Protective immunity to HIV-1 in SCID/beige mice reconstituted with peripheral blood lymphocytes of exposed but uninfected individuals

Immunodeficiency typically appears many years after initial HIV infection. This long, essentially asymptomatic period contributes to the transmission of HIV in human populations. In rare instances, clearance of HIV-1 infection has been observed, particularly in infants. There are also reports of individuals who have been frequently exposed to HIV-1 but remain seronegative for the virus, and it has been hypothesized that these individuals are resistant to infection by HIV-1. However, little is known about the mechanism of immune clearance or protection against HIV-1 in these high-risk individuals because it is difficult to directly demonstrate in vivo protective immunity. Although most of these high-risk individuals show an HIV-1-specific cell-mediated immune response using in vitro assays, their peripheral blood lymphocytes (PBLs) are still susceptible to HIV infection in tissue culture. To study this further in vivo, we have established a humanized SCID mouse infection model whereby T-, B-, and natural killer-cell defective SCID/beige mice that have been reconstituted with normal human PBLs can be infected with HIV-1. When the SCID/beige mice were reconstituted with PBLs from two different multiply exposed HIV-1 seronegative individuals, the mice showed resistance to infection by two strains of HIV-1 (macrophage tropic and T cell tropic), although the same PBLs were easily infected in vitro. Mice reconstituted with PBLs from non-HIV-exposed controls were readily infected. When the same reconstituted mice were depleted of human CD8 T cells, however, they became susceptible to HIV-1 infection, indicating that the in vivo protection required CD8 T cells. This provides clear experimental evidence that some multiply exposed, HIV-1-negative individuals have in vivo protective immunity that is CD8 T cell-dependent. Understanding the mechanism of such protective immunity is critical to the design and testing of effective prophylactic vaccines and immunotherapeutic regimens.

Mof4-1 is an allele of the UPF1/IFS2 gene which affects both mRNA turnover and -1 ribosomal frameshifting efficiency

The mof4-1 (maintenance of frame) allele in the yeast Saccharomyces cerevisiae was isolated as a chromosomal mutation that increased the efficiency of -1 ribosomal frameshifting at the L-A virus frameshift site and caused loss of M1, the satellite virus of L-A. Here, we demonstrate that strains harboring the mof4-1 allele inactivated the nonsense-mediated mRNA decay pathway. The MOF4 gene was shown to be allelic to UPF1, a gene whose product is involved in the nonsense-mediated mRNA decay pathway. Although cells harboring the mof4-1 allele of the UPF1 gene lose the M1 virus, mutations in other UPF genes involved in nonsense-mediated mRNA decay maintain the M1 virus. The mof4-1 strain is more sensitive to the aminoglycoside antibiotic paromomycin than a upf1 delta strain, and frameshifting efficiency increases in a mof4-1 strain grown in the presence of this drug. Further, the ifs1 and ifs2 alleles previously identified as mutations that enhance frameshifting were shown to be allelic to the UPF2 and UPF1 genes, respectively, and both ifs strains maintained M1. These results indicate that mof4-1 is a unique allele of the UPF1 gene and that the gene product of the mof4-1 allele affects both -1 ribosomal frameshifting and mRNA turnover.

A novel variant of the beta-subunit of the amiloride-sensitive sodium channel in African Americans

The amiloride-sensitive sodium channel is responsible for the rate-limiting step of sodium reabsorption in the distal renal tubule, and thus may play a key role in the maintenance of sodium balance and blood pressure. In this study, a genetic variant that results in a change of threonine to methionine at amino acid 594 (T594 M) in the carboxy-terminus of the beta-subunit of the amiloride-sensitive sodium channel has been identified. This variant was present in 6.1% of African-American subjects (N = 231) but was not seen in Caucasians (N = 192). Whole cell voltage clamp of B-lymphocytes from individuals with the T594 M variant showed similar basal membrane slope conductance, compared with the wild-type but increased response to cAMP analog.

Fos is required for EGF stimulation of the gastrin promoter

Gastrin gene expression is regulated by developmental cues, pH, and inflammation. These processes are mediated by various extracellular ligands, e.g., growth factors, cytokines, and neuropeptides that also stimulate c-fos gene expression. Therefore, to determine whether Fos is required for stimulation of the gastrin promoter, a c-fos sense expression vector was coexpressed with a gastrin reporter construct in a GH4 rat pituitary cell line. We found that epidermal growth factor (EGF) and tumor necrosis factor-alpha (TNF-alpha) transiently stimulate an increase in Fos protein that precedes stimulation of the gastrin promoter. However, the induction mediated by TNF-alpha was weaker than that mediated by EGF, indicating minimal overlap of the signaling pathways activated by EGF and TNF-alpha. Accordingly, overexpression of c-fos mRNA facilitated primarily EGF rather than TNF-alpha induction of the gastrin promoter. Expression of the c-fos gene in the absence of ligand did not stimulate the gastrin promoter. Thus c-fos gene expression is required but is not sufficient for induction of the gastrin promoter by EGF.

Analysis of thymoma excision in patients with myasthenia gravis

OBJECTIVE

To study the clinical characteristics of myasthenia gravis (MG) with thymoma and the effect of tracheostomy at the early stage after operation.

METHODS

Thymoma excision and selective tracheostomy were performed on 46 patients with MG from March 1983 to December 1994.

RESULTS

There were 15 patients with benign thymomas and 31 patients with malignant thymomas. MG crises were seen in 52.2% of patients postoperatively, most in type IIb and III. The mortality of in-patients after operation was 10.9%. Thirty-nine patients with thymoma were followed up for 6 months to 12 years after being discharged from hospital. The MG symptoms were relieved in 33.3%, improved in 20.5% and unchanged in 2.6% of patients. 38.5% of patients died of the disease.

CONCLUSION

The characteristics of MG with thymoma are, more severe condition of the patient, rapid advance, and more MG crises before and after operation. The perioperative mortality from MG with thymoma is higher and its prognosis is unfavourable. It is very important to treat severe cases of MG with thymoma by tracheostomy with thymoma excision at the early stage after the operation. This is an effective method to prevent and treat MG crises as well as to lower the perioperative mortality.

Synergistic effects of Vg1 and Wnt signals in the specification of dorsal mesoderm and endoderm

In amphibians, dorsoventral asymmetry is established by cortical rotation, a cytoplasmic rearrangement in the egg which activates a dorsal determinant on one side of the zygote. This determinant has been proposed to be either Vgl, an endodermally derived molecule that can directly induce ectoderm to form dorsal mesoderm, or a member of the Wnt family, which patterns the ectoderm such that it forms dorsal mesoderm in response to ventral inductive signals. In this study, we have investigated whether the endogenous dorsal determinant(s) functions as a direct inducer of dorsal mesoderm (Vg1-like) or whether it acts to pattern the response of ectoderm to inductive signals (Wnt-like). We report here that cortical rotation enhances both the dorsal-inductive activity of endodermal cells and the response of ectodermal cells to endogenous inductive signals and that both of these activities are required for notochord induction in ectoderm/endoderm recombinants. While ectopically expressed Xwnt-8b can substitute for the dorsalizing signals activated in either ectoderm or endoderm, and can allow notochord formation in recombinants, Vg1 alone is not sufficient to induce notochord in ectodermal explants in the absence of signals activated by cortical rotation. Coexpression of Xwnt-8b along with Vg1 restores ectodermal competence to form notochord. Finally, in endodermal explants, ectopically expressed Xwnt-8b, but not Vg1, can divert the fate of ventral endodermal cells along a dorsal pathway. Thus, while Vg1 is most likely required for induction of mesoderm in vivo, our data suggest that a maternal Wnt-like signal acts synergistically with Vg1 to specify a dorsal fate not only in the mesoderm, but also in the endoderm.

