Biomedical subjects

W Zhang

Publications and source records attributed to W Zhang.

At least 469 records · Page 26Linked to original sources

PubMed2000

Increased sensitivity of multidrug-resistant myeloid leukemia cell lines to lovastatin.

Lovastatin, a competitive inhibitor of HMG-CoA reductase, reportedly inhibits proliferation and induces apoptosis of tumor cells with MDR-1 coded P-glycoprotein (Pgp) expression. In this study we investigated the sensitivity to lovastatin of eight myeloid leukemia cell lines: K562, NOMO-1, NB4 and its retinoic acid (RA) resistant subline NB4/RA, and their multidrug-resistant (MDR) sublines: K562/ADR, NOMO-1/ADR, NB4/MDR and NB4/RA/MDR. MTT and apoptosis assays revealed that K562/ADR, NOMO-1/ADR and NB4/RA/MDR were more sensitive to lovastatin than their parental cell lines, while NB4/MDR showed the same level of sensitivity as parental NB4 cells, which already were very sensitive to lovastatin. Significant elevation of transcript levels of HMG-CoA reductase was observed by semiquantitative RT-PCR analysis in more than three lovastatin-sensitive MDR sublines, but not in NB4/MDR compared with the parental cell lines. HMG-CoA reductase mRNA levels were up-regulated more than two-fold by the exposure to lovastatin in all of the parental non-Pgp-expressing cell lines. In NB4/MDR, HMG-CoA reductase mRNA level was elevated to a similar extent as in parental NB4, whereas in three other MDR sublines which showed preferential sensitivity to lovastatin, their HMG-CoA reductase mRNA levels were not significantly elevated after 24- and 48-h treatment with lovastatin. These results indicate a connection between drug resistance and regulation of the mevalonate pathway, and further strengthen the clinical possibility that drug resistant leukemias would be susceptible to treatment with lovastatin.

Apoptosis↗

PubMed2000

Lateral biopsies added to the traditional sextant prostate biopsy pattern increases the detection rate of prostate cancer.

Urologists routinely use the systematic sextant needle biopsy technique to detect prostate cancer. However, recent evidence suggests that this technique has a significant sampling error and data based upon whole-mounted step-sectioned radical prostatectomy specimens using a three-dimensional computer-assisted prostate biopsy simulator suggests that an increased detection rate is possible using laterally placed biopsies. The simulated 10-core biopsy pattern (traditional sextant biopsy cores and four laterally placed biopsies in the right and left apex and mid portion of the prostate gland) was shown to be superior to the traditional sextant biopsy. The objective of this pilot study was to confirm the higher prostate cancer detection rate obtained using the 10-core biopsy pattern in patients. We reviewed data on 35 consecutive patients with a pathologic diagnosis of prostate cancer biopsied by a single urologist using the 10-core biopsy pattern. The frequency of positive biopsy was determined for each core. Additionally, the sextant and 10-core prostate biopsy patterns were compared with respect to prostate cancer detection rate. Of the 35 patients diagnosed with prostate cancer, 54.3%(19/35) were diagnosed by the sextant biopsy only. The 10-core pattern resulted in an additional 45.7%(16/35) of patients being diagnosed solely with the laterally placed biopsies. The laterally placed biopsies had the highest frequency of positive biopsies when compared to the sextant cores. In conclusion, biopsy protocols that use laterally placed biopsies based upon a five region anatomical model are superior to the routinely used sextant prostate biopsy pattern. Prostate Cancer and Prostatic Diseases (2000) 3, 43-46

Journal Article↗

PubMed2000

A novel electrochemical microsensor for the determination of NO and its application to the study of the NO donor S-nitrosoglutathione.

