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Biomedical subjects

Stephen Davis

Publications and source records attributed to Stephen Davis.

At least 19 recordsLinked to original sources
PubMed2006

Anxiety in speakers who persist and recover from stuttering.

PURPOSE: The study was designed to see whether young children and adolescents who persist in their stutter (N=18) show differences in trait and/or state anxiety compared with people who recover from their stutter (N=17) and fluent control speakers (N=19). METHOD: A fluent control group, a group of speakers who have been documented as stuttering in the past but do not stutter now and a group of speakers (also with a documented history of stuttering) who persist in their stuttering participated, all aged 10-17 years. The State-Trait Anxiety Inventory for Children was administered. RESULTS: There were no differences between persistent, recovered and control groups with regard to trait anxiety. The persistent group had higher state anxiety than controls and the recovered group for three out of four speaking situations. CONCLUSION: The findings are interpreted as showing that anxiety levels in certain affective states appear to be associated with the speaking problem. LEARNING OUTCOMES: A reader should be able to appreciate the difference between state and trait anxiety understand views about how the role anxiety has on stuttering has changed over time appreciate different views about how anxiety affects speakers who persist and recover from stuttering see why longitudinal work is needed to study these issues.

Adaptation, Psychological↗
PubMed2006

Economic evaluation of Australian stroke services: a prospective, multicenter study comparing dedicated stroke units with other care modalities.

BACKGROUND AND PURPOSE: Level I evidence from randomized controlled trials demonstrates that the model of hospital care influences stroke outcomes; however, the economic evaluation of such is limited. An economic appraisal of 3 acute stroke care models was facilitated through the Stroke Care Outcomes: Providing Effective Services (SCOPES) study in Melbourne, Australia. The aim was to describe resource use up to 28 weeks poststroke for each model and examine the cost-effectiveness of stroke care units (SCUs). METHODS: A prospective, multicenter, cohort study design was used. Costs and outcomes of stroke patients receiving 100% treatment in 1 of 3 inpatient care models (SCUs, mobile service, conventional care) were compared. Health-sector resource use up to 28 weeks was measured in 1999. Outcomes were thorough adherence to a suite of important clinical processes and the number of severe inpatient complications. RESULTS: The sample comprised 395 participants (mean age 73 [SD 14], 77% first-ever strokes, males 53%). When compared with conventional care (n=84), costs for mobile service (n=209) were significantly higher (P=0.024), but borderline for SCU (n=102, P=0.08; 12,251 Australian dollars; 15,903 Australian dollars; 15,383 Australian dollars respectively). This was primarily explained by the greater use of specialist medical services. The incremental cost-effectiveness of SCUs over conventional care was 9867 Australian dollars per patient achieving thorough adherence to clinical processes and 16,372 Australian dollars per patient with severe complications avoided, based on costs to 28 weeks. CONCLUSIONS: Although acute SCU costs are generally higher, they are more cost-effective than either mobile service or conventional care.

Aged↗
PubMed2006

Auditory abilities of speakers who persisted, or recovered, from stuttering.

OBJECTIVE: The purpose of this study was to see whether participants who persist in their stutter have poorer sensitivity in a backward masking task compared to those participants who recover from their stutter. DESIGN: The auditory sensitivity of 30 children who stutter was tested on absolute threshold, simultaneous masking, backward masking with a broadband and with a notched noise masker. The participants had been seen and diagnosed as stuttering at least 1 year before their 12th birthday. The participants were assessed again at age 12 plus to establish whether their stutter had persisted or recovered. Persistence or recovery was based on participant's, parent's and researcher's assessment and Riley's [Riley, G. D. (1994). Stuttering severity instrument for children and adults (3rd ed.). Austin, TX: Pro-Ed.] Stuttering Severity Instrument-3. Based on this assessment, 12 speakers had persisted and 18 had recovered from stuttering. RESULTS: Thresholds differed significantly between persistent and recovered groups for the broadband backward-masked stimulus (thresholds being higher for the persistent group). CONCLUSIONS: Backward masking performance at teenage is one factor that distinguishes speakers who persist in their stutter from those who recover. Education objectives: Readers of this article should: (1) explain why auditory factors have been implicated in stuttering; (2) summarise the work that has examined whether peripheral, and/or central, hearing are problems in stuttering; (3) explain how the hearing ability of persistent and recovered stutterers may differ; (4) discuss how hearing disorders have been implicated in other language disorders.

Adolescent↗
PubMed2006

Plague dynamics are driven by climate variation.

