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Biomedical subjects

J D Miller

Publications and source records attributed to J D Miller.

At least 307 records · Page 17Linked to original sources
PubMed1987

Fat embolism: a clinical diagnosis.

Fat embolism causes a distinctive clinical syndrome usually seen in trauma victims with long bone fractures. Clinical findings include hyperthermia, respiratory distress, petechiae and retinal fat emboli. Neurologic changes include decreased sensorium, decerebrate posturing and seizure activity. Chest radiographs commonly demonstrate bilateral fluffy infiltrates. Laboratory abnormalities include hypoxemia, respiratory alkalosis, anemia and hypocalcemia. Treatment consists of general supportive care with vigorous pulmonary therapy. Most patients have a good recovery.

Adolescent↗
PubMed1986

Minor, moderate and severe head injury.

The future role of the neurosurgeon in the management of head injury is reviewed in terms of the care of patients with minor, moderate and severe head injuries. In minor head injury it is predicted that there will be increasing pressure on the neurosurgeon to undertake the management and follow-up of all patients who have sustained head injury, and this will place a considerable additional load on each neurosurgical unit. This is based on a survey of 1919 head injuries admitted in one calendar year (1981), consisting of 93 severe injuries (GCS less than 8), 210 moderate injuries (GCS 8-12), and 1616 minor injuries (GCS 13/14). In moderate injuries CT will assume a major role in detecting hematoma early and identifying contusions. There may yet be a role for steroids in these cases and there should be a greater use of neurorehabilitation, instead of the current overemphasis on the severely injured. In severe injury future efforts will be to prevent early secondary insults and to find better methods of controlling raised intracranial pressure.

Brain Damage, Chronic↗
PubMed1986

The causes and consequences of minor head injury in the elderly.

The majority of patients admitted to hospital after head injury are young men and the characteristics of this group tend to dominate accounts of cranial injury. All patients of 65 years or more admitted to the Edinburgh Royal Infirmary neurotrauma unit over a 1-year period were studied and 146 suffering minor head injury were identified. In this group the sex incidence was equal and falls were responsible for two-thirds of the injuries. Alcohol was a contributory factor in over half of the male patients. The incidence of other noteworthy medical and social factors was high and the length of stay in hospital was twice that of younger persons. It is suggested that the elderly represent a group with special needs which might most effectively be met by an overnight observation ward served by neurosurgeons and specialists in geriatric medicine.

Accidents, Home↗
PubMed1986

The protein metabolic response to short-term starvation in man.

Plasma protein concentrations, in particular the serum albumin concentration, are often quoted as indicators of nutritional state in surgical patients. Injury also affects the circulating concentrations of these proteins. Twenty students were subjected to a 3-day total fast and the concentration of plasma proteins, generally affected by trauma, determined before and after the fast. The only protein to show any negative response was retinal binding protein which fell by 16% during the starvation period (p < 0.001). Albumin, the protein often used as a nutritional index, demonstrated a significant (p < 0.001) increase during this period. This was not related to changes in the hydration state of the subjects.

Journal Article↗
PubMed1986

Tissue distribution and excretion of radioactivity following administration of 14C-labeled deoxynivalenol to White Leghorn hens.

The disposition of [14C]deoxynivalenol ([14C]DON) administered to hens as either a single oral dose or consumed in spiked feed over a 6-day period was determined by tracing the specific radioactivity of tissues and excreta. Following a single intubated dose (2.2 mg [14C]DON; 2.4 microCi/bird), the toxin was found to be poorly absorbed; peak plasma levels (2-2.5 hr post-treatment) accounted for less than 1% of the administered dose. Maximum tissue residues were measured at 3 hr in all tissues (liver, kidney, brain, heart, spleen, proventriculus, gizzard, small intestine) except for fat, muscle, and oviduct which occurred at 6 hr postdosing. Among the organs, the highest activities were measured in kidney, liver, and spleen; however, these levels were equal to less than 500 ng DON equivalents/g tissue, and declined quickly. Clearance of radioactivity from tissue had an average half-life of 16.83 +/- 8.2 hr (range 7.7-33.3 hr, depending on the tissue). Elimination of the labeled toxin in excreta occurred rapidly; recovery of radioactivity accounted for 78.6, 92.1, and 98.5% of the dose by 24, 48, and 72 hr, respectively. In continuously dosed birds fed 2.2 mg unlabeled DON for 6 days followed by 2.2 mg (1.5 microCi) [14C]DON for 6 days, accumulation of radioactivity in tissues did not occur. Maximum residual levels, which occurred in the kidneys, were only 60 ng DON equivalents/g. Estimated level of residues contained in the edible tissues amounted to only 13-16 micrograms DON/1.5 kg hen.

