Dexmedetomidine-mediated neuroprotection against sevoflurane-induced neurotoxicity extends to several brain regions in neonatal rats.

BACKGROUND: Exposure of infant animals to clinically used anaesthetics is associated with acute structural brain abnormalities and development functional alterations. The α 2 -adrenoceptor agonist dexmedetomidine (DEX) induces sedation, analgesia, and provides neuroprotection in experimental brain injury models. However, it is unknown whether DEX also affords protection in the developing brain against anaesthesia using sevoflurane (SEVO), which is commonly used in paediatric anaesthesia. METHODS: Infant rats were exposed on postnatal day seven for six h to 2.5% SEVO and were given i.p. injections of saline or DEX (1-50 µg kg -1 ) three times during the exposure. Level of anaesthesia, respiratory rates, and arterial blood gasses were assessed for each animal. Apoptosis was determined in brain slices immunostained for activated caspase-3 (AC-3) using a computerised approach. RESULTS: SEVO alone induced a surgical plane of anaesthesia, and all animals survived the study. SEVO induced an approximately 10-fold increase in AC-3 positive cells in several cortical and subcortical brain regions compared with untreated control animals. Co-administration of DEX 1 µg kg -1 with SEVO significantly reduced apoptosis in all brain areas, affording the highest protection in the thalamus (84% reduction) and lowest in the hippocampus and cortical areas (∼50% reduction). DEX 5-25 µg kg -1 plus SEVO dose-dependently increased infant rat mortality. CONCLUSIONS: SEVO anaesthesia induced widespread apoptosis in infant rat brain. Co-administration of DEX (1 µg kg -1 ) provided significant protection, whereas DEX (5 µg kg -1 or higher) plus SEVO increased mortality. Our findings suggest that DEX could be an attractive therapeutic for future studies investigating its neuroprotective potential in a translational animal model.

[Mission and tasks of the Coordination Centres for Clinical Trials]. / Aufgaben der Koordinierungszentren für Klinische Studien.

Coordination Centres for Clinical Trials (Koordinierungszentren für Klinische Studien, KKS) were set up to increase the quality and number of clinical trials in Germany as well as to establish clinical trial training programs in order to improve international recognition of German clinical research. Over the past 6 years, 12 KKS have been set up at the respective universities with a public grant from the Federal Ministry of Education and Research (BMBF). Many non-clinical services have been established to ensure successful co-operation in clinical trials with clinical scientists and industry. KKS help researchers to efficiently conduct commercial and non-commercial clinical trials in various disease areas. Their expertise and infrastructure allow the university to assume sponsor responsibility in non-commercial drug trials. Because of their professional work and education activities KKS are well accepted by industry and the scientific community. Central professional trial organisations such as the KKS have been shown to be the pre-requisite for meeting the growing, manifold and complex requirements for clinical trials. Therefore they are considered essential for progress and success in clinical research.

Tie2 receptor expression is stimulated by hypoxia and proinflammatory cytokines in human endothelial cells.

The tyrosine kinase receptor Tie2 (also known as Tek) plays an important role in the development of the embryonic vasculature and persists in adult endothelial cells (ECs). Tie2 was shown to be upregulated in tumors and skin wounds, and its ligands angiopoietin-1 and -2, although they are not directly mitogenic, modulate neovascularization. To gain further insight into the regulation of Tie2, we have studied the effect of hypoxia and inflammatory cytokines, two conditions frequently associated with neoangiogenic processes, on Tie2 expression in human ECs. Exposure to 1% O(2) led to a time-dependent significant rise of Tie2 protein levels in human coronary microvascular endothelial cells (HCMECs) and dermal microvascular ECs (HMEC-1) (3.2- and 2.5-fold within 24 hours), which was reversible after reoxygenation, and induced a less marked increase in human umbilical vein ECs (HUVECs; 1.7-fold). Hypoxia-conditioned medium and D-deoxyglucose did not change Tie2 expression, but desferrioxamine and cobalt, which are known to mimic hypoxia-sensing mechanisms, induced Tie2 at ambient oxygen tensions. Tumor necrosis factor-alpha induced Tie2 in a time- and dose-dependent fashion in all 3 EC types (HUVEC, 2.3-fold; HMEC-1, 2. 8-fold; and HCMEC, 3.0-fold; 10 ng/mL, 24 hours). Enhanced expression was also found after exposure to interleukin-1beta (1 ng/mL). Changes in Tie2 protein levels were paralleled by changes in mRNA expression. In accordance with these in vitro findings, immunohistochemistry revealed focal upregulation of Tie2 in capillaries at the border of infarcted human and rat myocardium. In conclusion, the data show that hypoxia and inflammatory cytokines upregulate Tie2, which may contribute to the angiogenic response in ischemic tissues.

