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Smith CA, Ganschow PS, Reilly BM, Evans AT, McNutt RA, Osei A, Saquib M, Surabhi S, Yadav S. Teaching residents evidence-based medicine skills: a controlled trial of effectiveness and assessment of durability. J Gen Intern Med 2000; 15:710-5. [PMID: 11089714 PMCID: PMC1495601 DOI: 10.1046/j.1525-1497.2000.91026.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES To measure the effectiveness of an educational intervention designed to teach residents four essential evidence-based medicine (EBM) skills: question formulation, literature searching, understanding quantitative outcomes, and critical appraisal. DESIGN Firm-based, controlled trial. SETTING Urban public hospital. PARTICIPANTS Fifty-five first-year internal medicine residents: 18 in the experimental group and 37 in the control group. INTERVENTION An EBM course, taught 2 hours per week for 7 consecutive weeks by senior faculty and chief residents focusing on the four essential EBM skills. MEASUREMENTS AND MAIN RESULTS The main outcome measure was performance on an EBM skills test that was administered four times over 11 months: at baseline and at three time points postcourse. Postcourse test 1 assessed the effectiveness of the intervention in the experimental group (primary outcome]; postcourse test 2 assessed the control group after it crossed over to receive the intervention; and postcourse test 3 assessed durability. Baseline EBM skills were similar in the two groups. After receiving the EBM course, the experimental group achieved significantly higher postcourse test scores (adjusted mean difference, 21%; 95% confidence interval, 13% to 28%; P < .001). Postcourse improvements were noted in three of the four EBM skill domains (formulating questions, searching, and quantitative understanding [P < .005 for all], but not in critical appraisal skills [P = .4]). After crossing over to receive the educational intervention, the control group achieved similar improvements. Both groups sustained these improvements over 6 to 9 months of follow-up. CONCLUSIONS A brief structured educational intervention produced substantial and durable improvements in residents' cognitive and technical EBM skills.
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Sheng Y, Sun X, Shen Y, Bognar AL, Baker EN, Smith CA. Structural and functional similarities in the ADP-forming amide bond ligase superfamily: implications for a substrate-induced conformational change in folylpolyglutamate synthetase. J Mol Biol 2000; 302:427-40. [PMID: 10970743 DOI: 10.1006/jmbi.2000.3987] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Comparison of the three-dimensional structures of folylpolyglutamate synthetase (FPGS) and the bacterial cell wall ligase UDP-N-acetylmuramoyl-l-alanine:d-glutamate ligase (MurD) reveals that these two enzymes have a remarkable structural similarity despite a low level of sequence identity. Both enzymes have a modular, multi-domain structure and catalyse a similar ATP-dependent reaction involving the addition of a glutamate residue to a carboxylate-containing substrate, tetrahydrofolate in the case of FPGS, and UDP-N-acetylmuramoyl-l-alanine in the case of MurD. Site-directed mutations of selected residues in the active site of Lactobacillus casei FPGS (P74A, E143A, E143D, E143Q, K185A, D313A, H316A, G411A and S412A) showed that most of these changes resulted in an almost complete loss of activity. Several of these amino acid residues in FPGS are found in structurally equivalent positions to active-site residues in MurD. Some insights into the function of these residues in FPGS activity are proposed, based on the roles surmised from the structures of two MurD. UDP-N-acetylmuramoyl-l-alanine.ADP complexes and a MurD. UDP-N-acetylmuramoyl-l-alanine-d-glutamate complex. Furthermore, the comparison has led us to propose that conformational changes induced by substrate binding in the reaction mechanism of FPGS result in a movement of the domains towards each other to more closely resemble the orientation of the corresponding domains in MurD. This relative domain movement may be a key feature of this new family of ADP-forming amide bond ligases.