A novel electrochemical microsensor for the determination of NO based on an electropolymerized film of tetraaminophthalocyaninecopper [Cu(TAPc)] was prepared. Its response to NO and its application to the study of an NO donor (S-nitrosoglutathione; GSNO) are also described. The microsensor exhibited an electrocatalytic effect on NO oxidation and showed a low detection limit, high sensitivity and selectivity for NO determination. The oxidation current (measured by differential pulse amperometry) was linear for NO concentrations ranging from 6.2 x 10(-9) to 3.0 x 10(-5) mol L-1 with a calculated detection limit of 4.0 x 10(-9) mol L-1 (S/N = 3) and a linear coefficient of 0.9984. Some endogenous electroactive substances in biological tissues, such as dopamine, 5-hydroxytryptamine and nitrite, at concentrations higher than those in biological systems did not interfere with NO determination. The sensor shows promise for the possible in vivo determination of NO. Using the microsensor, the NO release from the NO donor (GSNO) was successfully monitored. This work sets a foundation for the study of the pharmacology and the biological effects in vivo of S-nitrosothiols.

Electrochemistry↗

PubMed2000

Speciation of gold(III)-L-histidine complex: a multi-instrumental approach.

The formation and structure of gold (III)-L-histidine complex was investigated with the use of carbon (13C) and proton (1H) nuclear magnetic resonance (NMR), infrared (IR) spectroscopy, capillary electrophoresis (CE), capillary electrophoresis-inductively coupled plasma-mass spectroscopy (CE-ICP-MS), X-ray fluorescence spectroscopy (XRF), matrix-assisted laser desorption/ionization (MALDI), and laser desorption mass spectroscopy (LDMS). It was found that two L-histidine molecules and one gold ion slowly form a complex in acidic solution. Each L-histidine molecule provided two nitrogen ligands; one was the alpha-amino group and the other from the imidazole ring. The Au(III)-bis-L-histidine complex precipitates after deprotonation of the free carboxylic group, resulting in an increase in the solution acidity. Determination of the exact sequence of events and the identity of the complex was a comprehensive instrumental analysis problem involving the above techniques.

Chemical Precipitation↗

PubMed2000

Measurement of nitric oxide released in the rat heart with an amperometric microsensor.

Nitric oxide (NO) plays an important role in various physiological processes, acting either as an intra- and intercellular messenger or as a toxic agent. The detection and quantification of NO have been accomplished by a variety of methodologies. In the present study, real-time production of NO in the rat heart was continuously measured by using a novel copper-platinum microparticle-modified NO electrochemical microsensor. The linearity range of the microsensor is between 8.0 x 10(-8) and 4.8 x 10(-6) mol L-1 and the detection limit is 3.0 x 10(-8) mol L-1. NO release from the rat heart stimulated by the agonists L-arginine and acetylcholine was observed, and the responses were decreased by the NO synthase inhibitor L-N omega-nitroarginine. In addition, the effect of sodium nitroprusside (SNP), a NO donor, was also studied. SNP increases the concentration of NO in the rat heart. The experiments showed that electrochemical detection is suitable for detecting and quantifying NO in biological systems.

Acetylcholine↗

PubMed2000

Neutrophil lactoferrin release induced by IgA immune complexes differed from that induced by cross-linking of fcalpha receptors (FcalphaR) with a monoclonal antibody, MIP8a.

The human IgA Fc receptor (FcalphaR, CD89) plays an important role in host defence against invading pathogens. To study the properties of the receptor, 12 MoAbs, namely, MIP7c, MIP8a, MIP9a, MIP10c, MIP11c, MIP14b, MIP15b, MIP38c, MIP59c, MIP65c, MIP68b and MIP71a, were generated. The inhibitory effects of the antibodies on FcalphaR functions were tested. Three of the antibodies, MIP7c, MIP8a and MIP59c, were able to block up to 90% of soluble FcalphaR binding to IgA-coated beads and 70-80% of neutrophil phagocytosis of IgA immune complexes (IC). MIP8a could also inhibit IgA IC-induced neutrophil lactoferrin release, while cross-linking of FcalphaR with MIP8a and anti-mouse IgG could elicit neutrophil lactoferrin release. However, IgA IC-induced lactoferrin release required both extracellular calcium and magnesium, whereas MIP8a-induced release did not require extracellular magnesium and only partially required extracellular calcium. In addition, the time course of IgA IC-induced lactoferrin release was slow. Lactoferrin was not detectable if the incubation time was less than 0.5 h. In contrast, MIP8a-induced lactoferrin release was fast. Lactoferrin could be detected within 5 min of incubation. Therefore, neutrophil lactoferrin release induced by IgA IC differed from that induced by cross-linking of FcalphaR with MIP8a.

