A minor groove binding track in reverse transcriptase.
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Amino Acid Sequence↗
Biomedical subjects
L Li
Publications and source records attributed to L Li.
Pharmacokinetics of vecuronium during acute isovolaemic haemodilution.
To evaluate the effect of acute isovolaemic haemodilution on the pharmacokinetics of vecuronium, we studied 13 patients undergoing haemodilution during surgery and 13 control patients. General anaesthesia was induced with thiopentone 4-6 mg kg-1 and fentanyl 2-4 micrograms kg-1, and maintained with enflurane and 60% nitrous oxide in oxygen. The haemodilution patients underwent major elective plastic surgery with an anticipated surgical loss of more than 600 ml. Haemodilution was achieved by drainage of venous blood and i.v. infusion of lactated Ringer's solution and 6% dextran, during which the packed cell volume and haemoglobin concentration decreased from 45% to 28.1% and from 14.7 g dl-1 to 9.1 g dl-1, respectively. After administration of a bolus of vecuronium 100 micrograms kg-1, an improved fluorimetric assay was used to measure the plasma concentrations of vecuronium for 5 h. The results showed that the disposition kinetics of vecuronium were best described mathematically by a three-compartment open model in the two groups. The mean volume of the central compartment and volume of distribution at steady state were 42.3 (SD 11.8) ml kg-1 and 168.4 (31.5) ml kg-1, respectively, in control patients, and significantly greater (55.2 (13.4) ml kg-1 and 225.9 (53.3) ml kg-1) in the haemodilution patients (P < 0.05). The elimination half-life was 50.3 (11.5) min in control patients and significantly greater (68.2 (15.1) min) in the haemodilution patients (P < 0.05). The half-lives of fast distribution and distribution, mean residual time, area under the plasma concentration curve and plasma clearance were unchanged in patients who underwent haemodilution compared with the control group.
Adolescent↗
Comparison of the gene expression of aspartate beta-D-semialdehyde dehydrogenase at elevated hydrostatic pressure in deep-sea bacteria.
Aspartate beta-D-semialdehyde dehydrogenase genes (asd) were cloned and sequenced from a deep-sea-adapted strictly barophilic bacterium, Shewanella sp. strain DB6705, and a moderately barophilic bacterium, Shewanella sp. strain DSS12. The determined asd sequences of these two strains were very similar, and the identity of the deduced amino acids sequences was 96.2%. The 5'-ends of the asd mRNA from both strains were localized at corresponding sites by primer extension analysis, and two transcriptional starting points, which differed by only 1 base, were detected. In strain DB6705, a pressure-regulated transcript was mainly observed, whereas in strain DSS12, a pressure-tolerant transcript was observed together with the pressure-regulated transcript. Western-blotting analysis showed that the ASD protein was expressed under higher pressure conditions in DB6705, and under all pressure conditions tested in DSS12, as reflected in the primer extension results. Our findings suggest that asd expression controlled by pressure is one of the important mechanisms involved in the adaptation of microorganisms to the deep-sea environment.
Adaptation, Physiological↗
Microvascular anastomotic thrombosis in experimental diabetes mellitus.
An experimental model was developed to investigate the effects of glycemic control and pentoxifylline administration on microvascular anastomotic patency rates in streptozotocin-induced diabetic rats. Diabetes was confirmed by blood glucose levels of more than 300 mg/dl prior to administering insulin and/or pentoxifylline. Microvascular anastomoses of the femoral artery and vein were performed 4 weeks after induction of diabetes. Subsequently, the comparative rates of anastomotic thrombosis in diabetic and nondiabetic groups with or without insulin or pentoxifylline administration were assessed by direct visualization of the anastomotic sites after 4 days. The results suggest that hyperglycemia impairs the post-operative patency of microvascular venous anastomoses. The diabetic animals maintained under insulin regimens that tightly controlled their serum glucose levels (100 to 200 mg/dl) experienced patency rates similar to those of nondiabetic controls (p < 0.05). Pentoxifylline improved microvenous patency at all levels of hyperglycemia studied, suggesting a possible hemorrheologic mechanism for microvascular venous anastomotic thrombus formation in diabetic animals.