The RsmA- mutants of Erwinia carotovora subsp. carotovora strain Ecc71 overexpress hrpNEcc and elicit a hypersensitive reaction-like response in tobacco leaves

Erwinia carotovora subsp. carotovora wild-type strain Ecc71 does not elicit the hypersensitive reaction (HR) in tobacco leaves. By mini-Tn5-Km and chemical mutagenesis we have isolated RsmA- mutants of Ecc71 that produce high basal levels of pectate lyases, polygalacturonase, cellulase, and protease; they also are hypervirulent. The RsmA- mutants, but not their parent strains, elicit an HR-like response in tobacco leaves. This reaction is characterized by the rapid appearance of water soaking followed by tissue collapse and necrosis. The affected areas remain limited to the region infiltrated with bacterial cells, and the symptoms closely resemble a typical HR, e.g., the reactions caused by Pseudomonas syringae pv. pisi. Moreover, low concentrations of cells of the mini-Tn5-Km insertion RsmA- mutant, AC5070, infiltrated into tobacco leaf tissue prevent elicitation of the rapid necrosis by AC5070 or by P. syringae pv. pisi. Elicitation of the HR-like response by the mutants is not affected by the deficiency of N-(3-oxohexanoyl)-L-homoserine lactone, the cell density (quorum) sensing signal. Cloning and sequence analysis have disclosed that E. carotovora subsp. carotovora strain Ecc71 possesses a homolog of E. chrysanthemi hrpN known to encode an elicitor of the HR; the corresponding Ecc71 gene is designated hrpNEcc. Northern (RNA) blot data show that the level of hrpNEcc mRNA is considerably higher in the RsmA- mutants than in the RsmA+ strains. Moreover, a low copy plasmid carrying the rsmA+ allele severely reduces the level of the hrpNEcc transcripts in the RsmA- mutants. These constructs, like the RsmA+ E. carotovora subsp. carotovora strains, do not elicit the HR-like response. These data taken along with the effects of rsmA on exoenzyme production and pathogenicity (A. Chatterjee et al., 1995, Appl. Environ. Microbiol. 61:1959-1967) demonstrate that this global regulator gene plays a critical role in plant interaction of E. carotovora subsp. carotovora.

Determination of the refractive index and thickness of transparent pellicles by use of the polarization-independent absentee-layer condition

The refractive index and the thickness of a transparent pellicle are determined when the pellicle is placed between two vertical crossed polarizers and rotated in the horizontal plane. The transmission axes of the polarizers are neither parallel nor perpendicular to the plane of incidence. The light transmitted through the crossed polarizers reaches a minimum when the pellicle satisfies the absentee-layer condition. The refractive index and the film thickness are obtained from the pellicle orientation angles under such a condition.

Cloning and expression analyses of mouse dystroglycan gene: specific expression in maternal decidua at the peri-implantation stage

While constructing a catalog of mouse cDNAs which are expressed in the maternal-fetal interface during the peri-implantation period, we encountered a 1.6 kb cDNA clone showing a strong sequence similarity to the 3' untranslated region of the human dystroglycan gene. We cloned an additional 1.7 kb cDNA by reverse transcriptase-PCR (RT-PCR) and confirmed that this is a true mouse homolog of human dystroglycan cDNA by sequence analyses, Southern blotting, and genetic mapping of this gene on the distal region of mouse chromosome 9. Although it is well established that dystroglycan, a transmembrane protein, plays an important role in muscle tissues by bridging intracellular dystrophin to the laminin in the extracellular matrix, its role in non-muscle tissues remains elusive. To further investigate the role of the dystroglycan gene at the peri-implantation stage, we analyzed the expression patterns of this gene by in situ hybridization, which revealed that this gene is specifically expressed in decidual cells, especially in the cells surrounding the implantation site at 6.5, 7.5, and 8.5 day post conception (p.c.) stages, but not expressed in non-pregnant endometrial cells of uterus nor in the decidua at 12.5 day p.c. Further analyses by RT-PCR confirmed that the amount of dystroglycan mRNA in 8.5 day p.c. decidua was indeed 100-fold higher than that of non-pregnant uterus and 12.5 day p.c. mature placenta. These results suggest that dystroglycan may work as a mediator for adhesion between decidual cells themselves or between decidual cells and trophoblast cells, and provide a structural and functional support for maintaining pregnancy at its early stage.

Gamma-ray-induced cell killing and chromosome abnormalities in the bone marrow of p53-deficient mice

Resistance to the lethal effects of ionizing radiation has been demonstrated in a wide variety of cell types with defects in the p53 gene (thymocytes, splenic B and T cells, in vitro hemopoietic colony-forming cells and intestinal cells of the mouse, embryo cells of the rat, and human Burkitt's lymphoma cells). In contrast, Slichenmeyer et al. (Cancer Res. 53, 4164-4167, 1993) found no evidence of resistance in fibroblasts derived from p53 null mice. The aim of our study was to compare the radiation response of hemopoietic colony-forming cells (in vitro CFC) and of fibroblastoid colony-forming cells or units (CFU-F) within the same tissue (marrow) in p53 null mice (-/-), heterozygotes (+/-) and wild-type animals (+/+). We have also tested the hypothesis that, in proliferating cells, radiation-induced cell killing is mediated through chromosome damage by examining the relationship between these end points in hemopoietic cells of the three mouse types. Both in vitro CFC and CFU-F of -/- mice were resistant to cell killing compared with +/+ and +/- mice whose cellular sensitivities were indistinguishable. The resistance was characterized by a broader "shoulder" on the cell survival curve, i.e. a higher extrapolation number but similar D0 values using the multitarget model or a lower alpha coefficient using the linear-quadratic model. The frequency of chromosomally abnormal marrow cells after irradiation was similar for the three genotypes. However, marrow cells with aberrations carried more aberrations in -/- mice than in +/+ or +/- mice such that the total number of aberrations per 100 cells was higher in -/- mice. Since there were no differences in the yields of aberrations between genotypes in spleen lymphocytes or in CFU-F (both noncycling at the time of irradiation) and less mitotic inhibition in -/- marrow cells than in +/+ or +/- cells, the chromosomal radiosensitivity of -/- marrow hemopoietic cells might be related to reduced cell cycle delay allowing insufficient time for repair, but other explanations have been considered. We postulate that the radiation resistance of both hemopoietic CFC and CFU-F in -/- mice is a consequence of the failure of DNA/chromosome damage to trigger apoptosis or permanent cell cycle arrest to the same extent as in the +/+ or +/- mice: hence the lack of correlation between chromosome damage and cell death in the three mouse types.

