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Biomedical subjects

G Forbes

Publications and source records attributed to G Forbes.

54 records · Page 3Linked to original sources
PubMed1984

Complications of cerebral angiography: prospective assessment of risk.

A prospective study of 1,517 consecutive cerebral angiographic examinations is reported. The incidence of all complications was 8.5%, and the incidence of all neurologic complications was 2.6%. The overall incidence of permanent neurologic deficit was 0.33%. The incidence of permanent neurologic deficit in patients referred for evaluation of symptomatic cerebrovascular disease was 0.63%. Older age, increased serum creatinine concentration, and the use of more than one catheter all were significantly associated with serious neurologic complications. Although patients with a recent stroke or frequent transient ischemic attacks had a higher incidence of serious neurologic complications, this increase was not statistically significant for this sample.

Adolescent↗
PubMed1984

Kallikrein-kinins in the central nervous system.

We studied whether the components of the kallikrein-kinin system are present in the central nervous system. We found that human cerebrospinal fluid (CSF) contains free kinins: 53 +/- 15 pg/ml; kininogen: 10.9 +/- 2.1 ng kinin equivalent/ml, and kininogenase activity: 5.0 +/- 2.1 ng kinins/ml/minute. Kininogenase activity was 2-3 fold augmented by preincubation with trypsin. Soybean trypsin inhibitor completely inhibited untreated CSF and partially inhibited trypsin activated kininogenase. Kininogenase activity and immunoreactive glandular kallikrein were present in rat brain, and their concentrations in hypothalamus is several-fold higher than in cortex, pons-medulla, basal ganglia and cerebellum. In the hypophysis, activity in pars-intermedia was between 6- and 20-fold higher than in posterior and anterior hypophysis, respectively. High activity was also found in the pineal gland. The kallikrein-kinin system is present in the central nervous system where it may participate in modulation of nervous and neuroendocrine functions.

Animals↗
PubMed1983

Intakes of copper, zinc, cadmium, tin, iron, nickel and arsenic in a population exposed to lead from water.

Adult diets obtained from a population in Ayr, Scotland, U.K., known to be exposed to lead from water were analysed for arsenic, cadmium, copper, iron, nickel, tin and zinc to assess the intake of these elements. With few exceptions, the concentration of each element varied little from diet to diet, and therefore the range of intakes varied only in proportion to the weights of the diets. With the exception of nickel, the difference between the observed average dietary intakes of the metals studied and those expected on the basis of a nationwide Total Diet Study is largely accounted for on the basis of the differences between the weights of the duplicate diet and the weight for the Total Diet Study.

Adult↗
PubMed1983

The assessment of muscle mass in progressive neuromuscular disease.

We performed sequential studies of two methods used to estimate muscle mass in 34 patients with progressive neuromuscular disease for periods of up to 52 months. Creatinine excretion and total body potassium were low at the outset in virtually all patients. Creatinine excretion continued to decline in most patients, but total body potassium did not decline significantly. Creatinine excretion may measure declining muscle mass more accurately than total body potassium, but both measurements can estimate muscle mass for metabolic studies or therapeutic trials.

Adolescent↗
PubMed1982

Computed tomography of the orbit.

Computed tomography has become accepted as the key modality in orbital radiography. Good technique with axial and coronal positioning on high-resolution scanners provides excellent imaging of major orbital structures, including the globe, ocular muscles, optic nerve, and major vessels. Examinations may be tailored specifically for orbital diagnosis or may be appropriately incorporated in scanning of the head. Sufficient data are provided by CT for accurate detection and, in many instances, diagnosis of tumor. Findings may help differentiate inflammatory conditions, endocrine ophthalmopathies, and neoplasm. The CT examination is also of assistance in evaluating facial and orbital trauma and in demonstrating the presence of a pathologic process in the periorbital regions.

Diagnosis, Differential↗
PubMed1981

Cellular basis for the loss of carcinogen from methylcholanthrene-impregnated Millipore membrane.

Millipore 'discs' impregnated with methylcholanthrene dissolved in wax or in crystalline form implanted subcutaneously in mice evoke an early intense macrophage and giant cell reaction; later the discs become covered with connective tissue, and eventually fibrosarcomas develop in their vicinity. Studies with tritium-labelled material show that under these conditions methylcholanthrene (MC) is removed from the discs and broken down rapidly (half life about 7 days) to a water-soluble product, which diffuses locally, is distributed widely via the blood stream, and is excreted in faeces and urine. Removal of label is halted by whole-body irradiation (550 R) with the disc area shielded; this observation, in conjunction with the histological and autoradiographic findings and the paucity of label in cells stripped from excised discs, points to the conclusion that the removal of MC from impregnated discs, and its subsequent degradation, depend on the presence of macrophages and the continual replacement of spent macrophages by new cells generated centrally. The rate of disappearance of label from implanted [3H]MC discs was not altered by administration of Corynebacterium parvum; this, however, does not exclude the possibility that the metabolic pathways involved in the removal of MC are altered. To investigate this it is proposed to study, in both normal mice and mice treated with C. parvum, the extent to which cytochrome P450 and other enzymes concerned in the activation and detoxification of polycyclic hydrocarbons by liver microsomal fractions are inducible in the macrophages that accumulate in inflammatory exudates. This histological techniques used should be readily applicable to the study of the early stages of chemical carcinogenesis and the host reaction to transformed cells.

