Biomedical subjects

M Polk

Publications and source records attributed to M Polk.

15 recordsLinked to original sources

PubMed1998

Dementias that present with and without posterior cortical features: an important clinical distinction.

There are distinct qualitative differences between the dementias that present with and without posterior cortical features. These can be utilized in dementia assessment. This paper reviews the validity and potential utility of a dichotomy based on generalized cortical (Type 1) versus isolated frontal system pathology (Type 2). These syndromes are associated with distinct differentials and problem behaviors. They may also result in different caregiving burdens or treatment responses. Alzheimer's disease (AD) is by far the most common cause of the Type 1 syndrome. Type 2 presentations select for potentially reversible non-AD conditions. Common cognitive screening instruments are insensitive to Type 2 cases. However, the Type 1/Type 2 distinction can be made reliably using qualitative clinical rating scales. We will review these instruments and discuss their application in clinical settings.

Cerebral Cortex↗

PubMed1998

Esthetic orthodontic considerations for the adult patient: a general dentist's perspective.

Esthetic orthodontics is a viable treatment option for patients seeking cosmetic enhancement. Today, the use of preadjusted orthodontic brackets and straight wire allow general dentists to create optimum esthetic results in a short period of time. Two cases are presented to demonstrate a clinical technique to enhance a patient's smile through adjunctive orthodontic therapy.

Adult↗

PubMed1998

CLOX: an executive clock drawing task.

OBJECTIVE: To describe a clock drawing task (CLOX) designed to elicit executive impairment and discriminate it from non-executive constructional failure. SUBJECTS: 90 elderly subjects were studied (45 elderly and well persons from the independent living apartments of a continuing care retirement community and 45 patients with probable Alzheimer's disease). The clock drawing performance of elderly patients was compared with that of 62 young adult controls. METHODS: Subjects received the CLOX, an executive test (EXIT25), and the mini mental state examination (MMSE). The CLOX is divided into an unprompted task that is sensitive to executive control (CLOX1) and a copied version that is not (CLOX2). Between rater reliability (27 subjects) was high for both subtests. RESULTS: In elderly subjects, CLOX subscores correlated strongly with cognitive severity (CLOX1: r=-0.83 v the EXIT25; CLOX2: r=0.85 v the MMSE). EXIT25 and MMSE scores predicted CLOX1 scores independently of age or education (F(4,82)=50.7, p<0.001; R2=0.71). The EXIT25 accounted for 68% of CLOX1 variance. Only the MMSE significantly contributed to CLOX2 scores (F(4,72)= 57.2, p<0.001; R2=0.74). CLOX subscales discriminated between patients with Alzheimer's disease and elderly controls (83.1% of cases correctly classified; Wilkes' lambda=0.48, p<0.001), and between Alzheimer's disease subgroups with and without constructional impairment (91.9% of cases correctly classified; Wilkes' lambda=0.31, p<0.001). CONCLUSIONS: The CLOX is an internally consistent measure that is easy to administer and displays good inter-rater reliability. It is strongly associated with cognitive test scores. The pattern of CLOX failures may discriminate clinical dementia subgroups.

Adult↗

PubMed1993

Profiles of language impairment in primary progressive aphasia.

OBJECTIVE: The profile of language impairment in patients with primary progressive aphasia in comparison with the language impairment in patients with Alzheimer's disease and after stroke. DESIGN: The Western Aphasia Battery and the Mattis Dementia Rating Scale evaluated the language and cognitive impairment. Follow-up studies were done 1 to 5 years after the initial testing in seven of 10 patients with primary progressive aphasia, and a postmortem examination of the brain was done in two patients. SETTING: All 10 patients with primary progressive aphasia were previously healthy, community-dwelling persons when first tested. PATIENTS AND OTHER PARTICIPANTS: All patients with primary progressive aphasia reported at least a 2-year history of slowly progressive aphasia without other signs of global dementia. The initial Western Aphasia Battery results of the 10 patients with primary progressive aphasia were compared with those of a sample of 10 patients with probable Alzheimer's disease and with those of a sample of 10 patients with aphasia due to a left hemispheric stroke. Both reference samples were matched for age and sex; the sample with stroke-caused aphasia was additionally matched for the aphasia type. RESULTS: Expressive language disability with reduced speech fluency and anomia but preserved language comprehension and nonverbal cognition were typical features in early stages of primary progressive aphasia. Spontaneous speech was significantly more impaired in patients with primary progressive aphasia in comparison with those with aphasia after left hemisphere stroke and with language impairment in patients with Alzheimer's disease. Follow-up examinations revealed continuous, often rapid deterioration of language impairment. The neuropathological examination showed Alzheimer's disease in one patient and Pick's disease in the other. CONCLUSION: The profile of aphasia suggests that primary progressive aphasia tends to affect anterior parts of the language-dominant cortex first.

