The development of cerebral perfusion in healthy preterm and term neonates

Quantitative measurement of cerebral blood flow (CBF) volume was performed by sonographic flowmetry of both internal carotid (ICA) and vertebral arteries (VA) in 113 healthy preterm and term infants of 32 - 42 weeks postmenstrual age (PA) in order to delineate the physiological characteristics of brain perfusion in a time period very sensitive to brain injury. Mean CBF volume increased with PA, beginning with 33 +/- 9 ml/min in neonates of 32 - 34 weeks and rising to 45 +/- 10, 58 +/- 13, 69 +/- 14, and 83 +/- 16 ml/min, respectively, in the PA groups of 35 - 36, 37 - 38, 39 - 40 and 41 - 42 weeks. There was no difference in CBF volume between the sexes. The bilateral sum of flow volumes in both ICA and VA rose markedly with PA. The relative contribution of bilateral VA flow volume to total CBF volume was 26 +/- 8 % and remained constant with PA. In addition, we calculated the approximate CBF (ml/100 g brain weight/min) using the brain weights of each child as estimated by means of an equation based on head circumference measurements. Estimated CBF correlated significantly with PA (r = 0.49; p 相似文献   

Factors influencing astrocyte growth and development in defined media

A previously described serum-free, defined medium (G2 medium) containing transferrin, selenium, hydrocortisone, biotin, fibroblast growth factor (FGF) and fibronectin developed for the growth of human and rat derived glioma cells was investigated for its ability to support proliferation of astrocytes in primary cultures of neonatal rat cerebrum. These cells were able to grow in G2 medium. Enhanced proliferation and repeated subcultivation were obtained after adding insulin and/or epidermal growth factor (EGF) to the G2 medium at concentrations of 5 μg/ml and 10 ng/ml, respectively.

In these modified media (called G4 and G5 medium) astrocytes showed a higher degree of morphological differentiation as compared to serum supplemented medium. Cell type specificity was determined by immunocytochemical staining of glial fibrillary acidic (GFA) protein, which could already be demonstrated 5 days after plating cells. G4 and G5 represent the first serum-free defined media in which astrocytes proliferate and differentiate without preceding or intermediate contact to serum supplemented medium. Modification of the culture substratum by adding hyaluronic acid and chondroitin sulfate A to G4 medium (G2 medium + insulin) enhanced proliferation of astroglial cells by a factor of about 1.5. In the presence of epidermal growth factor no response to the altered culture dish surface was observed and the addition of fibronectin, otherwise a stringent plating requirement, was no longer necessary.     

Factors influencing the response of the cerebral circulation to phenylethylamine.

The cerebrovascular actions of phenylethylamine, an amine that has been implicated in the pathogenesis of migraine, were investigated in 16 anesthetized baboons. The influence of monoaminergic blocking agents and of a specific inhibitor of monoamine oxidase upon the cerebral circulatory and metabolic actions of phenylethylamine were examined. The reductions in cerebral blood flow (28 percent) and cerebral oxygen consumption (31 percent) that accompany the intracarotid administration of phenylethylamine (2 X 10(-6) moles per kilogram per minute) were unaffected by the prior administration of either phenoxybenzamine (1.5 mg per kilogram, IV) or pimozide (0.5 mg per kilogram, IV). The administration of phenoxybenzamine and pimozide per se did not significantly disturb cerebral blood flow or oxygen consumption. The ability of migraine patients to oxidatively deaminate phenylethylamine is reduced at the time of their attacks. In the present experiments, the administration of the monoamine oxidase type B inhibitor, deprenyl (1 mg per kilogram, IV), did not effect significant changes in cerebral blood flow or cerebral oxygen consumption. However, following deprenyl, the administration of phenylethylamine (4 X 10(-8) moles per kilogram per minute), a concentration which was without effect in normal animals, significantly reduced cerebral blood flow. Some of the possible mechanisms influencing the sensitivity of the cerebral circulation to phenylethylamine, and their relationship to migraine, are considered.     

Factors influencing the motor development of prematurely born school-aged children in Brazil

Despite technological advances in neonatology, premature children are still susceptible to disruptions in neurological development. The current study aimed to analyze the factors that influence motor development in prematurely born school-aged children in Brazil. This cross-sectional study involved 100 “apparently normal” children, aged 8–10 years, born at less than 35 weeks of gestation or with birth weight < 1500 g. Their motor development was assessed using the Movement Assessment Battery for Children (MABC-2). The children's neuropsychological and academic performance was assessed with the Token Test (TT) and Teste de Desempenho Escolar (TDE), respectively. Parents answered questions regarding the child's clinical history and behavior using the Strengths and Difficulties Questionnaire (SDQ) and family environment resources (RAF). Hierarchical multivariate analyses revealed that 39% of the children scored lower on the MABC-2, as compared to that expected for their age (manual dexterity: 49%; balance: 35%; throwing/catching a ball: 26%). Multivariate analysis indicated that the lower the birth weight, the maternal age at childbirth, and the RAF score, the greater was the chance of impairment on the MABC-2 scores. The probability of having an impairment MABC-2 scores was four times higher when the mother was not employed. We also found associations between MABC-2 scores and the tasks of tying shoes and opening/closing zippers and buttons. Factors related to children's home environments and birth weight are associated with deficient motor performance in prematurely born Brazilian school-aged children. Deficient motor skills were also associated with difficulty in performing functional tasks requiring greater manual dexterity.     