PTH/PTHrP receptor is temporally regulated during osteoblast differentiation and is associated with collagen synthesis

The temporal sequence of PTH/PTHrP receptor mRNA, binding, biologic activity, and its dependence on matrix synthesis was determined using MC3T3-E1 preosteoblast-like cells and primary rat calvarial cells in vitro. Osteoblastic cells were induced to differentiate and form mineralized nodules with the addition of ascorbic acid and beta-glycerophosphate, and samples were collected from 0-26 days of culture. DNA levels as determined by fluorometric analysis increased 12- and 17-fold during the collection period for both MC3T3-E1 and primary calvarial cells respectively. Steady state mRNA levels for the PTH/PTHrP receptor as determined by northern blot analysis, were initially low for both cell types, peaked at day 4 and 5 for MC3T3-E1 and primary calvarial cells respectively, and declined thereafter. Competition binding curves were performed during differentiation using 125I-PTHrP. The numbers of receptors per microgram DNA were greatest at days 3 and 5 for MC3T3-E1 and primary calvarial cells respectively. The biologic activity of the receptor was evaluated by stimulating the cells with 10 nM PTHrP and determining cAMP levels via a binding protein assay. The PTHrP-stimulated cAMP levels increased 5-fold to peak values at day 5 for MC3T3-E1! cells and 6-fold to peak values at day 4 for the primary calvarial cells. Ascorbic acid was required for maximal development of a PTH-dependent cAMP response since ascorbic acid-treated MC3T3-E1 cells had twice the PTH-stimulated cAMP levels as non-treated cells. When the collagen synthesis inhibitor 3,4-dehydroproline was administered to MC3T3-E1 cultures prior to differentiation, there was a subsequent diminution of the PTH/PTHrP receptor mRNA gene expression and numbers of receptors per cell; however, if administered after the initiation of matrix synthesis there was no reduction in PTH/PTHrP receptor mRNA. These findings indicate that the PTH/PTHrP receptor is associated temporally at the level of mRNA, protein, and biologic activity, with a differentiating, matrix-producing osteoblastic cell in vitro.

Growth factor induction of cytosolic protein tyrosine kinase activity in human haemopoietic progenitor cells isolated by flow cytometry

We employed a highly sensitive method to assay protein tyrosine kinase activity in extracts of subpopulations of CD34+ bone marrow progenitor cells isolated by fluorescence activated cell sorting in an attempt to better define how growth-factor induction of enzymatic activity relates to progenitor cell maturation. FACS analysis confirmed that, under the conditions employed, essentially all of the CD34+ cells in adult human marrow that lacked the CD38 antigen were devoid of the myeloid maturation marker CD33 as well as the lineage antigens: CD10, 13, 14, 15, 16, 19, 71 and glycophorin A. A variable portion (50-90%) of these CD34+, CD38- progenitor cells expressed HLA-DR. CD34+, CD38- cells that did not express HLA-DR were found to lack detectable levels of either membrane or cytosolic tyrosine kinase activity. HLA-DR+ progenitor cells that lacked CD38 possessed elevated levels of cytosolic tyrosine kinase activity but only low levels of plasma membrane activity. In contrast, CD34+ cells that expressed CD38 (and HLA-DR) possessed high levels of membrane-associated tyrosine kinase activity. A cocktail of haemopoietic growth factors that included IL-3, IL-6 and stem cell factor effectively induced tyrosine kinase activity in CD34+, CD38-, HLA-DR- progenitor cells. Growth factor induction of tyrosine kinase activity in these cells was not inhibited by actinomycin D or cyclohexamide. Most of the tyrosine kinase activity induced by these growth factors was recovered from the cytosolic fraction of disrupted cells. Thus, induction of cytosolic tyrosine kinase activity is an early event in the response of uncommitted haemopoietic cells to haemopoietic growth factors. Subsequent activation of membrane tyrosine kinases may initiate key transduction processes as these cells begin to differentiate.

Identification and functional role of beta-adrenergic receptor subtypes in primate and rodent: in vivo versus isolated myocytes

We determined the relationship between the beta 1- and beta 2-adrenergic receptor subtypes in isolated myocytes and their physiological responsiveness in chronically instrumented conscious baboons and rats. In conscious baboons, isoproterenol (ISO) (0.02 microgram/kg) increased left ventricular (LV) dP/dt by 89 +/- 6.7% from 2898 +/- 370 mmHg/s and only by 13 +/- 3.3% from 2491 +/- 146 mmHg/s after beta 1-adrenergic receptor blockade, indicating that the predominant physiological response was mediated by beta 1-adrenergic receptors. Decreases in mean arterial pressure (-11 +/- 0.5 mmHg v -16 +/- 4.6 mmHg) and coronary vascular resistance (-3.1 +/- 0.4 v -3.6 +/- 0.4 mmHg/ml/min) induced by ISO were not different before and after beta 1-blockade, indicating that beta 2-adrenergic receptors were not blocked. In conscious rats, ISO (0.4 microgram/kg) increased LV dP/dt by 50 +/- 4.9% from 13252 +/- 2002 mmHg/s and only by 10 +/- 3.9% from 10793 +/- 1364 mmHg/s after beta 1-adrenergic receptor blockade: whereas decreases in mean arterial pressure induced by ISO were not different before and after beta 1-blockade (-19 +/- 2.4 mmHg v -16 +/- 2.2 mmHg), i.e. very consistent with the physiological responses in baboons. In vitro studies of isolated myocytes, using radioligand binding with 125I-cyanopindolol (125I-cyp) and the subtype beta 1-selective antagonist betaxolol and the beta 2-selective antagonist ICI 118551 indicated that the beta 1/beta 2 ratio of rat myocytes was 92/8: whereas baboon myocytes were more equally distributed (59/41). Thus, in both species the preponderance of effects of ISO on ventricular function was beta 1-adrenergic receptor mediated, which is consistent with the beta 1/beta 2 ratio in rat myocytes but not in baboon myocytes, where a significant fraction of beta 2-adrenergic receptors does not appear to exert an effect on conctractility in vivo.

Messenger functions of phosphatidic acid

Under physiological conditions, phosphatidic acid (PA) is an anionic phospholipid with moderate biological reactivity. Some of its biological effects can be attributed to lyso-PA and diacylglycerol generated by the action of cellular hydrolases. However, it is clear that the parent compound exhibits biological activities of its own. Early studies implicated PA in the transport of Ca++ across plasma membranes as well as in the mobilization of intracellular stored calcium. Both responses may be induced as a consequence of other cellular processes activated by PA, as opposed to being directly mediated by the lipid. PA may be involved in the activation of certain functions confined to specialized groupings of cells, such as the neutrophil superoxide-generating enzyme or actin polymerization. Recent studies implicate PA as an activator of intracellular protein kinases, and a PA-dependent superfamily of kinases involved in cellular signalling has been hypothesized. Deployed on the outer surface of the plasma membrane, PA potentially provides a method of communication between cells in direct contact. This review will explore the known functions of PA as an intracellular mediator and extracellular messenger of biological activities and address ways in which these functions are potentially regulated by cellular enzymes which hydrolyse the phospholipid.

[Fetal erythroblasts from maternal blood for prenatal genetic diagnosis]

OBJECTIVE

To study fetal erythroblasts (FE) from maternal peripheral blood for the diagnosis of fetal aneuploidies.

METHODS

FE expressing the glycophorin A(GPA) were isolated from 13 pregnant women with male fetus (8-14 w) by fluorescence-activated cell sorting(FACS), FE were identified by oligonucleotide primed in situ labelling (PRINS) with Y centromeric satellite DNA primer. The concentration of pregnancy-associated plasma protein A (PAPP-A) was measured by enzyme-labelled immunosorbent assay (ELISA) in serum samples of 41 normal pregnant women (8-14 w). In 5 pregnant women suspicious of fetal Down's syndrome (10-13 w) the serum and FE were examined by PAPP-A, GPA/FACS and PRINS with 21 chromosome centrometric primer.

RESULTS

Detection of flow sorted FE from 13 pregnant women by Y primer showed 14.5% of GPA positive signal. There was no difference in serum level of PAPP-A between 5 pregnant women and 41 normal controls, and all GPA positive cell nuclei of the 5 cases displayed two signals with 21 chromosome.

CONCLUSION

Measurement of fetal erythroblasts from maternal blood for the diagnosis of genetic fetal aneuploidies is a promising non-invasive, rapid and reliable technique.

