The effects of secretagogues on the incorporation of (2- 3 H)myoinositol into lipid in cytological fractions in the pancreas of the guinea pig in vivo

Stimulation of enzyme secretion in the pancreas on injection of a single dose of the cholinergic drug, pilocarpine, was associated with an increased incorporation of [2-(3)H]myoinositol into a lipid, which was previously characterized as phosphatidylinositol. Stimulation of enzyme secretion by hourly injection of the pancreozymin congener, caerulein, led to more increased phosphatidylinositol synthesis than with a single injection of pilocarpine. The amylase level of the pancreas remained at a low level as long as caerulein was injected, indicating continued stimulation of enzyme secretion even though increased phosphatidylinositol synthesis ceased after 6 h. Feeding gave the same stimulation of phosphatidylinositol synthesis as caerulein. The major synthesis of phosphatidylinositol in controls and the stimulation of phosphatidylinositol synthesis by pilocarpine was entirely confined to the microsome fraction throughout the experiments (up to 18 h). This shows that there is no flow of microsomal membrane (smooth- or rough-surfaced endoplasmic reticulum) to other membranous structures throughout the secretory cycle and beyond. It is concluded that the stimulation of phosphatidylinositol synthesis by pancreatic secretagogues is confined to microsomal elements and does not play any role in membrane flow.

Abdominal actinomycosis

A case of sigmoid actinomycosis is described and the cases of abdominal actinomycosis presenting at the Manchester Royal Infirmary over the past 20 years are reviewed. The whole problem of abdominal actinomycosis is discussed, with special reference to the sites of infection and mode of treatment. The relevant literature is reviewed.

Adjuvant activity of Mycobacterium leprae

Mycobacterium leprae organisms isolated from infected spleen and liver tissue by zonal centrifugation were shown to possess adjuvant activity. Histochemical examination of the footpad macrophage epithelioid granuloma showed that macrophages contained large amounts of hemosiderin after the injection of M. leprae and much smaller amounts after the injection of M. tuberculosis.

Digestion of an exogenous protein by rat yolk-sac cultured in vitro

Yolk-sacs were removed from 17.5-day pregnant rats injected 2-5h previously with (125)I-labelled bovine serum albumin. The specific activities of acid phosphatase and acid proteinase, and the specific radioactivities (trichloroacetic acid-insoluble and trichloroacetic acid-soluble) were measured in subcellular fractions prepared by homogenization and differential centrifugation. The conversion of acid-insoluble into acid-soluble radioactivity within cultured tissue was followed and the nature of the liberated products was investigated by gel chromatography. The results are consistent with the protein entering lysosomes and being digested there. The radiolabel was released chiefly as free iodotyrosine.

The effect of Trypan Blue, suramin and aurothiomalate on the breakdown of 125 I-labelled albumin within rat liver lysosomes

1. A fraction enriched in lysosomes was prepared by centrifugation from the livers of rats that had been injected 0.5h before death with (125)I-labelled albumin. When suspended in sucrose-protected buffer, pH7.4, and incubated at 22 degrees C for 2h, the particles progressively released iodotyrosine into the medium. Albumin digestion did not occur if the particles were subjected to treatments known to break lysosomes or if particles from uninjected rats were incubated in medium containing (125)I-labelled albumin. It is concluded that the observed production of iodotyrosine results from protein hydrolysis within intact heterolysosomes. 2. Particles from rats pre-treated with Trypan Blue, suramin or aurothiomalate released iodotyrosine more slowly than controls. Since these compounds are enzyme inhibitors that concentrate in liver lysosomes after administration in vivo, their effect is ascribed to intralysosomal inhibition of proteolysis. The doses used did not decrease endocytosis of albumin into liver or cause increased lysosome breakage during incubation, thus allowing some alternative explanations of the decreased proteolysis to be eliminated. Particulate carbon, a non-inhibitor that also concentrates in lysosomes, did not affect albumin hydrolysis.

