Partial agonist activity of 11-cis-retinal in rhodopsin mutants

Rhodopsin, the photoreceptor molecule of the vertebrate rod cell, is a G protein-coupled receptor. Rhodopsin consists of the opsin apoprotein and its 11-cis-retinal chromophore, which is covalently bound to a specific lysine residue by a stable protonated Schiff base linkage. Rhodopsin activation occurs when light causes photoisomerization of the 11-cis chromophore to its all-trans form. The all-trans chromophore is the receptor agonist. The 11-cis-retinylidene chromophore is analogous pharmacologically to a potent inverse agonist of the receptor. We report here that replacement of a highly conserved glycine residue (Gly121) causes 11-cis-retinal to become a pharmacologic partial agonist. Although the mutant apoproteins do not display constitutive activity, they are active in the dark when bound to an 11-cis-retinylidene chromophore, or to a "locked" chromophore analogue, Ret-7. The degree of partial agonism is directly related to the size of the amino acid replacement at position 121, and it can be reversed by a specific second-site replacement of Phe261. Thus, mutation of Gly121 in rhodopsin causes 11-cis-retinal to act as a partial agonist rather than an inverse agonist, allowing the mutant pigment to activate transducin in the dark.

[Dynamic observations on pulmonary function in retired miners exposed to nickel dust]

Pulmonary ventilation functions were determined dynamically in 34 retired miners exposed to nickel dust and 28 non-exposed ones in 1981, 1988 and 1995, respectively to study their damage and change patterns. Results showed that mean forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were lower in retired miners than those in controls at any time of determination. FVC and FEV1 lowered with time both in retired or control groups, with statistical significance. However, decrease of FVC and FEV1 in the retired was more than that in the controls whether during 1981 to 1988, or 1988 to 1995, or 1981 to and 1995. And, proportion of abnormal FVC and FEV1 increased more and extent of their abnormality was more severe in retired group than those in controls.

Modulation of soluble and membrane-bound TNF-induced phenotypic and functional changes of human brain microvascular endothelial cells by recombinant TNF binding protein I

In this study, the effects of TNF binding protein I (TBP I) on TNF-induced changes of human brain microvascular endothelial cells (MVEC) were investigated. TBP I completely abolished TNF-induced IL-6 production and E-selectin induction, while it partially inhibited TNF-induced IL-8 production and up-regulation of ICAM-1 and VCAM-1. Moreover, TBP I significantly inhibited TNF-induced cytotoxicity and leukocyte adherence on human brain MVEC. The inhibitory activity of TBP I for TNF was dose-dependent and related to the time of administration after TNF stimulation. In addition, TBP I inhibited membrane-bound TNF induced activation of human brain MVEC, but the concentration required was about 10-fold higher than that for soluble TNF. These results indicate a therapeutic potential for TBP I in diseases of the central nervous system associated with TNF overproduction.

[Matching study of lung function and respiratory symptoms in ex-dust exposure miners]

The lung function tests and respiratory symptom investigations were carried out on 156 pairs of ex-dust exposure miners and control workers according to match designing method. The matching was based on age, height, weight and smoking habit. The result showed that ex-dust exposure miners had higher frequency of abnormal lung function than that of control workers. Compared with control workers, the prevalence of respiratory symptoms and the incidence of chronic bronchitis were higher in ex-dust exposure miners.

Generation of a mouse tumor necrosis factor mutant with antiperitonitis and desensitization activities comparable to those of the wild type but with reduced systemic toxicity

