Photorefractive properties of Cu-doped KNSBN crystal with fluorine replacing oxygen

We report the photorefractive properties of a new kind of Cu-doped KNSBN crystal in which a small fraction of oxygen (O) atoms are replaced with fluorine (F) atoms. The replacement of oxygen with fluorine in Cu:KNSBN crystals leads to a much shorter response time of 30 ms at an incident intensity of 5 W/cm(2). We also discuss the effect of electron-hole competition on the coupling constant.

Complementation of the Arabidopsis pds1 mutation with the gene encoding p-hydroxyphenylpyruvate dioxygenase

Plastoquinone and tocopherols are the two major quinone compounds in higher plant chloroplasts and are synthesized by a common pathway. In previous studies we characterized two loci in Arabidopsis defining key steps of this biosynthetic pathway. Mutation of the PDS1 locus disrupts the activity of p-hydroxyphenylpyruvate dioxygenase (HPPDase), the first committed step in the synthesis of both plastoquinone and tocopherols in plants. Although plants homozygous for the pds1 mutation could be rescued by growth in the presence of homogentisic acid, the product of HPPDase, we were unable to determine if the mutation directly or indirectly disrupted HPPDase activity. This paper reports the isolation of a cDNA, pHPPD, encoding Arabidopsis HPPDase and its functional characterization by expression in both plants and Escherichia coli. pHPPD encodes a 50-kD polypeptide with homology to previously identified HPPDases, including 37 highly conserved amino acid residues clustered in the carboxyl region of the protein. Expression of pHPPD in E. coli catalyzes the accumulation of homogentisic acid, indicating that it encodes a functional HPPDase enzyme. Mapping of pHPPD and co-segregation analysis of the pds1 mutation and the HPPD gene indicate tight linkage. Constitutive expression of pHPPD in a pds1 mutant background complements this mutation. Finally, comparison of the HPPD genomic sequences from wild type and pds1 identified a 17-bp deletion in the pds1 allele that results in deletion of the carboxyterminal 26 amino acids of the HPPDase protein. Together, these data conclusively demonstrate that pds1 is a mutation in the HPPDase structural gene.

[Changes in cerebral circulation function during head down bed rest for 7 days]

To further understand the effects and regulation of brain circulation before, during and after short-term -6 degrees head down bed rest (HDT), 6 healthy young men aged 19-21 years, were subjected to HDT for 7 d. Cerebral blood flow velocity in the middle cerebral arteries of both sides was measured with a TC2000TCD instrument in 6 young adults before, during, and after 7d HDT. The results showed that cerebral blood flow velocity in the middle cerebral arteries increased throughout HDT, the increase was obvious in 24 h. They reached the highest value at the 4th hour and the lowest value on the 5 th day, and then, there were a tendency to rise on the 6th day and 7th day. The changes were about the same on both sides.

Association of apolipoprotein E polymorphism and concentration with serum lipids and apolipoprotein level in the Chinese from Shanghai

The influence of apolipoprotein E polymorphism and apoE level on serum lipids and apolipoproteins was investigated in 71 healthy people and 43 patients with coronary artery disease from Shanghai. The frequency of apoE alleles was 0.06 for epsilon2, 0.86 for epsilon3, and 0.07 for epsilon4 in the healthy group, and 0.14 for epsilon2, 0.77 for epsilon3, and 0.09 for epsilon4 in the coronary artery disease group. There was no significant difference in the frequency of apoE alleles between these two groups. Serum levels of triglyceride and apo AI did not differ according to apoE genotypes, whereas serum level of apoB was significantly different according to apoE genotypes (p<0.05) both in healthy and coronary artery disease groups. However, in the healthy group, apo epsilon2 allele carriers had significantly higher level of apoE than apo epsilon3 and epsilon4 allele carriers (p<0.001) and apo epsilon4 allele carriers had significantly higher level of total cholesterol than apo epsilon3 and epsilon2 allele carriers. These were not observed in the coronary artery disease group. ApoE concentration was positively correlated with cholesterol, apoAI, and apoB levels in the control subjects and no significant correlation was observed with triglyceride level. In contrast, apoE level was positively related only to triglyceride level in the coronary artery disease group. In the control group, apoE genotypes and apoE level explained together 19.3% and 26.6% of the variability of apoB and cholesterol level, respectively, apoE polymorphism explained 23% of the variability of apoE level and apoE level explained 13.2% of the variability of apoAI level. In the coronary artery disease group, only apoE level explained 41.7% of triglyceride variability. Finally we compared our results with those previously obtained in a French healthy population, the Stanislas cohort. Results suggested that there were some difference between the Chinese control and the French subjects.

[Relationship between sleep apnea and cerebral blood flow]

OBJECTIVE

To study the cerebral blood flow in patients with and without sleep apnea syndrome (SAS).

METHOD

Thirty patients with SAS were studied, with 32 patients without SAS as controls. The age, sex and baseline diseases were comparable between these two groups. Subjects were studied by polysomnography and transcranial Doppler ultrasonography. The systolic (VS) and mean (VM) cerebral blood flow velocities, resistent index (RI), and frequency spectral shape were determined. Anterior, middle and posterior cerebral arteries were examined by transcranial Doppler ultrasonography in all patients.

RESULT

VS and VM were significantly lower in patients with SAS than those in the control subjects (P < 0.05 and P < 0.01). RI of the right PCA in SAS patients (0.56 +/- 0.06) was significantly higher than that in the controls (0.48 +/- 0.09, P < 0.05). Changes in the cerebral blood flow frequency spectral shape were remarkably increased in the SAS group as compared to control group. VS and VM were negatively correlated with apnea index (r = -0.413 and -0.628, P < 0.05 and 0.01), but positively correlated with SaO2(r = 0.435 and 0.712, P < 0.05 and 0.01).

CONCLUSION

The results suggest that SAS patients have decreased cerebral blood flow velocities and more frequency shape abnormalities. These may decrease cerebral perfusions, and lead to cerebral atherosclerosis and stroke.