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Lan N, Rooney BL, Lee SW, Howrey RP, Smith CA, Sullenger BA. Enhancing RNA repair efficiency by combining trans-splicing ribozymes that recognize different accessible sites on a target RNA. Mol Ther 2000; 2:245-55. [PMID: 10985955 DOI: 10.1006/mthe.2000.0125] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recent reports have demonstrated that trans-splicing ribozymes can be employed to repair mutant RNAs. One key factor that influences RNA repair efficiency is the accessibility of the substrate RNA for ribozyme binding, which is complicated by the fact that RNAs may assume multiple conformations and have proteins bound to them in vivo. Here we describe a strategy to map accessible sites on sickle beta-globin (beta(s)-globin) transcripts in vitro and in vivo and to use this information to enhance RNA repair efficiency. Two sites upstream of the sickle mutation were identified as accessible in some fraction of the beta-globin RNA by mapping with a ribozyme library and the accessibility of those sites was assessed by in vitro cleavage analyses. Ribozymes targeting either site could only convert a certain fraction of the beta(s)-globin RNA to product but not drive the reaction to completion. However, cleavage and splicing reactions were driven further toward completion when the two ribozymes were both added to the reactions, suggesting that the substrate RNA is present in multiple conformations in vitro. These two ribozymes were each able to repair beta(s)-globin transcripts in erythrocyte precursors derived from peripheral blood from individuals with sickle cell disease. Moreover, the relative accessibility of the targeted sites in vivo is as predicted by mapping and in vitro analyses. These results demonstrate that this novel RNA mapping strategy represents an effective means to determine the accessible regions of target RNAs and that combinations of trans-splicing ribozymes can be employed to enhance RNA repair efficiency of clinically relevant transcripts such as beta(s)-globin RNA.
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Toogood HS, Smith CA, Baker EN, Daniel RM. Purification and characterization of Ak.1 protease, a thermostable subtilisin with a disulphide bond in the substrate-binding cleft. Biochem J 2000; 350 Pt 1:321-8. [PMID: 10926860 PMCID: PMC1221258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Ak.1 protease, a thermostable subtilisin isolated originally from Bacillus st. Ak.1, was purified to homogeneity from the Escherichia coli clone PB5517. It is active against substrates containing neutral or hydrophobic branched-chain amino acids at the P(1) site, such as valine, alanine or phenylalanine. The K(m) and k(cat) of the enzyme decrease with decreasing temperature, though not to the same degree with all substrates, suggesting that specificity changes with temperature. The protease is markedly stabilized by Ca(2+) ions. At 70 degrees C, a 10-fold increase in Ca(2+) concentration increases the half-life by three orders of magnitude. Ak.1 protease is stabilized by Ca(2+) to a greater extent than is thermitase. This may be due, in part, to the presence of an extra Ca(2+)-binding site in Ak.1 protease. Other metal ions, such as Sr(2+), increase the thermostability of the enzyme, but to a significantly lower degree than does Ca(2+). The structure of the protease showed the presence of a disulphide bond located within the active-site cleft. This bond influences both enzyme activity and thermostability. The disulphide bond appears to have a dual role: maintaining the integrity of the substrate-binding cleft and increasing the thermostability of the protease. The protease was originally investigated to determine its usefulness in the clean-up of DNA at high temperatures. However, it was found that this protease has a limited substrate specificity, so this application was not explored further.
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Liu SK, Smith CA, Arnold R, Kiefer F, McGlade CJ. The adaptor protein Gads (Grb2-related adaptor downstream of Shc) is implicated in coupling hemopoietic progenitor kinase-1 to the activated TCR. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:1417-26. [PMID: 10903746 DOI: 10.4049/jimmunol.165.3.1417] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The hemopoietic-specific Gads (Grb2-related adaptor downstream of Shc) adaptor protein possesses amino- and carboxyl-terminal Src homology 3 (SH3) domains flanking a central SH2 domain and a unique region rich in glutamine and proline residues. Gads functions to couple the activated TCR to distal signaling events through its interactions with the leukocyte-specific signaling proteins SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa) and LAT (linker for activated T cells). Expression library screening for additional Gads-interacting molecules identified the hemopoietic progenitor kinase-1 (HPK1), and we investigated the HPK1-Gads interaction within the DO11.10 murine T cell hybridoma system. Our results demonstrate that HPK1 inducibly associates with Gads and becomes tyrosine phosphorylated following TCR activation. HPK1 kinase activity is up-regulated in response to activation of the TCR and requires the presence of its proline-rich motifs. Mapping experiments have revealed that the carboxyl-terminal SH3 domain of Gads and the fourth proline-rich region of HPK1 are essential for their interaction. Deletion of the fourth proline-rich region of HPK1 or expression of a Gads SH2 mutant in T cells inhibits TCR-induced HPK1 tyrosine phosphorylation. Together, these data suggest that HPK1 is involved in signaling downstream from the TCR, and that SH2/SH3 domain-containing adaptor proteins, such as Gads, may function to recruit HPK1 to the activated TCR complex.