The bacterium Yersinia pestis causes bubonic plague. In Central Asia, where human plague is still reported regularly, the bacterium is common in natural populations of great gerbils. By using field data from 1949-1995 and previously undescribed statistical techniques, we show that Y. pestis prevalence in gerbils increases with warmer springs and wetter summers: A 1 degrees C increase in spring is predicted to lead to a >50% increase in prevalence. Climatic conditions favoring plague apparently existed in this region at the onset of the Black Death as well as when the most recent plague pandemic arose in the same region, and they are expected to continue or become more favorable as a result of climate change. Threats of outbreaks may thus be increasing where humans live in close contact with rodents and fleas (or other wildlife) harboring endemic plague.

Animals↗
PubMed2006

Lower target blood pressures are safe and effective for the prevention of recurrent stroke: the PROGRESS trial.

OBJECTIVE: To explore the likely optimum blood pressure (BP) level for patients with a history of cerebrovascular disease. METHODS: The Perindopril Protection Against Recurrent Stroke Study (PROGRESS) was a randomized, placebo-controlled trial that established the beneficial effects of BP lowering in 6105 patients with cerebrovascular disease. The present study comprises two series of post hoc analyses. The first was designed to investigate the effects of randomized treatment on recurrent stroke by baseline BP levels, and the second was a corresponding observational analysis investigating the association between achieved follow-up BP levels and recurrent stroke risk. RESULTS: Analyses of the randomized treatment comparisons showed that BP lowering with combination therapy produced similar risk reductions in each of four subgroups defined by baseline BP of less than 120, 120-139, 140-159, and 160 mmHg or greater (P homogeneity = 0.5). The effects of single-drug therapy were also comparable across these subgroups (P homogeneity = 0.2), but consistently greater benefits were observed with combination compared to single-drug therapy. The analyses of achieved follow-up BP showed that the lowest risk of recurrence was among the one-quarter of participants with the lowest follow-up BP levels (median 112/72 mmHg), and that risks rose progressively with higher follow-up BP levels. Minor side-effects were progressively more common at lower BP levels (P homogeneity = 0.04), but there was no excess of serious complications (all P homogeneity > 0.2). CONCLUSION: These analyses provide no evidence of a J-curve relationship between BP level and stroke risk among patients with cerebrovascular disease, and identify no patient group among whom more intensive BP lowering would not be expected to produce greater risk reductions.

Aged↗
PubMed2006

Frequency and temporal profile of poststroke hyperglycemia using continuous glucose monitoring.

OBJECTIVE: Poststroke hyperglycemia (PSH) is common and has adverse effects on outcome. In this observational study, we aimed to describe the frequency and temporal profile of PSH using a continuous glucose monitoring system (CGMS) in patients with and without diabetes. RESEARCH DESIGN AND METHODS: Fifty-nine patients with acute hemispheric ischemic stroke were prospectively studied with the CGMS, regardless of medication, admission plasma glucose value, and diabetes status. The CGMS records interstitial glucose every 5 min for 72 h. RESULTS: On admission, 36% of patients had preexisting diabetes. At the earliest analyzed time point of 8 h from stroke onset, 50% of nondiabetic subjects and 100% of diabetic patients were hyperglycemic (> or =7 mmol/l). This early-phase hyperglycemia was followed by a decrease in glucose 14-16 h poststroke when only 11% of nondiabetic and 27% of diabetic patients were hyperglycemic. A late hyperglycemic phase 48-88 h poststroke was observed in 27% of nondiabetic and 78% of diabetic patients. Thirty-four percent of nondiabetic and 86% of diabetic patients were hyperglycemic for at least a quarter of the monitoring period. Multivariate regression analysis demonstrated that diabetes, insular cortical ischemia, and increasing age independently predicted higher glucose values. CONCLUSIONS: Poststroke hyperglycemia is common and prolonged despite treatment based on current guidelines. There are early and late hyperglycemic phases in nondiabetic as well as diabetic patients. Treatment protocols with frequent glucose measurement and intensive glucose-lowering therapy for a minimum of 72 h poststroke need to be evaluated.

Aged↗
PubMed2005

Clinical-diffusion mismatch predicts the putative penumbra with high specificity.