[Correction of cardiac defects through a right minithoracotomy in children]

OBJECTIVE

To review the experience of correction of congenital cardiac defects through a right minithoracotomy.

METHOD

319 patients underwent correction of congenital heart malformations through right lateral thoracotomy under cardiopulmonary bypass. The average age was 3.44 +/- 1.59 years (range, 5 months-8 years). The average body weight was 13.66 - 3.98 kg (range, 6 - 26 kg). Cardiac defects repaired included atrial septal defect in 87 patients (1 patient associated with left superior vena cava (LSVC), 6 pulmonary stenosis, 5 partial anomalous pulmonary venous connection), ventricular septal defect in 200 (7 patients with coexisting patent ductus arteriosus, 7 mitral insufficiency, 3 LSVC, 11 right ventricular outflow tract obstruction), Fallot's Tetralogy in 19 (3 patients associated with LSVC, 1 single coronary malformation), partial endocardial cushion defect in 2 and other defects in 11. The mean cardiopulmonary bypass time was 56.07 +/- 24.90 min (range, 20 - 176 min) and the mean aortic crossclamping time was 32.97 +/- 20.38 min (range, 6 - 140 min). The average mechanical ventilation time after operation was 18.75 +/- 24.57 hr (range, 2 - 140.72 hr), and the mean postoperative hospital stay was 7.08 +/- 0.69 days (range, 7 - 17 days).

RESULT

No operative mortality and severe postoperative complications were noted.

CONCLUSION

The right lateral thoracotomy is a safe and effective alternative to a median sternotomy for correction of cardiac defects. Advantages of this approach include less injury, maintaining the continuity and the integrity of the bony thorax, and preventing postoperative pigeon breast. The cosmetic result is superior to that of median sternotomy or bilateral submammary incision.

Characterization of carbohydrates using a combination of derivatization, high-performance liquid chromatography and mass spectrometry

A combination of derivatization methods, chromatographic techniques and mass spectrometric ionization modes have been explored for the characterization of small sugars and medium-size oligosaccharides. Derivatization using 1-phenyl-3-methyl-5-pyrazolone (PMP) was preferred over pyridylamination (PA) owing to the simplicity of the reaction method, and also to enhanced ionization efficiency of the PMP derivatives relative to aminopyridyl sugars. The good quality and ease of separation of PMP derivatives by high-performance liquid chromatography were also advantages of using PMP derivatization rather than pyridylamination. PMP- and PA-monosaccharides produced abundant ions by either fast atom bombardment (FAB), electrospray ionization (ESI) or matrix-assisted laser desorption/ionization (MALDI). The PA and PMP derivatives of lactose, fucosyllactose and sialyllactose yielded FAB spectra with low S/N ratios, whereas ESI and MALDI produced better spectra with a hundredth of the material used for FAB. In general, PMP derivatives of these di- and trisaccharides gave rise to stronger signals than PA analogs. For Oligosaccharides containing more than three sugar rings, only PMP was used for derivatization, FAB was dropped and only ESI and MALDI were utilized.

Application of free-flow electrophoresis to the purification of trichosanthin from a crude product of acetone fractional precipitation

The application of free-flow electrophoresis (FFE) to the purification of trichosanthin (TCS) from a crude product of acetone fractional precipitation was investigated. An electrophoresis technique, combining field step electrophoresis (FSE) and zone electrophoresis (ZE) to a one-step procedure, was optimized until a satisfactory purification factor (1.35), high resolution, and purity (>99%) were achieved. Testing several separation buffer systems revealed that a throughput of 14.2 mg/h can be obtained when the very basic TCS (pI 10.1) was dissolved and electrophoresed in a phosphate buffer system of pH 4. The purity of electrophoresed trichosanthin was proved by a variety of analytical methods, such as sodium dodecyl sulfate (SDS)-gel electrophoresis, capillary isoelectric focusing (CIEF), and sequencing of N- and C-termini. The high purity and large throughput achieved at low cost by using FFE indicates that this method can be employed for TCS purification.

[Effect of 7 d head down bed rest on cardiopulmonary circulation in human]

Changes of cardiopulmonary circulation in 6 healthy young men during 7 d head down bed rest (-6 degrees HDT) were observed with the XXH-2000 lesser circulation and cardiac function instrument. Decrease of Q-j and Q-j/j-z, increase of hz, hc, and hc/hz were found during the initial 24 h. After 24 h, j-z decreased and Q-j/j-z increased. The results showed that increased pulmonary arterial pressure, increased preload of left and right heart, increased right myocardial contractility and congestion of the lungs appeared during 24 h bed rest, after which right myocardial contractility decreased. It suggests that the lesser circulation and cardiac function testing is a sensitive method for evaluating the cardiopulmonary circulation function during HDT.

Sp1, but not Sp3, functions to mediate promoter activation by TGF-beta through canonical Sp1 binding sites

Transforming growth factor beta (TGF-beta) causes growth arrest at the G1 phase of the cell cycle in most cell types. Both the cyclin dependent kinase inhibitor p15(INK4B) and p21(Cip1/WAF1) genes have been found to be induced by TGF-beta in human keratinocyte HaCaT cells. Analyses of the human p15 and p21 promoters have led to the identification of GC-rich sequences capable of binding to Sp1 transcription factors as necessary elements for the TGF-beta induction of both promoters. We report here that canonical Sp1 binding sites derived from the SV40 21 bp repeat could also support promoter induction by TGF-beta when placed upstream of a minimal luciferase reporter construct containing only the TATA and Inr elements. Gel retardation assays identified Sp1, Sp3 and DeltaSp3 as major factors binding to the canonical Sp1 sites in HaCaT cells and that TGF-beta treatment did not change their binding activities over a 24 h period. More importantly, GAL4-Sp1, but not GAL4-Sp3, chimeric protein supported TGF-beta mediated gene induction from a luciferase reporter construct driven by five GAL4 DNA binding sites. Our results suggest that Sp1 binding site can function as a distinct TGF-beta responsive element for TGF-beta mediated promoter expression and Sp1 per se can mediate this response.

