Activation of blood platelets after percutaneous transluminal coronary angioplasty and coronary artery bypass graft surgery

We have evaluated the activation of platelets in blood samples taken from patients with stable angina undergoing balloon angioplasty (percutaneous transluminal coronary angioplasty [PTCA]) (n=11) or coronary artery bypass grafting (CABG) under hypothermic (n=11) or normothermic conditions (n=11). We have found that surface expression of P-selectin on platelets in whole blood from PTCA patients upon thrombin treatment was significantly reduced, as compared with control platelets from healthy subjects. This effect was partially reversed when platelets washed from the same blood sample were used, but even then P-selectin expression was significantly lower in PTCA patients than it was in control subjects. There was a significant increase in basal expression of P-selectin in blood platelets taken from patients who underwent CABG under normothermic conditions (warm blood cardioplegia) as opposed to hypothermic patients (cold crystalloid cardioplegia). These platelets retain the ability to respond to agonists, although to a much lower extent than do those from healthy control donors. The surface exposure of P-selectin on resting and thrombin-treated platelets isolated from CABG surgery patients was not different from that of the control platelets. The adhesion to fibrinogen of resting and thrombin-treated platelets from patients who underwent balloon angioplasty as well as CABG surgery under normothermic and hypothermic conditions was significantly reduced when compared with the fibrinogen of the control platelets. These results suggest that the function of platelet fibrinogen receptor is impaired in patients with stable angina pectoris and that PTCA and CABG surgery activates platelets.

Complete inhibition of rhabdomyosarcoma xenograft growth and neovascularization requires blockade of both tumor and host vascular endothelial growth factor

Growth of the human rhabdomyosarcoma A673 cell line in nude mice is substantially reduced but not completely suppressed after systemic administration of the antihuman vascular endothelial growth factor (VEGF) monoclonal antibody (Mab) A.4.6.1. Potentially, such escape might be attributable to incomplete local penetration of the antibody because of a diffusion barrier associated with tumor growth. Alternatively, it might reflect a compensatory up-regulation of murine VEGF, produced by the stroma of the host, or of other angiogenic factor genes. To test these potential mechanisms, systemic administration of Mab A.4.6.1, was performed in conjunction with intratumoral administration of an irrelevant antibody, an antihuman VEGF Fab or mFlt(1-3)-IgG that neutralizes both human and murine VEGF. Tumor growth in the systemic-plus-intratumoral anti-VEGF group was not different from that in the systemic anti-VEGF-plus-intratumoral-control antibody group, arguing against the possibility that bioavailability is the factor that limits the antitumor efficacy of Mab A.4.6.1. However, intratumoral mFlt(l-3)-IgG administration dramatically enhanced the activity of systemic anti-VEGF Mab and resulted in complete suppression of tumor growth, which indicated that host VEGF significantly contributes to tumor growth. Systemic administration of mFlt(1-3)-IgG alone replicated these findings. Histological analysis of residual tumor tissues revealed an almost complete absence of host-derived vasculature and massive tumor-cell necrosis in the mFlt(1-3)-IgG groups. Such extensive necrotic areas were not present in the other groups. Real-time reverse transcription-PCR analysis of total RNA derived from tumor tissues indicated strong up-regulation of both human and murine VEGF as well as other genes regulated by hypoxia. Our findings emphasize the need to completely block VEGF for maximal inhibition of tumor growth.

Stressful life events, bipolar disorder, and the "kindling model"

A common misconception is that bipolar disorder is an endogenous process. However, previous research suggests a role for life events in the onset of and recovery from bipolar episodes. Yet, there remains some question as to whether the relationship between life events and onset changes over the course of the disorder as a result of the number of episodes an individual has experienced. Using a rigorous interview measure of stressful life events, the current study tested the kindling model (R. M. Post, 1992), which theorizes that major life events play a diminishing role over the course of illness in bipolar patients. Analyses revealed that the number of episodes experienced does not appear to have a significant effect on bipolar 1 patients' reactivity to external stressors. In addition, the results suggest that a more complex relationship exists among age, stress, and onset of new episodes than can be adequately explained by the kindling model.

