Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of experimental meningitis on regional cerebral blood flow (rCBF), cerebral metabolic rate for oxygen (CMRO2), and cerebrovascular responsiveness to CO2 was determined in pentobarbital-anesthetized rabbits. The animals were inoculated intracisternally with saline (control) or log-phase Haemophilus influenzae type b (Hib). Eighteen hours later rCBF was determined with radiolabeled microspheres at normocapnia, hypocapnia, and hypercapnia. Cerebrovascular responses to hypocapnia and hypercapnia were assessed by calculating the change in cerebrovascular resistance per millimeter mercury change in PaCO2. At all CO2 levels, meningitis (M) was associated with elevated CBF compared with control (C: 47.5 +/- 3.0, M: 60.9 +/- 4.5 ml.100 g-1.min-1 at normocapnia, P < 0.01). Regional differences were present. In forebrain, the hyperemia in meningitis was confined to the superficial cortical grey matter. When compared with control, meningitis was not associated with altered vasoreactivity during hypocapnia (C: -0.026 +/- 0.006, M: -0.026 +/- 0.008 mmHg.ml-1 x 100 g-1.min-1.mmHg PaCO2(-1)) or hypercapnia (C: -0.037 +/- 0.004, M: -0.026 +/- 0.008 mmHg.ml-1 x 100 g.min.mmHg PaCO2(-1)). CMRO2 in meningitis was not significantly different from control (C: 3.53 +/- 0.29, M: 3.51 +/- 0.22 ml O2.100 g-1.min-1). These findings indicate that cerebrovascular responsiveness to CO2 is preserved in experimental Hib meningitis. Furthermore, enhanced CBF together with unchanged CMRO2 indicates that "luxury" cerebral perfusion is present in this model of bacterial meningitis.
 ...
PMID:Cerebrovascular responsiveness to CO2 in Haemophilus influenzae type b meningitis in rabbits. 820 76

The effect of leukocytes on regional cerebral blood flow (rCBF) and cerebrovascular autoregulation in experimental meningitis was determined in rabbits. Four groups of animals were studied. Cerebrospinal fluid (CSF) leukocyte migration was prevented in two groups by pretreatment with 1.5 mg/kg of IB4, a monoclonal antibody directed against CD11/18 leukocyte adhesion receptors. Intracisternal inoculation was performed with saline (control and control-IB4 groups) or Haemophilus influenzae type b (Hib and Hib-IB4 groups). Eighteen hours later, rCBF was determined with radiolabeled microspheres. Autoregulation was assessed by graded hemorrhagic hypotension. Compared with untreated meningitis (Hib group), IB4-pretreated meningitis (Hib-IB4 group) was associated with a reduced CSF leukocyte count (1,980 +/- 880 vs. 200 +/- 110 cells/microliter; P < 0.05) and an elevated CSF colony count (2.87 +/- 0.08 vs. 5.63 +/- 0.72 log10colony-forming units/ml; P < 0.05). Compared with control, baseline CBF was elevated in both untreated and IB4-pretreated meningitis (51 +/- 2, 54 +/- 2, 66 +/- 5, and 102 +/- 17 ml.100 g-1.min-1 in control, control-IB4, Hib, and Hib-IB4 groups, respectively). The degree of hyperemia in meningitis was related to the CSF colony count, with a high CBF occurring in animals with high colony counts. During hypotension, CBF remained at or above baseline in the Hib group and both control groups, indicating preservation of cerebrovascular autoregulation in untreated Hib meningitis. In the Hib-IB4 group, the elevated baseline CBF was not maintained during hypotension, falling to 51% of baseline at a cerebral perfusion pressure of 30 mmHg and indicating impairment of cerebrovascular autoregulation. These results suggest that CSF leukocytes are not primarily responsible for the hyperemic response in Hib meningitis. Cerebral hyperemia may be induced either directly by bacterial components or indirectly by components of the inflammatory cascade that precede CSF leukocyte migration.
 ...
PMID:Role of leukocytes in cerebral autoregulation and hyperemia in bacterial meningitis in rabbits. 924 13