[Preparation of monoclonal antibodies against hepatitis E and its application]

OBJECTIVE

To study the particle of hepatitis E virus (HEV) and its significance in specific diagnosis for hepatitis E (HE).

METHODS

Four strains of monoclonal antibodies (McAb) against HEV, 5B12, 5F1, 5B9 and 4G10, were prepared with HEV antigen (used as immunogen) expressed by genetic engineering and detected by indirect enzyme-linked immunosorbent assay (ELISA) with purified synthetic polypeptide antigen.

RESULTS

The monoclonal anti-HEV prefared could produce inhibitory reaction with anti-HEV positive serum and combined specifically with HEV particle forming virus-antibody complex seen clearly under electron microscope.

CONCLUSION

McAb against HEV so prepared with high specificity can be used to detect and identify HEV.

Dynamic study of nitric oxide and endothelin-1 during endotoxin shock and effects of their antagonists on hemodynamics

OBJECTIVE

To examine the relationship between the profound hypotension in endotoxic shock and the dynamic changes of nitric oxide (NO) and endothelin-1 (ET-1), so as to figure out which of the NO or ET-1 was more involved in the pathogenesis of endotoxic shock. And to investigate whether an offset of their opposite vasoactive effects would occur during endotoxic shock.

METHODS

24 rabbits were anesthetized and instrumented for recording hemodynamics. Endotoxin (E. coli 026: B6, 600 micrograms/kg) was bolus injected intravenously and the animals were randomly divided into four groups. Group I was control without any more intervention, and Group II, III, IV received bolus injections of L-NMA (10 mg/kg), phosphoramidon (2 mg/kg) or dexamethasone (2 mg/kg) respectively at 30 min post-endotoxin. Plasma NO3-, ET-1 and hemodynamics were measured at regular intervals. Their relationships were compared and analysed.

RESULTS

Plasma ET-1 achieved its peak level at 60 min post-endotoxin, and then waned. Plasma NO3- started rising at 120 min post-endotoxin, then progressive increase continued till the last measurement at 180 min post-endotoxin. The decrease of blood pressure was significant at about 120 min post-endotoxin and further went down until death. The changes of hemodynamics and NO showed a quite close temporal correspondence between the increase of NO and the decrease of blood pressure. L-NMA and phosphoramidon obviously reduced the plasma levels of NO and ET-1 to below their respective baseline levels, and showed transient effect of increase on blood pressure. Soon afterwards, however, the status of hemodynamics was aggravated. Dexamethasone just inhibited the excessive increase of NO and ET-1 during endotoxic shock without interfering their baseline levels and showed most beneficial effects on hemodynamics.

CONCLUSIONS

Both NO and ET-1 increase during endotoxic shock, but only the increase of NO has a close temporal correspondence with the decrease of blood pressure. It suggests a more important role of NO in pathogenesis of endotoxic shock. The increase of NO and ET-1 is different in time-process, which indicates that an offset of their opposite vasoactive effects would not occur. Intreference against the increase of NO and ET-1 during endotoxic shock is most beneficial when their baseline levels are maintained.

Comparative effects of losartan and captopril on ventricular remodeling and function after myocardial infarction in the rat

OBJECTIVE

To determine the effects of losartan and captopril treatment on ventricular remodeling and function after myocardial infarction in rats.

METHODS

Thirty-two rats with MI induced by coronary ligation after seven days were divided into four groups randomly and treated with captopril(2 g.liter-1, group A), losartan(10 mg.kg-1.d-1, group B), losartan(30 mg.kg-1.d-1, group C) and placebo (no drug, group D) for six weeks, respectively. Sham-operated rats(group E) served as controls. Echocardiography was performed at 1 and 7 weeks after MI, respectively.

RESULTS

Compared with the results before treatment, both LV end-diastolic internal diameter and volume decreased significantly and the thickened posterior wall was reversed in group A, B and C; the peak early filling velocity decreased whereas the peak velocity was increased in these three groups. There are no significant difference among the three treated groups. However, LV end-diastolic internal diameter and the E/A were still increased, whereas the thickness of anterior wall and the peak velocity of LV outflow were decreased in group A, B, and C after treatment comparing with group E.

CONCLUSION

Both angiotensin converting enzyme inhibitor and angiotensin II receptor antagonist can prevent the ventricular remodeling and improve the ventricular function.

Regulation of T cell immunity and tolerance in vivo by CD4

Previous experiments showed that peptides corresponding to a major CD4-binding site on the beta2 domain of MHC class II molecules, IAbeta134-148, enhance responses by CD4+ T lymphocytes to antigen, allo-antigen and bacterial superantigen in vitro, and to soluble protein in vivo. To determine whether peptide IAbeta134-148 acted by inhibiting antigen-induced T cell tolerance, ovalbumin-specific CD4+ lymph node (LN) T cells from TCR transgenic DO.11.10 mice were adoptively transferred into H-2 syngeneic BALB/c recipients. Tolerance was then induced by injecting antigen i.v. When peptide IAbeta134-148 was used to interfere with CD4-MHC class II interactions, accumulation of clonotype-positive T lymphocytes in the LN and induction of T cell tolerance in vivo were delayed. The mechanism by which peptide IAbeta134-148 inhibited T cell tolerance included the peptide's ability to block activation-induced cell death. Further, antigen-specific splenic T lymphocytes were not tolerized in IAbeta134-148-treated mice, providing a reservoir of T cells that could respond to a secondary immunization. The results reported here suggest that participation of the T cell co-receptor, CD4, in TCR signaling differentially affected both T cell migration and the induction of antigen-specific tolerance. Therefore, in this in vivo model system, the combined strength of all signals received (e.g. via TCR, co-receptors and co-stimulators) determined whether T cell immunity or apoptosis and tolerance resulted from antigenic stimulation. These findings are potentially important for the development of reagents to enhance vaccine efficacy and tumor immunity.

