PubMed Health⌕ Search

Biomedical subjects

T M Scott

Publications and source records attributed to T M Scott.

At least 19 recordsLinked to original sources
PubMed1996

Severe cardiovascular disease and Alzheimer's disease: senile plaque formation in cortical areas.

The main objectives of this study were to analyze the distribution of senile plaques (SP) and neurofibrillary tangles (NFT) in different cortical areas of patients suffering from severe cardiovascular diseases (CVD) and to compare them with Alzheimer's disease (AD) cases. Forty brains were divided into three groups: an AD group (n = 12), a CVD group (n = 17), and a nonheart disease control group (n = 11). The cortical areas examined were the middle frontal gyrus, the superior and inferior watershed areas, the hippocampal formation with the transentorhinal cortex, and the primary visual cortex. SP and NFT were counted in Bielschowsky-stained sections from all cortical areas and from the hippocampal formation and the transentorhinal cortex, respectively. Patients with severe CVD occupied an intermediate position in the spectrum of SP formation between AD and nonheart disease patients. The CVD group showed a higher prevalence of SP than the control group, and SP counts were significantly larger in the inferior watershed area, dentate gyrus, subiculum, and transentorhinal cortex. The distribution of SP was similar in CVD and AD patients. Control and CVD patients showed no difference regarding the number of NFT. The existence of a possible cardiovascular component in the genesis of SP is discussed.

Aged↗
PubMed1996

Dynamic susceptibility contrast MRI of regional cerebral blood volume in Alzheimer's disease.

OBJECTIVE: The purpose of this study was to investigate the potential effectiveness of dynamic susceptibility contrast magnetic resonance imaging (MRI) to discriminate elderly patients with Alzheimer's disease from normal matched comparison subjects. METHOD: Images of regional cerebral blood volume (CBV) were generated from echo-planar MRI with the dynamic susceptibility contrast method in 13 Alzheimer's disease patients and 13 comparison subjects group-matched on age and gender. RESULTS: Temporoparietal cerebral blood volume, expressed as a percentage of the cerebellum value, was reduced 17% bilaterally in the patients with Alzheimer's disease. Blood volume in sensorimotor regions was reduced only 8.5% in the patients. Discriminant function analysis based on left and right temporoparietal measures correctly classified 88.5% of the subjects as patients or comparison subjects. Temporoparietal CBV was reduced even in mildly affected Alzheimer's disease patients (Mini-Mental State scores > 24). CONCLUSIONS: Dynamic susceptibility contrast MRI of regional CBV is promising as a nonradioactive, potentially lower-cost alternative to other functional neuroimaging methods for evaluating Alzheimer's disease.

Aged↗
PubMed1995

Deficits in short-term memory in adult survivors of childhood abuse.

Exposure to stress has been associated with alterations in memory function, and we have previously shown deficits in short-term verbal memory in patients with a history of exposure to the stress of combat and the diagnosis of posttraumatic stress disorder (PTSD). Few studies of any kind have focused on adult survivors of childhood physical and sexual abuse. The purpose of this study was to investigate short-term memory function in adult survivors of childhood abuse. Adult survivors of severe childhood physical and sexual abuse (n = 21), as defined by specific criteria derived from the Early Trauma Inventory (ETI), who were presenting for psychiatric treatment were compared with healthy subjects (n = 20) matched for several variables including age, alcohol abuse, and years of education. All subjects were assessed with the Wechsler Memory Scale (WMS) Logical (verbal memory) and Figural (visual memory) components, the Verbal and Visual Selective Reminding Tests (SRT), and the Wechsler Adult Intelligence Scale-Revised (WAIS-R). Adult survivors of childhood abuse had significantly lower scores on the WMS Logical component for immediate and delayed recall in comparison to normal subjects, with no difference in visual memory, as measured by the WMS or the SRT, or IQ, as measured by the WAIS-R. Deficits in verbal memory, as measured by the WMS, were associated with the severity of abuse, as measured by a composite score on the ETI. Our findings suggest that childhood physical and sexual abuse is associated with long-term deficits in verbal short-term memory. These findings of specific deficits in verbal (and not visual) memory, with no change in IQ, are similar to the pattern of deficits that we have previously found in patients with combat-related PTSD.

Adult↗
PubMed1995

Effect of denervation of the rat superior mesenteric arterial bed on the distribution of resistance among the first four orders of branching.

