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Background —We investigated whether administration of a soluble recombinant P-selectin glycoprotein ligand-1 chimera (rPSGL-Ig) in conjunction with thrombolytic therapy would enhance thrombolysis by preventing ongoing interactions of leukocytes with platelets and the injured arterial wall. Methods and Results —An occlusive thrombus was formed in an internal iliac artery of Yorkshire pigs by placement of a copper coil in the artery under fluoroscopic guidance. Pigs then received heparin and, 15 minutes later, either vehicle or rPSGL-Ig followed by infusion with 25 mg tissue plasminogen activator according to the 90-minute regimen. Blood flow through the artery was monitored by angiography and scored on a scale of 0 to 3. Lysis of the thrombus was accelerated by 70% in pigs treated with rPSGL-Ig 250 μg/kg compared with control (13.3±5.0 versus 44.4±13.3 minutes; n=9 each). Eight of 9 control pigs reoccluded in 13.8±16.9 minutes after the end of tissue plasminogen activator infusion, whereas no reocclusion was observed in 8 of 9 pigs in the rPSGL-Ig group. When the dose of rPSGL-Ig was increased to 500 μg/kg, time to lysis was shortened by 61% from control (18.0±8.4 versus 46.0±8.9 minutes). Reocclusion occurred in 6.0±15.2 minutes in control but not in any rPSGL-Ig–treated pig (n=5 each). In addition, near-normal flow (score 2 or 3) after thrombolysis was achieved 59% and 58% faster in the 2 rPSGL-Ig groups than in their respective controls. Conclusions —Inhibition of leukocyte accumulation at the site of thrombosis with rPSGL-Ig may represent a safe therapeutic intervention that could be important in accelerating thrombolysis, achieving optimal reperfusion, and reducing incidence of acute reocclusion.

The therapeutic potential of recombinant human interleukin-11 (rhIL-11) was tested in a neutropenic rat model that mimics the clinical consequences of myelosuppressive chemotherapy complicated by Pseudomonas aeruginosa sepsis. rhIL-11-treated animals (150 micrograms/kg intravenously every 24 h for 3 days) had reduced endotoxin levels (P < .05) and less pulmonary edema fluid (P < .001) and were protected (P < .01) against thinning and necrosis of the intestinal mucosa compared with the control group. The survival rate in rhIL-11-treated animals was 40% (19/47), whereas it was 0 (0 of 19) in the control group (P < .01). The addition of ciprofloxacin (10 mg/kg every 12 h) resulted in a survival rate of 9 (60%) of 15, while the combination of rhIL-11 and ciprofloxacin resulted in 100% survival (15/15; P < .05). These results indicate that rhIL-11 supports mucous membrane integrity of the alimentary tract and decreases the systemic inflammatory response to experimental gram-negative infection in immunocompromised animals.

Publisher Summary This chapter discusses the cardiovascular and lymphoreticular systems of nonhuman primates and the pathophysiologic syndromes affecting specific areas of these systems. Major features of cardiovascular and lymphoreticular pathophysiology are described in the chapter using an anatomical approach. The clinical features of several disorders such as hematopoiesis, heart disorders, diseases of the great vessels, hypertension, and lymphangitis are also discussed in the chapter. Diseases of the great vessels include atherosclerosis, aneurysm, stroke, vasculitis, and thrombosis/emboli. The chapter discusses three types of hypertension: essential hypertension, renovascular hypertension, and pulmonary hypertension. The diseases of lymphoreticular system—peripheral lymphadenopathy and lymphangitis—are also discussed in the chapter. Nonhuman primates play a vital role in the research of transfusion medicine, blood storage research, and the related experimental studies that foster clinical and scientific data. Although transfusions and blood research are an obvious part of clinical medicine, nonhuman primates play an important role as animal models for certain human diseases.

