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Biomedical subjects

C Smith

Publications and source records attributed to C Smith.

At least 55 records · Page 3Linked to original sources

Emergency department admissions to inpatient cardiac telemetry beds: a prospective cohort study of risk stratification and outcomes.

PURPOSE: Little is known about physicians' use of inpatient cardiac telemetry units among emergency department patients at risk for cardiac complications. We therefore studied the outcomes of patients admitted to inpatient telemetry beds to identify a subset of patients from whom cardiac monitoring could be withheld safely. SUBJECTS AND METHODS: We conducted a prospective cohort study of 1, 033 consecutive adult patients admitted to an inpatient telemetry unit from the emergency department of a 700-bed urban public teaching hospital. Subjects with or without chest pain were risk-stratified using a prediction rule and observed for in-hospital cardiac complications, acute myocardial infarction, and transfer to an intensive care unit (ICU). RESULTS: There were no significant differences between patients with (n = 677) or patients without chest pain (n = 356) in the rates of major cardiac complications, myocardial infarctions, or transfers to an ICU. Among 318 patients with chest pain who were classified as being very low risk, none suffered major complications (negative predictive value 100%; 95% confidence interval [CI]: 98.8% to 100%). Among 214 very low risk patients without chest pain, 1 (0.5%) had a major complication (negative predictive value 99.5%; 95% CI: 97.4% to 99.9%). CONCLUSIONS: The prediction rule accurately identified patients with or without chest pain who were at very low risk of major complications, identifying a subset from whom cardiac monitoring could be withheld safely.

Adolescent↗

An extracorporeal membrane oxygenation-based approach to cardiogenic shock in an older population.

BACKGROUND: We investigated the efficacy of an integrated system of advanced supportive care based on extracorporeal membrane oxygenation (ECMO) in older patients with an estimated mortality of more than 90% to establish whether its use is justifiable. METHODS: Treatment was provided by cardiac surgeons and critical care physicians and included the following key elements: (1) ECMO, (2) early application of continuous venovenous hemofiltration, (3) inhaled nitric oxide, (4) maintenance of perfusion pressure with norepinephrine, (5) maintenance of pulmonary blood flow by ventricular filling with intravenous colloids, (6) avoidance of early postoperative anticoagulation, (7) frequent use of transesophageal echocardiography, and (8) low tidal volume ventilation. Demographic features, intraoperative details, postoperative course, ECMO weaning rate, morbidity, survival to hospital discharge, and the quality of life of survivors were recorded. RESULTS: Seventeen consecutive patients (median age, 69 years) with refractory cardiogenic shock were studied. The median duration of ECMO was 86 hours (20 to 201 hours). Eleven patients (65%) were successfully weaned from ECMO. Seven patients (41%) survived to discharge. The major causes of morbidity were bleeding and leg ischemia. All patients who survived to discharge were alive and well at follow-up (median, 21 months) and reported a satisfactory quality of life. CONCLUSIONS: An ECMO-based approach can be used with acceptable results in the treatment of refractory cardiogenic shock, even in older patients.

Aged↗

Concurrent weekly carboplatin and radiotherapy for nasopharyngeal carcinoma: report of a joint phase II study.

We report a phase I/II study of weekly concurrent carboplatin and radiotherapy in patients with nasopharyngeal carcinoma (M0 stage). Of 47 patients registered, 45 completed the treatment course. Twenty-six (55%) (95% CI, 41-69%) patients experienced > or =grade 3 acute toxicity (RTOG). Five (11%) (95% CI, 2-20%) patients experienced > or =grade 3 chronic toxicity. This regimen appears to have acceptable toxicity compared to the experimental arm of Phase III Intergroup Study 0099, but progression-free and overall survival are probably inferior. At present, there is no data to suggest that carboplatin can replace cisplatin for concurrent chemoradiation for NPC.

Adult↗

Sustained elevation of calcium induces Ca(2+)/calmodulin-dependent protein kinase II clusters in hippocampal neurons.

