Permeability of mitochondria to sucrose induced by hydrostatic pressure

When subjected to increasing pressure at 0 degree C, rat liver mitochondria become permeable to sucrose, causing them to swell and their outer membrane to rupture. Afterwards they are lysed and their matrix content is released into the medium. This permeation to sucrose may be prevented to some extent by increasing the temperature at which compression is carried out. 0.75 mM imipramine protects mitochondria against lysis caused by hydrostatic pressure, but does not oppose their permeation to sucrose nor the swelling resulting from the compression. At this concentration, the drug does not exhibit a significant effect on the lateral phase separations which take place in the inner mitochondrial membrane under pressure. The mitochondria of rat fetal liver (21 days), kidney and Morris hepatoma 16 become permeable to sucrose when they are subjected to compression; under these conditions, lateral phase separations occur in their inner membrane. Contrary to liver mitochondria, the former do not undergo lysis. Taking into account both present and previous results, events leading to mitochondrial membrane deterioration by hydrostatic pressure may be summarized in the following way. Pressure first leads to a phase transition of the membrane lipids, thus causing a permeation to sucrose; as a result the mitochondria swell because they have absorbed osmotic water. The membrane lipids freeze increasingly as the pressure increases; the inner membrane becomes fragile and finally, in the case of the adult liver organelles, can no longer resist the swelling. All these events can be avoided by increasing the temperature; imipramine only prevents inner membrane lysis.

Influence of immersion to the neck in water on airway closure and distribution of perfusion in man

We measured closing volume (CV), expiratory reserve volume (ERV) regional distribution of lung volume (Vr) and perfusion in 7 normal subjects in air and during immersion to the neck in water. In four subjects immersion resulted in a CV greater than ERV and the normal perfusion distribution became inverted. In the other subjects, ERV remained larger than CV and perfusion distribution during immersion was uniform, not inverted. In 5 subjects closing volume increased and in 3 of them, the ratio of apical/basal Vr increased significantly during immersion. One subject had nomeasurable CV and in the other it was not measured. The data suggest: (1) that when CV is greater than ERV during immersion there is an inversion of the normal perfusion distribution, caused by hypoxia and/or an increase in mean alveolar pressure in the alveoli beyond the closed airways, and (2) that an increase in pleural pressure gradient during immersion may contribute to the increase in C.V.

Comparison of sensitivity and specificity of counter electrophoresis, complement fixation and radioimmunoassay for detecting antibodies against hepatitis B core antigen

Sensitivity and specificity of anti-HBc detection by counter-immunoelectrophoresis (CEP), complement fixation (CF) and radioimmunoassay (RIA) tests were compared in sera from 69 patients with chronic hepatitis, 61 black African people suffering from primary hepatocellular carcinoma and 50 controls composed of French country people. CEP and CF tests gave the same results in detecting anti-HBc antibodies. The RIA test was found to be more sensitive and seems to be more specific than CEP and CF.

[Sub-umbilical laparotomy by supra-pubic disinsertion of the abdominal rectus muscles (Cherney's incision). 220 cases (author's transl)]

Used in pelvic surgery in women, supra-pubic disinsertion of the rectus muscles, combining a satisfactory aesthetic result, comfort and the possibility of enlargement, was associated with a minimum of complications (4 haematomas, 4 hernias and 2 cases of breakdown) and would be suitable as a routine approach in surgery of this type.

Isolation of rat liver lysosomes by isopycnic centrifugation in a metrizamide gradient

A preparation, similar to the light mitochondrial fraction of rat liver (L fraction of de Duve et al, (1955, Biochem. J. 60: 604-617), was subfractionated by isopycnic centrifugation in a metrizamide gradient and the distribution of several marker enzymes was established. The granules were layered at the top or bottom of the gradient. In both cases, as ascertained by the enzyme distributions, the lysosomes are well separated from the peroxisomes. A good separation from mitochondria is obtained only when the L fraction if set down underneath the gradient. Taking into account the analytical centrifugation results, a procedure was devised to purify lysosomes from several grams of liver by centrifugation of an L fraction in a discontinuous metrizamide gradient. By this method, a fraction containing 10--12% of the whole liver lysosomes can be prepared. As inferred from the relative specific activity of marker enzymes, it can be estimated that lysosomes are purified between 66 and 80 times in this fraction. As ascertained by plasma membrane marker enzyme activity, the main contaminant could be the plasma membrane components. However, cytochemical tests for 5'AMPase and for acid phosphatase suggest that a large part of the plasma membrane marker enzyme activity present in the purified lysosome preparation could be associated with the lysosomal membrane. The procedure for the isolation of rat liver lysosomes described in this paper is compared with the already existing methods.

