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Biomedical subjects

S Young

Publications and source records attributed to S Young.

At least 73 records · Page 4Linked to original sources
PubMed2000

The role of individual lysine residues in the basic patch on turnip cytochrome f for electrostatic interactions with plastocyanin in vitro.

The role of electrostatic interactions in determining the rate of electron transfer between cytochrome f and plastocyanin has been examined in vitro with mutants of turnip cytochrome f and mutants of pea and spinach plastocyanins. Mutation of lysine residues Lys58, Lys65 and Lys187 of cytochrome f to neutral or acidic residues resulted in decreased binding constants and decreased rates of electron transfer to wild-type pea plastocyanin. Interaction of the cytochrome f mutant K187E with the pea plastocyanin mutant D51K gave a further decrease in electron transfer rate, indicating that a complementary charge pair at these positions could not compensate for the decreased overall charge on the proteins. Similar results were obtained with the interaction of the cytochrome f mutant K187E with single, double and triple mutants of residues in the acidic patches of spinach plastocyanin. These results suggest that the lysine residues of the basic patch on cytochrome f are predominantly involved in long-range electrostatic interactions with plastocyanin. However, analysis of the data using thermodynamic cycles provided evidence for the interaction of Lys187 of cytochrome f with Asp51, Asp42 and Glu43 of plastocyanin in the complex, in agreement with a structural model of a cytochrome f-plastocyanin complex determined by NMR.

Aspartic Acid↗
PubMed2000

Incidence and outcome of poststroke urinary retention: a prospective study.

OBJECTIVE: To document the incidence and outcome of poststroke urinary retention, and to determine clinical variables associated with it. DESIGN: Cohort of 80 consecutive patients. SETTING: Inpatient setting of a tertiary rehabilitation center. PARTICIPANTS: Eighty patients (48 men, 32 women; mean age, 65.4 yr) with a first ischemic stroke, admitted for rehabilitation within 4 weeks of the stroke. MAIN OUTCOME MEASURES: Patients had their postvoid residuals (PVR) assessed via a bladder scanner within 72 hours of admission. Urinary retention was defined by a PVR of more than 100mL on 2 consecutive occasions. RESULTS: Urinary retention was present in 23 (29%) patients. Cognitive impairment, aphasia, diabetes mellitus, and cortical stroke were present in 30%, 29%, 31%, and 41% of patients, respectively. Fifteen (19%) patients developed urinary tract infection during rehabilitation. Urinary retention was significantly associated (p < .05) with cognitive impairment, diabetes mellitus, aphasia, a lower admission functional status (as measured on the modified Barthel index), and urinary tract infection, but not with the use of anticholinergic medications. On discharge, 4 patients still had urinary retention (3 were voiding spontaneously and the other used intermittent catheterization). CONCLUSION: Urinary retention was common in patients with ischemic stroke. It should be strongly suspected in patients with aphasia, cognitive impairment, poor functional status, and diabetes mellitus.

Age Distribution↗
PubMed2000

Preclinical pharmacology of desloratadine, a selective and nonsedating histamine H1 receptor antagonist. 1st communication: receptor selectivity, antihistaminic activity, and antiallergenic effects.

Desloratadine (descarboethoxyloratadine, CAS 100643-71-8) is an active metabolite of loratadine (CAS 79794-75-5) that exhibits qualitatively similar pharmacodynamic activity with a relative oral potency in animals 2.5-4 times greater than loratadine. Its antihistaminic effect lasts 24 h. Desloratadine was shown to be a selective H1 antagonist with more potent antihistaminic activity in vitro than either loratadine or terfenadine (CAS 50679-08-8), as indicated by its displacement of 3H-mepyramine from H1 receptors in rat brain, guinea pig brain, and guinea pig lung, and by its antagonism of histamine-induced contractions of guinea pig ileum. Antihistaminic activity and anitallergic effects also were observed in vivo. After oral administration, desloratadine was 2.5 to 4 times more potent than loratadine in protecting against histamine-induced lethality in the guinea pig and paw edema in the mouse; after topical administration, it was almost 10 times more potent in antagonizing histamine-induced increases in nasal microvascular permeability in the guinea pig. Histamine-induced changes in pulmonary resistance and compliance were also prevented by oral administration of desloratadine and loratadine in the monkey. An oral antiallergic effect was demonstrated by important reductions of acute bronchospasm in the allergic monkey and potent inhibition of allergic cough in the guinea pig. These preclinical studies provide evidence that desloratadine is an antihistaminic agent with a greater potency than loratadine and, together with results from numerous published studies, suggest an antiallergic effect of desloratadine.