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Smith CA, Henderson VW, McCleary CA, Murdock GA, Buckwalter JG. Anosognosia and Alzheimer's disease: the role of depressive symptoms in mediating impaired insight. J Clin Exp Neuropsychol 2000; 22:437-44. [PMID: 10923053 DOI: 10.1076/1380-3395(200008)22:4;1-0;ft437] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The relation between anosognosia and dementia severity in Alzheimer's disease (AD) has been unclear. We constructed a measure that quantified the difference between the perceptions of deficits of patients with AD (n = 23) and ratings from a knowledgeable informant as a measure of anosognosia. There was no correlation between dementia severity and anosognosia. However, dementia severity was positively correlated with the degree of anosognosia after controlling for depressive symptomatology (p =.03). Post-hoc analyses, also controlling for depressive symptoms, indicated that higher levels of anosognosia were associated with lower performance on specific cognitive tasks. These results suggest depressive symptoms may confound the relationship between anosognosia and dementia severity.
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Eastwood PR, Curran AK, Smith CA, Dempsey JA. Hemodynamic effects of pressures applied to the upper airway during sleep. J Appl Physiol (1985) 2000; 89:537-48. [PMID: 10926636 DOI: 10.1152/jappl.2000.89.2.537] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The increase in systemic blood pressure after an obstructive apnea is due, in part, to sympathetically mediated vasoconstriction. We questioned whether upper airway (UA) receptors could contribute reflexly to this vasoconstriction. Four unanesthetized dogs were studied during wakefulness and non-rapid-eye-movement (NREM) sleep. The dogs breathed via a fenestrated tracheostomy tube sealed around the tracheal stoma. The snout was sealed with an airtight mask, thereby isolating the UA when the fenestration was closed and exposing the UA to negative inspiratory intrathoracic pressure when it was open. The blood pressure response to three UA perturbations was studied: 1) square-wave negative pressures sufficient to cause UA collapse with the fenestration closed during a mechanical hyperventilation-induced central apnea; 2) tracheal occlusion with the fenestration open vs. closed; and 3) high-frequency pressure oscillations (HFPO) with the fenestration closed. During NREM sleep, 1) blood pressure response to tracheal occlusion was similar with the fenestration open or closed; 2) collapsing the UA with negative pressures failed to alter blood pressure during a central apnea; and 3) application of HFPO to the UA during eupnea and resistive-loaded breaths increased heart rate and blood pressure. However, these changes were likely to be secondary to the effects of HFPO-induced reflex changes on prolonging expiratory time. These findings suggest that activation of UA pressure-sensitive receptors does not contribute directly to the pressor response associated with sleep-disordered breathing events.
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Smith CA, Khoury JM, Shields SM, Roper GJ, Duffy RE, Edelhauser HF, Lubniewski AJ. Unexpected corneal endothelial cell decompensation after intraocular surgery with instruments sterilized by plasma gas. Ophthalmology 2000; 107:1561-6; discussion 1567. [PMID: 10919908 DOI: 10.1016/s0161-6420(00)00174-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Ten cases of unexpected corneal endothelial cell decompensation occurring after routine intraocular surgery using instruments sterilized with a new plasma gas protocol are described. DESIGN A retrospective observational case series with 1 year of follow-up was conducted. RESULTS All patients had corneal decompensation and nonreactive pupils after surgery. Six patients required penetrating keratoplasty. Three patients partially recovered pupillary function. Visual acuity at 1 year ranged from 20/20 to hand motion (HM). One patient with an anterior chamber intraocular lens (ACIOL) experienced optic atrophy and HM vision despite resolution of corneal edema. CONCLUSIONS Toxic corneal endothelial cell destruction syndrome was associated with the introduction of plasma gas sterilization protocols.
