The Escherichia coli RNA polymerase alpha subunit linker: length requirements for transcription activation at CRP-dependent promoters

The C-terminal domain of the Escherichia coli RNA polymerase alpha subunit (alphaCTD) plays a key role in transcription initiation at many activator-dependent promoters. This domain is connected to the N-terminal domain by an unstructured linker, which is proposed to confer a high degree of mobility on alphaCTD. To investigate the role of this linker in transcription activation we tested the effect of altering the linker length on promoters dependent on the cyclic AMP receptor protein (CRP). Short deletions within the alpha linker decrease CRP-dependent transcription at a Class I promoter while increasing the activity of a Class II promoter. Linker extension impairs CRP-dependent transcription from both promoters, with short extensions exerting a more marked effect on the Class II promoter. Activation at both classes of promoter was shown to remain dependent upon activating region 1 of CRP. These results show that the response to CRP of RNA polymerase containing linker-modified alpha subunits is class specific. These observations have important implications for the architecture of transcription initiation complexes at CRP-dependent promoters.

Evidence for apoptosis after intercerebral hemorrhage in rat striatum

The overall hypothesis that cell death after intracerebral hemorrhage is mediated in part by apoptotic mechanisms was tested. Intracerebral hemorrhage was induced in rats using stereotactic infusions of 0.5 U of collagenase (1-microL volume) into the striatum. After 24 hours, large numbers of TUNEL-positive stained cells with morphologies suggestive of apoptosis were present in the center and periphery of the hemorrhage. Double staining with Nissl and immunocytochemical labeling with antibodies against neuronal nuclei and glial fibrillary acidic protein suggested that these TUNEL-positive cells were mostly neurons and astrocytes. Electrophoresis of hemorrhagic brain extracts showed evidence of DNA laddering into approximately 200-bp fragments. Western blots showed cleavage of the cytosolic caspase substrate gelsolin. The density of TUNEL-positive cells at 24 and 48 hours after hemorrhage was significantly reduced by treatment with the broad-spectrum caspase inhibitor zVADfmk. It was unlikely that apoptotic changes were due to neurotoxicity of injected collagenase because TUNEL-positive cells and DNA laddering were also obtained in an alternative model of hemorrhage where autologous blood was infused into the striatum. Furthermore, equivalent doses of collagenase did not induce cell death in primary neuronal cultures. These results provide initial evidence that apoptotic mechanisms may mediate some of the injury in brain after intracerebral hemorrhage.

[Acute promyelocytic leukemia cell differentiation induced by tanshinone II A and its molecular mechanism]

OBJECTIVE

To investigate APL cell differentiation induced by tanshinone II (Tan II A) and its molecular mechanism.

METHODS

In vitro incubation of NB4 cells with Tan II A at the concentration of 0.5 microg/ml for 5 days, the cell differentiation was observed by cytomorphology, and nitroblue tetrazolium (NBT) test. Cell cycle, membrane CD(33), CD(11b) antigens and gene expressions (c-myc, c-fos, p53 and bcl-2) were analysed by flow cytometry.

RESULTS

(91.3 +/- 2.1)% of NB4 cells were induced into morphologically and functionally more differentiated cells including 0.26 of myelocytes and metamyelocytes, and 0.68 of band form and neutrophils. Cell growth curve showed that growth of NB4 cells were inhibited. NBT reduction was significantly increased. Expression of CD(33) decreased and CD(11b) increased. The degrees of cell differentiation and growth inhibition induced by Tan II A or ATRA were no difference. Flow cytometry analysis showed that Tan II A arrested NB4 cell in G(0)/G(1) phase, inhibited cellular DNA synthesis, down-regulated c-myc and bcl-2 genes expression, and up-regulated c-fos and p53 genes expression.

CONCLUSION

Tan II A can induce differentiation and growth inhibition of NB4 cells. Its possible molecular mechanism might relate to modulation of gene expressions associated proliferation and differentiation, and to inhibition of DNA synthesis.

Effects of tissue type plasminogen activator in embolic versus mechanical models of focal cerebral ischemia in rats

Tissue type plasminogen activator (tPA) can be effective therapy for embolic stroke by restoring cerebral perfusion. However, a recent experimental study showed that tPA increased infarct size in a mouse model of transient focal ischemia, suggesting a possible adverse effect of tPA on ischemic tissue per se. In this report, the effects of tPA in two rat models of cerebral ischemia were compared. In experiment 1, rats were subjected to focal ischemia via injection of autologous clots into the middle cerebral artery territory. Two hours after clot injection, rats were treated with 10 mg/kg tPA or normal saline. Perfusion-sensitive computed tomography scanning showed that tPA restored cerebral perfusion in this thromboembolic model. Treatment with tPA significantly reduced ischemic lesion volumes measured at 24 hours by >60%. In experiment 2, three groups of rats were subjected to focal ischemia via a mechanical approach in which a silicon-coated filament was used intraluminally to occlude the origin of the middle cerebral artery. In two groups, the filament was withdrawn after 2 hours to allow for reperfusion, and then rats were randomly treated with 10 mg/kg tPA or normal saline. In the third group, rats were not treated and the filament was not withdrawn so that permanent focal ischemia was present. In this experiment, tPA did not significantly alter lesion volumes after 2 hours of transient focal ischemia. In contrast, permanent ischemia significantly increased lesion volumes by 55% compared with transient ischemia. These results indicate that in these rat models of focal cerebral ischemia, tPA did not have detectable negative effects. Other potentially negative effects of tPA may be dependent on choice of animal species and model systems.

[Iodine therapy for iodine deficiency goiter and autoimmune thyroiditis. A prospective study]

PROBLEM

There is epidemiological and clinical evidence that iodine may induce or promote the manifestation of autoimmune thyroiditis. For this reason it is important to know if substitution of alimentary iodine deficiency or iodine treatment of endemic goitre can cause formation of thyroid antibodies. On the other hand the practical importance of this phenomenon should be evaluated.

PATIENTS AND METHODS

During a prospective study we examined 209 patients with endemic non-toxic goitre and 53 healthy people. For treatment were used 200 micrograms iodine/d (n = 119), 500 micrograms iodine/d (n = 27), 1.5 mg iodine/week (n = 41), 150 micrograms iodine/d plus 75 to 100 micrograms T4/d (n = 26), 100 micrograms iodine plus 100 micrograms T4/d (n = 24). The observation took 1 year with a 3-month interval for check ups including clinical examination, ultrasound, TSH, T3, fT4, TPO- and thyreoglobuline antibodies and urinary iodine.

RESULTS

After 12 months 7.5% of iodine treated persons had produced antibodies, most of them at low levels. In healthy people we found increased antibody-levels in 3.8%, in patients with goitre in 9.0%, in patients with nodular goitres in 11.1%. 500 micrograms iodine caused the most antibody reaction in 14.8%. People treated with 200 micrograms iodine/d showed positive antibody levels in 5%. T4 seems to reduce antibody-reactions. Pathological antibody-levels were not found in patients with combined iodine/T4- and single-T4 therapy. Among the 22 primary pathological antibody levels only 4 increased further (18.2%). Three of them belonged to the group of 5 persons treated with 500 micrograms iodine/d. Primary high antibody values were normalized in 5 patients (22.7%). Hypothyroid disturbances were not found. Ultrasound did not show any alterations, and the reduction of thyroid volumes in antibody-positive patients was not affected. Median urinary iodine excretion during the observation-interval was 5.2 to 7.2 micrograms/dl.

CONCLUSIONS

Possible antibody reactions have no clinical importance at all. Individual cases must be observed. Low iodine doses should be preferred. Combined iodine/T4 treatment seems to have an advantage regarding immunological thyroidal reactions.

[Effect of in vitro interferon on bone marrow megakaryocyte in patients with idiopathic thrombocytopenic purpura]

The effect of rIFN alpha-2a on the megakaryocyte colony growth and maturation was observed in 33 patients with idiopathic thrombocytopenic purpura (CITP) in vitro by plasma clot cultures and by GP III a McAb and ABC kit. Twenty five healthy persons were in the control group. The results showed that the number of colony formation units of megakaryocyte in the patients was similar to that in the controls, but the diameter and area levels of megakaryocyte in the patients were lower. The ratio of inhibition of rIFN alpha-2a on megakaryocyte progenitors colony growth was significantly lower in the patients and was lowest in the group with increasing number of megakaryocytes on bone marrow smear. The rIFN alpha-2a had no effect on promoting the megakaryocyte maturation. Since this study has indicated that the inhibition of rIFN alpha-2a on colony formation unit of megakaryocyte is slight in CITP, interferon therapy should be a suitable prescription for the CITP patients who have an increasing number of megakaryocyte on bone marrow smear.