In-vitro immunomodulatory effects of haloperidol and perazine in schizophrenia

There are some reports describing concurrent changes in lymphocytic and monocytic activities in schizophrenia. In this study we investigated T cell activity in schizophrenic patients by measuring the release of interleukin-2 (IL-2) and soluble interleukin-2 receptor (sIL-2R) by T cells and the percentages of CD4+ and CD8+ cells in blood. The release of IL-2 and sIL-2R by T cells was evaluated in dilute whole blood after in-vitro stimulation with phytohemagglutinin. IL-2 levels and the percentage of CD4-cells tended to decrease and sIL-2R levels decreased significantly in schizophrenic patients. Haloperidol and perazine significantly decreased IL-2 levels and increased sIL-2R levels and the percentage CD4-cells. IL-2 and sIL-2R levels were lower in patients with a predominance of positive symptoms. The neuroleptic-induced increase in sIL-2R levels was higher in patients with a predominance of positive symptoms compared with those in whom both positive and negative symptoms were severe. The study has shown that T-cell activity is reduced in schizophrenia and that neuroleptics may have immunomodulatory properties.

Elevated levels of lipoprotein(a) in familial bone marrow edema syndrome of the hip

There is controversy whether bone marrow edema syndrome represents a distinct transient disease or reflects an early reversible phase of spontaneous osteonecrosis of the hip. Hypofibrinolysis on the basis of elevated plasma levels of plasminogen activator inhibitor or lipoprotein(a) or both has been reported to favor the development of bone marrow edema syndrome and nontraumatic avascular necrosis. The current authors report on the familial occurrence of transient bone marrow edema syndrome of the hip in three female family members. Plasma concentrations of lipoprotein(a) were elevated in all three patients, whereas serum levels of plasminogen activator inhibitor were within normal ranges. This first familial description of transient bone marrow edema syndrome of the hip strongly suggests that a genetically determined elevation of lipoprotein(a) may be an important predisposing factor in these patients.

A repressor sequence in the juxtamembrane domain of Flt-1 (VEGFR-1) constitutively inhibits vascular endothelial growth factor-dependent phosphatidylinositol 3'-kinase activation and endothelial cell migration

Vascular endothelial growth factor (VEGF) has two highly homologous tyrosine kinase receptors: Flt-1 (VEGFR-1) and KDR (VEGFR-2). KDR is strongly phosphorylated on tyrosines and can transmit mitogenic and motogenic signals following VEGF binding, while Flt-1 is markedly less effective in mediating such functions. To dissect the regions that account for the differences between the two receptors, we generated a series of chimeric Flt-1-KDR molecules. We found that the juxtamembrane region of Flt-1 prevents key signaling functions. When the juxtamembrane region of Flt-1 is replaced by that of KDR, Flt-1 becomes competent to mediate endothelial cell migration and phosphatidylinositol 3'-kinase activation in response to VEGF. Further mutational analysis shows that a short divergent sequence is responsible for such repressor function. However, mutant Flt-1 receptors lacking this sequence do not transmit effective proliferative signals, suggesting that this receptor function is regulated separately. These results define a novel functional domain that serves to repress Flt-1 activity in endothelial cells.

[Effect of trimetazidine on biological activity of neutrophils in patients with transient myocardial ischemia induced by exercise testing]

We estimated the effect of trimetazidine on biological activity of neutrophils in patients with exercise test--induced transient myocardial ischaemia. The study group comprised 16 patients (10 men and 6 women) aged 40-56 years (mean 48.2 years) with stable angina. Exercise test was performed on cycloer-gometer (Medicor, Hungary). Trimetazidine in a dose 3 x 20 mg/day was applied 24 hours prior to the exercise test. The control group consisted of 14 patients (9 men and 5 women) aged 37-59 years (mean 47.9 years), with stable angina, in whom exercise test was performed but the drug was not administered. Blood samples for examination were taken from basilic vein before the exercise test and 10 min afterwards. To evaluate the ability of neutrophils to aggregate the leukergy test of Fleck modified by Berliner and Aronson was applied. Oxidative metabolism of nonstimulated and stimulated by fMLP and PMA was measured using chemiluminescence method. It was shown that in patients with stable angina trimetazidine caused decrease in neutrophil aggregation. The drug did not inhibit neutrophil biological activity af-ter exercise test--induced myocardial ischaemia.