Animals↗
PubMed2000

Risk factors for acquisition of vancomycin-resistant enterococci among patients on a renal ward during a community hospital outbreak.

BACKGROUND: During an outbreak of vancomycin-resistant enterococcal (VRE) infection and colonization at a community hospital in Indianapolis, Indiana, we performed a case-control study of patients on the hospital's renal unit to determine risk factors for acquisition of VRE among this potentially high-risk patient population. METHODS: Twenty-four renal patients with VRE colonization/infection (ie, case-patients) were compared by univariate and multivariate analyses with 29 renal patients with nosocomially acquired vancomycin-susceptible enterococcal infection and colonization (ie, controls). RESULTS: Age and length of hospitalization were similar between the VRE case-patients and the vancomycin-susceptible enterococcal control-patients, but case-patients had higher Acute Physiology and Chronic Health Evaluation II scores and received significantly greater numbers of antimicrobials and significantly more days of antimicrobials during the 60 days preceding the first positive enterococcal culture. In an assessment of the appropriateness of vancomycin use, one third of vancomycin orders were found to be inappropriate in both patient groups. CONCLUSIONS: Our data show that among renal patients, those who are severely ill and receive multiple and prolonged courses of antimicrobials are at greatest risk for acquiring VRE infection or colonization. The Centers for Disease Control and Prevention recommends that hospitals develop a comprehensive plan to prevent and control infection and colonization of patients with VRE. This plan should include prompt identification of affected patients, initiation of isolation precautions to prevent patient-to-patient transmission of VRE, and prudent use of antimicrobials, including vancomycin.

APACHE↗
PubMed2000

A self-learning predictive model of articulator movements during speech production.

A model is presented which predicts the movements of flesh points on the tongue, lips, and jaw during speech production, from time-aligned phonetic strings. Starting from a database of x-ray articulator trajectories, means and variances of articulator positions and curvatures at the midpoints of phonemes are extracted from the data set. During prediction, the amount of articulatory effort required in a particular phonetic context is estimated from the relative local curvature of the articulator trajectory concerned. Correlations between position and curvature are used to directly predict variations from mean articulator positions due to coarticulatory effects. Use of the explicit coarticulation model yields a significant increase in articulatory modeling accuracy with respect to x-ray traces, as compared with the use of mean articulator positions alone.

Adolescent↗
PubMed2000

H-NS controls pap and daa fimbrial transcription in Escherichia coli in response to multiple environmental cues.

A comparative study was completed to determine the influence of various environmental stimuli on the transcription of three different fimbrial operons in Escherichia coli and to determine the role of the histone-like protein H-NS in this environmental regulation. The fimbrial operons studied included the pap operon, which encodes pyelonephritis-associated pili (P pili), the daa operon, which encodes F1845 fimbriae, and the fan operon, which encodes K99 fimbriae. Using lacZYA transcriptional fusions within each of the fimbrial operons, we tested temperature, osmolarity, carbon source, rich medium, oxygen levels, pH, amino acids, solid medium, and iron concentration for their effects on fimbrial gene expression. Low temperature, high osmolarity, glucose as a carbon source, and rich medium repressed transcription of all three operons. High iron did not alter transcription of any of the operons tested, whereas the remaining stimuli had effects on individual operons. For the pap and daa operons, introduction of the hns651 mutation relieved the repression, either fully or partially, due to low temperature, glucose as a carbon source, rich medium, and high osmolarity. Taken together, these data indicate that there are common environmental cues that regulate fimbrial transcription in E. coli and that H-NS is an important environmental regulator for fimbrial transcription in response to several stimuli.