BACKGROUND AND PURPOSE: Perfusion-diffusion (PWI-DWI) mismatch may represent the ischemic penumbra. The complexities associated with perfusion-weighted imaging (PWI) have restricted its use. Mismatch between stroke severity, assessed with the National Institutes of Health Stroke Scale (NIHSS), and the volume of the diffusion-weighted imaging (DWI) lesion (clinical-diffusion mismatch; CDM) has been suggested as a surrogate for PWI-DWI mismatch. We compared CDM with PWI and DWI in acute stroke. METHODS: Seventy-nine hemispheric stroke patients were imaged within 24 hours of symptom onset and subacutely (3 to 5 days). CDM was defined as NIHSS > or =8 and DWI < or =25 mL. DWI lesion and PWI (Tmax+4s) volumes were measured by planimetric techniques. Acute PWI-DWI mismatch was examined as a continuous variable (mismatch volume=PWIvol-DWIvol) and a categorical variable (mismatch=PWIvol-DWIvol/DWIvol x 100>20%). Early infarct expansion was calculated as DWI(subacute vol/DWI(acute vol). RESULTS: In the 54 sub-6-hour patients, CDM detected PWI-DWI mismatch with a specificity of 93% (95% confidence interval [CI], 62% to 99%), a positive predictive value of 95% (95% CI, 77% to 100%), but a sensitivity of only 53% (95% CI, 34% to 68%). Alternate DWI and NIHSS cutpoints did not improve test performance characteristics. In addition, subacute DWI expansion was significantly greater in patients with CDM (P=0.01) compared with those without. CONCLUSIONS: CDM (NIH > or =8, DWI < or =25 mL) predicts the presence of PWI-DWI mismatch with high specificity and low sensitivity. CDM also predicts DWI expansion. CDM may be a useful selection tool in acute stroke therapies, including thrombolysis.

Aged↗
PubMed2005

Gavestinel does not improve outcome after acute intracerebral hemorrhage: an analysis from the GAIN International and GAIN Americas studies.

BACKGROUND AND PURPOSE: Glycine Antagonist in Neuroprotection (GAIN) International and GAIN Americas trials were prospectively designed, randomized, placebo-controlled trials of gavestinel, a glycine-site antagonist and putative neuroprotectant drug administered within 6 hours of suspected ischemic or hemorrhagic stroke. Both trials reported that gavestinel was ineffective in ischemic stroke. This analysis reports the results in those with primary intracerebral hemorrhage. METHODS: The primary hypothesis was that gavestinel treatment did not alter outcome, measured at 3 months by the Barthel Index (BI), from acute intracerebral hemorrhage, based on pooled results from both trials. The BI scores were divided into 3 groups: 95 to 100 (independent), 60 to 90 (assisted independence), and 0 to 55 (dependent) or dead. RESULTS: In total, 3450 patients were randomized in GAIN International (N=1804) and GAIN Americas (N=1646). Of these, 571 were ultimately identified to have spontaneous intracerebral hematoma on baseline head computerized tomography scan. The difference in distribution of trichotomized BI scores at 3 months between gavestinel and placebo was not statistically significant (P=0.09). Serious adverse events were reported at similar rates in the 2 treatment groups. CONCLUSIONS: These observations from the combined GAIN International and GAIN Americas trials suggest that gavestinel is not of substantial benefit or harm to patients with primary intracerebral hemorrhage. These findings are similar to results previously reported in patients with ischemic stroke.

Acute Disease↗
PubMed2005

Recombinant activated factor VII for acute intracerebral hemorrhage.

BACKGROUND: Intracerebral hemorrhage is the least treatable form of stroke and is associated with high mortality. Among patients who undergo computed tomography (CT) within three hours after the onset of intracerebral hemorrhage, one third have an increase in the volume of the hematoma related to subsequent bleeding. We sought to determine whether recombinant activated factor VII (rFVIIa) can reduce hematoma growth after intracerebral hemorrhage. METHODS: We randomly assigned 399 patients with intracerebral hemorrhage diagnosed by CT within three hours after onset to receive placebo (96 patients) or 40 microg of rFVIIa per kilogram of body weight (108 patients), 80 microg per kilogram (92 patients), or 160 microg per kilogram (103 patients) within one hour after the baseline scan. The primary outcome measure was the percent change in the volume of the intracerebral hemorrhage at 24 hours. Clinical outcomes were assessed at 90 days. RESULTS: Hematoma volume increased more in the placebo group than in the rFVIIa groups. The mean increase was 29 percent in the placebo group, as compared with 16 percent, 14 percent, and 11 percent in the groups given 40 microg, 80 microg, and 160 microg of rFVIIa per kilogram, respectively (P=0.01 for the comparison of the three rFVIIa groups with the placebo group). Growth in the volume of intracerebral hemorrhage was reduced by 3.3 ml, 4.5 ml, and 5.8 ml in the three treatment groups, as compared with that in the placebo group (P=0.01). Sixty-nine percent of placebo-treated patients died or were severely disabled (as defined by a modified Rankin Scale score of 4 to 6), as compared with 55 percent, 49 percent, and 54 percent of the patients who were given 40, 80, and 160 microg of rFVIIa, respectively (P=0.004 for the comparison of the three rFVIIa groups with the placebo group). Mortality at 90 days was 29 percent for patients who received placebo, as compared with 18 percent in the three rFVIIa groups combined (P=0.02). Serious thromboembolic adverse events, mainly myocardial or cerebral infarction, occurred in 7 percent of rFVIIa-treated patients, as compared with 2 percent of those given placebo (P=0.12). CONCLUSIONS: Treatment with rFVIIa within four hours after the onset of intracerebral hemorrhage limits the growth of the hematoma, reduces mortality, and improves functional outcomes at 90 days, despite a small increase in the frequency of thromboembolic adverse events.