Promotion of follicular antrum formation by pig oocytes in vitro

Pig oocyte-cumulus-granulosa cell complexes (OCG complexes) from pig early antral follicles reorganise an antrum under the stimulation of FSH. The purpose of this study was to examine the role of the oocytes in antrum formation. In the first experiment, oocyte-cumulus complexes were removed from pig OCG complexes, and the antrum formation of parietal granulosa cells themselves (PGs) was examined. Antrum formation by sham-operated OCG complexes (OC/G complexes), in which the connections between the oocytes-cumulus complexes and the parietal granulosa cells had been disrupted, was also examined. The complexes were cultured for 8 days in collagen gels in the presence of 10 ng/ml FSH. Antra were formed in about 60% of the intact OCG complexes and the sham-operated OCG complexes, while only 20% of the PGs formed antra. In the second experiment, oocyte-cumulus complexes in the OCG complexes were replaced by denuded oocytes (O/G complexes) or Sephadex G-25 beads (B/G complexes) similar in diameter to the oocytes, and the two types of complexes were cultured under the same conditions. The O/G complexes formed antra to a similar extent as the OC/G complexes, whereas the B/G complexes scarcely formed any antra. The histological sections showed that the granulosa cells in the OC/G and O/G complexes were in intimate contact with each other and retained a shape similar to those in the ovarian follicles, while the granulosa cells in the PGs and B/G complexes became quite irregular in shape. These results suggest that pig oocytes promote contact between the granulosa cells to induce antrum formation in a physiological manner.

[Effects of tea polyphenol on blood lipid and antioxidation in vivo in aged rats]

OBJECTIVE

To study the ability of tea polyphenol to lowering blood lipid and antioxidation in the aged rats.

METHODS

The SD rats were divided into three groups, i.e., control group and two trial groups fed with 1% and 2% tea polyphenol for six weeks, respectively.

RESULTS

Tea polyphenol could reduce serum level of lipid peroxide and increase the ratio of high-density lipoprotein cholesterol (HDL-C) to total cholesterol (TC), and significantly lower serum level of lipid peroxide in rats. Activities of superoxide dismutase in red blood cells of rats fed with 2% tea polyphenol were significantly higher than those in control ones.

CONCLUSION

Tea polyphenol can enhance antioxidation in vivo in the aged rats.

Transforming growth factor beta stimulates the human immunodeficiency virus 1 enhancer and requires NF-kappaB activity

Transforming growth factor beta (TGF-beta) is the prototype of a large superfamily of signaling molecules involved in the regulation of cell growth and differentiation. In certain patients infected with human immunodeficiency virus type 1 (HIV-1), increased levels of TGF-beta promoted the production of virus and also impaired the host immune system. In an effort to understand the signaling events linking TGF-beta action and HIV production, we show here that TGF-beta can stimulate transcription from the HIV-1 long terminal repeat (LTR) promoter through NF-kappaB binding sites in both HaCaT and 300.19 pre-B cells. When introduced into a minimal promoter, NF-kappaB binding sites supported nearly 30-fold activation from the luciferase reporter upon TGF-beta treatment. Electrophoretic mobility shift assay indicated that a major factor binding to the NF-kappaB site is the p50-p65 heterodimeric NF-kappaB in HaCaT cells. Coexpression of Gal4-p65 chimeric proteins supported TGF-beta ligand-dependent gene expression from a luciferase reporter gene driven by Gal4 DNA binding sites. NF-kappaB activity present in HaCaT cells was not affected by TGF-beta treatment as judged by the unchanged DNA binding activity and concentrations of p50 and p65 proteins. Consistently, steady-state levels of IkappaB alpha and IkappaB beta proteins were not changed by TGF-beta treatment. Our results demonstrate that TGF-beta is able to stimulate transcription from the HIV-1 LTR promoter by activating NF-kappaB through a mechanism distinct from the classic NF-kappaB activation mechanism involving the degradation of IkappaB proteins.

Molecular cloning and characterization of lustrin A, a matrix protein from shell and pearl nacre of Haliotis rufescens

A specialized extracellular matrix of proteins and polysaccharides controls the morphology and packing of calcium carbonate crystals and becomes occluded within the mineralized composite during formation of the molluscan shell and pearl. We have cloned and characterized the cDNA coding for Lustrin A, a newly described matrix protein from the nacreous layer of the shell and pearl produced by the abalone, Haliotis rufescens, a marine gastropod mollusc. The full-length cDNA is 4,439 base pairs (bp) long and contains an open reading frame coding for 1,428 amino acids. The deduced amino acid sequence reveals a highly modular structure with a high proportion of Ser (16%), Pro (14%), Gly (13%), and Cys (9%). The protein contains ten highly conserved cysteine-rich domains interspersed by eight proline-rich domains; a glycine- and serine-rich domain lies between the two cysteine-rich domains nearest the C terminus, and these are followed by a basic domain and a C-terminal domain that is highly similar to known protease inhibitors. The glycine- and serine-rich domain and at least one of the proline-rich domains show sequence similarity to proteins of two extracellular matrix superfamilies (one of which also is involved in the mineralized matrixes of bone, dentin, and avian eggshell). The arrangement of alternating cysteine-rich domains and proline-rich domains is strikingly similar to that found in frustulins, the proteins that are integral to the silicified cell wall of diatoms. Its modular structure suggests that Lustrin A is a multifunctional protein, whereas the occurrence of related sequences suggest it is a member of a multiprotein family.