Aged↗

PubMed1993

Music and language in degenerative disease of the brain.

Music and language functions were studied in two musicians with degenerative disease. Both patients were tested on a standardized language battery and a series of music tasks. In the first case with left cortical atrophy and primary progressive aphasia, expressive music functions were spared with impaired reception of rhythm. The second case with posterior cortical atrophy, greater on the right, was nonaphasic, had spatial agraphia, a visuopractic deficit, and severe expressive music deficits, but intact rhythm repetition. The aphasic patient showed dissociations between music and language in fluency and content; continuous, organized, although reiterative music production was contrasted with nonfluent language. The nonaphasic patient showed the opposite pattern of deficits; unmusical production with impaired melody and rhythm organization that was contrasted with fluent, intelligible language. The double dissociation between language and music functions supports the existence of independent cognitive systems, one consistent with conventional left lateralization models of language, temporal sequence, and analytic music processing and another with a right lateralization model of implicit music cognition.

Agraphia↗

PubMed1993

The structural determinants of recovery in Wernicke's aphasia.

Recovery of comprehension and total language in 22 Wernicke's aphasics was correlated with lesion size and extent of involvement of certain structures on CT. Recovery rates and outcomes were separately examined using 0-3 months and 0-12 months poststroke language data. Quantitative measures of structural damage were regressed on total aphasia and comprehension outcome measures. Supramarginal and angular gyri appeared to be the most significant structures in recovery in addition to initial severity and lesion size. This was confirmed by using ANOVA to compare the extent of involvement in each postcentral structure among the poor, moderate, and good recovery groups. The superior temporal and middle temporal gyri are less involved in the good recovery group. Structures posteriorly adjacent to Wernicke's area are important for compensation in Wernicke's aphasia and in the accompanying comprehension deficit. Persisting Wernicke's aphasia usually involves the supramarginal and angular gyri in addition to the superior temporal area.

Aged↗

PubMed1992

Anatomical asymmetries and functional laterality.

Anatomical and functional asymmetries were measured using MRI and dichotic, visual field and hand performance laterality tasks in 104 normal right- and left-handed male and female adults. Comprehensive linear and area measures showed consistently larger brains when handedness and language laterality were in the same direction. Right-handers with left cerebral dominance for dichotic listening and left-handers with right cerebral dominance had larger structures. Hand performance was the strongest functional laterality related to anatomical asymmetries. Left hemisphere dominance on this task was associated with larger right frontal and left occipital widths. Dichotic listening or visual field laterality alone was not associated with contralaterally larger temporal, parietal or occipital measurements. Left visual field dominance for reading, interacting with right-handedness, was associated with wider left parietal width. The complex associations between anatomical and functional asymmetries contribute to individual differences in cerebral organization. The demonstrated association of coincident hand performance and language laterality measures with larger anatomical structures may confer biological advantage. Morphometric analysis in vivo may have increasing importance in interpreting behaviour.

Adult↗

PubMed1990

Sex, handedness, and the morphometry of cerebral asymmetries on magnetic resonance imaging.

Cerebral morphometry of linear measurements and hemispheric, frontal, temporal and parietal areas on MRI of 104 normal adults was analyzed for sex and handedness and right-left differences. The right hemisphere was significantly larger across all groups, but the left frontal width and area was larger in left handers. MANOVA showed separate effects of hand and sex for linear measures; right-handers had larger right anterior frontal, and left parietal and occipital widths. Ratios of L - R/L + R eliminated sex differences related to overall brain size, however, a significant sex-by-hand interaction was shown by the parietal area ratios, indicating larger left side in right-handed males and left-handed females. A 3-dimensional 'torque' was postulated, where the upper and rostral portions of the hemispheres were larger on the right and the lower and caudal parts equal, or slightly larger on the left. The relationship of anatomical asymmetries, sex and handedness is multi-dimensional, and may explain some of the variability of normal cognitive functions and deficits after brain damage.

Adolescent↗

PubMed1990

Cognition and white matter changes on magnetic resonance imaging in dementia.

In a prospective magnetic resonance imaging and cognitive study of 38 demented patients and 15 control subjects, 11 of 27 patients with Alzheimer's disease and 8 of 11 patients with vascular dementia had significant periventricular hyperintensities. Memory and language testing in the early investigation of dementia is useful to distinguish patients with or without periventricular hyperintensities on magnetic resonance imaging. Patients without periventricular hyperintensities are worse on memory and conceptualization tests than patients with periventricular hyperintensities, who tend to be worse on comprehension and attention tests. These differences in cognitive pattern are present between patients with different pathogenesis who are otherwise matched for dementia severity. Language and some nonverbal cognitive deficits correlate with the extent of cortical and ventricular atrophy in Alzheimer's disease.