Animals↗

PubMed2000

Purification, characterization and structural analysis of an abundant beta-1,3-glucanase from banana fruit.

An abundant, catalytically active beta-1,3-endoglucanase (EC 3.2.1. 39) has been isolated from the pulp of ripe bananas. Biochemical analysis of the purified protein, molecular modelling, and molecular cloning of the corresponding gene indicate that this banana enzyme closely resembles previously characterized plant beta-glucanases with respect to its amino-acid sequence, structure and biological activity. The results described in this paper demonstrate both the occurrence of an abundant active beta-1,3-endoglucanases in fruits and also readdress the question of the possible involvement of these enzymes in the ripening and/or softening process.

Amino Acid Sequence↗

PubMed2000

A novel transmembrane serine/threonine protein kinase gene from a rifamycin SV-producing amycolatopsis mediterranei U32.

Genomic DNA sequencing in the vicinity of methylmalonyl-CoA mutase gene (mutAB) from a rifamycin SV-producing Amycolatopsis mediterranei U32 allowed us to clone, sequence, and identify a gene encoding a novel serine/threonine protein kinase (amk). The sequence contains a complete ORF of 1821 base pairs encoding a predicted protein of 606 amino acids in length. The N-terminal domain of the protein shows significant homology to the catalytic domain of other protein kinases from both prokaryotic and eukaryotic sources. It also contains all the structural features that are highly conserved in active protein kinases, including the Gly-X-Gly-X-X-Gly motif of ATP-binding and the essential amino acids known to be important for the recognition of the correct hydroxyamino acid in serine/threonine protein kinase. This protein kinase gene was expressed in Escherichia coli and was shown to have the ability of autophosphorylation. The autophosphorylated site was found to be the threonine at position 164 by labeled phosphoamino acid analysis and site-directed mutagenesis. The C-terminal half of protein kinase was found to contain strong transmembrane structures by PhoA fusion protein analysis, suggesting that Amk protein kinase is a transmembrane protein. A Southern hybridization experiment showed that this type of protein kinase is distributed ubiquitously and might play significant physiological roles in the various species of streptomycetes. However, overexpression of amk gene in Streptomyces cinnamonensis showed no effect on methylmalonyl-CoA mutase activity, monensin production and the hyphae morphology. Although its biological role is still unknown, Amk protein kinase is the first transmembrane serine/threonine protein kinase described for genus Amycolatopsis.

Actinomycetales↗

PubMed2000

Early postnatal maturation of GABAA-mediated inhibition in the brainstem respiratory rhythm-generating network of the mouse.

It is well established that GABAA-mediated postsynaptic potentials are excitatory in many brain regions during embryonic and early postnatal life. The pre-Bötzinger complex (PBC) in the brainstem is an essential component of the respiratory rhythm-generating network, where GABAA-mediated inhibition plays a critical role in generating a stable respiratory rhythm in adult animals. In the present study, using the perforated patch technique, we investigated the maturation of GABAA receptor-mediated effects on rhythmically active PBC neurons and on the motor output in slice preparations from P0-15 neonatal mice. The reversal potential of GABAA receptor-mediated current (EGABA-A) switched from depolarizing to hyperpolarizing within the first postnatal week. EGABA-A was -13.7 +/- 9.8 mV at P0, then it changed to -44.8 +/- 7.0 mV at P2 and -71.5 +/- 6.8 mV at P4. Perfusion of bicarbonate-free saline has no detectable influence on EGABA-A, indicating that a lack of Cl- extrusion during P0-3 is mainly responsible for early GABAA-ergic excitation. At the network level, blockade of GABAA receptors with bicuculline did not significantly change the frequency of rhythmic bursts recorded from hypoglossal nerve roots before P3, whereas it increased the coefficient of variation. After P3, bicuculline increased burst frequency with little effect on the coefficient of variation. Thus, chloride-mediated inhibition, which appears in PBC neurons after P3, coincides with the appearance of GABAA-mediated modulation of the respiratory rhythm. GABAA receptor-activated inhibition may therefore be necessary for frequency modulation in the respiratory network beginning on the fourth postnatal day in the mouse brainstem.