In this study, we investigated whether the recently identified lectin-like domain of tumor necrosis factor (TNF) is implicated in its biological activities on mammalian cells. To this end, a mouse TNF (mTNF) triple mutant, T104A-E106A-E109A mTNF (referred to hereafter as triple mTNF), lacking the lectin-like affinity of mTNF for specific oligosaccharides, was compared with the wild-type molecule for various TNF effects in vitro and in vivo. The triple mTNF displayed a 50-fold-reduced TNF receptor 2 (TNFR2)-mediated bioactivity but only a 5-fold-reduced TNFR1-mediated bioactivity in vitro. The specific activity of the triple mutant on L929 fibrosarcoma cells was slightly reduced compared with that of the wild type. We subsequently assessed the systemic toxicity of triple versus wild-type mTNF, since TNFR2 is partially implicated in this activity. The triple mTNF had a significantly reduced toxicity compared with that of wild-type mTNF in vivo. Moreover, we compared the effects of the triple and the wild-type mTNFs in TNFR1-mediated phenomena, such as (i) induction of tolerance towards a lethal mTNF dose and (ii) protective activity in cecal ligation and puncture-induced septic peritonitis. No significant differences between the mutant and wild-type forms were observed. In conclusion, these results indicate that triple mTNF, lacking TNF's lectin-like binding capacity, has reduced systemic toxicity but retains the tolerance-inducing and peritonitis-protective activities of wild-type mTNF.

[Effect of sodium iron chlorophyllin (SIC) on CFU-E and CFU-GM yields of normal and anemic animal models]

OBJECTIVE

To observe the effect of sodium iron chlorophyllin (SIC) on hematopoiesis and its therapeutic efficacy in anemic mice.

METHODS

The effects of SIC on CFU-E and CFU-GM yields of normal and anemic animal models were studied.

RESULTS AND CONCLUSIONS

(1) SIC significantly enhanced the CFU-E and CFU-GM yields of mouse bone marrow. (2) SIC also increased the percentage of reticulocyte in mouse. (3) In hemolytic anemia mice induced by i.p. N-acetphenylhydrazine, SIC markedly prevented the decrease of RBC and Hb. (4) In hemorrhagic anemia rats induced by bleedletting, SIC accelerated the normalization of RBC, Hb and elevated the serum iron level and transferrin saturation.

TNF receptors in the microvascular pathology of acute respiratory distress syndrome and cerebral malaria

The microvascular endothelial cell (MVEC) is a major target of inflammatory cytokines overproduced in conditions such as sepsis and infectious diseases. We addressed the direct and indirect effects of tumor necrosis factor (TNF) on endothelial cells that can be relevant for the pathogenesis of septic shock, with particular attention to the acute respiratory distress syndrome (ARDS) and to cerebral malaria (CM). To identify functional and phenotypical changes occurring in MVEC during sepsis, we isolated these cells from the lungs of patients who died of ARDS. The constitutive expression of ICAM-1 and, to a lesser extent, VCAM-1, CD14, and TNFR2 were significantly increased on MVEC isolated from ARDS patients compared with control MVEC, whereas ELAM-1 and TNFR1 were not increased. We found that lung MVEC from ARDS patients present a procoagulant profile and a higher production capacity of interleukin-6 (IL-6) and IL-8 when compared with those from controls. As in pulmonary MVEC derived from ARDS patients, the only TNFR type found up-regulated in brain microvessels during CM was TNFR2. This increase in TNFR2 expression only occurred in CM-susceptible mice at the onset of the neurological syndrome. We therefore investigated the role of TNFR2 in the development of this brain pathology by comparing the incidence of CM in wild-type and TNF receptor knock-out mice. Unexpectedly, the genetic deficiency in TNFR2, but not in TNFR1, conferred protection against CM and its associated mortality. No ICAM-1 up-regulation was detected in the brain of Tnfr2 knockout mice, indicating a close correlation between protection against CM-associated brain damage, absence of TNFR2, and absence of ICAM-1 up-regulation in the brain. Our results in ARDS and CM indicate a specific up-regulation of TNFR2, but not of TNFR1, on lung and brain MVEC, respectively. This increased expression leads to a reduced sensitivity toward TNFR1-mediated phenomena, such as the sensitized TNF cytolytic activity on lung MVEC. In contrast, the sensitivity toward TNFR2-mediated effects, such as ICAM-1 induction by membrane-bound TNF, is increased on brain and lung MVEC expressing increased levels of TNFR2. Therefore, the ICAM-1-inducing effect, rather than the direct cytotoxicity of inflammatory cytokines, such as TNF, appears to be crucial in ARDS and CM-induced endothelial damage, and TNFR2 seems to play an important role in this activity in vivo.