Generation of human T-cell responses to an HLA-A2.1-restricted peptide epitope derived from alpha-fetoprotein

Alpha-fetoprotein (AFP) is often derepressed in human hepatocellular carcinoma. Peptide fragments of AFP presented in the context of major histocompatibility molecules could serve as potential recognition targets by CD8 T cells, provided these lymphocytes were not clonally deleted in ontogeny. We therefore wished to determine whether the human T-cell repertoire could recognize AFP-derived peptide epitopes in the context of a common class I allele, HLA-A2.1. Dendritic cells genetically engineered to express AFP were capable of generating AFP-specific T-cell responses in autologous human lymphocyte cultures and in HLA-A2.1/Kb transgenic mice. These T cells recognize a 9-mer peptide derived from the AFP protein hAFP(542-550) (GVALQTMKQ). Identified as a potential A2.1-restricted peptide epitope from a computer analysis of the AFP sequence, hAFP(542-550) proved to have low binding affinity to A2.1, but slow off-kinetics. AFP-specific CTL- and IFN-gamma-producing cells recognize hAFP(542-550)-pulsed targets. Conversely, hAFP(542-550) peptide-generated T cells from both human lymphocyte cultures and A2.1/Kb transgenic mice recognized AFP-transfected targets in both cytotoxicity assays and cytokine release assays. These lines of evidence clearly demonstrate that AFP-reactive clones have not been deleted from the human T-cell repertoire and identify one immunodominant A2.1-restricted epitope. These findings also clearly establish AFP as a potential target for T-cell-based immunotherapy.

[Carl Adolph von Basedow--on the 200th anniversary of his birth]

Carl Adolph von Basedow was the son of an aristocratic family and was born 1799 in Dessau. He was the grandson of the famous pedagogue Johann Bernhard Basedow. He studied medicine at the university of Halle and spent two years in the surgical service of Paris hospitals--the Charité and the Hôtel Dieu. In 1822, he settled in Merseburg as a physician. He was soon acclaimed as a genial and skilled helper in all branches of medical practice. He performed his own post-mortem examinations and published findings on a number of different diseases. His famous contribution in the thyroid field appeared in 1840 entitled "Exophthalmos due to hypertrophy of the cellular tissue in the orbit". Exophthalmos, goiter and palpitation of the heart have become known as the Merseburg Triad. In 1848, he published the autopsy findings on a patient who died from "exophthalmic cachexia". In Germany and some other countries, the disease was named as Morbus Basedow since 1858. In 1854 he pricked in his finger in the postmortem room when examining a patient who had died of typhus and he succumbed to septicemia at the early age of fifty-five. The date of his death was April 11, 1854. On April 14, he was laid in the Sixtus Cemetery in Merseburg. Basedow postulated that a wrong mixing of the blood manifested in cell tissue congestion and glandular vegetation cause the manifestations of disease. If we abstract our modern knowledge and accept circulating antibodies and disturbance of the immune balance as a dyscrasia as well as the proliferation of lymphocytic clones and local cellulary infiltration in terms of immune thyroiditis and autoimmune orbitopathy as cell tissue congestion and glandular vegetations, then doubt arise whether we have indeed made much progress in the last 150 years. At least, respect for the genius of the general physician Carl Adolph von Basedow is becoming greater. We may all hope that in the contributions and the discussions, we shall learn where we stand at the end of the century and what new avenues of research are appearing on the horizon.

Structure of the amino-terminal domain of Cbl complexed to its binding site on ZAP-70 kinase

Cbl is an adaptor protein that functions as a negative regulator of many signalling pathways that start from receptors at the cell surface. The evolutionarily conserved amino-terminal region of Cbl (Cbl-N) binds to phosphorylated tyrosine residues and has cell-transforming activity. Point mutations in Cbl that disrupt its recognition of phosphotyrosine also interfere with its negative regulatory function and, in the case of v-cbl, with its oncogenic potential. In T cells, Cbl-N binds to the tyrosine-phosphorylated inhibitory site of the protein tyrosine kinase ZAP-70. Here we describe the crystal structure of Cbl-N, both alone and in complex with a phosphopeptide that represents its binding site in ZAP-70. The structures show that Cbl-N is composed of three interacting domains: a four-helix bundle (4H), an EF-hand calcium-binding domain, and a divergent SH2 domain that was not recognizable from the amino-acid sequence of the protein. The calcium-bound EF hand wedges between the 4H and SH2 domains and roughly determines their relative orientation. In the ligand-occupied structure, the 4H domain packs against the SH2 domain and completes its phosphotyrosine-recognition pocket. Disruption of this binding to ZAP-70 as a result of structure-based mutations in the 4H, EF-hand and SH2 domains confirms that the three domains together form an integrated phosphoprotein-recognition module.

[MMC conditioning regimen (Melphalan, MeCCNU and cyclophosphamide) followed by allogeneic peripheral blood stem cells transplantation for chronic myeloid leukemia]

This paper reports 3 cases of allogeneic peripheral blood stem cell transplantation (Allo-PBSCT) for the patients with chronic myeloid leukemia (CML). The patients received MMC preparative regimen with high dose chemotherapy (Melphalan 170 mg/m2, p.o. on Day-5, MeCCNU 400 mg/m2, p.o. on Day-4, and Cyclophosphomide 60 mg/kg/day, i.v. on Days-3 and -2). The HLA-identical sibling donors received filgrastim (rhG-CSF) for mobilization at a dose of 300 micrograms/day for 6 days. Leukaphereses were done at the 6th day of mobilization. A median of 8000 ml (2 times total blood volume) of blood was processed the collecting: 2.5-4.5 x 10(8)/kg MNC, 12.8-20.0 x 10(6)/kg CD34+ cells (including 4.8-7.5 x 10(6)/kg CD34+CD33-, 8.0-13.0 x 10(6)/kg CD34+CD33+), and 3.5-4.3 x 10(5)/kg CFU-GM. Cyclosporin A and methotrexate were used for GVHD prophylaxis. Hematopoitic function recovered as for 14-20 days to > 0.5 x 10(9)/L of neutrophil count, and for 16-34 days to > 20 x 10(9)/L of platelet count. At day + 100, chromosome analysis of bone marrow cells showed that complete chimera without ph1 positive chromosome in Cases 1 and 3, and a partial chimera with 73% donor karyotype in Case 2. All patients now are in disease free survival. No episode of acute graft versus host disease (GVHD) developed. It was concluded that HLA matched sibling allogeneic PBSCT result in rapid hematopoitic reconstitution and the MMC conditioning regimen is effective both in leukemic cells eradication and in immunosuppression for stem cells engraftment, and the drug related toxicity could be tolerated by patients.

Characterization of mitochondrial glutaminase and amino acids at prolonged times after experimental focal cerebral ischemia

The mitochondrial enzyme glutaminase is a significant contributor to extracellular glutamate after neuronal injury in vitro [R. Newcomb, X. Sun, L. Taylor, N. Curthoys, R.G. Giffard, Increased production of extracellular glutamate by the mitochondrial glutaminase following neuronal death, J. Biol. Chem. 272 (1997) 11276-11282.]. As a step towards characterizing the role of the enzyme in neuronal injury in vivo, glutaminase activity was measured in central and peripheral regions of the ischemic distribution in rat brain at 6, 24, and 48 h after permanent focal ischemia. Although glutaminase activity decreases in the central ischemic area, significant activity remains in peripheral areas of evolving damage, even after 24 and 48 h ischemia. Western blots show no detectable change in glutaminase molecular weight or total immunoreactivity, regardless of the degree of inactivation. Significant amounts of glutamine remain in ischemic tissue at prolonged times after focal ischemia, while reductions in tissue amounts of glutamate are highly correlated with decreases in glutaminase activity. In vivo microdialysis probes were inserted into the ischemic periphery after 24 h focal ischemia. Glutamate is significantly elevated in these dialysates. Perfusion of the glutaminase substrate glutamine and the enzyme activator phosphate results in further and specific elevations in dialysate glutamate. In sum, significant mitochondrial glutaminase activity remains in the periphery of the ischemic lesion at 24 and 48 h, where it can contribute directly to elevated extracellular glutamate. Inactivation of the glutaminase in central areas of the ischemic lesion does not involve significant proteolytic degradation, and likely involves a specific molecular event.

