Showing papers by "St Bartholomew's Hospital published in 1969"

Lipid peroxide formation in microsomes. General considerations

Abstract: 1. Liver microsomes form lipid peroxide when incubated with ascorbate or NADPH, but not with NADH. Increasing the concentration of ascorbate beyond the optimum (0.5mm) decreases the rate of lipid peroxide formation, but this effect does not occur with NADPH. Other reducing agents such as p-phenylenediamine or ferricyanide were not able to replace ascorbate and induce lipid peroxide formation. 2. The rate of ascorbate-induced peroxidation is optimum at pH6.0 whereas the rate of the NADPH system is optimum at pH7.0. Both systems require phosphate for maximum activity. 3. Lipid peroxide formation occurs at the maximum specific rate in very dilute microsome suspensions (0.15mg. of protein/ml.). 4. Treatment of microsomes with deoxycholate and other detergents causes membrane disintegration and inhibits lipid peroxide formation. 5. Lipid peroxide formation is accompanied by a rapid uptake of oxygen and there is a large excess of oxygen utilized for each molecule of malonaldehyde measured in the peroxide method. 6. Boiled microsomes form lipid peroxide in the presence of ascorbate, but not if NADPH is added. 7. Lipid peroxide formation induced by NADPH is strongly inhibited by p-chloromercuribenzoate, weakly inhibited by N-ethylmaleimide and unaffected by iodoacetamide. Ascorbate-induced peroxidation in untreated microsomes is unaffected by p-chloromercuribenzoate, but inhibited if boiled microsomes are used. These experiments may be interpreted on the basis that a ferredoxin-type protein forms part of the system in which NADPH induces lipid peroxide formation. 8. Most heavy-metal ions, with the exception of inorganic iron (Fe(2+) or Fe(3+)), which activates, inhibit both ascorbate-induced and NADPH-induced peroxidation. Mg(2+) increases the rate of peroxidation whereas Ca(2+) inhibits it. 9. Lipid peroxide formation is inhibited strongly by GSH and weakly by cysteine. Ascorbate-induced peroxidation is much more sensitive than NADPH-induced peroxidation. 10. Peroxidation is strongly inhibited by addition of low concentrations (0.01-0.1mm) of cytochrome c or of haemoglobin. 11. It is considered that lipid peroxide formation occurs as a result of the operation of the microsomal electron-transport chain switching from hydroxylation to oxidize unsaturated lipids of the endoplasmic reticulum.

The urethral pressure profile.

Abstract: SUMMARY Continuous pressure profiles would seem to include all possible advantages over other methods of urethral assessment. The method applies equally to electro-stimulation testing and to the evaluation of stricture. A wide range of variations and refinements to the method may be suggested, for instance, the profile catheter should preferably be withdrawn at a known steady rate, and this could perhaps be achieved by a mechanical device. It might also be useful if subsequent profiles could be superimposed on the initial trace to allow of a more accurate comparison between sequential examinations. Perfectly adequate results may however be obtained with the simple apparatus described above.

Lipid peroxide formation in microsomes. The role of non-haem iron.

Abstract: 1 Metal ion-chelating agents such as EDTA, o-phenanthroline or desferrioxamine inhibit lipid peroxide formation when rat liver microsomes prepared from homogenates made in pure sucrose are incubated with ascorbate or NADPH 2 Microsomes treated with metal ion-chelating agents do not form peroxide on incubation unless inorganic iron (Fe2+ or Fe3+) in a low concentration is added subsequently No other metal ion can replace inorganic iron adequately 3 Microsomes prepared from sucrose homogenates containing EDTA (1mm) do not form lipid peroxide on incubation with ascorbate or NADPH unless Fe2+ is added Washing the microsomes with sucrose after preparation restores most of the capacity to form lipid peroxide 4 Lipid peroxide formation in microsomes prepared from sucrose is stimulated to a small extent by inorganic iron but to a greater extent if adenine nucleotides, containing iron compounds as a contaminant, are added 5 The iron contained in normal microsome preparations exists in haem and in non-haem forms One non-haem component in which the iron may be linked to phosphate is considered to be essential for both the ascorbate system and NADPH system that catalyse lipid peroxidation in microsomes

Lipid peroxide formation in microsomes. Relationship of hydroxylation to lipid peroxide formation.