The rat superior mesenteric artery with its first four orders of branching has been examined as an isolated perfused preparation. Lumen diameter and proportional resistance at each level have been determined and compared under conditions of constant pressure following methoxamine-induced constriction and acetylcholine-induced relaxation in intact and denervated preparations. A comparison was also made between intact preparations under conditions of constant pressure and constant flow. Lumen diameter and segment length were measured by analysis of video-taped images. The distribution of resistance among the first four orders of branching was estimated from the measured values using the Poiseuille formula. Intact first and fourth order branches had a proportionately low resistance, with the remaining resistance being fairly evenly distributed between the second and third order branches. No change in the pattern occurred as a result of either methoxamine or acetylcholine treatment. The pattern of distribution of resistance changed following denervation, so that proportional resistance was high in the first order branches and fell off from the second to fourth order branches. With methoxamine, the first order branches of denervates had a significantly higher resistance than in intact tissues, with the distribution of resistance in the second to fourth order branches following the basal resistance pattern. Reduction in the proportion of resistance with acetylcholine was similar in both intact and denervated preparations. Distribution of resistance did not differ between constant flow and constant pressure intact preparations.

Acetylcholine↗
PubMed1995

MRI-based measurement of hippocampal volume in patients with combat-related posttraumatic stress disorder.

OBJECTIVE: Studies in nonhuman primates suggest that high levels of cortisol associated with stress have neurotoxic effects on the hippocampus, a brain structure involved in memory. The authors previously showed that patients with combat-related posttraumatic stress disorder (PTSD) had deficits in short-term memory. The purpose of this study was to compare the hippocampal volume of patients with PTSD to that of subjects without psychiatric disorder. METHOD: Magnetic resonance imaging was used to measure the volume of the hippocampus in 26 Vietnam combat veterans with PTSD and 22 comparison subjects selected to be similar to the patients in age, sex, race, years of education, socioeconomic status, body size, and years of alcohol abuse. RESULTS: The PTSD patients had a statistically significant 8% smaller right hippocampal volume relative to that of the comparison subjects, but there was no difference in the volume of other brain regions (caudate and temporal lobe). Deficits in short-term verbal memory as measured with the Wechsler Memory Scale were associated with smaller right hippocampal volume in the PTSD patients only. CONCLUSIONS: These findings are consistent with a smaller right hippocampal volume in PTSD that is associated with functional deficits in verbal memory.

Adult↗
PubMed1994

A case-based anatomy course.

A course is described in which the students give consideration to clinical cases as they review their current knowledge, and follow a set protocol which guided them in preparing their learning. The students are required to examine a case history, put down as key words either their first answer or the knowledge they consider they would need to answer specific questions. They then select stations at which additional information, wet specimens, models and radiological images assist them in upgrading their knowledge. They complete the exercise by writing a final answer to the questions on the case. The tutor is able through examination of the key words to determine the knowledge of the students as they enter, and confirm appropriate learning by inspection of the final answer. The students are able to identify their own deficiencies, develop strategies for thinking and learning, resulting in the acquisition of expertise in problem solving, and extend their communication skills by working with colleagues. While the course was designed for second-year anatomy teaching it could be applied to other disciplines.

Anatomy↗
PubMed1994

The involvement of CGRP in acetylcholine-induced vascular relaxation.

Earlier work on peptidergic fibres suggested some involvement of CGRP perivascular nerve fibres in acetylcholine-induced endothelium-dependent vascular relaxation. We have investigated the effect of blocking CGRP receptors and CGRP replacement on acetylcholine-induced endothelium-dependent vascular relaxation in the isolated perfused mesenteric arterial bed in normal Sprague-Dawley rats and in rats seven days following freeze-denervation of the superior mesenteric artery. Freeze-denervation was carried out under pentobarbital anesthesia (40 mg/Kg). It was found that the ability of acetylcholine to cause relaxation was reduced by CGRP receptor blocking with CGRP8-37 in vessels from control rats, but returned to pre-blocking levels after washout of the antagonist. Treatment with CGRP increased the relaxation due to acetylcholine in denervated vessel beds, but not in control tissues. The CGRP receptor appears to be involved in the acetylcholine-induced relaxation of blood vessels. The mechanism of action is not known, although both acetylcholine and CGRP, act through activation of K+ channels, and CGRP may facilitate the activation of K+ channels by acetylcholine.

Acetylcholine↗
PubMed1994

The involvement of perivascular innervation in acetylcholine-induced endothelium-dependent vascular relaxation in the rat superior mesenteric arterial bed.

The distribution of the ability of perivascular peptidergic innervation to influence acetylcholine-induced relaxation in the arterial bed has been investigated using the superior mesenteric arterial bed of the rat. The superior mesenteric artery was denervated by freezing, under pentobarbital anaesthesia (40 mg/kg i.p.), at one of two different points and the animals allowed to survive for 7, 14, 21 or 28 days following freezing. This produced a range of denervation along the superior mesenteric artery and its branches. The ability to respond to acetylcholine in an endothelium-dependent fashion was determined pharmacologically in isolated perfused superior mesenteric artery preparations. The extent of the denervation was determined by immunohistochemistry. It was found that the ability of the arterial bed to relax in a concentration-dependent manner to increasing concentrations of acetylcholine was little altered by denervation of the superior mesenteric artery alone. However when a short piece of the superior mesenteric artery and its primary branches were denervated the response to acetylcholine was reduced. It is concluded that the innervation of the primary branches of the mesenteric artery, the jejunal and ileal branches, contributes to the ability of acetylcholine to cause endothelium-dependent relaxation.

