injection of lipopolysaccharide acted as an antipyretic and reversed the fever induced by the endotoxin. anti-MIP-1beta or control immunoglobulin G antibody microinjected into the hypothalamus immediately before the intraperitoneal injection of the control saline did not alter the temperature of the rats. Taken together, the present results demonstrate that MIP-1beta is produced in the brain in response to a bacterial endotoxin. These observations, in the light of earlier data on fever induced by MIP-1beta, further support the hypothesis that endogenously synthesized MIP-1beta acts as an intermediary factor in the evocation of fever by acting on the thermosensitive cells of the brain.

Induction of micronuclei by low doses of azidothymidine (AZT).

Abstract: The dideoxynucleoside azidothymidine (AZT; Zidovudine) was assessed for its ability to induce micronuclei in mouse erythrocytes at a low (therapeutic) dosage. Specifically, male and female BALB/c mice were treated via intraperitoneal injection 5 days a week for 2 weeks with saline or 17 mg AZT/kg body weight per day. Each animal was monitored for chemical-induced micronucleus formation over the course of the treatment regimen through the flow cytometric analysis of one-million pre-dosing and one million post-dosing peripheral blood erythrocytes. No significant change in micronucleus frequencies was observed for the vehicle control group as micronuclei continued to enter the peripheral blood pool at background levels. Conversely, the AZT-treated mice exhibited a statistically significant net increase in micronucleated cells over the course of dosing as erythrocytes with a high incidence of micronuclei entered the peripheral blood pool. The advantages of high throughout scoring protocols utilizing flow cytometry are discussed.