The usefulness of fluorinated bonded stationary phases in micellar liquid chromatography (MLC) is examined. Different selectivities and higher efficiencies were observed using a fluoro-octyl (FO) column as compared to that of a C18 column for both non-ionic and ionic compounds in MLC. Shortened analysis times for amino acids and small peptides and increased retention for the early eluting sulfonamides were observed on the FO column. The unique phenomenon of the simultaneous enhancement of solvent strength and selectivity that often occurs in the MLC systems with the alkyl-bonded stationary phases was also observed for the FO column. This is due to the existence of the competing partitioning equilibria in MLC and because of the interactive nature of the two eluent parameters, micelle concentration and the volume fraction of organic modifiers, both of which influence solvent strength and selectivity. Consequently, simultaneous optimization of these two parameters is the most effective strategy for the MLC systems with the fluorinated bonded stationary phases. Subsequently, the iterative regression strategy was utilized to optimize these two mobile phase parameters for a group of amino acids and small peptides. Excellent agreement was obtained between the observed optimum chromatogram and the one predicted by the iterative regression strategy using only five initial experiments. The successful application of the iterative regression optimization procedure indicates that the retention pattern in MLC with fluorinated bonded stationary phases is easily predictable. This is a similar behavior to that using hydrocarbonaceous phases and can be attributed to the linear variations in retention with the two mobile phase parameters and to the highly reproducible retention behavior in MLC.

Chromatography, Liquid↗

PubMed1994

A double hairpin structure is necessary for the efficient encapsidation of spleen necrosis virus retroviral RNA.

We conducted a mutational analysis within the previously defined encapsidation sequence (E) for spleen necrosis virus (SNV), an avian retrovirus. We found that two regions are necessary for efficient SNV replication. The first region is a double hairpin structure as proposed by Konings et al. (1992, J. Virol., 66, 632-640); the second region is located downstream of the hairpins. We showed further that the double hairpin structure is required for efficient SNV RNA encapsidation. Our work is the first to demonstrate, via linker-scanning and site-directed mutagenesis, that a specific RNA secondary structure is required for the encapsidation of retroviral RNA. Analysis of a series of mutations within the E region indicates (i) that preserving the secondary structure of the two hairpins is important for efficient encapsidation and (ii) that the stem regions of the hairpins contain specific sequences critical for encapsidation. Within the hairpins, the presence of at least one of the two conserved GACG four-residue loops, but not the moderately conserved bulge sequence of the first hairpin, is crucial for function. The function of the hairpins is independent of the relative order of the two hairpins. However, the two hairpins are not redundant and are not functionally identical. Replacement of SNV double hairpin sequences with those of Moloney murine leukemia virus (M-MLV) has no detectable effect on the replication of SNV-based retrovirus vectors with reticuloendotheliosis virus strain A (REV-A) helper virus. Furthermore, replacement of the entire E sequence of SNV with that of Moloney murine sarcoma virus (M-MSV) and M-MLV results in retroviral vectors that replicate as well as SNV vectors with wild type SNV E. This result indicates that the encapsidation sequences of M-MSV/M-MLV and SNV are not virus specific and that, during packaging of SNV and MLV RNA with viral proteins from REV-A, the encapsidation sequences are recognized largely by their secondary or tertiary structures.

Animals↗

PubMed1994

Symmetry determination of the EL2 defect by numerical fitting of capacitance transients under uniaxial stress.

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Journal Article↗

PubMed1994

Cell surface control of differentiation in Acanthamoeba.

Acanthamoeba castellanii (Neff) is a free-living soil amoeba with close relatives that are opportunistic pathogens. Trophozoites differentiate into cysts when deprived of nutrients; cysts convert into trophozoites, leaving the wall behind, in the presence of nutrients. The data presented here, which includes immunoaffinity purification of the receptor, indicate that cell surface molecular signals also control Acanthamoeba differentiation in both directions. Monoclonal antibodies that bind specifically to a 40 kD trophozoite protein initiate the encystment of trophozoites. When bound to cysts the same monoclonal antibodies prevent excystment. Washing away the antibody allows both trophozoites and cysts to resume normal activity. One of these monoclonal antibodies inhibits pinocytosis, while another has no effect on pinocytosis.

