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Biomedical subjects

R L Tate

Publications and source records attributed to R L Tate.

At least 19 recordsLinked to original sources
PubMed1999

Executive dysfunction and characterological changes after traumatic brain injury: two sides of the same coin?

This study examined the capacity of neuropsychological variables indicative of dysfunction in the regulation of executive abilities (e.g. noncompliance with rules) to reflect changes in character associated with disturbances in regulatory abilities (e.g. impulsivity). A close relative of 30 participants with traumatic brain injury (TBI) was administered the Current Behaviour Scale (CBS) at admission (rating premorbid character) and six months posttrauma (rating current character). The TBI group was examined neuropsychologically at six months posttrauma, along with 30 nonbrain-damaged (NBD) participants. Significant increases in CBS factors, Loss of Emotional Control and Loss of Motivation, occurred in the TBI group posttrauma. Differences between TBI and NBD groups were found for most executive variables. Those TBI participants with impairments on the neuropsychological Rule Breaking variable showed significant posttrauma increases in Loss of Emotional Control. There was also a trend for individuals with frontal lesions to make rule-breaking and perseverative errors.

Adolescent↗
PubMed1999

Psychosocial adjustment after traumatic brain injury: what are the important variables?

BACKGROUND: The common legacy of severe degrees of traumatic brain injury is varying degrees and types of impairments, which impact significantly upon the individual's resumption of pre-morbid psychosocial roles. Yet there are few data to indicate the relative contribution of these and other non-injury related variables. METHODS: Seventy individuals with varying levels of disability after severe traumatic brain injury were examined neurologically and neuropsychologically, on average at 6 years post-trauma. A range of biographical, injury, impairment and psychological variables were examined with multiple regression analyses to identify those that contributed to successful psychosocial reintegration. RESULTS: Severity of injury and impairments, along with chronicity and level of self-esteem were significant predictors of psychosocial adjustment. Further analyses revealed that within the neuropsychological domain, the variable measuring behavioural regulation of abilities was the most significant. Examination of specific domains of psychosocial functioning (occupational activities, interpersonal relationships and independent living skills) revealed different patterns of significant predictor variables, in addition to indices of the severity of initial injury: neurophysical impairments and memory functioning predicted successful occupational activities; chronicity, cognitive speed and behavioural regulation predicted success in interpersonal relationships; and neurophysical impairments, behavioural regulation and memory functioning predicted independent living skills. CONCLUSIONS: These results reinforce the overriding importance of injury severity and neurological factors (both neurophysical as well as neuropsychological) in predicting psychosocial adjustment after traumatic brain injury. Support for the contribution of non-neurological factors was also found.

Adaptation, Psychological↗
PubMed1998

Incidence of hospital-treated traumatic brain injury in an Australian community.

This paper reports findings from an incidence study of head trauma in a defined population. In the North Coast Health Region of NSW, 1,259 subjects with head trauma were admitted to hospitals in a 12-month period in 1988. Direct examination of the medical records confirmed brain injury in only 413 of these cases, corresponding to an annual incidence of approximately 100/100,000 resident population. Although most injuries (62.2%) were mild, 38% were serious (either moderate, 20.3%, or severe, 13.6%; and 3.9% died after admission to hospital). Severe brain injury represented an annual incidence of 12/100,000 resident population. Road traffic accidents accounted for a higher proportion of injuries in the severe group in comparison with the other injury groups. Methodological issues involved in case ascertainment of brain injury are discussed.

Adolescent↗
PubMed1997

Beyond one-bun, two-shoe: recent advances in the psychological rehabilitation of memory disorders after acquired brain injury.

Memory disorders are one of the most frequent types of cognitive impairment encountered in neurological populations. The more severe degrees of such impairment case major disability and handicap, and have a profound impact on a person's capacity to engage in independent living. To date, commonly used remediation strategies range from drills and practice, including computer-based tasks, to mnemonic techniques and memory notebooks. In general, these therapies have met with varying degrees of success. The last decade has seen exciting developments in remediation techniques for memory disorders, a number of which are based on implicit learning skills, as well as programmes tailored to an individual's unique pattern of deficits. The present paper provides an overview of this literature and discusses issues relating to their application in rehabilitation programmes.

Adult↗
PubMed1994

Error types in ideomotor apraxia: a qualitative analysis.

