AAN conference emphasizes federal measures to curb violence.
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Humans↗
Biomedical subjects
K Smith
Publications and source records attributed to K Smith.
Phenotype of recombinant Leishmania donovani and Trypanosoma cruzi which over-express trypanothione reductase. Sensitivity towards agents that are thought to induce oxidative stress.
Trypanothione reductase is thought to be important in maintaining an intracellular reducing environment in trypanosomatids. To investigate the role of trypanothione reductase we transfected Leishmania donovani and Trypanosoma cruzi with an expression vector containing the L. donovani trypanothione reductase gene and achieved over-expression of enzyme activity (10-14-fold) in transformed cells. Following treatment of L. donovani cells with the thiol-oxidizing agent diamide, the ability to regenerate dihydrotrypanothione from trypanothione disulphide was considerably enhanced in cells which over-expressed trypanothione reductase. However, the growth of transformed and control cells was equally sensitive to inhibition by nifurtimox, nitrofurazone and gentian violet, drugs that are thought to act by inducing oxidative damage. Likewise, growth of transformed and control cells were equally susceptible to inhibition by hydrogen peroxide, and control and transformed L. donovani promastigotes metabolized hydrogen peroxide at comparable rates. Thus, these experiments suggest that the ability to regenerate dihydrotrypanothione from trypanothione disulphide is not a rate-limiting step in the metabolism of hydrogen peroxide.
Animals↗
The glutamyl binding site of trypanothione reductase from Crithidia fasciculata: enzyme kinetic properties of gamma-glutamyl-modified substrate analogues.
Trypanothione reductase, central to the redox defense systems of parasitic trypanosomes and leishmanias, is sufficiently different in its substrate-specificity from mammalian glutathione reductase to represent an attractive target for chemotherapeutic intervention. Previous studies of the physiological substrates trypanothione (N1,N8-bis(glutathionyl)spermidine) and N1-glutathionylspermidine disulphide established that the spermidine moiety of these substrates can be replaced by the 3-dimethyl-propylamide group (N1-glutathionyl-N3-dimethyl-propylamide). With this modification, the specificity for the gamma-glutamyl moiety of the substrate was examined. Kinetic analysis of a series of substrate analogues indicated that neither the alpha-carboxylate or alpha-amino functions of the L-gamma-glutamyl group is essential for recognition, since this group could be replaced by uncharged benzyloxycarbonyl or t-butyloxycarbonyl groups with relative catalytic efficiencies (kcat/Km) of 58 and 11%, respectively, of N1-glutathionyl-N3-dimethylpropylaminedisulphide. Other substitutions are less well tolerated (e.g., beta-L-aspartyl or aminobutyryl) or not at all (e.g., glutaryl). These findings are discussed in relation to the structural model of TR from Trypanosoma congolense. The successful structural replacements achieved have potential application for drug delivery.
Amino Acid Sequence↗
Substrate interactions between trypanothione reductase and N1-glutathionylspermidine disulphide at 0.28-nm resolution.
The enzyme trypanothione reductase has been identified as a prime target for the rational design of inhibitors which may have clinical use in the treatment of tropical diseases caused by the genera Trypanosoma and Leishmania. To aid the design or identification of new inhibitors of this enzyme we have elucidated the structural detail of a trypanothione reductase complexed with one of the naturally occurring substrates, N1-glutathionylspermidine disulphide, by single-crystal X-ray diffraction methods at 0.28-nm resolution. The model for the Crithidia fasciculata enzyme-substrate complex has an R-factor of 14.8% and root-mean-square deviations of 0.0015 nm and 3.3 degrees on bond lengths and angles respectively. Hydrogen bonding and van der Waals interactions between the enzyme and substrate are dominated by the amino acid side chains. The substrate binds in a rigid active site such that one glutathione moiety is in a V-shape, the other in an extended conformation. One spermidine moiety binds closely to a hydrophobic patch in the active site formed by a tryptophan and a methionine. Distances between the methionine S delta and the terminal N of this spermidine suggest that a hydrogen bond may supplement the hydrophobic interactions in this part of the active site.
Animals↗
Natural history of presumed congenital Brown syndrome.
OBJECTIVE: To evaluate the stability of the ocular alignment in patients with presumed congenital Brown syndrome. DESIGN: A retrospective review of patients with Brown syndrome with an emphasis on nonsurgical cases. Follow-up of at least 1 year was required for inclusion in the study. SETTING: Patients were selected for this study from the pediatric ophthalmology services at the Ivey Institute of Ophthalmology, London, Ontario, and the Children's Hospital of Eastern Ontario, Ottawa. PATIENTS: A cohort of 71 patients with presumed congenital Brown syndrome. Two cases were bilateral. Eleven cases were excluded because of insufficient length of follow-up, leaving 60 patients with an average follow-up of 46 months. All patients were assessed and followed up by a pediatric ophthalmologist. RESULTS: Of 38 patients who had no hypotropia in primary position at presentation, only two (5%) patients experienced a worsening with the development of a small vertical strabismus during the follow-up period. Six (10%) of the entire group of 60 patients experienced a complete spontaneous resolution of the deficiency in elevation at 4, 6, 8, 10, 12, and 15 years of age. CONCLUSION: Among patients with congenital Brown syndrome, those who are orthotropic in the primary position tend to remain stable or improve over time without surgical intervention.