Augmenting effect of methionine-enkephalin on interleukin-6 production by cytokine-stimulated murine macrophages

The effects of methionine-enkephalin on the production of interleukin-6 by activated peritoneal murine macrophages were studied. Macrophage were activated with interleukin-1beta or interferon-gamma in the presence or absence of graded concentrations of methionine-enkephalin. Methionine-enkephalin combined with interleukin-1beta or interferon-gamma caused an increase in IL-6 release from cultured macrophages. The opioid receptor antagonist naloxone did not change the stimulatory effect of methionine-enkephalin on IL-6 production by stimulated macrophages. Methionine-enkephalin added to the culture medium of resting macrophages increased IL-6 release from macrophages which were later induced with interleukin-1beta or interferon-gamma. The results of this study suggest that methionine-enkephalin can modulate the proinflammatory cytokine response by controlling, via non-opioid receptor mechanism, the production of IL-6.

Pain management: an organizational commitment

Although much has been done to promote pain assessment and management, pain remains a major, yet largely preventable, public health problem in the United States. A strategy that has been proposed to assure optimal pain management is the development of formal means within institutions to evaluate pain management practices and foster improved outcomes. In response to a pain-related patient care problem, South Nassau Communities Hospital recognized the need to undertake more formal methods for managing patients with acute, chronic, and cancer pain. A Pain Management Task Force was charged with the development of a comprehensive pain management program. Its efforts to date and plans for the future position this institution as ready for the Joint Commission for the Accreditation of Healthcare Organizations' pain assessment and management standards that were introduced in 2000.

Respiratory responses to chemical stimulation in patients with obstructive sleep apnoea

Chemical control of breathing in obstructive sleep apnoea (OSA) patients has been studied by many authors. The results of previous studies, especially those dealing with hypoxic drive, are discordant. Respiratory responses were studied during hypercapnic and hypoxic stimulation in a group of 37 normocapnic patients with OSA during wakefulness. The diagnosis of OSA was established by standard polysomnography. These patients had increased apnoea/hypopnoea index (AHI; 51 +/- 22 (mean +/- SD)), obesity (body mass index (BMI) 32.4 +/- 5.6 kg.m-2) and normal lung function tests. The control group consisted of 14 healthy obese subjects (BMI 31.2 +/- 3.3 kg.m-2). Respiratory responses (ventilatory and mouth occlusion pressure (P0.1)) during hypercapnic and hypoxic rebreathing tests were measured with the use of computerized equipment. Respiratory responses during hypercapnic stimulation were similar to those in the control group (change in (delta) minute ventilation (V'E)/delta carbon dioxide tension (PCO2) 23.5 +/- 14.8 versus 22.3 +/- 10.0 L.min-1.kPa-1, delta P0.1/delta PCO2 4.6 +/- 3.6 versus 4.2 +/- 2.6 cmH2O.kPa-1). During isocapnic hypoxic stimulation in OSA patients the mean ventilatory response was higher than in the control group (delta V'E/delta arterial oxygen saturation (Sa,O2) 2.6 +/- 1.7 versus 1.7 +/- 0.7 L.min-1.%-1) but this difference was not statistically significant. Nevertheless, it was found that 13 (35%) OSA patients had increased ventilatory responses. The mean P0.1 response in OSA patients was higher but did not differ significantly from those in the control group (delta P0.1/delta Sa,O2) 0.43 +/- 0.38 versus 0.35 +/- 0.12 cmH2O.%-1). The results demonstrated that respiratory responses to chemical stimulation in awake normocapnic patients with obstructive sleep apnoea were in the normal range, similar to those in control obese subjects. During hypoxic stimulation some of them had increased ventilatory (35%) and mouth occlusion pressure (16%) responses.