Action Potentials↗

PubMed2000

Metabotropic glutamate receptors and blockade of glial Krebs cycle depress glycinergic synaptic currents of mouse hypoglossal motoneurons.

Metabotropic glutamate receptors are known to depress synaptic transmission by inhibiting transmitter release from presynaptic nerve terminals. This study reports the effects of presynaptic metabotropic glutamate receptor activation on inhibitory synaptic transmission in hypoglossal motoneurons in brainstem slice preparations of neonatal mice. Whole-cell patch-clamp recordings were performed on hypoglossal motoneurons of 2-6-day-old mice. Monosynaptic glycinergic currents were elicited by electrical stimulation of the nucleus of Roller. Application of the specific metabotropic glutamate receptor agonists (+/-)-1-aminocyclopentane-trans-1,3,dicarboxylic acid (t-ACPD), (2S, 2'R,3'R)-2-(2',3'-dicarboxylcyclopropyl)-glycine (DCG-IV) or L-2-amino-4-phosphonobutyric acid (L-AP4) depressed stimulus-evoked glycinergic inhibitory postsynaptic currents (IPSCs) by an average of 39.5, 59.4 and 39.2%, respectively. In the presence of t-ACPD, glycinergic miniature IPSCs were reduced in frequency but not in amplitude, which is indicative of a presynaptic mechanism. A similar reduction of IPSC amplitude was observed in the presence of elevated extracellular glutamate or during application of D, L-threo-hydroxyaspartate (THA), a blocker of glutamate transport, respectively. The data suggest that uptake of glutamate, which is predominately carried out by glial cells, can prevent spill-over of glutamate and activation of metabotropic glutamate receptors. A reduction of IPSCs was also observed following application of monofluoroacetic acid, a substance acting specifically on glial cells. Our results suggest that glial regulation of extracellular glutamate uptake can prevent spill-over of glutamate, and glutamatergic depression of glycinergic inhibition in hypoglossal motoneurons.

Animals↗

PubMed2000

Metabolic coupling between glia and neurons is necessary for maintaining respiratory activity in transverse medullary slices of neonatal mouse.

The respiratory rhythm is generated and regulated by a neuronal network within the lower brainstem. While the neuronal mechanisms of rhythm generation have been extensively investigated, the contribution of glial cells remains to be determined. Here we report the effect of specific blockade of the glial Krebs cycle and glutamine synthetase on the neuronal activity of the respiratory network. Application of 5 mM fluoroacetate, which selectively blocks the glial Krebs cycle, suppressed rhythmic respiratory burst activity. Substitution of either the Krebs cycle substrate isocitrate (3 mM) or glutamine (3 mM) restored rhythmic network activity. Blockade of glutamine synthetase by methionine sulfoximine (0.5 mM) suppressed rhythmic burst activity as well. Resubstitution of glutamine (3 mM) was able to restore rhythmic activity in the presence of methionine sulfoximine. This data demonstrates that the glutamate-glutamine cycle in astrocytes and their supply of glutamine to neuronal glutamatergic terminals is essential for the rhythm generation in the respiratory centre.

Animals↗

PubMed2000

Association of a promoter polymorphism of tumor necrosis factor-alpha with subacute cutaneous lupus erythematosus and distinct photoregulation of transcription.