Acetylcholine↗
PubMed1994

The L-name-resistant component of acetylcholine-induced relaxation of the rat superior mesenteric arterial bed is innervation-dependent.

Using L-NAME and the potassium channel blocker apamin we have investigated the component of acetylcholine-induced vascular relaxation lost when the mesenteric arterial bed is denervated. We have confirmed that vascular denervation produces a reduction of up to 35% in the ability of ACh to cause relaxation in the presence of the alpha agonists methoxamine and cirazoline. A single 30 minute exposure to L-NAME reduced the relaxation to ACh by up to 44% in control vascular preparations and by 85% in denervated preparations. In control preparations, prolonged exposure to L-NAME reduced the relaxation to ACh by up to 66% and by 77% in the presence of apamin. In denervated preparations prolonged exposure to L-NAME reduced the relaxation to ACh by 96%. The almost complete loss of acetylcholine-induced relaxation following prolonged exposure to L-NAME (96.6% in methoxamine and 93.9% in cirazoline) in denervated preparations suggests that innervation is involved in the expression of the L-NAME-resistant relaxation to acetylcholine in the superior mesenteric arterial bed of the rat.

Acetylcholine↗
PubMed1993

Deficits in short-term memory in posttraumatic stress disorder.

OBJECTIVE: The purpose of this study was to compare the memory function of patients with posttraumatic stress disorder (PTSD) to that of matched comparison subjects. METHOD: Vietnam veterans with combat-related PTSD (N = 26) were compared to physically healthy comparison subjects (N = 15) matched for age, race, sex, years of education, handedness, socioeconomic status, and alcohol abuse. Memory and intelligence were assessed with a battery of neuropsychological tests, including the Russell revision of the Wechsler Memory Scale, the Selective Reminding Test, and subtests of the Wechsler Adult Intelligence Scale-Revised (WAIS-R). RESULTS: The PTSD patients scored significantly lower than the comparison subjects on the Wechsler Memory Scale logical memory measures for immediate recall (mean = 11.6, SD = 3.3 versus mean = 20.9, SD = 6.6) and delayed recall (mean = 8.0, SD = 3.3 versus mean = 17.8, SD = 6.4). The PTSD patients also scored significantly lower on the total recall, long-term storage, long-term retrieval, and delayed recall measures for the verbal component of the Selective Reminding Test and on the recall, long-term storage, long-term retrieval, and continuous long-term retrieval measures for the visual component of the Selective Reminding Test. There was no significant difference between the PTSD patients and comparison subjects in prorated full-scale IQ as measured by the WAIS-R. CONCLUSIONS: Patients with PTSD may have deficits in short-term memory. Counseling and rehabilitation that address these deficits may be of value for PTSD patients.

Humans↗
PubMed1993

How we teach anatomy efficiently and effectively.

An anatomy course is presented which stresses the teaching of applied anatomy using lectures, laboratory workshops and problem-solving tutorials. Laboratory workshops include the use of prosected specimens and body imaging such as CT scan and ultrasound, but do not include dissection. The problem-solving tutorials make extensive use of clinical cases and the application of anatomical knowledge. The course is taught by anatomists and practising physicians, and needs only 98 hours of curriculum time. The performance of the students and the positive attitudes of both students and faculty are enhanced by the design of the course.

Anatomy↗
PubMed1992

Quantitative magnetic resonance imaging in temporal lobe epilepsy: relationship to neuropathology and neuropsychological function.

Magnetic resonance images (MRIs) were obtained from 25 patients with medically refractory epilepsy of temporal lobe origin (12 on the left, 13 on the right) and 14 right-handed control subjects. The hippocampi and temporal lobes were traced by computer on successive coronal images and the resulting measurements of area were summed for each region. The left and right hippocampi were symmetrical in the control subjects; however, for patients the hippocampus was smaller on the side of the seizure focus. Moreover, the left-right hippocampal ratio significantly differentiated the control subjects from each patient group. The left temporal lobe was significantly smaller than the right in control subjects. The epileptics' temporal lobes were smaller on the side of the seizure focus, compared to the temporal lobes in the control subjects. MRI hippocampal measurements were compared to hippocampal neuronal densities obtained postoperatively. Significant correlations were obtained between the ratio (side ipsilateral to focus/side contralateral to focus) of MRI hippocampal measurements and neuronal densities in all hippocampal subfields except CA2. Prior to surgery, patients were administered the Wechsler Memory Scale and the verbal Selective Reminding Test. Significant correlations existed between MRI measurements of the left hippocampus and the Wechsler logical memory percent retention scores and between the left temporal lobe measurements and the verbal Selective Reminding Test scores for patients with seizure foci in the left temporal lobe.