Treatment of cultured hippocampal neurons with the mitochondrial uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP) in the absence of glucose mimics ischemic energy depletion and induces formation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) clusters, spherical structures with diameters of 75-175 nm [Dosemeci et al., J. Neurosci. 20 (2000) 3076-3084]. The demonstration that CaMKII clustering occurs in the intact, adult rat brain upon interruption of blood flow indicates that clustering is not confined to cell cultures. Application of N-methyl-D-aspartate (250 microM, 15 min) to hippocampal cultures also induces cluster formation, suggesting a role for Ca(2+). Indeed, intracellular Ca(2+) monitored with Fluo3-AM by confocal microscopy reaches a sustained high level within 5 min of CCCP treatment. The appearance of immunolabeled CaMKII clusters, detected by electron microscopy, follows the onset of the sustained increase in intracellular Ca(2+). Moreover, CaMKII does not cluster when the rise in intracellular Ca(2+) is prevented by the omission of extracellular Ca(2+) during CCCP treatment, confirming that clustering is Ca(2+)-dependent. A lag period of 1-2 min between the onset of high intracellular Ca(2+) levels and the formation of CaMKII clusters suggests that a sustained increase in Ca(2+) level is necessary for the clustering. CaMKII clusters disappear within 2 h of returning the cultures to normal incubation conditions, at which time no significant cell death is detected. These results indicate that pathological conditions that promote sustained episodes of Ca(2+) overload result in a transitory clustering of CaMKII into spherical structures. CaMKII clustering may represent a cellular defense mechanism to sequester a portion of the CaMKII pool, thereby preventing excessive protein phosphorylation.

Age Factors↗

Experience-dependent changes in cerebral functional connectivity during human rapid eye movement sleep.

One function of sleep is hypothesized to be the reprocessing and consolidation of memory traces (Smith, 1995; Gais et al., 2000; McGaugh, 2000; Stickgold et al., 2000). At the cellular level, neuronal reactivations during post-training sleep in animals have been observed in hippocampal (Wilson and McNaughton, 1994) and cortical (Amzica et al., 1997) neuronal populations. At the systems level, using positron emission tomography, we have recently shown that some brain areas reactivated during rapid-eye-movement sleep in human subjects previously trained on an implicit learning task (a serial reaction time task) (Maquet et al., 2000). These cortical reactivations, located in the left premotor area and bilateral cuneus, were thought to reflect the reprocessing--possibly the consolidation--of memory traces during post-training rapid-eye-movement sleep. Here, the experience-dependent functional connectivity of these brain regions is examined. It is shown that the left premotor cortex is functionally more correlated with the left posterior parietal cortex and bilateral pre-supplementary motor area during rapid-eye-movement sleep of subjects previously trained to the reaction time task compared to rapid-eye-movement sleep of untrained subjects. The increase in functional connectivity during post-training rapid-eye-movement sleep suggests that the brain areas reactivated during post-training rapid-eye-movement sleep participate in the optimization of the network that subtends subject's visuo-motor response. The optimization of this visuo-motor network during sleep could explain the gain in performance observed during the following day.

Brain Mapping↗

Care of the dying: setting standards for symptom control in the last 48 hours of life.

The hospice model of care of the dying patient is regarded as a model of excellence; however, outcomes of this care have been poorly demonstrated. Integrated Care Pathways (ICPs) provide a method of recording and measuring outcomes of care. The ICP document replaces all previous documentation and is a multiprofessional record of patient care. The aim of this study was to implement an ICP in an inpatient hospice setting in order to set standards of care for symptom control in the dying phase of a patient's life. ICPs were analyzed from 168 inpatients who died over a one-year period. Symptoms of pain, agitation, and respiratory tract secretions (RTS) were monitored every four hours by nursing staff as either present or absent. For each symptom, 80% of patients had one episode or complete control of the symptom, 10% had two episodes, and 10% had three episodes or more recorded. As death neared, there was a statistically significant increase in the number of patients whose pain was controlled. The ICP has provided a means to measure symptom control in the dying patient and set standards of care, which is integrated into clinical practice.

Adult↗

Predictors of general surgical complications after heart transplantation.