Child↗
Comparative trial of clomiphene citrate/human menopausal gonadotropin and the contraceptive pill, followed by clomiphene citrate/human menopausal gonadotropin, in a gamete intrafallopian transfer program.
PURPOSE: It may sometimes be necessary to regulate cycles in assisted reproduction. Cycles can be regulated with gonadotropin releasing hormone (GnRHa) agonist but other methods can also be used. The aim of this study was to compare the pregnancy rate in a gamete intrafallopian transfer (GIFT) program in patients receiving a contraceptive pill/Clomid/human menopausal gonadotropin (hMG) regimen (study group), with the standard Clomid/hMG regime (control group). Fifty one patients in the study group were carefully matched for patient age, infertility diagnosis (female), semen parameters, number of follicles, and number of oocytes transferred into consideration with a control group. RESULTS: The overall pregnancy rate was 21.6% (11/51) in the study group and 47% (24/51) in the control group (P = 0.01). However, the ongoing pregnancy rate in the two groups did not differ significantly, 11.8% (6/51) vs 27.5% (14/51) (P = 0.08). In the study group, 7.8% of patients had to be seen over a weekend, compared to 13.7% in the control group (not significant). CONCLUSION: From the findings we conclude that, although this method of controlling cycles can be useful in selected patients, it is not the ultimate method.
Adult↗
Successful very early in-office treatment of stress test-induced myocardial infarction with anistreplase.
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Ambulatory Care↗
Cathepsin D levels in primary breast cancers: relationship with epidermal growth factor receptor, oestrogen receptor and axillary nodal status.
Cathepsin D and the epidermal growth factor receptor (EGFr) have both been proposed as poor prognostic markers in breast cancer. We have compared the tumour cytosolic cathepsin D level with EGFr and oestrogen receptor (ER) levels and the axillary node status of 131 patients with operable breast cancer, to see if EGFr and cathepsin D are co-regulated. Cathepsin D level was measured using a two-site immunoradiometric assay kit. No correlation was found between the level of cathepsin D and EGFr, ER or nodal status. Since the raised level of cytosolic cathepsin D was not related to EGFr, it may be that measuring the level of both of these markers in the same sample will give additional prognostic information.
Biomarkers, Tumor↗
Increased whole body protein breakdown predominates over increased whole body protein synthesis in multiple organ failure.
1. Whole body protein turnover was measured using a primed-constant infusion of L-[1-13C]leucine with measurement of breath 13CO2 production and plasma 13C alpha-ketoisocaproate enrichment. Ten fasting patients, requiring mechanical ventilation and suffering from multiple organ failure, and six healthy control subjects were studied. 2. Protein breakdown and leucine removal from the plasma for protein synthesis were significantly higher in the patients than in the control subjects (P < 0.01). In addition, leucine oxidation was almost 75% higher in the patients than in the healthy control subjects (P < 0.05). 3. Plasma concentrations of glucose, insulin and growth hormone were not different between the two groups, but those of glucagon (not significant), noradrenaline (P < 0.05) and cortisol (P < 0.01) were almost two- and three-fold higher in the patients than in the control subjects. 4. Mean energy expenditure, measured by indirect calorimetry, was 30% higher in the patients than in the healthy control subjects (P < 0.01). 5. Combining the data from both groups of subjects and using multiple regression analysis, cortisol was found to be the most significant predictor of (i) protein breakdown (48% of variance explained), (ii) leucine oxidation (69%) and (iii) hourly energy expenditure (54%). 6. The present investigation using [13C]leucine tracer methods demonstrated, in patients with multiple organ failure, that whole body protein breakdown and synthesis increased concomitantly and were twice as high as rates measured in healthy control subjects. Of the hormones measured in the present study, cortisol appears to have the most significant effect on whole body protein turnover.
Adult↗
Efficacy of low doses of the polyethylene glycol derivative of interleukin-2 in modulating the immune response of patients with human immunodeficiency virus type 1 infection.
