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Biomedical subjects

J Carlsson

Publications and source records attributed to J Carlsson.

At least 325 records · Page 18Linked to original sources
PubMed1977

Superoxide dismutase in Bacteroides fragilis and related Bacteroides species.

Superoxide dismutase (SOD) activity was demonstrated in cell-free extracts of Bacteroides fragilis, Bacteroides vulgatus, Bacteroides distasonis, Bacteroides ovatus, and Bacteroides thetaiotaomicron. The strains were grown under anaerobic conditions in Trypticase soy broth, and the specific activity of SOD in the extracts was, in most strains, higher than in cell-free extracts of Escherichia coli B grown under anaerobic conditions. Isoelectric focusing of the extracts in polyacrylamide gel demonstrated distinct forms of SOD in the different species.

Anaerobiosis↗
PubMed1977

Oxygen tolerance of anaerobic bacteria isolated from necrotic dental pulps.

The oxygen tolerance of 43 anaerobic reference strains and 36 anaerobic strains from necrotic dental pulps was studied. All strains survived for two hours or more as colonies on the surface of a medium supplemented with blood, and as many as 26 of the 79 strains survived for more than seven days. The hemolysed blood in the medium significantly increased the survival time for many of the strains. Factors influencing the death rate were studied in one of the strains and it was found that the lysed red cells of the blood and not the serum had a protective effect and that catalase had the same protective effect as the hemolysed blood. The finding that hemolysed blood significantly increased the oxygen tolerance of many anaerobes may explain some of the divergent results regarding the efficiency of various methods for the recovery of anaerobic bacteria from clinical specimens. The use of media supplemented with blood during various phases of processing a specimen might be more important for a high recovery of anaerobic bacteria from clinical sources than the measures taken to minimize exposure of the specimen to air.

Bacteriological Techniques↗
PubMed1976

The measurement of spatial precursor distributions in cell culture.

The distribution of incorporated radioactive precursors, for both DNA and protein synthesis, has been measured with a resolution of about 1 mm in cell cultures, using a scanning technique. Either gamma radiation and X-rays or beta radiation (electrons) were detected by scintillation detectors. Spectrophotometer measurements with a resolution of 1 mm gave good estimates of cell density changes. Glioma cell colonies were used to compare this technique with autoradiography. Variables such as the density of labelled cells and percentage of labelled cells could be estimated rather accurately. For example, an increased cell density was correlated to a local decrease in DNA synthesis.

Cell Count↗
PubMed1975

Reversible, covalent immobilization of enzymes by thiol-disulphide interchange.

1. alpha-Amylase and alpha-chymotrypsin have been immobilized by covalent attachment to mercaptohydroxypropyl ether agarose gel. The technique involves two steps: (a) thiolation of the enzymes by methyl 3-mercaptopropioimidate, (b) coupling of the thiolated enzymes to a mixed disulphide derivative of agarose obtained by reacting mercaptohydroxypropyl ether agarose with 2,2'-dipyridyl disulphide. 2. The immobilization technique can be performed so that most of the inherent activity of the enzymes is conserved. However, diffusion limitations and steric factors prevent full manifestation of the immobilized activities. 3. Immobilized alpha-amylase was used in a packed-bed reactor for the continuous hydrolysis of starch. When the enzymically active gel had lost its activity it could be regenerated in situ by reductive uncoupling of the inactive protein and attachment of a new portion of thiolated alpha-amylase.

Amylases↗
PubMed1975

The thiol group of bovine serum albumin. High reactivity at acidic pH as measured by the reaction with 2,2'-dipyridyl disulphide.

The reaction between 2,2'-dipyridyl disulphide and the thiol group in bovine serum albumin has been studied at pH 1.1-7.9. At pH 5.5-7.9 the reaction rate was second order in dipyridyl disulphide and thiolate ion, as expected for an aliphatic thiol compound. Below pH 5.5 the reaction rate increased and became maximum at pH 2.6. The observed rate constant (110 M-1-s-1) was comparable with that at pH 6.6, although the thiolate ion concentration should be 10(4) times less at the lower pH. The increase in reactivity seemed to be correlated with the conformational change in serum albumin at pH 3.6-4.0. Increased nucleophilicity due to interaction with some suitable functional group might explain the high reactivity of the SH group at acidic pH.