Haemostatic properties of human pulmonary and cerebral microvascular endothelial cells

Little is known on the haemostatic profiles of human microvascular endothelial cells (MVEC) from different tissues. In addition it is not known whether MVEC from patients display the same haemostatic pattern as MVEC coming from healthy controls. To address these questions MVEC from human lung and brain were isolated and stimulated with tumour necrosis factor alpha (TNF) and E. coli lipopolysaccharide (LPS) for 24 h. The level and the kinetics of procoagulant activity (PCA) and thrombomodulin (TM) expression were found to be different depending on the tissue of origin and on the agonist used. In particular, the inducible PCA was higher in lung than in brain MVEC, an observation that may be related to the frequency of lung involvement in septic shock. Differences were also observed for tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) with MVEC supernatants or cell lysates. These variables were then measured in lung MVEC purified from patients with acute respiratory distress syndrome (ARDS) and compared to controls. Cells from ARDS patients constitutively expressed more PCA and PAI-1 than controls. The fibrinolytic potential, expressed as t-PA/PAI-1 ratio, was lower in ARDS than in lung MVEC. It is concluded that MVEC display different haemostatic features depending on the tissue they come from and that lung MVEC from ARDS patients present a procoagulant profile when compared with those from controls.

Brain microvascular endothelial cells and leukocytes derived from patients with multiple sclerosis exhibit increased adhesion capacity

The adhesion properties of brain microvascular endothelial cells (MVEC) and leukocytes derived from patients with multiple sclerosis (MS) were investigated. Leukocytes and brain MVEC from MS patients exhibited significantly higher adhesion capacity than the same cells isolated from normal donors. Flow cytometry showed that MS-derived brain MVEC constitutively expressed higher levels of ICAM-1 and contained an increased proportion of MHC class II positive cells than normal brain MVEC. In contrast, no difference was seen for vascular cell adhesion molecule-1 and endothelial cell leukocyte adhesion molecule-1. Circulating leukocytes from MS patients expressed higher levels of LFA-1, a ligand of intercellular adhesion molecule-1 (ICAM-1), than did normal leukocytes. The data presented here suggest that the ICAM-1/LFA-1 interaction may determine cytoadherence of leukocytes to brain MVEC in MS.

Direct cell/cell contact with stimulated T lymphocytes induces the expression of cell adhesion molecules and cytokines by human brain microvascular endothelial cells

Upon inflammation, stimulated, but not resting T lymphocytes cross the blood-brain barrier and migrate into the central nervous system. This study shows that direct contact between stimulated T lymphocytes and human brain microvascular endothelial cells (HB-MVEC) induces phenotypic and functional changes on the latter cells. Plasma membranes isolated from stimulated T lymphocytes (S-PM) up-regulated the expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin on isolated HB-MVEC. In addition, HB-MVEC activated by S-PM secreted interleukin (IL)-6 and IL-8. The levels of ICAM-1, E-selectin, IL-6, and IL-8 expressed in S-PM-activated HB-MVEC were similar to those observed with 1000 U/ml tumor necrosis factor (TNF). In contrast, VCAM-1 expression was 15% of that induced by TNF. Inhibitors of TNF diminished (< or = 45%), but did not abolish the expression of cell adhesion molecules and IL-6 induced by S-PM, IL-8 production being insignificantly affected (< or = 10%). This suggests that membrane-associated TNF was partially involved in HB-MVEC activation. The present study demonstrates that stimulated T lymphocytes are able to activate HB-MVEC upon direct cell contact. This novel mechanism of inducing the expression of cell adhesion molecules may prompt the initial adhesion of stimulated T lymphocytes to brain endothelium.