WITHDRAWN: Non-invasive Estimation of Left Ventricular End-diastolic Pressure by Pulmonary Venous Flow Deceleration Time.

The publisher regrets that this was an accidental duplication of an article that has already been published in Eur. J. Echocardiogr., 4 (2003) 162-168, . The duplicate article has therefore been withdrawn.

The adhesive properties of recombinant soluble L-selectin are modulated by its glycosylation.

The leukocyte adhesion molecule L-selectin, which mediates the initial steps of leukocyte attachment to vascular endothelium, is intensely glycosylated. Different glycoforms of L-selectin are expressed on different leukocyte subsets and differences in L-selectin glycosylation appear to be correlated with the leukocyte's ability to attach to different endothelial targets. In the present study we addressed the question whether glycosylation of L-selectin influences L-selectin-ligand interactions. To obtain different glycoforms of L-selectin, recombinant proteins were expressed both in the baby hamster kidney (BHK) cell line and in the human myelogenous cell line K562, resulting in sL-sel[BHK] or sL-sel[K562], respectively. The glycosylation characteristics of the purified proteins were determined. The most striking differences in glycosylation were seen in the terminal sialylation. Each of the two proteins carried sialic acids in the alpha 2-3 position, while alpha 2-6-bound sialic acids were found exclusively on sL-sel[K562]. To investigate their adhesive properties, both recombinant sL-selectins were used in cell adhesion assays and interactions with the ligands present on various hematopoietic cell lines or activated human cardiac microvascular endothelial cells were examined. The binding capacity of sL-sel[K562] was about 1.6 fold higher compared to sL-sel[BHK] under static as well as under flow conditions. These findings indicate that the terminal sialylation pattern of L-selectin modulates its binding characteristics.

Recurrent chiasmatic-hypothalamic glioma treated with oral etoposide.

PURPOSE: Chiasmatic-hypothalamic gliomas are not amenable to surgical resection and therefore are treated with either radiotherapy or chemotherapy. Here we report the use of etoposide (VP-16) administered on a chronic oral schedule as a novel chemotherapeutic approach. PATIENTS AND METHODS: Fourteen patients, aged 2 to 15 years, were treated with VP-16 after clinical and neuroradiographic tumor progression. Thirteen patients had received prior radiotherapy, and 12 received prior nitrosourea-based chemotherapy. VP-16 was administered orally, each cycle consisting of 50 mg/m2/d on day 1 through 21 and 36 through 57. Clinical and neuroradiographic evaluations were performed during days 58 through 72 before initiation of each cycle of therapy. Complete blood counts were performed weekly. RESULTS: Treatment-related complications included the following: partial alopecia (seven patients); diarrhea (six); weight loss (five); neutropenia (four); and thrombocytopenia (four). Three patients required transfusion (three RBC; two platelet), and one patient required antibiotic treatment of neutropenic fever. There were no treatment-related deaths. Fourteen patients were assessable, five of whom demonstrated a radiographic response (one complete and four partial); and three patients demonstrated stable disease, with a median duration of response of 8 months. CONCLUSION: Chronic oral VP-16 is well tolerated, produces modest toxicity, and has apparent activity in this small cohort of patients with recurrent chiasmatic-hypothalamic gliomas.

Adenovirus-mediated overexpression and stimulation of the human angiotensin II type 2 receptor in porcine cardiac fibroblasts does not modulate proliferation, collagen I mRNA expression and ERK1/ERK2 activity, but inhibits protein tyrosine phosphatases.