Bacterial Proteins↗
PubMed2000

Behavioural effects of acute tryptophan depletion in healthy male volunteers.

Acute tryptophan depletion (ATD) studies have been used to assess the role of the serotonergic system in various aspects of human behaviour. Changes in mood have already been described in selected groups of individuals submitted to ATD. The present study was a randomized, double-blind, cross-over trial designed to evaluate the effects of ATD on mood, memory, attention and induced anxiety in normal male volunteers. Twelve healthy male volunteers were submitted to two separate sessions of ATD, 1 week apart. Drinks containing either a balanced mixture of amino acids (B) or a similar mixture devoid of tryptophan (T-) were administered in each session. Mood was assessed using self-rating scales. Attention and memory were assessed using a battery of psychological tests. Anxiety induction was carried out using a simulation of public speaking. Blood levels of tryptophan were assessed before and after the B and T- drinks. Results showed that ATD markedly decreased plasma tryptophan (p < 0.0001). Mood ratings, memory and attention were not changed by the T- drink. There was no difference among the anxiety levels measured under T- or B mixtures. These data supports the notion that ATD does not change mood and cognitive function in healthy subjects.

Adult↗
PubMed2000

The association between early life lung function and wheezing during the first 2 yrs of life.

Reports have suggested that certain infants are predisposed to wheezing in the first 2 yrs of life due to abnormal lung function, prior to the first wheezing illness. The authors investigated the association between infant lung function and wheeze during the first 2 yrs of life. A cohort of 253 infants was evaluated. Respiratory function assessment was performed at 1, 6, and 12 months of age. Parental history of asthma, atopy, and maternal antenatal smoking habits were recorded. An infant was identified as having wheezed on the basis of parental report and, where possible, physician diagnosis. One hundred and sixty infants (63%) had complete diary and questionnaire information on wheeze available for analysis. Of these: 79 infants (50%) had never wheezed (NW) during the first 2 yrs of life and 81 had reported wheeze (W) (50%). Of those with a report of wheeze, the distribution through the first 2 yrs of life was; 28 during the first year of life only (Y1), 21 in the second year of life only (Y2), and 32 wheezed in both the first and second years of life (Y1&2). At the age of 1 month, prior to any lower respiratory illness, the W group had impaired lung function in comparison to the NW group. In Y1 infants, the neonatal lung function differences resolved by 12 months of age. In Y2 and Y1&2 infants lung function differences persisted throughout the first year of life. Prevalence of parental asthma and maternal antenatal smoking was increased in the W group p=0.001, p=0.008, respectively), in comparison to the NW infants. Maternal antenatal smoking prevalence was increased in the Y2 and Y1&2 infants in comparison to the NW group (p=0.04), (p=0.01), respectively. Wheezing during the first year of life is often a transient condition which improves with time. It appears to be related to early life reduced small airway calibre. Wheezing that begins or persists into the second year of life is usually associated with a different abnormality of the airways. Commencement or persistence of wheeze into the second year of life may be part of the clinical entity recognized as asthma.

Asthma↗
PubMed2000

Exotic dancing and health.

The health and safety of women who work as exotic dancers are firmly embedded within the social organization of the strip club and the broader social, economic and political context of the work of exotic dancing. Exotic dancers in this study expressed health concerns associated with: the effects of costuming and appearance requirements; dirty work environments; problems due to stigmatization, sexual harassment and assault; and police disinterest or victim blaming. The balance between benefits and hazards related to exotic dancing is influenced not only by the personal choices made by dancers, but also by the organization of the strip club and the broader context within which exotic dancing takes place.