Seventeen brain-damaged subjects with dominant hemisphere pathology and 24 matched control subjects were asked to perform simple familiar gestures under four conditions: (1) verbal command (pantomime), (2) imitation, (3) with the actual object, and (4) verbal command a second time. The subjects subsequently watched a video of an actor performing simple movements and decided whether or not these were performed accurately. The gestural production task was videoed and analyzed for error type. Error type remained consistent over the four task conditions, although subgroups of patients made different types of errors. One group of patients with Ideomotor Apraxia (IMA) made more errors but of the same type as the controls, i.e., movement-related errors and the use of "body part as object" (BPO). The second group made mainly substituted (i.e. unrelated) movements and perseverative errors. The second group of subjects was also poorer at discriminating incorrectly performed movements in the recognition task. BPO errors were commonly made by the control group and they were also chosen as correct in the recognition task. This indicated that use of BPO may reflect a convention in symbolising gestures rather than pathology. The performance of the IMA subjects was discussed in relation to current theories of the mechanisms underlying apraxia.

Adult↗
PubMed1993

Analyzing individual status and change with hierarchical linear models: illustration with depression in college students.

A recently developed class of multilevel or hierarchical linear models (HLM) provides an intuitive and efficient way to estimate individual growth or change curves. The approach also models the between-subjects variation of the individual change curves with treatment factors and individual attributes. Unlike other repeated measures analysis methods common in the behavioral sciences, HLM allows the fit of data with unequal numbers of repeated observations for each subject, variable timing of observations, and missing data, features which are often characteristic of data from field studies. The application of HLM for the analysis of repeated psychological measures is discussed and illustrated here with depression data for college students. Strengths and limitations of the approach are discussed.

Adaptation, Psychological↗
PubMed1991

Patterns of neuropsychological impairment after severe blunt head injury.

A consecutive series of 100 subjects with severe blunt head injuries was followed up 6 years after trauma. Neuropsychological test performances of 82 subjects and of a noninjured control group were analyzed by two principal components analyses (PCAs). Each PCA extracted 15 factors relating to a range of cognitive impairments, as well as neuropsychological features consistent with posttraumatic personality changes. Measures identified by the PCAs were applied to 85 head-injured subjects in the series to examine the incidence of impairment in four neuropsychological areas: disorders of learning and memory, neuropsychological features consistent with posttraumatic personality change, slowness in rate of information processing, and a range of basic neuropsychological skills. Overall, impairments occurred in 70% of the series. Disorders of learning and memory were the most common type of deficit (56.5%), with disturbances in basic neuropsychological skills the least frequent (16.5%). Variability among subjects with respect to the types and combinations of neuropsychological impairments was a characteristic feature of this clinical group, but the largest proportion (one-third) demonstrated isolated impairments. The implications of the incidence and selectivity of neuropsychological impairments are discussed.

Adolescent↗
PubMed1990

Sodium cholate-induced changes in the conformation and activity of rat pancreatic cholesterol esterase.

Pancreatic cholesterol esterase (CEase) regulates dietary cholesterol absorption and is activated in the presence of trihydroxy bile salts while remaining inactive monohydroxy bile salts. CEase from rat pancreas has been purified by ammonium sulfate precipitation, hydroxylapatite chromatography, and gel filtration on Sephacryl S-200/S-300 columns connected in series, and its homogeneity and Mr (55,418 +/- 288) have been determined by sedimentation equilibrium centrifugation. The effects of tri-, di-, and monohydroxy bile salts on the conformation of the purified enzyme in buffer solution and in an in vitro assay system were studied by circular dichroism spectropolarimetry. The CD spectrum of the enzyme in solution shows a curve shape suggestive of an alpha-helicity, but low mean residue ellipticity (MRE) values may indicate an important beta-turn contribution. Sodium cholate, a trihydroxy bile salt, induces a decrease in the negative MRE values of the enzyme in solution at bile salt concentrations of 70-100 nM, with no further spectral changes at concentrations as high as 1 mM. Sodium cholate concentrations higher than 1 microM also induce an increase in the enzyme's negative MRE values under activity assay conditions, which reverts toward its original value once the reaction reaches equilibrium. These latter changes are interpreted as induced by substrate binding to the enzyme followed by partial substrate depletion after the reaction reaches equilibrium. Sodium deoxycholate, a dihydroxy bile salt, induces unstable transient increases and decreases in the MRE values of CEase in buffer solution and under activity assay conditions. These changes are bile salt concentration-dependent and may reflect self-association of the protein. Sodium taurolithocholate, a monohydroxy bile salt, does not affect the CD spectrum of CEase, and neither the di- or the monohydroxy bile salt activates the enzyme.

Animals↗
PubMed1989

Transduction heats in retinal rods: tests of the role of cGMP by pyroelectric calorimetry.

