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Biomedical subjects

J Bland

Publications and source records attributed to J Bland.

At least 37 records · Page 2Linked to original sources
PubMed1987

Double peak attenuation method for estimating organ location.

Radioactive sources of finite volume containing 133Xe, 67Ga, 99Tcm and 111In were used to measure the attenuation coefficient, mu, in water at six different energies in the range 80-296 keV using an Anger camera. The experimental accuracy was about 7% for the volume range from 40-225 ml when corrections were made for background. The same radioactive sources were used to measure zero attenuation count rates per unit of activity. The theoretical basis was also derived, which confirms our experimental findings, i.e. the measurement of the thickness of the attenuator using a dual energy method. The determination of the linear attenuation coefficient in the broad-beam geometry situation is possible by accounting for cross-talk, scatter and out-of-target activity. By correcting for the broad-beam geometry, agreement with the narrow-beam geometry linear attenuation coefficient was obtained. We also demonstrate the use of the technique to accurately determine the depth of the organ using two separate energies. This methodology is independent of the organ volume for determination of the depth. It is hoped that our findings will provide a better understanding of the photon interactions when extended sources are used. Such a knowledge can also be applied to organ volume measurements.

Humans↗
PubMed1986

The osmotic thresholds for thirst and vasopressin release are similar in healthy man.

The relationship between thirst perception and plasma osmolality was studied during hypertonic and physiological saline infusion in ten healthy volunteers. Thirst perception was quantified using a linear visual analogue scale which volunteers marked at intervals during the infusion periods. Infusion of hypertonic saline caused a steady rise in plasma osmolality together with a progressive linear increase in thirst perception and also plasma arginine vasopressin. No significant changes in thirst, plasma osmolality or plasma arginine vasopressin occurred during infusion of physiological saline. Linear regression analysis of the results defined the functions. Thirst (cm) = 0.3 (plasma osmolality-281) (r = +0.92, P less than 0.001) and plasma arginine vasopressin (pmol/l) = 0.4 (plasma osmolality-285) (r = +0.96, P less than 0.001). The osmolar threshold for thirst onset thus defined (281 mosmol/kg) was much lower than in previous studies and similar to the theoretical osmolar threshold for vasopressin release (285 mosmol/kg). We conclude that thirst perception rises in a progressive fashion throughout a wide range of plasma osmolality and that the osmolar threshold for thirst onset is similar to the theoretical osmolar threshold for vasopressin release. The results are compatible with the concept of either a single osmoreceptor subserving both thirst and vasopressin release, or two osmoreceptors sharing similar functional characteristics.

Adult↗
PubMed1986

Early intimal lesions in the common carotid artery.

Histological sections of the common carotid arteries from 259 children who were stillborn or died under 16 years of age were examined for intimal thickening, lamellar irregularities and ruptures, foam cells, and fat. Lesions were present at birth in approximately half the children examined, and the incidence increased rapidly in the first two months after birth. All the children had the early features of the prodroma of atheroma by 8 months of age. Compared with the findings of previous studies of the coronary arteries and aorta the histological findings appeared in the carotid arteries at an earlier age. The prevalence of intimal lesions in infant cot deaths, chronic diseases, and congenital heart disease was compared with that in all other children in the study. There was no difference in the cot death group, but in children under 2 years in both the chronic disease and heart deformity group there was a lower incidence of intimal thickening and visible fat.

Acute Disease↗
PubMed1986

Wilson's disease in two siblings--one with fatal outcome.

The clinical and biochemical findings in two siblings with Wilson's disease are described. One of them, an 11-year-old girl, developed acute liver failure terminating in death within a few weeks. Prior to her terminal illness she had been in good health without symptoms suggestive of Wilson's disease. Copper contents of urine, liver, kidney and brain were 20-100 times above the upper normal limits. The liver showed extensive micronodular cirrhosis with nonbile pigment deposits. Her 15-year-old brother had abnormal liver function tests with urinary copper excretion 20 times above the upper normal limit. Treatment with penicillamine was started. Following a short period of deterioration his condition has steadily improved.

Adolescent↗
PubMed1983

Bioassay procedures for norfloxacin.