Bayesian analysis of prevalence with covariates using simulation-based techniques: applications to HIV screening

Ignoring the limited precision of medical diagnostic tests can incur serious bias in prevalence estimation. Conversely, treating the values of sensitivity and specificity as constants, as in most studies, inevitably underestimates the variability of prevalence estimates. Bayesian inference provides a natural framework with which to integrate the variability in the estimates of sensitivity and specificity with estimation of prevalence. However, the resulting model becomes quite complicated and presents a computational challenge. Recently, Mendoza-Blanco et al. proposed a missing-data approach with simulation-based techniques to deal with the computational difficulties. Although their approach is quite effective in reducing the computational complexity into manageable tasks, their developed methodology is not general enough for modelling the effects of covariates in prevalence estimation. In this paper, we extend their work in this direction by combining their missing-data approach with a latent variable technique for modelling discrete data. The present work also generalizes the methods of Albert and Chib for Bayesian analysis of binary response data with errors in the response. We illustrate the methodology with several real data examples extracted from the literature.

Slope analysis of Auditory Brainstem Responses in children at risk of central auditory processing disorders

The method of slope vectors was used to quantify Auditory Brainstem Responses (ABR) obtained from nine normal children and nine children at risk for central auditory processing disorders (CAPD) with language impairment, for monaural and binaural stimulation conditions. Slopes thus obtained were subjected to K-Means Cluster Analysis. Distinction between the two groups was obtained only for binaural stimulation conditions, wherein all normal children were grouped under cluster 1 with higher slope values and 6 out of 9 CAPD children were grouped under cluster 2 with lower slopes. The results suggest that there may be several subcategories among children who are found to be at risk for CAPD. One of the subcategories may comprise children who exhibit poor ABR morphology, especially during binaural stimulation conditions, which could be due to binaural interference.

The effects of ordered-series-of-motifs anchoring and sub-class modeling on the generation of HMMs representing highly divergent protein sequences

Hidden Markov Models (HMMs) provide a flexible method for representing protein sequence data. Highly divergent data require a more complex approach to HMM generation than previously demonstrated. We describe a strategy of motif anchoring and sub-class modeling that aids in the construction of more informative HMMs as determined by a new algorithm called a stability measure.

VEGF couples hypertrophic cartilage remodeling, ossification and angiogenesis during endochondral bone formation

Hypertrophic chondrocytes in the epiphyseal growth plate express the angiogenic protein vascular endothelial growth factor (VEGF). To determine the role of VEGF in endochondral bone formation, we inactivated this factor through the systemic administration of a soluble receptor chimeric protein (Flt-(1-3)-IgG) to 24-day-old mice. Blood vessel invasion was almost completely suppressed, concomitant with impaired trabecular bone formation and expansion of hypertrophic chondrocyte zone. Recruitment and/or differentiation of chondroclasts, which express gelatinase B/matrix metalloproteinase-9, and resorption of terminal chondrocytes decreased. Although proliferation, differentiation and maturation of chondrocytes were apparently normal, resorption was inhibited. Cessation of the anti-VEGF treatment was followed by capillary invasion, restoration of bone growth, resorption of the hypertrophic cartilage and normalization of the growth plate architecture. These findings indicate that VEGF-mediated capillary invasion is an essential signal that regulates growth plate morphogenesis and triggers cartilage remodeling. Thus, VEGF is an essential coordinator of chondrocyte death, chondroclast function, extracellular matrix remodeling, angiogenesis and bone formation in the growth plate.

Pentoxifylline decreases neutrophil respiratory bursts in patients with stable angina