Crystal structure of the catalytic domain of protein-tyrosine phosphatase SHP-1

The crystal structures of the protein-tyrosine phosphatase SHP-1 catalytic domain and the complex it forms with the substrate analogue tungstate have been determined and refined to crystallographic R values of 0.209 at 2.5 A resolution and 0.207 at 2.8 A resolution, respectively. Despite low sequence similarity, the catalytic domain of SHP-1 shows high similarity in secondary and tertiary structures with other protein-tyrosine phosphatases (PTPs). In contrast to the conformational changes observed in the crystal structures of PTP1B and Yersinia PTP, the WPD loop (Trp419-Pro428) in the catalytic domain of SHP-1 moves away from the substrate binding pocket after binding the tungstate ion. Sequence alignment and structural analysis suggest that the residues in the WPD loop, especially the amino acid following Asp421, are critical for the movement of WPD loop on binding substrates and the specific activity of protein-tyrosine phosphatases. Our mutagenesis and kinetic measurements have supported this hypothesis.

[Renal iodine excretion by students in East Germany. A prospective study 1989 to 1996]

AIM

A prospective longitudinal study was performed from 1989 to 1996 in order to check the effectiveness of prophylactic measures in Germany.

TEST PERSONS AND METHODS

In 3 periods the urinary iodine excretion was examined in 1849 adolescents from 2 regions (north, south) of former Eastern Germany.

RESULTS

The consumption of iodized salt has increased substantially since 1994. This coincides with an increase in urinary iodine excretion. The median iodine excretion found in 1989/92 (n = 744) was 39.0 micrograms/g creatinine (4.7 micrograms/dl), in 1994 (n = 123) 60.1 micrograms/g creatinine (6.0 micrograms/dl), and in 1995/96 (n = 982) 101.1 micrograms/g creatinine (9.8 micrograms/dl). However, the concentration was < 5.0 micrograms in 27.8% and < 10.0 micrograms iodine/dl in 58.0%. Regional differences were not found.

CONCLUSION

The iodine supply has been improved. However, the declared targets have not yet been met. The findings show that effective goitre prophylaxis can still be achieved while maintaining the voluntary principle.

Inhibition of poly(ADP-ribose) polymerase: reduction of ischemic injury and attenuation of N-methyl-D-aspartate-induced neurotransmitter dysregulation

BACKGROUND AND PURPOSE

The nuclear enzyme poly(ADP-ribose) polymerase (PARP) may play a role in DNA repair. However, in cerebral ischemia, excessive PARP activation may lead to energy depletion and exacerbation of neuronal damage. We examined the effect of inhibiting PARP on (1) the degree of cerebral injury in a rat model of transient focal ischemia and (2) the degree of neurotransmitter dysregulation induced by local cortical perfusion of N-methyl-D-aspartate (NMDA).

METHODS

In experiment 1, rats were subjected to transient ischemia for 90 minutes by occlusion of the middle cerebral artery. After 22.5 hours of reperfusion, lesions were quantified by tetrazolium staining. Untreated rats were compared with those treated with the PARP inhibitor 3-aminobenzamide (10 mg/kg). In experiment 2, rats were implanted with microdialysis probes in the cortex, and 1 mmol/L NMDA was perfused for 2 hours. Extracellular concentrations of neurotransmitter and neuromodulator amino acids were measured. Untreated rats were compared with those given 10 mg/kg 3-aminobenzamide.

RESULTS

In experiment 1, PARP inhibition significantly reduced lesion volumes: 204+/-43 mm3 (untreated) versus 90+/-24 mm3 (treated). Neuroprotection was primarily manifested in the cortex. In experiment 2, NMDA perfusion resulted in large elevations of glutamate, taurine, and the lipid component phosphoethanolamine. Levels of the NMDA site modulator D-serine were reduced, and glycine levels appeared unchanged. 3-Aminobenzamide significantly attenuated the elevations in glutamate and phosphoethanolamine but had no effects on D-serine and glycine.

CONCLUSIONS

Inhibition of PARP reduced injury after transient focal ischemia in rats and attenuated NMDA-induced glutamate efflux and overall neurotransmitter dysregulation. The deleterious effects of excessive PARP activation may be related in part to amplification of excitotoxicity, possibly by cellular energy depletion and additional transmitter release and/or reduced reuptake.

Neuronal NOS-cGMP-dependent ACh-induced relaxation in pial arterioles of endothelial NOS knockout mice

We evaluated the effects of superfusing 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), eNOS null (B) an inhibitor of soluble guanylyl cyclase, and 7-nitroindazole sodium (7-NI), a selective neuronal nitric oxide synthase (nNOS) inhibitor, on the acetylcholine (ACh) response in endothelial NOS (eNOS) null mice. Pial arteriolar diameter was measured by intravital microscopy through a closed cranial window under alpha-chloralose anesthesia. NOS activity was measured by [3H]arginine-to-[3H]citrulline conversion in subjacent cortex in vitro. The density and distribution of muscarinic receptors in the brain were determined by quantitative [3H]quinuclidinyl benzilate autoradiography and did not differ between the eNOS mutants and wild-type mice. ACh superfusion (1 and 10 microM) dose dependently dilated pial arterioles in eNOS null and wild-type mice. ODQ (10 microM) attenuated ACh-induced dilation in both eNOS mutants (41% decrease at 10 microM ACh, P < 0.01, n = 6) and wild-type strains (n = 5 per group). By contrast, topical superfusion of 7-NI (100 microM) attenuated the ACh response in eNOS mutants only (66%, P < 0.05, and 25% decrease, P < 0.05, at 1 and 10 microM ACh, respectively). Our findings suggest that nNOS-guanosine 3',5'-cyclic monophosphate (cGMP)-dependent pathways dilate pial arterioles by compensatory mechanisms after eNOS gene disruption.

[Nutritional iodine supply in Germany. Results of preventive measures]

Germany is an iodine deficiency area with endemic goitre. The prophylactic procedures which have been initiated gradually since 1983, were different between the eastern and western part of Germany. In East Germany iodine supply could be improved by "mandatory prophylaxis" until 1989. However, after the reunification of Germany and the adaption of the "voluntary principle", the iodine intake decreased again. In December 1993, new regulations concerning iodized salt became effective (so called "2nd decree") combined with a relaxation of the declaration of duty. This relaxation considerably contributed to the significant increase in iodized salt utilisation in food production. The rise of iodine content of food and breast milk, the higher iodine intake with food, the decrease of fetal thyroid volume and the increase in renal iodine excretion are clear indicators of a better iodine supply. However, the desired target figures have not been obtained yet.

Expression, purification, and crystallization of the catalytic domain of protein tyrosine phosphatase SHP-1

The catalytic domain of SHP-1, a SH2-domain containing protein tyrosine phosphatase, has been crystallized by the vapor diffusion method using polyethylene glycol as the precipitant. The crystals belong to the monoclinic space group P21 with unit cell dimensions a = 42.12 A, b = 87.94 A, c = 43.22 A, alpha = 90.0 degrees, beta = 120.12 degrees, and gamma = 90.0 degrees. There is one catalytic domain of SHP-1 per asymmetric unit. X-ray was diffracted to at least 2.5 A and the crystals are appropriate for high-resolution structure determination.

[Experimental study of distribution of stress and strain on pelvis in normal Chinese adult]

To approach the biomechanical properties of pelvis in normal Chinese adult, an intact pelvis taken from fresh healthy male cadaver after sudden death was used in this study. The pelvis joined up with lumber4, 5 and proximal segment of femurs. After appropriate management of the specimen, the loads in the simulated test (stand position of normal adult) are 300 N, 600 N and 900 N. With strain electric measuring apparatus, the distribution of stress and strain, and the actual linear strain of every measuring point are obtained. Data processing was performed on computer. The main stress sigma 1, sigma 2 and their direction angles were acquired. The results of the simulated test demonstrated that the stress of iliac bone adjacent to sacro-iliac articulation was maximum in all measuring points. The linear strain values of 0 degree direction parallel with coronal section were negative in majority, but those of 45 degrees and 90 degrees direction vertical with coronal section were positive in majority. So the distribution of the linear strain of pelvis should be very complicated. When 900 N weight acted on the pelvis, the maximum main stress sigma max = 0.269-20.01 MPa and the minimum main stress sigma min = -0.095(-)-16.56 MPa. The angle of the maximum main stress with coronal section did not exceed 4 degrees.