Adult↗
PubMed2004

Safety and feasibility of recombinant factor VIIa for acute intracerebral hemorrhage.

BACKGROUND AND PURPOSE: Hematoma growth occurs in 38% of intracerebral hemorrhage (ICH) patients scanned by computed tomography (CT) within 3 hours of onset. Activated recombinant factor VII (rFVIIa) promotes hemostasis at sites of vascular injury and may minimize hematoma growth after ICH. METHODS: In this randomized, double-blind, placebo-controlled, dose-escalation trial, 48 subjects with ICH diagnosed within 3 hours of onset were treated with placebo (n=12) or rFVIIa (10, 20, 40, 80, 120, or 160 microg/kg; n=6 per group). The primary endpoint was the frequency of adverse events (AEs). Safety assessments included serial electrocardiography (ECG), troponin I and coagulation testing, lower extremity Doppler ultrasonography, and calculation of edema:ICH volume ratios. RESULTS: Mean age was 61 years (range, 30 to 93) and 57% were male. At admission, mean National Institutes of Health Stroke Scale (NIHSS) score was 14 (range, 1 to 26), median Glasgow Coma Scale score was 14 (range, 6 to 15), and mean ICH volume was 21 mL (range, 1 to 151). Mean time from onset to treatment was 181 minutes (range, 120 to 265). Twelve serious AEs occurred, including 5 deaths (mortality 11%). Six AEs were considered possibly treatment-related, including rash, vomiting, fever, ECG T-wave inversion, and 2 cases of deep vein thrombosis (placebo and 20-microg/kg groups). No myocardial ischemia, consumption coagulopathy, or dose-related increase in edema:ICH volume occurred. CONCLUSIONS: This small phase II trial evaluated a wide range of rFVIIa doses in acute ICH and raised no major safety concerns. Larger studies are justified to determine whether rFVIIa can safely and effectively limit ICH growth.

Acute Disease↗
PubMed2004

Comparison of MRI and CT for detection of acute intracerebral hemorrhage.

CONTEXT: Noncontrast computed tomography (CT) is the standard brain imaging study for the initial evaluation of patients with acute stroke symptoms. Multimodal magnetic resonance imaging (MRI) has been proposed as an alternative to CT in the emergency stroke setting. However, the accuracy of MRI relative to CT for the detection of hyperacute intracerebral hemorrhage has not been demonstrated. OBJECTIVE: To compare the accuracy of MRI and CT for detection of acute intracerebral hemorrhage in patients presenting with acute focal stroke symptoms. DESIGN, SETTING, AND PATIENTS: A prospective, multicenter study was performed at 2 stroke centers (UCLA Medical Center and Suburban Hospital, Bethesda, Md), between October 2000 and February 2003. Patients presenting with focal stroke symptoms within 6 hours of onset underwent brain MRI followed by noncontrast CT. MAIN OUTCOME MEASURES: Acute intracerebral hemorrhage and any intracerebral hemorrhage diagnosed on gradient recalled echo (GRE) MRI and CT scans by a consensus of 4 blinded readers. RESULTS: The study was stopped early, after 200 patients were enrolled, when it became apparent at the time of an unplanned interim analysis that MRI was detecting cases of hemorrhagic transformation not detected by CT. For the diagnosis of any hemorrhage, MRI was positive in 71 patients with CT positive in 29 (P<.001). For the diagnosis of acute hemorrhage, MRI and CT were equivalent (96% concordance). Acute hemorrhage was diagnosed in 25 patients on both MRI and CT. In 4 other patients, acute hemorrhage was present on MRI but not on the corresponding CT--each of these 4 cases was interpreted as hemorrhagic transformation of an ischemic infarct. In 3 patients, regions interpreted as acute hemorrhage on CT were interpreted as chronic hemorrhage on MRI. In 1 patient, subarachnoid hemorrhage was diagnosed on CT but not on MRI. In 49 patients, chronic hemorrhage, most often microbleeds, was visualized on MRI but not on CT. CONCLUSION: MRI may be as accurate as CT for the detection of acute hemorrhage in patients presenting with acute focal stroke symptoms and is more accurate than CT for the detection of chronic intracerebral hemorrhage.