The contribution of the angiotensin (Ang) II type 2 receptor (AT2R) to cardiac hypertrophy is still controversial. Here we examined the effect of overexpressing the human AT2R in cultured porcine cardiac fibroblasts (pFib) on proliferation, procollagen I mRNA expression, and - as putatively underlying signal-transduction pathways - on mitogen-activated protein kinase ERK1/ERK2 and phosphotyrosine phosphatase activities. As quantitated by 125I-(Sar1,Ile8)-Ang II binding, transduction of cardiac fibroblasts with the adenoviral AT2R expression vector led to a six- to tenfold higher AT2 than endogenous Ang II type 1 receptor (AT1R) expression. The overexpressed AT2R had the same apparent molecular mass as the endogenous AT2R in rat PC12W cells. Proliferation was not significantly lower in AT2R expressing pFib than in antisense-transduced controls (TA2) upon stimulation with Ang II (AT2R 110.5+/-4.8% vs. TA2 110.2+/-5.5%), Ang II plus the AT1R blocker Irbesartan (97.1+/-1.4% vs. 108.0+/-5.0; P=0.052) and the partial AT2R antagonist CGP42112 at the agonistic concentration of 50 nM (92.1+/-2.7% vs. 99.8+/-3.1%; P=0.053). Procollagen Ialpha2 (COL1A2) mRNA levels were quantitated by (a) northern blot analysis and (b) reverse transcriptase polymerase chain reaction. COL1A2/GAPDH (a) and COL1A2/beta-actin (b) ratios revealed no differences between AT2R-transduced fibroblasts and antisense controls when stimulated with Ang II (1 microM, 24 h) plus Irbesartan and 10 ng/ml transforming growth factor beta1. Ang II stimulation of the endogenous AT1R increased extracellular signal regulated kinase 1/2 activities. This response was reduced by Irbesartan, but PD123319 had no effect. Time course and magnitude of Ang II stimulated ERK1/ERK2 activation was identical in AT2R-transduced and control cells. Also, neither simultaneous nor Ang II pre-stimulation, suggested to induce gene expression of the MAP kinase phosphatase 1, modulated phorbol myristate acetate-stimulated ERK1/ERK2 activation in AT2R-transduced pFib, in AT2R-transduced human umbilical vein endothelial cells, and in PC12W cells. By the use of a tyrosine phosphatase assay we observed an inhibition of phosphotyrosine phosphatase activity by 30.8% (P=0.009, n=5) after 5 min Ang II stimulation of AT2R-expressing pFib. Immunoprecipitation-tyrosine phosphatase assays revealed that inhibition of phosphotyrosine phosphatase 1B, which regulates insulin signaling, contributed to this effect. In conclusion, stimulation of the overexpressed human AT2R in porcine cardiac fibroblasts inhibited tyrosine phosphatase activity but had no significant effect on fibroblast functions related to cardiac fibrosis. It is conceivable that possible antifibrotic AT2R effects are species specific and/or require the interaction between fibroblasts and cardiomyocytes, probably via paracrine factors, or mechanical load.

ACE inhibitors are endothelium dependent vasodilators of coronary arteries during submaximal stimulation with bradykinin.

OBJECTIVE: The effect of angiotensin converting enzyme (ACE) inhibitors on vascular tone of isolated coronary arteries was determined in the presence of bradykinin and other vasodilators to elucidate the mechanisms leading to augmented bradykinin effects during ACE inhibition. METHODS: Rings of isolated bovine and human coronary arteries were mounted in organ chambers for measurement of isometric force. The effects of lisinopril, enalaprilat, and captopril were investigated in the presence of submaximal concentrations of bradykinin or other vasodilators. RESULTS: ACE inhibitors alone did not affect vascular tone. Threshold concentrations of bradykinin (10(-10) M), kallidin (10(-9.5) M), and the slowly degraded bradykinin agonists D-Arg(Hyp3)-bradykinin (10(-9.5) M) and [Hyp3-Tyr(Me)8]-bradykinin (10(-10.5) M) caused partial relaxation of bovine rings with endothelium. Subsequent addition of ACE inhibitors markedly potentiated the relaxations to the kinins. Bradykinin concentrations in the organ bath measured by a specific bradykinin radioimmunoassay remained stable during the addition of lisinopril. Variation of the exposure time to bradykinin (10 to 60 min) did not affect the relaxations to the ACE inhibitor. The relaxations to lisinopril were not observed after either removal of the endothelium or incubation with nitro-l-arginine or the bradykinin-2 receptor antagonist Hoe 140. Other vasodilators including acetylcholine, adenosine diphosphate, substance P, or SIN-1 did not prime the rings to respond to ACE inhibitors. Endothelium dependent relaxation to lisinopril and captopril was also observed in human coronary arteries treated with bradykinin (> or = 10(-7) M), but not in those treated with substance P (10(-8) M). CONCLUSIONS: ACE inhibitors selectively potentiate endothelium dependent relaxations to submaximal concentrations of bradykinin in bovine and human coronary arteries by a local mechanism. This effect on endothelial cells might occur in addition to augmented bradykinin concentrations in the blood and reduced angiotensin II generation.