Ultraviolet irradiation stimulates keratinocytes and dermal fibroblasts to release cytokines involved in apoptosis and immunomodulation, such as tumor necrosis factor-alpha and interleukin-1alpha. Recent work has associated the -308A polymorphism of the human tumor necrosis factor-alpha promoter with systemic lupus erythematosus and adverse outcomes in several infectious diseases. To explore the role of this polymorphism in ultraviolet-induced disease, we used two approaches. First, we examined its prevalence in individuals with different ultraviolet sensitivity. Compared with healthy controls, there was a substantially increased prevalence of -308A in subacute cutaneous lupus erythematosus, an extremely photosensitive form of cutaneous lupus erythematosus, but not in discoid lupus erythematosus, a less photosensitive form. Next, to examine molecular regulation by tumor necrosis factor -308A, cultured 3T3 fibroblasts were transiently transfected with chloramphenicol acetyl transferase reporter constructs under the control of either -308A or the wild-type -308G promoter. Without added interleukin-1alpha the two constructs produced similar baseline chloramphenicol acetyl transferase activity and similar responses to ultraviolet. The responses to interleukin-1alpha, a photoinduced cytokine, were markedly different: interleukin-1alpha without ultraviolet produced a 15-fold increase in chloramphenicol acetyl transferase transcription from the -308A construct without affecting the wild-type -308G. Interleukin-1alpha plus ultraviolet B caused a remarkable 300-fold increase in -308A chloramphenicol acetyl transferase transcription over baseline, while increasing the wild type to <15% of this level. These results indicate a clear difference between the two promoters, including a striking synergy between ultraviolet B and added interleukin-1alpha in the induction of transcription by the tumor necrosis factor-alpha -308A promoter. Overall, our findings indicate a strong linkage between the -308A polymorphism and subacute systemic lupus erythematosus, which is likely to directly contribute to the photosensitivity of these patients.

Chloramphenicol O-Acetyltransferase↗

PubMed2000

Adenovirus-mediated gene transfer of human interleukin 10 ameliorates reperfusion injury of rat lung isografts.

OBJECTIVE: The objective of this study was to examine the feasibility of human interleukin 10 gene transfer into rat lung isografts and to investigate the effect of gene transfer on subsequent ischemia-reperfusion injury. METHODS: Male F344 rats were divided into 4 groups and underwent left lung isotransplantation. Twenty-four hours before harvest, 5 x 10E9 pfu (group I, n = 6) or 1 x 10E10 pfu (group II, n = 7) of AdRSVhIL-10 was intravenously administered to donor rats. In group I-C (n = 6) and group II-C (n = 6), serving as controls, 5 x 10E9 pfu and 1 x 10E10 pfu of AdCMVLacZ were administered, respectively. Grafts were preserved for 18 hours at 4 degrees C before implantation and assessed 24 hours after reperfusion. Transgene expression of human interleukin 10 was assessed by both reverse transcriptase-polymerase chain reaction and immunohistochemistry. Graft inducible nitric oxide synthase, tumor necrosis factor alpha, intercellular adhesion molecule-1, growth-regulated gene product/cytokine-induced neutrophil chemoattractant-1, and monocyte chemotactic protein-1 mRNA expression were assessed by reverse transcriptase-polymerase chain reaction. Isograft gas exchange, exhaled nitric oxide, and myeloperoxidase activity were also analyzed. RESULTS: Dose-dependent transgene expression was detected by reverse transcriptase-polymerase chain reaction and immunohistochemistry. Arterial PO (2) in groups I (164.72 +/- 85.3 mm Hg) and II (153.19 +/- 113 mm Hg) was significantly higher than in groups I-C (82.37 +/- 19.1 mm Hg) and II-C (77.95 +/- 33.4 mm Hg) (P =.022 and P =.031, respectively). Arterial PCO (2) in group I (33.40 +/- 6.80 mm Hg) was significantly lower than in group I-C (51.23 +/- 11.9 mm Hg) (P =.0096). Myeloperoxidase activity in group II (0.083 +/- 0.031 DeltaOD. min(-1). mg(-1)) was significantly lower than in group II-C (0.117 +/- 0.028 DeltaOD. min(-1). mg(-1)) (P =.044). The inducible nitric oxide synthase mRNA expression in group II (0.627 +/- 0.28) was significantly lower than in group II-C (1.125 +/- 0.63) (P =. 039). CONCLUSION: Adenovirus-mediated human interleukin 10 gene transfer in vivo into lung isografts ameliorates subsequent ischemia-reperfusion injury. This results in improved graft gas exchange, reduced neutrophil sequestration, and down-regulation of graft inducible nitric oxide synthase mRNA expression.

Adenoviridae↗

PubMed2000

Synthetic retinoids improve survival in rodent model of endotoxic shock.