Anastomosis, Surgical↗
Special considerations for monitoring vancomycin concentrations in pediatric patients.
The objectives of this study were to estimate the prevalence of low or excessive vancomycin dosing after initiation of treatment in pediatric patients and to determine the factors that are most predictive of optimized vancomycin dosage in this group. Among 74 patients who underwent vancomycin concentration monitoring, low trough (< 4.0 micrograms/ml) and/or peak (< 15.0 micrograms/ml) concentrations were noted in 28 (38%) patients after the initiation of therapy but in only four of the 28 (14%) patients (p = 0.29) after optimization of the initial dosage. There were not toxic peak concentrations (> 60 micrograms/ml) reported during the study. In patients older than 1 month old, 11 low peaks were associated with troughs less than 7.5 micrograms/ml, whereas no low peaks were associated with troughs more than 7.5 micrograms/ml. The significant predictive variables of optimized vancomycin dosage in the reduced regression model (p < 0.00001; adjusted r2 =0.85; n = 36) were (log) initial dose (p < 0.0001), initial trough (p < 0.0001), and age (p = 0.009). Initial peak concentrations were not associated with the optimized dosage (p = 0.50). The results of this study indicate that approximately 40% of all pediatric patients will be at risk of significant underdosing if standard vancomycin dosing guidelines are followed and that patients older than 1 month old with initial trough concentrations less than 7.5 micrograms/ml are at a greater risk of low peak concentrations than individuals with trough concentrations more than 7.5 micrograms/ml. Monitoring vancomycin concentrations appears to be essential to prevent the underdosing of many pediatric patients; however, only initial trough vancomycin concentrations may be needed to optimize dosages.
Adolescent↗
Analysis of T cell receptor AV and BV chain gene expression by infiltrating lymphocytes in Spitz naevi and in halo naevi.
Spitz naevi and halo naevi are benign melanocytic lesions that share many histological features with malignant melanoma. All lesions are characterized by a brisk infiltration of lymphocytes, mainly of the T cell subtype, and halo naevi are known to undergo spontaneous regression. Since the benign nature of Spitz naevi and halo naevi might therefore be caused by specific T cell responses against tumour-associated antigens, it was found of interest to characterize this T cell response in detail. A reverse transcriptase-polymerase chain reaction (RT-PCR)-based method adapted for analysis of paraffin-embedded material combined with Southern blot analysis has been used to analyse the T cell receptor (TCR) AV and BV repertoires of infiltrating lymphocytes in 14 different melanocytic lesions. The results have shown that only a few particular TCRAV and TCRBV regions are expressed in each lesion. To evaluate the T cell response, it is of interest to know the HLA-type of the analysed lesions, since most melanoma-specific effector lymphocytes are CD8+ cytotoxic T cells and therefore HLA class I-restricted. As blood samples were not available from any of these patients, an RT-PCR method using HLA-A2-specific primers was used to analyse for the presence of this allele. The preferentially expressed TCRAV genes were sequenced, and this analysis showed that the high expression of these TCRAV genes was due to a clonal or oligocional expansion of T cells. In summary, the expression of relatively few TCR variable regions indicates a clonal expansion of T cells.
Adolescent↗
Assignment of the casein kinase II gene family to cattle chromosomes.
Theileriosis, or East Coast fever, a parasitic disease in cattle, is associated with overexpression of casein kinase II. Casein kinase II is composed of two catalytic subunits (alpha or alpha') and two regulatory beta subunits. The genes encoding these subunits of casein kinase II were mapped to bovine chromosomes by polymerase chain reaction analysis of a well-characterized bovine x rodent somatic hybrid cell panel. The alpha-subunit (CSNK2A1) was mapped to bovine chromosome 13, the alpha'-subunit (CSNK2A2) to chromosome 5 and the beta-subunit (CSNK2B) to chromosome 23. Both CSNK2A1 and CSNK2B mapped to known regions of conserved synteny between human and cattle, while CSNK2A2 defined a new homology segment between the human and bovine genomes.
Animals↗
Molecular characterization of major histocompatibility complex (B) haplotypes in broiler chickens.