Applications of the normal-incidence rotating-sample ellipsometer to high- and low-spatial-frequency gratings

The normal-incidence rotating-sample ellipsometer is an instrument that can be used to characterize grating surfaces from the measured ratio ρof complex reflection coefficients r(y)/r(x) of light polarized perpendicular and parallel to the grating groove direction. Experimental results at different wavelengths for different gratings with spatial frequencies from 150 to 5880 grooves/mm are presented. The groove depth of the 5880-grooves/mm gold-coated grating can be estimated from the measured ρ and rigorous grating theory.

The leucine-responsive regulatory protein (Lrp) from Escherichia coli. Stoichiometry and minimal requirements for binding to DNA

Lrp (Leucine-responsive regulatory protein) regulates the expression of a number of operons in Escherichia coli. A recent study of DNA sequences recognized by Lrp established the consensus as a 15-bp sequence, YAGHAWATTWTDCTR (Y = C/T, H = "not G," W = A/T, D ="not C," R = A/G) (Cui, Y., Wang, Q., Stormo, G. D., and Calvo, J. M. (1995) J. Bacteriol. 177, 4872-4880). Here we report the stoichiometry of Lrp binding (an Lrp dimer binds to a single binding site) and studies that define the minimal length of DNA required for binding. A double-stranded 15 mer having a sequence that closely matches the consensus does not show measurable binding to Lrp. One or two base pairs of DNA flanking each end are not sufficient for binding, but constructs having 3-5 additional base pairs (21 mer) show relatively strong binding. Single-stranded flanking DNA also contributes to strong binding. The extent of the contribution to binding is dependent upon whether the single strand is on the left or right of the double-stranded region and whether the polarity of the single-stranded DNA is 5' to 3' or 3' to 5'.

In vivo microdialysis study on changes in septal dynorphin and beta-endorphin activities in active and hibernating Columbian ground squirrels

State-dependent changes in extracellular concentration of endogenous opioids in the septum of Columbian ground squirrels were examined in the hibernating and euthermic states using in vivo microdialysis. The order of estimated extracellular concentration was found to be: hibernating > interbout euthermia > non-hibernating euthermia for dynorphin A and interbout euthermia > hibernating > non-hibernating euthermia for beta-endorphin. The apparent turnover rates of dynorphin A during hibernation was 15 times greater than that during euthermic non-hibernation phase and that of beta-endorphin was 8-fold greater. These results demonstrate that subfamilies of endogenous opioids may vary differentially in their activities at different stages of an annual hibernation cycle and may reflect their different roles in the regulation of hibernation.

Overstretching B-DNA: the elastic response of individual double-stranded and single-stranded DNA molecules

Single molecules of double-stranded DNA (dsDNA) were stretched with force-measuring laser tweezers. Under a longitudinal stress of approximately 65 piconewtons (pN), dsDNA molecules in aqueous buffer undergo a highly cooperative transition into a stable form with 5.8 angstroms rise per base pair, that is, 70% longer than B form dsDNA. When the stress was relaxed below 65 pN, the molecules rapidly and reversibly contracted to their normal contour lengths. This transition was affected by changes in the ionic strength of the medium and the water activity or by cross-linking of the two strands of dsDNA. Individual molecules of single-stranded DNA were also stretched giving a persistence length of 7.5 angstroms and a stretch modulus of 800 pN. The overstretched form may play a significant role in the energetics of DNA recombination.

[The role of thoracoscopy in the diagnosis and treatment of lung cancer]

Using video-assisted thoracoscopic techniques in 32 lung cancer patients over the past 3 years, we have performed a vriety of procedures previously accomplished by "open" techniques. This group of patients included stage I (7 patients), stage II-IIIa (10), stage IV (15). Our procedures include wedge resections of lung tumor using endoscopic mechnical stapling devicesin 7 patients; pulmonary lobectomy in 7; lung cancer staging in 7; pleural biopsies and pleurodesis in 11. There were no mortality and no serious complications associated with the procedure. Our experience indicates on expanded role of thoracoscopy in the diagnosis and treatment of lung cancer.

[A study on complicated chromosome translocation by fluorescence in situ hybridization (FISH) of G-banded chromosomes]

An experimental method of fluorescence in situ hybridization (FISH) with conventionally G-band chromosomes was developed to analyze the complex chromosome rearrangements of patients. In order to obtain optimal results of both G-banding and fluorescence signals, it was essential that G-banded chromosomes were fixed with formaldehyde prior to fluorescence in situ hybridization. The karyotype of a patient with spontaneous abortion might be described as 46, XX, t(1; 5; 12) (1pter-->1q25 : : 12q24-->12qter; 5qter-->5p11 : : 1q25-->1qter; 12pter-->12q24 : : 5p11-->5pter) by the analysis of conventional cytogenetics. However, her karyotype should be identified as 46, XX, t(1; 5; 12) (1pter-->1q23 : : 12q22-->12qter; 5qter-->5p11 : : 1q25-->1qter; 12pter-->12q22 : : 1q23-->1q25 : : 5p11-->5pter) with this newly established method. This investigation indicates that this technique described above is a powerful tool to detect complex chromosome rearrangements of patients.

Cytosolic inactivation of translocated neutrophil plasma membrane protein tyrosine phosphatase

Phosphotyrosine phosphatases (PTPases) regulate cellular metabolic activation by reversing the effects of tyrosine kinases activated earlier in intracellular signaling pathways. We coupled fluorescence-activated cell sorter analysis using anti-CD45 monoclonal antibody with direct measurements of enzyme activity in resolved subcellular fractions to define mechanisms that potentially regulate the availability and activity of CD45-PTPase on neutrophil plasma membranes. Neutrophils in freshly obtained blood as well as neutrophils freshly isolated from blood were found to possess detectable levels of plasma membrane CD45 as assessed by immunofluorescence. However, plasma membranes from these cells were essentially devoid of PTPase catalytic activity, which was largely confined to the specific granules. Granulocyte-macrophage colony-stimulating factor (GM-CSF) upregulated both the catalytic and antigenic components of CD45-PTPase on the plasma membrane of these cells. Upregulation was associated with a shift in the particulate subcellular PTPase catalytic activity from the specific granule fraction to the plasma membrane fraction. The tyrosine kinase inhibitor genistein abrogated GM-CSF-promoted upregulation of plasma membrane CD45 PTPase but did not prevent the GM-CSF-dependent decrease in specific granule catalytic activity. Anti-CD45 antibody immunoprecipitated PTPase activity from both specific granules of resting cells and plasma membranes of GM-CSF-treated cells. However, antiphosphotyrosine immunoprecipitated only activity that had translocated to the plasma membrane, suggesting a role for CD45 phosphorylation in translocation. Western analysis confirmed the tyrosine phosphorylation of CD45 in plasma membranes of GM-CSF-treated neutrophils. Preincubation of plasma membranes of GM-CSF-stimulated neutrophils with cytosol from resting cells resulted in a time- and temperature-dependent loss in membrane PTPase as a consequence of the effects of a cytosolic inactivator. Cytosol obtained from stimulated neutrophils possessed substantially reduced levels of this PTPase inactivator. We conclude that activity of the catalytic component of membrane PTPase in circulating neutrophils is regulated by a cytosolic inactivator. Upon stimulation, intact CD45 PTPase is incorporated into the plasma membrane by a process that requires tyrosine phosphorylation. As a result of inhibition of the cytosolic inactivator, the translocated PTPase expresses full activity, thereby amplifying the potential regulatory influence of the enzyme on the cells' functional response.