Experience of varicella vaccination in acute lymphoplastic leukaemia

Varicella is a common benign childhood illness. Rarely, serious complications arise. Immunocompromised patients usually suffer a more serious form of the illness. It is therefore prudent to prevent the infection in this group of patients. Varicella vaccination has been proven by several workers to be effective in both healthy children and adults as well as in leukaemic children. As the vaccine had not been licensed for sale in Singapore, we could only import 10 doses of the vaccine under special license. This was given to 8 leukaemic children. Of this, 5 seroconverted after the first dose. Two patients had the benefit of a repeat vaccination 3 months later. Both subsequently seroconverted. Two of the patients died from a relapse of the illness, a year and 2 years after the vaccination. None of the patients developed any side effects of fever and pain or varicella or zoster after the immunisation even though there was close contact with chicken pox. Although the study sample was small, it appeared that the vaccine was safe and efficacious in leukaemic children, especially after a 2-dose injection.

Immunodeficiency and chronic myelogenous leukemia-like syndrome in mice with a targeted mutation of the ICSBP gene

Interferon consensus sequence binding protein (ICSBP) is a transcription factor of the interferon (IFN) regulatory factor (IRF) family. Mice with a null mutation of ICSBP exhibit two prominent phenotypes related to previously described activities of the IRF family. The first is enhanced susceptibility to virus infections associated with impaired production of IFN(gamma). The second is deregulated hematopoiesis in both ICSBP-/- and ICSBP+/- mice that manifests as a syndrome similar to human chronic myelogenous leukemia. The chronic period of the disease progresses to a fatal blast crisis characterized by a clonal expansion of undifferentiated cells. Normal mice injected with cells from mice in blast crisis developed acute leukemia within 6 weeks of transfer. These results suggest a novel role for ICSBP in regulating the proliferation and differentiation of hematopoietic progenitor cells.

Adenovirus-mediated gene transfer into tendon and tendon sheath

In this study, we successfully transferred the Escherichia coli beta-galactosidase gene. LacZ, into the chicken tendon and tendon sheath by a recombinant adenovirus. The recombinant adenovirus Adv-beta gal that carried the E. coli LacZ gene was constructed by homologous recombination in 293 cells (human transformed embryonic kidney) between the expressing vector and the ClaI large fragment of adenovirus 5 genome. Each chicken received a 10 microliters injection containing 10(5) plaque-forming units of recombinant virus Adv-beta gal. into the tendon sheath of the long toe Samples of tendon and tendon sheath were harvested at 3.30, and 75 days after the injection. The LacZ gene transfer was detected for its coding product beta-galactosidase by staining with X-gal solution. The results showed that all tendon and tendon sheath samples from the three harvest times stained positive (blue). The tendon sheath samples were more extensively stained; staining of the tendon was limited to the epitenon layer. These data suggest that a functional exogenous gene can potentially be transferred into the tendon and tendon sheath by similar techniques; such techniques may be used to improve healing and reduce adhesion formation.

Lungs in thalassaemia major patients receiving regular transfusion

Progressive tissue iron deposition from multiple blood transfusions is common in beta-thalassaemia and pulmonary iron deposition may result in parenchymal damage. The objectives of this study were to: 1) determine the predominant pulmonary dysfunction in patients with thalassaemia major; and 2) demonstrate that parenchymal disease, if present, is at the level of the alveolocapillary membrane. Fourteen thalassaemia major patients (13 nonsmokers) receiving regular blood transfusion and without any history of chronic respiratory disease were recruited. Pulmonary function tests and echocardiography were performed before the scheduled transfusions. Three patients with the most restricted lung function were selected for high resolution computerized tomography (CT) of the lungs. One patient had an obstructive pattern with a forced expiratory volume in one second as percentage of forced vital capacity (FEV1/FVC) of 71%. Four patients demonstrated a restrictive pattern, as defined by total lung capacity (TLC) less than 80% predicted with normal FEV1/FVC%. Twelve patients had pulmonary transfer factors for carbon monoxide (TL,CO) below 80% pred, even after correction for the anaemia, indicating parenchymal disease. Eight of these 12 patients had alveolocapillary membrane defect, as demonstrated by a gas transfer factor of the pulmonary membrane (Tm) less than 80% pred. Mean resting arterial oxygen saturation was 95 +/- 2 (range 92-98) %. Eleven patients had oxygen desaturation of 5% or more during exercise on a bicycle ergometer, consistent with interstitial lung disease. There was no clinical or echocardiographic evidence of heart failure. Percentage predicted TLC was inversely correlated with age (r = -0.547; p = 0.043). Both percentage predicted TLC and TL,CO were not correlated with iron burden or desferoxamine ratio. High resolution CT in the three selected patients showed no evidence of pulmonary fibrosis. We conclude that thalassaemia major patients have a predominant restrictive lung dysfunction with pulmonary parenchymal disease and alveolocapillary membrane block. The restrictive and interstitial lung disease could not be accounted for by iron loading or pulmonary fibrosis in our patients.