The sensory dark current of vertebrate retinal rods is believed to be controlled by light activation of a chain of coupled biochemical cycles that finally regulate the cationic conductance of the plasma membrane by hydrolytically reducing the level of cGMP in rod outer segment cytoplasm. The scheme has been tested by measuring heat production by live frog retinas when stimulated with sequences of light flashes of progressively increasing energy. Using pyroelectric poly(vinylidene 1,1-difluoride) detectors that simultaneously measure transretinal voltage and retinal temperature change, four heat effects assignable to known biochemical cycles in rods have been found. As the dark current shuts down after a flash causing 180-1800 rhodopsin photoisomerizations per rod, a heat burst, q1, raises the retinal temperature 1-2 microK. q1 is closely regulated in size and slightly precedes dark current shutdown. Isobutylmethylxanthine slows and enlarges q1, delaying the dark-current response. Increasing cytoplasmic Ca2+ stops the dark current without affecting q1. Although rod heat production is consistent with splitting of 1-3 microM of free cytoplasmic cGMP during transduction, the kinetics of the two processes do not match the predictions of current cGMP control models.

Animals↗
PubMed1989

Impairment after severe blunt head injury: the results from a consecutive series of 100 patients.

Three scales, assessing the degree of brain impairment after severe blunt head injury in neurophysical and neuropsychological functions as well as overall organic functioning, are described. A consecutive series of 100 severe blunt head injured patients was followed up 6 years post-trauma and the scales were used to measure the residual impairments and determine the level of recovery for 82 subjects in the series. No subject made a complete neurophysical and neuropsychological recovery, 92% of the series was classified as suffering clinically significant impairments and in half the series the moderate or severe impairments were consistent with a poor level of recovery. The impairments of a large proportion (42%) of the series, however, were classified as mild. Although most subjects demonstrated impairments in both neurophysical and neuropsychological functions, 43% of the series suffered isolated impairments in either the neurophysical or neuropsychological areas. There was strong agreement between the overall organic impairment profile and the subjects' classifications on the Glasgow Outcome Scale.

Adolescent↗
PubMed1989

DNA restriction patterns and DNA-DNA solution hybridization studies of Frankia isolates from Myrica pennsylvanica (bayberry).

Sixteen Frankia strains were isolated from Myrica pennsylvanica (bayberry) root nodules collected at diverse sites in New Jersey. Restriction pattern analysis of total genomic DNA was used to group the isolates into gel groups, and the genetic relatedness among the isolates was evaluated by DNA-DNA solution hybridization studies. Restriction pattern analysis provided a distinctive reproducible fingerprint for each isolate. Isolates fell into nine separate groups (strain types). More than one strain type was isolated from most sites. Isolates from two different gel groups were found in 3 of 10 nodules examined. Of the 16 isolates, 10 contained extrachromosomal DNA. Six different extrachromosomal DNA banding patterns were found. Genomically similar isolates carried related, but different, banding patterns. DNA hybridization studies indicated that isolates from a single plant species can be minimally related as determined by total genome homology. Homology ranged from 12 to 99%. Highly divergent strains were isolated from the same plant and found to cohabit the same nodule. Thus, this study demonstrated that Frankia strains which infect the same host plant are not only phenotypically different but also genetically diverse.

Actinomycetales↗
PubMed1989

Physiological, chemical, morphological, and plant infectivity characteristics of Frankia isolates from Myrica pennsylvanica: correlation to DNA restriction patterns.

The filter exclusion method was used to isolate Frankia strains from Myrica pennsylvanica (bayberry) root nodules collected at diverse sites in New Jersey. A total of 16 isolates from five locations were cultured. The isolates were characterized by morphological, chemical, physiological, and plant infectivity criteria and compared with genomic DNA restriction pattern data, which were used to assign the isolates into gel groups (see accompanying paper). The isolates from M. pennsylvanica evaluated in this study were characteristic of Frankia physiological group B strains and were indistinguishable on the basis of whole-cell wall chemistry and diaminopimelic acid isomer analysis. Distinct differences in the spectrum of utilized organic acids and carbohydrates were observed among the isolates and were the only phenotypic criteria by which the isolates could be separated and assigned into separate groups. In general, isolates within a restriction pattern gel group had identical utilization patterns, whereas intragroup isolates had different utilization patterns. Correlation of these phenotypic characteristics with the results of molecular analysis revealed an exclusive carbohydrate and organic acid utilization pattern for each gel group as established by restriction pattern analysis.

Actinomycetales↗
PubMed1989

Psychosocial outcome for the survivors of severe blunt head injury: the results from a consecutive series of 100 patients.