State-dependent changes of brain endogenous opioids in mammalian hibernation

Endogenous opioids belonging to three opioid families were measured in different states of the hibernation cycle in brain of the Columbian ground squirrels. Using high-performance liquid chromatography-EC detection, the hypothalamic and septal concentrations of met-enkephalin were found to be significantly higher (p < 0.05) in the hibernating state than that in the nonhibernating state. In contrast, met-enkephalin content in the medulla decreased significantly during hibernation. Leuenkephalin content was only increased in the hypothalamus of hibernating animals. Using radioimmunoassay, dynorphin A-like immunoreactivity was observed to increase in the claustrum and striatum, whereas beta-endorphin-like peptides showed a significant increase in the hypothalamus during hibernation. It is evident that the changes in endogenous opioids in brain during hibernation are state dependent, type specific and region specific. These specific alterations of various endogenous opioids may imply their different roles in hibernation.

Sixteen-beam grating-based division-of-amplitude photopolarimeter

A 16-beam grating-based division-of-amplitude photopolarimeter that employs a transmission grating and a linear photodiode detector array has been developed and tested. The transmission grating splits the incident light beam into 16 orders with essentially uniform intensity distribution. Linear polarizers are placed in fanned-out azimuth orientations in different orders, and a quarter-wave retarder is inserted in one order. After calibration, the photopolarimeter makes time-resolved measurements of all the Stokes parameters of the incident light with a precision of 0.001. The calibration and testing of the system at 632.8 nm are presented.

[Scavenging effects of daphnetin and its Cu, Zn complexes on superoxide radical]

The scavenging effects of daphnetin (D) and its Cu, Zn complexes on superoxide radical (O2-.) generated through the photooxidation of riboflavin were studied with human red blood cells (RBC) and RBC membrane as experimental material. The Cu ( II ) complex showed the highest activity. SOD, D and its Cu ( II ), Zn ( II ) complexes were found to have inhibitory effect on the production of lipid peroxide in the membrane, SOD being the best among them.

[Application of serology and 14C-urea breath test to monitoring of the effect of anti-Helicobacter pylori chemotheraphy]

In order to evaluate the value of serology and 14C-urea breath test in monitoring the effect of anti-Helicobacter pylori chemotherapy, at the first stage of this study, endoscopy, 14C-urea breath test and serology (H. pylori IgG antibody measured by ELISA) were performed in 42 of patients before the onset of anti-H pylori chemotherapy and at 1, 3, 6 and 12 months after termination of the treatment. On analyzing the change of the results of breath test and serology during the one year follow-up period in these patients, "above the cutoff value" in breath test and "reduction of A value less than 15% when comparing with pretreatment" in serology were made as the H. pylori positive criteria for monitoring therapeutic effectiveness on H. pylori. At the second stage of this study, total of another 63 of patients were studied to test the accuracy of the monitoring criteria. The results showed that the sensitivity of breath test was all 100.0% and specificity 95.5% and 100.0% respectively at 6 and 12 month after termination of treatment, the sensitivity of serology was all 100.0% and specificity was 50.0% and 83.3% respectively. A scheme for monitoring the effect of anti-H. pylori chemotherapy by combination of 14C-urea breath test and serology is proposed based on this study.

Aberrant progenitors common to megakaryocytic and myeloid cells in a Down's infant with transient abnormal myelopoiesis

Phenotypic characteristics of blasts were studied in a Down's infant with transient abnormal myelopoiesis (TAM). Two major subpopulations were identified: (1) CD33+CD42b+ cells with platelet peroxidase activity, the commitment of which to megakaryocytic lineage was supported by an increased expression of GATA-1 mRNA; (2) CD33+CD34+CD7+CD4+ cells with immature ultrastructure, which could be either immature megakaryocytic or myeloid cells with aberrant differentiation. Mixed colonies containing megakaryocytes and monocyte/macrophages in the peripheral blood suggested the presence of progenitors common to these subpopulations. These results may indicate that subpopulations of blasts with phenotypic diversity could be derived from aberrant common progenitors to megakaryocytic and myeloid lineages in this patient.

Mineralization of bone-like extracellular matrix in the absence of functional osteoblasts

When grown in medium containing ascorbic acid and beta-glycerol phosphate, mouse MC3T3-E1 cells express an osteoblast phenotype and produce a highly mineralized extracellular matrix. The purpose of this study was to independently examine the role of the collagenous matrix and functional osteoblasts on the mineralization process. Cultures with and without an extensive collagenous matrix were prepared by growing MC3T3-E1 cells in the presence and absence of ascorbic acid. Matrix-rich cultures mineralized at much lower calcium phosphate ion products than nonmatrix cultures. At higher ion products, spontaneous precipitation in the medium and cell layers of nonmatrix cultures were observed. In contrast, mineral in matrix-rich cultures was still exclusively associated with collagen fibrils and not with ectopic sites in the cell layer or medium. To examine the effect of cell viability on matrix mineralization, cells were grown 8 or 16 days in the presence of ascorbic acid, then killed and incubated in a mineralizing medium. Significant mineralization was not observed in the collagenous matrix of 8-day killed cultures or age-matched controls. At 16 days mineral was associated with collagen fibrils at specific foci in the matrix of both viable and killed cultures. This observation is consistent with the concept that collagenous matrices must undergo a maturation process before they can support a mineral induction and growth. It further shows that osteoblast-like cells are not required for mineralization of mature matrices, but are required for matrix maturation.

Effects of isoprenaline on delayed rectifier potassium current in isolated guinea pig ventricular myocytes

AIM

To study the effects of isoprenaline (Iso) on the delayed rectifier potassium current (Ik) in isolated guinea pig ventricular myocytes.

METHODS

Single cells were isolated from guinea pig ventricle. Ik was studied under voltage clamp conditions.

RESULTS

When Ik was activated by depolarizing pulses to +40 mV of increasing duration (40-300 ms), Iso 1 mumol . L-1 caused an enhancement in Ik which was larger for longer pulses (150-300 ms). This was also seen when the intracellular calcium was buffered by 1,2-bis(2-aminophenoxy) ethane-N, N, N1, N1-tetraacetic acid (BAPTA). Intracellular application of BAPTA caused a decrease in Ik activated by longer pulses.

CONCLUSION

There were two components of Ik, one of which was modulated by Iso and intracellular Ca2+.

[Quantitative determination of ursolic acid in folium Ilicis cornutae (gouguye) gathered in different and periods]

The content of ursolic acid in Folium Ilicis Cornutae (Gouguye) gathered in different periods from Yongfeng county of Jiangxi province was determined by TLCS method. The result shows that the content appears to be low in samples gathered in April, but about the same in samples of February, June, August, October and December.

Cardiac channel gating charge movements: recovery from inactivation

The nonlinear charge movements which occur during membrane depolarization of cardiac ventricular myocytes (QON) have been previously identified and separated, by kinetic and steady-state criteria, into constituent components arising from the gating of Na channels and Ca channels. In contrast, the nature and time course of the OFF charge movements (QOFF), which follow membrane repolarization have not been as clearly established. In order to address this question cardiac QOFF was studied using small-diameter, 17-day-old embryonic chick ventricular myocytes that can be rapidly and uniformly voltage-clamped. The application of brief (5.4 ms) depolarizing steps were employed to produce Na channel inactivation but little Ca channel inactivation. Following the return of the membrane potential to -100 mV QOFF, measured as the gating current termed IgOFF, displayed two kinetic components. Double exponential fits to IgOFF yielded time constants of a few tenths of a millisecond for the fast component (IgOFFfast) and of 1-2 ms for the slower component (IgOFFslow). The time course and voltage dependence for the slower component suggested that it might be linked to the inactivation, and the recovery from inactivation, of Na channels. In order to identify these kinetic components double-pulse protocols were employed in which the duration of the prepulse and the interval separating the prepulse and test pulse were varied. The time course for the decay of IgOFFslow following a brief inactivating prepulse was similar to the time course for the recovery of the Na channel QON (QNaRecov). Both IgOFFslow and QNaRecov preceded the recovery of the Na channel (ionic) current. The recovery from inactivation of both the Na current and QNa displayed a similar voltage dependence. These experiments have helped to identify the two components of cardiac IgOFF and, therefore, will facilitate the interpretation of further biophysical and pharmacological studies concerning cardiac Na channel and Ca channel gating charge movements.