New synthetic sulfated oligosaccharides prolong survival of cardiac xenografts by inhibiting release of heparan sulfate from endothelial cells

Binding of recipient natural antibodies to the endothelium of the graft, complement activation, endothelial cell activation, and microvascular thrombosis are major events in the hyperacute rejection of organ xenografts. The aim of this study was to investigate the effects of two new synthetic sulfated oligosaccharides (A and B) on the survival of discordant cardiac xenografts in the guinea pig-to-rat model. In untreated recipients, hyperacute rejection occurred in 5 min (median; range, 4-6 min) and immunohistological analysis of all the grafts revealed deposition of IgM and C3 along the endothelium. Administration of oligosaccharides A and B prior to revascularization prolonged the survival of xenografts in a dose-dependent manner, up to 113 min (median; range, 42-145 min) and 86 min (median; range, 35-108 min), respectively, when doses of 20 mg/kg were used. There were no bleeding complications. Histological examination of the rejected grafts showed a picture of hyperacute rejection, with no difference in IgM and C3 deposition as compared with the untreated animals. In cell culture experiments, the release of heparan sulfate from guinea pig cardiac endothelial cells induced by rat serum was inhibited by both saccharides in a dose-dependent manner. The results indicate that these new synthetic sulfated oligosaccharides are effective for prolongation of discordant xenograft survival, possibly by interfering with endothelial cell activation. Such substances may be of value in other xenotransplant combinations.

Role of phosphorolytic cleavage in cellobiose and cellodextrin metabolism by the ruminal bacterium Prevotella ruminicola

In bacteria, cellobiose and cellodextrins are usually degraded by either hydrolytic or phosphorolytic cleavage. Prevotella ruminicola B(1)4 is a noncellulolytic ruminal bacterium which has the ability to utilize the products of cellulose degradation. In this organism, cellobiose hydrolytic cleavage activity was threefold greater than phosphorolytic cleavage activity (113 versus 34 nmol/min/mg of protein), as measured by an enzymatic assay. Cellobiose phosphorylase activity (measured as the release of P(i)) was found in cellobiose-, mannose-, xylose-, lactose-, and cellodextrin-grown cells (> 92 nmol of P(i)/min/mg of protein), but the activity was reduced by more than 74% for cells grown on fructose, L-arabinose, sucrose, maltose, or glucose. A small amount of cellodextrin phosphorylase activity (19 nmol/min/mg of protein) was also detected, and both phosphorylase activities were located in the cytoplasm. Degradation involving phosphorolytic cleavage conserves more metabolic energy than simple hydrolysis, and such degradation is consistent with substrate-limiting conditions such as those often found in the rumen.

Detection of PML-RAR alpha in patients with APL during follow-up period

OBJECTIVE

To evaluate the significance of PML-RAR alpha transcripts in patients with acute promyelocytic leukemia (APL) during remission period and to follow up the patients through monitoring aberrant gene expression.

PATIENTS AND METHODS

This study included 17 patients with APL (5 females and 12 males). Another 19 APL patients during relapse served as control. RNA extraction was obtained through the single-step method. By means of reverse transcriptase polymerase chain reaction (PCR), the PML-RAR alpha was detected in the sample mRNA.