The correlation of prenatal brain damage with placental pathology.

Several epidemiological studies have emphasized that prenatal factors are the best predictors for cerebral palsy. Many placental pathologists have anecdotally recognized an association between placental pathology and poor pregnancy outcome, including neurologic injury. This study was undertaken to determine if correlations exist between specific types of placental pathology and prenatal brain injury. Ninety-eight stillbirths and livebirths with < 1 hour survival and complete placental and neuropathologic exams were reviewed. Most brain damage was in three categories: germinal matrix/intraventricular hemorrhage (GMH), white matter gliosis/necrosis (WMG/N), and neuronal necrosis. Statistical analysis of contingency tables showed significant associations of WMN with placental chronic vascular changes (PCV), umbilical cord problems, old infarction/abruptio, and meconium staining of the placenta. Associations were found between neuronal necrosis and PCV, surface vessel thrombosis, and old infarction/abruptio. GMH was associated with funisitis, but no other factors. Fetuses with WMN or neuronal necrosis were older than fetuses with GMH or no neuropathology. It is likely that these types of placental pathology can also be correlated with prenatal brain injury in liveborn infants, and examination of the placenta may indicate which infants are at greater risk for neurologic injury.

Successful silver impregnation of degenerating axons after long survivals in the human brain.

Degenerating axons in the human brain were successfully impregnated with reduced silver methods. The appearance of degenerating fibers did not differ markedly with survival times of three weeks and two, six, and twelve years following cerebral infarction or contusion of the brain. Impregnated fibers were found only along the appropriate corticofugal pathways. Electron microscopic examination of Vibratome-cut, silver-stained sections demonstrated silver deposition almost exclusively within axon fragments. Previous studies using anterograde degeneration methods in the human brain have limited their choice of cases to those with short periods of survival. Relaxing the restriction of short survival times extends the range of cases which can be used to study neural connections which may be unique to, or different in, the human brain.

Immunocytochemical studies of substance P and Met-enkephalin in the basal ganglia and substantia nigra in Huntington's, Parkinson's and Alzheimer's diseases.

Immunocytochemical studies of the distribution and intensity of Substance P and Met-enkephalin staining in the basal ganglia and substantia nigra were carried out in five cases each of brains from patients with Huntington's disease, Parkinson's disease, Alzheimer's disease, and normal controls. The usefulness of the peroxidase-antiperoxidase method for human autopsy material was confirmed. Substance P and Met-enkephalin fibers were distributed in essentially the same pattern as described in experimental animals and in human brains. In Huntington's disease brains decreased Substance P staining was found in the internal globus pallidus and the substantia nigra, in agreement with radioimmunoassay studies by others. Met-enkephalin staining in the external globus pallidus was of normal intensity, although present within a shrunken area. In Parkinson's and Alzheimer's diseases there was intense immunoreactivity for Substance P in the globus pallidus and substantia nigra, and for Met-enkephalin in the globus pallidus, at variance with reported decreases in Parkinson's disease by radioimmunoassay, but in essential agreement with other immunocytochemical studies. Immunocytochemical methods complement radioimmunoassays of human brain and may help in mapping neuropeptidergic pathways and in pinpointing abnormalities in these pathways in basal ganglia disorders.

Case of the month: January 1999--Fetus with echogenic mass in third ventricle.

A 29-week gestational age newborn male infant was found to have an echogenic mass in the 3rd ventricle by prenatal ultrasound 2 weeks prior to delivery. At delivery he was poorly responsive and had hydrocephalus and ascites. A CT scan after birth showed cerebral infarction, amorphous tissue in the left hemisphere and numerous calcifications. Despite supportive treatment he died 4 days after birth. Postmortem examination of the brain revealed marked distortion of the architecture and a supratentorial undifferentiated neoplasm consistent with a PNET. The tumor showed extensive areas of hemorrhage and necrosis and involvement of lateral and third ventricles, brain parenchyma, and meninges.