Identification of a global repressor gene, rsmA, of Erwinia carotovora subsp. carotovora that controls extracellular enzymes, N-(3-oxohexanoyl)-L-homoserine lactone, and pathogenicity in soft-rotting Erwinia spp

The production of extracellular enzymes such as pectate lyase (Pel), polygalacturonase (Peh), cellulase (Cel), and protease (Prt) is activated by the cell density (quorum)-sensing signal, N-(3-oxohexanoyl)-L-homoserine lactone (HSL); plant signals; and aep genes during postexponential growth of Erwinia carotovora subsp. carotovora 71. Studies with mutants of E. carotovora subsp. carotovora 71 derepressed in exoenzyme production led to the identification of a negative regulator gene, rsmA (rsm, repressor of secondary metabolites). Nucleotide sequencing, transcript assays, and protein analysis established that a 183-bp open reading frame encodes the 6.8-kDa RsmA. rsmA has extensive homology with the csrA gene of Escherichia coli, which specifies a negative regulator of carbon storage. Moreover, the suppression of glycogen synthesis in E. coli by rsmA indicates that the Erwinia gene is functionally similar to csrA. Southern hybridizations revealed the presence of rsmA homologs in soft-rotting and non-soft-rotting Erwinia spp. and in other enterobacteria such as Enterobacter aerogenes, E. coli, Salmonella typhimurium, Shigella flexneri, Serratia marcescens, and Yersinia pseudotuberculosis. rsmA suppresses production of Pel, Peh, Cel, and Prt, plant pathogenicity, and synthesis of HSL in E. carotovora subsp. atroseptica, E. carotovora subsp. betavasculorum, E. carotovora subsp. carotovora, and E. chrysanthemi. In the E. carotovora subsp. carotovora 71, rsmA reduces the levels of transcripts of hslI, a luxI homolog required for HSL biosynthesis. This specific effect and the previous finding that HSL is required for extracellular enzyme production and pathogenicity in soft-rotting Erwinia spp. support the hypothesis that rsmA controls these traits by modulating the levels of the cell density (quorum)-sensing signal.

A consensus sequence for binding of Lrp to DNA

Lrp (leucine-responsive regulatory protein) is a major regulatory protein involved in the expression of numerous operons in Escherichia coli. For ilvIH, one of the operons positively regulated by Lrp, Lrp binds to multiple sites upstream of the transcriptional start site and activates transcription. An alignment of 12 Lrp binding sites within ilvIH DNA from two different organisms revealed a tentative consensus sequence AGAAT TTTATTCT (Q. Wang, M. Sacco, E. Ricca, C.T. Lago, M. DeFelice, and J.M. Calvo, Mol. Microbiol. 7:883-891, 1993). To further characterize the binding specificity of Lrp, we used a variation of the Selex procedure of C. Tuerk and L. Gold (Science 249:505-510, 1990) to identify sequences that bound Lrp out of a pool of 10(12) different DNA molecules. We identified 63 related DNA sequences that bound Lrp and estimated their relative binding affinities for Lrp. A consensus sequence derived from analysis of these sequences, YAGHAWATTWT DCTR, where Y = C or T, H = not G, W = A or T, D = not C, and R = A or G, contains clear dyad symmetry and is very similar to the one defined earlier. To test the idea that Lrp in the presence of leucine might bind to a different subset of DNA sequences, we carried out a second selection experiment with leucine present during the binding reactions. DNA sequences selected in the presence or absence of leucine were similar, and leucine did not stimulate binding to any of the sequences that were selected in the presence of leucine. Therefore, it is unlikely that leucine changes the specificity of Lrp binding.

Phorbol ester-induced priming of superoxide generation by phosphatidic acid-stimulated neutrophils and granule-free neutrophil cytoplasts

This study was undertaken to examine the mechanisms involved in polymorphonuclear leukocyte superoxide release stimulated by exogenous phosphatidic acid (PA). Unlike the immediate burst of superoxide release affected by membrane-permeable dioctanoylglycerol (DiC8-DAG), dioctanoyl phosphatidic acid (DiC8-PA) induced superoxide release after a lag period of 5-20 min. This period was considerably reduced or eliminated when cells were primed by substimulatory levels of phorbol myristate acetate (PMA). Granule-depleted neutrophil cytoplasts also responded to DiC8-PA with a burst of superoxide generation. Activation of the cytoplast superoxide generating system in response to DiC8-PA was also significantly faster after cells had been preexposed to substimulatory levels of PMA, indicating that at least a portion of the priming mechanism was independent of PMA-induced degranulation. To further examine the potential mechanism of PMA priming of responses to PA, we evaluated the activity of neutrophil ecto-phosphatidic acid phosphohydrolase (ecto-PA phosphohydrolase), which generates diacylglycerol from exogenous PA. PMA priming had no discernable effect on the activity of this enzyme. In addition, propranolol, an inhibitor of PA phosphohydrolase, did not selectively inhibit PMA priming of neutrophil responses to DiC8-PA, indicating that priming did not result from acceleration of DiC8-PA hydrolysis. We therefore investigated the possibility that activation of protein kinase C was the basis of the primed response. Several semiselective protein kinase C inhibitors (calphostin C, H-7, and acylmethylglycerol) inhibited DiC8-DAG- and DiC8-PA-induced superoxide release as well as PMA-primed responses to approximately the same extent. These results are consistent with the hypothesis that neutrophil responses to phosphatidate are mediated by diglyceride generated by the action of ecto-PA phosphohydrolase. PMA priming does not result from increased catalytic activity of ecto-PA phosphohydrolase but rather seems to result from potentiation of an intermediate involved in the cells' response to multiple stimuli.

Effects of differentiation and transforming growth factor beta 1 on PTH/PTHrP receptor mRNA levels in MC3T3-E1 cells

TGF beta has opposing effects on osteoblasts which are thought to be differentiation stage dependent; however, little is known concerning the effects of TGF beta on osteoblastic characteristics at different stages of maturation. The purpose of this study was to characterize the pattern of mRNA expression for the PTH/PTHrP receptor during normal osteoblastic differentiation in vitro, and evaluate the effects of TGF beta 1 on PTH/PTHrP receptor and osteocalcin (OCN) steady-state mRNA at different stages of osteoblastic differentiation. MC3T3-E1 preosteoblasts were plated at low density and induced to differentiate with ascorbic acid and beta-glycerophosphate. The first group served as a vehicle control and the remaining five groups received a single 48 h TGF beta 1 (3.0 ng/ml)-pulse staggered on a weekly basis for 30 days. Cell cultures were harvested weekly and evaluated for: steady-state PTH/PTHrP receptor and OCN mRNA levels via northern analysis, calcium and phosphorous levels, bone nodules via Von Kossa staining, alkaline phosphatase enzyme levels, and hydroxyproline levels. Group 1 (control) samples followed a normal pattern of proliferation, extracellular matrix deposition, and mineralization. PTH/PTHrP receptor and OCN mRNA expression increased 8-fold and 10-fold respectively, over the collection periods. When TGF beta 1 was administered during the first 48 h period (group 2) while cells were rapidly proliferating, there was a persistent inhibition of PTH/PTHrP receptor expression and a striking reduction in OCN mRNA expression at all time points. There was also a down-regulation of PTH/PTHrP receptor and OCN expression when TGF beta 1 was administered later during osteoblast differentiation (groups 3-6); however, these effects were not persistent. In addition there was a total lack of bone nodule formation in group two cultures, whereas groups 3-6 had increasing bone nodule formation because the TGF beta 1 was administered later in the culture period. These studies indicate that expression of the PTH/PTHrP receptor increases with osteoblastic differentiation and suggest that TGF beta 1 inhibits osteoblastic maturation with more persistent effects found in less differentiated osteoblastic cells.