BACKGROUND: Several studies have reported the incidence, morbidity, and mortality of general surgical conditions (GSCs) in orthotopic heart transplant (OHT) patients. The following is the largest reported series of such patients and the first study with sufficient patient numbers to formally evaluate peritransplant variables as risk factors for GSC development. STUDY DESIGN: A GSC was defined as a condition for which a general surgeon had been consulted or as a general surgical condition recognized at the time of autopsy. The records of 453 consecutive patients who underwent OHT between 1981 and 1999 were reviewed to identify patients who developed a GSC. Kaplan-Meier actuarial analysis on this cohort, and univariate and multivariate logistic regression models applied to a subpopulation of 324 consecutive OHT patients between 1987 and 1997 were used to determine factors associated with and predictive of GSC after OHT. RESULTS: Of 453 OHT patients, 371 (81.9%) were men, and the average age was 44.5 +/- 15 (standard deviation) years. Median followup was 2,086 days (range 1 to 6,642 days). Ninety-three patients (20.5%) developed 111 GSCs. Of these, 78 were men, and the average age was 49.9+/-10.2 years. There were 83 general surgical interventions. Actuarial analyses revealed that age greater than 50 years, pretransplant diagnosis of ischemic (PTDxI) versus nonischemic heart disease, and previous general surgical history were factors associated (p < 0.05) with a higher GSC incidence. Gender, more urgent transplant priority status, cardiopulmonary bypass time, total graft ischemic time, and intensive care unit length of stay were not associated with GSC. Factors associated with GSC on univariate analysis, with odds ratios (ORs) and 95% confidence intervals (CIs) included: age analyzed as a continuous variable (OR 1.04 per year; CI 1.01, 1.06 per year; p = 0.0021), PTDxI (OR 2.40; CI 1.39, 4.15; p = 0.0016), and pretransplant general surgical history (OR 3.35; CI 1.65, 6.82; p = 0.0008). Multivariate analysis revealed that only pretransplant general surgical history (OR 3.27; CI 1.58, 6.76; p = 0.0004) and PTDxI (OR 2.37; CI 1.35, 4.16; p = 0.0023) were associated with subsequent development of GSC. CONCLUSIONS: A pretransplant diagnosis of ischemic heart disease and previous history of a general surgical procedure are two independent risk factors that predispose OHT patients to development of GSC. Because GSC may arise insidiously in immunosuppressed patients, identification of OHT patients at higher risk for GSC will permit timely intervention decisions, decreasing morbidity and mortality in this challenging group of patients.

Adult↗

Myc requires distinct E2F activities to induce S phase and apoptosis.

Previous work has shown that the Myc transcription factor induces transcription of the E2F1, E2F2, and E2F3 genes. Using primary mouse embryo fibroblasts deleted for individual E2F genes, we now show that Myc-induced S phase and apoptosis requires distinct E2F activities. The ability of Myc to induce S phase is impaired in the absence of either E2F2 or E2F3 but not E2F1 or E2F4. In contrast, the ability of Myc to induce apoptosis is markedly reduced in cells deleted for E2F1 but not E2F2 or E2F3. From this data, we propose that the induction of specific E2F activities is an essential component in the Myc pathways that control cell proliferation and cell fate decisions.

Adenoviridae↗

Effect of glycation on basic fibroblast growth factor induced angiogenesis and activation of associated signal transduction pathways in vascular endothelial cells: possible relevance to wound healing in diabetes.