In Leghorn (laying) chickens, susceptibility to a number of infectious diseases is strongly associated with the major histocompatibility (B) complex. Nucleotide sequence data have been published for six class I (B-F) alleles and for class II (B-L beta) alleles or isotypes from 17 Leghorn haplotypes. It is not known if classical B-L or B-F alleles in broilers are identical, at the sequence level, to any Leghorn alleles. This report describes molecular and immunogenetic characterization of two haplotypes from commercial broiler breeder chickens that were originally identified by serology as a single haplotype, but were differentiated serologically in the present work. The two haplotypes, designated BA4 and BA4variant, shared identical B-G restriction fragment length polymorphism patterns, but differed in one B-L beta fragment that cosegregated with the serological B haplotype. Furthermore, the nucleotide sequences of the highly variable exons of an expressed B-L beta II family gene and B-F gene from the two haplotypes were markedly different from each other. Both the B-L beta II family and B-F gene sequences from the BA4 haplotype were identical to the sequences obtained from the reference B21 haplotype in Leghorns; however, in the BA4 haplotype the B-L beta 21 and B-F21 alleles were in linkage with B-G alleles that were not G21. The nucleotide sequences from BA4variant were unique among the reported chicken B-L beta II family and B-F alleles.
Animals↗
Determinants of nocturnal enuresis in England and Scotland in the '90s.
The aim of this study was to assess whether changes have occurred in the determinants of nocturnal enuresis in Scotland and England in comparison with previous studies. The study was based on 22 study areas from a representative English sample, 14 areas from a representative Scottish sample, and 20 areas from an English inner-city sample. A total of 14,674 subjects was included in the analysis from 16,835 eligible children in the age range 5 to 11 years. For the main analysis, an enuretic child was one who wet the bed at least once a week. As expected, the frequency of enuresis was higher in boys and decreased markedly with age in both sexes. Bedwetting was more frequent in: Afro-Caribbean children compared with white children in the representative samples (OR 1.72 95% CI 1.22 to 2.42); those whose mothers smoked at least 10 cigarettes at home compared with non-smokers (OR 1.58 95% CI 1.26 to 1.98); children who had disturbed sleep compared with those who slept well (OR 1.96 95% CI 1.53 to 2.51); those with mothers aged less than 20 years at the child's birth compared with mothers in the age range 25 to 34 (OR 1.63 95% CI 1.20 to 2.22); and in the second- or third-born in the family in comparison with the first-born (OR 1.42 95% CI 1.17 to 1.72). Father's social class was associated with enuresis only in girls. Only 50% of the parents consulted a doctor for enuresis in their child. The percentage was even lower in Afro-Caribbean families (33%). Enuresis continues to be a highly prevalent problem and has not decreased over the last 45 years. We confirm that environmental factors are still important in the aetiology of enuresis. It is surprising that despite the availability of effective treatment only half of parents consult a doctor about the problem.
Black or African American↗
Effect of chitosan on renal function in patients with chronic renal failure.
The effects of chitosan have been investigated on eighty patients with renal failure undergoing long-term stable haemodialysis treatment. The patients were tested after a control treatment period of 1 week. Half were fed 30 chitosan tablets (45 mg chitosan/tablet) three times a day. Ingestion of chitosan effectively reduced total serum cholesterol levels (from 10.14 +/- 4.40 to 5.82 +/- 2.19 mM) and increased serum haemoglobin levels (from 58.2 +/- 12.1 to 68 +/- 9.0 g L-1). Significant reductions in urea and creatinine levels in serum were observed after 4 weeks of chitosan ingestion. The feeling of physical strength, the appetite and the sleep of patients in the treatment group had improved significantly after 12 weeks of ingestion, compared with those of patients in the control group. During the treatment period, no clinically problematic symptoms were observed. These data suggest that chitosan might be effective treatment for renal failure patients, although the mechanism of the effect should be investigated further.
Administration, Oral↗
Fludarabine-mediated repair inhibition of cisplatin-induced DNA lesions in human chronic myelogenous leukemia-blast crisis K562 cells: induction of synergistic cytotoxicity independent of reversal of apoptosis resistance.