[DNA polymorphism in the genomes of different Escherichia coli strains]

Bacteria have been traditionally classified on the basis of their morphology, biochemical reaction, serology and etc. However, in some case these methods could not authenticate the closely related bacteria strains. In this study, we cloned two repetitive DNA sequences with 0.9 and 0.6 kb in length from Escherichia coli K12 strain JM109 and designated as ECR-1 and ECR-6 respectively. Using ECR-1 and ECR-6 sequences or their combination as the probes for DNA polymorphism analysis, we were be able to develop a molecular method of biotyping for the identification of very closely related strains of Escherichia coli. Both of ECR-1 and ECR-6 probes could be applied for the taxonomy, epidemiological and microecological studies, and clinical diagnosis for pathogenic Escherichia coli strains.

Effects of Chinese herb medicine on improving the circulation of rabbits under simulated weightlessness

In order to find out the effects of Chinese herb medicine on improving the functional state of blood circulation under weightlessness (WL) or simulated weightlessness (SWL), five experiments (building the SWL animal model and determining the treatment based on the differentiation of symptoms and signs, selecting herb medicine, determining the dosage of Chinese herb medicine, pharmacological text and toxicological experiment of (DH) were accomplished. Two kinds of Chinese herb medicine(CQ and DH) having the effects of improving the circulatory conditions of rabbits in SWL were selected. SWL animal model, space blood stasis and mechanism and effects of Chinese herb medicine were discussed.

Effects of additional iron-chelators on Fe(2+)-initiated lipid peroxidation: evidence to support the Fe2+ ... Fe3+ complex as the initiator

The addition of chelated Fe2+ ions in a liposomal system often results in a short lag period before peroxidation starts. The addition of a second chelator at the end of the lag period results in an inhibition of the lipid peroxidation. The degree of inhibition depends on the stability constants of the chelator in ligating Fe2+ and/or Fe3+. A more striking inhibitory effect was observed for the chelators with higher stability constant for either or both Fe(2+)- and Fe(3+)-complex, but much less inhibition was found for those with lower stability constants for both complexes. Assuming that the "initiator" for iron-dependent lipid peroxidation is formed through the redox process of iron ion and finally emerged at the end of the latent period, the inhibitory effect of the second chelator may be explained as the abstraction of either Fe2+ or Fe3+ from the initiator by an additional free chelator, which results in the decomposition of the initiator. This study supports the hypothesis that a Fe2+ ... Fe3+ complex is responsible for iron-initiated lipid peroxidation.

Effect of tidal volume and frequency on airway responsiveness in mechanically ventilated rabbits

We evaluated the effects of the rate and volume of tidal ventilation on airway resistance (Raw) during intravenous methacholine (MCh) challenge in mechanically ventilated rabbits. Five rabbits were challenged at tidal volumes of 5, 10, and 20 ml/kg at a frequency of 15 breaths/min and also under static conditions (0 ml/kg tidal volume). Four rabbits were subjected to MCh challenge at frequencies of 6 and 30 breaths/min with a tidal volume of 10 ml/kg and also under static conditions. In both groups, the increase in Raw with MCh challenge was significantly greater under static conditions than during tidal ventilation at any frequency or volume. Increases in the volume or frequency of tidal ventilation resulted in significant decreases in Raw in response to MCh. We conclude that tidal breathing suppresses airway responsiveness in rabbits in vivo. The suppression of narrowing in response to MCh increases as the magnitude of the volume or the frequency of the tidal oscillations is increased. Our findings suggest that the effect of lung volume changes on airway responsiveness in vivo is primarily related to the stretch of airway smooth muscle.

[Changes of microcirculation in nasal mucosa during -15 degrees head-down tilt]

Changes of microcirculation in nasal mucosa in 19 young men during 2.5 h head-down -15 degrees tilt (DHT) were observed with Laser Doppler Flowmetry. The results showed that the change of microcirculation in nasal mucosa was significant, blood volume, concentration and the velocity of blood flow increased, and distinct periodical wave of microvessels appeared during HDT. The results suggest that the change of microcirculation in nasal mucosa caused by fluid shift from the lower to the upper body is one of the important factors causing stuffy nose and breathe with a little difficulty.

Erythrocyte deformation in simulated weightless human and rabbits

Effect and mechanism of simulated weightlessness (SWL) in humans and rabbits erythrocyte deformation were studied. Erythrocyte deformation and membrane fluidity in humans and rabbits, and erythrocyte morphology and hemorreology indices in control and HDT rabbits were measured. The results were a decrease in erythrocyte deformation and membrane fluidity in humans and rabbits during SWL, a significant increase in abnormal erythrocyte, blood viscosity, hematocrit, fibrinogen, and red blood cell aggregation index in HDT rabbits. These results show that the changes in erythrocyte shape, increase of erythrocyte internal viscosity and changes in erythrocyte visco-elasticity may be causing the decrease of erythrocyte deformation in SWL humans and rabbits.

Mechanisms for the mechanical response of airway smooth muscle to length oscillation

Airway smooth muscle tone in vitro is profoundly affected by oscillations in muscle length, suggesting that the effects of lung volume changes on airway tone result from direct effects of stretch on the airway smooth muscle. We analyzed the effect of length oscillation on active force and length-force hysteresis in canine tracheal smooth muscle at different oscillation rates and amplitudes during contraction with acetylcholine. During the shortening phase of the length oscillation cycle, the active force generated by the smooth muscle decreased markedly below the isometric force but returned to isometric force as the muscle was lengthened. Results indicate that at rates comparable to those during tidal breathing, active shortening and yielding of contractile elements contributes to the modulation of force during length oscillation; however, the depression of force during shortening cannot be accounted for by cross-bridge properties, shortening-induced cross-bridge deactivation, or active relaxation. We conclude that the depression of contractility may be a function of the plasticity of the cellular organization of contractile filaments, which enables contractile element length to be reset in relation to smooth muscle cell length as a result of smooth muscle stretch.