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Smith CA. Ethical concerns about communicators. J Am Vet Med Assoc 2000; 216:1713-4. [PMID: 10844957 DOI: 10.2460/javma.2000.216.1713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Curran AK, Rodman JR, Eastwood PR, Henderson KS, Dempsey JA, Smith CA. Ventilatory responses to specific CNS hypoxia in sleeping dogs. J Appl Physiol (1985) 2000; 88:1840-52. [PMID: 10797149 DOI: 10.1152/jappl.2000.88.5.1840] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our study was concerned with the effect of brain hypoxia on cardiorespiratory control in the sleeping dog. Eleven unanesthetized dogs were studied; seven were prepared for vascular isolation and extracorporeal perfusion of the carotid body to assess the effects of systemic [and, therefore, central nervous system (CNS)] hypoxia (arterial PO(2) = 52, 45, and 38 Torr) in the presence of a normocapnic, normoxic, and normohydric carotid body during non-rapid eye movement sleep. A lack of ventilatory response to systemic boluses of sodium cyanide during carotid body perfusion demonstrated isolation of the perfused carotid body and lack of other significant peripheral chemosensitivity. Four additional dogs were carotid body denervated and exposed to whole body hypoxia for comparison. In the sleeping dog with an intact and perfused carotid body exposed to specific CNS hypoxia, we found the following. 1) CNS hypoxia for 5-25 min resulted in modest but significant hyperventilation and hypocapnia (minute ventilation increased 29 +/- 7% at arterial PO(2) = 38 Torr); carotid body-denervated dogs showed no ventilatory response to hypoxia. 2) The hyperventilation was caused by increased breathing frequency. 3) The hyperventilatory response developed rapidly (<30 s). 4) Most dogs maintained hyperventilation for up to 25 min of hypoxic exposure. 5) There were no significant changes in blood pressure or heart rate. We conclude that specific CNS hypoxia, in the presence of an intact carotid body maintained normoxic and normocapnic, does not depress and usually stimulates breathing during non-rapid eye movement sleep. The rapidity of the response suggests a chemoreflex meditated by hypoxia-sensitive respiratory-related neurons in the CNS.
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Pagé DE, Smith CA. The importance of an extra hour of cycler therapy to obtain better adequacy. ADVANCES IN PERITONEAL DIALYSIS. CONFERENCE ON PERITONEAL DIALYSIS 2000; 15:144-6. [PMID: 10682090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
As continuous ambulatory peritoneal dialysis (CAPD) patients lose residual renal function, it frequently becomes impossible from them to obtain adequate dialysis unless the dialysis prescription is changed. Increasing the dwell volumes, increasing the frequency of exchanges, and using a night-exchange device or a cycler are the means available to improve adequacy. In an effort to obtain dialysis adequacy, we studied how an extra hour on cycler therapy can contribute to improving dialysis adequacy. Over 18 months, we optimized solute clearance using the PD Adequest program (Baxter Healthcare Corporation, Chicago, Illinois, U.S.A.) in 70 patients. After finding the best total cycler volume, we compared the weekly creatinine clearance and weekly Kt/V from 8-hour cycler therapy to that from 9-hour cycler therapy for the four types of membrane transport. Adding one extra hour on cycler therapy improved weekly creatinine clearance by 3-6.5 L and the weekly Kt/V by 0.16-0.20. When patients are marginally approaching the required weekly Kt/V or creatinine clearance, an extra hour on the cycler may help to achieve the desired adequacy.
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Wong NA, Rae F, Bathgate A, Smith CA, Harrison DJ. Polymorphisms of the gene for microsomal epoxide hydrolase and susceptibility to alcoholic liver disease and hepatocellular carcinoma in a Caucasian population. Toxicol Lett 2000; 115:17-22. [PMID: 10817627 DOI: 10.1016/s0378-4274(00)00166-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The gene encoding the xenobiotic-metabolising microsomal enzyme, epoxide hydrolase (mEPHX), shows two common mutations, i.e. at exons 3 and 4. It is unknown how these genetic polymorphisms relate to risk of developing alcoholic liver disease (ALD) and/or hepatocellular carcinoma (HCC) in a Caucasian population. DNA samples extracted from the blood of 61 ALD patients and 203 healthy controls, and from archival liver tissue of 46 cases of HCC, were subjected to polymerase chain reaction amplification followed by digestion with EcoR V or Rsa I to demonstrate polymorphisms of exon 3 or 4, respectively. The distributions of the genotypes of exon 3 in the ALD and HCC patients, and exon 4 in the HCC patients did not differ significantly from those of the control group. However, compared with the control group, the ALD group contained a significantly greater number of individuals homozygous or heterozygous for the exon 4 mutation. This suggested association between possession of the exon 4 mutant mEPHX allele and increased risk of developing ALD may relate to known interactions between mEPHX and alcohol-metabolising enzyme systems, or to linkage disequilibrium between the mutation and other genetic risk factors for ALD.