[Pull-through procedure for carcinoma of the rectum. Results of 65 operations (author's transl)]

These sixty five cases of abdomino-trans anal excision account for approximately one third of 210 operations performed for carcinoma of the rectum. In the context of curative surgery, indications for preservation of the sphincter must be strict in order to permit satisfactory excision inferior to the tumour and to avoid the risk of local recurrence. Post-operative care and early complications involve the segment of colon which must be brought down. Gangrene of the exteriorised colon did not, in general, compromise the definitive result, at the price of an early colostomy which could always be closed later. Long term results are encouraging: 22 patients out of 26 who underwent non-palliative surgery are alive, without recurrence, after 5 years. The functional result can be assessed only after 6 months adaptation. One patient in two considers himself to be normal. The other half are forced to used enemas, and one in four must wear a protective dressing.

Lateral phase separations and structural integrity of the inner membrane of rat-liver mitochondria. Effect of compression. Implications in the centrifugation of these organelles

When maintained in the vicinity of the lower transition temperature of their membrane lipids, rat-liver mitochondria undergo lysis as shown by the release of malate dehydrogenase, (an enzyme located within the mitochondrial matrix), in the surrounding medium. Structural changes take place in the membranes of mitochondria subjected to increasing pressure at 0 degrees C, when the pressure reaches 750 kg/cm2. Freeze-fracture electron microscopy shows the appearance of smooth areas devoid of particles in fracture faces of mitochondrial membranes, together with zones, where aggregated particles can be seen. Concurrently, a suppression of the malate dehydrogenase structure-linked latency is observed. These structural changes can be prevented by increasing the temperature at which compression is performed. The freeze-etching observations suggest that lateral phase separations occur in mitochondrial membranes subjected to high pressure. This can be explained by supposing that pressure promotes the gel-phase appearance in a lipid system and raises the transition temperature since the transition liquid crystal lead to gel is accompanied by a decrease in volume. The deterioration of mitochondria subjected to high pressure is interpreted as a result of the lateral phase separation induced by compression in the membranes. These results are discussed with respect to our interpretation of the damaging effects that hydrostatic pressure, generated by centrifugation, exerts on rat-liver mitochondria.

Relationship between viscoelastic properties of the rectum and anal pressure in man

Viscoelastic properties of the rectal wall and anal sphincter pressure were studied simultaneously in 25 normal children. During rectal distension for 60 s, with varying volumes of air, the rectal pressure varied as the sum of two exponential functions of the time plus an asymptotic constant. A rectoanal inhibitory reflex was elicited during these distensions. The exponential decrease of the rectal pressure corresponded exactly to the return of the upper anal canal pressure to the resting value in some subjects. In others, the upper anal canal remained relaxed as long as the rectal ampulla was distended, except with smaller volumes. The results obtained may be explained by an analogical rheological linear model.

Manometric assessment of continence after surgery for imperforate anus

Of 49 children with imperforate anus, 23 underwent an abdominoperineal procedure for a high and seven for a low maliformation, 17 had a perineoplasty for a low and two for a high malformation. In each subject, rectal and anal sphincteric resting pressures were studied at least 1 yr after surgery. Of 30 subjects who had undergone an abdominoperineal procedure, eight were continent in contrast to 15 out of 19 patients who had had a perineoplasty (p less than 0.001). In patients who had undergone an abdominoperineal procedure, the rectal motility was of the colonic type, with waves of higher amplitude and lower frequency (p less than 0.01) than in the normal rectum in 23 cases and in most of these, peristalsis was recorded down to the anal margin. Incontinence was most frequently associated with abnormally short anal resistance, low anal pressure, reduced sensibility, weak voluntary contraction and absence of rectoanal inhibitory reflex. In the group of patients who underwent perineoplasty, continence was associated with normal mechanical parameters and normal physiologic behavior of the anal sphincter.

[Study of prostaglandin synthesis during anaphylactic shock in guinea pigs]

In guinea pigs actively sensitized with ovalbumin and shocked, we have measured blood histamine and histaminase, pulmonary content in cycli AMP and prostaglandins (PG) E1, E2 and F2alpha. In pulmonary efferent blood, both PGE and PGF are increased. In lung tissue, only PGF2alpha, which are bronchoconstructive mediators, are increased. Th increased level in PG seems to have two origins: first a specific increase, then an increased synthesis secondary to histamine release.