Animals↗
PubMed1986

Activation of specific central dopamine pathways: locomotion and footshock.

The present study examined whether neostriatal monoamine biochemistry was activated in a bilaterally symmetrical fashion during a non-lateralized forward locomotor task, and whether specific midbrain dopamine (DA) neuronal systems were influenced selectively by specific behavioral tasks. Monoamine concentrations (DA, serotonin and their metabolites) were measured, using high pressure liquid chromatography, in the neostriatum, nucleus accumbens, and medial prefrontal cortex in rats that were either induced to walk forward in a motorized rotating wheel (two speeds) or were exposed to footshock stress (two shock intensities). Our results demonstrate that during locomotor behavior there is an increase in neostriatal DA metabolism, but not in serotonin metabolism. Furthermore, the increase in DA metabolism was found: (a) in both right and left neostriatal nuclei, but with significantly less asymmetry than occurred in non-locomoting control rats; and (b) within the neostriatum at both speeds and also in the nucleus accumbens at the higher speed. Locomotion had no effect on DA metabolism in the prefrontal cortex. With both shock intensities there was increased DA metabolism in the prefrontal cortex, whereas during the low shock intensity there was also an increased DA metabolism in the nucleus accumbens. At the high level of footshock, which evoked jumping and running escape behavior, there was also an increase in neostriatal DA metabolism. These data indicate that a non-lateralized forward locomotor task activates DA metabolism primarily in the less metabolically active hemisphere. Secondly, we found that specific subgroups of midbrain DA neurons can be selectively activated by specific behavioral tasks.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

Head injury in the elderly.

Accounts of head injury tend to be dominated by the findings in young males who constitute the majority of victims. We compare 1571 patients aged under 65 years admitted to the Head and Spinal Injury Unit, Edinburgh in one calendar year with 449 patients aged 65 years or over admitted during two one-year periods. In the elderly group: the sex ratio was equal; falls accounted for the great majority of cases, with pedestrian accidents responsible for serious injuries; alcohol was commonly involved in males; injuries were most frequent on Thursdays; intracranial haematomas and mortality rates were higher; and the length of hospital stay more prolonged. The provisions necessary to meet the needs of the elderly within a head injury service are discussed.

Accidents, Home↗
PubMed1986

Surgical education: the Royal College of Surgeons of Edinburgh specialty examination in surgical neurology.

The origins, concept and structure of the Royal College of Surgeons of Edinburgh specialty examination in surgical neurology are described. The format and content of the examination are compared with the FRACS Part II examination in neurosurgery. Differences in status with respect to recognition of these two diplomas as specialty qualifications are described. The place of the Edinburgh specialty examination in the current and future training and accreditation of neurosurgeons in the United Kingdom is discussed by the authors, an examinee and an examiner in the specialty Fellowship examination.

Accreditation↗
PubMed1986

Spectral analysis of the CSF pulse wave at different locations in the craniospinal axis.

The frequency spectrum and the amplitude transfer function from arterial pulse pressure to the CSF pulse wave were estimated in the lateral ventricle, cisterna magna and lumbar subarachnoid space of anaesthetised ventilated cats under various conditions: (a) normal status, (b) inhalation of 5% CO2 and (c) saline infusion into the CSF space (0.045 ml/min). The CSF pulse waveforms in the lateral ventricle and cisterna magna were almost identical in all conditions. Inhalation of CO2 and saline infusion increased the values of the amplitude transfer function from blood pressure to the CSF pulse wave in the lateral ventricle and cisterna magna to a similar extent. The CSF pulse in the lumbar sac was remarkably damped under both normal conditions and during CO2 inhalation, but the damping was diminished by saline infusion. During the saline infusion, the spinal canal appeared to function as a low-pass filter to the conduction of the CSF pulse.

Animals↗
PubMed1986

Changes of frequency spectrum of the CSF pulse wave caused by supratentorial epidural brain compression.

The frequency spectrum of the CSF pulse wave and amplitude transfer function from arterial to CSF pressure were estimated in the lateral ventricle and cisterna magna during the course of supratentorial epidural compression of brain in anaesthetised ventilated cats. Ventricular fluid pressure, the amplitude of spectral components of the CSF pulse and the amplitude of transfer function in the supratentorial compartment were increased in an exponential manner as epidural compression advanced. A transtentorial pressure gradient developed when epidural compression exceeded a critical level. Conduction of the CSF pulse through the tentorial hiatus decreased in an exponential manner when plotted against the transtentorial pressure gradient. Transtentorial conduction of the CSF pulse may serve as a sensitive indicator of the development of tentorial herniation.

Animals↗
PubMed1986

Nutritional and metabolic support following acute hepatic trauma.

A patient undergoing partial hepatectomy subsequent to trauma was maintained post-operatively on a specifically tailored total parenteral nutrition regimen. This, despite obviously impaired liver function, allowed adequate nutrition without the expected adverse metabolic sequelae associated with hepatic resection and nitrogen loading. The patient also demonstrated, in the absence of normal hepatic tissue, an ameliorated metabolic response to trauma.

Abdominal Injuries↗
PubMed1986

Insulin stimulates amino acid and lipid metabolism in isolated fetal rat hepatocytes.

Although fetal hyperinsulinemia is associated with excessive deposition of glycogen in liver, both in vivo and in vitro studies show little effect of insulin on glycogen synthesis from glucose or the activity of the enzyme glycogen synthase in the fetus. To investigate whether lack of insulin effect extends to other fetal metabolic processes, we compared the influence of insulin on amino acid uptake (14C-alpha-aminoisobutyric acid) and lipid synthesis [14C-acetate) in freshly isolated hepatocytes from 21-day fetal (F) and adult (A) rats. Viability of F and A hepatocytes was documented by trypan blue exclusion (greater than 90%). In A, insulin stimulated 14C-alpha-aminoisobutyric acid uptake in a dose dependent manner with an apparent Km at 2 ng/ml and a Vmax at 10 ng/ml. When corrected for cell surface area, F cells responded to insulin in a similar dose response manner, although absolute values per 1 X 10(6) cells always remained lower. In contrast, whereas A cells demonstrated a typical dose dependent response of 14C-acetate incorporation into lipid with a Km at 5 ng/ml and Vmax at 10 ng/ml of insulin, F cells remained totally unresponsive when the concentration of acetate was 5 mM or less. However, at higher medium acetate concentrations (15-30 mM) fetal responses were equal to or greater than that of adult, both basally and with insulin. These findings suggest differences in the maturation of insulin-mediated processes in fetal rat hepatocytes; effects on amino acid uptake appear earlier than those on lipid or glycogen synthesis.

Amino Acids↗
PubMed1986

Analysis of changes in intracranial pressure and pressure-volume index at different locations in the craniospinal axis during supratentorial epidural balloon inflation.

During experimental supratentorial epidural compression of the brain, cerebrospinal fluid (CSF) pressure and pressure-volume index (PVI) were measured in the supra- and infratentorial compartments of the craniospinal axis in anesthetized ventilated cats. A transtentorial gradient of CSF pressure developed when CSF pressure in the lateral ventricle exceeded 20 mm Hg at balloon volumes of 0.4 to 1.2 ml. The shapes of both the pressure vs. volume and the pressure gradient vs. volume curves were exponential. PVI in the supratentorial compartment was lowered more rapidly as brain compression advanced than PVI in the infratentorial compartment. An index was calculated to represent the relative resistance to the flow of CSF across the tentorial hiatus during supratentorial brain compression. This revealed different resistances to the flow of CSF in the cephalic and caudal directions. A hypothesis concerning the hydrodynamic aspects of the development of tentorial herniation is presented.

Animals↗
PubMed1986

Inaccurate pressure readings for subarachnoid bolts.

The subarachnoid bolt has been used extensively to monitor intracranial pressure in a variety of conditions. We have had two patients who had subarachnoid bolts in place that were thought to be functional in whom evidence of increased pressure was present. In one case, the patient had Reye's syndrome with seizure activity, decerebrate posturing, fixed and dilated pupils, and cardiac arrest. Although autopsy revealed evidence of cerebellar and uncal herniation, verifying the presence of pressure cones, the subarachnoid bolt pressure was never elevated and had a good wave form. In the other case, the patient developed an epidural hematoma postoperatively while a subarachnoid bolt was in place. The subarachnoid bolt was measuring pressures of less than 15 mm Hg with a good wave form despite clinical and, subsequently, computed tomographic evidence of an evolving mass. The use of a pressure monitor such as the subarachnoid bolt should not replace frequent clinical assessment of the patient.

Adult↗
PubMed1986

Correlation of human NMR T1 values measured in vivo and brain water content.

A relationship has been demonstrated between nuclear magnetic resonance (NMR) longitudinal relaxation times (T1 values) obtained in vivo in both normal and oedematous (peritumoral) brain tissue, and measurements of brain water obtained by gravimetric analysis of operative samples. Significant correlations were found in seven patients in both cortex (r = 0.97, P less than 0.001) and white matter (r = 0.92, P less than 0.001). These findings suggest that NMR may prove a useful technique for monitoring brain oedema.

Body Water↗