We demonstrated previously that the nucleoside of fludarabine (F-ara-A), a clinically effective agent against chronic lymphocytic leukemia and low-grade lymphoma, produces synergistic cytotoxicity against cisplatin-resistant CP2.0 human colon tumor cells when administered in combination with cisplatin. The purpose of this study was 2-fold: (i) to determine whether the synergy occurs in K562 human chronic myelogenous leukemia cells, which, unlike CP2.0 cells, are relatively resistant to drug-induced apoptosis because they express P210(bcr-abl) and (ii) to study the underlying mechanism for the synergy if the enhancement of cytotoxicity occurs in K562 cells. When K562 cells were treated with fludarabine nucleoside and cisplatin as single agents for 4 hr, IC50 values for fludarabine and cisplatin were 3.33 and 2.28 microM, respectively, as measured by a clonogenic survival assay. The simultaneous treatment of K562 cells with the two agents resulted in synergistic cell killing as determined by median-effect analysis. Such synergistic cell killing by combined cisplatin and fludarabine could not be detected in repair-deficient human xeroderma pigmentosum cell lines. Within the range of cytotoxic concentrations, fludarabine (2.5-15 microM) and cisplatin (3-30 microM) as single agents produced no detectable internucleosomal DNA fragmentation as revealed by gel electrophoresis, nor did the combination of the two drugs induce apoptotic DNA degradation. The effects of fludarabine on the repair of cisplatin-induced DNA adducts and interstrand cross-links in K562 cells were analyzed to determine their correlation with the cytotoxic synergy. The interstrand cross-links were measured by the ethidium bromide binding fluorescence assay and quantitative Southern blotting technique. Repair of the intrastrand adducts was detected with whole-cell extracts using a cisplatin-damaged plasmid as the substrate for the in vitro repair assay. Fludarabine at clinically achievable concentrations (1.5-4.5 microM fludarabine nucleoside; 20-100 microM fludarabine triphosphate) inhibited the repair of the DNA lesions induced by cisplatin in a dose-dependent fashion in K562 cells but not in xeroderma pigmentosum cells. Cotreatment with fludarabine preferentially increased the number of interstrand cross-links induced by cisplatin in actively transcribed genes in K562 cells. These data demonstrate the DNA-repair-inhibitory effect of fludarabine and suggest that this effect may contribute to the synergistic cytotoxicity of the fludarabine/cisplatin combination that resulted in decreased clonogenic survival of apoptosis-resistant K562 cells.
Antineoplastic Agents↗
Glycoprotein H-related complexes of human cytomegalovirus: identification of a third protein in the gCIII complex.
Previous studies have described three disulfide-bonded glycoprotein complexes within the envelope of human cytomegalovirus (HCMV). These have been designated gCI, gCII, and gCIII. Although gCI has been identified as homodimeric glycoprotein B (gB, gpUL55), the compositions of gCII and gCIII remain incompletely defined. Earlier studies suggested that gCIII was composed of glycoprotein H (gH, gpUL75) complexed with a second glycoprotein, the gL homolog of HCMV. We characterized the gCIII complex of HCMV using recombinant vaccinia virus-expressed gH and gL. Our results indicated that authentic gCIII was not reconstituted by coexpression of gH and gL. The presence of a third, structurally and antigenically unique glycoprotein with an estimated molecular mass of 125,000 Da in virion-derived gCIII complexes suggested that at least three proteins were necessary for formation of this envelope glycoprotein complex. This third glycoprotein, gp125, contained both simple and complex N-linked carbohydrates and had an estimated deglycosylated mass of 64,000 Da. Furthermore, we demonstrated that mature gH existed as both a covalently complexed and noncovalently associated component of the gCIII complex within the envelope of infectious extracellular virions. These findings provide further evidence for the structural complexity of the envelope of HCMV and emphasize the uncertainties associated with the previous assignment of specific functions to envelope proteins of HCMV.
Animals↗
A conditional self-inactivating retrovirus vector that uses a tetracycline-responsive expression system.