Potassium-dependant mutants of Escherichia coli K-12

Mutants of Escherichia coli K-12 that grow more slowly in media containing low concentrations of K have been isolated. All independent mutants of this type which have been studied carry a mutation in a small region of the bacterial chromosome between the supE and gal loci. The growth rate of the mutants is the same as that of the parental strains in medium containing more than 1 mm K, but is only 50% that of the parent when the K concentration is reduced to 0.1 mm. The mutants do not appear to have a primary alteration in K transport, and are therefore referred to as K-dependent. The abbreviation kdp is proposed for this class of mutant.

Protein digestion in isolated lysosomes inhibited by intralysosomal trypan blue

Control rats and rats treated with subcutaneous trypan blue were injected intravenously with denatured albumin-I(125). Lysosome-rich fractions of their livers, when incubated at 22 degrees C in osmotically protected medium (pH 7.4), retained their capacit to digest albumin-I(125). The rate of digestion was lower in suspensions pre-pared from rats treated with trypan blue than in control suspensions, but rates of lysosome breakage were not different. T'hese results and other experimental evidence suggest that trypanblue concentrated within lysosomes can inhibit intralysosomal digestion, probably by inhibition of lysosomal proteinases.

Aetiology of chronic heart block. A clinico-pathological correlation in 65 cases

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Pathological basis of primary heart block

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The conduction system in acute myocardial infarction complicated by heart block

Detailed histological examination of the conduction system in 29 cases of acute myocardial infarction complicated by heart block has been carried out. In 24 cases posterior infarction was present and occlusion had occurred in the artery from which the blood supply to the A-V node was ultimately derived. In these cases major structural damage to the conduction system was rare, but when present, involved the bundle branches. A-V block in posterior infarction is therefore usually due to hypoxia or other reversible factors rather than structural damage to the conduction system. These findings are consistent with the high incidence of transient heart block in survivors.

In five cases anterior infarction alone was present. The blood supply of the A-V node was not compromised, but massive infarction had caused major damage to both bundle branches.

Since major structural damage to the conduction system is uncommon in myocardial infarction, only a minority of survivors will have permanent heart block. In those cases in which there is extensive damage to the bundle branches there is a risk of high mortality and permanent block particularly when the infarct is anteroseptal.

Primary hyperparathyroidism presenting as spinal cord compression

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The glycosulphatase of Trichoderma viride

The growth of the mould Trichoderma viride on a defined medium containing either potassium d-glucose 6-O-sulphate or potassium d-galactose 6-O-sulphate as sole sources of both carbon and sulphur is marked by the production of an enzyme system capable of liberating inorganic SO(4) (2-) ions from either of the sulphate esters. The enzyme is not produced when the organism is grown with glucose (or galactose) and potassium sulphate or with glucose and methionine as sole sources of carbon and sulphur. Experimental conditions are described whereby inorganic SO(4) (2-) ions liberated from potassium glucose 6-O-sulphate by the growing mould appear in the culture medium after a constant lag period of 21-24hr. The enzyme has been shown to be a simple glycosulphatase that is active towards the 6-O-sulphate esters of d-glucose and d-galactose but not towards potassium glucose 3-O-sulphate. The properties of the crude glycosulphatase show the enzyme to be appreciably different from analogous molluscan enzymes that can degrade monosaccharide sulphate esters.

Sibs with mental and physical retardation and trichorrhexis nodosa with abnormal amino acid composition of the hair

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Osmotic volume flow in the proximal tubule of Necturus kidney

Volume changes due to osmotic flow in the distal portion of proximal tubules of Necturi were measured by the split oil drop technique. In agreement with previous findings no volume flow was induced by NaCl concentrations close to 60 mM. The tubule wall was found to be permeable to plasma electrolytes, which have an apparent reflection coefficient of 0.69. The mean apparent hydraulic conductivity was 0.33 x 10(-11) cm(3)/dyne sec, comparable with other epithelia. A number of lipid-insoluble nonelectrolytes of widely varying molecular size had apparent reflection coefficients of about 0.5. In view of the insensitivity to molecular size it seems likely that apparent reflection coefficients determined from tubular volume changes depend primarily on the porosity of the intercellular barrier closest to the lumen and give little information about the subsequent fate of the test substances.

