Biomedical subjects
Publications and source records attributed to J E Thompson.
A case of pulmonary ascariasis is reported for the first time in Australia. Because of increasing immigration from countries which have a high incidence of ascariasis (especially those of South-East Asia), and increasing travel to Asian countries, the awareness of this infestation as a cause of respiratory disease may be of great importance.
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Wide-angle X-ray diffraction studies have indicated that rough and smooth microsomal membranes from bean cotyledons acquire increasing proportions of gel phase lipid at physiological temperature as the tissue senesces. In addition, for both types of membrane the lipid phase transition temperature, defined as the highest temperature at which gel phase lipid can be detected, progressively rises with advancing senescence. Liposomes prepared from total lipid extracts of the membranes show a similar increase in transition temperature with age, indicating that separation of the polar lipids into distinct gel and liquid-crystalline domains is not attributable to peculiar protein-lipid interactions. Liposomes prepared from purified phospholipid fractions of the membranes show little change in transition temperature with age, indicating that the altered phase properties of the lipid do not reflect an increase in fatty acid saturation. However, the formation of gel phase lipid that occurs naturally during senescence can be stimulated by preparing liposomes from a mixture of the phospholipid fraction from young membrane and the neutral lipid fraction from old membrane. By adding the separated components of the neutral lipid fraction to purified phospholipid it was found that sterol esters and several unidentified lipids are able to raise the transition temperature of the polar lipids. Sterols have no effect on the phospholipid transition temperature. The data have been interpreted as indicating that several neutral lipids, which presumably increase in abundance with advancing senescence, induce a lateral phase separation of the polar lipids resulting in distinct gel and liquid-crystalline domains of lipid in the senescent membranes.
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Hypersensitive carotid sinus is a rare cause of spontaneous syncopal attacks. It must be differentiated from the other more common causes, such as intrinsic cardiac disease, vasovagal responses, postural hypotension and cerebrovascular insufficiency, although it may accompany these conditions. The definition of carotid sinus syncope is syncope elicited by stimulation of a hypersensitive carotid sinus. Nineteen patients with carotid sinus syncope were treated by carotid sinus denervation. Ages ranged from 48 to 83 with a mean of 65.5 years. Symptoms of marked dizziness or syncope were reproduced by gentle compression over the carotid bifurcation, while ECG monitoring revealed bradycardia or transient asystole. Seventeen patients had carotid arteriograms, eleven of which were normal. One patient had stenosis of the external carotid artery, while five had stenosis of the internal carotid. The right carotid sinus was involved in ten patients, the left in three and both sides in six. All patients underwent unilateral or bilateral carotid sinus denervation. Five patients with internal carotid stenosis had concomitant carotid endarterectomy. Complete relief of symptoms or marked improvement was noted in all but one patient. Postoperative follow-up ranged up to 15 years. Carotid sinus denervation is a simple, effective method of treating this disorder.
The effects of stigmasterol, sitosterol, campesterol, and cholesterol on the phase properties of dipalmitoylphosphatidylcholine bilayers have been compared by differential scanning calorimetry and x-ray diffraction. The sterols were equally effective at progressively reducing the cooperativity and the enthalpy of the dipalmitoylphosphatidylcholine phase transition as their concentrations in the bilayer were increased. Moreover, both differential scanning calorimetry and x-ray diffraction indicated that the dipalmitoylphosphatidylcholine transition was eliminated by each of the sterols when they were present at a concentration of 33 mole%. This indicates that the interaction between phospholipid and both plant and animal sterols is stoichiometric, each sterol associating with two phospholipid molecules. At concentrations above 33 mole% the sterols were no longer completely solvated by the phospholipid, and sterol-sterol interaction resulted. Cholesterol, even at concentrations as high as 50 mole%, did not disrupt the lamellar structure of the bilayer. When these high concentrations of plant sterols were intercalated into the phospholipid, crystallinity, which presumably derives from sterol-sterol interaction, was detectable in the bilayer by x-ray diffraction. This observation is consistent with previous reports to the effect that the C(17) chains of the plant sterols render them less soluble in phospholipid than is cholesterol. It is clear that this solvation difference is of insufficient magnitude to affect the stoichiometry of dipalmitoylphosphatidylcholine-sterol interaction, but it could well account for the less effective modulation of lipid bilayer permeability exhibited by plant sterols in comparison with cholesterol.
Wide angle x-ray diffraction has been used to examine the phase behavior of microsomal membranes from regressing corpora lutea of prepubertal pseudopregnant rats. During periods of optimal progesterone secretion, all of the membrane lipid was in the liquid-crystalline phase at physiological temperature and, therefore, was fluid. However, mixtures of liquid-crystalline and gel phase lipid were observed under identical conditions in microsomal membrane preparations from animals undergoing spontaneous or prostaglandin F2 alpha-induced regression. This was accompanied by a parallel rise in the lipid phase transition temperature. In addition, the proportion of lipid in the gel phase increased with time after prostaglandin F2 alpha treatment. These results indicate that the mechanism of corpus luteum regression may involve phase changes in the phospholipid bilayer of cellular membranes. The resulting presence of gel phase lipid in the membrane matrices could contribute to the loss of tissue function.