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Guite JW, Walker LS, Smith CA, Garber J. Children's perceptions of peers with somatic symptoms: the impact of gender, stress, and illness. J Pediatr Psychol 2000; 25:125-35. [PMID: 10780139 DOI: 10.1093/jpepsy/25.3.125] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVE To investigate how illness characteristics influence children's responses to ill peers. METHODS A sample of 363 4th and 5th graders responded to a vignette describing a peer with abdominal pain. In a 2 x 2 x 2 x 2 design, conditions varied by (a) evidence for organic disease, (b) presence of stress, (c) sex of vignette character, and (d) sex of respondent. Children rated symptom severity, liking for the peer, and whether the peer should be excused from normal responsibilities. RESULTS Same sex preferences significantly influenced children's liking for a peer. Children viewed symptoms with an organic etiology as more severe than those without one. Under certain conditions, symptom severity judgments mediated the relation between the presence of organic disease and (a) liking and (b) granting relief from responsibility. The presence of stress had little effect on ratings of symptom severity, liking, or relief from responsibility. CONCLUSIONS Gender and evidence of organic disease influence children's perceptions of and responses to symptomatic peers.
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Smith CA, Witherow R. The assessment of female pelvic floor dysfunction. BJU Int 2000; 85:611-3. [PMID: 10735937 DOI: 10.1046/j.1464-410x.2000.00618-6.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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MacGillivray RT, Bewley MC, Smith CA, He QY, Mason AB, Woodworth RC, Baker EN. Mutation of the iron ligand His 249 to Glu in the N-lobe of human transferrin abolishes the dilysine "trigger" but does not significantly affect iron release. Biochemistry 2000; 39:1211-6. [PMID: 10684598 DOI: 10.1021/bi991522y] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Serum transferrin is the major iron transport protein in humans. Its function depends on its ability to bind iron with very high affinity, yet to release this bound iron at the lower intracellular pH. Possible explanations for the release of iron from transferrin at low pH include protonation of a histidine ligand and the existence of a pH-sensitive "trigger" involving a hydrogen-bonded pair of lysines in the N-lobe of transferrin. We have determined the crystal structure of the His249Glu mutant of the N-lobe half-molecule of human transferrin and compared its iron-binding properties with those of the wild-type protein and other mutants. The crystal structure, determined at 2.4 A resolution (R-factor 19.8%, R(free) 29.4%), shows that Glu 249 is directly bound to iron, in place of the His ligand, and that a local movement of Lys 296 has broken the dilysine interaction. Despite the loss of this potentially pH-sensitive interaction, the H249E mutant is only slightly more acid-stable than wild-type and releases iron slightly faster. We conclude that the loss of the dilysine interaction does make the protein more acid stable but that this is counterbalanced by the replacement of a neutral ligand (His) by a negatively charged one (Glu), thus disrupting the electroneutrality of the binding site.
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Drake EB, Henderson VW, Stanczyk FZ, McCleary CA, Brown WS, Smith CA, Rizzo AA, Murdock GA, Buckwalter JG. Associations between circulating sex steroid hormones and cognition in normal elderly women. Neurology 2000; 54:599-603. [PMID: 10680789 DOI: 10.1212/wnl.54.3.599] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To provide exploratory analyses of associations between levels of several sex hormones and cognitive performance in elderly women. BACKGROUND Sex steroid hormones are implicated in the cognitive processes of the adult brain. Comparing cognitive performance across or between conditions associated with different hormone levels, such as phases of the menstrual cycle, surgical menopause, and estrogen replacement therapy suggests conditions with higher levels of estrogen are associated with better verbal memory and possibly worse visuospatial ability. METHOD The authors measured circulating sex hormone levels in 39 highly educated, nondemented, predominantly white elderly women. Levels were correlated with neuropsychological performance, controlling for age, education, frequency of prior testing, use of estrogen replacement, and depression. RESULTS High estradiol levels were associated with better delayed verbal memory and retrieval efficiency, whereas low levels were associated with better immediate and delayed visual memory. Levels of testosterone were related positively to verbal fluency. Levels of progesterone and androstenedione were unrelated to cognitive performance. CONCLUSIONS Both estrogen and testosterone showed associations with cognitive performance. Estrogen may enhance, and depress, specific cognitive skills.