Causes of death in patients with complete heart block and aritificial pacemakers

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Thermal migration in biological transport?

It is shown by thermodynamic arguments and by semiquantitative considerations that the contribution of thermal migration to biological transport is likely to be small.

The composition and physicochemical properties of hyaluronic acids prepared from ox synovial fluid and from a case of mesothelioma

1. Materials containing hyaluronic acid have been prepared by filtration (Ogston & Stanier, 1950) from ox synovial fluid and from a protein-rich human mesothelioma fluid. The ox material has been deproteinized by treatment with chloroform and pentanol and by gradient elution on DEAE-Sephadex; several fractions were obtained by the latter method. These materials can be stored in solution at -20 degrees without change of properties. The ox material contained 21% of protein; all other preparations contained less than 6% of protein. 2. The two materials have been compared by sedimentation and viscosity and shown to be closely similar. Treatment of the ox material with neuraminidase caused no change in its viscosity behaviour. 3. Information about the molecular configuration of the ox material has been obtained from measurements of light-scattering and viscosity. The results, though consistent with a highly extended configuration, are not consistent with a linear random-coil configuration. It is tentatively suggested that the structure may have some degree of branching and of cross-linking, which give it a rigidity with respect to expansion of the molecular domain that would not be possessed by a random coil. 4. The deproteinized material recovered from DEAE-Sephadex, though polydisperse, showed unchanged average molecular weight; however, the average radius of gyration was greater than before this treatment. 5. Acidification to approx. pH3 resulted in a contraction of the structure, with only a slight degree of expansion when the pH was restored to 6.8-7.0. 6. Measurements of optical rotatory dispersion qualitatively support a structure less simple than a linear random coil. 7. Colloid osmotic pressures of mixed solutions of bovine serum albumin and of hyaluronic acid prepared by filtration from ox synovial fluid have been measured. The results agree approximately with those of Laurent & Ogston (1963) but are in quantitative disagreement with the partition measurements of Ogston & Phelps (1960). The relationships between thermodynamic quantities in a quaternary system of electrolytes are discussed in Appendix 2. 8. Refractometric measurements have been made in connexion with light-scattering measurements, as the basis for a convenient method of determining the concentrations of solutions of hyaluronic acids, and to measure the partition of sodium chloride in dialysis experiments. The theory of the last use is discussed in Appendix 1. 9. Sedimentation measurements on the ox preparation have been made up to a concentration of 1.4x10(-2)g./ml. The form of the sedimentation coefficient-concentration relationship is discussed. The value of the sedimentation coefficient at higher concentration is the basis of an illustration of the likely effect of hyaluronic acid on the flow of water through narrow channels in connective tissue. 10. Available colorimetric methods have been shown to give low estimates for glucuronic acid when applied to highly polymerized materials, as compared with estimates by decarboxylation. A spectrophotometric titration with cetylpyridinium bromide has been shown to give estimates of carboxyl groups that agree well with those of decarboxylation when applied to preparations of hyaluronic acid under suitable conditions; the results are not affected by the presence of protein. 11. Estimates of glucosamine (Ogston, 1964) have been found to be low compared with those of total acetyl, independently of the presence of protein. The magnitude of the discrepancy is characteristically different for preparations from ox synovial fluid and from mesothelioma. 12. Sialic acid was estimated in several preparations. It is likely that this forms part of the protein. 13. Analyses of preparations for total nitrogen, amino acids, total acetyl, glucuronic acid (by decarboxylation) and ash account for at least 95.7% of the dry weight in terms of N-acetylglucosaminyl, glucuronyl, protein and metal ions. Previously published analyses of hyaluronic acids are reviewed. 14. The estimated molar ratios of glucuronic acid to glucosamine were all significantly greater than unity. 15. The analytical results are interpreted as agreeing with the physicochemical measurements in suggesting a more complex structure, for at least some hyaluronic acids, than that of an alternate linear copolymer in random-coil configuration.