Acanthamoeba↗

PubMed1994

lacZ expression in germline transgenic zebrafish can be detected in living embryos.

Use of transgenic technology in zebrafish has been limited by the inability to efficiently express transgenes in early embryos of F1 and subsequent generations and to rapidly detect transgenic fish. We generated transgenic fish by injecting fertilized eggs with the Escherichia coli lacZ gene under the control of the Xenopus elongation factor 1 alpha transcriptional regulatory element. Four of five lines of transgenic fish we obtained express the lacZ gene in early embryos. The pattern of expression was distinct for each line, with two lines showing extensive expression beginning at approximately the midblastula transition, one showing patchy expression and one showing expression almost exclusively in motor neurons. Expression patterns were stable through the F2 generation in the three lines studied to date. The availability of these lines facilitated the development of a reliable and rapid method for live-staining lacZ-expressing embryos using the substrate fluorescein-di-beta-D-galactopyranoside (FDG). Positive embryos of the two most highly lacZ-expressing lines could be identified after 2-3 min of staining in FDG and then picked out and raised. These observations should prove useful for a variety of studies in zebrafish.

Animals↗

PubMed1994

Molecular characterization of a 65-kilodalton Toxoplasma gondii antigen expressed abundantly in the matrix of tissue cysts.

We describe the cloning and characterization of a novel antigen expressed in the bradyzoite stage of Toxoplasma gondii. A cDNA library was constructed in bacteriophage lambda gt11 Sfi-Not using messenger RNA molecules isolated from cysts of the ME49 strain of T. gondii. The recombinant phage library was subjected to screening with polyclonal antibodies against bradyzoite antigens. This screening identified a recombinant antigen that was recognized strongly by polyclonal antibodies against bradyzoite antigens as well as by sera from mice chronically infected with T. gondii. The native antigen is a protein of 65 kDa that localized to the matrix of the cyst and the cyst wall surrounding the bradyzoites. The antigen was found to be expressed abundantly in cysts but could not be detected in tachyzoites or within the parasitophorous vacuole of tachyzoite infected host cells. Genomic and cDNA sequence of the gene revealed an open reading frame encoding 452 amino acids interrupted by 2 introns: a 503-bp intron located in the 5' untranslated region preceding the protein coding sequence and a 110-bp intron located 95 bp downstream of the first ATG.

Amino Acid Sequence↗

PubMed1994

Localization of the genetic locus for Saethre-Chotzen syndrome to a 6 cM region of chromosome 7 using four cases with apparently balanced translocations at 7p21.2.

Saethre-Chotzen syndrome is a common autosomal dominant form of craniosynostosis, which results in the premature fusion of cranial sutures. Craniosynostosis is commonly associated with abnormalities of 7p; Vortkamp et al. (Nature 352, 539-540) demonstrated that the GLI3 gene in 7p13 was disrupted in, patients with Greig syndrome and, more recently, the linkage of genetic markers from 7p with the Saethre-Chotzen syndrome locus has been reported (2,3). Here we report the analysis by fluorescence in situ hybridization of four patients with Saethre-Chotzen syndrome associated with apparently balanced translocations involving band 7p21.2 and different reciprocal chromosomes. We show that in all four patients the breakpoints in 7p are situated within a 6 cM region flanked by the genetic markers D7S488 and D7S493. These results provide further evidence that the genetic locus for Saethre-Chotzen syndrome is located in distal 7p.

Acrocephalosyndactylia↗

PubMed1994

The efficacy of heparin and antithrombin III in fluid-resuscitated cecal ligation and puncture.