OBJECTIVE: To investigate the effect of synthetic retinoids on septic shock induced by lipopolysaccharide (LPS) in rats. DESIGN: Randomised study. SETTINGS: University hospital laboratory, Sweden. ANIMALS AND INTERVENTIONS: 31 male Sprague Dawley rats randomised into four groups: controls, given vehicle alone (n = 6), LPS 6 mg/kg body weight alone (n = 12), and LPS 6 mg/kg but pretreated with the retinoic acid receptor-alpha (RAR-alpha) agonists CD336 (n = 6) and CD2081 (n = 7). MAIN OUTCOME MEASURES: Arterial blood pressure and heart rate measured hourly for four hours; mortality. RESULTS: LPS caused a pronounced fall in blood pressure within one hour of injection in all groups of rats. Of the 12 rats given LPS but not RAR-alpha agonists, 6 died before the end of the experiment. By contrast, all animal given either CD336 or CD2081 survived. The significantly improved survival was found despite no significant improvements in either mean arterial pressure or heart rate. CONCLUSION: Pretreatment with selective synthetic RAR-alpha agonists improves survival after LPS-induced septic shock in rats. These agents may have therapeutic potential in the treatment of septic shock in humans.

Animals↗

PubMed2000

Randomized comparative trial in parous women of the frameless GyneFix and the TCu380A intrauterine devices: long-term experience in a Chinese family planning clinic.

OBJECTIVE: To compare the clinical performance of two intrauterine devices (the frameless GyneFix intrauterine device (IUD) and the TCu380A IUD) during long-term use. STUDY DESIGN: This was a randomized comparative study. A total of 157 insertions of the GyneFix IUD were compared with 156 insertions of the TCu380A IUD in the Tianjin Municipal Institute for Family Planning, China. Only parous women were included in the study. Insertions were conducted by the first three authors. The trial extended over a 9-year period, with over 10,000 woman-months of experience. RESULTS: The study showed that both devices are highly efficacious. No pregnancies occurred with the GyneFix IUD (cumulative pregnancy rate 0.0), compared to one pregnancy with the TCu380A IUD (cumulative pregnancy rate 0.64). The cumulative expulsion rate with the GyneFix IUD was 1.91 (three expulsions occurred, two of which were during the first 6 months), compared to a cumulative expulsion rate of 5.13 (eight expulsions) with the TCu380A (p = 0.1112). The total use-related discontinuation rate (terminations were mainly due to bleeding disturbances) was significantly lower (p = 0.0051) with the GyneFix IUD (4.46) than with the TCu380A IUD (14.10) and resulted in a higher rate of continuation with the GyneFix IUD compared to the TCu380A IUD (92.36 versus 83.97). Neither perforations nor cases of pelvic inflammatory disease were encountered with either device in this study, demonstrating the safety of the anchoring system. CONCLUSION: The results of the present clinical trial are in agreement with the findings of other multicenter, randomized, comparative, clinical trials that have investigated these two IUDs in China, as well as with the findings of other large-scale international studies conducted with the frameless IUD.

Adult↗

PubMed2000

Long-chain polyunsaturated fatty acids in children with attention-deficit hyperactivity disorder.

Attention-deficit hyperactivity disorder (ADHD) is the diagnosis used to describe children who are inattentive, impulsive, and hyperactive. ADHD is a widespread condition that is of public health concern. In most children with ADHD the cause is unknown, but is thought to be biological and multifactorial. Several previous studies indicated that some physical symptoms reported in ADHD are similar to symptoms observed in essential fatty acid (EFA) deficiency in animals and humans deprived of EFAs. We reported previously that a subgroup of ADHD subjects reporting many symptoms indicative of EFA deficiency (L-ADHD) had significantly lower proportions of plasma arachidonic acid and docosahexaenoic acid than did ADHD subjects with few such symptoms or control subjects. In another study using contrast analysis of the plasma polar lipid data, subjects with lower compositions of total n-3 fatty acids had significantly more behavioral problems, temper tantrums, and learning, health, and sleep problems than did those with high proportions of n-3 fatty acids. The reasons for the lower proportions of long-chain polyunsaturated fatty acids (LCPUFAs) in these children are not clear; however, factors involving fatty acid intake, conversion of EFAs to LCPUFA products, and enhanced metabolism are discussed. The relation between LCPUFA status and the behavior problems that the children exhibited is also unclear. We are currently testing this relation in a double-blind, placebo-controlled intervention in a population of children with clinically diagnosed ADHD who exhibit symptoms of EFA deficiency.