Adolescent↗
PubMed2000

Titanic troubles?

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Attitude of Health Personnel↗
PubMed2000

Reductionism in the pursuit of nursing science: (in)congruent with nursing's core values?

Within nursing scholarship a critique has developed around the philosophy and approaches of traditional science. The central theme of this critique is that the approaches of traditional science are antithetical to nursing's commitment to a humanistic philosophy, as reflected in the premise that reductionism is incongruent with nursing's core values. Several nurse scholars, believing that nursing's humanistic philosophy should guide the research efforts of the discipline, have advocated abandonment of the reductionistic approaches of traditional science. The authors contend that adoption of such a position will have serious consequences for knowledge development in nursing and subsequently will be detrimental to the advancement of nursing practice and the discipline of nursing. They refute the premise that reductionism is incongruent with nursing's core values, argue for reductionism in nursing science, and conclude that without the pursuit of epistemological holism, the actualization of nursing's core values is in jeopardy.

Humans↗
PubMed1999

Genomic organization and chromosomal localization of the human histone deacetylase 3 gene.

Reversible acetylation of histone proteins plays a critical role in transcriptional regulation, cell cycle progression, and developmental events. The steady state of histone acetylation is controlled by the enzymatic activities of multiple histone acetyltransferases and histone deacetylases (HDACs). Three distinct human HDACs are homologous to RPD3, a yeast transcriptional regulator. We have isolated and sequenced a genomic clone for the human HDAC3 gene. This is a single-copy gene spanning a region of at least 13 kb. Determination of the intron-exon splice junctions established that the gene is encoded by 15 exons ranging in size from 56 to 657 bp. Fluorescence in situ hybridization studies localized this gene to 5q31. Double-target experiments in which both HDAC3 and the early-growth response 1 gene (EGR1), which is localized in the 5q31.2 region, were used as probes showed that the HDAC3 gene lies in region 5q31.3, immediately distal to EGR1 with respect to the centromere.

Amino Acid Sequence↗
PubMed1999

The clinical significance of antibodies to human vascular endothelial cells after cardiac transplantation.

BACKGROUND: Vascular endothelial cells are primary targets for injury during both cellular and humoral allograft rejection (AR). In cardiac transplantation, the role of humoral immunity in mediating AR has not been extensively characterized. METHODS: Antibodies against human vascular endothelial cells (AECA) were measured using a cellular ELISA developed from human umbilical vein endothelial cells in 80 consecutive patients after cardiac transplantation. The aim was to determine the incidence of AECA formation after transplantation and their association with different types of AR, graft survival, and development of cardiac allograft vasculopathy (CAV). At least eight serum samples obtained from each patient were examined for AECA and an endomyocardial biopsy was performed at regular intervals during the first year after transplantation. RESULTS: Of the 80 patients examined, 31 were AECA (+) and 49 patients were AECA (-). There were no significant differences between the AECA (+) and (-) groups when examined for age, sex, and pretransplantation ischemia time. A significant correlation was found between the presence of AECA and humoral AR (P<0.015). AECA positivity did not correlate with the presence of cellular AR or the number of rejection episodes. In addition, allograft survival at 2 years after transplantation was significantly better in the AECA (-) group compared with that in the AECA (+) group (89.8% vs. 71.0%, P<0.0004). The persistence of AECA positivity during the first year after transplantation was also associated with a significantly greater incidence of CAV when compared with the patients who were AECA (-) (25.8% vs. 14.3%, P<0.004). CONCLUSIONS: AECA may be important in the mediation of humoral AR, may decrease allograft survival, and may identify a high-risk group for CAV.

Adolescent↗
PubMed1999

Comparing the rates and the activation parameters for the forward reaction between the triplet state of zinc cytochrome c and cupriplastocyanin and the back reaction between the zinc cytochrome c cation radical and cuproplastocyanin.