Acute Disease↗
PubMed2004

Perihematomal edema in primary intracerebral hemorrhage is plasma derived.

BACKGROUND AND PURPOSE: The mechanisms of perihematomal injury in primary intracerebral hemorrhage (ICH) are incompletely understood. An MRI study was designed to elucidate the nature of edema and blood flow changes after ICH. METHODS: Perihematomal blood flow and edema were studied prospectively with perfusion-weighted MRI (PWI) and diffusion-weighted MRI in 21 ICH patients. MRI and computed tomography (CT) images were coregistered to ensure perfusion and diffusion changes were outside of the hematoma. Edema volumes were measured on T2-weighted images. Apparent diffusion coefficient (ADC) values of the edematous regions were calculated. RESULTS: Mean patient age was 64.2 years (45 to 89), and median National Institutes of Health stroke scale score was 12 (3 to 24). Median time to MRI was 21 hours (4.5 to 110). Average hematoma volume on CT was 26.1 (4 to 84) mL. PWI demonstrated perihematomal relative mean transit time (rMTT) was significantly correlated with hematoma volume (r=0.60; P=0.004) but not edema volume. Perihematomal oligemia (rMTT >2 s) was present in patients with hematoma volumes of >15 mL (average rMTT 4.6+/-2.0 s). Perihematomal edema was present in all patients. ADC values within this region (1178+/-213x10(-6) mm2/s) were increased 29% relative to contralateral homologous regions. Increases in perihematomal ADC predicted edema volume (r=0.54; P=0.012) and this was confirmed with multivariate analysis. CONCLUSIONS: Acute perihematomal oligemia occurs in acute ICH but is not associated with MRI markers of ischemia and is unrelated to edema formation. Increased rates of water diffusion in the perihematomal region independently predict edema volume, suggesting the latter is plasma derived.

Aged↗
PubMed2004

Predictive thresholds for plague in Kazakhstan.

In Kazakhstan and elsewhere in central Asia, the bacterium Yersinia pestis circulates in natural populations of gerbils, which are the source of human cases of bubonic plague. Our analysis of field data collected between 1955 and 1996 shows that plague invades, fades out, and reinvades in response to fluctuations in the abundance of its main reservoir host, the great gerbil (Rhombomys opimus). This is a rare empirical example of the two types of abundance thresholds for infectious disease-invasion and persistence- operating in a single wildlife population. We parameterized predictive models that should reduce the costs of plague surveillance in central Asia and thereby encourage its continuance.

Animals↗
PubMed2004

Expression of a beta-defensin mRNA, lingual antimicrobial peptide, in bovine mammary epithelial tissue is induced by mastitis.

The expression of a beta-defensin, the lingual antimicrobial peptide (LAP), in response to mastitis was investigated by real-time PCR of RNA from mastitic and control udder quarters. There was a positive relationship between somatic cell count in milk and LAP expression. In situ hybridization showed that LAP mRNA was expressed in epithelial cells of mastitic tissue. These results suggest that LAP plays a role in the innate immune response to mastitis.

Animals↗
PubMed2004

Granulomatous lymphadenitis and splenitis associated with Monocillium indicum infection in a dog.

This report describes severe generalized granulomatous lymphadenitis and splenitis in a 5-year-old, spayed female, Rottweiler dog with anorexia and diarrhea. There was replacement or effacement of much of the parenchyma of the lymph nodes and spleen by sheets of macrophages, multinucleated giant cells, and myriad nonpigmented fungal organisms, most of which appeared to be intracellular. These organisms were very pleomorphic, including large chlamydospore-like cells, small round yeast-like cells, and septate hyphae. A fungus identified as Monocillium indicum was isolated from lymph node tissue. To the authors' knowledge, this is the first report of infection with Monocillium in either humans or other animals.

Animals↗