Ineffectual wound healing in hyperglycaemic patients suffering from diabetes mellitus is characterised by a reduction in capillary reformation (angiogenesis). Basic fibroblast growth factor (FGF-2) is secreted by fibroblasts, macrophages and in particular endothelial cells (EC) in response to tissue injury and is important in promotion of neovascularisation. Recently, glycation of FGF-2 has been shown to significantly reduce its activity in vitro. We have examined the kinetics of FGF-2 glycation and compared its ability with that of native FGF-2 to activate mitogenesis, capillary formation and associated signal transduction in bovine aortic EC (BAEC). FGF-2 was exposed to 0.25 M glucose-6-phosphate (G-6-P) for 24-72 h and the degree of glycation determined by matrix assisted laser desorption ionisation mass spectrometry. Native FGF-2 was heterogeneous with Mw in the range 15,153.6-17,903 Da. After 24 h incubation with G-6-P there was evidence of glycation, and the mass increase corresponded to addition of 2.7 mol of G-6-P residues; after 48 h, 4 mol sugar was added and this increased to 8.7 after 72 h. Dimerisation of FGF-2 was observed after 72 h of treatment. Induction of mitogenesis in BAEC was significantly reduced by 25%-40% after treatment for 48-96 h with glycated (24 h) FGF-2 (gFGF-2; 100 pg/ml-5 ng/ml; P < 0.05), whilst capillary tubule formation was significantly reduced by between 60% and 90% (100 pg/ml-1 ng/ml; P < 0.05) after 5 days compared to native FGF-2. Subsequent investigation of the signal transduction molecules associated with mitogenesis showed a reduction in FGF-2 induced tyrosine phosphorylated proteins of approximate Mw 20-150 kDa between 10 min and 24 h, in particular, mitogen activated protein kinase (MAPK)/early response kinase (ERK-1, ERK-2), after glycation. To determine the reason for reduced angiogenic activity of gFGF-2, we compared its binding characteristics to that of native FGF-2. Total binding of gFGF-2 to the cell surface was significantly reduced in BAEC analysed by FACS compared to native FGF-2 (P < 0.05). Further investigation using 125I-labelled differentially washed samples, demonstrated a significant reduction in gFGF-2 binding to the high affinity tyrosine kinase receptor (46%) compared to native FGF-2. In summary, glycation of FGF-2 in vitro occurs rapidly within 24 h in the presence of elevated levels of G-6-P. Glycation caused a significant reduction in the ability of FGF-2 to bind to the tyrosine kinase receptor and activate signal transduction pathways responsible for both mitogenesis and capillary formation in BAEC. These results could help to explain the mechanism behind impaired wound healing in patients with diabetes mellitus.

Animals↗

Efficacy of manual and powered toothbrushes (II). Effect on microbiological parameters.

BACKGROUND/AIM: The purpose of the present investigation was to determine the effect of self-performed supragingival plaque removal using either manual (Crest Complete) or power (Braun 3D Plaque Remover) toothbrushing on supra and subgingival plaque composition. METHODS: 47 periodontal maintenance subjects completed this single-blind 6 month longitudinal study. At baseline, samples of supra and separately subgingival plaque were taken from the mesial aspect of each tooth in each subject using sterile curettes and individually analyzed for their content of 18 bacterial taxa using checkerboard DNA-DNA hybridization. After random assignment to groups receiving either a manual (n=25) or power toothbrush (n=22), subjects received instruction in oral hygiene and used their assigned toothbrush 2x daily for 6 months. Clinical monitoring and microbiological sampling were repeated at 3 and 6 months. Significant differences in microbiological measures over time were sought using the Quade test and between brushing groups at each time point using the Mann-Whitney test. RESULTS: Mean total counts were significantly reduced for supra- and subgingival plaque samples in the manual group and subgingival samples in the powered brushing group. Actinomyces naeslundii and Actinomyces israelii/gerencseriae were the most numerous organisms detected at baseline and showed the greatest reductions in counts in both brushing groups. Streptococcus constellatus/intermedius was significantly reduced in both groups, while Streptococcus mitis/oralis/sanguis was significantly reduced in the manual toothbrushing group. Mean counts of species were more markedly altered in subgingival plaque. Major reductions occurred in both groups for A. naeslundii, A. israelii/gerencseriae, Peptostreptococcus micros, Veillonella parvula, Prevotella intermedia/nigrescens, S. mitis/oralis/sanguis and S. constellatus/intermedius. All taxa examined were reduced in prevalence (% of sites colonized) in the subgingival plaque samples for both brushing groups. The reductions in prevalence were greater for A. naeslundii, S. constellatus/intermedius, V. parvula, A. israelii/gerencseriae, S. mitis/oralis/sanguis, P. micros, Streptococcus mutans and P. intermedia/nigrescens. Mean prevalence was decreased more for Porphyromonas gingivalis, Campylobacter rectus/showae, Treponema denticola and Bacteroides forsythus in supragingival plaque than subgingival plaque. CONCLUSIONS: The major finding was the effect of supragingival plaque removal on the composition of the subgingival microbiota. Counts and prevalence of most taxa examined were markedly decreased in both toothbrushing groups. This reduction should translate to a decreased risk of periodontal disease initiation or recurrence. Further, the decreased prevalence of periodontal pathogens in supragingival plaque lowers potential reservoirs of these species.

Actinomyces↗

Congenital thyrotoxicosis in premature infants.