RESULTS

Nine out of 10 patients with complete remission (CR) duration shorter than 3 years were positive. Four cases became negative and three remained positive among 7 cases in a long remission of over 3 years. The difference of the positive rate of PML-RAR alpha transcripts between the 2 groups was significant (P < 0.05). Four among 12 positive cases relapsed. No evidence of relapse was present in the 5 negative patients after 9.6 +/- 3.9-month follow-up. Further treatment was therefore given to the 4 positive patients whose treatment was already ceased at that time. By this management they were all in CR during the following 10-month observation.

CONCLUSIONS

RT-PCR detection for PML-RAR alpha transcripts was useful in monitoring MRD and guiding further treatment to obtain a long remission. Persistently positive transcripts were closely associated with the relapse.

[Production and characterization of sterigmatocystin]

Two strains of Aspergillus versicolor producing ST at 550.8 mg.kg-1 substrate and 1160.8 mg.kg-1 substrate were selected to inoculate 4 kg solid ST-producing media. After 35 days stationary incubation at 28 degrees C in the dark, 2271.6 mg of pale-yellow needle-shaped crystals were isolated and purified from the culture with a procedure applying column chromatography and recrystallization method. The crystal was proved to be sterigmatocystin by spectroanalysis and some physico-chemical analysis. The purity of the final material obtained were more that 99.9% as shown by HPLC and TLC detection. With this procedure, ST was obtained at about one tenth of its commercial cost.

[Determination of sterigmatocystin in cancerous tissues, blood and urine in patients with liver and stomach cancer]

Sterigmatocystin (ST) was determined with modified Southern-Western blot and indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) for 28 specimens of cancerous tissues, 13 of blood and 20 of urine in 14 patients with liver and stomach cancer. Results showed DNA-ST adduct was detected in 14 specimens of cancerous tissues and/or pericancerous tissues. ST values were higher in four of 13 patients (65-113 micrograms/kg), as compared only in one of 14 healthy persons (68 micrograms/kg). And, ST values all were very low in urine, with a maximum of 13 micrograms/kg.

Vesicular stomatitis virus infection induces a nuclear DNA-binding factor specific for the interferon-stimulated response element

Vesicular stomatitis virus (VSV) has a broad host range. It replicates in the cytoplasm and causes rapid cytopathic effects. We show that following VSV infection, a nuclear factor that binds to a select set of interferon-stimulated responsive elements (ISRE) is induced in many cell types. This factor, tentatively called VSV-induced binding protein (VIBP), was estimated to have an approximate molecular mass of 50 kDa and was distinct from known members of the interferon regulatory factor family, that are known to bind to the ISRE. Induction of VIBP required tyrosine kinase activity but did not require cellular transcription. Treatment of cells with cycloheximide, which inhibits translation, only partially inhibited induction of VIBP. However, type I interferons and staurosporine, both of which inhibit VSV transcription, inhibited VIBP induction. Moreover, a double-stranded RNA analog, poly(I)-poly(C) also induced a DNA-binding activity very similar to that of VIBP. These results indicate that a preexisting cellular protein is activated upon VSV infection and that this activation requires primary viral transcripts. The functional activity of VIBP was analyzed in cells stably transfected with a herpesvirus thymidine kinase-luciferase reporter gene that is under control of the ISRE. While activity of the control promoter without ISRE was strongly inhibited following VSV infection (as a result of virus-mediated transcriptional shutdown of the host cell), the inhibition was reversed by the ISRE-containing promoter, albeit partially, which suggests that VSV infection differentially affects transcription of host genes. Although VIBP was induced in all other cells tested, it was not induced in embryonal carcinoma cells after VSV infection, suggesting developmental regulation of VIBP inducibility.

