Biomedical subjects

Michael Tierney

Publications and source records attributed to Michael Tierney.

5 recordsLinked to original sources

PubMed2006

Hemispheric specialization in human prefrontal cortex for resolving certain and uncertain inferences.

Uncertainty is a fact of life that must be accommodated in real-world decision making. Although it has been suggested that the right prefrontal cortex (PFC) has a special role to play in decision making under uncertainty, there is very little hard data to support this hypothesis. To better understand the roles of left and right PFCs in reasoning and decision making in situations with complete and incomplete information, we administered simple inference problems to 18 patients with lateralized focal lesions to PFC (9 right hemisphere, 9 left hemisphere) and 22 age- and education-matched normal controls. The stimuli were systematically manipulated for completeness of information regarding the status of the conclusion. Our results demonstrated a 2-way interaction such that patients with left PFC lesions were selectively impaired in trials with complete information, whereas patients with right PFC lesions were selectively impaired in trials with incomplete information. These results provide compelling evidence for hemispheric specialization for reasoning in PFC and suggest that the right PFC has a critical role to play in reasoning about incompletely specified situations. We postulate this role involves the maintenance of ambiguous mental representations that temper premature overinterpretation by the left hemisphere.

Adult↗

PubMed2006

Genetic variability in CHMP2B and frontotemporal dementia.

A nonsense/protein chain-terminating mutation in the CHMP2B gene has recently been reported as a cause of frontotemporal dementia (FTD) in the single large family known to show linkage to chromosome 3. Screening for mutations in this gene in a large series of FTD families and individual patients led to the identification of a protein-truncating mutation in 2 unaffected members of an Afrikaner family with FTD, but not in their affected relatives. The putative pathogenicity of CHMP2B mutations for dementia is discussed.

Adult↗

PubMed2005

Neural correlates of script event knowledge: a neuropsychological study following prefrontal injury.

Scripts sequentially link information about daily activities and event knowledge. Patients have difficulty sequencing script events following lesions of the prefrontal cortex while showing intact access to selective aspects of script knowledge. It has been suggested that the sequencing impairment is due to a deficit in an inhibitory gating mechanisms that usually enables selection of an item from competing alternatives. If this is the case, then an inhibitory task should reveal script processing impairments on a script categorization task that is not normally associated with poor performance following prefrontal damage. To test this hypothesis, we administered a simple untimed classification task and a modified Go/NoGo task in which subjects classified events from social and non-social activities (e.g., read the menu, order the food) and related semantic items (e.g., menu, order) in terms of whether they belonged to a target activity. Participants were patients with lesions of the prefrontal cortex and matched controls. The results showed that damage to the right orbitofrontal cortex was associated with social item classification errors in the simple untimed classification task. In addition, the damage to the right prefrontal cortex was associated with increased response times to respond correctly to Go trials in the modified Go/NoGo task. The data demonstrate that damage to the right orbitofrontal cortex results in impairment in the accessibility of script and semantic representations of social activities. This impairment is exacerbated by an inefficient inhibitory gating mechanism.

Adult↗

PubMed2004

Standardization of intravenous insulin therapy improves the efficiency and safety of blood glucose control in critically ill adults.

OBJECTIVE: Aggressive glycemic control improves mortality and morbidity in critically ill adults, however implementation of such a strategy can be logistically difficult. This study evaluates the efficiency and safety of a nurse-managed insulin protocol in critically ill adults. DESIGN: Combined retrospective-prospective before-after cohort study. SETTING: Twenty-one bed, medical/surgical ICU in a tertiary care hospital. PATIENTS: Two cohorts of 50 consecutive ICU patients requiring insulin infusions. INTERVENTION: Patients in the control cohort received insulin infusions titrated according to target blood glucose ranges and sliding scales at the physician's discretion. Patients in the interventional cohort received an insulin infusion adjusted using a standardized protocol targeting a blood glucose of 4.5-6.1 mmol/l (81-110 mg/dl). MEASUREMENTS AND MAIN RESULTS: Efficiency was measured by comparing the time to reach, and the time spent within, the target range between cohorts. Safety was assessed by comparing the incidence of severe hypoglycemia, the frequency of rescue dextrose administration and the cumulative time that the infusion was held for hypoglycemia between cohorts. Patients in the interventional cohort reached their target more rapidly (11.3+/-7.9 vs 16.4+/-12.6 h; p=0.028) and maintained their blood glucose within the target range longer (11.5+/-3.7 vs 7.1+/-5.0 h/day; p<0.001) than controls. The standardized protocol yielded a four-fold reduction in the incidence of severe hypoglycemia (4 vs 16%; p=0.046) and reduced the median frequency of dextrose rescue therapy (0 [0-0.91] vs 0.17 [0-1.2] episodes/patient per day; p=0.01) as compared to controls. CONCLUSION: Standardization of intensive insulin therapy improves the efficiency and safety of glycemic control in critically ill adults.

Blood Glucose↗

PubMedDate not supplied

Adverse drug events in the elderly population admitted to a tertiary care hospital.

Older adults take almost one-third of the drugs prescribed today yet represent only about 12 percent of the population. Adverse drug events are common in this population, but often these events appear to be preventable. Interest in adverse events related to the use of prescription drugs has rarely been higher or broader. The research community continues to develop new tools to study adverse effects of drugs in individuals and populations. However, the published literature on drug-related adverse events is fraught with problems, starting with the original reports and extending to systematic reviews. Prospective data are missing, adverse drug events are poorly described, and analytical methods are questionable. This leads to problems with imprecise estimates and generalizability of results.

Adverse Drug Reaction Reporting Systems↗