OBJECTIVES: Graves' disease (GD) complicates 0.1% to 0.2% of pregnancies, but congenital thyrotoxicosis is rare occurring in one in 70 of these pregnancies independent of maternal disease status. Antenatal prediction of affected infants is imprecise; however, maternal history, coupled with a high maternal serum TSH receptor binding immunoglobulin index (TBII) predict adverse neonatal outcome. Mortality is reported to be as high as 25% in affected infants and would therefore be expected to be higher in premature infants. This study illustrates that in sick, premature, extreme low birth weight (ELBW) or intrauterine growth retarded (IUGR) infants, the diagnosis maybe overlooked especially in the absence of antenatal risk assessment and management of thyrotoxicosis in this setting is complex. DESIGN AND PATIENTS: The records of premature neonates born at the three main maternity units in Brisbane, between January 1996 and July 1998 diagnosed with congenital thyrotoxicosis were reviewed. Data were recorded on gestational age, birth weight (B Wt), maternal thyroid history and current status, and neonatal course. Thyroid function and TBII status was assessed using standard biochemical assays. RESULTS: Seven neonates from five pregnancies were identified (four female, three male). Mean gestational age was 30 week (25--36 week) and median B Wt was 1.96 kg (0.50--2.62 kg). Only one mother received formal antenatal counselling by a paediatric endocrine service and had a TBII (54%) measured prior to delivery. Three of five mothers had elevated TBII measured after diagnosis in their offspring (57%, 65%, 83%) and in one mother, a TBII was not performed. All mothers were biochemically euthyroid at delivery. Mean age at diagnosis was 9 days (1--16 days) and mean age at commencement of treatment was 12 days (7--26 days). Two infants received propylthiouracil and five received a combination of carbimazole and propranolol. Four became biochemically hypothyroid, in three this resolved with cessation of the antithyroid drug (ATD), and one required ongoing T4 supple-mentation. Only one infant required treatment for cardiac failure and there were no deaths in this cohort. CONCLUSIONS: This is a large series of extremely small and premature infants with neonatal thyro-toxicosis. Presentation was nonspecific. The diagnosis was delayed because of low birth weight, prematurity, multiple birth and/or an unrecognized maternal history of Graves' disease. The treatment of neonatal thyrotoxicosis was difficult in these extreme low birth weight infants yet no infant died and significant morbidity was confined to high output cardiac failure in one infant. With antenatal recognition of past or active Graves' disease, assessment of maternal TSH receptor binding immunoglobulin index prior to delivery and postnatal monitoring of cord TSH and venous fT4 and TSH on days 4 and 7 rapid treatment of affected infants may have further reduced neonatal morbidity.

Antithyroid Agents↗

Impaired sucrose-induction mutants reveal the modulation of sugar-induced starch biosynthetic gene expression by abscisic acid signalling.

Plants both produce and utilize carbohydrates and have developed mechanisms to regulate their sugar status and co-ordinate carbohydrate partitioning. High sugar levels result in a feedback inhibition of photosynthesis and an induction of storage processes. We used a genetic approach to isolate components of the signalling pathway regulating the induction of starch biosynthesis. The regulatory sequences of the sugar inducible ADP-glucose pyrophosphorylase subunit ApL3 were fused to a negative selection marker. Of the four impaired sucrose induction (isi) mutants described here, two (isi1 and isi2) were specific to this screen. The other two mutants (isi3 and isi4) showed additional phenotypes associated with sugar-sensing screens that select for seedling establishment on high-sugar media. The isi3 and isi4 mutants were found to be involved in the abscisic acid signalling pathway. isi3 is allelic to abscisic acid insensitive4 (abi4), a gene encoding an Apetala2-type transcription factor; isi4 was found to be allelic to glucose insensitive1 (gin1) previously reported to reveal cross-talk between ethylene and glucose signalling. Here we present an alternative interpretation of gin1 as an allele of the ABA-deficient mutant aba2. Expression analysis showed that ABA is unable to induce ApL3 gene expression by itself, but greatly enhances ApL3 induction by sugar. Our data suggest a major role for ABA in relation to sugar-signalling pathways, in that it enhances the ability of tissues to respond to subsequent sugar signals.

Abscisic Acid↗

Consumers' views of quality in the consultation and their relevance to 'shared decision-making' approaches.