Strain-related differences in susceptibility to transient forebrain ischemia in SV-129 and C57black/6 mice

BACKGROUND AND PURPOSE

We explored susceptibility to injury after global ischemia in SV-129 and C57Black/6 mice, two commonly used-background strains in genetically engineered mice.

METHODS

Mice (n = 84) were subjected to 15, 30, or 75 minutes of bilateral common carotid artery (BCCA) occlusion followed by reperfusion for 72 hours. BCCA occlusion was performed under halothane or chloral hydrate anesthesia, in one experiment, mean arterial blood pressure and regional cerebral blood flow (laser Doppler flowmetry) were matched by controlled exsanguination. Baseline absolute blood flow measurements were obtained in both strains using a tracer, N-isopropyl-[methyl 1,3-14C]-p-iodoamphetamine, indicator fractionation technique (n = 5 per group). Vascular anatomy of the circle of Willis was visualized by intravascular perfusion of carbon black ink (n = 10 per group). Cerebrovascular reactivity was assessed by measuring the diameter of pial vessels (intravital microscopy) to acetylcholine (ACh) superfusion (0.1 to 10 mmol/L) in a closed cranial window preparation (n = 29).

RESULTS

Resting blood flow values did not differ between groups in striatum, cerebellum, and brain-stem regions. SV-129 mice were less susceptible than C57Black/6 mice to ischemic injury (0.0 +/- 0.0 versus 1.3 +/- 0.3 damage in hippocampal CA1 region after 30 minutes of ischemia in SV-129 and C57Black/6, respectively; P < .01). Cellular damage (grade 1 to 3 injury) comparable to 30-minute BCCA occlusion was achieved only after 75 minutes of ischemia in SV-129 mice (1.1 +/- 0.3). Ischemic damage was also significantly less in SV-129 mice after blood pressure and flow were matched during ischemia in halothane-anesthetized SV-129 mice (0.5 +/- 0.3 versus 1.4 +/- 0.2, P < .05), or after chloral hydrate anesthesia (0.4 +/- 0.2 versus 1.5 +/- 0.4, P < .05). Hypoplastic posterior communicating arteries were found in all 10 C57Black/6 mice and may explain the greater susceptibility of these mice to injury after BCCA occlusion. More robust vasodilation to ACh in C57Black/6 mice could also indicate genetic differences in responses to vasoactive substances.

CONCLUSIONS

C57Black/6 mice exhibit enhanced susceptibility to global cerebral ischemic injury, an incompletely formed circle of Willis, and augmented pial vessel dilation to ACh compared with SV-129 mice. Our findings suggest that strain differences may confound results when genetically engineered mice generated from more than a single background strain are used.

[Maturation of bone marrow megakaryocyte in patients with chronic idiopathic thrombocytopenic purpura]

Colony formation units of megakaryocyte of twenty four patients with idopathic thromboeytopentic purpura (CITP) were observed by plasma clot cultures in vitro. We observed the maturation degree of megakarycyte and the effect of recombinant interferon alpha-2a (rIFN-alpha-2a) on megakaryocyte colony growth and maturation. The results showed that the number of CFU-MK of the patients with CITP was greater than that of the control group, while the patients with normal number of megakaryocytes on bone marrow smears had less BFU-MK and total clonies than the controls had. Through image analysis, we found that the black level of the positive cells of GP II a and GMP-140, the diameter and the area of megakaryocyte of patients with CITP were lower or smaller than those of the control group. These evidenced the block of megakaryocytopoiesis and megakarycyte maturation. The growth of MK colonies of marrow of patients with CITP was inhibited by r-IFN-alpha-2a.

Domain-specific N-glycosylation of the membrane glycoprotein dipeptidylpeptidase IV (CD26) influences its subcellular trafficking, biological stability, enzyme activity and protein folding

Dipeptidyl peptidase IV (DPPIV, CD26) is an N-glycosylated type II plasma membrane protein. The primary structure of rat wild-type DPPIV contains eight potential N-glycosylation sites. To investigate the role of N-glycosylation in the function of DPPIV, three of its asparagine residues were separately converted to glutamine by site-directed mutagenesis. The resulting N-glycosylation mutants of rat DPPIV were studied in stable transfected Chinese hamster ovary cells. All three N-glycosylation mutants of DPPIV showed a reduced half-life, as well as differing degrees of inhibition of the processing of their N-glycans. Mutation of the first (Asn83-->Gln) or eighth (Asn686-->Gln) N-glycosylation site had only a small effect on its enzymatic activity, cell-surface expression and dimer formation, whereas the mutation of the sixth N-glycosylation site (Asn319-->Gln) abolished the enzymatic activity, eliminated cell-surface expression and prevented the dimerization of the DPPIV protein. The mutant [Gln319]DPPIV is retained in the cytoplasm and its degradation was drastically increased. Our data suggest that the N-glycosylation at Asn319 is involved in protein trafficking and correct protein folding.

[Structure determination of new antifungal antibiotics, polaramycins A and B]

Antifungal antibiotics, polaramycins A and B have been isolated from the culture of Streptomyces hygroscopicus LP-93. Polaramycins A and B are 36-membered polyol macrolide antibiotics containing hemiacetal monoester of malonic acid and guanidyl groups. Based on spectral evidence including UV, IR, FABMS, 1HNMR, 13CNMR, DEPT, 1H-1H COSY, HETCOR, HMBC, the structure of polaramycins A and B have been assigned as shown in Fig 1 (A, R = H; B, R = CH3).

Isoflurane-induced cerebral hyperemia in neuronal nitric oxide synthase gene deficient mice

BACKGROUND

Nitric oxide (NO) has been reported to play an important role in isoflurane-induced cerebral hyperemia in vivo. In the brain, there are two constitutive isoforms of NO synthase (NOS), endothelial NOS (eNOS), and neuronal NOS (nNOS). Recently, the mutant mouse deficient in nNOS gene expression (nNOS knockout) has been developed. The present study was designed to examine the role of the two constitutive NOS isoforms in cerebral blood flow (CBF) response to isoflurane using this nNOS knockout mouse.

METHODS

Regional CBF (rCBF) in the cerebral cortex was measured with laser-Doppler flowmetry in wild-type mice (129/SV or C57BL/6) and nNOS knockout mice during stepwise increases in the inspired concentration of isoflurane from 0.6 vol% to 1.2, 1.8, and 2.4 vol%. Subsequently, a NOS inhibitor, N omega-nitro-L-arginine (L-NNA), was administered intravenously (20 mg/kg), and 45 min later, the rCBF response to isoflurane was tested again. In separate groups of wild-type mice and the knockout mice, the inactive enantiomer, N omega-nitro-D-arginine (D-NNA) was administered intravenously in place of L-NNA. Brain NOS activity was measured with radio-labeled L-arginine to L-citrulline conversion after treatment with L-NNA and D-NNA.

RESULTS

Isoflurane produced dose-dependent increases in rCBF by 25 +/- 3%, 74 +/- 10%, and 108 +/- 14% (SEM) in 129/SV mice and by 32 +/- 2%, 71 +/- 3%, and 96 +/- 7% in C57BL/6 mice at 1.2, 1.8, and 2.4 vol%, respectively. These increases were attenuated at every anesthetic concentration by L-NNA but not by D-NNA. Brain NOS activity was decreased by 92 +/- 2% with L-NNA compared with D-NNA. In nNOS knockout mice, isoflurane increased rCBF by 67 +/- 8%, 88 +/- 12%, and 112 +/- 18% at 1.2, 1.8, and 2.4 vol%, respectively. The increase in rCBF at 1.2 vol% was significantly greater in the nNOS knockout mice than that in the wild-type mice. Administration of L-NNA in the knockout mice attenuated the rCBF response to isoflurane at 1.2 and 1.8 vol% but had no effect on the response at 2.4 vol%.