Adolescent↗
PubMed1992

Perivascular innervation is lost in experimental atherosclerosis.

Nerve fibers, immunohistochemically positive for neuropeptide Y, tyrosine hydroxylase, calcitonin gene-related peptide and substance P, form a perivascular network surrounding the carotid arteries of New Zealand White rabbits. Transmission electron microscopy demonstrates that the nerve fibers are primarily located at the adventitial-medial border. Placing a silastic collar around a carotid artery for 14 days, in rabbits fed a diet high in cholesterol, resulted in a focal, intimal thickening in 10 out of 12 rabbits. Contralateral sham-operated arteries showed no intimal thickening. At sites where intimal thickening occurred, there was a disappearance of the perivascular nerve network. The carotid arteries from rabbits that did not respond to the collar and the sham-operated carotid arteries showed an intact and normal perivascular nerve network. In the group of animals which responded to the collar with intimal thickening, there was evidence of a proliferative response proximal to the collar and in this same tissue there was evidence of degeneration of nerve fibers. In conclusion, it has been demonstrated for the first time that, in regions of the carotid artery where intimal thickening occurred, there was an associated degeneration of the perivascular nerve network. The cause of this degeneration and its functional consequences require further investigation.

Animals↗
PubMed1992

Peptidergic nerve involvement in the control of endothelium-dependent vascular relaxation.

The ability of Acetylcholine (ACh) and A23187 to induce endothelium-dependent relaxation was compared in the isolated perfused mesenteric arterial bed of untreated adult rats, adult rats treated neonatally with capsaicin, and adult rats treated as adults with capsaicin. Following neonatal capsaicin treatment, the response to both agents was reduced. Following adult treatment, the response to both agents was reduced seven days following capsaicin treatment. The same results were obtained in the presence of L-arginine or indomethacin. Tissues from all rats responded equally to sodium nitroprusside. Following capsaicin treatment no change in the structural relationship of the arterial intima was detected but no perivascular nerve fibres immunoreactive to substance P (SP) or calcitonin gene-related peptide (CGRP) could be demonstrated. It is suggested that the reduced response to ACh and A23187 does not involve a change in endothelial muscarinic receptors or a structural change in the arterial intima, but is directly related to the absence of immunohistochemically demonstrable CGRP/SP-containing perivascular innervation.

Acetylcholine↗
PubMed1990

Capsaicin-sensitive nerves influence the release of atrial natriuretic factor by atrial stretch in the rat.

Although many factors may modulate the release of atrial natriuretic factor (ANF), the primary mechanism has been demonstrated to be atrial stretch. Recent studies have led to the suggestion that the peptidergic innervation of the heart, through the release of peptides, may be involved in the control of ANF secretion. We have examined the influence of chronic capsaicin treatment on three models of atrial stretch that release ANF. This treatment inhibited ANF released through in vivo blood volume expansion and through balloon inflation in the right atrium of in vitro isolated perfused hearts. Immunohistochemical and electron microscopical analysis confirmed the absence of innervation of the heart by calcitonin gene related peptide and substance P immunoreactive nerve fibres and apparent lack of effect on atrial granules in capsaicin treated rats. We conclude that capsaicin-sensitive cardiac innervation is a component modulating the release of ANF, stimulated by atrial stretch in the rat.

Animals↗
PubMed1990

Interrelationships of heterozygosity, growth rate and heterozygote deficiencies in the coot clam, Mulinia lateralis.

Allozyme surveys of marine invertebrates commonly report heterozygote deficiencies, a correlation between multiple locus heterozygosity and size, or both. Hypotheses advanced to account for these phenomena include inbreeding, null alleles, selection, spatial or temporal Wahlund effects, aneuploidy and molecular imprinting. Previous studies have been unable to clearly distinguish among these alternative hypotheses. This report analyzes a large data set (1906 individuals, 15 allozyme loci) from a single field collection of the coot clam Mulinia lateralis and demonstrates (1) significant heterozygote deficiencies at 13 of 15 loci, (2) a correlation between the magnitude of heterozygote deficiency at a locus and the effect of heterozygosity at that locus on shell length, and (3) a distribution of multilocus heterozygosity which deviates from that predicted by observed single-locus heterozygosities. A critical examination of the abovementioned hypotheses as sources of these findings rules out inbreeding, null alleles, aneuploidy, population mixing and imprinting as sole causes. The pooling of larval subpopulations subjected to varying degrees of selection, aneuploidy or imprinting could account for the patterns observed in this study.

Alleles↗