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Smith CA, Clifford V, Western PS, Wilcox SA, Bell KS, Sinclair AH. Cloning and expression of a DAX1 homologue in the chicken embryo. J Mol Endocrinol 2000; 24:23-32. [PMID: 10656994 DOI: 10.1677/jme.0.0240023] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
DAX1 is an unusual member of the orphan nuclear receptor family of transcription factors. Mutations in human DAX1 cause X-linked adrenal hypoplasia congenita, while abnormal duplication of the gene is responsible for male-to-female dosage-sensitive sex reversal. Based on these and other observations, DAX1 is thought to play a role in adrenal and gonadal development in mammals. As DAX1 has not previously been described in any other vertebrate, a putative avian DAX1 clone was isolated from an embryonic chicken (Gallus domesticus) urogenital ridge cDNA library. The expression profile of this cDNA was then examined during gonadogenesis. The clone included the conserved 3' ligand-binding motif identified in humans and mice but the 5' region lacked the repeat motif thought to specify a DNA-binding domain in mammals. Southern blot analysis and fluorescence in situ hybridisation mapping showed that the gene is autosomal, located on chromosome 1q. Sequence comparisons showed that the putative chicken DAX1 protein has 63 and 60% identity with the human and mouse proteins respectively over the region of the conserved ligand-binding domain. However, stronger identity (74%) exists with a putative alligator DAX1 sequence over the same region. Northern blotting detected a single 1.4 kb transcript in late embryonic chicken gonads, while RNase protection assays revealed expression in the embryonic gonads of both sexes during the period of sexual differentiation. Expression increased in both sexes during gonadogenesis, but was higher in females than in males. This is the first description of a DAX1 homologue in a non-mammalian vertebrate.
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Smith CA, Sinclair AH. The cell biology and molecular genetics of testis determination. Results Probl Cell Differ 2000; 28:23-52. [PMID: 10626293 DOI: 10.1007/978-3-540-48461-5_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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120
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Camacho O, Smith CA. Sliding mode control: an approach to regulate nonlinear chemical processes. ISA TRANSACTIONS 2000; 39:205-218. [PMID: 10871215 DOI: 10.1016/s0019-0578(99)00043-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A new approach for the design of sliding mode controllers based on a first-order-plus-deadtime model of the process, is developed. This approach results in a fixed structure controller with a set of tuning equations as a function of the characteristic parameters of the model. The controller performance is judged by simulations on two nonlinear chemical processes.
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Smith CA, Pollice AA, Gu LP, Brown KA, Singh SG, Janocko LE, Johnson R, Julian T, Hyams D, Wolmark N, Sweeney L, Silverman JF, Shackney SE. Correlations among p53, Her-2/neu, and ras overexpression and aneuploidy by multiparameter flow cytometry in human breast cancer: evidence for a common phenotypic evolutionary pattern in infiltrating ductal carcinomas. Clin Cancer Res 2000; 6:112-26. [PMID: 10656439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Human solid tumors develop multiple genetic abnormalities that accumulate progressively in individual cells during the course of tumor evolution. We sought to determine whether there are specific sequences of occurrence of these progressive evolutionary changes in human breast cancers by performing correlated cell-by-cell measurements of cell DNA content, p53 protein, Her-2/neu protein, and ras protein by multiparameter flow cytometry in 56 primary tumor samples obtained at surgery. In addition, p53 allelic loss and Her-2/neu gene amplification were determined by fluorescence in situ hybridization in cells from the same samples. We reasoned that if there is a specific order in which genetic changes occur, the same early changes would be found consistently in the cells with the fewest abnormalities. We reasoned further that late-developing abnormalities would not occur alone in individual cells but would almost always be found together with the early changes inherited by the same cells. By these criteria, abnormalities involving p53 generally occurred early in the course of development of invasive breast cancers, whereas ras protein overexpression was found to be a late-occurring phenomenon. Within individual tumors, cellular p53 overexpression was often observed alone in individual cells, whereas ras protein overexpression was rarely observed in the absence of p53 overexpression and/or Her-2/neu overexpression in the same cells. Furthermore, the intracellular level of each abnormally expressed protein was found to increase progressively as new abnormalities were acquired. Infiltrating ductal carcinomas exhibited characteristic phenotypic patterns in which p53 allelic loss and/or p53 protein overexpression, Her-2/neu amplification and/or overexpression, aneuploidy, and ras overexpression accumulated within individual cells. However, this pattern was not a prominent feature of lobular breast cancers. All six lobular breast cancers studied were diploid. p53 allelic loss and/or early p53 overexpression, and late ras cooverexpression in the same cells were less common in lobular breast cancers than in infiltrating ductal carcinomas. Although Her-21neu overexpression was a common finding in lobular breast cancers, Her-2/neu amplification was not observed in these tumors.