Sepsis/septic shock and multiple organ failure are important causes of morbidity and mortality. Our objective was to study sepsis and organ failure in a fluid-resuscitated septic model. Males S-D rats were anesthetized with halothane, the jugular vein catheterized, and CLP performed. Each rat was maintained in a metabolism cage on continuous intravenous fluid (3 mL/rat). Urine rate and [creatinine]urine were measured daily. At day 5, serum creatinine with chemistry profile, complete blood count, clotting times, and wet lung/body weight ratios were also measured. Glomerular filtration rate (GFR) was measured according to the principle of endogenous creatinine clearance. GFR was correlated with the product of urine rate x [creatinine]urine (R = .79), so that product was used as a daily indicator of GFR. Urine output remained > or = normal during sepsis. Heparin and antithrombin III were tested in this model. The model was associated with 40% mortality, a 60% reduction in platelet count, liver damage, a 75% reduction in renal function, muscle damage, and a normal wet lung/body weight ratio. Treatment with heparin/antithrombin III ameliorated the decrease in GFR (p < .05) observed in the nontreated animals, prevented the septic-induced thrombocytopenia (p < .05), and improved survival (p = .05).

Animals↗

PubMed1994

Effects of glibenclamide on systemic and splanchnic haemodynamics in conscious rats.

1. The effects of the sulphonylurea, glibenclamide (20 mg kg-1, i.v.), at a dose that blocks vascular potassium channels, on systemic and splanchnic haemodynamics (radioactive microspheres) were studied in conscious rats. 2. Glibenclamide significantly decreased cardiac index and hepatic artery blood flow while it significantly increased vascular resistance in systemic, portal and hepatic arterial territories. 3. In rats with suppressed cardiovascular reflexes, glibenclamide induced vasoconstriction in systemic, portal and hepatic arterial territories. 4. Intracerebroventricular administration of glibenclamide did not alter systemic or regional vascular tone. 5. Glibenclamide blunted the vasodilator effect of the potassium channel opener, diazoxide but not that of the L-type calcium channel blocker, nicardipine. 6. Another sulphonylurea, glipizide (20 mg kg-1, i.v.), induced significant systemic and splanchnic vasoconstriction. 7. Thus, the glibenclamide-induced blockade of vascular potassium channels caused a vasoconstriction in the systemic and splanchnic vascular beds. In these territories, therefore, the opening of glibenclamide-sensitive potassium channels might be responsible for a basal vasodilator tone.

Animals↗

PubMed1994

Purinergic axis in cardiac blood vessels. Agonist-mediated release of ATP from cardiac endothelial cells.

Purified endothelial cells isolated from guinea pig hearts by enzymatic perfusion were grown in monolayer culture and used to test the ability of a variety of vasoactive agents to stimulate ATP release from these cells. Stimulation of endothelial cells with the peptide agonist bradykinin (1 nmol/L), acetylcholine (1 mumol/L), serotonin (1 mumol/L), or adenosine 5'-diphosphate (10 mumol/L) resulted in the rapid appearance of ATP in the incubation medium determined with the firefly luciferase assay for ATP. Addition of antagonists for muscarinic (atropine, 0.1 mumol/L) and purinergic (suramin, 100 mumol/L; reactive blue-2, 100 mumol/L) receptors suggested that ATP release from these cells was receptor-mediated. Bradykinin-induced release of ATP was rapid (peak < 30 seconds at 3 nmol/L bradykinin), dose-dependent (EC50, 0.18 nmol/L), and diminished with repeated administration of agonist. Desensitization to bradykinin also affected the ability of acetylcholine to induce release and was reversible when cells were returned to growth conditions for short periods. Measurement of released adenyl purines as their fluorescent N6-ethenopurine derivatives by high-performance liquid chromatography revealed the origin of the purine released to be ATP and confirmed its rapid dephosphorylation. Addition of the purine nucleotide analogues 2-methylthio-ATP (2-methyl-S-ATP), ADP, and beta gamma-methylene ATP to endothelial cell cultures resulted in a dose-dependent increase in the appearance of ATP measured in the medium bathing the cells at 30 seconds, suggesting the presence of ATP-induced ATP release.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗

PubMed1994

Pericardiocentesis and drainage by a silicon rubber line without echocardiographic guidance. Experience in 55 consecutive patients.

