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Biomedical subjects

R Thorne

Publications and source records attributed to R Thorne.

At least 19 recordsLinked to original sources
PubMed2004

Hand rhythmic tapping and timing in Parkinson's disease.

BACKGROUND: Dysrhythmia is one of the features frequently associated with the motor disturbance in Parkinson's disease (PD). The mechanism responsible for this phenomenon is not known. OBJECTIVES: To assess the rhythmic movements of the hand in PD patients in general and in parkinsonian subtypes. METHODS: Fifty-one PD patients (32 males) with mean age 66.3 +/- 9.1 years (6.6 years of symptoms) and 36 healthy controls (age 64.9 +/- 13.2, range 40-85) were studied. Subjects were asked to tap with their dominant or less affected arm on a digitized switch board at their most comfortable pace (16 s), fastest tapping speed (12 s), and at different frequencies provided by a metronome. The mean rhythm and the tap-to-tap variation were compared. Performance of the PD patients and control subjects were compared, as there were different subtypes of PD patients. Patients were subclassified into: tremor predominant (TP) (14 patients), freezing predominant (FP) (11 patients), akinetic-rigid (AR) (12 patients) and an unclassified group (UC) (14 patients). Results. There was no significance difference between patients and controls in the self-chosen, most comfortable tapping rate or in the tap-to-tap variation of the self-paced task. PD patients tapped at a significantly slower rate than controls when asked to tap at their fastest rate (4.39 +/- 1.32 vs. 5.14 +/- 1.31 Hz; p < 0.01). This difference was the result of an especially slow performance of the TP and AR subgroups (3.85+/-1.20 and 3.88+/-1.46, respectively; p < 0.01 compared to the control group). TP was the only subgroup to show an increased tap-to-tap variation at their fastest tapping rate compared to the control group (0.070 +/- 0.057 vs. 0.029 +/- 0.025 s, respectively, p < 0.05). The TP subgroup also showed hastening when they followed an externally given rhythm of 2.5 Hz and they tapped at 2.73 +/- 0.36 Hz p < 0.05). CONCLUSIONS: Externally driven and self-paced tapping are preserved in patients with PD, when examined at their best 'on' state. The tremor predominant subgroup seems to have specific pacing disturbances.

Adult↗
PubMed2004

Subdivision of essential tremor patients according to physiologic characteristics.

OBJECTIVE: To test the effect of different forearm postures on tremor characteristics. We hypothesized that changes in tremor characteristics in relation to posture can subclassify essential tremor (ET) patients. METHODS: Fourteen ET patients were tested while seated and holding a full cup in three well-defined arm postures: 15 cm above the armrest, elbow at 90 degrees flexion and when the cup was near the mouth. Hand movements were recorded using a triaxial accelerometer. Concomitantly, we recorded surface electromyogram (EMG) signals from the wrist extensor muscles. Hand acceleration and the primary tremor frequency from the power spectrum were calculated for each posture in two independent trials. The coherence at the primary tremor frequency between the EMG and the accelerometry signals was calculated. RESULTS: ET patients could be classified into two groups: ET-1 (nine patients) had position-dependent peak frequencies while ET-2 (five patients) had position-independent peak frequencies. The latter group had significantly higher coherencies between EMG and accelerometry of tremor and insignificantly higher tremor amplitudes compared with ET-1. In both groups tremor amplitude increased when the hand was near the mouth. CONCLUSION: The results suggest that ET patients can be classified based on the position dependence of frequency and other physiologic properties.

Acceleration↗
PubMed2002

Ultra-relativistic electrons in Jupiter's radiation belts.

Ground-based observations have shown that Jupiter is a two-component source of microwave radio emission: thermal atmospheric emission and synchrotron emission from energetic electrons spiralling in Jupiter's magnetic field. Later in situ measurements confirmed the existence of Jupiter's high-energy electron-radiation belts, with evidence for electrons at energies up to 20[?]MeV. Although most radiation belt models predict electrons at higher energies, adiabatic diffusion theory can account only for energies up to around 20[?]MeV. Unambiguous evidence for more energetic electrons is lacking. Here we report observations of 13.8[?]GHz synchrotron emission that confirm the presence of electrons with energies up to 50[?]MeV; the data were collected during the Cassini fly-by of Jupiter. These energetic electrons may be repeatedly accelerated through an interaction with plasma waves, which can transfer energy into the electrons. Preliminary comparison of our data with model results suggests that electrons with energies of less than 20[?]MeV are more numerous than previously believed.

Journal Article↗
PubMed1999

Health status in 52 long-term survivors of pediatric brain tumors.