There are two major categories of post-traumatic pain syndroms: (1) causalgia; and (2) mimocausalgia states or reflex sympathetic dystrophy. Vasoconstriction is usually present. Because of the pain, limitation of motion of the extremity occurs, and may result in permanent disability. There is often a great disparity between the apparent trauma and the severity of the pain. Sympathetic blocks and sympathectomy are definitive modes of therapy. In a series of 147 patients, 56% required surgical sympathectomy. The rest were treated by sympathetic blocks, physical therapy, and other medical measures. Eighty-two percent had excellent relief of pain, 11% had good relief, while 7% had no relief. Thirty-one percent of patients had residual symptoms resulting from the original injury, or from irreversible occurrences on the basis of pain and trophic changes. Emphasis is placed on early recognition and proper treatment.
A nontender, nonpulsatile large anterior neck mass was found at operation to be an atherosclerotic aneurysm of the vertebral artery, an extremely rare condition. Proximal control and distal control were obtained and the aneurysm was excised. Aneurysms of the vertebral artery are infrequent but well-defined complications in connective tissue disorders such as the Ehlers-Danlos syndrome, and they can develop subsequent to penetrating neck trauma. However, no cases of atherosclertic vertebral artery aneurysms have been reported recently in the English-language literature. The case presented illustrates that this rare condition should be considered in all patients who have neck masses of undetermined etiology.
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We have adapted for glucose determination a new approach to kinetic analyses [Anal. Chem. 50, 1611 (1978)]; it is 50-fold less dependent upon some experimental variables than is a more conventional rate method. Modification of a commercially available hexokinase/glucose-6-phosphate dehydrogenase reagent system for glucose provides that the rate of production of NADH be first-order in total glucose concentration within about 30 s after sample and reagent are mixed. In the kinetic method, absorbance vs. time data recorded after 30 s and a multiple-linear-regression program are used to compute the absorbance change that would occur if the reaction were monitored to completion. Results demonstrate a linear relationship between glucose concentration and computed absorbance change. Application of the method to 51 human sera without rigorous control of either temperature or reagent composition yielded a regression equation of y = 1.01x -0.3 when kinetic results (y) were compared with equilibrium results (x) for the same samples analyzed in a hospital laboratory.
The combination of 20 mg xylazine/kg of body weight and 100-150 mg ketamine/kg of body weight provided satisfactory levels of anesthesia in 63 prairie dogs, and the combination was tolerated well with a mortality rate of 3.2%.
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The phospholipid content of rough and smooth microsomal fractions from cotyledons of germinating bean declines as the tissue becomes senescent. Both types of membrane contain comparable proportions of three major phospholipids, phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol, which collectively comprise about 90% of the total. This proportionality does not change appreciably during senescence. Only small quantities of lysophosphatides were noted at all stages of senescence. The unsaturated:saturated fatty acid ratio for total extracted lipid declined only slightly in both membrane systems, but pronounced differences in this ratio were observed among the major phospholipids of the membranes. The most striking alteration in lipid composition with advancing senescence was an increase in the sterol:phospholipid ratio; this rose by about 50% for rough microsomes and 400% for smooth microsomes. For both types of membrane the patterns of change in this ratio correlated with previously reported changes in bulk lipid transition temperature, suggesting that the increase in sterol level may contribute to changes in phase behaviour of the membranes during senescence. Arrhenius plots of rotational correlation times for the electron spin label 2,2-dimethyl-5-dodecyl-5-methyloxazolidine-N-oxide (2N14) partitioned into the membrane lipid showed an increase in viscosity with advancing senescence and a corresponding increase in activation energy for both types of membrane. These changes in activation energy and viscosity correlated closely with the increase in sterol:phospholipid ratio. However, no phase transitions were detectable between temperatures of 2 and 55 degrees C despite the fact that transitions from a lipid-crystalline to gel state are detectable within this temperature range by wide angle X-ray diffraction.
The complications of isoniazid (INH) were studied in 1033 patients, who had received INH for at least 18 months, with or without other drugs. Hepatitis developed in 25 patients; this was attributed to rifampicin, (15 cases); infectious hepatitis (three cases); INH alone, (three cases); IHN possibly exacerbating chronic liver disease, (two cases); and multiple drug treatment, (two cases). Central nervous system disorders (mainly peripheral neuropathy) due to INH occurred in 12 patients, all of whom were over the age of 40 years. Hypersensitivity to INH developed in 12 patients. Some difficulties in distinguishing hepatitis due to rifampicin from that due to INH are discussed. When the risk of hepatitis was compared with the risks of developing, or dying from, tuberculosis, it was found that the benefits of INH chemoprophylaxis outweighed the risks, particularly in patients who were less than 50 years of age.
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