Publisher Summary Macrophage colony-stimulating factor (M-CSF)—also known as CSF-1—is a hematopoietic growth factor that supports the survival, proliferation, and differentiation of cells of the monocyte lineage. M-CSF is produced in various cells—including monocytes, smooth-muscle cells, endothelial cells, and fibroblasts—as a disulfide-linked homodimer. The molecular mass of M-CSF varies because of the synthesis of two distinct M-CSF precursor proteins and the post-transcriptional addition of glycosyl residues and chondroitin sulfate to the molecule. It is one of the few cytokine/growth factors found in measurable concentrations in various tissues including plasma, urine, cerebrospinal fluid, and placenta. Human M-CSF is encoded by a single 20 kb gene containing 10 exons. Its two precursor proteins share amino acid (aa) residues: -32 to +149. M-CSF gene expression is constitutive or inducible in various cell types including fibroblasts, smooth-muscle cells, vascular endothelial cells, bone marrow stromal cells, T cells, uterine cells, hepatocytes, and cells of the monocyte/macrophage lineage. M-CSF is also expressed in malignant cell lines, and gene expression can be induced by endotoxin, IL-1α tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), granulocyte-macrophage colony-stimulating factor (GM-CSF), phorbol esters, and progesterone/estrogen. M-CSF is also found in detectable concentrations in blood, urine, cerebrospinal fluid, and fetal amniotic fluid.

SummaryThe pharmacokinetics of intravenously administered recombinant human factor IX (rhFIX) were studied in Sprague-Dawley rats and Beagle dogs. Rats received rhFIX (50 IU/kg once daily) for 28 days, and the plasma half-life was 5 h. Anti-Human Factor IX serum antibody levels were found in only 1 of 12 rats. The pharmacokinetic profiles of rhFIX or Mononine™, a purified human plasma-derived factor IX, after single 100 IU/kg IV doses in dogs, were similar. Peak plasma concentrations of rhFIX and Mononine™ were 4–5 μg/ml. The mean plasma half-lives were 13.2 ± 1.6 h for rhFIX and 13.3 ± 1.6 h for Mononine™. Dogs also received rhFIX (40 IU/kg IV, daily) for 28 days or Mononine™ (40 IU/kg IV daily) for 14 days. Anti-human Factor IX serum antibody levels were determined for each compound. Pharmacokinetic half-lives decreased in these treated dogs which developed antihuman Factor IX antibodies. The antibody responses in 28 day rhFIX (40 IU/kg) dogs were similar to 14 day Mononine™ (40 IU/kg) dogs.

Currently there is no large animal model of dilated cardiomyopathy. The smaller animal models of cardiomyopathy, such as the Syrian hamster, cannot be studied with echocartography and cardiac catheterization, and the relevance of these models to human dilated cardiomyopathy is open to question. On the basis of some initial observations in Doberman pinschers, it was speculated that these dogs could have occult left ventricular dysfunction. Accordingly, studies were performed in 46 apparently healthy Doberman pinschers and in 41 mongrel dogs: two-dimensional echocardiography (30 dogs in each group), cardiac catheterization (16 Doberman pinschers and 12 mongrels) and coronary blood flow studies (13 Doberman pinschers and 6 mongrels). In the awake, unsedated dogs studied with echocardiography, left ventricular wall thickening was significantly less in the Dobermans than in the mongrels (28% versus 36%, p = 0.0003). In the anesthetized dogs undergoing cardiac catheterization, left ventricular ejection fraction was significantly lower in the Dobermans than in the mongrels (0.38 versus 0.63, p = 0.0001). Rest coronary blood flow and coronary blood flow reserve were similar in the two groups. It is concluded that apparently healthy Doberman pinschers have occult left ventricular dysfunction. These dogs may serve as a large animal model of dilated cardiomyopathy and should not be used experimentally to study normal cardiac physiology.

The HLA-B27 rat is a well-characterized model of human bowel disease, rheumatoid arthritis and psoriasis. Previous studies of chronic inflammation in other rat models of inflammatory disease have demonstrated activation of the kallilrein-kinin system (KKS) as well as modulation by a kallikrein inhibitor and HK deficiency. The effects of C11C1, a monoclonal antibody acting to inhibit cellular binding of high molecular weight kininogen (HK), were studied in the HLA-B27 transgenic rat. Thrice weekly intraperitoneal injections of C11C1 (1.9 mg/kg) or IgG1 (6mg/kg) were given to male HLA-B27 transgenic rats for 3 weeks, beginning when the rats were 23 weeks old. Stool character was scored daily as a measure of intestinal inflammation, and the rear limbs were scored daily for clinical signs of arthritis, tarsal joint swelling and erythema. At the end of the experiment the animals were euthanized, and the colon and tarsal joint histologic lesions were examined. The histology sections were assigned a numerical score for colonic inflammation, synovitis, and cartilage damage. Activation of KKS was assessed by assays of plasma prekallikrein, HK, factor XI, and factor XII. Administration of the monoclonal antibody directed against HK rapidly decreased the clinical scores of inflammatory bowel disease from 3.0 ± 0 to 1.2 ± 0.2 (p

