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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In recent years the treatment of bacterial meningitis has been modified on the basis of a better understanding of its physiopathological mechanisms. It has been shown, for example, that the inflammatory reaction is the primary cause of brain damage in bacterial meningitis. Inflammation and consequent brain damage are greatest in the first hours of antibiotic treatment when rapid and massive bacteriolysis takes place. In effect, the bacterial components activate metabolic pathways and cellular elements leading to the release of inflammation mediators: cytokines (TNF, IL-I) neutrophil degranulation products, complement components and clotting factors. Initially these substances make the blood-fluid and blood-brain barriers permeable. The result is cerebral oedema, excessive fluid pressure, congestion of the cerebral blood vessels and finally endocranial hypertension, reduced cerebral flow, cerebral hypoxia and brain damage. This sequence of events can be stopped by a multifactorial therapy that is not only aetiological (antibiotic) but also treats the inflammation, oedema (Dexamethasone, Mannitol) and symptoms. In this study 129 patients with non-tubercular bacterial meningitis were treated as described. All patients were administered Ceftriaxone (100 mg/kg per diem) Dexamethasone (0.2-0.3 mg/kg/per diem), Mannitol, fluid restriction and--where necessary--intensive symptomatic therapy (against shock, convulsions, fever). Both the antibiotic and the corticosteroid were also administered intrathecally at the time of the first lumbar puncture at intake. Of these 129 patients, 7 died very soon after admission as they had arrived in a moribund condition. Duration of therapy was 3-6 days in 90% of these cases. There were no recurrences.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Rational basis of modern therapy of bacterial meningitis. Review of the literature and our clinical experience of 122 pediatric cases. 180 76

Rats produced more TNF activity in cerebrospinal fluid (CSF) than in blood after intracerebroventricular (i.c.v.) injection of lipopolysaccharide (LPS). After intravenous (i.v.) LPS, blood TNF levels exceeded CSF levels. Thus, brain cells appear to produce TNF in response to LPS. Rats with the stroke-risk factors hypertension or combined hypertension and genetic stroke-proneness produce more TNF in response to a provocative dose of LPS i.v. than control animals free of these risk factors. The possible relevance to stroke vulnerability is discussed.
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PMID:Lipopolysaccharide-induced production of tumor necrosis factor activity in rats with and without risk factors for stroke. 202 11

A phase I trial of human recombinant tumor necrosis factor (rH-TNF) has been carried out in patients with advanced solid tumors. Sixty-six courses of the drug were given by 1 h IV infusion, daily for 5 days to 33 patients at doses of 5, 10, 20, 30, 45, 60, and 80 x 10(4) U/m2/day. All patients received isotonic saline (up to 21/day) and either indomethacin or ketoprofen. Acute toxicity resembled that seen with the phase I study of a single dose (5). Dose limiting toxicity was acute, rapidly reversible, hepatic dysfunction and hypotension. Hypertension during drug infusion and dyspnea were marked in some patients. There was one complete and one minor response, both in patients with renal cell carcinoma. The dose of 80 x 10(4) U/m2/day x 5 was poorly tolerated and the recommended starting dose for phase II studies is 60 x 10(4) U/m2/day x 5. Caution is recommended in treating patients with pre-existing hepatic function abnormalities, hypertension, hypotension or significant obstructive airway disease.
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PMID:A phase I clinical trial of recombinant human tumor necrosis factor given daily for five days. 292 76

A phase I and pharmacokinetic study of recombinant tumor necrosis factor (rH-TNF Asahi) was carried out in 29 patients, who received a total of 72 courses with doses ranging from 1 to 48 X 10(4) units/m2. Drug was given as 1-h i.v. infusions. Acute toxicities, taking the form of fever, chills, tachycardia, hypertension, peripheral cyanosis, nausea and vomiting, headache, chest tightness, low back pain, diarrhea and shortness of breath were seen, but were not dose-limiting or dose-related. Some early rise in SGOT, without any change in serum bilirubin, was noted at the highest doses. Eosinophilia, monocytosis, mild hypocalcemia and an increase in fibrin degradation products were seen in a few patients. The dose-limiting toxicity was hypotension, which occurred after the end of the drug infusion and was seen in all 5 patients treated at the highest dose. There was no mortality or long-term morbidity. There were no responses. Pharmacokinetic studies indicated a rapid plasma clearance and a short plasma half-life, generally less than 0.5 h.
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PMID:Phase I clinical trial of recombinant human tumor necrosis factor. 366 33