The percentage of children who survive childhood brain tumors is increasing. A number have neurological and other sequelae which impact on the quality of their survival. We reviewed long-term survivors using a standardized health status instrument. The mothers of 52 survivors of brain tumors were surveyed. Eight different aspects (attributes) of health status were scored. The first 6 of these attributes were scored in a health status index (HSI) developed at McMaster University. Subgroup analysis was performed. Limitation in the quality of life was found in one of the 8 attributes in all but 2 of the subjects. The health status index (HSI) score using the first 6 attributes of this survey had a median of 0.73 (range 0.16-1.00). This score is lower than that found in previously surveyed survivors of leukemia or other childhood cancers. Examination of age at diagnosis, extent of surgery, sex and therapeutic modalities used showed no correlation with HSI score. Those with supratentorial astrocytomas had a lower HSI score (0.65) than those with infratentorial astrocytomas (0.85) (p = 0.05). Children with craniopharyngiomas had a poor score (0.64). This survey shows that the survivors of brain tumors have an appreciable burden of morbidity. Most have deficits in health status that affect many areas of their lives. Apart from site of the primary tumor, there was little correlation between subgroups studied and health status. The health status of children who survive brain tumors is lower than that of survivors of other childhood malignancies.

Adolescent↗
PubMed1997

Role of ganglionic cotransmission in sympathetic control of the isolated bullfrog aorta.

1. The relation between preganglionic activity and arterial tone was studied in preparations of bullfrog lumbar sympathetic ganglia 7-10 and the dorsal aorta. 2. Two or more stimuli evoked contractions when applied to the preganglionic C, but not the B pathway. Contractions were blocked when transmission in ganglia 9 and 10 was disrupted by cutting the sympathetic chain or adding (+)-tubocurarine. Contractions were antagonized by postganglionic action of guanethidine, but not by phentolamine or suramin. 3. Aortic responses to short trains (10-100 stimuli) were half-maximal at 0.3-0.5 Hz, saturated near 1 Hz and had a minimum latency of 8.9 s. By contrast, responses to 300 stimuli were half-maximal at 1 Hz and became 2.5-fold larger at 10 Hz. 4. Exogenous luteinizing hormone releasing hormone (LHRH) potentiated preganglionically evoked contractions. Endogenous LHRH mediated contractions evoked by 10 Hz stimulation in (+)-tubocurarine. These responses had a longer latency than in normal Ringer solution and were blocked by [D-pGlu1, D-Phe2, D-Trp3.6]-LHRH. The LHRH antagonist did not alter contractions evoked by continuous stimulation in normal Ringer solution or by bursts of stimuli in hexamethonium. 5. Exogenous neuropeptide Y (NPY) potentiated neurogenic contractions and responses to adrenaline. Benextramine blocked contractions produced by nerve stimulation, adrenaline and NPY, but not ATP. 6. The results show that contractions of the isolated aorta are tuned to physiological frequencies of activity in sympathetic C neurones. Peptidergic cotransmission in the ganglia can increase arterial tension, but not during synchronous activation of primary nicotinic synapses. It is suggested that the physiological role of LHRH arises from interactions with subthreshold nicotinic EPSPs and that postganglionic release of NPY shifts frequency tuning of the circuit during prolonged activity.

Animals↗
PubMed1996

Cystic angiomatosis: case report and review of the literature.

The objective of this article was to offer a better characterization of the typical clinical presentation, radiologic findings, histology, treatment approaches, and differential diagnosis of cystic angiomatosis, a rare condition of which previous reports have been confusing because of unclear diagnostic criteria, different classifications, and variations in terminology. A case report using the improved imaging techniques of computed tomography scanning is presented in addition to an analysis and review of the previous literature, which relied heavily on plain film radiography, biopsy, and necropsy for diagnosis. A case report of a 26-year-old man initially symptomatic at age 12 is presented. Although a rare condition, cystic angiomatosis must be considered in pediatric and young adult patients presenting with diffuse, multifocal, cystic skeletal lesions, with or without visceral involvement.

Abdomen↗
PubMed1996

Radon in Devon and Cornwall and paediatric malignancies.

Exposure to radon in dwellings may cause cancer including paediatric malignancies. Devon and Cornwall have the highest exposure to radon of the counties of England. However, within these counties there is considerable variation in exposure. Exposure to radon in the 283 postcode sectors of the two counties has been published. The incidence of childhood malignancies between 1976 and 1985 was studied to compare postcode sectors of radon exposures > or = 100 Bq/m3 with sectors < 100 Bq/m3. No significant difference in the incidence rate of 106.7 per million child years in the high radon postcode sectors and 121.7 in the low (P = 0.29) was found. When the incidences of individual tumours were examined, a significantly increased rate of neuroblastoma (P = 0.02) and a non-significant increased rate of acute myeloid leukaemia were found in the high exposure postcode sectors. No association between radon exposure and overall rate of childhood malignancy was found.