Pharmacological modulation of the mechanical response of airway smooth muscle to length oscillation

Stretch and retraction of the airways caused by changes in lung volume may play an important role in regulating airway reactivity. We studied the effects of different pharmacological stimuli on airway smooth muscle to determine whether the muscle behavior during length oscillation can be modulated pharmacologically and to evaluate the role of different activation mechanisms in determining its behavior during the oscillation. Active force decreased below the static isometric force during the shortening phase of length oscillation, resulting in an overall depression of force during the length oscillation cycle. This pattern of response was unaffected by the contractile stimulus or level of activation, suggesting that it was caused by a mechanism that is independent of the level of activation of cross bridges. The normalized area of the length-force hysteresis loop (hysteresivity) differed depending on the stimulus used for contraction. Effects of different stimuli on hysteresivity were not correlated with their effects on isotonic shortening velocity or isometric force, suggesting that the pharmacological modulation of the behavior of airway smooth muscle during length oscillation at these amplitudes cannot be accounted for by the effects on the cross-bridge cycling rate.

Hydrazide as a ligand moiety in immobilized metal ion affinity chromatography. Separation of BO-IMI and BODIPY-hydrazide

BODIPY hydrazide (BO-HZ, a commercially available fluorescent dye) and BO-IMI (obtained by coupling the hydrazide moiety of BODIPY to the carboxyl group of N-acetylhistidine) were separated on three forms of a Sepharose-iminodiacetic acid column: Cu(II), Ni(II) and Zn(II). Whereas BO-IMI eluted first on the Cu(II) and Ni(II) columns (a pH gradient from 7.0 to 2.0 was applied), it eluted last on the Zn(II) column. BO-HZ eluted from the Zn(II) column without displacing this metal. The explanation suggested for these results is that BODIPY hydrazide undergoes strong, bidendate binding only to the Cu(II) and Ni(II) columns.

Effects of simulated weightlessness on erythrocyte deformability in rats

In order to investigate the mechanism of space anemia, the erythrocyte deformability membrane fluidity and cell shape in 7, 15, 30 day tail-suspended rats were observed. The results were: (1) erythrocyte deformability (DImax and IDI) in suspended rats was significantly lower than that in the control on the 7th day (P<0.05), and had a further decrease on the 15th day (P<0.01), but a recovery was found on the 30th day (P<0.05). (2) membrane fluidity in suspended rats was markedly lower than that in the control group on the 15th and 30th day, degrees of fluorescence polarization was increased (P<0.01), but there was no change on the 7th day. (3) percentage of erythrocytes with abnormal shape in suspended rats was higher than that in the control group during the whole experimental period. The results indicate that the changes of rheological and morphological properties of red cell were induced by simulated weightlessness (SWL), which may be an important cause of space anemia.

Two new limonoids from the seeds of Microula sikkimensis

Two new limonoids, cis-p-hydroxycinnamoylrutaevin and trans-p-hydroxycinnamoylrutaevin were isolated along with three known limonoids. Their structures were deduced on the basis of their spectral data. This is the first report on the isolation of limonoids from seeds of Microula sikkimensis Hemsl.

Changes in ovarian expression of tissue-type plasminogen activator and plasminogen activator inhibitor type-1 messenger ribonucleic acids during ovulation in rat

We investigated the time course and localization of ovarian tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor type-1 (PAI-1) expression during the ovulatory period in rat by RNase protection assay and in situ hybridization. Immature female Wistar rats were injected with 25 IU pregnant mare serum gonadotropin (PMSG), followed 50 h later by 25 IU human chorionic gonadotropin (hCG). Levels of tPA mRNA were low before hormone treatment and after PMSG treatment. After hCG treatment, tPA mRNA levels increased rapidly, the first peak at 4 h after hCG treatment and reached a maximum just prior to ovulation, 12 h later, before declining again. PAI-1 mRNA was barely detectable before hormone treatment but was transiently induced by hCG treatment, reaching peak levels after 4 h. Subsequently, PAI-1 mRNA levels decreased until early luteinization. The expression of tPA mRNA 4 h after hCG treatment occurred mainly in the follicular thecal-interstitial cells, but was barely detectable in the granulosa cells, whereas 12 h after hCG treatment it was maximal in the granulosa cells of the large follicles destined to ovulate. PAI-1 mRNA was expressed mainly in ovarian stromal tissue and in the thecal external interstitial cells encapsulating the follicles at 4 h after hCG treatment. These results suggest that the temporal regulation of tPA biosynthesis after hCG induction depends on the cell types and size classes in the various ovarian compartments. PAI-1 may be produced by the stormal tissue and the thecal external interstitial cells and is perhaps implicated in structural changes during follicular growth, ovulation and luteinization.

[Observation of changes of cardiovascular function during 2.5h HDT (-15 degrees) with sphygmogram method]

To understand the changes of cardiovascular functions in the initial stage of space flight, the changes in 19 healthy young men during 2.5h head down tilt (HDT) (15 degrees) were observed with CF-II cardiovascular function detecting and diagnosing equipment. The blood pressure and sphygmogram of left radial arterial were recorded in sedentary condition and at 10th, 30th, 60th, 90th, 120th and 140th minute of HDT. The results showed that changes of cardiovascular indices during HDT can be divided into acute regulation stage (< 1h) and the regulation stage (1-2.5 h); circulatory blood volume, stroke volume and cardiac output were increased, while heart rate, pre and after load of the heart, CVP, coronary circulatory function, blood pressure and systemic vascular resistance were decreased; the vagus feedback index increased and the regulation function of vasscule decreased. Most of the changes of cardiovascular indices as reflected in the sphygmogram are in consistent with the reported result in space flight or simulated micro-G, so the sphygmogram method might be applied to space medical research.

Detection of human herpesvirus 6(HHV-6) DNA in salivary glands by the polymerase chain reaction

To assess the presence of HHV-6-Specific DNA in human salivary glands, eighteen specimens of salivary gland tissue were investigated using the polymerase chain reaction. Eight of nine parotid glands, five of seven submandibular glands and one of two sublingual glands were found to have amplification of the HHV-6-specific sequence. The findings suggest that salivary gland tissue is one of the potential sites for HHV-6 persistence following primary infection and that saliva is a vehicle for transmission of the virus.