Multiple subpial transection for treatment of intractable epilepsy

On the basis of experimental study, we applied multiple subpial transection (MST) to treat 50 patients with intractable epilepsy in which epileptigenic lesion involved functional areas such as pericentral gyrus, postcentral gyrus, Broca's area, Wernicke's area, visual cortex, etc. They were followed up for 6 to 40 months. Complete control of seizures was obtained in 32 patients, significant reduction of seizure (more than 50%) in 13, reduction (less than 50%) in 3, and no effect in 2. The total effective rate was 96%. No functional defect was found in all patients. The mechanism of the disease and surgical technique were discussed in detail. We consider that MST could replace some standard excisional therapy for local epilepsy.

Xwnt-8b: a maternally expressed Xenopus Wnt gene with a potential role in establishing the dorsoventral axis

In amphibian embryos, establishment of dorsal-ventral asymmetry is believed to involve dorsal-ventral differences in vegetally derived mesoderm-inducing signals and/or differences in the competence of animal hemisphere (ectodermal) cells to respond to these signals. Previous studies have shown that certain Wnt proteins can generate an ectopic dorsal axis when misexpressed, and that they do so by modifying the response of ectodermal cells to inducers. None of these Wnt proteins are expressed at an appropriate time to do so in vivo. In this study, we describe the isolation and characterization of a full length cDNA for the Xenopus Wnt gene, Xwnt-8b, whose biological activity and expression pattern suggest that it may be involved in establishment of the dorsoventral axis. Both maternal and zygotic Xwnt-8b transcripts undergo alternative splicing to generate mRNAs which encode two different forms of Xwnt-8b protein. During early cleavage stages Xwnt-8b transcripts are confined primarily to animal hemisphere blastomeres, while zygotically derived Xwnt-8b transcripts are restricted almost exclusively to a band of cells in the prospective forebrain of neurula and tailbud stage embryos. Ectopically expressed Xwnt-8b can completely rescue dorsal development of embryos ventralized by exposure to ultraviolet light, and can induce a complete secondary axis in wild-type embryos. Axis induction is observed only if Xwnt-8b is supplied prior to the onset of zygotic gene transcription. This biological activity, together with the presence of maternal Xwnt-8b transcripts in cells that will be induced to form the dorsal mesoderm, is consistent with the possibility that Xwnt-8b may be the endogenous agent that establishes asymmetry in the response of ectodermal cells to mesoderm-inducing signals, thereby initiating dorsal development.

The effect of levonorgestrel-releasing intrauterine device (20 micrograms/day) (LNG-IUD-20) on the morphological structure of human endometrium: a study of the endometrial factor VIII activity in the women before and after insertion of LNG-IUD-20 by the digital image analysis

The specimens of endometria were obtained from 18 women using an intrauterine device releasing levonorgestrel at 20 micrograms/day (LNG-IUD-20). An immunoperoxidase reaction, PAP method, with the antiserum of Factor VIII as the primary antibody, was carried out in the endometrial biopsies to detect the Factor VIII activity in the endometrial endothelium before and after insertion of LNG-IUD-20. The immunoperoxidase activity was quantitatively assessed by a computer digital image analyser. The results revealed that there were a lower Factor VIII activity in the endometrial endothelial cells after insertion of LNG-IUD-20 (p < 0.001) when compared with the control. From the results of the present study, it is suggested that the synthesis and release of endometrial endothelial Factor VIII might be inhibited by the insertion of LNG-IUD20.

[Treating steroids dependent asthmatic patients with high dose beclomethasone dipropionate aerosol]

In order to provide a more effective alternative therapy for the steroid dependent asthmatic (SDA) patients, 23 SDA patients replaced their oral steroids with high dose beclomethasone dipropionate (1500 micrograms/d) inhalation were investigated. The changes of clinical features, pulmonary function and the Synacthen test were recorded. The results showed that about 82% of the patients replaced their oral steroids completely or partially with the inhalation therapy, the clinical features were improved in 13% of the patients and the failure rate was only 4.4%, the results also revealed that, after replacement, the pulmonary function of the patients were improved (P < 0.05); according to the results of Synacthen test, after alternative therapy for 3-6 months, the damaged reserve power and secretive ability of adrenal cortex of the patients were also partially improved (P < 0.01).

Effects of caffeine on background potassium current in isolated guinea pig ventricular myocytes

We investigated effects of caffeine on inward rectifier potassium current (Ik1) in voltage-clamped ventricular cells by slow ramp depolarization (15 mV/s). Caffeine 10 mM applied in the solution bathing the cells consistently reduced the slope of the current-voltage (I-V) relation over the range of -80 to -40 mV. This effect of caffeine was not prevented by loading cells with BAPTA (1,2-bis(2-aminophenoxy) ethane N,N,N',N'-tetra-acetic acid) to suppress contraction. In the absence of caffeine, reducing extracellular potassium from 5.4 to 2.7 mM caused the expected shift of the reversal potential for current in the negative direction and increased rectification. In low potassium, 10 mM caffeine continued to reduce the slope of the I-V relation. When 2 mM barium was applied to suppress Ik1, any effects of 10 mM caffeine were slight or absent. The observations are consistent with a blocking action of caffeine on Ik1 in guinea pig ventricular myocytes.

Inactivation of rsmA leads to overproduction of extracellular pectinases, cellulases, and proteases in Erwinia carotovora subsp. carotovora in the absence of the starvation/cell density-sensing signal, N-(3-oxohexanoyl)-L-homoserine lactone

The soft-rotting bacterium, Erwinia carotovora subsp. carotovora 71, produces extracellular enzymes such as pectate lyase isozymes (Pels), cellulase (Cel), polygalacturonase (Peh), and protease (Prt). While the extracellular levels of these enzymes are extremely low when the bacterium is grown in salts-yeast extract-glycerol (SYG) medium, the enzymatic activities are highly induced in SYG medium supplemented with celery extract. By transposon (mini-Tn5) mutagenesis, we isolated a RsmA- mutant, AC5070, which overproduces extracellular enzymes; the basal levels of Pel, Peh, and Cel in AC5070 are higher than the induced levels in the RsmA+ parent, AC5047. While Peh production is mostly constitutive in AC5070, Pel, Cel, and Prt production is still inducible with celery extract. The high basal levels of pel-1, pel-3, and peh-1 mRNAs in AC5070 demonstrate that overproduction of the pectolytic enzymes is due to the stimulation of transcription. Using chromosomal DNA flanking mini-Tn5 as a probe, we cloned the wild-type rsmA+ allele, which suppresses Pel, Peh, Cel, and Prt production in both RsmA+ and RsmA- strains. The RsmA- mutant, like its parent, produces N-(3-oxohexanoyl)-L-homoserine lactone (HSL), a starvation/cell density-sensing signal required for extracellular enzyme production. To examine the role of HSL, we constructed HSL-deficient strains by replacing hslI, a locus required for HSL production, with hslI::Tn3HoHo1-Spc. While the basal levels of Pel, Peh, Cel, and Prt are comparable in the RsmA- mutant and its HSL- derivative, these enzymes are barely detectable in the Hsl- derivative of the RsmA+ parent strain.(ABSTRACT TRUNCATED AT 250 WORDS)

[Bioavailability study on xiaohuoluo pills]

According to the relationship between dosage and effect, the time course of analgesic was determined after oral administration of Xiaohuoluo Pills to mice. Based on this experiment, contrasting the commercial pills with the reference preparation, the bioavailability of Xiaohuoluo Pills was studied. It was shown that the bioavailability of different batches of product from the same factory was different. This method was good for the study of compound preparations of Chinese materia medica.