Interleukin-2 (IL-2) is a key cytokine in cellular immunity. Human immunodeficiency virus type 1 (HIV-1)-infected individuals lack IL-2 because of low CD4+ T lymphocyte numbers. In an attempt to enhance cellular immunity, low-dose recombinant human (rh) IL-2 at 10 micrograms or 180,000 units or its polyethylene glycol (PEG) derivative at 9 micrograms or 36,000 units was given by intracutaneous injection to 8 HIV-1-infected men for 30 days. Participants had no evidence of opportunistic infection and received concurrent zidovudine. IL-2 treatment was nontoxic and elicited a local cellular response resembling classic delayed-type hypersensitivity (DTH) with local interferon-gamma production, even in anergic patients. Systemic responses included enhanced DTH responses to recall antigens, improved in vitro proliferative responses to mitogen, and enhanced NK cell activity. Peripheral leukocyte phenotype and virus titers were unchanged. Long-term studies of low-dose IL-2 are warranted to determine whether immunoenhancing effects can be sustained and if they are associated with improved clinical course.
Adult↗
The ability of the hemizona assay to predict human fertilization in different and consecutive in-vitro fertilization cycles.
The objective of this prospective study was to examine the ability of the hemizona assay (HZA) to predict fertilization outcome of mature, pre-ovulatory oocytes under in-vitro fertilization (IVF) conditions. Since a large number of patients were evaluated over a long period, the power of the HZA to prognosticate fertilization results in the same and subsequent (consecutive) IVF cycles of those same patients was assessed. For IVF, only metaphase II oocytes were used. For the HZA, both fresh oocytes donated by patients at the time of IVF and oocytes recovered from surgically removed ovarian tissue (and salt-stored) were used, and bisected by micromanipulation techniques. Matching hemizonae were co-incubated either with spermatozoa from the patient (test) or from a fertile man (control) for 4 h. The number of spermatozoa tightly bound to the zona was counted. Patients (n = 112) were divided into two groups based on HZA results (expressed as HZA index or HZI): HZI > or = 30% (n = 72) and < 30% (n = 40). The patients with HZI < 30% had significantly lower fertilization rates in both the HZA-IVF cycle and in subsequent cycles compared to patients with HZI > or = 30% (P < 0.03). Linear discriminant analysis indicated the HZA to have a sensitivity of 84%, and positive and negative predictive values of 85 and 70% respectively, for prediction of fertilization outcome in a total of 233 cycles. It was concluded that the HZA is a good predictor of fertilization rate in vitro, and can be used in the IVF setting to supply additional clinical information in male-factor patients.
Female↗
Physical and functional characterization of the Bacillus subtilis spoIIM gene.
The spoIIM locus of Bacillus subtilis is the most recently discovered of six genetic loci in which mutations can prevent the synthesis of a normal asymmetric septum or prevent migration of the septal structure to engulf the forespore compartment of the sporangium. Ultrastructure studies of a spoIIM mutant confirmed a block prior to the completion of engulfment. Introduction of a spoIIM mutation into a panel of strains containing lacZ fusions belonging to different regulatory classes allowed us to determine that the spoIIM gene product is required for the efficient expression of genes transcribed by sigma G-associated RNA polymerase but is not required for the expression of sigma F-controlled genes, including spoIIIG, which encodes sigma G. The results of complementation studies, gene disruption analysis, and DNA sequencing revealed that the spoIIM locus contains a single sporulation-essential gene encoding a polypeptide with a predicted molecular mass of 24,850 Da. The predicted spoIIM gene product is highly hydrophobic and very basic, and it does not exhibit significant homology to sequence files in several major data bases.
Amino Acid Sequence↗
Evidence that the spoIIM gene of Bacillus subtilis is transcribed by RNA polymerase associated with sigma E.
We have investigated the temporal and spatial regulation of spoIIM, a gene of Bacillus subtilis whose product is required for complete septum migration and engulfment of the forespore compartment during sporulation. The spoIIM promoter was found to become active about 2 h after the initiation of sporulation. The effects of mutations on the expression of a spoIIM-lacZ fusion were most consistent with its utilization by sigma-E-associated RNA polymerase (E sigma E). A unique 5' end of the in vivo spoIIM transcript was detected by primer extension analysis and was determined to initiate at the appropriate distance from a sequence conforming very closely to the consensus for genes transcribed by E sigma E. A partially purified preparation of E sigma E produced a transcript in vitro that initiated at the same nucleotide as the primer extension product generated from in vivo RNA. Ectopic induction of sigma E synthesis during growth resulted in the immediate and strong expression of a spoIIM-lacZ fusion, but an identical fusion was completely unresponsive to induced synthesis of either sigma F or sigma G under similar conditions. The results of plasmid integration-excision experiments in which the spoIIM gene was reversibly disrupted by a temperature-sensitive integrational vector suggested that spoIIM expression is required in the forespore compartment, but direct examination of subcellular fractions enriched for mother cell or forespore material indicated that spoIIM expression cannot be confined to the forespore. We conclude that spoIIM is a member of the sigma E regulon and that it may be transcribed exclusively by E sigma E. We discuss the implications of this conclusion for models in which activation of sigma E in the mother cell is proposed to be a part of the mechanism responsible for initiating separate programs of gene activity in the two sporangium compartments.