Animals↗

PubMed2000

Scanning electron microscopic changes in the morphology of rabbit pulmonary tissue biopsied following ischemia and reperfusion: a window of opportunity?

Reperfusion is known to cause tissue damage in ischemic pulmonary tissue. We investigated the time frame of this occurrence by examining electron microscopic changes in lung tissue. Isolated, perfused, and ventilated rabbit lungs (and heart) were placed en bloc in a 37 degrees C chamber and perfused through the pulmonary artery at 15 mm Hg pressure with oxygenated Krebs-Henseleit buffer, pH 7.4, 70 ml min(-1), for 20 min and the pulmonary pump and ventilator were stopped. The resultant ischemic state was maintained for 2 h, and reperfusion resumed with the same buffer. The lungs of four groups of rabbits (n = 5 per group) were each subjected to 30 min, 1, 2, and 4 h of reperfusion respectively. Upon completion, lungs were biopsied for scanning electron microscopy. Ischemic damage including the loss of lung architecture, and edema were seen. Reperfusion restored some of the tissue anatomy and the return to normalcy increased up to 1 h of reperfusion after which the damage increased with time. Results suggest that damage due to ischemia alone may be reversible. Initial recovery is due to the re-establishment of circulation. However, with time, the damage seen may be due to free radicals and with 4 h of reperfusion, cell death may have occurred.

Animals↗

PubMed2000

Inflammatory activation of human brain endothelial cells by hypoxic astrocytes in vitro is mediated by IL-1beta.

Leukocyte infiltration into the brain contributes to the development of ischemic brain damage and is mediated by endothelial/leukocyte adhesion molecules, cytokines, and chemokines released by ischemic brain cells. In this study, we provide evidence that human astrocytes (FHAs) subjected to in vitro hypoxia produce proinflammatory mediator(s) capable of up-regulating inflammatory genes, including intercellular adhesion molecule-1, interleukin (IL)-1beta, tumor necrosis factor-alpha, IL-8, and monocyte chemotactic protein-1 (MCP-1) in human cerebromicrovascular endothelial cells (HCECs). FHAS were exposed to hypoxia in an anaerobic chamber for 4 hours, followed by reoxygenation for 24 hours. Astrocyte-conditioned media (ACM) collected from normoxic FHAS or FHAS subjected to hypoxia/reoxygenation were applied to HCEC cultures for 4 to 24 hours. Semiquantitative reverse transcription-polymerase chain reaction, immunocytochemistry, and enzyme-linked immunosorbent assay demonstrated up-regulation of intercellular adhesion molecule-1 in HCECs exposed to hypoxic ACM. A pronounced elevation in cytokine IL-1beta and tumor necrosis factor-alpha, and chemokine IL-8 and MCP-1 mRNA, accompanied by increased release of immunoreactive cytokines and chemokines into cell media was observed in HCECs exposed to hypoxic ACM. Hypoxia/reoxygenation induced a transient (4 to 18 hours of reoxygenation) up-regulation of IL-1beta mRNA in FHAS and a two- to threefold increase in IL-1beta levels secreted into ACM. Pretreatment of FHAS with 10 micromol/L dexamethasone inhibited both hypoxia-induced expression/secretion of IL-1beta and the ability of hypoxic ACM to induce inflammatory phenotype in HCECs. The ability of hypoxic ACM to up-regulate inflammatory genes in HCECs was inhibited in the presence of IL-1 receptor antagonist (IL-1Ra) and by pretreating ACM with the blocking anti-IL-1beta antibody. These findings strongly implicate IL-1beta secreted by hypoxic astrocytes in triggering inflammatory activation of HCECs and thereby influencing inflammatory responses at the site of the blood-brain barrier.

Antisense Elements (Genetics)↗