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Biomedical subjects

L J Crosby

Publications and source records attributed to L J Crosby.

8 recordsLinked to original sources
PubMed1997

Longitudinal sleep EEG power spectral analysis studies in adolescents with minor head injury.

Power spectral analysis (PSA) was used to evaluate the longitudinal overnight electroencephalographic (EEG) sleep recordings of eight subjects, between the ages of 15 and 19 years, who had sustained a minor head injury (MHI). Recordings occurred within 72 h, 6 weeks, and 12 weeks following MHI. A conditioning night preceded the first study night during which EEG electrodes were in place and subjects slept at least 7.5 h with a mean sleep efficiency of 91%. PSA was performed on four channels of EEG data recorded from fronto-temporal (F3-T3, F4-T4), and temporal (T3-T5, T4-T6) electrodes. The three waveforms associated with sleep, Delta, Theta, and Alpha-1 were all significantly elevated within 72 h post-MHI. Over time all wave forms decreased in mean log power. Theta in rapid eye movement (REM) sleep Cycle 1 decreased significantly within 6 weeks postinjury. The greatest number of significant changes, over the 12-week period were recorded during the non-REM (NREM) sleep. Changes included (1) significant decreases in mean log power of Theta and Alpha-1 in Cycle 1 from fronto-temporal leads; (2) significant decreases in Delta, Theta, and Alpha-1 in Cycle 2 from fronto-temporal leads, and (3) significant decreases in Delta and Theta for consistency during Cycle 2 from temporal leads. The intrusion of Theta into the first REM cycle within 6 weeks and its subsequent decrease within 6 weeks suggested the initiation of recovery toward baseline values. This was followed by decreased levels of Theta power during NREM Cycles 1 and 2, and Delta power in Cycle 2, both of which approached their lowest levels within 12 wks. The decrease in Alpha-1 power occurred last. Alpha-1 remained elevated through both Cycles 1 and 2 of the 6th week and then showed a precipitous decrease between the sixth and twelfth week. These findings suggested that following MHI, the brain has a specific sequence of recovery as illustrated by Delta, Theta, and Alpha-1 powers requiring different time frames to reach their lowest levels.

Adolescent↗
PubMed1992

Cerebrovascular response of closed head-injured patients to a standardized endotracheal tube suctioning and manual hyperventilation procedure.

The purposes of this research were to assess the cerebrovascular response of closed head-injured patients to a standardized endotracheal tube suctioning/manual hyperventilation (ETTS/MH) procedure and determine if a 5-minute rest period, following the ETTS/MH procedure, was sufficient in length to allow cerebrovascular parameters to return to pre-intervention levels. The sample consisted of 49 head-injured patients, 18 with a baseline mean intracranial pressure (MICP) of 7.1 mm Hg, standard error (SE) .6, and 31 with a baseline MICP of 9.3 mm Hg, SE .6. A total of 145 ETTS/MH procedures were completed, 51 within the lower baseline MICP group and 94 within the higher baseline MICP group. All data were collected within 72 hours of injury using a bedside component of the Hewlett-Packard Patient Monitoring System (H-P PMS). Computer programs written specifically for this research recorded physiologic data at specified points during baseline, throughout the ETTS/MH procedure and during the recovery period. A one-way repeated measures analysis of variance (ANOVA) was used to examine whether significant differences occurred over time during the baseline, intervention and recovery periods for each dependent variable. Significant F statistics were followed by nonorthogonal, multivariate planned comparisons using the Bonferroni posthoc test to identify significant differences between baseline and each 15 second measurement of all physiologic variables during the ETTS/MH procedure and at the end of each recovery minute over a 5-minute period. Independent t tests were used to assess between group differences at each data point throughout the procedure. Findings indicated those patients whose baseline MICP was most elevated demonstrated significantly (p less than .05) lower mean arterial blood pressure, cerebral perfusion pressure, and heart rate in response to the ETTS/MH procedure when compared to those patients with a lower baseline MICP. Additionally, 60 seconds of MH was required in both patient groups following the second and third suctioning catheter pass in order to reverse a step-wise increase in MICP. Finally, at least 2 full minutes of recovery time following the completion of the ETTS/MH procedure were required to allow all measured physiologic variables to return to baseline.