CONCLUSIONS

In nNOS knockout mice, the cerebral hyperemic response to isoflurane is preserved by compensatory mechanism(s) that is NO-independent at 2.4 vol%, although it may involve eNOS at 1.2 and 1.8 vol%. It is suggested that in wild-type mice, eNOS and nNOS contribute to isoflurane-induced increase in rCBF. At lower concentrations (1.2 and 1.8 vol%), eNOS may be involved, whereas at 2.4 vol%, nNOS may be involved.

Neuronal NO promotes cerebral cortical hyperemia during cortical spreading depression in rabbits

Temporary elevations in cortical cerebral blood flow (CBF) accompany cortical spreading depression (CSD) in anesthetized animals. We tested the hypothesis that nitric oxide (NO) is an important promotor of CSD-induced cortical hyperemia in urethan-anesthetized rabbits. CBF was measured at four time points by administration of 15-microm microspheres with the reference withdrawal technique. Intravenous administration of the nonspecific NO synthase (NOS) inhibitor N(omega)-nitro-L-arginine increased mean arterial blood pressure and resting cerebrovascular resistance and attenuated CSD-induced hyperemia. Cortical CBF before intraperitoneal 7-nitroindazole (7-NI), a neuronal NOS inhibitor, was 42 +/- 8 and 124 +/- 19 ml x 100 g(-1) x min(-1) at baseline and during CSD, respectively (P < 0.05 by repeated-measures analysis of variance). After 7-NI administration, mean arterial blood pressure, CBF, and cerebrovascular resistance were unchanged from baseline values; cortical CBF was 38 +/- 4 and 90 +/- 8 ml x 100 g(-1) x min(-1) post-7-NI at rest and during a second CSD, respectively. Similar to N(omega)-nitro-L-arginine, 7-NI decreased the cortical hyperemic response during CSD (P < 0.05 by repeated-measures analysis of variance). We conclude that neuronal NOS promotes the temporary cortical hyperemia observed during CSD.

Crystal structure determination of basic phospholipase A2 from venom of Agkistrodon halys pallas by molecular replacement method

Basic phospholipase A2 (BPLA2) from the venom of Agkistrodon halys pallas has a strong ability to hemolyze erythrocytes. The asymmetrical unit of P2(1)2(1)2(1) crystal of BPLA2 contains two molecules. Self-rotation function was used to study the orientation relationship of these two molecules. Cross-rotation and translation functions were then used to determine the orientations and positions of the two molecules in the unit cell. The model building and preliminary structure refinement were carried out. The result shows that the two molecules in the asymmetrical unit of orthorhombic crystal are related by a non-crystallographic 2-fold symmetry axis.

Global ischemia impairs ATP-sensitive K+ channel function in cerebral arterioles in piglets

BACKGROUND AND PURPOSE

Indirect evidence from studies in which calcitonin gene-related peptide was used indicates that anoxic stress suppresses functioning of cerebral vascular ATP-sensitive K+ channels. The purpose of this study was to directly examine effects of total global ischemia on cerebral arteriolar dilator responses to activators of ATP-sensitive K+ channels.

METHODS

We measured pial arteriolar diameters in anesthetized piglets using a closed cranial window and intravital microscopy. Baseline diameters were approximately 100 microns. Arteriolar responses to aprikalim (10(-8) and 10(-6) mol/L), a pharmacological activator of ATP-sensitive K+ channels, and iloprost (0.1 and 1 microgram/mL), a physiological activator of these channels, were determined before and 1, 2, and 4 hours after a 10-minute period of total global ischemia. Ischemia was caused by increasing intracranial pressure.

RESULTS

Before ischemia, aprikalim dilated cerebral arterioles by 7 +/- 2% at 10(-8) mol/L and by 25 +/- 4% at 10(-6) mol/L (n = 5). At 1 hour after ischemia, aprikalim did not cause significant dilation at either dose (3 +/- 2% at 10(-8) mol/L and 7 +/- 4% at 10(-6) mol/L; P < .05 compared with corresponding preischemic response). Arteriolar dilation returned toward normal values at 2 and 4 hours. Similar results were found with iloprost. Furthermore, prior treatment with indomethacin (5 mg/kg) preserved normal arteriolar dilation to aprikalim and iloprost after ischemia. In contrast, arteriolar dilator responses to prostaglandin E2 were intact after ischemia.

CONCLUSIONS

Ischemia transiently eliminates cerebral arteriolar dilation to activation of ATP-sensitive K+ channels; arteriolar responses are suppressed at 1 hour and return toward normal over 2 to 4 hours. In addition, reduced responsiveness can be prevented by prior treatment with indomethacin.

L-NNA-sensitive regional cerebral blood flow augmentation during hypercapnia in type III NOS mutant mice

The effect of NG-nitro-L-arginine (L-NNA) on regional cerebral blood flow (rCBF) response to hypercapnia (5% CO2 inhalation) was studied in urethan-anesthetized wild-type (SV-129) and type III nitric oxide (NO) synthase (NOS)-deficient mice, using laser-Doppler flowmetry and the closed cranial window technique. Resting rCBF during normocapnia decreased by approximately 25% after L-NNA superfusion in wild-type mice only (n = 18), suggesting a role for type III NOS in baseline blood flow. Hypercapnia augmented rCBF approximately 50% in both wild-type and type III NOS mutant mice. L-NNA superfusion (1 mM) inhibited this increase by approximately 60% in both strains. Hence, synthesis of NO by the constitutively expressed type I NOS contributes to blood flow augmentation during hypercapnia.

Enlarged infarcts in endothelial nitric oxide synthase knockout mice are attenuated by nitro-L-arginine

Infarct size and vascular hemodynamics were measured 24 h after middle cerebral artery (MCA) occlusion in mice genetically deficient in the endothelial nitric oxide synthase (eNOS) isoform. eNOS mutant mice developed larger infarcts (21%) than the wild-type strain when assessed 24 h after intraluminal filament occlusion. Moreover, regional CBF values recorded in the MCA territory by laser-Doppler flowmetry were more severely reduced after occlusion and were disproportionately reduced during controlled hemorrhagic hypotension in autoregulation experiments. Unlike the situation in wild-type mice, nitro-L-arginine superfusion (1 mM) dilated pial arterioles of eNOS knockout mice in a closed cranial window preparation. As noted previously, eNOS mutant mice were hypertensive. However, infarct size remained increased despite lowering blood pressure to normotensive levels by hydralazine treatment. Systemic administration of nitro-L-arginine decreased infarct size in eNOS mutant mice (24%) but not in the wild-type strain. This finding complements published data showing that nitro-L-arginine increases infarct size in knockout mice expressing the eNOS but not the neuronal NOS isoform (i.e., neuronal NOS knockout mice). We conclude that NO production within endothelium may protect brain tissue, perhaps by hemodynamic mechanisms, whereas neuronal NO overproduction may lead to neurotoxicity.

ACh dilates pial arterioles in endothelial and neuronal NOS knockout mice by NO-dependent mechanisms

We used mice with deletions in either the endothelial nitric oxide synthase (eNOS) or neuronal NOS (nNOS) gene to investigate the role of eNOS and nNOS in acetylcholine (ACh)-induced relaxation of pial arterioles (20-30 microns). Pial arteriolar diameter was measured by intravital microscopy through a closed cranial window, and NOS activity was determined by the conversion of [3H]arginine to [3H]citrulline in subjacent cortex. ACh superfusion (1, 10 microM) caused atropine-sensitive dose-dependent arteriolar dilation in all three mouse strains. At 10 microM, increases of 20 +/- 2, 31 +/- 3, and 23 +/- 3% were recorded in wild-type (n = 25), nNOS mutant (n = 15), and eNOS mutant (n = 20) mice, respectively. NG-nitro-L-arginine (L-NNA, 1 mM) superfusion inhibited cortical NOS activity by > 70% and abrogated the response in wild-type mice while blocking the dilation by approximately 50% in eNOS mutant and nNOS mutant mice. Only in the eNOS mutant did tetrodotoxin (TTX) superfusion (1 microM) attenuate ACh-induced dilation (n = 6). The residual dilation after L-NNA in eNOS mutant mice could be blocked completely by TTX-plus L-NNA. Our findings indicate that 1) ACh dilates pial arterioles of wild-type mice by NOS-dependent mechanisms as reported in other species, 2) the response in nNOS mutant mice resembles the wild-type response except for enhanced dilation to ACh and reduced L-NNA sensitivity, and 3) surprisingly, the response in eNOS mutant mice is partially NOS dependent and attenuated by both TTX and L-NNA. Because nNOS is constitutively expressed in eNOS mutants, these findings coupled with the TTX results suggest that an nNOS-dependent mechanism may compensate for the chronic loss of eNOS activity after targeted gene disruption.