We estimated the effect of pentoxifylline (PTX) on the respiratory burst (examined by chemiluminescence method) of unprimed and primed neutrophils with tumor necrosis factor-alpha (TNF-alpha) in patients with stable angina pectoris. Chemiluminescence of non-stimulated as well as formyl-methionyl-leucyl-phenylalanine (fMLP) and phorbol myristate acetate (PMA) stimulated neutrophils was measured. We studied 45 patients with stable angina subjected to percutaneous transluminal coronary angioplasty (PTCA) procedure, who were randomly divided into two groups. The study group consisted of 24 patients who were administered pentoxifylline orally, and the control group consisted of 21 patients without pentoxifylline administration. Blood samples for examination were collected from the coronary sinus and peripheral vein just before the PTCA procedure. Pentoxifylline decreased the respiratory burst of non-stimulated and fMLP-stimulated neutrophils without affecting the chemiluminescence of PMA stimulated neutrophils. Moreover, pentoxifylline diminished the chemiluminescence non-stimulated and stimulated by fMLP but not by PMA of TNF-alpha primed neutrophils. We presume that administration of PTX in stable angina patients may have a beneficial effect.

[The effect of astrocytoma cells on secretion of cytokines by autologous lymphocytes]

Immunotherapy is one of the experimental methods used in the treatment of brain tumours. The development of astrocytomas is accompanied by decreased activity of lymphocytes, namely inhibition of mitogen-induced proliferation and decreased cytokine secretion, which is an adverse event in the course of disease. In the present study, astrocytoma cells obtained from human tumours and cocultured with autologous lymphocytes inhibited cytokine secretion by those lymphocytes.

Peroxisome proliferator-activated receptor gamma ligands are potent inhibitors of angiogenesis in vitro and in vivo

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor that functions as a transcription factor to mediate ligand-dependent transcriptional regulation. Activation of PPARgamma by the naturally occurring ligand, 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2), or members of a new class of oral antidiabetic agents, e.g. BRL49653 and ciglitizone, has been linked to adipocyte differentiation, regulation of glucose homeostasis, inhibition of macrophage and monocyte activation, and inhibition of tumor cell proliferation. Here we report that human umbilical vein endothelial cells (HUVEC) express PPARgamma mRNA and protein. Activation of PPARgamma by the specific ligands 15d-PGJ2, BRL49653, or ciglitizone, dose dependently suppresses HUVEC differentiation into tube-like structures in three-dimensional collagen gels. In contrast, specific PPARalpha and -beta ligands do not affect tube formation although mRNA for these receptors are expressed in HUVEC. PPARgamma ligands also inhibit the proliferative response of HUVEC to exogenous growth factors. Treatment of HUVEC with 15d-PGJ2 also reduced mRNA levels of vascular endothelial cell growth factor receptors 1 (Flt-1) and 2 (Flk/KDR) and urokinase plasminogen activator and increased plasminogen activator inhibitor-1 (PAI-1) mRNA. Finally, administration of 15d-PGJ2 inhibited vascular endothelial cell growth factor-induced angiogenesis in the rat cornea. These observations demonstrate that PPARgamma ligands are potent inhibitors of angiogenesis in vitro and in vivo, and suggest that PPARgamma may be an important molecular target for the development of small-molecule inhibitors of angiogenesis.

VEGF is required for growth and survival in neonatal mice

We employed two independent approaches to inactivate the angiogenic protein VEGF in newborn mice: inducible, Cre-loxP- mediated gene targeting, or administration of mFlt(1–3)-IgG, a soluble VEGF receptor chimeric protein. Partial inhibition of VEGF achieved by inducible gene targeting resulted in increased mortality, stunted body growth and impaired organ development, most notably of the liver. Administration of mFlt(1–3)-IgG, which achieves a higher degree of VEGF inhibition, resulted in nearly complete growth arrest and lethality. Ultrastructural analysis documented alterations in endothelial and other cell types. Histological and biochemical changes consistent with liver and renal failure were observed. Endothelial cells isolated from the liver of mFlt(1–3)-IgG-treated neonates demonstrated an increased apoptotic index, indicating that VEGF is required not only for proliferation but also for survival of endothelial cells. However, such treatment resulted in less significant alterations as the animal matured, and the dependence on VEGF was eventually lost some time after the fourth postnatal week. Administration of mFlt(1–3)-IgG to juvenile mice failed to induce apoptosis in liver endothelial cells. Thus, VEGF is essential for growth and survival in early postnatal life. However, in the fully developed animal, VEGF is likely to be involved primarily in active angiogenesis processes such as corpus luteum development.