[Preparation and identification of monoclonal antibody against sterigmatocystin]

Compound antigen, bovine serum albumin-sterigmatocystin (BSA-ST) or hemocyanin sterigmatocystin (H-ST) was prepared by converting ST to its hemiacetal group in ST and taking ST conjugated to BSA or H. Balb/c mice were immunized with BSA-ST, and then their spleen cells were isolated and fused with SP2/0 murine myeloma cells. A hybridoma cell strain that could stably secrete monoclonal antibody against ST (McAb-ST) was selected, and both of their ascites and serum were rich in McAb-ST induced by cells of this strain. McAb-ST was identified as Ig-Gi with a molecular weight of 168,000 kd (53,000 for heavy chain and 31,000 for light one), and with an affinity constant of H-ST reaction of 1.29 x 10(9) mol/L measured by indirect competitive enzyme-linked immunosorbent assay (IC-ELISA). Relative cross reaction of McAb-ST with ST analogues was less than 2%. The minimal 0.5 pg/25 microliters of ST can be detected with IC-ELISA using McAb-ST and ST simultaneously, with a linear range of 0.1-10 ng/ml.

Astrocyte response and transforming growth factor-beta localization in acute spinal cord injury

STUDY DESIGN

An experimental histologic and immunohistological investigation of acute spinal cord injury was performed in a rat model.

OBJECTIVE

This study determined (1) the immediate cellular and molecular responses within the spinal cord that result from a clinically relevant compression injury, (2) the acute astrocytic response to injury using the astrocyte specific GFAP antibody, and (3) the temporal pattern of cellular and extracellular localization of transforming growth factor-beta 1 (TGF-beta 1) within the spinal cord injury zone immediately after injury.

SUMMARY OF BACKGROUND DATA

Ultimate neurologic outcome from spinal cord injury results from both the primary mechanical trauma and a subsequent cascade of cellular and molecular events that are termed the secondary injury. Efforts aimed at improving neurologic outcome may depend on the manipulation of cellular and molecular mechanisms that are responsible for propagating this secondary injury cascade. Astrocytes and TGF-beta are two potentially key components of this secondary injury.

METHODS

Twenty-one Sprague-Dawley adult rats underwent open thoracic spinal cord injuries using the Allen weight-drop technique. Spinal cord specimens were harvested at 0, 1, 2, 4, 8, 24, and 72 hours after injury for histologic and immunohistochemical evaluation. Harvesting of injured and surrounding uninjured cord was performed before sectioning in sagittal and transverse planes. These paraffin-embedded sections were stained with polyclonal antibodies against glial fibrillary acidic protein (GFAP, an astrocytic cytoskeleton marker) and TGF-beta 1.

RESULTS

A complex astrocytic response to the spinal cord injury was found within 24 hours of injury. Both the geographic and temporal patterns of astrocyte localization suggest a role in the regulation of spinal cord injury propagation. High concentrations of extracellular TGF-beta were seen immediately after injury within the hematoma at the zone of impact. Subsequently, intracellular TGF-beta was seen in astrocytic nuclei and cytoplasm, intramedullary and extramedullary capillary endothelial cells, and in motor neurons.

CONCLUSIONS

The neurologic outcome in patients with SCI results in part from a secondary injury whose cellular and molecular mechanisms are poorly understood. This study suggests that both astrocytes and TGF-beta are involved in the regulation of spinal cord secondary injury. An improved understanding of their specific roles may result in novel treatments to improve the outcome from SCI.

The endoplasmic reticular heat shock protein gp96 is transcriptionally upregulated in interferon-treated cells

A cDNA clone complementary to an interferon (IFN)-induced mRNA approximately 3 kb in length was identified and sequenced revealing homology with the endoplasmic reticular heat shock protein/ATPase gp96. Both IFN-alpha and -gamma transcriptionally upregulate expression of this gene. gp96 transcripts, protein, and ATPase activity are shown to be enhanced as a result of IFN treatment in two human cell lines and this effect requires de novo protein synthesis. gp96 molecules have recently been implicated in the presentation of endogenous antigens. A number of the key elements in this pathway, the transporter proteins, the major histocompatibility complex (MHC)-linked units of the proteasomes and the MHC class I molecules are known to be IFN inducible. Our results show that yet another molecule suggested to play an accessory role in the endogenous presentation pathway is IFN inducible. Further, our studies represent the first demonstration of modulation of expression of a heat shock protein by a cytokine and identify a new enzymatic activity upregulated in IFN-treated cells.