A consecutive series of 100 severely blunt head injured subjects was followed up six years after trauma and the level of psychosocial reintegration was determined for 87 subjects. Three-quarters of the series were classified as demonstrating major disability, having either a Poor Reintegration (33%) or a Substantially Limited Reintegration (43%); the remaining one-quarter of the series attained a Good Reintegration. The level of reintegration was related to the Glasgow Outcome Scale classification, although a one-to-one correspondence between the Glasgow Outcome Scale and the Psychosocial Disability Scale was not found: each of the Moderate Disability and Good Recovery groups was fairly evenly divided between a better and worse level of reintegration. Specific aspects of the subjects' psychosocial reintegration in employment, interpersonal relationships, functional independence, social contacts and leisure interests are described and the implications of the findings for the provision of extended care services to meet the long term needs are discussed.

Adolescent↗
PubMed1987

Issues in the management of behaviour disturbance as a consequence of severe head injury.

The management of organic psychosocial deficit following severe head injury has been a neglected area of rehabilitation. Behavioural modification programmes are being utilised increasingly to ameliorate inappropriate behaviours within the rehabilitation framework. Patterns of organic psychosocial deficits in the head injured are described and issues in the management of behaviour disturbances and the constraints that operate in the application of psychological techniques to the population who suffer acquired brain damage are discussed.

Aphasia↗
PubMed1987

Behaviour management techniques for organic psychosocial deficit incurred by severe head injury.

Subgroups of severe head injured patients exhibit patterns of organic psychosocial deficits resulting in behavioural disturbances. Behavioural management techniques are discussed and two case illustrations are presented in detail: a physically disabled but cognitively well preserved patient who refused to cooperate with therapy programmes; and a permanently severely physically and cognitively disabled patient who screamed and was assaultive whenever physical proximity or contact occurred.

Adolescent↗
PubMed1978

Cultural and environmental factors affecting the longevity of Escherichia coli in Histosols.

The survival of Escherichia coli in organic soils (Histosols) was examined. The death rate of this organism in Pahokee muck was less than that observed in Pompano fine sand. The number of viable E. coli cells found in the muck was approximately threefold greater than that found in the sand following 8 days of incubation. The initial population of the coliform affected the death rate. The rate of loss of viability varied 100-fold when the population size decreased from 2.5 x 10(7) to 3.4 x 10(4). Other factors affecting the viability of E. coli in muck were aerobic versus anaerobic growth of the organism and moist versus flooded conditions in the soil. The greatest survival of the coliform was noted with anaerobically grown cells amended to flooded soil. That the observed decrease in E. coli viability in soil was the result of biotic factors was demonstrated with amendment of sterile soil with E. coli. When 1.1 x 10(5) bacteria per g of soil were added to sterile muck, a population of 3.0 x 10(7) organisms per g of soil developed over a 10-day period. The role of the protozoa in eradication of the coliform from the muck was indicated by a sixfold increase in the protozoan population in natural soil amended with E. coli. Higher organic matter content in a Histosol compared with a mineral soil resulted in an increased survival of the fecal coliforms. Biotic factors are instrumental in the decline in coliform populations, but the potential for growth of the coliform in the organic soil could extend the survival of the organism.

Aerobiosis↗
PubMed1977

Nitrification in histosols: a potential role for the heterotrophic nitrifier.

Insufficient populations of Nitrosomonas and Nitrobacter were found in a Pahokee muck soil (Lithic medidaprit) to account for the nitrate concentration observed. To determine if heterotrophic nitrifiers could account for some of this discrepancy, a method was developed to measure the levels of heterotrophic nitrifiers in soil. A population of 4.1 X 10(5) Arthrobacter per g of dry fallow soil, capable of producing nitrite and/or nitrate from reduced nitrogenous compounds, was observed. Amendment of the much with 0.5% (wt/wt) sodium acetate and 0.1% (wt/wt) ammonium-nitrogen as ammonium sulfate (final concentrations) not only resulted in the usual increase in autotrophic nitrifiers, but also in a fourfold increase in the heterotrophic nitrifying Arrthrobacter. Amendment of like samples with N-Serve [2-chloro-6(trichloromethyl) pyridinel] prevented the increase in Nitrosomonas, but not that in the heterotrophic nitrifiers. Nitrate production in the presence of the inhibitor was diminished but not prevented. An Arthrobacter sp., isolated from the muck, produced nitrite when inoculated at high densities into sterile soil, unamended or amended with sodium acetate and/or ammomium sulfate. These data suggest that the heterotrophic population may be responsible for some of the nitrate produced in these Histosols.

Acetates↗