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Biomedical subjects

J D Hunter

Publications and source records attributed to J D Hunter.

At least 19 recordsLinked to original sources
PubMed1998

The ultrasound diagnosis of posterior shoulder dislocation associated with Erb's palsy.

A case is presented of an infant with Erb's palsy whose posterior dislocation of the humeral head was identified using high-resolution ultrasound following non-diagnostic plain radiographs. Posterior dislocation is associated with Erb's palsy but the diagnosis can be delayed. We suggest the early use of ultrasound in patients with Erb's palsy, as this technique is a safe, quick and reliable method of excluding posterior dislocation.

Birth Injuries↗
PubMed1998

Cortical activation states in sleep and anesthesia. I: Cardio-respiratory effects.

Under light urethane anesthesia, animals cycle through patterns of EEG activity which superficially appear like waking, light sleep and slow-wave sleep patterns (States I, II and III, respectively) in unanesthetized animals. The present study questioned whether similar cortical activity patterns in anesthetized and unanesthetized golden mantled ground squirrels represented analogous states in terms of cardiorespiratory function. Sleep exerted a strong negative influence on breathing frequency and ventilation, but had less consistent effects on tidal volume. Urethane-anesthetized animals demonstrated exactly the same alterations in respiratory variables when switching between states with similar cortical activity. Cardiovascular function was also affected by arousal state; heart rate decreased and variation increased significantly as animals moved from wake into sleep. Although urethane anesthesia greatly increased heart rate and abolished respiratory sinus arrhythmia, state-dependent changes in heart rate were still evident. Overall, the states observed under urethane anesthesia mimicked sleep/wake in terms of their effect on cardio-respiratory function.

Anesthetics, Intravenous↗
PubMed1998

Cortical activation states in sleep and anesthesia. II: respiratory reflexes.

Under urethane anesthesia, animals exhibit patterns of cortical activity similar to those seen in wake, drowsiness and slow-wave sleep in unanesthetized animals. In the present study, hypoxic and hypercapnic ventilatory reflexes were examined in unanesthetized and urethane-anesthetized golden mantled ground squirrels in states with similar EEG profiles. Synchronized EEG patterns occurred less frequently in both unanesthetized and anesthetized animals during hypoxic (10% O2) and hypercapnic (5% CO2) exposure. Breathing frequency fell significantly during sleep in animals breathing all gas mixtures, while the relative ventilatory sensitivity to hypoxia and hypercapnia increased during sleep. Urethane-anesthetized animals also showed significant falls in breathing frequency and ventilation and increases in relative ventilatory sensitivity to hypoxia and hypercapnia as they moved into states with synchronized EEG patterns. These data suggest that the brain activity states observed under urethane anesthesia mimic sleep/wake in terms of their effect on respiratory function and that changes in breathing pattern and the enhancement of ventilatory responses in states with a synchronized EEG is not due solely to changes in levels of behavioural stimuli.

Anesthetics, Intravenous↗
PubMed1998

Resonance effect for neural spike time reliability.

The spike timing reliability of Aplysia motoneurons stimulated by repeated presentation of periodic or aperiodic input currents is investigated. Two properties of the input are varied, the frequency content and the relative amplitude of the fluctuations to the mean (expressed as the coefficient of variation: CV). It is shown that, for small relative amplitude fluctuations (CV approximately 0.05-0.15), the reliability of spike timing is enhanced if the input contains a resonant frequency equal to the firing rate of the neuron in response to the DC component of the input. This resonance-related enhancement in reliability decreases as the relative amplitude of the fluctuations increases (CV-->1). Similar results were obtained for a leaky integrate-and-fire neuronal model, suggesting that these effects are a general property of encoders that combine a threshold with a leaky integrator. These observations suggest that, when the magnitude of input fluctuations is small, changes in the power spectrum of the current fluctuations or in the spike discharge rate can have a pronounced effect on the ability of the neuron to encode a time-varying input with reliably timed spikes.

Action Potentials↗
PubMed1998

Minor morbidity after day-case surgery.

The number of patients and procedures considered suitable for day-case anaesthesia and surgery continues to grow and it is hoped that 50-60% of all operations in the UK will eventually be performed on a day-patient basis. However, minor but troublesome post-operative side effects remain common. We have examined the incidence of the most common causes of minor morbidity, namely headache, nausea/vomiting and pain occurring after a wide variety of day-case surgical and diagnostic procedures. Patient satisfaction with treatment and the impact of day case surgery on the workload of the general practitioner was also assessed. The anaesthetic records of the patients involved were reviewed in an attempt to determine if there was any association between the anaesthetic technique and an adverse outcome. A simple postal questionnaire completed on the morning after surgery was returned by 553 patients (response rate over 87%). More than 50% of respondents complained of some morbidity, with 40% complaining of pain, 19% of headache and 9% of nausea and vomiting. One third self-medicated to modify their symptoms, and in most cases (81%) this was effective. However, 6% of patients called their GP for advice and 2% received a home visit. No patient required readmission. A total of 92 patients (17%) would have preferred treatment as an in-patient. Analysis of the anaesthetic drugs and techniques suggested that the commonly used anti-emetics droperidol and metoclopramide had little effect on the incidence of postoperative nausea and vomiting. Intubation was associated with a significantly higher incidence of minor morbidity although this may be related to surgical factors.

Adolescent↗
PubMed1998

Anaesthetic management of the morbidly obese patient.

Morbidly obese patients are prone to many clinical conditions that can effect anaesthesia. Of major concern to the anaesthetist are difficulties with airway management and abnormalities of cardiorespiratory function. Safe anaesthesia requires an appreciation of potential problems and a thorough understanding of the pathophysiological changes that accompany morbid obesity.

Anesthesia↗
PubMed1997

A survey of homeobox genes in Chaetopterus variopedatus and analysis of polychaete homeodomains.

A survey of genomic DNA from the polychaete Chaetopterus variopedatus was conducted using the polymerase chain reaction. Twelve unique homeobox-containing gene fragments were recovered. Phylogenetic analysis indicates that seven of the fragments are from genes belonging to Hox homeobox classes. Other fragments show orthology with Xlox, caudal, and Prh homeobox classes, with two fragments not definitely assignable to a homeobox class by our analysis. Orthology with gene sequences reported for the polychaete Ctenodrilus serratus, by Dick and Buss (1994), was calculated and indicated that at least eight of the C. variopedatus fragments are homologous to these previously reported sequences. Tabulation of the Hox gene relationships suggest that polychaetes have representative genes of each of the Hox cognate groups except Abd-B. This conclusion further suggests that the Hox cluster in the basal protostome ancestor had already undergone the gene duplications leading to the complete complement of homeotic genes known in Drosophila, with the possible loss of Abd-B in the polychaete lineage.

Amino Acid Sequence↗
PubMed1996

Magnetic resonance imaging in macromelia and macrodactyly.

We report five cases presenting with soft tissue and bone overgrowth that demonstrate the ability of MRI to establish a diagnosis in the absence of specific clinical features. Disorders included macrodystrophia lipomatosa, angiolipomatosis, Klippel-Trenaunay-Weber syndrome, blue rubber bleb naevus syndrome and one case of segmental limited hypertrophy. The MRI appearances, and other radiological features of these conditions are discussed. MRI is recommended in all cases of macrodystrophy when the clinical features and plain film findings are indeterminate.

Adult↗
PubMed1995

Hepatic venous Doppler waveforms: changes in pregnancy.

A total of 75 fasted healthy normal volunteers were examined during various stages of pregnancy. Examinations were performed in a supine position using an Acuson 128 ultrasound scanner with a 3.5 MHz transducer. Doppler interrogation of the middle hepatic vein was made during quiet respiration by one of three examiners. The Doppler waveforms were subsequently assessed blindly by one of the authors and categorized as normal, damped, or flat. Between 12 and 20 weeks, the majority of patients had normal hepatic pulsatility (64%) with 20% damped and 16% flat. Between 20 and 30 weeks there was a significant change (p > 0.001) with 68% being flat, 20% damped, and only 12% normal. In the last 10 weeks of pregnancy the changes were more marked: 80% were flat, 12% dampened, and 8% normal. There was a profound change in hepatic venous pulsatility during pregnancy. Hepatic waveforms changed from their normal pulsatile nature to become completely flat with increasing gestation. These changes were more frequent and more marked the further gestation progressed.

Adult↗
PubMed1995

The radiological appearances of small cell (oat cell) carcinoma of the oesophagus.

We present three patients with primary small cell (oat cell) carcinoma of the oesophagus from a clinical and radiological point of view and review the radiological appearances of previously reported cases. The features of this rate neoplasm are variable, but extensive circumferential oesophageal wall thickening associated with luminal widening should raise the possibility of this diagnosis.

Aged↗
PubMed1995

Spinal cord injury in youth.

To identify special characteristics of the pediatric spinal cord-injured (SCI) population, we analyzed a database of 1,770 traumatic SCI patients; 88 (5%) fell into the two pediatric subgroups: 0-12 years (n = 26) and 13-15 years (n = 62) at time of injury. Differences between age groups were identified with regard to demographics, neurologic characteristics, associated injuries and complications, and management. Mode level of bony injury was C2 in preteens, C4 in teens, and C4-C5 in adults. Scoliosis developed far more frequently in children, particularly preteens (23%), than in adults (5%). Violent etiologies, predominantly gunshots, accounted for a disproportionate share of injuries to preteens (19%) and African-Americans (28%), as compared with adults (12%) and Caucasians (7%). This last finding underscores the urgent need to mount a response to the nationwide proliferation of gunshot-related SCI in children and minorities.

Adolescent↗
PubMed1994

The diagnosis of fatal gas embolism: detection by plain film radiography.

Two recent deaths from massive air embolism occurring while scuba diving off the South coast of Britain are reported. In each case the circumstances of death were uncertain. In both instances the cause of death, that is massive gas embolism, was determined by plain radiography and findings were confirmed at post-mortem. These cases illustrate that in unexplained deaths that occur after exposure to, or change in hyper- or hypobaric conditions, investigation should include pain radiographs of the chest, abdomen and skull.

Adolescent↗
PubMed1991

Circadian variation in alloxan sensitivity of mice as indicated by mortality and blood glucose alteration.

The objective of this study was to determine in mice if a time-dependent pancreatic beta-cell susceptibility to alloxan could be correlated to daily changes in blood glucose levels and to monitor the pattern of blood glucose at various times of day as mice became diabetic. Food was removed from mice standardized to a 12-h light:dark cycle (lights on at 0600 h CST, during the month of June) at 12 h before subcutaneous injection with 0.27 mg/g of alloxan. Six groups of 30 fasted mice were injected at 4-h intervals. Blood glucose levels were measured from each group immediately prior to injection, and at 2, 4, 8, 12, 24, 48, and 216 h after treatment. Animals receiving alloxan during the early- to middark period had an increase in blood glucose after 2 h, followed by a decline to hypoglycemic levels between 4 and 8 h, and recovery to hyperglycemic levels 48 h after alloxan exposure. Three and 30% of these animals were dead at 8 and 48 h, respectively. Mice treated during the midlight span had decreased blood glucose levels 2 h after alloxan treatment followed by an increase to diabetic hyperglycemia within 48 h. Twenty-three and 70% of the animals treated at 1430 h were dead at 8 and 48 h, respectively. At 216 h, total mortality was 45.6% and 81 of the 98 surviving mice were hyperglycemic. These data suggest a greater sensitivity to alloxan during the midlight resting period of the mice. This may be the result of increased sensitivity to the insulin released from the beta cells when alloxan was given during the light span.

Alloxan↗