L-NA-sensitive rCBF augmentation during vibrissal stimulation in type III nitric oxide synthase mutant mice

Regional cerebral blood flow (rCBF) was studied in type III nitric oxide (NO) synthase (endothelial, eNOS) mutant and wild type mice during mechanical whisker stimulation before and after nitro-L-arginine (L-NA) superfusion using the closed cranial window technique. rCBF increased equally in cortical barrel fields in both strains during stimulation, as measured by laser Doppler-flowmetry, and was inhibited by L-NA superfusion (1 mM) in both groups. Hence, coupling of blood flow and metabolism appears neuronal NOS-(nNOS) but not eNOS-dependent in cortical barrel fields of the mouse.

Effects of ischemia on cerebrovascular responses to N-methyl-D-aspartate in piglets

We examined the effects of total global ischemia on cerebral arteriolar responses to N-methyl-D-aspartate (NMDA) in anesthetized newborn pigs. Arteriolar responses to 10(-4) M NMDA were determined before and after 10 to 20 min of ischemia caused by increasing intracranial pressure. Before ischemia, NMDA dilated arterioles by 30 +/- 5% (baseline = 88 +/- 2 microns; n = 6). However, after 10 min of ischemia, arteriolar dilation was reduced to 10 +/- 3% at 1 h (P < 0.05). At 2 and 4 h, NMDA-induced dilation was not different from preischemia values. Twenty minutes of ischemia had similar effects. Coadministration of 100 U/ml of superoxide dismutase did not restore arteriolar dilation to NMDA at 1 h after ischemia. Sodium nitroprusside dilated by 14 +/- 3 and 40 +/- 5% at 10(-6) and 10(-5) M before ischemia, respectively, and arteriolar responsiveness was not changed by ischemia (n = 6). Cortical nitric oxide synthase (NOS) activity, measured by the in vitro conversion of L-[14C]arginine to L-[14C]citrulline, was unaffected by ischemia (n = 12). We conclude that decreases in cerebral arteriolar responsiveness to NMDA are not due to impairment of NOS activity, enhanced degradation or chelation of nitric oxide (NO), or reduced vascular smooth muscle responsiveness to NO.

[Duplex sonography in functional thyroid diagnosis]

PURPOSE

Assessment of the functional diagnostic value of Doppler sonographic or sonographic parameters, especially of the peak flow velocity in the inferior thyroid artery in patients with newly manifest autoimmunothyroiditis.

MATERIAL AND METHOD

Morphological and Doppler sonographic measurements were done at the inferior thyroid artery on 69 patients suffering from newly manifest Graves' disease or Hashimoto's thyroiditis, as well as on a control group of 18 subjects. The measured data were correlated with thyroid hormone levels and with quantitative scintiscanning.

RESULTS

A linear functional correlation was found between the peak flow velocities in the inferior thyroid artery and the fT3 or fT4 level. If the peak flow velocities were greater than 1.2 m/s, hyperthyroid metabolism prevailed, whereas at velocities below 0.3 m/s latent hypothyroidism was present.

CONCLUSION

These results show that Doppler sonography of the inferior thyroid artery can supply pointers (capable of being recorded) to the state of functioning of the thyroid even before knowing the laboratory parameters.

[Diagnosis and therapy of hypothyroidism in adulthood]

In the majority of cases, the symptoms of hypothyroidism develop slowly and as a result, they often are not recognized or misjudged for a long time. The complete picture is a late diagnosis. Especially in older patients, the symptoms are quite frequently assigned to the aging process. The most important form is the primary hypothyroidism often caused by auto-immune thyroiditis. The presence of a hypothyroidism should be considered more often and a TSH examination should be run. Normal TSH levels exclude a primary hypothyroidism. Increased TSH levels in conjunction with lowered T4 levels prove the diagnosis. If a secondary form is suspected, complete pituitary diagnostics are mandatory. The substitution therapy is carried out with a medium dosage of levothyroxine, 2.0 micrograms/kg body weight per day. The appropriate dosage should be established slowly using small initial dosages. This is especially important in older patients and in those suffering from coronary disorders. For younger patients and those with a shorter history, a more immediate adjustment is possible. During gravidity, the hormone requirement increasing by 40% must be taken into consideration. The therapeutic effect is shown by the clinic as well as by the TSH level. Overdosage will lead to a reversible appearance of thyreoitoxicosis factitia and require re-adjustment of the dosage. A physiological dosage does not have negative consequences on the bone metabolism. Transitory corrections are possible although a continuous substitution is necessary most of the time. Regular checks must be made as the therapy may be discontinued in 40% of the cases. In case of subclinical hypothyroidism, an indication for treatment does not exist in all patients. However, treatment is indicated if there is a high risk for developing a permanent form of hypothyroidism or if additional findings exist possibly linked to subclinical hypothyroidism. This would make a hormone substitution necessary. In case of doubt, a probatory therapy can be initiated and discontinued after 6-12 months when there is no therapeutic effect.

FNR-DNA interactions at natural and semi-synthetic promoters

Two rapid and convenient methods have been developed for the amplification and purification of FNR, the anaerobic transcription regulator of Escherichia coli. The overproduced proteins resemble wild-type FNR in their basic properties: oligomeric state, iron contents (up to 2.7 atoms per monomer), DNA-binding affinities and ability to activate transcription. However, unlike previous preparations, FNR could be isolated in a form containing up to 0.25 atoms of acid-labile sulphur per monomer. Incorporation of iron increased the Mr of FNR from 28,000 to 40,000. Under anaerobic conditions, reconstituted FNR exhibited absorption maxima at 315 nm and 420 nm, which were replaced by a broad absorbance from 380 to 440 nm under aerobic conditions. These observations indicate that FNR contains one redox-sensitive [3Fe 4S] or [4Fe 4S] centre per monomer. Footprints of FNR-dependent promoters (ansB, fdn, fnr, narG, pflP6, pflP7 and nirB) showed protection at all of the predicted FNR sites except the pflP7 (-57.5), ansB (-74.5) and nirB (-89.5) sites. An unpredicted second binding site was detected at -57.5 in the narG promoter. Hypersensitive sites within regions of FNR protection indicated that FNR bends DNA in a similar way to CRP. Promoters containing binding sites for FNR (FF), CRP (CC) or hybrid sites (CF or FC) were footprinted with FNR and two derivatives (FNR-610 and FNR-573) which activate the CCmelR promoter in vivo. FNR preferentially protected the FNR site (FF) whereas FNR-610 preferred CC and FNR-573 interacted with equal affinity at all sites.

Oxygen radicals do not play a role in arteriolar dilation during cortical spreading depression

This study examined the role of oxygen radicals in pial arteriolar changes during cortical spreading depression (CSD). CSD was induced by microinjection of 5% KCl in anesthetized adult rabbits. Pial diameter was measured with a closed cranial window and intravital microscopy. During control CSD (n = 12), the dilation amplitude and area were 55 +/- 14% and 693 +/- 69 mm2 (baseline = 76 +/- 14 microns), respectively. Oxygen radical scavengers, superoxide dismutase (SOD; 105 U/ml, topical application; n = 5) or oxypurinol (50 mg/kg i.v.; n = 7), did not alter the dilation amplitude and area or change onset latency during CSD. Further, SOD and oxypurinol did not prevent NG-nitro-L-arginine from attenuating arteriolar dilation during CSD (n = 12). We conclude that oxygen radicals do not play a role in the transient dilation of cerebral arterioles during CSD.

Ischemia reduces CGRP-induced cerebral vascular dilation in piglets

BACKGROUND AND PURPOSE

Effects of anoxic stress on cerebrovascular responses to calcitonin gene-related peptide (CGRP) have not been examined previously. We determined the effects of total global ischemia on cerebral arteriolar responses to CGRP in newborn pigs.