BACKGROUND: There is a recognized need to assess the effects of shared decision-making and other communication interventions. However, the outcomes usually assessed for evidence of 'effectiveness' are determined by researchers and have not been based on consumers' views. AIM: This study aimed to identify the important outcomes of consultations for consumers, and to compare with those reported in the current literature. SETTING AND PARTICIPANTS: Forty-seven participants attending six focus group interviews. Most interviews took place in and all were orientated towards the UK primary care setting. METHODS: Focus group study. RESULTS: Many affective outcomes were identified, consistent with the current literature trends. However, many cognitive and behavioural outcomes that are assessed in the current literature were not noted by participants as important. Furthermore, a broader range of outcomes than is evident in the current literature was viewed as important to these participants. CONCLUSIONS: There is a need to revisit the outcomes which are assessed in decision-making and communication research. The outcomes of greatest importance to consumers must be identified and confirmed by new research which is based directly on the views of consumers themselves.

Consumer Behavior↗

Differential expression of fibroblast growth factor-2 and fibroblast growth factor receptor 1 in a scarring and nonscarring model of CNS injury in the rat.

Injury to the adult brain results in abortive axon regeneration and the deposition of a dense fibrous glial scar. Therapeutic strategies to promote postinjury axon regeneration are likely to require antiscarring strategies. In neonatal brain wounds, scar material is not laid down and axons grow across the lesion site, either by de novo growth or regeneration. To achieve the therapeutic goal of recapitulating the nonscarring neonatal response in the injured adult, an understanding of how ontogenic differences in scarring reflect developmental diversities in the trophic response to injury is required. Fibrobast growth factor-2 (FGF-2) expression is developmentally regulated and has been implicated as a regulator of the wounding response of the adult rat central nervous system. We have investigated the expression of FGF-2 and fibroblast growth factor receptor 1 (FGFR1) after penetrating lesions to the cerebral cortex of 5 days post partum (dpp) (nonscarring) and 16 dpp and adult (scarring) rats. In situ hybridization, immunohistochemistry and Western blotting showed robust and sustained increases in FGF-2 and FGFR1 mRNA and protein in reactive astrocytes around the lesion in scarring rats, a response that was attenuated substantially in the nonscarring neonate. These results demonstrate that changes in astrocyte FGF-2 and FGFR1 expression are coincident with the establishment of a mature pattern of glial scarring after injury in the maturing central nervous system, but it is premature to infer a causal relationship without further experiments.

Age Factors↗

Efficacy and safety of pegylated (40-kd) interferon alpha-2a compared with interferon alpha-2a in noncirrhotic patients with chronic hepatitis C.

Administration of interferon (IFN) 3 times weekly in patients with chronic hepatitis C (CHC) is associated with low sustained responses, which may be, in part, related to this regimen's inability to maintain IFN concentrations sufficient to suppress viral replication. An enhanced IFN molecule produced by the covalent attachment of a branched 40-kd polyethylene glycol moiety to IFN alpha-2a (PEG[40kd] IFN alpha-2a) exhibits sustained absorption, a restricted volume of distribution, and reduced clearance compared with unmodified IFN alpha-2a. One hundred fifty-nine patients with CHC participated in a randomized, ascending-dose (45 or 90, 180, 270 microg) study comparing PEG(40kd) IFN alpha-2a administered once weekly with 3 MIU IFN alpha-2a administered 3 times weekly for 48 weeks to determine the most appropriate PEG(40kd) IFN alpha-2a dose for subsequent clinical trials. Efficacy was assessed by measuring hepatitis C virus (HCV) RNA following a 24-week treatment-free period. Sustained virological responses for PEG(40kd) IFN alpha-2a once weekly were 10% (45 microg; not significant), 30% (90 microg; P = .009), 36% (180 microg; P = .0006), and 29% (270 microg; P = .004), compared with 3% for the 3-times-weekly 3-MIU IFN alpha-2a regimen. The types and frequencies of adverse events and laboratory abnormalities were similar among all groups. In conclusion, once-weekly PEG(40kd) IFN alpha-2a was associated with a higher number of sustained virological responses compared with IFN alpha-2a 3 times weekly in patients with CHC, but had a similar safety profile. The 180-microg PEG(40kd) IFN alpha-2a dose appeared to be the optimal dose based on sustained virological response and its associated side-effect profile.

Adult↗