Identification and characterization of genes that are required for the accelerated degradation of mRNAs containing a premature translational termination codon

In both prokaryotes and eukaryotes nonsense mutations in a gene can enhance the decay rate of the mRNA transcribed from the gene, a phenomenon described as nonsense-mediated mRNA decay. In yeast, the products of the UPF1 and UPF3 genes are required for this decay pathway, and in this report we focus on the identification and characterization of additional factors required for rapid decay of nonsense-containing mRNAs. We present evidence that the product of the UPF2 gene is a new factor involved in this decay pathway. Mutation of the UPF2 gene or deletion of it from the chromosome resulted in stabilization of nonsense-containing mRNAs, whereas the decay of wild-type transcripts was not affected. The UPF2 gene was isolated, and its transcript was characterized. Our results demonstrate that the UPF2 gene encodes a putative 126.7-kD protein with an acidic region at its carboxyl terminus (-D-E)n found in many nucleolar and transcriptional activator proteins. The UPF2 transcript is 3600 nucleotides in length and contains an intron near its 5' end. The UPF2 gene is dispensable for vegetative growth, but upf2 delta strains were found to be more sensitive to the translational elongation inhibitor cycloheximide than UPF2+. A genetic analysis of other alleles proposed to be involved in nonsense-mediated mRNA decay revealed that the UPF2 gene is allelic to the previously identified sua1 allele, a suppressor of an out-of-frame ATG insertion shown previously to reduce translational initiation from the normal ATG of the CYC1 gene. In addition, we demonstrate that another suppressor of this cyc1 mutation, sua6, is allelic to upf3, a previously identified lesion involved in nonsense-mediated mRNA decay.

A perfusion chamber developed to investigate thrombus formation and shear profiles in flowing native human blood at the apex of well-defined stenoses

The precipitating event leading to stroke, myocardial infarction, and/or sudden death may be related to the formation of mural thrombus at the site of a ruptured or superficially damaged stenotic plaque. The fluid dynamic properties at atherosclerotic plaques that may be implicated in this thrombus formation have been described in a wide variety of model systems in both the process of plaque rupture and the growth of platelet thrombi. In general, the local fluid dynamic conditions are complex and show major variations from flow in well-defined laminar flow systems. However, no studies have attempted to quantify the effect of stenosis-related disturbances on thrombus formation in native human blood and to compare them with the local fluid dynamics. We developed a parallel-plate perfusion chamber device in which thrombus formation is measured at the "apex" of eccentric stenoses and have correlated such measurements with values of the local fluid dynamics obtained by computer simulation. The extent of stenoses (reduction in the cross-sectional area of the blood flow channel) was 60%, 80%, and 89%, corresponding to "apex" wall shear rates of 2600, 10,500, and 32,000 sec-1, respectively. The wall shear rate in the laminar flow region proximal and distal to the stenoses was 420 sec-1. The surface of the stenosis was purified collagen type III fibrils that were exposed to flowing nonanticoagulated human blood drawn directly from an antecubital vein by a pump placed distally to the perfusion chamber. The resulting blood-collagen interactions were quantified by light microscopy by using a morphometric image analysis technique. Under all conditions studied, platelet thrombus formation at the "apex" was extensive.(ABSTRACT TRUNCATED AT 250 WORDS)

[Bleomycin-induced fibroblast proliferation is inhibited by IH764-3]

It reports that IH764-3 has both therapeutical and prophylactic effect on bleomycin-induced pulmonary fibrosis in rats and mice. The data presented indicate that IH764-3 is a potent inhibitor of the two important ways commonly thought to be the main causes of pulmonary fibrosis induced by bleomycin (BLM): 1) BLM stimulates the alveolar macrophages to secrete fibroblast growth factor (FGF); and 2) BLM increases the proliferation rate of the fibroblast directly. This demonstration of suppression of the stimulative effect of BLM on the fibroblast proliferation by IH764-3 provides direct evidence that IH764-3 could be a promising anti-fibrogenetic drug candidate.

Voltage- and concentration-dependent effects of lidocaine on cardiac Na channel gating charge movements

The effects of lidocaine, a local anesthetic and cardiac antiarrhythmic agent, were studied on cardiac nonlinear Na channel and Ca channel charge movements (gating currents) of 17-day-old embryonic chick ventricular myocytes. Gating currents were recorded following the blockade of all ionic currents and the subtraction of the linear capacity currents (-P/5). From a holding potential of -100 mV the ON charge movement (QON) displayed two kinetic components: a rapidly decaying component associated with Ca channel gating, and a slower component associated with Ca channel gating. A depolarizing prepulse to -50 mV for 125 ms reduced the fast component of QON, with little effect on the slower component. Similarly, 20 microM lidocaine also reduced the fast component of QON (Na channel charge movement) and had little effect on the slower component (Ca channel charge movement). Higher concentrations of lidocaine (125 microM) reduced both the fast and the slower components of QON. The effects of either a prepulse to -50 mV, or 20 microM lidocaine on the steady-state QON/Vm relationship were nearly identical. These results suggest that lidocaine "blocks" cardiac Na (ionic) currents by a reduction in the availability of Na channel charge movement (QON), and that this reduction is similar to that produced by voltage-dependent inactivation.

An epidemiological study on the relationship of ectopic pregnancy and the use of contraceptives in Beijing--the incidence of ectopic pregnancy in the Beijing area. Beijing Collaborating Study Group for Ectopic Pregnancy

The incidence of ectopic pregnancy (EP) was studied through a 3-level monitoring network of maternal and child health care (MCH) in the entire Beijing area, including 82 hospitals, 19 MCH centers and 2 institutes for family planning. A total of 1,420 cases of EP were collected in a sample of 2.7 million women of reproductive age (15-49) during a one-year period from January 1 to December 31, 1990. The cases were confirmed by pathological examination or laparoscopy. In addition, epidemiological surveillance method was used. The results showed that the overall incidence of EP was 0.52 per thousand women of reproductive age (W = Women of reproductive age (15-49)) in the Beijing area, 0.6/1000W in the urban districts and 0.41/1000 in the rural area; 0.67/1000W married women, and 0.05/1000W in the unmarried. For married women, 0.54/1000W for those women using various contraceptive measures and 1.80/1000W for women using no contraceptives. The incidence of EP varies with different contraceptive methods. Female sterilization had the lowest incidence (0.18/1000W) and natural contraceptive measures (rhythm or withdrawal method) had the highest (2.43/1000W). It was 0.65/1000W in IUD users, 0.21/1000W in OC users and 0.57/1000W in couples using condoms or spermicides.