摘要:

Obstruction of narrow vessels by rigid neutrophils may contribute to ischemic organ injury. In septicemia, a substantial portion of the neutrophils may become activated and the number of circulating immature neutrophils may rise sharply. Volume and deformability of mature (PMN) and immature neutrophils in healthy preterm and full-term infants and in septicemic neonates were studied by means of a micropipette system. Membrane cytoplasm tongues were aspirated into 2.5-µm (diameter) pipettes over a period of 60 s. Volume and tongue growth of mature resting PMN were similar in healthy preterm and full-term neonates and adults. Compared with mature PMN (about 360 fl), the volumes of band cells (415 fl), metamyelocytes (470 fl), and less mature cells (myeloblasts, promyelocytes, and myelocytes; 490 fl) were significantly increased (p< 0.005). Final tongue lengths of band cells, metamyelocytes, and less mature cells were decreased by about 50, 60, and 70%, respectively, when compared with passive mature cells. In septic neonates, the percentage of immature neutrophils was increased, but the deformability and volume of the cell subpopulations were not affected by septicemia. Active PMN were characterized by pseudopod formation. More active PMN were found in group B streptococcal (14% of total PMN), Gram-negative (12%), andStaphylococcus epidermidissepticemia (8%) than in healthy neonates and adults (4%). The main bodies of active PMN were less deformable than passive PMN, and the pseudopods showed very little membrane deformation. The increased number of rigid active and immature neutrophils may contribute to impaired microcirculation and the high risk for organ injury in septic patients.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

This study examined the hypothesis that the cerebrovascular response to asphyxia of the late gestation sheep fetus is characterized by an increase in cerebrovascular resistance and a fall in cerebral blood flow (CBF) rather than the fall in resistance and increase in CBF which occurs in acute hypoxemia. In eight unanesthetized late gestation fetal sheep (123- to 125-d gestation) we evaluated continuous changes in carotid blood flow (CaBF) as an index of global CBF and total cerebral Hb concentrations as an index of global cerebral blood volume (CBV) using ultrasound flow probes and near infrared spectroscopy respectively. Asphyxia was induced by rapid and complete occlusion of the umbilical cord for 10 min. We also examined the fetal response to 1 h of acute 9% isocapnic hypoxia for comparison purposes. During hypoxia we observed a sustained increase in CaBF (p< 0.05) and CBV (p< 0.01) and a fall in carotid vascular resistance (p< 0.05). During asphyxia there was no significant rise in CBV, a fall in CaBF (p< 0.05), and a rise in carotid vascular resistance (p< 0.01). CaBF fell at a time when mean arterial pressure was elevated (p< 0.01). These data strongly suggest that fetal CBF does not increase and may even fall during severe asphyxia of rapid onset. Furthermore, our near infrared spectroscopy data show that the relative changes in total cerebral Hb concentrations may reflect the type and severity of the insult to which the fetus is exposed.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID