Biomedical subjects

K Dickson

Publications and source records attributed to K Dickson.

At least 19 recordsLinked to original sources

PubMed2005

Self-reported anti-social behaviour: prevalence and risk factors amongst adolescents with and without intellectual disability.

BACKGROUND: Research has suggested increased risk of anti-social behaviour amongst individuals with intellectual disability (ID). METHODS: This study reports the results of a secondary analysis of data relating to self-reported anti-social behaviour, obtained from the 1999 Office for National Statistics (ONS) study of the mental health of children and adolescents in Great Britain. Self-report data from 4174 adolescents was available. Within this group, a sub-group of 98 adolescents with ID was identified. Data covered a variety of sub-types of anti-social behaviour. RESULTS: Comparisons of individuals with ID and those without ID indicated a significantly higher prevalence of a number of types of self-reported anti-social behaviour in the ID sample. Further analyses indicated however, that these between group differences were accounted for by the higher rates of social deprivation and child mental health problems among the ID sample. CONCLUSIONS: Rather than ID per se being associated with increased rates of anti-social behaviour, adolescents with ID may be more likely to experience risk factors (lower socio-economic status and mental health problems) known to be associated with anti-social behaviour. The clinical implications of this and possible future directions for research are discussed.

Adolescent↗

PubMed2003

Comparative studies of high performance swimming in sharks II. Metabolic biochemistry of locomotor and myocardial muscle in endothermic and ectothermic sharks.

Metabolic enzyme activities in red (RM) and white (WM) myotomal muscle and in the heart ventricle (HV) were compared in two lamnid sharks (shortfin mako and salmon shark), the common thresher shark and several other actively swimming shark species. The metabolic enzymes measured were citrate synthase (CS), an index of aerobic capacity, and lactate dehydrogenase (LDH), an index of anaerobic capacity. WM creatine phosphokinase (CPK) activity, an index of rapid ATP production during burst swimming, was also quantified. Enzyme activities in RM, WM and HV were similar in the two lamnid species. Interspecific comparisons of enzyme activities at a common reference temperature (20 degrees C) show no significant differences in RM CS activity but higher CS activity in the WM and HV of the lamnid sharks compared with the other species. For the other enzymes, activities in lamnids overlapped with those of other shark species. Comparison of the HV spongy and compact myocardial layers in mako, salmon and thresher sharks reveals a significantly greater spongy CS activity in all three species but no differences in LDH activity. Adjustment of enzyme activities to in vivo RM and WM temperatures in the endothermic lamnids elevates CS and LDH in both tissues relative to the ectothermic sharks. Thus, through its enhancement of both RM and WM enzyme activity, endothermy may be an important determinant of energy supply for sustained and burst swimming in the lamnids. Although lamnid WM is differentially warmed as a result of RM endothermy, regional differences in WM CS and LDH activities and thermal sensitivities (Q(10) values) were not found. The general pattern of the endothermic myotomal and ectothermic HV muscle metabolic enzyme activities in the endothermic lamnids relative to other active, ectothermic sharks parallels the general pattern demonstrated for the endothermic tunas relative to their ectothermic sister species. However, the activities of all enzymes measured are lower in lamnids than in tunas. Relative to lamnids, the presence of lower WM enzyme activities in the thresher shark (which is in the same order as the lamnids, has an RM morphology similar to that of the mako and salmon sharks and may be endothermic) suggests that other factors, such as behavior and swimming pattern, also affect shark myotomal organization and metabolic function.

Adaptation, Biological↗

PubMed2001

Outpatient management of low-velocity gunshot-induced fractures.

This prospective study evaluated the efficacy of an outpatient management protocol for patients with a gunshot-induced fracture with a stable, nonoperative configuration. Forty-one patients (44 fractures) with a grade I or II open, nonoperative fracture secondary to a low-velocity missile comprised the study population. Patients were treated by a standard protocol, which included 1 g of cefazolin administered in the emergency room and a 7-day course of oral cephalexin. Follow-up visits were performed until complete wound and fracture healing were achieved. Thirty-two (78%) of 41 patients underwent full follow-up. Average follow-up was 5.2 months. One (2.8%) fracture (distal fibula) developed a superficial infection, which responded to an additional week of oral antibiotics, and no patient developed a deep infection. There was 1 delayed union and 2 patients with painful retained shrapnel. These results demonstrate that patients with stable, low-velocity, gunshot-induced fractures can be managed effectively and safely on an outpatient basis using this protocol.

Adult↗

PubMed2000

Axonal sprouting following lesions of the rat substantia nigra.

Parkinson's disease is characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Symptoms do not appear until most nigral neurons are lost, implying that compensatory mechanisms are present. Sprouting has been proposed as one of these mechanisms. This study quantified the extent of compensatory axonal sprouting following injury of dopaminergic neurons within the substantia nigra pars compacta. Specifically, the extent of the axonal arbour and axonal varicosity morphology was measured after partial destruction (with 6-hydroxydopamine) of the substantia nigra of the adult male rat. Four months later, the substantia nigra was injected with the anterograde neuronal tracer dextran-biotin to trace the full extent of individual axons. An unbiased estimate of neuron number was performed in each animal. This demonstrated nigral neuronal loss ranging from 10 to 90% on the side that received the injection whilst a 7% reduction was observed in the side contralateral to the lesion. Coincident with this loss, some nigral neurons lose tyrosine hydroxylase expression. Vigorous axonal sprouting was observed in the terminal arbours of lesioned animals and was associated with an increased axonal varicosity size. Axonal varicosities and branching points were primarily confined to the dorsal 1.5mm of the caudate-putamen, an area predominantly innervated by nigral neurons. It appears that dopaminergic neurons were responsible for this sprouting because the density of dopamine transporter immunoreactive varicosities in the caudate-putamen was maintained until about a 70% loss of neurons. It was concluded that substantial compensation in the form of sprouting and new dopaminergic synapse formation occurs following lesions of the substantia nigra pars compacta.

Adrenergic Agents↗

PubMed1999

The anatomy and cell biology of peripheral myelin protein-22.

The gain of function phenotypes exhibited by the heterozygous Tr, Tr-J, and CMT1A mutations indicate that these mutations interfere with more than the function of a single PMP22 allele. The identification of proteins that interact with PMP22 and that are sensitive both to stoichiometry and the effects of the mutations could provide important leads to a unified hypothesis to explain the riddle of the PMP22-related neuropathies.

Animals↗

PubMed1998

Physiological evidence for arteriovenous anastomoses in the uterine circulation of late-pregnant ewes.

1. The objective of the present study was to determine whether arteriovenous anastomoses (AVA) are present in the uterine circulation of conscious, late-pregnant ewes. 2. Twenty late-pregnant ewes were assigned to two groups. In group 1, 15 microm coloured microspheres were injected into the uterine artery of the pregnant horn and the relative proportion of microspheres trapped in the uterus and lungs was determined. The percentage shunting of blood measured by this method was 17+/-3%, representing a blood flow of 164+/-39 mL/min (n = 12). Any contribution of ovarian, cervical, rectal and other vascular beds was specifically excluded in this group. 3. In group 2, total uterine capillary flow was measured using the reference blood flow method, by injecting 15 microm microspheres into the heart. Calibrated flow probes, placed on both main uterine arteries, concurrently measured total uterine blood flow. Total blood flow to the uterus (flow probe) was significantly greater (t = 3.415; P = 0.027) than uterine capillary flow (microspheres), indicating AVA shunting in the uterine circulation. Mean total blood flow to the uterus was 1749+/-160 mL/min, of which an average 25+/-5% (n = 5 sheep) was shunted. 4. The percentage AVA shunting for groups 1 and 2 was not significantly different (t = 1.219; P = 0.24) and, when combined, the mean percentage of uterine blood flow passing through AVA in the late-pregnant sheep was determined to be 19+/-3%. 5. The present study shows that AVA are present and patent in the uterine circulation of late-pregnant ewes and that they account for the shunting of approximately 20% of the uterine blood flow into the maternal venous circulation.

Animals↗

PubMed1997

Unrecognized pregnancy in the overdosed or poisoned patient.

A 22-year-old woman was found in bed unresponsive and hypotensive after an apparent overdose. Subsequent workup in the emergency department identified a ruptured ectopic pregnancy and extensive hemoperitoneum. A significant delay occurred when emergency physicians excluded the possibility of pregnancy because of the patient's normal menstrual history. A qualitative serum or urine pregnancy test is recommended in all women of child-bearing age who present with poisoning or drug overdose.

Adult↗

PubMed1997

[The United Nations confronts the challenges of a changing world: the 49th Annual DPI/NGO Conference].

The United Nations (UN), previously considered a forum exclusively for sovereign governments, has changed over time in tune with various political, economic, social, and cultural phenomena. One of these is the growing presence of nongovernmental organizations (NGOs) in international agencies and activities. The 49th Annual Conference of the Department of Public Information and NGOs, held at UN headquarters on 10 September 1996, analyzed the extent to which the UN is allowing NGOs to participate in its discussions of policy, institutional reform, and field operations. The issues discussed at the Conference and the challenges that face the UN in a changing world from the subject of this report.

Health Care Reform↗

PubMed1997

[Collaboration between non-governmental organizations and governments for health sector reform].

One of the most prominent current trends is the vital and increasingly visible role played by nongovernmental organizations (NGOs) in the world in general and in the activities and conferences sponsored by the United Nations (UN). Given these circumstances, part of the mission of PAHO is to strengthen the ties between governments and NGOs through provision of technical cooperation and support in priority program areas, such as health care, and facilitation of the exchange of information and experiences. This report examines different lines of action designed to improve collaboration between NGOs and governments in the area of health sector reform.

Government Agencies↗

PubMed1996

Astrocyte reactivity in neonatal mice: apparent dependence on the presence of reactive microglia/macrophages.

In neonatal mice, an acute injury produced by a stab wound to the cortex results in minimal astrocyte reactivity, as has been observed by others. However, if the source of the stab wound, a piece of nitrocellulose (NC) membrane, were now implanted in the cortex for a period of time (chronic NC implant injury), then extensive astroglial reactivity in the neonatal brain ensues. The astrogliosis is manifested by increased mRNA, protein content, and immunoreactivity for GFAP, and by ultrastructural changes. Given the previous reports that inflammatory cytokines are possible mediators of astrocyte reactivity (e.g., Balasingam et al: J Neurosci 14:846, 1994), we examined the brain parenchyma of neonatal mice following an NC stab or implant injury, with minimal or extensive astrogliosis, respectively, for a possible differential representation of inflammatory cells. A significant correlation (r = 0.87, P < 0.05) was observed between the occurrence of astrogliosis and the presence of reactive microglia/macrophages; no other inflammatory cell type was detected in the brain parenchyma of neonatal mice following NC implant injury. We suggest that reactive microglia/macrophages are required for the evolution of cells into reactive astrocytes following insults to the neonatal brain.

Aging↗

PubMed1996

Outcome of rotationally unstable pelvic ring injuries treated operatively.

Twenty-nine patients with unstable rotational injuries treated operatively were observed for an average of 39 months. There were 24 associated orthopaedic injuries. Twenty-seven patients had symphysis disruption (4 with rami fractures) and 2 had rami fractures associated with an acetabular fracture. Followup evaluation of those who could be evaluated in each category revealed that 96% had no pain or pain only on strenuous activity, ambulated without assistance or limitations, and returned to work. Open reduction and internal fixation of rotationally unstable pelvic fractures results in a high functional success rate.

Adolescent↗

PubMed1995

Discriminative power of visual evoked potential characteristics in multiple sclerosis.

To investigate the discriminative power of pattern-reversal visual evoked potential characteristics (peak latencies and amplitude) and to test whether the addition of visual evoked potential amplitude can increase the power of the visual evoked potential in the diagnosis of multiple sclerosis, we retrospectively studied visual evoked potentials in 59 patients with definite multiple sclerosis and 126 control subjects. Two check sizes (17' and 10') were used. Females had significantly higher amplitudes and shorter latencies than males. N80 latency showed a gradual increase and P100 amplitude a decrease with age. P100 latency was stable between the ages of 20 and 55 years but was increased in childhood and the elderly. The significance of visual evoked potential peak latencies and amplitude in separating the two groups was investigated by means of a (multivariate) discriminant analysis. The visual evoked potential with a pattern of 10' could be measured in 58% of patients with multiple sclerosis. The exclusive use of the P100 amplitude in the discriminant analysis resulted in a percentage of correctly classified cases of 84%, whereas for P100 and N80 latency it was 85% and 90%, respectively. With the 17' pattern, the N80 latency yielded also a higher correct percentage than did the P100 latency. Although N80 latency is, to a greater extent than P100 latency, influenced by age, sex and size of stimulus pattern, when these influences are accounted for, the N80 latency is a more sensitive measure than P100 latency in the classification of multiple sclerosis. Combined use of latency and amplitude for discriminant analysis yielded no significant improvement of the percentage of correctly classified cases.

Adolescent↗

PubMed1995

Humeral avulsion of glenohumeral ligaments as a cause of anterior shoulder instability.

The avulsion of the glenohumeral ligament labral complex at the glenoid (Bankart lesion), as well as ligamentous laxity are well known causes of anterior shoulder instability. A lesser known entity, the humeral avulsion of glenohumeral ligaments (HAGL), was studied to determine its incidence and its role in anterior glenohumeral instability. Sixty-four shoulders with the diagnosis of anterior instability were prospectively evaluated by arthroscopy for intraarticular pathology, including Bankart, capsular laxity, and HAGL lesions. Six shoulders were found to have HAGL lesions (9.3%), 11 shoulders with generalized capsular laxity (17.2%), and 47 shoulders with Bankart lesions (73.5%). In patients with documented anterior instability without a demonstratable "primary" Bankart lesion, a HAGL lesion should be ruled out. This lesion is readily recognized arthroscopically, and an appropriate repair of this lesion can restore anterior stability to the patient. The pathological anatomy of the HAGL lesion and our treatment of this lesion is discussed.

Adolescent↗

PubMed1995

Specific binding of endocrine transforming growth factor-beta 1 to vascular endothelium.

The presentation of recombinant biologically active 125I-TGF-beta 1 via the bloodstream to potential target cells in mice and rats was evaluated by quantitative light and electron microscope radioautography. Specificity was evaluated by in vivo competition with excess unlabeled TGF-beta 1, and integrity of the ligand at the binding site was demonstrated by trichloroacetic acid precipitation after extraction from tissues. The distribution of radiolabel at 2.5, 15, 30, 45, and 60 min after 125I-TGF-beta 1 injection revealed radiolabel principally over microvasculature endothelium but at times > 2.5 min over endothelial endocytic components indicative of internalization. Nonspecific binding of 125I-TGF-beta 1 to the apex of the proximal convoluted tubule of the kidney indicated it as the likely site of rapid clearance of TGF-beta 1 from the circulation, while a comparison of the binding of 125I-TGF-beta 1 (endothelial) to that of 125I-TGF-beta 1 complexed with alpha 2-macroglobulin-methylamine (liver parenchyma) indicated that clearance of TGF-beta 1 complexed alpha 2-macroglobulin was likely via the hepatic alpha 2-macroglobulin receptor. The endothelial TGF-beta receptors uncovered here are likely involved in the local regulatory mechanism of leukocyte and monocyte adhesion and tissue infiltration regulated by endocrine TGF-beta 1.

Animals↗

PubMed1994

TUNAS AS SMALL AS 207 mm FORK LENGTH CAN ELEVATE MUSCLE TEMPERATURES SIGNIFICANTLY ABOVE AMBIENT WATER TEMPERATURE

Tunas (family Scombridae) maintain muscle temperatures (Tm) elevated significantly above ambient water temperature (Ta) by using vascular counter-current heat exchangers (retia mirabilia) to conserve metabolic heat generated by continuous contraction of red muscle fibers. Previous work has documented endothermy and both behavioral and physiological thermoregulation in tunas, but only individuals greater than approximately 1 kg body mass had been studied. The purpose of this study was to measure Tm and to examine heat exchanger morphology in smaller fish in order to determine the minimum size at which tunas can elevate Tm significantly above Ta. Measurements of Tm made immediately after capture in field-caught and laboratory-raised tunas (Euthynnus lineatus, Auxis thazard, A. rochei and Thunnus albacares) spanning a size range of 15.5667 mm fork length (FL) show that tunas 207 mm FL (162.3 g) and larger can elevate red muscle temperature by at least 3.0°C above Ta. E. lineatus, A. thazard and A. rochei of this size possess blood vessels serving the red muscle that are arranged as both lateral and central heat exchangers; the smallest tuna with evidence of a rete was a 108.5 mm FL E. lineatus. In the ectothermic scombrid Scomberomorus sierra (108.7132.0 mm FL), Tm was elevated 0.20.5°C above Ta, and the greatest Tm elevation reported in any ectothermic species is only 2.7°C. Taken together, these data provide evidence that tunas greater than 207 mm FL are endothermic.

Journal Article↗

PubMed1994

Delayed unions and nonunions of open tibial fractures. Correlation with arteriography results.

To investigate the importance of arterial integrity in tibial fracture healing, the authors retrospectively assessed prognosis as a function of arterial injury in a large series of tibial fracture patients. The records of 114 patients who were treated for an open fracture of the tibia at a San Francisco hospital between 1981 and 1991 were selected for review; in each case, the injury had been caused by a blunt trauma, and arteriography had been performed to evaluate a suspected arterial injury in the ipsilateral extremity. Sixty-two patients had had a normal arteriogram and 52 had demonstrated occlusion of one or two of the three arteries that supply the foot. The group of patients who had demonstrated arterial occlusion had a significantly greater incidence of delayed union or nonunion (24 of 52 compared with ten of 62) and notably more cases of osteomyelitis (nine of 52 compared with four of 62); when the patients with osteomyelitis are excluded, the difference between the groups is still significant. This study is the first that indicates that patients with open fractures of the tibia who demonstrate arterial occlusion in their ipsilateral extremity may be more prone to delayed union or nonunion. More vigilant follow-up evaluation may therefore be warranted in such patients to better anticipate the need for exchange rodding or bone grafting.

Adolescent↗

PubMed1993

Close encounters: an examination of UFO experiences.

Ss who reported UFO experiences were divided into those whose experiences were nonintense (e.g., seeing lights and shapes in the sky) and those whose experiences were intense (e.g., seeing and communicating with aliens or missing time). On a battery of objective tests Ss in these 2 groups did not score as more psychopathological, less intelligent, or more fantasy prone and hypnotizable than a community comparison group or a student comparison group. However, Ss in the UFO groups believed more strongly in space alien visitation than did comparison Ss. The UFO experiences of Ss in the intense group were more frequently sleep-related than the experiences of Ss in the nonintense group. Among the combined UFO Ss, intensity of UFO experiences correlated significantly with inventories that assessed proneness toward fantasy and unusual sensory experiences. Implications are discussed.

Adult↗

PubMed1993

Use of a Herbert screw for interphalangeal joint arthrodesis.

Fifty-one Herbert-screw fixation procedures were performed for interphalangeal fusion in the hand. The preoperative diagnoses included rheumatoid arthritis, degenerative arthritis, posttraumatic arthritis, and chronic mallet finger. All patients were observed until there was clinical and radiographic evidence of union. Solid osseous union occurred in all patients. Herbert screw fixation for interphalangeal arthrodesis was a simple, effective technique permitting early mobilization; complications were minimal.

Adolescent↗