Regulation and differential expression of neutral endopeptidase 24.11 in human endothelial cells.

Neutral endopeptidase 24.11, a membrane-bound metallopeptidase, cleaves, and degrades vasoactive peptides such as atrial natriuretic peptide, endothelin, angiotensin I, substance P, and bradykinin. Therefore, the presence of this metallopeptidase may contribute to the regulation of vascular tone and local inflammatory responses in the vascular endothelium and elsewhere. We determined neutral endopeptidase in cultured human endothelial cells from different vascular beds and studied its regulation by protein kinase C. Neutral endopeptidase was detected in all cultured endothelial cell types. Lowest concentrations were measured in human endothelial cells from umbilical veins (360 +/- 14 pg/mg protein), followed by pulmonary and coronary arteries; higher concentrations were found in endothelial cells from the cardiac microcirculation (1099 +/- 73 pg/mg protein). Neutral endopeptidase content increased during cell growth but was not affected by endothelial cell growth factor or modifications of the growth medium. Stimulation of protein kinase C with 1-oleoyl-2-acetyl-rac-glycerol (0.1 to 1 mumol/L) and phorbol 12-myristate 13-acetate (0.01 to 0.1 mumol/L) induced a time- and concentration-dependent increase of endothelial cells that was inhibited by cycloheximide (5 mumol/L), an inhibitor of protein synthesis. Incubation with phospholipase C (1 mumol/L) and thrombin (10 IU/mL) induced upregulation of neutral endopeptidase, resulting in 158 +/- 26% and 150 +/- 22% increases, respectively, compared with controls. The thrombin effect was inhibited by calphostin C (1 mumol/L), an inhibitor of protein kinase C. Endothelial neutral endopeptidase is constitutively expressed in endothelial cells from different origins and is inducible by thrombin via activation of the protein kinase C pathway.

MK-801, an excitatory amino acid antagonist, does not improve neurologic outcome following cardiac arrest in cats.

The excitatory amino antagonist MK-801 was administered to cats following resuscitation from cardiac arrest to evaluate its effect on neurologic and neuropathologic outcome in a clinically relevant model of complete cerebral ischemia. In 29 cats studied, cardiac arrest (ventricular fibrillation) was maintained for 18 min and resuscitation was successfully performed in 21 cats. Four animals underwent a sham arrest. MK-801 or placebo was administered in a blinded, randomized manner. Beginning at 5 min post resuscitation (PR), MK-801 330 micrograms/kg over 2 min followed by 73 micrograms/kg/h for 10 h or the same volume of placebo was administered. Resuscitated animals remained paralyzed and sedated in an intensive care setting for 24-30 h PR. Neurologic examinations were performed at 2, 4, and 7 days PR by observers blinded to the treatment groups. Seventeen cats were entered into data analysis (nine MK-801-treated and eight placebo-treated). MK-801-treated animals had a significantly greater neurologic deficit score (NDS) rank (0 = normal, 100 = brain death) 2 days PR (mean rank 12.1 vs. 5.6; p = 0.008). This difference is most likely due to ongoing sedative actions of MK-801. There were no significant differences in NDS rank at 4 (10.3, MK-801 vs. 7.5, placebo) and 7 (9.6, MK-801 vs. 8.3, placebo) days PR. There were no significant differences in frontal cortex, hippocampus, occipital cortex, or cerebellar neuropathology between groups. Sham-arrested cats had normal neurologic and neuropathologic evaluations. In the circumstance of complete cerebral ischemia as employed in the current study, MK-801 had no beneficial effect upon neurologic or neuropathologic outcome.

Human cardiac microvascular and macrovascular endothelial cells respond differently to oxidatively modified LDL.