We developed a novel conditional self-inactivating (C-SIN) vector, TL-SN, by replacement of the enhancer-promoter of the 3' long terminal repeat of Moloney murine leukemia virus with a synthetic tetracycline operator-cytomegalovirus promoter (tetP) from the tetracycline-responsive expression system (TRES). The other component of the TRES, a chimeric transactivator (tTA), was stably incorporated into PA317 amphotropic packaging cells, thus generating the packaging cell line PA317-tTA. C-SIN amphotropic G418-resistant virus particles were generated with a titer of 2 x 10(5) CFU/ml within 2 days of transinfection of PA317-tTA cells with TL-SN ecotropic virus particles. This titer was approximately 2 log units higher than that obtained by transinfection of parental PA317 cells and was due to the high level of viral transcripts originating from the tetP promoter at the 5' end of the transduced vector in the presence of tTA. Our C-SIN vector has the potential for use in human gene therapy since it incorporates the advantages of previous SIN vectors in having weak tetP promoter activity (in the absence of tTA in target cells) while at the same time achieving high viral titers with PA317-tTA packaging cells.
3T3 Cells↗
Trends in growth in England and Scotland, 1972 to 1994.
AIM: To monitor the growth of 5 to 11 year old English and Scottish children from 1972 to 1994. No similar data are available from any other study. DESIGN: Mixed longitudinal. SUBJECTS: In England 7000 children were sampled in the first year, falling to 5000. In Scotland the original sample was 2000 but this was enlarged later to 3500. MAIN OUTCOME MEASUREMENTS: Height, weight, weight for height index, and triceps skinfold thickness. RESULTS: Height of English children in most age groups increased by more than 1 cm and by more than 2 cm in Scotland during the period 1972 to 1994. Triceps skinfold measurement increased by almost 8% in 7 year old English boys and by 7% in 7 year old girls. In Scotland triceps skinfold measurement increased by nearly 10% in 7 year old boys and by 11% in 7 year old girls. Weight for height index followed a similar pattern. CONCLUSION: Children in England and Scotland are becoming taller for a given age. The increases in fatness indicate an urgent need for realistic interventions for reductions in obesity in the whole population. As weight for height index is less sensitive than skinfold thickness we recommend triceps and subscapular skinfold thickness measurements for monitoring obesity in children.
Body Height↗
Effect of vitamin E supplementation on hepatic fibrogenesis in chronic dietary iron overload.
It has been suggested that lipid peroxidation plays an important role in hepatic fibrogenesis resulting from chronic iron overload. Vitamin E is an important lipid-soluble antioxidant that has been shown to be decreased in patients with hereditary hemochromatosis and in experimental iron overload. The aim of this study was to determine the effects of vitamin E supplementation on hepatic lipid peroxidation and fibrogenesis in an animal model of chronic iron overload. Rats were fed the following diets for 4, 8, or 14 mo: standard laboratory diet (control), diet with supplemental vitamin E (200 IU/kg, control + E), diet with carbonyl iron (Fe), and diet with carbonyl iron supplemented with vitamin E (200 IU/kg. Fe + E). Iron loading resulted in significant decreases in hepatic and plasma vitamin E levels at all time points, which were overcome by vitamin E supplementation. Thiobarbituric acid-reactive substances (an index of lipid peroxidation) were increased three- to fivefold in the iron-loaded livers; supplementation with vitamin E reduced these levels by at least 50% at all time points. Hepatic hydroxyproline levels were increased twofold by iron loading. Vitamin E did not affect hydroxyproline content at 4 or 8 mo but caused an 18% reduction at 14 mo in iron-loaded livers. At 8 and 14 mo, vitamin E decreased the number of alpha-smooth muscle actin-positive stellate cells in iron-loaded livers. These results demonstrate a dissociation between lipid peroxidation and collagen production and suggest that the profibrogenic action of iron in this model is mediated through effects which cannot be completely suppressed by vitamin E.
Alanine Transaminase↗
IGF-I induces collagen and IGFBP-5 mRNA in rat intestinal smooth muscle.