Species-specific tRNA recognition in relation to tRNA synthetase contact residues

In spite of variations in the sequences of tRNAs, the genetic code (anticodon trinucleotides) is conserved in evolution. However, non-anticodon nucleotides which are species specific are known to prevent a given tRNA from functioning in all organisms. Conversely, species-specific tRNA contact residues in synthetases should also prevent cross-species acylation in a predictable way. To address this question, we investigated the relatively small tyrosine tRNA synthetase where contacts of Escherichia coli tRNA(Tyr) with the alpha2 dimeric protein have been localized by others to four specific sequence clusters on the three-dimensional structure of the Bacillus stearothermophilus enzyme. We used specific functional tests with a previously not-sequenced and not-characterized Mycobacterium tuberculosis enzyme and showed that it demonstrates species-specific aminoacylation in vivo and in vitro. The specificity observed fits exactly with the presence of the clusters characteristic of those established as important for recognition of E. coli tRNA. Conversely, we noted that a recent analysis of the tyrosine enzyme from the eukaryote pathogen Pneumocystis carinii showed just the opposite species specificity of tRNA recognition. According to our alignments, the sequences of the clusters diverge substantially from those seen with the M. tuberculosis, B. stearothermophilus and other enzymes. Thus, the presence or absence of species-specific residues in tRNA synthetases correlates in both directions with cross-species aminoacylation phenotypes, without reference to the associated tRNA sequences. We suggest that this kind of analysis can identify those synthetase-tRNA covariations which are needed to preserve the genetic code. These co-variations might be exploited to develop novel antibiotics against pathogens such as M. tuberculosis and P. carinii.

E2F4-RB and E2F4-p107 complexes suppress gene expression by transforming growth factor beta through E2F binding sites

Transforming growth factor beta (TGF-beta) causes growth arrest in most cell types. TGF-beta induces hypophosphorylation of retinoblastoma susceptibility gene 1 product (RB), which sequesters E2F factors needed for progression into S phase of the cell cycle, thereby leading to cell cycle arrest at G1. It is possible, however, that the E2F-RB complex induced by TGF-beta may bind to E2F sites and suppress expression of specific genes whose promoters contain E2F binding sites. We show here that TGF-beta treatment of HaCaT cells induced the formation of E2F4-RB and E2F4-p107 complexes, which are capable of binding to E2F sites. Disruption of their binding to DNA with mutation in the E2F sites did not change the expression from promoters of E2F1, B-myb, or HsORC1 genes in cycling HaCaT cells. However, the same mutation stimulated 5- to 6-fold higher expression from all three promoters in cells treated with TGF-beta. These results suggest that E2F binding sites play an essential role in the transcription repression of these genes under TGF-beta treatment. Consistent with their repression of TGF-beta-induced gene expression, introduction of E2F sites into the promoter of cyclin-dependent kinase inhibitor p15(INK4B) gene effectively inhibited its induction by TGF-beta. Experiments utilizing Gal4-RB and Gal4-p107 chimeric constructs demonstrated that either RB or p107 could directly repress TGF-beta induction of p15(INK4B) gene when tethered to p15(INK4B) promoter through Gal4 DNA binding sites. Therefore, E2F functions to bring RB and p107 to E2F sites and represses gene expression by TGF-beta. These results define a specific function for E2F4-RB and E2F4-p107 complexes in gene repression under TGF-beta treatment, which may constitute an integral part of the TGF-beta-induced growth arrest program.

Quantification of latent tissue reservoirs and total body viral load in HIV-1 infection

The capacity of HIV-1 to establish latent infection of CD4+ T cells may allow viral persistence despite immune responses and antiretroviral therapy. Measurements of infectious virus and viral RNA in plasma and of infectious virus, viral DNA and viral messenger RNA species in infected cells all suggest that HIV-1 replication continues throughout the course of infection. Uncertainty remains over what fraction of CD4+ T cells are infected and whether there are latent reservoirs for the virus. We show here that during the asymptomatic phase of infection there is an extremely low total body load of latently infected resting CD4+ T cells with replication-competent integrated provirus (<10(7) cells). The most prevalent form of HIV-1 DNA in resting and activated CD4+ T cells is a full-length, linear, unintegrated form that is not replication competent. The infection progresses even though at any given time in the lymphoid tissues integrated HIV-1 DNA is present in only a minute fraction of the susceptible populations, including resting and activated CD4+ T cells and macrophages.

Chemical composition and microstructure of uroliths and urinary sediment crystals associated with the feeding of high-level cottonseed meal diet to water buffalo calves

The chemical composition and microstructure of seven uroliths and four urinary sediment samples associated with the feeding of high-level cottonseed meal diet to buffalo calves were examined by chemical qualitative analyses, scanning electron microscopy (SEM), X-ray diffraction, and X-ray energy dispersive spectrometry (EDS). Struvite was a major component of kidney stones and of some bladder stones. The kidney stone sample appeared cracked under low power under SEM, aggregated into tiny balls under high power, and as a blade-like structure under even higher power. The bladder stone samples appeared finely granular or granular with various forms of prismatic crystals. The urinary sediments were prismatic crystals, with granules. The newly found prismatic crystals, which were rich in potassium and similar to struvite in crystal structure, were identified as potassium magnesium phosphate (KMgPO4.6H2O) in some bladder stones and urinary sediments. However, crystals which contained Mg and P only, which had been used for struvite identification, were not found by EDS examination in urinary sediments from fresh urine samples of buffalo calves fed the high-level cottonseed meal diet.