This is a comparative study of the photoinduced (so-called forward) electron-transfer reaction 3Zncyt/pc(II) --> Zncyt+/pc(I), between the triplet state of zinc cytochrome c (3Zncyt) and cupriplastocyanin [pc(II)], and the thermal (so-called back) electron-transfer reaction Zncyt+/pc(I) --> Zncyt/pc(II), between the cation (radical) of zinc cytochrome c (Zncyt+) and cuproplastocyanin [pc(I)], which follows it. Both reactions occur between associated (docked) reactants, and the respective unimolecular rate constants are kF and kB. Our previous studies showed that the forward reaction is gated by a rearrangement of the diprotein complex. Now we examine the back reaction and complare the two. We study the effects of temperature (in the range 273.3-302.9 K) and viscosity (in the range 1.00-17.4 cP) on the rate constants and determine enthalpies (DeltaH), entropies (DeltaS), and free energies (DeltaG) of activation. We compare wild-type spinach plastocyanin, the single mutants Tyr83Leu and Glu59Lys, and the double mutant Glu59Lys/Glu60Gln. The rate constant kB for wild-type spinach plastocyanin and its mutants markedly depends on viscosity, an indication that the back reaction is also gated. The activation parameters DeltaH and DeltaS show that the forward and back reactions have similar mechanisms, involving a rearrangement of the diprotein complex from the initial binding configuration to the reactive configuration. The rearrangements of the complexes 3Zncyt/pc(II) and Zncyt+/pc(I) that gate their respective reactions are similar but not identical. Since the back reaction of all plastocyanin variants is faster than the forward reaction, the difference in free energy between the docking and the reactive configuration is smaller for the back reaction than for the forward reaction. This difference is explained by the change in the electrostatic potential on the plastocyanin surface as Cu(II) is reduced to Cu(I). It is the smaller DeltaH that makes DeltaG smaller for the back reaction than for the forward reaction.

Amino Acid Substitution↗
PubMed1999

Improved continuity of care in a community teaching hospital model.

HYPOTHESIS: We created an ambulatory resident clinic in a community teaching hospital to improve the continuity of care in a surgery residency program. DESIGN: A retrospective chart review analysis. SETTING: A community hospital, general surgery residency training program, and its ambulatory practice. INTERVENTIONS: Providence Hospital, Southfield, Mich, has established a new model, the Surgical Associates of Michigan, which is an association comprising private practice physicians serving as full-time faculty in the Department of Surgery. In addition to clarification of teaching requirements and reimbursement for educational activities, the most dramatic feature is the relocation of private practice offices and the staff surgical office to one central location within the hospital. The proximity of the staff and private surgical offices facilitates closer interaction of attending physicians, residents, and patients. MAIN OUTCOME MEASURES: Compliance rates of continuity of patient care provided by the same resident, as presented by the Surgery Residency Review Committee, including confirmation of diagnosis, provision of preoperative care, discussion with attending physician, selection and provision of intervention, direction of postoperative care, and postdischarge follow-up. RESULTS: Since the inception of this arrangement at our institution, surgical residents have seen 229 staff patients and 465 private patients in the offices under supervision. Compliance rate of continuity of care was defined as patient follow-up with the same senior surgical resident who performed an operation or evaluated the patient on initial presentation to the emergency department or offices. We achieved a compliance rate of 92.8% (169/182) in the staff surgical clinics. A compliance rate of 63.5% (205/323) for private general surgical patients and 70.4% (100/142) for vascular surgical patients was obtained. With the establishment of the teaching faculty group and the relocation of offices, we were able to achieve a dramatic improvement in continuity of care. CONCLUSIONS: In addition to fulfilling the Surgery Residency Review Committee requirements, we believe our model facilitates broader education of surgical residents and improves risk management. We recommend further similar studies, greater involvement of primary care specialties in recruiting staff surgical referrals, and implementation of a specialized computer program to continue to improve continuity of care in surgery residency programs.

Continuity of Patient Care↗