In the final two years, June 1991 to June 1993, of the Letterman Army Institute of Research, a variety of cell, tissue, organ, and animal systems were used to explore the toxicities of model hemoglobin (Hb) solutions produced in the sterile Hb production facility. Human mononuclear cells release TNF alpha and Il-8 when exposed to chromatographically purified human Hb (HbA0). Mixed cultures of fetal mouse neurons and glial cells exhibit neuronal death with exposure to HbA0 in a dose and time dependent manner while the glial cells are not injured. Isolated perfused rabbit hearts were used to explore the reversibility of coronary vasoconstriction after Hb and cyanomet-Hb administration, and deferoxamine was shown to partially protect that reversibility. In rabbits HbA0 and human Hb cross-linked with bis(3,5-dibromosalicyl) fumarate (alpha alpha Hb) caused hypertension and pulmonary arteritis. In swine, HbA0 and alpha alpha Hb caused systemic and pulmonary hypertension and a doubling of the vascular resistance that was equivalent to that seen with inhibition of nitric oxide synthesis. Elevations of creatine kinase and lactic dehydrogenase activity were observed after Hbs were infused, but not after blockade of nitric oxide synthesis. Acute renal failure seen after administration HbA0, did not appear after alpha alpha Hb. Infusion of cyanomet-alpha alpha Hb did not cause the increased vascular resistance seen after alpha alpha Hb. The infusion of 1-arginine or nitroglycerine with alpha alpha Hb did not prevent the increased vascular resistance and decreased cardiac output or allow the increased oxygen carrying capacity provided by Hb in the plasma from translating into improved oxygen delivery or improved oxygen consumption.
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PMID:Review of modified hemoglobin research at Letterman: attempts to delineate the toxicity of cell-free tetrameric hemoglobin. 749 49

Pregnancy is associated with modifications in the maternal immune system that may be involved in the absence of rejection of the fetoplacental graft characterized by the presence of paternal antigens. This active and specific tolerance towards the fetoplacental unit seems to be compromised in pregnancy-induced hypertension (PIH). To evaluate whether the immunological state in patients with PIH is altered with respect to normal pregnant women we studied 15 patients with PIH, 15 uncomplicated pregnant and 10 healthy nonpregnant women using monoclonal antibodies directed to specific lymphocyte antigen determinants, cytokines (TNF) and soluble molecules (sIL-2R, sCD8). The percentage of CD4 lymphocytes and of natural killer (NK) cells was significantly higher in PIH patients compared to controls (CD4: 42.9 +/- 10.5 vs. 32.7 +/- 12.5%; p < 0.05; NK: 14.7 +/- 6.3 vs. 8.3 +/- 3.4%; p < 0.01). However, these values did not differ when compared to normotensive nonpregnant controls (CD4: 53.1 +/- 5.9%; NK: 17.2 +/- 7.1%). In addition, the soluble IL-2 receptor (sIL-2R) was higher in PIH patients when compared to control patients (725.5 +/- 194.2 vs. 482.5 +/- 187.2 U/ml; p < 0.01). The immune response observed in normal pregnancies responsible for the tolerance towards the fetoplacental unit seems to be altered in PIH patients as suggested by higher levels of CD4 and NK cells, and sIL-2R. This may lead to a chronic rejection syndrome and be involved in the pathophysiology of PIH.
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PMID:Cell-mediated immunity imbalance in pregnancy-induced hypertension. 785 7

Lipopolysaccharide (LPS)-induced (i.v. or i.c.v., 1.8 mg/kg) release of von Willebrand factor (vWF) was examined in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. SHR rats released significantly (P < 0.05) more vWF than WKY rats in response to LPS. LPS also inhibited factor VIII procoagulant activity (FVIII:c) which may indicate an increase in thrombin activity. Cultured cerebrovascular endothelial cells (EC) derived from both SHR and WKY rats, as well as human umbilical vein EC (HUVEC) cultures constitutively released vWF. Treatment with agonists including LPS, thrombin and tumor necrosis factor-alpha (TNF alpha) did not affect the in vitro secretion of vWF by cerebrovascular EC cultures but significantly upregulated vWF release by HUVEC cultures. Preincubation of cerebrovascular EC cultures with interleukin-1 (IL-1) +/- TNF alpha or co-culturing in the presence of LPS-activated syngeneic monocytes had no effect on vWF secretion. The findings demonstrate that conditions of hypertension may affect endothelial cells and make them more responsive to agonist stimulation and thereby increase secretion of vWF, an important factor in hemostasis as well as thrombosis. The capacity of LPS to significantly affect the in vivo secretion of vWF in SHR and WKY rats but not cultured cerebrovascular EC indicates that observed elevations in plasma vWF were not derived from cerebrovascular EC. It is suggested that hypertension may function as a risk factor for thrombotic stroke by influencing factors involved in coagulation processes, such as vWF and factor VIII:c.
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PMID:Agonist-stimulated release of von Willebrand factor and procoagulant factor VIII in rats with and without risk factors for stroke. 792 3