SummaryArterial blood pressure, serum fibrir/fibrinogen degratory products, plasma thromboxane B2, in vitro platelet aggregation, and platelet ultrastructure were studied in ten gravid ewes during fast-triggered ovine pregnancy-induced hypertension and subsequent administration of the thromboxane synthetase inhibitors CGS13080 and CGS12970. During the hypertensive period, blood pressure (p Thromboxane synthetase inhibitor administration lowered blood pressure (p

Selected hemodynamic, renal, and biochemical parameters were assessed in chronically instrumented third-trimester pregnant ewes and in the same ewes after induction of pregnancy toxemia. Ewes with induced pregnancy toxemia developed hypertension, proteinuria, ketonuria, decreased glomerular filtration rate, decreased cardiac output, and decreased left uterine artery blood flow. Histological and transmission electron microscopy revealed the development of renal morphologic changes consistent with those observed in human pregnancy-induced hypertension. These studies have elucidated that pregnancy-induced hypertension can be produced experimentally in the pregnant ewe. Furthermore, the pathophysiologic features of ovine pregnancy toxemia are similar to those of human preeclampsia, and therefore the sheep provides a suitable animal model to study the human condition, which still remains a major complication of pregnancy, jeopardizing both mother and fetus.

SummaryThe effect of aspirin on platelet adhesion to chronically damaged pulmonary arteries was studied in 18 dogs. Chronic injury was produced in all dogs by infection with the canine heartwonn Dirofilaria immitis(DI). Ten dogs were subjected to 4 days of chronic injury. Eight dogs were subjected to 30 days of chronic injury. Five of the 4 day injury and 4 of the 30 day injury dogs received aspirin daily (325 mg/day orally). Aspirin was started 3 days prior to infection with DI. Pulmonary arteries were perfusion fixed in situ at physiologic pressure. The damaged pulmonary arteries were located by Evan’s blue staining (2ml/kg of 1% dye glven one hr prior to perfusion) and prepared for scanning electron microscopy. Both groups of dogs with 4 day DI infection had monolayers of platelets adhered to exposed subendothelium. Aspirin treated dogs had enhanced platelet adhesion to damaged arteries. Aspirin treatment for 33 days reduced platelet adhesion. The damaged arteries of treated dogs infected with DI for 30 days had very few platelets adhering to the damaged surface. However, non-treated dogs subjected to 30 days of infection had platelet adhesion equivalent to the 4 day non-treated infection group. These results suggest that although aspirin is ineffective in preventing platelet adhesion in short term therapy it is effective when given for longer time periods. This inhibitory effect may occur due to platelet membrane changes rather than because of aspirin inhibition of cyclooxygenase.

Erythrocyte morphologic characteristics and serum chemistry results were studied in 10 gravid ewes during experimental ovine pregnancy-induced hypertension and subsequent administration of the thromboxane synthetase inhibitors CGS13080 and CGS12970. During the hypertensive period mean arterial blood pressure, plasma thromboxane B2 levels, and serum chemistry results, and electrolyte levels were significantly altered. Parameters returned to baseline values or were improved after drug administration. Erythrocyte morphologic features did not change significantly with the onset of the syndrome. Echinocytosis was present during baseline measurement and persisted throughout hypertension. However, after thromboxane synthetase inhibition, percentages of discocytes increased (p less than or equal to 0.005) with the same frequency that echinocyte numbers decreased (p less than or equal to 0.05). Schistocytes were present throughout the study, and changes in their numbers were not detected. Serum phosphorus, blood urea nitrogen, and bilirubin levels and anion gap rose significantly during hypertension and returned to normal levels after drug treatment. We speculate that CGS13080 or CGS12970, by decreasing thromboxane levels and blood pressure, promoted the normalization of erythrocyte membranes.