Bacillus subtilis↗
Retrospective study of prognostic value of DNA ploidy and proliferative activity in neuroblastoma.
AIM: To assess the prognostic value of age and stage at diagnosis, site of primary tumour, cell ploidy and N-myc copy number in children with neuroblastoma. METHODS: Flow cytometry was used to determine the cellular DNA content of paraffin wax embedded archival material from 69 cases of neuroblastoma and was successful in 52. RESULTS: The age, stage, and survival distribution of the sampled cases was not significantly different from that in a larger population based series. There were seven diploid ("non-aneuploid") and 45 aneuploid (including two tetraploid and four triploid) tumours. The 10 year survival was significantly better for cases of aneuploid rather than diploid tumours (p < 0.05). An important new finding was that 10 year survival was also significantly better for tumours with a low percentage of cells in S phase (p < 0.03). CONCLUSION: The percentage of cells in S phase, a measure of the proliferative activity of the tumour, correlated with prognosis in neuroblastoma. This should be measured with other biological features of the disease, such as N-myc copy number, when prognostic indicators are being assessed.
Adolescent↗
Protein turnover in the human fetus studied at term using stable isotope tracer amino acids.
Before elective cesarean delivery (4 h), we infused L-[1-13C]leucine and L-[15N]phenylalanine into the maternal circulation and measured enrichment and concentration of amino acids and carbon dioxide in cord blood of six normal human fetuses at delivery. There were net fetal uptakes of leucine (2.22 +/- 0.29 mumol.kg-1.min-1) and phenylalanine (0.80 +/- 0.11 mumol.kg-1.min-1) with net outputs of CO2 (6.11 +/- 1.12 ml.kg-1.min-1) and the transamination product of leucine, alpha-ketoisocaproate (1.04 +/- 0.32 mumol.kg-1.min-1). Fetal amino acid oxidation accounted for a substantial proportion of the flux from the mother (leucine, 0.36 +/- 0.09 mumol.kg-1.min-1 and phenylalanine, 0.18 +/- 0.04 mumol.kg-1.min-1). Fetal whole body accretion of leucine carbon (0.82 +/- 0.21 mumol.kg-1.min-1) was 69% of the umbilical uptake, and that of phenylalanine (0.62 +/- 0.08 mumol.kg-1.min-1) was 78%. Fetal whole body protein synthesis was approximately 13 g.kg-1.day-1, i.e., much faster than in adults but similar to that in the newborn. Net protein accretion was 2-4 g.kg-1.day-1. The placental supply of leucine and phenylalanine exceeds the fetal demand for protein synthesis by only a small amount, suggesting that the safety margin of placental transfer may be small for these amino acids. The results suggest that the method could be applied safely to studies of fetal growth retardation.
Adult↗
Acute renal failure associated with intramuscular ketorolac.
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Acute Kidney Injury↗
Improving diabetes care for American Indians.
In 1986, a diabetes control program was implemented in the Billings area of the IHS. Baseline health-care practices in the program were described using a structured audit. The program included adoption of the IHS Minimum Standards of Care for diabetes, technical assistance, and professional and patient education. A second audit was performed in 1988. Care practices improved significantly for all facilities in 7 of 10 parameters measured. Facilities that implemented key program activities showed more overall improvement in screening practices, education, and immunization than those that did not organize diabetes care. Factors associated with improved care practices include establishment of a coordinated, multidisciplinary diabetes team with regular meetings, acceptance of standards of care by the medical staff, use of flow sheets by multiple providers, and diabetes-related professional and patient education sessions.
Diabetes Mellitus↗
Topoisomerase II alpha co-amplification with erbB2 in human primary breast cancer and breast cancer cell lines: relationship to m-AMSA and mitoxantrone sensitivity.
Topoisomerase II alpha (topo II alpha) is a key enzyme in DNA replication and a target for many anti-cancer drugs. High levels are associated with sensitivity to topoisomerase II inhibitors. Because its chromosome location is similar to erbB2 (17q21-22), which is frequently amplified in breast cancer, co-amplification of these genes was assessed. In 117 primary breast cancers, 25 were amplified for erbB2. Three of these cases showed co-amplification of topo II alpha. Topo II beta was not amplified. Four human breast cancer cell lines were assessed for erbB2 and topo II alpha co-amplification. They were also analysed for sensitivity to the topoisomerase inhibitors m-AMSA and mitoxantrone. The most sensitive cell line was SKBr3, which was the only one with erbB2 amplification. Topo II alpha was co-amplified to a similar extent as in tumours. This suggests that patients whose tumours show topo II alpha amplification should be assessed specifically for therapy with topoisomerase inhibitors.
Adult↗