Abstract: 1. Aminopyrine strongly inhibits NADPH-induced lipid peroxide formation in rat liver microsomes, but ascorbate-induced peroxidation is inhibited to a smaller extent. 2. Aminopyrine oxidation is stimulated by Mg(2+) but inhibited by Ca(2+). Concentrated solutions (10mm) of iron-chelating agents inhibit aminopyrine oxidation, but the more dilute solutions (0.5mm) of chelators that block lipid peroxide formation do not inhibit aminopyrine oxidation. Microsomes prepared from sucrose-EDTA homogenates rapidly oxidize aminopyrine, but do not form lipid peroxide when incubated with ascorbate or NADPH. 3. Aminopyrine oxidation is strongly inhibited by p-chloromercuribenzoate, less by iodoacetamide and weakly by N-ethylmaleimide. The site of action of these compounds is considered to be a ferredoxin-type protein. GSH and cysteine also inhibit. 4. Other drugs oxidized by microsomes such as caffeine, phenobarbitone and hexobarbitone had either no or little effect on lipid peroxide formation, but codeine inhibited. 5. Most aliphatic hydrocarbons, alcohols, ketones and aldehydes did not affect lipid peroxide formation, but chloroform and carbon tetrachloride inhibited. 6. Many aromatic compounds inhibited lipid peroxide formation. Only aromatic acids were without any effect and phenols and amines were very strong inhibitors. 7. Induction of lipid peroxide formation in microsomes by incubation with ascorbate or NADPH or by treatment with ionizing radiation leads to a sharp decline in the ability of microsomes to oxidize aminopyrine or hydroxylate aniline. 8. It is considered that the two processes of hydroxylation and lipid peroxide formation are closely linked in microsomes. They probably depend on the same electron-transport chain, and peroxide formation, which involves membrane disintegration, may be part of the normal membrane remodelling process.

Corticosteroid treatment and surgery

Abstract: The first post-operative death presumed to be due to adrenocortical suppression following corticosteroid therapy occurred in 1952 1. Similar reports followed2-5, but it was not until 1961 that Sampson, Brooke & Winstone 6 demonstrated an abnormally low level of plasma cortisol (hydrocortisone) in a steroid-treated patient who had suffered a severe fall in blood pressure during operation. They reported a similar case the following year7 and recently a third has been recorded8, but these appear to be the only instances in the literature of post-operative collapse unequivocably due to adrenocortical failure. Other conditions, such as unrecognized blood loss, myocardial infarction and septicaemia, can produce a similar clinical picture and in these situations large doses of hydrocortisone will often raise the blood pressure by a direct inotropic action on the heart and other non-specific effectsg~lo. Many reported cases of collapse have undoubtedly been due to causes other than adrenocortical insufficiency and, as Copell has pointed out, ‘the vast majority of such incidents seem to be associated with medical diagnostic, and not adrenal failure’. Nevertheless, it has been the usual practice to give large quantities of steroids to ‘cover’ operations in all patients who have received these drugs within the previous two years59 12. This is obviously undesirable in those with normal adrenal function, since corticosteroids may increase susceptibility to infection 1 315, retard healing161 1 5 , precipitate gastro-intestinal haemorrhage 1 7 ,18 and impair electrolyte balance 1 99 1 8. In this and the following paper an attempt is made to clarify the use of steroid cover, and to answer two questions : 1 Which patients treated with corticosteroid drugs require cover for surgery ? 2 What form should that cover take?

The hominoid wrist joint.

Abstract: In a previous study of the primate wrist joint the author has shown that this articulation is uniquely modified in the Pongidae by the interposition of a meniscus between the ulnar styloid process and the carpus. This meniscus (which in gibbons contains a bony lunula) partially isolates the ulnar styloid process in a proximal synovial compartment. The human wrist joint is clearly derived from such an articulation, the proximal synovial compartment persisting as the prestyloid recess. The present paper is concerned with observations on a wider range of hominoid material. A spectrum of variations is demonstrated, largely the result of a tendency for the neomorphic meniscus to be incorporated as an integral component of the proximal articular surface, thereby progressively excluding the ulnar styloid process from the wrist joint and constricting the entrance to the proximal synovial compartment. The unique construction of the hominoid wrist joint is considered to be a specialization facilitating pronation-supination. Such free rotatory movement is a necessary prerequisite for true brachiation, and the obvious phylogenetic implication is that Homo has shared a brachiating ancestry with the Pongidae. This is convincing evidence in favour of the view that a period of brachiation provided the essential apprenticeship for the complex locomotor activities of bipedal, tool-using man.

Studies on the structure and function of the mammalian testis. II. Cytological and histochemical observations on the testis of the rat after a single exposure to heat applied for different lengths of time.

Abstract: The scrotal regions of five groups of rats were exposed to a temperature of 43 degrees C for progressively longer periods, ranging from 10 to 30 min in steps of 5 min. The animals were then killed at 3 days, 7 days, 3 weeks and 6 weeks after heat-treatment, and their testes examined by various cytological and histochemical procedures. Appropriate control animals were killed alongside the experimental groups. There was essentially no change seen in the 10 min group. In the 15 min group two critical periods were established where further development of the germ cells failed; the first occurred as cells in the early transitional condition attempted to develop into late transitional forms, while the second operated from late pachytene to the end of the maturation division. This led to what has been termed the pattern of mild heat damage. As the exposure time was increased the pattern of mild heat damage was extended, and after 20 min the two critical periods merged. A third also began to appear, such that while cells in the Golgi phase were able to form cap-phase cells they could not develop into acrosome-phase spermatids. Twenty-five minutes exposure produced a similar result but the third critical period was then firmly established, since neither the Golgi or cap-phase spermatids developed into acrosome-phase spermatids. After 30 min all the previous critical periods were extended and merged and their extreme boundaries marked two new critical periods, one operating at the spermatogonial level and the other at the acrosome-phase. In animals treated for 15, 20 and 25 min there was a variable degree of recovery which occurred between 7 and 21 days after heating, during which time the critical periods disappeared. The damage to the germinal epithelium was accompanied by an increase in the lipid content of the Sertoli cells which progressively gave a red colour with Nile blue (non-acidic) and a positive reaction to Schultz's test for unsaturated sterols. This effect is interpreted as an indirect one resulting from the damage to the germinal epithelium and the cessation of spermatogenic activity. The high lipid/sterol content of the Sertoli cells was reduced to normal levels with the recovery of the germinal epithelium, notably during the maturation division of the primary and secondary spermatocytes corresponding to stages IX-XIV of the cycle of the seminiferous epithelium. Injections of follicle-stimulating hormone (FSH) into rats exposed to the heat for 30 min did not reduce the lipid/sterol content of the Sertoli cells to normal levels as found previously when the same gonadotrophin was administered to oestrogen-treated rats. This is attributed to the extensive damage caused to the germ cells in the 30 min group. The work on the heat-treated animals provides further evidence in support of the view that the lipids/sterols of the Sertoli cells represent material normally utilized by the germ cells in the course of their development; it emphasizes that the cells which primarily use this material are the spermatocytes and finally suggests that the last-mentioned cells govern or regulate sterol metabolism by the Sertoli cells. The Leydig cells in all groups appeared to be unaffected by the heat-treatment.

The Effects of Altitudinal Variation in Ethiopian Populations

Abstract: A study has been made of three neighbouring populations living at 1500, 3000 and 3700 m in the northern Simien of Ethiopia. The environments of these populations not only differ in many climatic elements, but also probably in nutritional factors and exposure to infections. The growth and physique of the people vary with altitude and the lowlanders (at 1500 m) tend to have a more linear body build. Differences in chest dimensions can be related to functional differences in respiratory physiology, since the highland groups, both male and female, have larger forced expiratory volumes and forced vital capacities as compared with the lowlanders. The relationships between these measures of respiratory function and age, stature and weight also tend to be dependent on altitude, but in all the Ethiopian groups there is a closer relationship between body weight and respiratory capacity than in other populations. This distinctiveness is probably due to the characteristics of Ethiopian physique. A slight polycythaemia and elevated packed cell volume are evident in the highland groups but, unexpectedly, there is some evidence that at least at the time of the expedition the haemoglobin concentrations were lower. The highlanders also show a raised systolic blood pressure. Blood-group and demographic data suggest that the various populations are probably genetically very similar, and the findings are discussed in terms of physiological and developmental adaptability.

Preliminary investigations of a new beta-adrenoceptive receptor blocking drug, LB46, in man

Abstract: 1. Preliminary studies in man of a new beta-adrenoceptive receptor blocking drug, DL-4-(2-hydroxy-3-isopropylaminopropoxy)-indole (LB46), are described. 2. LB46, 0·5 mg by oral administration, appeared to be of similar potency to propranolol 20 mg in inhibiting isoprenaline-induced and exercise-induced tachycardia. 3. In comparable beta-receptor blocking doses LB46 did not show the negative chronotropic property possessed by propranolol.

The Effect of Noradrenaline on the Calcium Uptake of the Sarcoplasmic Reticulum

Abstract: It is known that noradrenaline has a profound effect on myocardial contractility, but no satisfactory explanation of this process at a cellular level has been available previously. In this paper evidence is presented that noradrenaline increases the rate of uptake of calcium by the sarcoplasmic reticulum. The experimental findings correlate well with the effects of noradrenaline on cardiac contraction, and a hypothesis is suggested which explains the positive inotropic effect of the drug.

The surface structure of mouse peritoneal cells—a study with the scanning electron microscope

Abstract: SUMMARY Normal and stimulated peritoneal cells have been examined with the Stereo-scan scanning electron microscope. Normal lymphocytes were identified by their small size; some had numerous small stubby or pointed processes on their surfaces. Macrophages were larger and had ridge-like processes. Many of the stimulated cells showed no significant deviation from normal. Others, all macrophages, showed a marked deviation from the normal spherical shape. Ridge-like processes were more prominent on their surfaces, and large flange-like processes and a few finger-like processes were seen. This suggests that on stimulation peritoneal cells become more deformable and therefore irregular in shape, and that their surfaces become rougher.

The Evaluation of an Ultrasonic Flow Detector for the Assessment of Peripheral Vascular Disease

Abstract: The circulation in the lower limbs of 50 patients with vascular disease was assessed transcutaneously with a commercially available ultrasonic flow detector. In 66 limbs, the results were compared with arteriograms. The findings were entirely correct in 57 limbs, and in every limb a reliable indication of the adequacy of the blood supply was obtained.

The excretion of amino acids by cystinuric patients and their relatives

Abstract: Dent & Harris (1951) differentiated classical cystinuria with increased excretion of lysine and arginine from other conditions in which the urinary excretion of cystine is increased as part of a generalized amino aciduria. Harris, Mittwoch, Robson & Warren (1955) studied the genetics of the disorder and proposed that the affected families should be classified as ‘recessive ’ or ‘ incompletely recessive ’, there being no detectable abnormality in the presumably heterozygous individuals in the former group whereas the heterozygous members of the ‘incompletely recessive ’ families have detectable abnormalities in their excretion of cystine and/or the basic amino acids. Harris & Robson (1955) also concluded on the basis of genetic evidence that recessive cystinuria includes more than one genetic entity but that incompletely recessive cystinuria is genetically homogeneous. Rosenberg ‘and his colleagues classified cystinuric patients into types I, I1 and I11 on the basis of the ability of the patients’ jejunal mucosa to transport isotopically labelled amino acids in witro (Rosenberg & Segal, 1965; Rosenberg, Durant & Holland, 1965; Rosenberg, Downing, Durant & Segal, 1966). Type I cases correspond to recessive cystinuria and types I1 and I11 are subgroups of incompletely recessive cystinuria. Studies of the renal clearance of amino acids have also demonstrated heterogeneity in the disease. Thus, some patients have cystine clearance values which are signikantly greater than the simultaneously measured glomerular filtration rate, whereas in other patients the cystine clearance and glomerular filtration rate are approximately equal (Crawhall, Scowen, Thompson & Watts, 1967). Heterogeneity could be due to cystinuria including more than one patho-physiological entity which available diagnostic methods are not sufficiently sensitive to separate. Alternatively the condition might be a single genetic entity and the apparent heterogeneity might be due to different degrees of expression of the single defect. Crawhall, Saunders & Thompson (1966) studied the amino acid excretion by a small number of cystine stone formers and their parents. They concluded that arginine excretion was increased in the subjects who were homozygous for the abnormal gene causing cystinuria, but not in the corresponding heterozygotes. They also suggested that an increased lysine excretion was sometimes the only feature which differentiates cystinuria heterozygotes from normal subjects. In the present work, the excretions of cystine and the basic amino acids have been studied in cystine stone formers, their parents and in normal subjects. The cystine stone formers are regarded as being homozygous and their parents as heterozygous for the cystinuria gene. The results obtained for these three groups of subjects are compared with one another and with those obtained for the other blood relatives of the stone formers in order to determine if the members of the latter group could be classified as cystinuria homozygotes, heterozygotes or normal on * Present address : Royal Victoria Hospital, McGill University, Montreal, Canada. t Address after 1st January 1970: Medical Research Council, Clinical Research Centre, Northwick Park,

The conversion of 4-hydroxypyrazolo-[3,4-d]pyrimidine (allopurinol) into 4,6-dihydroxypyrazolo[3,4-d]pyrimidine (oxipurinol) in vivo in the absence of xanthine–oxygen oxidoreductase

Abstract: 1. A patient with congenital deficiency of xanthine oxidase (EC 1.2.3.2) (xanthinuria) excreted the xanthine isomer 4,6-dihydroxypyrazolo[3,4-d]pyrimidine (oxipurinol) in his urine when the hypoxanthine isomer 4-hydroxypyrazolo[3,4-d]pyrimidine (allopurinol) was given by mouth. 2. The identity of the oxipurinol that the patient excreted was established by mass spectrometry. 3. The mass spectra and infrared spectra of allopurinol, oxipurinol, hypoxanthine and xanthine are compared. 4. A mechanism for the fragmentation of these compounds that occurs during their mass-spectrometric investigation is proposed. 5. A possible metabolic pathway for the oxidation of allopurinol to oxipurinol in the absence of xanthine oxidase is discussed.

New evidence for the existence of long lived macrophages.

Abstract: PROLONGED observation of labelled macrophages within inflammatory reactions in the ear chambers of rabbits has led to the suggestion that some of these cells may be very long lived1,2. Objective evidence in favour of the existence of long lived macrophages has, however, been lacking. In addition, study of granulomata induced by complete Freund adjuvant indicates a high rate of turnover of participating macrophages, with no evidence of persistence beyond 1–2 weeks of the mononuclear cells that originally emigrated into the lesion from the circulation3. We have found a similar high rate of turnover among the macrophages in chronic inflammatory reactions provoked by B. pertussis vaccine or paraffin oil.