Factors influencing the expectations of parents for their mentally retarded children

In terms of treatment for cure, education, training and general information, parental expectations for their mentally retarded children are influenced by various factors such as the age and sex of the retarded child, the level of mental retardation, the education and occupation of the parents, and the socio-economic status and area of living. In the present study, an attempt has been made to find out the correlation of six variables namely, age, sex, literacy, locality of living, level of retardation and duration of follow-up on the expectation of one hundred parents of mentally retarded children who attend the home-based services at the National Institute for the Mentally Handicapped, Secunderabad, India. The intercorrelation among the six independent variables and the dependent variable revealed that age of the child and duration of follow-up have a high correlation (P < 0.01), and literacy of the parents and duration of follow-up were positively correlated (P < 0.05 level). It was also found that age and duration of follow-up have a positive correlation. Further detailed multiple regression analysis was conducted and the results are discussed.     

The role of platelets in the development of cerebral vasospasm.

A possible role of platelet-derived 5-HT was examined concerning the pathogenesis of cerebral vasospasm. Intracisternal injection of 5 ml of platelet-rich plasma (PRP; approximately 7.5 x 10(8) platelets) induced not only acute (1 h) but also chronic (7 days) angiographically evident cerebral vasospasm in dogs. Sympathetic perivascular nerves on cerebral arteries showed no remarkable change following repeated injections of PRP, as the dense distribution of catecholamine-fluorescence and neuropeptide Y-like immunoreactive nerve fibers on Day 7 was comparable to findings in the preinjection controls. While there were no 5-HT-immunoreactive fibers in the cerebral arteries of control animals, numerous 5-HT-immunoreactive fibers were present in the PRP-injected animals. These results suggest that 5-HT, presumably released from extravasated platelets, may be taken up by nerve endings and act as a vasoconstrictor transmitter in the pathogenesis of chronic vasospasm.     

脑灌注压对创伤性脑水肿的影响

目的通过观察不同灌注压(CPP)水平对实验性脑创伤早期脑水肿的影响作用来选择适宜的CPP水平,为临床脑创伤治疗提供参考。方法实验用兔30只,随机分为对照组(无颅脑损伤),高CPP组(90～110mmHg),中CPP组(70～80mmHg),低CPP组(60～70mmHg),和极低CPP组(35～45mmHg)5组,每组6只。对照组不予损伤,其余各组均给予(1100±100)N的撞击力致减速性脑损伤(重伤水平)。伤后80min静脉给予升压药或降压药物调控血压使CPP达到设计要求。伤后6h测脑含水量。结果所有颅脑损伤动物均出现了明显的脑损伤生理反应和病理改变,颅内压(ICP)均明显增高(P<0.001)。脑含水量为:对照组,78.18%±0.32%;高CPP组,81.35%±1.02%;中CPP组,80.27%±0.48%;低CPP组80.31%±0.70%;极低CPP组,81.19%±0.74%。与对照组比较损伤组脑含水量均增加(P<0.001)。高CPP和极低CPP两组脑含水量分别较中、低CPP组增高(P<0.05)。结论兔脑创伤后维持CPP在60～80mmHg之间的中低水平,脑水肿轻;CPP降至50mmHg以下和升至90mmHg以上均加重脑水肿。     

Neuro-imaging of cerebral visual disturbances in children

The present study comprises the neuroradiological examination (computertomography++, magnetic resonance imaging) of 26 children--9 of them were premature, 16 were full-term and in one patient, no details of the pregnancy were known--all suffering from: a) visual disturbance, not caused by ocular disease or afflictions of the optic nerve b) infantile encephalopathy The examination revealed characteristic lesions of the retrochiasmatic part of the visual system. These consisted of white matter abnormalities located periventricularly and just below the striate area, and of grey matter abnormalities of the striate cortex. The demonstration of these abnormalities may advance the diagnosis of the visual handicap and may facilitate early adjustment of developmental stimulation.     

Responses of cerebral arteries to the changes in cerebral perfusion pressure

The responsiveness of cerebral pial arteries and arterioles to changes in systemic arterial blood pressure (SAP) was investigated. Using 9 cats anesthetized with chloralose and urethane, direct, simultaneous measurements of pial arterial pressure (PAP) and cerebral blood flow (CBF) were made during changes in SAP. SAP was varied between 25 and 140 mmHg by the hemorrhage and blood infusion methods. After a partial craniotomy. PAP was measured with a micropipette connected to a servo-controlled micropressure recording system. Punctured pial arteries were grouped into three types according to their diameters, 1A (291 +/- 33 microns), 2A (16 +/- 26 microns), and 3A (70 +/- 10 microns). CBF on the exposed cortex was measured with hydrogen clearance method. The PAPs measured were a linear function of SAP; PAP (1A) = 0.73/SAP-6.6 (r = 0.96), PAP (2A) = 0.62 X SAP-6.6 (r = 0.90), PAP (3A) = 0.61 X SAP-6.4 (r = 0.93). The result indicates that PAPs are entirely dependent on SAP and that SAP induced changes in PAPs are less in the smaller pial arteries. Regional CBF remained constant (55 +/- 4 ml/100 g/min) between 60 and 140 mmHg of SAP. A significant decrease in CBF was observed below 60 mmHg of SAP. Cerebrovascular resistances were calculated segmentally using the following formulas; large vessel resistances (LVR) = (SAP-PAP(1A]/CBF, middle vessel resistance = (PAP (1A)-PAP (3A]/CBF, and small vessel resistance = PAP (3A)/CBF. The changes in LVR, MVR, and SVR were almost identical between 70 and 140 mmHg of SAP. Below 70 mmHg of SAP, SVR showed the greatest decrease in resistance.(ABSTRACT TRUNCATED AT 250 WORDS)