Animals↗
PubMed1972

Sexual offences.

Explore the source record for details and available documents.

England↗
PubMedDate not supplied

Phantom testing of peripheral artery. Absolute blood flow measurement with digital arteriography.

A technique to measure absolute arterial blood flow in ml/min has been developed utilizing software programs with high-speed digital recording for the off-line analysis of intra-arterial injections of contrast medium. Measurements of pulsatile flow in a phantom for a physical flow model showed that calculations with the final upgrades were within 10% of known flow, using a recording rate of 30 frames/s, a diameter tubing of 5 mm, and flow rates of 300 to 400 ml/min. Quantitative absolute flow of a peripheral artery such as the internal carotid artery may be obtained during routine cerebral arteriography for comparison with anatomic data.

Angiography↗
PubMedDate not supplied

Temporal lobe volume measurement from MR images: accuracy and left-right asymmetry in normal persons.

The effect of several magnetic resonance (MR) variables on the accuracy of volume measurements in phantom objects was investigated by use of an off-line automatic border-outlining and internal area pixel-counting computer program, and an optimal set of imaging variables was identified. Measurements were made of the temporal lobe volumes of a gross fixed brain specimen from MR image data. The range in accuracy was from -2 to +7%, and the standard deviation of the difference in right minus left lobe volume measurements obtained from the MR images and those obtained by use of Archimedes' principle was 1 cm3. This volumetric technique was applied to 25 normal persons, most of whom were right-handed. The median ratio of right to left temporal lobe volume was 1.16 (range 0.99-1.23). The nondominant temporal lobe was significantly larger than the dominant. The mean difference (95% confidence interval) between right and left volumes was 7 cm3 (6-9 cm3). This confidence interval was similar to that obtained when the variability within a subject (estimated from the gross fixed brain specimen) was taken into account. Unilateral temporal lobe atrophy, particularly in patients with temporal lobe epilepsy, should be interpreted from MR images with this range of discrepancy in normal left-right size in mind.

Adult↗
PubMedDate not supplied

Ophthalmopathy of Graves' disease: computerized volume measurements of the orbital fat and muscle.

Pixel-calibrated volume measurements of muscle and fat in the bony orbit were made from CT scans of 72 patients with Graves' disease, with and without ophthalmopathy, to define characteristic changes present in clinical subgroups. Measurement abnormalities were detected in 87% of Graves' patients with clinically detectable ophthalmopathy and in 70% of hyperthyroid patients without clinical eye signs. Abnormal enlargement of the fat compartment in addition to muscle enlargement was found in 46% of patients with clinical ophthalmopathy; 8% of patients had only increased size of the fat compartment with normal muscle volumes. The ratio of muscle to fat and the volumes of orbital muscle and fat all varied widely in each clinical subgroup. Statistically significant (p less than 0.0001) total muscle-volume increase (range = 3.68-17.06 cm3) and borderline significant (p less than 0.06) fat-compartment increase (range = 6.05-22.63 cm3) were documented in all clinical subgroups. The degree of change of muscle and fat volumes was independent of the clinical group. Abnormal changes were found in the contralateral orbit in six of seven patients who appeared to have unilateral ophthalmopathy on clinical examination. A higher frequency of medial and inferior muscle enlargement was documented in all clinical subgroups.

Adipose Tissue↗
PubMedDate not supplied

Polyvinyl alcohol sponge for embolotherapy: particle size and morphology.

The size and morphology of particulate polyvinyl alcohol (PVA) sponge prepared by a blender technique for embolotherapy were analyzed by light and scanning electron microscopy. Techniques for preparation and sizing of PVA sponge particles are described. Two types of particulate material, differing in both size and morphology, were found. Large particles (greater than 50 micron) had irregular shapes and sharp, jagged edges. Smaller particles (2-50 micron) were more numerous. Attempts to characterize the smaller particles were unsuccessful. Preparation of PVA sponge particles using the blender technique is a viable choice in external carotid neuroembolization procedures. However, the potential effects of small particles possibly causing cranial nerve palsies does need consideration.

Animals↗
PubMedDate not supplied

Computer analysis of orbital fat and muscle volumes in Graves ophthalmopathy.

A technique using special computer programs and data from high-resolution computed tomographic scans has been developed that provides accurate and reproducible volume measurements for muscle and fat in the orbit. Normal values for retrobulbar fat and muscle were established in 19 adults. Nineteen patients with Graves exophthalmopathy were then studied, and a spectrum of change was found that included varying degrees of increased muscle volume or increased volume of both muscle and fat. Further categorization of these changes related to clinical characteristics should lead to a better understanding of the mechanism for ophthalmopathy in Graves disease.

Adipose Tissue↗