Aged↗

PubMed1988

Antibodies against arylcyclohexylamines and their similarities in binding specificity with the phencyclidine receptor.

Rabbit antibodies were generated against five unique epitopes of phencyclidine (PCP)-like molecules to determine the molecular requirements for arylcyclohexylamine binding to the PCP receptor. Three of the haptens contained the three ring structures of PCP. A fourth hapten was synthesized from a derivative of the highly potent PCP analog, 1-[1-(2-thienyl)cyclohexyl]piperidine. The fifth hapten, 5-[N-(1'-phenylcyclohexyl)amino]pentanoic acid, was used as a haptenic model for N-ethyl-1-phenylcyclohexylamine, one of the most potent arylcyclohexylamines. These haptens were bound covalently to bovine serum albumin and were then used as antigens to immunize rabbits. The affinities and cross-reactivity patterns of the resulting five antibodies were studied in a [3H]PCP radioimmunoassay using standard curves of various arylcyclohexylamines. The dissociation constants ranged from 1.9 to 51.6 nM. From the average IC50 values of the radioimmunoassay dose-response curves, the relative potency of each ligand to PCP was determined. Least-squares linear regression was used to correlate these data with relative potency data from two [3H]PCP receptor binding assays and a PCP drug discrimination assay in the rat. Only relative potency data from the anti-5[N-(1'-phenylcyclohexyl)amino]pentanoic acid antibody showed a significant correlation with data from the three pharmacological studies (r2 = 0.80, 0.57 and 0.78, respectively; p less than .05 in all cases). These data indicated the 5-[N-(1'-phenylcyclohexyl)amino]pentanoic acid hapten contained the pharmacologically active features needed for arylcyclohexylamine binding to the PCP receptor.

Animals↗

PubMed1987

Cerebral dominance, sex, and callosal size in MRI.

We measured the MRI area of corpus callosum in 104 normal adults, 51 men, 53 women, 52 right- and 52 left-handers. There were no significant sex or handedness differences. Callosal areas did not correlate with brain size nor with measures of lateralization for hand performance, dichotic listening, or visual field preference. The results are contrary to the notion of increased callosal connectivity in left-handers, women, or individuals with less-lateralized function.

Adolescent↗

PubMed1986

Cerebral asymmetries on magnetic resonance imaging.

Magnetic Resonance Imaging (MRI) reveals anatomical asymmetries of the sulcal demarcation of the posterior operculum from the parietal cortex that correlate with handedness in normal subjects. The sulcal demarcation is greater on the right in most right handers, but evenly distributed in left handers. This in vivo asymmetry corresponds to the commonly larger planum temporale on the left side. Hand Preference, Hand Performance, Dichotic Listening and Visual Field Preference measures were correlated with several measures of anatomical asymmetries seen on MRI. The sulcal demarcation, anterior frontal width and parietal width correlated best with hand performance, as measured on a dot tapping task. The biological significance of the distribution of anatomical and functional asymmetries is discussed.

Adult↗

PubMed1977

The results of early operation in talipes quino-varus. A preliminary report.

The results of operation performed within the first six months of life upon seventy-seven resistant club feet are presented. The indications for and the rationale of early operation are discussed. Particular attention has been paid to the relationship between the age at operation and the outcome more than four years later; the results were greatly superior when operation was undertaken early. Two surgical techniques are compared, the postero-medial release proving better than a simple posterior release. The relationship between clinical and radiological assessment is discussed, and also the influence of the results reported upon future practice.

Age Factors↗

PubMedDate not supplied

Executive control and the comprehension of medical information by elderly retirees.

This study examined the independent contributions of executive control function, general cognition, age, education, and medication usage to the comprehension of medical information. Randomly selected elderly retirees (N = 105) more than 70 years of age completed the Executive Interview (EXIT25), the Mini-Mental State Exam (MMSE), and the Hopkins Competency Assessment Test (HCAT). Cognitive measures were stronger predictors of HCAT scores than age, education, or number of prescribed medications. A discriminant model based on EXIT25 and MMSE scores correctly classified 91% of subjects relative to their HCAT scores. It was concluded that executive impairment is strongly associated with impaired comprehension of medical information. As many as 88% of probable Alzheimer's disease patients, 69% of institutionalized elderly retirees, and 49% of noninstitutionalized retirees may be impaired in their ability to comprehend medical information, even when it has been presented well below their educational level.

Aged↗

PubMedDate not supplied

Anterior crossbite correction with fixed appliances in the adult dentition.

Anterior crossbite in the adult dentition, if not corrected, can cause other functional problems for the patient. These adult patients can be treated quickly and with confidence by most general dentists with the use of pre-adjusted appliances and straight wire. This article presents a clinical picture of three cases involving anterior crossbite correction in the adult patient with the use of fixed appliances and an acrylic splint.

Adult↗