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D L Rotella

Publications and source records attributed to D L Rotella.

8 recordsLinked to original sources
PubMed2001

Old age affects fingertip forces when restraining an unpredictably loaded object.

We investigated the effects of old age on the fingertip force responses that occurred when a grasped handle was pulled unexpectedly to increase the tangential load at the fingertip. These automatic responses, directed normal to the handle surface, help prevent slips between the handle and finger. Old adults (average age 78 years) responded with large peak fingertip forces compared to young adults (average age 30 years), even though the two subject groups showed similar skin slipperiness. For step-shaped loads the average response latency was the same for young and old subjects (about 80 ms). Thus, these automatic responses are not susceptible to the age-related central delays known for simple reaction-time tasks. For ramp-shaped loads the average response latency was inversely related to load rate. Response latency was 25 ms longer for the Old group versus the Young group for loads of 8 N/s, and this difference increased exponentially to a 110-ms difference for 2-N/s loads. A twofold difference in the tangential force required to evoke a response was predicted from linear regressions and can account for the latency difference (0.2 N vs 0.4 N threshold for young and old, respectively, r=0.93 for both groups). This theoretical elevation in load force threshold is consistent with degraded central information processing in old age, and the deterioration of cutaneous mechanoreceptors.

Adult↗
PubMed1999

Mechanisms for age-related changes of fingertip forces during precision gripping and lifting in adults.

We investigated changes across the adult life span of the fingertip forces used to grip and lift objects and their possible causes. Grip force, relative safety margin (grip force exceeding the minimum to avoid slip, as a fraction of slip force), and skin slipperiness increased beginning at age 50 years. Skin slipperiness explained relative safety margin increases until age 60 years. Hence, after age 60 years, additional factors must elevate grip force. We argue that one factor is impaired cutaneous afferent encoding of skin-object frictional properties on the basis of three findings. First, only subjects 60 years and older increased their relative safety margins when the friction of the gripped surfaces was varied randomly versus experiments that varied only object weight. Skin slipperiness did not account for this behavior. Second, these older subjects scaled the initial portion of their force trajectories for the slippery surface during experiments when friction was varied. Third, their grip force adjustments to new surfaces were delayed approximately 100 msec as compared with young subjects. Previous research has demonstrated that friction is signaled locally by fast-adapting afferents (FA I afferents), which decrease in number during old age. By contrast, adjustments triggered by object set-down, an event encoded by FA II afferents throughout the hand and wrist, were not delayed in our old subjects. Other findings included that anticipatory control of fingertip forces using memory of object weight was unimpaired in old age. Finally, old and young adults modulated their fingertip forces with equal smoothness and with similar relative intertrial variability.

Adult↗
PubMed1998

Tactile impairments cannot explain the effect of age on a grasp and lift task.

This experiment addressed the often-posed theory that age-related declines in manual dexterity result from diminished tactile function. We measured the time 'young' subjects (n=33; mean=45 years) and 'old' subjects (n=33; mean=74 years) needed to grip (thumb and index finger), lift, and transport a small metal sphere when vision was permitted and when blindfolded. Subjects began each trial by reaching for the sphere and were instructed to complete the entire task quickly. In the absence of visual information, placement of the finger and thumb for a secure grip and lift cannot be performed efficiently without tactile information. If age-related tactile changes are functionally significant for this task, then without visual information the 'old' group should show a disproportionate increase in the duration of the grip and lift phase of the task compared to the 'young' group. Perceptual thresholds for tactile pressure stimuli (Semmes-Weinstein filaments) confirmed well-known age-related changes. Age and vision effects were manifest mainly during the grip-lift phase (time from object contact to lift-off from its support surface), with the expected finding that the 'old' group required more time than 'young' group, regardless of visual condition. The main finding was that the 'grip-lift' duration in the 'no-vision' condition was about twice the duration observed in the 'vision' condition for both age groups (ratios of 2.1 and 2.3 for 'young' and 'old', respectively). This similar relative slowing for the two groups fails to support the hypothesis that old adults' ability to grip and lift the object was limited by changes in the availability or use of tactile information.

Adult↗
PubMed1996

Staphylococcus aureus bacteremia: factors predicting hospital mortality.

Among 89 episodes of Staphylococcus aureus bacteremia, factors identified as independent predictors of hospital mortality were Acute Physiology and Chronic Health Evaluation III score > 60 (odds ratio [OR], 3.2; 95% confidence interval [CI95], 1.7 to 5.9) and Lifestyle score > 1 (OR, 2.1; CI95, 1.2 to 3.6). Future studies of S aureus bacteremia should take into consideration acute severity of illness (as well as treatment and source of infection) when evaluating outcome.

APACHE↗
PubMed1993

Clinical appropriateness, therapeutic equivalence, and cost of conversion of H2 antagonist therapy.

A 12-month drug monitoring program targeting the use of H2 antagonists was initiated at the Erie County Medical Center, a 650-bed academic teaching hospital in Buffalo, NY. Discussed in this article are the development of indicators used to determine appropriateness of therapy, implementation of a H2 antagonist monitoring and screening program, examination of the effect of the program on budgetary expenditures for H2 antagonist therapy, evaluation of adverse effects and potential drug interactions associated with drug use, and measurement of possible drug cost savings resulting from the implementation of the program.

Cimetidine↗
PubMedDate not supplied

Conversion of treatment from cefoxitin to ampicillin/sulbactam: experience in a university teaching hospital.

A 12-month trial, conducted in a 650-bed university teaching hospital, evaluated the conversion from cefoxitin to ampicillin/sulbactam. This report discusses the methodology used to evaluate the feasibility of the change and the challenges encountered during the trial period. The effect of cost and overall therapeutic outcome were other aspects of the evaluation. Results indicate that a conversion from cefoxitin to ampicillin/sulbactam is not only feasible but is also a realistic approach to achieving high-quality, cost-effective care.

Ampicillin↗