Pericardiocentesis and drainage with a silicon rubber line were performed safely in 55 patients via the subxiphoid (80 times) or apical (1 time) approach at the bedside without echocardiographic guidance. The subxiphoid approach, which is close to the posterior of the sternum or the costal cartilage with a small acute-angle (15-30 degrees) to the parietal pericardium in front of the right ventricle, can avoid injuring the heart, liver and lungs. A line with sideholes near the distal end, which provides convenient drainage and has better histocompatibility, can be kept in place for a long period of time (1-82 days). It was also convenient to inject air, drugs or fluid through the line. There were no procedure-related serious complications or deaths. Emergency drainage with the Seldinger technique, especially for small to moderate effusions, is safe and simple.

Catheters, Indwelling↗

PubMed1994

Characterization of human hepatocyte lines derived from normal liver tissue.

Four separate continuous lines of human hepatocytes (HH01, HH02, HH09, HH25) were developed from normal liver tissue by subjecting cocultures of human hepatocytes with rat liver epithelial cells in a highly enriched medium to frequent subculturing. The addition of conditioned medium from either the human hepatoma line Hep G2 or one of these stable human hepatocyte lines (HH09) appeared to facilitate establishment of line HH25. These human hepatocyte lines have been in continuous culture for 2 to 5 yr and consist of approximately 95% human cells by analysis of cell surface antigens. Cytogenetic analysis also confirmed the human origin of these cells and showed clonal origin with abnormal ploidy. Cells in these human hepatocyte lines retain morphological features of hepatocytes by both light and electron microscopy. They also retain glucose-6-phosphatase activity and secrete proteins characteristic of hepatocytes, such as albumin, alpha-fetoprotein and transferrin. After incubation with 13 mumol/L dibenz(a,h) anthracene for 24 hr, each line had detectable activity of aryl hydrocarbon hydroxylase, ethoxyresorufin O-deethylase and methoxyresorufin O-demethylase. Thus, these human hepatocyte lines retain important differentiated characteristics of hepatocytes. Derived from normal liver tissue, they appear to be immortalized. They provide a new model system for studying human hepatocellular drug metabolism. These lines may also be useful for studying the regulation of synthesis of albumin, alpha-fetoprotein and other proteins in human hepatocytes, determining the effects of cytokines and growth factors and designing systems to effect gene transfer into human hepatocytes for the purpose of gene therapy.

Albumins↗

PubMed1994

[Treating old facial nerve paralysis of 260 cases with the acupuncture treatment skill of pause and regress in six parts].

With the acupuncture treatment skill of pause and regress in six parts, we have treated facial paralysis of 260 cases. The other 50 cases were treated with the uniform reinforcing-reducing method as control. The result shows that the effectiveness of the former is better than the latter (P < 0.01). The acupuncture treatment skill of pause and regress in six parts is a new way developed from the reducing method of the traditional reinforcing-reducing method of lifting and thrusting the needle and nine-six reinforcing-reducing method. In addition, the acupuncture points were chosen in the area of the main distribution of the facial nerve. Through the clinical practice, the acupuncture treatment skill is an effective way for treating old facial paralysis.

Acupuncture Therapy↗

PubMed1994

Expression and immunogenicity of tripeptide repeat region on P190 of Plasmodium falciparum.

A DNA fragment, designated as P190TR, encoding amino acid residues of the tripeptide region of the P190 antigen was amplified by polymerase chain reaction from genomic DNA of FCC1/HN Plasmodium falciparum isolated from Hainan Province, China. Upon comparison with the nucleotide sequences of MAD20 allele, it was found that there were five bases substitution in the P190TR which cause amino acid changes. The DNA fragment sequenced were ligated to BamHI and XbaI-digested pGEX-2T vector. Competent E. coli JM109 (DE3) were transformed with either parental or recombinant pGEX-2T for expression. Analysis of soluble cellular proteins revealed the high level expression of GST-P190TR as fusion proteins. Affinity purification of the fusion protein under nondenaturing condition resulted in the removal of almost all other E. coli proteins. The purified P190TR protein was highly immunogenic in rabbits. The antibodies against the recombinant protein recognized the malaria parasite with the titers at 1:320 measured by IFA and antisera from malarial patients reacted with the expressed protein in Western Blot.

Amino Acid Sequence↗