Oxidation of low density lipoproteins (LDL) is considered a key event in the pathogenesis of atherosclerotic lesions. Disturbed generation of coagulatory and anticoagulatory factors by endothelial cells contributes to thrombosis and the progression of atherosclerosis in coronary arteries. In this study, the effects of native LDL (n-LDL) and oxidized LDL (ox-LDL) on human coronary endothelial cells were measured. The reaction of coronary endothelial cells to LDL were compared with those of cardiac microvascular endothelial cells grown under comparable conditions. LDL was isolated by ultracentrifugation and copper oxidized. The degree of oxidation was expressed as malondialdehyd (MDA) equivalents and was 0.78+/-0.14 nM MDA/mg LDL for native LDL and 13.63+/-1.18 nmol MDA/mg LDL for ox-LDL. Basal secretion of t-PA and PAI-1 activity were higher in macrovascular endothelial cells. Incubation of n-LDL in concentrations ranging from 3 to 100 microM/ml LDL-protein did not change t-PA-secretion, PAI-1 activity or procoagulant activity in both cell types. Ox-LDL (3 to 100 microM/ml LDL protein) decreased t-PA secretion in a concentration dependent manner from 30.9+/-1.7 to 13.7+/-30 ng/ml per 24 h per 10(6) cells (P < 0.01), increased PAI-1 antigen from 2772+/-587 to 4441+/-766 ng/ml per 24 h per 10(6) cells (P < 0.05) as well as PAI-1 activity from 34+/-6 to 55+/-9 AU/ml per 24 h per 10(6) cells (P < 0.05) in macrovascular endothelial cells but had only minor effects on microvascular endothelial cells. Procoagulant activity measured as coagulation time, similarly increased only in macrovascular endothelial cells from 197+/-6 to 76+/-6 s/24 h per 10(6) cells (P < 0.05). The effect on PAI-1 secretion showed a dependency to the degree of oxidation and could be completely blocked by the antioxidant probucol. The angiotensin converting enzyme (ACE), which represents an endothelial enzyme not related to coagulation, remained unchanged during incubation with ox-LDL. Basal ACE activity was higher in microvascular endothelial cells. The higher susceptibility of macrovascular endothelial cells to ox-LDL may partially determine the localization of thrombus formation and the development of atherosclerotic plaques in hyperlipidemic patients.

Occurrence of prosaposin as a neuronal surface membrane component.

Prosaposin is a precursor of four saposins that are required for the lysosomal hydrolysis of sphingolipids by specific hydrolases. Besides its precursor role, prosaposin also exists as a secreted protein. The present investigation reveals that prosaposin also exists as an integral component of the surface membranes of neuronal cells. Subcellular fractionation studies demonstrate that the membrane-bound prosaposin occurs specifically in plasma membranes of NS20Y rat neuroblastoma cells. An immunohistochemical study of the neuroblastoma cells using rat prosaposin-specific antibodies also showed that a portion of prosaposin is located on the surface of neurites as well as on cell bodies. Similar histochemical studies with antibodies that specifically recognized human prosaposin revealed the presence of prosaposin in dendrites, axons, and cell bodies of subcortical and spinal cord neurons in both human adult brain and in fetal brain (24-wk gestation). These findings suggest an important role of prosaposin in neuronal development.

Activation of adenylate cyclase and phosphodiesterase inhibition enhance neutral endopeptidase activity in human endothelial cells.

Endothelial neutral endopeptidase (EC 3.4.24.11, NEP) contributes to the inactivation of vasoactive and inflammatory peptides such as f-Met-Leu-Phe, substance P, atrial natriuretic peptide, and bradykinin. The aim of the present study was to investigate the cellular regulation of NEP expression in human endothelial cells, focusing on the role of cyclic nucleotides and cellular phosphodiesterases (PDE). Activation of adenylate cyclase by forskolin or prostaglandin E1 (PGE1) induced an increase of NEP activity and NEP protein after 24 h of incubation. This effect was mimicked by two activators of protein kinase A, dibutyryl-cAMP and 8-bromo-cAMP. The nonspecific PDE inhibitor, 3-isobutyl-1-methylxanthine (200 microM), increased NEP activity up to 192%. The activator of guanylate cyclase, sodium nitroprusside (SNP), did not affect NEP activity but completely inhibited the 3-isobutyl-1-methylxanthine-mediated increase of NEP activity. The PDE-III inhibitors motapizone (100 microM) and enoximone (100 microM) enhanced NEP activity up to 188% and 213%, the PDE-IV inhibitor rolipram (3 microM) up to 162%, and the combined PDE-III/IV inhibitor zardaverine (1 microM) up to 176% of control values. The present data provide evidence for a cAMP-mediated increase of NEP activity in human endothelial cells.