Accumulating evidence tends to demonstrate that inflammatory processes are responsible for neurological damage and sequelae in bacterial meningitis in children and infants. Massive liberation of bacterial cell wall components (Lipopolysaccharide, acid teichoic polymers) induce a cascade of reactions including the secretion of many cytokines (such as TNF alpha and IL-1 beta) and prostaglandins (such as PAF and PGE2) which in turn leads to the development of cerebral oedema, intracranial hypertension and cerebral blood flow reduction. Dexamethasone (DXM) is effective at the beginning of the inflammatory cascade and its utilisation in the meningitis experimental model in animals has shown significant reduction in the inflammatory response to bacterial meningitis. The first clinical studies using DXM as an adjunctive therapy to antibiotics have demonstrated its beneficial effect in terms of complications and long-term neurological sequelae in Haemophilus influenzae meningitis in children and infants. It seems that a similar effect can be obtained in meningococcal and pneumococcal meningitis. Little information is actually available concerning the use of DXM in penicillin-resistant pneumococcal meningitis. The rare reported cases of ceftriaxone failure with DXM as treatment of penicillin-resistant pneumococcal meningitis had a favorable outcome with the use of vancomycin.
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PMID:[Role of dexamethasone in the treatment of purulent meningitis in infants and in children]. 839 88

It has been hypothesized that inadequate placentation in the hypertensive disorder of pregnancy known as preeclampsia creates foci of placental ischemia/hypoxia leading to the elaboration of factors that compromise systemic endothelial function to produce disease sequelae. As tumor necrosis factor-alpha (TNF alpha) and interleukin-1 (IL-1) are inflammatory cytokines capable of eliciting endothelial cell dysfunction, we investigated whether the production of these inflammatory cytokines by cultured villous explants from the human placenta was affected by incubation in reduced oxygen (2% O2). The term placenta produced TNF alpha, IL-6, and low levels of IL-1alpha and IL-1beta under standard tissue culture conditions. Hypoxia significantly increased TNF alpha, IL-1alpha, and IL-1beta production by 2-, 6-, and 23-fold, respectively, but did not affect IL-6 production. Further, cytokines were immunolocalized to the syncytiotrophoblast layer as well as to some villous core cells. Hypoxic regulation of placental TNF alpha and IL-1beta production also appeared to differ based on gestational age. Finally, treatment with either cobalt chloride or an iron chelator mimicked the hypoxic response, suggesting that stimulation of placental cytokine production may involve a heme-containing, O2-sensing protein. These results suggest that placental hypoxia can lead to the elaboration of inflammatory cytokines, which may contribute to the pathophysiology of preeclampsia.
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PMID:Hypoxia stimulates cytokine production by villous explants from the human placenta. 914 53

We tested the concept that tumor necrosis factor-alpha (TNF-alpha) or platelet-activating factor (PAF) mediated Escherichia coli endotoxin lipopolysaccharide (LPS)-induced upregulation of nitric oxide (NO) and acute-phase hypotension (APH) in the rat. LPS (0.5 mg/kg i.v.) given to rats treated with saline or nonimmune goat-derived gamma-globulin (immunoglobulin G, 22 mg/kg i.m.) produced APH and increased plasma concentrations of TNF-alpha and nitrate and nitrite anions (reactive nitrogen intermediates; RNI) and NO in ex vivo incubates of polymorphonuclear neutrophils (PMN) and inducible NO synthase (iNOS) mRNA in PMN. Pretreatment of rats with a polyclonal TNF-alpha antibody (TNF-Ab, 22 mg/kg i.m.) abolished LPS-mediated increases in plasma TNF-alpha but failed to inhibit APH or the NO system. TNF-alpha (8.2 micrograms/kg i.v.) produced transient hypertension and sustained tachycardia and increased plasma TNF-alpha and PMN iNOS mRNA but not RNI. LPS and TNF-alpha decreased spontaneous and calcimycin (Ca2+ ionophore, 1 microM)- and PAF (1 microM)-mediated increases in head-space NO production by rings of mesenteric artery incubated ex vivo. TNF-Ab abolished all effects of TNF-alpha. PAF (25, 50, and 100 ng/kg) produced APH without increasing plasma TNF-alpha, RNI, or PMN iNOS mRNA. The PAF receptor antagonist BN-50730 (80 micrograms/kg i.v.) abolished PAF-induced APH and attenuated LPS-induced increases in RNI. We conclude that 1) LPS produces parallel but unrelated changes in TNF-alpha and RNI in plasma and PMN during the APH of endotoxemia; and 2) endogenous TNF-alpha is not required for LPS-mediated induction of iNOS mRNA, and PAF mediates LPS-induced APH.
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PMID:Dissociation of TNF-alpha from endotoxin-induced nitric oxide and acute-phase hypotension. 924 87


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