A disk-diffusion bioassay procedure for the quantitation of norfloxacin in serum, tissue and urine employing Klebsiella pneumoniae ATCC 10031 was developed. When incubated at 28 degrees C, the assay has a sensitivity of 0.2 microgram/ml. Zones of inhibition on assay plates may be measured by hand (ruler, vernier caliper) or by automated image analysis. Urine samples require an initial 1:2 dilution in 0.1N HCl before assay to assure complete solution of the compound. Bioassay values in urine are comparable to those obtained by high performance liquid chromatography.

Anti-Bacterial Agents↗
PubMed1981

Actions of gamma-radiation on resealed erythrocyte ghosts. A comparison with intact erythrocytes and a study of the effects of oxygen.

With respect to both permeability and inactivation of membranous GAPDH, ghosts were more susceptible than erythrocytes to free radicals produced in the gamma-irradiation of aqueous solutions. The rate of increase in the permeability of irradiated ghosts was immeasurably greater than that of irradiated erythrocytes, while the rate of inactivation of GAPDH was 21-fold greater. The sensitivity of ghosts to radiation damage was affected strongly by the presence of oxygen during irradiation. In the presence of air, the rates of increase of permeability and inactivation of GAPDH were 2.8- and 1.5-fold of those in the presence of N2. The use of buffer saturated with oxygen accelerated the aerobic rates of increase of permeability and inactivation of GAPDH by 60- and 2.7-fold. These results indicate that inactivation of GAPDH is somewhat sensitive to oxygen, particularly at high concentration of oxygen. Nevertheless, in air or under nitrogen, the rate of enzymic inactivation was almost an order of magnitude greater than that of increase of permeability, indicating that the former is much more sensitive to irradiation. The major mechanism of the oxygen effect observed is the ability of oxygen to increase the branching of the free radical chain reactions which propagate damage after initiation within the membrane.

Cell Membrane Permeability↗
PubMed1978

Effect of tocopherol on photooxidation rate of human erythrocyte membrane in vitro.

Study indicates that tocopherol's ability to prevent erythrocyte photohemolysis is a result of selective chemical trapping of the photooxidation-generated oxidant, singlet oxygen, before it can cause peroxidation of the essential unsaturated lipids in the erythrocyte membrane. The data provide fundamental information that support the purported clinical efficacy of tocopherol in the treatment of congenital erythrocyte membrane oxyhemolysis.

Erythrocyte Membrane↗
PubMed1977

Acinic cell tumors of salivary gland origin.

The acinic cell tumor of salivary gland origin, once thought to be benign, is now known to be an incidiously slow growing malignant neoplasm with lethal potential. While the degree of malignant behavior of individual acinic cell tumors is notably variable, all must be treated with aggression. Traditional and current methods of treatment are reviewed; and, in conjunction with the tumors herein reported, guidelines for managment of this uncommon malignancy are suggested. Four cases have been reviewed in detail and critically analyzed. The pathology, including features of both light and electron microscopy, in included--particularly in relation to the oncocytoid areas identified in from 10% to 40% of the parenchymal cells of our tumors. Since an accurate histopathologic diagnosis is the first step in the establishment of a proper treatment plan, pitfalls in histologic diagnosis have been stressed.

Adult↗
PubMed1975

Effect of alpha-tocopherol on the rate of photohemolysis of human erythrocytes.

The results of this study demonstrate that alpha-tocopherol has a significant ability in vivo to prohibit the production of cholesterol hydroperoxide in the erythrocyte membrane, and also significantly reduce the degree of cell membrane deformation upon exposure of the blood to light and oxygen (photooxygenation conditions). This study suggests that alpha-tocopherol prohibits the production of cholesterol hydroperoxide in the membrane which if produced leads to a weakened membrane observed as a "budded" cell in the electron micrographs.

Animals↗
PubMed1974

Isolation and characterization of bacteria that grow on methane and organic compounds as sole sources of carbon and energy.

Bacteria capable of growth on methane and a variety of complex organic substrates as sole sources of carbon and energy have been isolated. Conditions used to rigorously establish the purity of the cultures are described. One facultative methylotroph has been studied in detail. This organism has peripherally arranged pairs of intracytoplasmic membranes characteristic of obligate methylotrophs. This isolate apparently utilizes the serine pathway of formaldehyde fixation. The location of methane oxidizers in a dimictic lake indicates that these organisms prefer less than saturating levels of dissolved oxygen. Laboratory experiments confirmed the preference of these organisms for atmospheres containing less oxygen than air.

Anti-Bacterial Agents↗