Histopathologic consequences of hyperglycemic cerebral ischemia during hypothermic cardiopulmonary bypass in pigs.

BACKGROUND: This study examined whether 34 degrees C or 31 degrees C hypothermia during global cerebral ischemia with hyperglycemic cardiopulmonary bypass (CPB) in surviving pigs improves electroencephalographic (EEG) recovery and histopathologic scores when compared with normothermic animals. METHODS: Anesthetized pigs were placed on CPB and randomly assigned to 37 degrees C (n = 9), 34 degrees C (n = 10), or 31 degrees C (n = 8) management. After increasing serum glucose to 300 mg/dL, animals underwent 15 minutes of global cerebral ischemia by temporarily occluding the innominate and left subclavian arteries. Following reperfusion, rewarming, and termination of CPB, animals were recovered for 24 (37 degrees C animals) or 72 hours (34 degrees C and 31 degrees C animals). Daily EEG signals were recorded, and brain histopathology from cortical, hippocampal, and cerebellar regions was graded by an independent observer. RESULTS: Before ischemia, serum glucose concentrations were similar in the 37 degrees C (307+/-9 mg/dL), 34 degrees C (311+/-14 mg/dL), and 31 degrees C (310+/-15) groups. By the first postoperative day, EEG scores in 31 degrees C animals (4.2+/-0.6) had returned to baseline and were greater than those in the 34 degrees C (3.4+/-0.5) and 37 degrees C (2.5+/-0.4) groups (p < 0.05, respectively, between groups). Cooling to 34 degrees C showed selective improvement over 37 degrees C in hippocampal, temporal cortical, and cerebellar regions, but the greatest improvement in all regions occurred with 31 degrees C. Cumulative neuropathology scores in 31 degrees C animals (13.5+/-2.2) exceeded 34 degrees C (6.8+/-2.2) and 37 degrees C (1.9+/-2.1) animals (p < 0.05, respectively, between groups). CONCLUSIONS: Hypothermia during CPB significantly reduced the morphologic consequences of severe, temporary cerebral ischemia under hyperglycemic conditions, with the greatest protection at 31 degrees C.

Developmental changes in the sensitivity of the neonatal rat brain to hypoxic/ischemic injury.

Developmental changes in the response of the neonatal rat brain to hypoxic/ischemic injury were examined. Hypoxic/ischemic injury was produced by unilateral carotid ligation followed by exposure to hypoxia in 1- (D1), 3- (D3), 5- (D5) and 7-day-old (D7) rats. Injury was produced in most D7 animals exposed to > or = 120 min of 7.6 or 8% oxygen after carotid ligation. The extent of neuronal injury was variable, ranging from focal neuronal death to massive infarction. In D5 and D3 animals, there was a progressive decline in the extent of neuronal injury in response to hypoxia/ischemia. In the younger animals, bilateral injury was occasionally seen. Sham-operated animals exposed to hypoxia alone had numbers of karyorrhectic neurons similar to normal control animals in all age groups. The underlying developmental changes which account for these differences are not yet known but are likely to be multiple.

Developmental changes in the topographical distribution of cells contributing to the lateral olfactory tract.

Developmental changes in the locations of cells in the olfactory bulb which contribute axons to the lateral olfactory tract (LOT) were investigated using retrograde transport of horseradish peroxidase (HRP). HRP was placed in the olfactory tubercle, LOT, and/or piriform cortex of golden hamsters aged 3,7,8 and 20 days. The numbers of labeled mitral and tufted cells were counted on equidistant sections through the olfactory bulb. In the younger animals (days 3 and 7), there was a distinct localization of labeled cells in the medial quadrant of the bulb. In the 3-day-old group 49% of all labeled cells were located in the medial quadrant, but by day 8 the per cent of cells in all 4 quadrants was equivalent. Between days 3 and 20, the average perimeter of the mitral cell layer doubled. There was a similar increase in the average relative total number of labeled cells per bulb. When pairs of brains from the different age groups with HRP placements of similar size and location were compared, the older brain always had more labeled cells. There was no relation of the number or distribution of labeled cells to the location of the injection. The number of labeled cells correlated positively with the size of the injection within each age group. We believe this is the first report of a developmental topographical gradient of the cells of origin of the LOT. This localization may be related to early topographical differences in functional activity which reflect a limited exposure to odors in the first week of life.