METHODS

Piglets were anesthetized and ventilated with a respirator. Pial arteriolar diameter was determined using a closed cranial window and intravital microscopy. Baseline arteriolar diameters ranged from 80 to 100 microns. Arteriolar responses to 10(-9) and 10(-8) mmol/L CGRP applied topically were determined before and 1, 2, and 4 hours after a 10-minute period of total global ischemia. Ischemia was caused by increasing intracranial pressure.

RESULTS

Before ischemia, CGRP dilated arterioles by 14 +/- 2% (n = 6) and 24 +/- 3% (n = 7) at 10(-9) and 10(-8) mmol/L, respectively. However, after ischemia, arteriolar responses to 10(-9) mmol/L CGRP were reduced at 1 hour to 4 +/- 1%, at 2 hours to 3 +/- 2%, and at 4 hours to 5 +/- 4% (P < .05 for all comparisons). Similarly, arteriolar responses to 10(-8) mmol/L CGRP were reduced to 5 +/- 2% at 1 hour, 5 +/- 2% at 2 hours, and 10 +/- 6% at 4 hours (P < .05 for all comparisons). In time control animals, arteriolar responses to CGRP did not change over time. In other animals, we examined effects of pretreatment with indomethacin (5 mg/kg IV) on ischemia-induced decreases in arteriolar responses to CGRP. Indomethacin administration did not preserve arteriolar dilation to CGRP at 1 hour after ischemia, but responses were normal at 2 hours.

CONCLUSIONS

Total global ischemia leads to prolonged attenuated dilator responses of cerebral arterioles to CGRP. In addition, indomethacin treatment alters effects of ischemia on CGRP-induced dilation.

[A study on model of inheritance of systemic lupus erythematosus in Chinese]

Analysis of segregation and heritability were performed, with the aid of Penrose's method, maximum likelihood estimation and Falconer's method, in 215 cases with systemic lupus erythematosus (SLE) and their pedigrees to explore its possible model of inheritance. Results showed that prevalence of SLE in first-degree relatives of the proband with SLE was 0.85% and higher than that in general population (0.03%). A ratio of s/q approached 1/square root q with Penrose's method, segregation proportion was equal to 0.029 with simple segregation analysis, with a chi-square for goodness-of-fit of 0.0001 (P > 0.05), and the heritability of SLE was 56.7% (P < 0.05). It suggests that SLE follows a pattern of multifactorial inheritance rather than single-gene one.

[Identification of streptavidin]

In this report, streptavidin (SA) was further identified on the basis of our previous researches in SA isolation and purification. 23.2 mg of SA productivity could be obtained after purification by DEAE-52 column from 1 L of culture supernatant. The spectrum scanning of ultraviolet absorption was congruent with that of the Sigma product. 2 bands appeared on the SDS-PAGE electrophoresis of SA. The molecular weight of SA was 72 881 Dalton with PI 6.0; the averaged biotin-binding activity was 18 micrograms/mg. The results confirmed that the methods of isolation and purification of SA developed by authors were reliable for immunological application.

Nitric oxide and prostaglandins interact to mediate arteriolar dilation during cortical spreading depression

We examined whether blockade of prostaglandin synthesis by indomethacin could attenuate the effect of nitric oxide synthase (NOS) inhibition on cerebral arteriolar dilation during cortical spreading depression (CSD). CSD was induced by microinjection of 5% (670 mM) KCl onto the cerebral cortex of anesthetized adult rabbits. A closed cranial window and intravital microscopy were used to measure pial arteriolar diameter, and NOS activity was determined by the conversion assay of [14C]arginine to [14C]citrulline. CSD dilated pial arterioles by 47 +/- 3% (baseline = 80-88 microns) (n = 21, P < 0.05), and inhibition of NOS by NG-nitro-L-arginine (L-NNA) (15 mg/kg iv) reduced dilation during CSD by over one-half (n = 8, P < 0.05) without altering the onset latency to CSD. After indomethacin administration (15 mg/kg iv), CSD dilated arterioles from 73 +/- 2 to 152 +/- 6 microns (n = 4, P < 0.05). However, after administration of both indomethacin and L-NNA (n = 5), CSD-induced arteriolar dilation was not different from the situation where indomethacin alone was given. Thus indomethacin completely abolished the inhibitory effect of L-NNA on CSD-induced dilation. Administration of L-NNA inhibited NOS activity in brain cortex almost completely (n = 8, P < 0.05), whereas indomethacin itself had no effect (n = 8). In addition, L-NNA inhibited topical acetylcholine (10(-5) M)-induced arteriolar dilation (n = 3, P < 0.05), and this effect was not altered by indomethacin (n = 4). In summary, L-NNA reduced arteriolar dilation during CSD. However, after administration of indomethacin, L-NNA does not reduce CSD-induced arteriolar dilation.

Glutamate-induced cerebral vasodilation is mediated by nitric oxide through N-methyl-D-aspartate receptors

BACKGROUND AND PURPOSE

It was found that glutamate, a major neurotransmitter, is vasoactive in the cerebral circulation. However, the mechanism is unclear. This study was designed to investigate the role of nitric oxide (NO) and N-methyl-D-aspartate (NMDA) receptors in cerebral arteriolar dilation to glutamate.

METHODS

Newborn, chloralose-anesthetized pigs were equipped with a closed cranial window. The diameter of pial arterioles was measured by means of intravital microscopy, and NO synthase (NOS) activity in brain cortex was determined by the conversion assay of [14C]arginine to [14C]citrulline.

RESULTS

Topical application of glutamate at 10(-7), 10(-6), and 10(-5) mol/L (n = 5) increased the mean diameter by 12 +/- 3%, 13 +/- 2%, and 18 +/- 3% (+/- SEM), respectively (baseline, 91 +/- 10 microns; P < .05). Similarly, NMDA application at the above doses (n = 5) dilated arterioles by 10 +/- 2%, 16 +/- 3%, and 18 +/- 6%, respectively (baseline, 97 +/- 4 microns; P < .05). Topical application of 10(-4) mol/L NG-nitro-L-arginine (L-NNA), which inhibited NOS activity by 93%, blocked the arteriolar dilation to glutamate or NMDA. Furthermore, administration of MK-801, a potent inhibitor of NMDA receptors, blocked glutamate-induced vasodilation completely in both topical application (10(-5) mol/L; n = 6) and intravenous administration (5 to 10 mg/kg; n = 5). In addition, neither L-NNA nor MK-801 attenuated the vasodilation to hypercapnia (PCO2 = 40 to 68 mm Hg).

CONCLUSIONS

Glutamate-induced cerebral arteriolar dilation is mediated by NO through NMDA receptors, and NO does not play a major role in the cerebral arteriolar dilation to hypercapnia (PCO2 = 40 to 68 mm Hg) in newborn pigs.

PDI-, PPI- and chaperone-catalyzed refolding of recombinant human IL-2 and GM-CSF

The studies on PDI-, PPI- and chaperone-catalyzed refolding of recombinant human IL-2 and GM-CSF show that PDI can prevent the mismatch of disulfide bonds and formation of aggregates by interchains linkage; furthermore, PDI can correct the mismatching of disulfide bonds in IL-2 isomers. PPI can increase the rate of folding reaction while chaperone can prevent the aggregation during the folding process. In addition, there is a synergistic effect between them.

[Culture of Streptomyces and purification of streptavidin]

For preparation and purification of Streptavidin, two synthetic mediums and a procedure for purifying Streptavidin were studied. We found that Streptomyces avidinii grew vigorously and showed typical colony characterization. At the sametime, these synthetic mediums were in favour of producing Streptavidin with a maximal production of 15.2 micrograms/ml by using DEAE 52 column for purification of Streptavidin. This purification procedure is very simple and easy, and could be widely used.

Nitric oxide promotes arteriolar dilation during cortical spreading depression in rabbits

BACKGROUND AND PURPOSE

Pial arterioles transiently dilate during cortical spreading depression (CSD), although the mechanisms are unclear. We tested the hypothesis that increased production of nitric oxide (NO) promotes arteriolar dilation.

METHODS

Urethane-anesthetized rabbits were equipped with cranial windows, and the diameter (reported in micrometers) of a pial arteriole was determined via intravital microscopy. In each rabbit, a baseline CSD was elicited by microapplication of KCl onto the cortex, and resultant pial arteriolar dilation was measured. Either 100 mumol/L N omega-nitro-L-arginine methyl ester (L-NAME) or 50 mumol/L NG-nitro-L-arginine (L-NA), both competitive NO synthase inhibitors, was then applied to the brain surface. A CSD was elicited as before. The L-NAME and L-NA were then removed by artificial cerebrospinal fluid washes. An additional CSD was induced with KCl as before.