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MESH Headings
- Aneuploidy
- Breast Neoplasms/genetics
- Breast Neoplasms/pathology
- Breast Neoplasms/therapy
- Carcinoma, Ductal, Breast/genetics
- Carcinoma, Ductal, Breast/pathology
- Carcinoma, Ductal, Breast/therapy
- DNA, Neoplasm/analysis
- Diploidy
- Female
- Flow Cytometry
- Genes, erbB-2
- Genes, p53
- Genes, ras
- Humans
- Loss of Heterozygosity
- Phenotype
- Receptor, ErbB-2/analysis
- Receptors, Estrogen/analysis
- Receptors, Progesterone/analysis
- Tumor Suppressor Protein p53/analysis
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Smith CA, Toogood HS, Baker HM, Daniel RM, Baker EN. Calcium-mediated thermostability in the subtilisin superfamily: the crystal structure of Bacillus Ak.1 protease at 1.8 A resolution. J Mol Biol 1999; 294:1027-40. [PMID: 10588904 DOI: 10.1006/jmbi.1999.3291] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Proteins of the subtilisin superfamily (subtilases) are widely distributed through many living species, where they perform a variety of processing functions. They are also used extensively in industry. In many of these enzymes, bound calcium ions play a key role in protecting against autolysis and thermal denaturation. We have determined the crystal structure of a highly thermostable protease from Bacillus sp. Ak.1 that is strongly stabilized by calcium. The crystal structure, determined at 1.8 A resolution (R=0. 182, Rfree=0.247), reveals the presence of four bound cations, three Ca(2+) and one Na(+). Two of the Ca(2+) binding sites, Ca-1 and Ca-2, correspond to sites also found in thermitase and the mesophilic subtilisins. The third calcium ion, however, is at a novel site that is created by two key amino acid substitutions near Ca-1, and has not been observed in any other subtilase. This site, acting cooperatively with Ca-1, appears to give substantially enhanced thermostability, compared with thermitase. Comparisons with the mesophilic subtilisins also point to the importance of aromatic clusters, reduced hydrophobic surface and constrained N and C termini in enhancing the thermostability of thermitase and Ak.1 protease. The Ak.1 protease also contains an unusual Cys-X-Cys disulfide bridge that modifies the active site cleft geometry.
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Smith CA, McClive PJ, Western PS, Reed KJ, Sinclair AH. Conservation of a sex-determining gene. Nature 1999; 402:601-2. [PMID: 10604464 DOI: 10.1038/45130] [Citation(s) in RCA: 285] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Lowe HJ, Antipov I, Hersh W, Smith CA, Mailhot M. Automated semantic indexing of imaging reports to support retrieval of medical images in the multimedia electronic medical record. Methods Inf Med 1999; 38:303-7. [PMID: 10805018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
This paper describes preliminary work evaluating automated semantic indexing of radiology imaging reports to represent images stored in the Image Engine multimedia medical record system at the University of Pittsburgh Medical Center. The authors used the SAPHIRE indexing system to automatically identify important biomedical concepts within radiology reports and represent these concepts with terms from the 1998 edition of the U.S. National Library of Medicine's Unified Medical Language System (UMLS) Metathesaurus. This automated UMLS indexing was then compared with manual UMLS indexing of the same reports. Human indexing identified appropriate UMLS Metathesaurus descriptors for 81% of the important biomedical concepts contained in the report set. SAPHIRE automatically identified UMLS Metathesaurus descriptors for 64% of the important biomedical concepts contained in the report set. The overall conclusions of this pilot study were that the UMLS metathesaurus provided adequate coverage of the majority of the important concepts contained within the radiology report test set and that SAPHIRE could automatically identify and translate almost two thirds of these concepts into appropriate UMLS descriptors. Further work is required to improve both the recall and precision of this automated concept extraction process.
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Kahler SC, Smith CA. AABP conference delivers relevant-CE. J Am Vet Med Assoc 1999; 215:1568-70. [PMID: 14567407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
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