Insulin-like growth factor (IGF) binding protein 5 (IGFBP-5) mRNA was studied in intestines of rats with peptidoglycan-polysaccharide enterocolitis by Northern analysis and in situ hybridization. IGFBP-5 mRNA was increased 2.4 +/- 0.5-fold in inflamed rat colon compared with controls and was highly expressed in smooth muscle. Cultured rat intestinal smooth muscle cells were used to study the regulation of IGFBP-5 and type I collagen synthesis. IGF-I (100 ng/ml) increased IGFBP-5 mRNA (1.9 +/- 0.1-fold) and collagen type alpha1(I) mRNA (1.6 +/- 0.2-fold) in cultured smooth muscle cells. IGF-I induced a dose- and time-dependent increase in IGFBP-5 in conditioned medium by Western ligand blot and by immunoblot. IGF-I did not affect the IGFBP-5 mRNA decay rate after transcriptional blockade. Cycloheximide abolished IGFBP-5 mRNA. In conclusion, IGFBP-5 mRNA is expressed by intestinal smooth muscle and is increased during chronic inflammation. IGF-I increases IGFBP-5 and collagen mRNAs in intestinal smooth muscle cells.
Animals↗
A simplified method for isolation of large numbers of defined nephron segments.
We describe a simplified method for the isolation of large numbers of nephron segments from rat and rabbit kidneys. In contrast to most previous protocols, the kidneys are not perfused. After removal from the animal, the kidney is sliced and torn in pieces that are subsequently digested in culture medium containing 0.5 mg/ml of collagenase at 37 degrees C. If the preparation is agitated only very gently and infrequently, then the tissue gradually falls apart into a suspension containing long nephron fragments, often consisting of multiple connected segments. These are easily sorted into homogeneous segment populations that can be used for enzyme assays, protein extraction for immunoblotting, and RNA extraction for reverse transcription-polymerase chain reaction, all of which have been done successfully in our laboratory. For comparison, we have also examined cortical collecting tubule segments and cells prepared by the more rigorous protocol described previously (E. Schlatter, U. Fröbe, and R. Greger. Pflügers Arch. 421: 381-387, 1992). Even after the isolation of single cells in a Ca2+-free medium, the cells maintain their normal architecture and a distinct separation of apical and basolateral membranes.
Animals↗
GABA receptors of bipolar cells from the skate retina: actions of zinc on GABA-mediated membrane currents.
GABA receptors of bipolar cells from the skate retina: actions of zinc on GABA-mediated membrane currents. J. Neurophysiol. 78: 2402-2412, 1997. gamma-Aminobutyric acid (GABA)-induced currents were recorded from isolated bipolar cells of the skate retina using perforated patch-clamp methodology. Pharmacological analysis of the responses, using selective agonists and antagonists of the major classes of GABA receptor, revealed the presence of both GABAA and GABAC receptors at both the dendrites and axon terminals of the bipolar cells. The two receptor types showed very different reactions to zinc, a divalent metallic cation that was detected in the synaptic terminal region of skate photoreceptors. Currents mediated by the activation of GABAC receptors were down-regulated by zinc, a feature that is typical of the action of zinc on GABAC receptors. On the other hand, the effects of zinc on GABAA receptor-mediated activity was highly dependent on zinc concentration. Unlike the GABAA receptors on other neurons, responses mediated by activation of the GABAA receptor of skate bipolar cells were significantly enhanced by zinc concentrations in the range of 0. 1-100 mu M; at higher concentrations of zinc (>100 mu M), response amplitudes were suppressed below control levels. The enhancement of GABAA receptor activity on skate bipolar cells showed little voltage dependence, suggesting that zinc is acting on the extracellular domain of the GABAA receptor. In the presence of 10 mu M zinc, the dose-response curve for 4,5,6, 7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP; a GABAA agonist that suppresses GABAC-activated currents) was shifted to the left of the curve obtained in the absence of zinc, but without a significant change in the response maximum. This finding indicates that the enhancing effect of zinc is due primarily to its ability to increase the sensitivity of the GABAA receptor. The novel enhancement of neuronal GABAA receptor activity by zinc, observed previously in the GABAA-mediated responses of skate Müller (glial) cells, may reflect the presence of a unique subtype of GABAA receptor on the bipolar and Müller cells of the skate retina.
Animals↗