Simultaneous maternal indirect blood pressure measurements, electronic fetal heart rate monitoring, and ultrasonographic biophysical profile testing were used to assess maternal-fetal homeostasis in gravid ewes during gestational days 127 to 134 (term 146), during a 72-hour fast, and during treatment with thromboxane synthetase inhibitors CGS13080 and CGS12970. Seventy-five percent of the ewes (12 of 16) developed clinical signs of ovine pregnancy-induced hypertension, including maternal hypertension and fetal depression. In three untreated hypertensive ewes, pregnancy was terminated by spontaneous premature delivery, and one maternal death occurred after an eclamptic seizure. All nine ewes treated with one of the two thromboxane synthetase inhibitors responded to therapy with decreases in blood pressure and resolution of fetal depression. These nine ewes completed gestation, and were delivered at term. These data indicate that therapy with thromboxane synthetase inhibitors in this animal model of preeclampsia results in profoundly beneficial effects and suggest that further studies of thromboxane synthetase inhibitors are warranted in preeclampsia. (Ann J OBSTET GVNECOL 1989;161:1305-13.)

Scanning electron microscopy (SEM) was used to study pulmonary artery injury 4 days (10 dogs) and 30 days (8 dogs) after transplantation of 6-8 adult canine heartworms (HW) into the pulmonary arteries. Worms were introduced into the jugular vein and allowed to float into position in the main pulmonary artery, where HW are found in naturally occurring infections. One half the dogs in each group were given 323 mg aspirin (ASA)/day starting 3 days before infection. At the end of the 4 or 30 day period all dogs were given 1% Evan’s blue dye (2 ml/kg i.v.), heparin (3,000 units i.v.) and anesthetized. The lungs were perfused at 15 mmHg pressure with Tyrode’s solution followed by 1% glutaraldehyde. Evan’s blue stained areas of pulmonary arteries were dissected and processed for SEM. Dogs were compared for the percentage of surface with endothelial damage, white blood cell and platelet adhesion, and myointimal proliferation. All numerical values show treated dogs vs non-treated dogs (mean ± SE). After 4 days of HW infection the blood vessels of both ASA treated and non-treated dogs exhibited extensive endothelial damage (51 ± 8% vs 81 ± 6%), white blood cell adhesion (56 ± 15% vs 60 ± 12%) and platelet adhesion (36 ± 6% vs 51 ± 9%). Neither group exhibited formation of myointimal proliferation. After 30 days of HW infection blood vessels from ASA treated dogs had less endothelial cell damage (15 ± 6% vs 33 ± 14%), less white blood cell adhesion (13 ± 2% vs 45 ± 9%) and less platelet adhesion (0% vs 25 ± 9%) than non-treated dogs. Myointimal proliferation was observed in both groups (50 ± 16% vs 61 ± 14%), however, the lesions were smaller and less complex in ASA treated dogs. These results suggest that after 4 days of HW infection ASA was ineffective in preventing vascular damage and platelet-leukocyte adhesion. However, continuous ASA therapy during the chronic vascular injury produced by a 30 day HW infection reduced platelet-leukocyte adhesion and the severity of myointimal proliferation. These findings support the suggestion that aspirin protects against formation of atherosclerotic lesions.

Pulmonary hypertension associated with myointimal proliferation is produced by low grade, sustained damage to the arterial surfaces by Dirofilaria immitis (DI) infection in dogs. This study correlated changes during and after infection in pulmonary vascular hemodynamics, arteriograms, and morphology {scanning electron microscopy (SEM) and light microscopy (LM)}. Seven beagles were infected with 50 infective DI larvae. Twelve months after infection, mild pulmonary hypertension {mean pulmonary arterial pressure (MPAP) during normoxia was 26.4 mmHg versus 16.0 pre-infection, during isoproterenol infusion was 37.6 vs. 14.3 pre-infection and reduction of pulmonary vascular resistance was 31.1% versus 47.2% pre-infection} was present. Angiograms at this time revealed dilation and tortuosities of the main and intralobar pulmonary arteries. SEM revealed large villus proliferations, disoriented cell axis, and pore formation. The villi projected (LM) into the vessel lumen and consisted of intimai thickening with multiplying smooth muscle cells and collagen.Seven months after treatment to eliminate the DI as a cause of the arterial trauma, pulmonary hypertension was resolved (MPAP of 19.8 during normoxia, 17.7 during isoproterenol infusion, and reduction of pulmonary vascular resistance of 45.2%). The arteriographie changes of dilation, aneurysms, and tortuosities were decreased, especially in the main and lobar arteries. LM revealed that larger arteries, which had greater arteriographie resolution, had relatively more elastic tissue and that the intralobar arteries had more collagen. SEM revealed that the villus proliferations were markedly reduced in numbers and sizes. This study characterized a reduction of hypertension as related to resolution of the muscular hypertrophy of arteries and related arteriographie changes to the type of connective tissue being produced by smooth muscle cells in the arterial wal.