RESULTS

Control CSD in the L-NAME group dilated pial arterioles; baseline diameter, 66 +/- 7 mm, with CSD = 106 +/- 8 mm (59% increase). After topically applied L-NAME, CSD dilated pial arterioles less: baseline diameter, 61 +/- 7 mm, with CSD = 77 +/- 6 mm (26% increase), P < .05 compared with control CSD diameter. Topical L-NA had similar effects on CSD: control CSD dilated pial arterioles 51%; after topical L-NA, only 14% (P < .05). After removal of L-NAME or L-NA, CSD-induced pial arteriolar dilation was similar to original control values.

CONCLUSIONS

The reversible inhibition of CSD-induced pial arteriolar dilation by either L-NAME or L-NA suggests that NO contributes to arteriolar dilation observed with CSD.

Nerve growth factor in different crystal forms displays structural flexibility and reveals zinc binding sites

Murine beta-nerve growth factor (beta NGF) is a 118 amino acid residue polypeptide which, as a functional dimer, plays an important role in the survival and development of certain neuronal populations. The structure of the bis-desocta1-8 form of murine beta NGF has been determined in two different crystal modifications using X-ray methods. The two crystal forms, with space groups P2(1)2(1)2(1) and C2, were grown from 18 to 20% polyethylene glycol 8000 and 100 mM Pipes (pH 6.1) with zinc acetate concentrations of 1 mM and 100 mM, respectively. The C2 structure was solved by multiple isomorphous replacement using four heavy-atom derivatives and was refined to a crystallographic residual of 17.9% and 2.5 A resolution. The crystals contain three beta NGF monomers per asymmetric unit. Two monomers form a dimer related by a non-crystallographic 2-fold axis of symmetry. The third monomer also forms a dimer that is very similar, but with a crystallography related monomer as a partner. The electron density clearly defines residues 12 through 115 for all three monomers but the extreme N and C-terminal residues (9 to 11, 116 to 118) are ill defined in some cases. The P2(1)2(1)2(1) structure was solved by molecular replacement using the C2 structure as a search model and was refined to a crystallographic residual of 19.7% at 2.8 A resolution. This crystal form contains two monomers per asymmetric unit, again arranged as a non-crystallographic 2-fold-related dimer. The N and c termini are also variably defined. The core of each of the five monomers, which forms a cysteine knot motif, is very similar in all structures. Also, the dimer structures are very similar to one another, whether the monomers are related by crystallographic or non-crystallographic symmetry. However, three of the four loop regions that extend from the core of each monomer display substantial variability in conformation, even between monomers of the same dimer. This structural variability in the putative receptor binding regions suggests that structural malleability might be important in allowing the ligands to bind to different receptors with different affinities.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunohistochemical characterization of monoclonal antibodies directed against the TSH receptor

Monoclonal antibodies have been obtained by fusing mouse myeloma cells with spleen cells of mice immunized with crude thyroid membranes. Among the antibodies reactive with different thyroid antigenic components, three were found to specifically react with TSH receptor molecules. These antibodies displayed characteristic staining patterns on frozen sections of thyroid tissue from patients with various thyroid diseases upon identification of antibody binding by indirect peroxidase staining. No specific reactivity was detected with tissue from other human organs, such as pancreas, liver, fat, and muscle. The results demonstrate that the immunoperoxidase technique and the specificity of the monoclonal antibodies produced permitted the identification of cellular constituents that might be important antigens in autoimmune thyroid disease.

Calcitonin gene-related peptide promotes cerebrovascular dilation during cortical spreading depression in rabbits

We examined the role of calcitonin gene-related peptide (CGRP) in cortical spreading depression (CSD)-induced dilation of rabbit pial arterioles. In urethan-anesthetized rabbits instrumented with a closed cranial window, CSD induction with KCl dilated pial arterioles from 86 +/- 10 to 132 +/- 13 (mean +/- SE, n = 6) microns (a 54 +/- 9% increase). Topical administration of 12.8 microM CGRP-(8-37), a competitive inhibitor of the CGRP receptor, reduced CSD-induced pial dilation from 54 +/- 9% baseline to 33 +/- 9% (P < 0.05). Removal of the receptor antagonist from the brain surface restored CSD-induced dilation to 59 +/- 11% (P < 0.05, compared with the response with the antagonist present). In other animals, we showed that this dose of the CGRP antagonist attenuated arteriolar dilation to topically applied 10(-7) M CGRP (n = 5), but it did not alter arteriolar dilation to arterial hypercapnia. We also evaluated the dilator potency of substance P (SP) compared with CGRP. Dilation with 10(-7) M SP was only 22 +/- 11%, whereas arterioles dilated to 57 +/- 7% above baseline diameter with 10(-7) M CGRP. We conclude that CGRP contributes to the transient arteriolar dilation that is characteristic of CSD.

Comparative effects of angiotensin-(1-7) and angiotensin II on piglet pial arterioles

BACKGROUND AND PURPOSE

Recent investigations indicated that degradation fragments of angiotensins could be involved in the regulation of the cerebral circulation and that their effects might be mediated by prostaglandins. The present study was designed to examine the effect of angiotensin-(1-7), a major endogenous heptapeptide fragment, on cerebral arteriolar diameter and compare it with the octapeptide angiotensin II, and further to determine whether prostaglandins mediate their effects.

METHODS

Newborn, anesthetized pigs were equipped with a closed cranial window, and the diameter of one pial arteriole was measured using intravital microscopy.

RESULTS

Topical application of angiotensin-(1-7) (n = 9) increased the diameter by 6.8 +/- 5.3% (mean +/- SEM), 10.4 +/- 5.2%, 14.3 +/- 5.9%, and 17.5 +/- 7.7% (P < .05) at 10(-7), 10(-6), 10(-5), and 10(-4) mol/L, respectively (baseline, 94 +/- 3 microns). Topical application of angiotensin II (n = 8) increased the diameter by 9.6 +/- 7.0%, 9.6 +/- 7.6%, 11.3 +/- 8.4% (P < .05), and 5.5 +/- 7.9% at 10(-7), 10(-6), 10(-5), and 10(-4) mol/L, respectively (baseline, 94 +/- 5 microns). After administration of indomethacin (5 mg/kg IV), which did not significantly change the baseline arteriolar diameter, neither angiotensin-(1-7) at 10(-4) mol/L nor angiotensin II at 10(-5) mol/L caused significant vasodilation.

CONCLUSIONS

The results indicate that angiotensin-(1-7) is a modest dilator in the cerebral circulation, as is angiotensin II, and that prostaglandins may mediate responses.

Retention of cerebrovascular dilation after cortical spreading depression in anesthetized rabbits

BACKGROUND AND PURPOSE

We examined responses of rabbit pial arterioles to three different stimuli before and after induction of cortical spreading depression.

METHODS

In urethane-anesthetized rabbits equipped with a closed cranial window, we measured pial arteriolar diameter during baseline conditions, topical application of calcitonin gene-related peptide (CGRP), topical application of acetylcholine, and inhalation of 10% CO2 in air (arterial hypercapnia) before cortical spreading depression and 30, 60, and 120 minutes after cortical spreading depression. Cortical spreading depression was induced by localized application of a 5% KCl solution anterior to the arteriole being measured.

RESULTS

Average baseline diameter was approximately 90 microns. During cortical spreading depression, arteriolar diameter increased to a peak value that was 50 +/- 4% above baseline (n = 32). Before cortical spreading depression, arteriolar diameter changed 47 +/- 7% (n = 9) during hypercapnia, 17 +/- 3% (n = 4) during 10(-9) mol/L CGRP, 42 +/- 10% (n = 7) during 10(-7) mol/L CGRP, 29 +/- 6% (n = 4) during 10(-6) mol/L acetylcholine, and 61 +/- 13% (n = 6) during 10(-4) mol/L acetylcholine. Arteriolar responsiveness to any of these stimuli was not changed significantly by prior cortical spreading depression.

CONCLUSIONS

Dilator capacity of pial arterioles is still intact in urethane-anesthetized rabbits after cortical spreading depression.