Acute Disease↗
PubMed1996

Intracranial ependymomas: analysis of prognostic factors in a population-based series.

A retrospective study of 31 children presenting in the period 1976-1993 with intracranial ependymomas in the south-west region of the UK was performed. The diagnosis was confirmed by histological review and several histological variables recorded, including pleomorphism, cellularity, numbers of mitotic figures and extent of necrosis. Histological features, presentation and treatment were correlated with outcome. Eleven patients had supratentorial primaries and 20 infratentorial primaries. Seven patients had macroscopically complete resections of which 5 had supratentorial primaries. Eight patients had no other therapy apart from surgery. Six patients received craniospinal irradiation, 11 had involved-field irradiation and 14 did not have radical radiotherapy. Twelve patients received chemotherapy. Eleven patients are relapse-free at a median of 43 months. Of the 20 relapses, 19 were local and only 1 metastatic. The grade of the tumor assigned at presentation had no correlation with outcome. On histological review, the only feature that had a significant correlation (p = 0.05) with survival was tumor cellularity. There was a survival advantage for a supratentorial primary site (p = 0.04). The event-free survival was significantly longer for patients diagnosed after 1986 than before (p = 0.006). Survival was not significantly affected by radiotherapy or chemotherapy. Children who had had a macroscopically complete excision of the tumor had a 5-year survival of 69% as opposed to 47% for those who had incomplete surgery, but this difference is not significant (p = 0.13). The data suggest that: (1) the event-free survival rate has improved significantly with time; (2) there is little correlation between a variety of pathological features and outcome, and (3) failure at the primary site is the major obstacle to improved cure rates. The role of complete resection, including second-look surgery, needs further evaluation.

Adolescent↗
PubMed1995

An aortic projection of lumbar paravertebral sympathetic neurons in the bullfrog.

A population of sympathetic neurons which projects from paravertebral ganglia to the dorsal aorta was identified in the bullfrog based on its electrophysiology and anatomy. The aorta is bilaterally supplied by about a dozen connective nerves arising from sympathetic ganglia 7-10. From compound action potentials, the majority of fibers can be identified as postganglionic axons belonging to both the B- and C-cell groups. Tracing experiments indicated that 95 +/- 21 (mean +/- SD) neurons project into each connective and that axons in connectives penetrate the wall of the aorta where they break into small bundles. Staining wholemounts of the aorta for neuropeptide Y revealed a plexus of varicose axons which presumably arise from sympathetic C neurons. These observations imply that the aorta is sympathetically innervated by paravertebral C neurons.

Animals↗
PubMed1994

Childhood malignancies in the south-west region of England, 1976-1985.

The incidence and pattern of childhood cancer in the South-West Region of the United Kingdom was studied in the period 1976-1985 to see if there was any unevenness in distribution. This region consists of five counties with considerable variation in radon exposure and urbanisation. Cases were identified from multiple sources and the basis of the diagnosis reviewed. Internationally accepted diagnostic categories were used. Six hundred seventy-eight cases were found, giving an age standardised incidence rate of 114.2 per million childhood years. The incidence of different cancers by sex was strikingly similar to the Manchester Children's Tumour Registry, from a noncontiguous region, with three exceptions. In the South-West, there was a higher rate of soft tissue sarcoma in boys (P = 0.01) and lower rates of sympathetic nervous system and germ-cell tumours in girls (P = 0.01 and P = 0.04, respectively). There was no significant variation in cancer incidence among the five counties or with time. The incidence rate in counties of high radon exposure was not higher than with low radon exposure. The overall incidence in counties with urban districts was not significantly increased compared to those without, although there was a nonsignificant trend towards a higher incidence of leukaemia (P = 0.08). The incidence and type of childhood cancer are similar to those in a noncontiguous region. Geographical and temporal incidence are remarkably stable. Local environmental variation may not play a major role in the causality of childhood cancer.

Adolescent↗
PubMed1992

Ganglionic and arterial release of neuropeptide Y by bullfrog sympathetic neurons.

Sympathetic C neurons in lumbar paravertebral ganglia of the bullfrog have previously been shown to be vasomotor in function and to express neuropeptide Y (NPY). In the present experiments, a sensitive radioimmunoassay was used to measure the NPY content of ganglia and the descending abdominal aorta and to measure the overflow of NPY evoked by depolarizing concentrations of K+. Paravertebral ganglia 9 and 10 contain 3.1 pg NPY/micrograms protein and the aorta contains 0.18 pg NPY/micrograms protein. During 20-min depolarizations in high K+ (58 mM) Ringer, the ganglia released approximately 5% of their NPY content and the aorta released approximately 2% of its NPY content. Pretreatment of the tissues with Ringer containing 0.18 mM Ca2+, 8 mM Mg2+, and 1 mM Co2+ blocked the NPY release elicited by high K+. These findings provide further evidence that NPY is a postganglionic co-transmitter in sympathetic C neurons of the bullfrog.