Adolescent↗
PubMed1991

Factors which contribute to fatigue associated with rheumatoid arthritis.

The purpose of this research was to identify the factors which people with rheumatoid arthritis (RA) believed contributed to their fatigue. A second purpose was to examine the relationships among identified factors and the sensation of fatigue. One hundred people with RA were asked to identify verbally factors which they believed contributed to their fatigue. The three most frequently identified factors included RA disease activity, disturbed sleep and increased physical effort. These factors were operationalized and measured as joint pain using the Modified McGill Pain Inventory, fragmented sleep through overnight electroencephalographic (EEG) sleep studies, and reduced physical ability using walking time and grip strength measures. Fifteen of the original subjects with RA and 12 age and gender matched control subjects completed the second phase of the research. Five of the RA subjects were experiencing a disease flare while the remaining 10 were either in remission or their disease was midly active. Those subjects in flare had significantly (P less than 0.01) more joint pain, significantly (P less than 0.05) more fragmented sleep, and significantly reduced functional capacity as measured through walking time (P less than 0.05) and grip strength (P less than 0.05) when compared to non-flare and control subjects. Fatigue levels of the subjects in flare were positively correlated with joint pain (r = 0.62), fragmented sleep (r = 0.42) and grip strength of the right hand (r = 0.52) and left hand (r = 0.88). Fatigue levels of non-flare and control subjects were negatively correlated with the majority of measured variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1988

Stress factors, emotional stress and rheumatoid arthritis disease activity.

The purpose of this study was to determine the relationship between stress factors, emotional stress and rheumatoid arthritis (RA) disease activity. Subjects (n = 101) confirmed to have RA completed the Daily Hassles Scale (DHS) to identify daily stress factors and the State/Trait Anxiety Inventory (STAI) as well as a visual analogue (VA) to measure emotional stress levels. The investigator evaluated RA disease activity (RADA) and erythrocyte sedimentation rate (ESR). Pearson product-moment correlation was used for statistical evaluation. A statistically significant, positive correlation was found between RADA and both measures of emotional stress; STAI r2 = 0.16, VA r2 = 0.25, P less than 0.01. Utilizing a psychophysiological feedback loop model, it was hypothesized that emotional stress levels and RA disease activity each served as a driving force and a consequence, i.e. as emotional stress levels increased, RA symptoms intensified and, likewise, as RA symptoms intensified, emotional stress levels increased. Nursing interventions were identified which possibly would reduce emotional stress levels, and thus, perhaps, decrease the incidence and/or severity of RA disease activity.

Adolescent↗
PubMed1982

The distribution and ultrastructure of sensory elements in the baroreceptor region of the truncus arteriosus of the lizard Trachydosaurus rugosus.

The proximal truncus arteriosus of the lizard Trachydosaurus rugosus was studied with light-, fluorescence- and electron-microscopical techniques. Three vessels comprised the truncus; the pulmonary, left aortic, and carotico-aortic arteries. Right and left truncal nerves, each derived from the ipsilateral vagus nerve, innervated the truncus, particularly its proximal 3 mm. Ultrastructurally, the nerves had a variety of appearances: some were clearly adrenergic, c-type or p-type. A number of profiles contained large numbers of mitochondria and were classified as sensory. Some profiles defied exact classification, having characteristics common to two different types of profile. Within the outer medial layers, profiles up to 7 micrometers in diameter were found. These contained large numbers of mitochondria, myelin bodies and structures intermediate between the two. In addition, the profiles contained large amounts of glycogen and small numbers of vesicles. These nerve fibres were classified as baroreceptors, since they closely resemble carotid sinus and aortic arch baroreceptors in mammals. Large numbers of chromaffin cells were found, particularly in the common wall of the pulmonary and left aortic arteries. Many of these cells emitted a long tapering process, which sometimes entered a nearby nerve bundle. Sensory, p-type and c-type profiles, but not adrenergic profiles, made extensive close contacts with chromaffin cells.

Animals↗