Integrated regulation in response to simulated weightlessness

To investigate physiological effects of tail suspension, Ca2+ concentration, immune factors, erythrocyte rheological properties, and growth hormone were determined in rats suspended for 15 and 30 d. The results showed that inhibitory changes of both local factors (proteins secreted by bone cell, Ca(2+)-ATPase in sarcoplasmic reticium) and integrated regulative factors (immune factor, growth hormone) were observed simultaneously with the decrease of bone mineral content, calcium transportation in skeletal muscles as well as erythrocyte deformability. It suggests that both local and integrated regulative processes are functioning in response to the effects of weightlessness.

[Lead exposure level in umbilical cord blood and its related factors]

Six hundred and five specimens of umbilical cord blood were collected from Yangpu District, Shanghai, and blood lead levels were determined with graphite stove atom absorption spectrophotometry in 348 of them to study fetal exposure to lead and its related factors in the people of Shanghai. Survey on household social and environmental health status was conducted in families with the babies whose umbilical cord blood lead were above the 70th percentile and below the 30th percentile with a face-to-face questionnaire. Data were analyzed with multiple regression for the factors which affected the lead level in umbilical cord blood significantly. Results showed that blood lead levels in 348 cases were normally distributed, with a range of 0.08 to 0.84 mumol/L, a mean of 0.44 mumol/L and a standard deviation of 0.15 mumol/L. Specimens with cord blood lead level exceeding the safety criteria of 0.48 mumol/L accounted for 40.8 percent of the total. The study also found that passive smoking during pregnancy, exposure to lead in family members, one's living room adjacent to the major traffic roads, pollution by coal-burning smoke in the environment of one's residence, use of coal as domestic fuel, and eating preserved eggs during pregnancy all were risk factors for lead exposure. Multiple logistic regression analysis revealed that contribution of passive smoking to cord blood lead level was still statistically significant after adjusting other confounding factors. It concluded that environmental lead pollution could cause ad-verse effects on fetal development.

Greater airway narrowing in immature than in mature rabbits during methacholine challenge

It has been demonstrated that methacholine (MCh) challenge produces a greater increase in lung resistance in immature than in mature rabbits (R. S. Tepper, X. Shen, E. Bakan, and S. J. Gunst. J. Appl. Physiol. 79: 1190-1198, 1995). To determine whether this maturational difference in the response to MCh was primarily related to changes in airway resistance (Raw) or changes in tissue resistance, we assessed airway narrowing in 1-, 2-, and 6-mo-old rabbits during intravenous MCh challenge (0.01-5.0 mg/kg). Airway narrowing was determined from measurements of Raw in vivo and from morphometric measurements on lung sections obtained after rapidly freezing the lung after the MCh challenge. The fold increase in Raw was significantly greater for 1- and 2-mo-old animals than for 6-mo-old animals. Similarly, the degree of airway narrowing assessed morphometrically was significantly greater for 1- and 2-mo-old animals than for 6-mo-old animals. The fold increase in Raw was highly correlated with the degree of airway narrowing assessed morphometrically (r2 = 0.82, P < 0.001). We conclude that the maturational difference in the effect of MCh on lung resistance is primarily caused by greater airway narrowing in the immature rabbits.

Mechanism of interferon action sequence of the human interferon-inducible RNA-dependent protein kinase (PKR) deduced from genomic clones

The pkr gene encoding the interferon-inducible, RNA-dependent protein kinase was isolated as lambda phage and P1 phage clones from human genomic DNA and characterized by restriction mapping, Southern blot analysis, and nucleotide sequencing. The genomic nucleotide sequence, when compared to that of previously determined cDNA sequences, revealed 17 exons encoding the 551-amino-acid PKR protein. We report herein the sequence of the human PKR protein kinase deduced from genomic clones.

[Repair of acute thumb avulsion with the bi-lobed island flap of the second web]

The authors designed a bi-lobed island flap of the second web pedicled with the first and the second dorsal metacarpal arteries. Since 1993, five cases of acute thumb avulsion have been repaired using this flap. The size of the flaps ranged from 3 cm x 6 cm to 6 cm x 7 cm. All flaps survived with primary healing of the incisions. Three to nine months' follow-up showed that the flaps were thin and had sensation. The function and appearance of the reconstructed thumb were satisfactory. The bi-lobed island flap of the second web is a valuable method for the repair of thumb avulsion.

Structural organization of the human gene (PKR) encoding an interferon-inducible RNA-dependent protein kinase (PKR) and differences from its mouse homolog

The gene encoding the interferon-inducible, RNA-dependent protein kinase (PKR) was isolated as lambda phage and P1 phage clones from human genomic DNA libraries and characterized by Southern blot and nucleotide sequence analyses. Southern blot analyses were consistent with a single PKR gene, and genomic clones colocalized by fluorescence in situ hybridization to human chromosome 2p. Sequence analysis demonstrated that the human PKR gene consists of 17 exons and spans about 50 kb. The AUG translation initiation site for the 551-amino-acid PKR protein was located in exon 3; exon 17 was the largest exon and included the UAG translation termination site, AUUAAA polyadenylation signal, and putative C(A) 3' cleavage site. Two RNA-binding motifs, RI and RII, were present in exons 4 and 6, respectively, and the codon phasing of these exon junctions was conserved between them. The organization of the regulatory and catalytic subdomains of the PKR protein was remarkably preserved between the human and the mouse PKR genes; the amino acid junction positions for 13 of the 15 protein coding exons were exactly conserved.

Linker histone H1 regulates specific gene expression but not global transcription in vivo

In a linker histone H1 knockout strain (delta H1) of Tetrahymena thermophila, the number of mature RNAs produced by genes transcribed by pol I and pol III and of most genes transcribed by pol II remains unchanged. However, H1 is required for the normal basal repression of a gene (ngoA) in growing cells but is not required for its activated expression in starved cells. Surprisingly, H1 is required for the activated expression of another gene (CyP) in starved cells but not for its repression in growing cells. Thus, H1 does not have a major effect on global transcription but can act as either a positive or negative gene-specific regulator of transcription in vivo.