Animals↗
PubMed1989

Exercise stress alters the percentage of splenic lymphocyte subsets in response to mitogen but not in response to interleukin-1.

Results of previous work from this laboratory demonstrated that reduced murine splenic lymphocyte proliferation in response to Concanavalin A (Con A) is associated with acute exercise stress. The present study was conducted to determine whether the stress of physical work further affects the expression of splenic lymphocyte phenotypes following in vitro stimulation by the T-cell mitogen, Con A, and also by interleukin-1 (IL1). Mice in this study were assigned to one of five treatment conditions. Two groups of mice were exposed only to the noise and vibration of a treadmill for 8 weeks; one of these groups was given an acute exhaustive run. Three groups of mice were exposed to 8 weeks of treadmill training: one group was sacrificed immediately after training, a second group was sacrificed 72 h after training, and a third group was rested for 72 h and then given an acute exhaustive run. There was a significant effect of stimulation by Con A on the percentage of splenic lymphocytes positive for Thy1.2, Lyt-2, L3T4, and goat anti-mouse Ig, regardless of treatment condition. Acute exercise, however, affected the magnitude of the response. There was a significantly greater increase in the percentage of Thy1.2+ and, especially of, Lyt-2+ cells in stimulated splenic lymphocytes from untrained mice given an exhaustive exercise session compared with controls and with trained mice. There was no significant effect of the addition of IL1 to any culture, irrespective of treatment condition. These results suggest that reduced mitogenesis after acute exercise stress exposure may be related to the increased appearance of Lyt-2+ (T suppressor) cells.

Animals↗
PubMed1989

Exercise stress alters murine lymphocyte subset distribution in spleen, lymph nodes and thymus.

Our previous work indicated that exercise stress in mice was associated with reduced splenic lymphocyte proliferation to T cell mitogens. The purpose of this study was to determine the effect of acute exercise stress and exercise training on the phenotype distribution of murine lymphocytes in the spleen, lymph nodes and thymus. In mice given an exhaustive bout of treadmill exercise, the percentage of Thy 1.2 and Lyt2 antigen bearing cells decreased in the thymus, but the percentage of L3T4-positive cells did not change significantly. Acute exercise did not alter the percentage of Thy1.2, L3T4 or Lyt2-positive cells in the secondary lymphoid compartments (nodes, spleen). By contrast, in mice given a chronic exercise training programme (8 weeks duration; 30 m/min, 8 degrees slope, 30 min/session, 5 daily sessions/week) followed by a 72 h rest period, the percentage of L3T4-positive cells increased by 53% in the spleen, 19% in the lymph nodes and 29% in the thymus compared with sedentary controls; no parallel increase in the percentage of Thy1.2 antigen bearing cells was observed. These results suggest that the effect of exercise on the frequencies of lymphocyte subpopulations in murine lymphoid compartments is dependent upon the chronicity of the stress and probably on the accompanying physiological adaptations to the stress.

Animals↗
PubMed1987

Dietary fiber.

Studies done on dietary fiber (DF) over the past five years are presented in this Review. The involvement of dietary fiber in the control of plasma glucose and lipid levels is now established. Two dietary fiber sources (soybean and fenugreek) were studied in our laboratory and are discussed herein. These sources were found to be potentially beneficial in the reduction of plasma glucose in non-insulin dependent diabetes mellitus subjects. They are shown to be acceptable by human subjects and are easy to use either in a mixture of milk products and in cooking. The mechanism by which dietary fiber alters the nutrient absorption is also discussed. The effect of DF on gastric emptying, transit time, adsorption and glucose transport may contribute to reducing plasma glucose and lipid levels. DF was found to be effective in controlling blood glucose and lipid levels of pregnant diabetic women. Dietary fiber may also be potentially beneficial in the reduction of exogenous insulin requirements in these subjects. However, increased consumption of DF may cause adverse side effects; the binding capabilities of fiber may affect nutrient availability, particularly that of minerals and prolonged and high DF dosage supplementation must be regarded cautiously. This is particularly true when recommending such a diet for pregnant or lactating women, children or subjects with nutritional disorders. Physiological effects of DF appear to depend heavily on the source and composition of fiber. Using a combination of DF from a variety of sources may reduce the actual mass of fiber required to obtain the desired metabolic effects and will result in a more palatable diet. Previously observed problems, such as excess flatus, diarrhea and mineral malabsorption would also be minimized.

Blood Glucose↗