2,2'-Dipyridyl↗
PubMed1975

A rapid and specific method for isolation of thiol-containing peptides from large proteins by thiol-disulfide exchange on a solid support.

Activated thiol-Sepharose [agarose-(glutathione-2-pyridyl disulfide) conjugate] has been used to immobilize proteins with a single or a few thiol groups via disulfide bridges. The immobilized proteins were subsequently proteolytically degraded. After washing, the thiol-containing peptides were eluted with a reducing agent. A single preparative paper electrophoresis, occasionally after a modification such as oxidation, was sufficient to obtain pure peptides in good yields. The method was applied to the major parvalbumin from hake muscle (a protein with 108 amino acid residues and one cysteine residue), to mercaptalbumin from bovine serum (565 residues and one cysteine), and to human serum ferroxidase [EC 1.16.3.1; iron (II):oxygen oxidoreductase] (ceruloplasmin) (1065 residues and three cysteines). The use of the technique, e.g., as a simple means of obtaining homologous peptides in related proteins, is discussed.

Albumins↗
PubMed1975

Respiratory insufficiency syndrome (RIS) in preterm infants with gestational age of 32 weeks and less. Neonatal management and follow-up study.

The clinical entity of respiratory insufficiency syndrome (RIS), i.e. irregular breathing leading to recurrent apnea and bradycardia in an otherwise healthy preterm infant, has been studied in respect of symptomathology and management with intensive case including ventilatory support. During a 4-year period 26 of 103 infants with gestational age less than or equal to 32 weeks and mean weight 1304 g (range 710 to 1830 g) developed RIS. In most infants the initial apnea occurred after 2 and before 72 hours post delivery but in some infants later. Because of progressive hypoxemia and acidosis 15 of the 26 RIS infants required IPPV treatment. The 76% survival rate of RIS infants seems to justify intensive care with ventilatory support even in the smallest preterm infants with RIS, especially as the follow-up study performed at 15 months to 3-1/2 years of age showed neurological sequelae in only 3 of 20 surviving babies, i.e. 15% sequelae rate.

Apnea↗
PubMed1975

Regulation of lactate dehydrogenase and change of fermentation products in streptococci.

Streptococcus mutans JC 2 produced mainly lactate as a fermentation product when grown in nitrogen-limited continuous culture in the presence of an excess of glucose and produced formate, acetate, and ethanol, but no lactate, under glucose-limited conditions. The levels of lactate dehydrogenase (LDH) in these cultures were of the same order of magnitude, and the activity of LDH was completely dependent on fructose-1,6-diphosphate (FDP). The intracellular level of FDP was high and the level of phosphoenolpyruvate (PEP) was low under the glucose-excess conditions. In the glucose-limited cultures, all glycolytic intermediates studied, except PEP, were low. S. mutans FIL, which had an FDP-independent LDH and similar levels of glycolytic intermediates as S. mutans JC2, produced mainly lactate under glucose-excess or under glucose-limited conditions. LDH of Streptococcus bovis ATCC 9809 was dependent on FDP for activity at a low concentration of pyruvate but had a significant activity without FDP at a high concentration of pyruvate. This strain also produced mainly lactate both under glucose-excess and glucose-limited conditions. The levels and characteristics of these LDHs were not changed by the culture conditions. These results indicate that changes in the intracellular level of FDP regulate LDH activity, which in turn influences the type of fermentation products produced by streptococci. PEP, adenosine 5'-monophosphate, adenosine 5'-diphosphate, and inorganic phosphate significantly inhibited LDH activity from S. mutans JC 2 and may also participate in the regulation of LDH activity in other streptococci.

Acetates↗
PubMed1975

Glucose-6-phosphate-dependent pyruvate kinase in Streptococcus mutans.

Pyruvate kinase of Streptococcus mutans JC 2 had an absolute and specific requirement for glucose-6-phosphate. Inorganic phosphate was a strong inhibitor. The enzyme required K+ or NH4+ and Mg2+ or Mn2+. S. mutans FIL and E 49, Streptococcus bovis ATCC 9809, and Streptococcus salivarius ATCC 13419 had also glucose-6-phosphate-dependent pyruvate kinases, whereas Streptococcus sanguis NCTC 10904 had an enzyme activated by fructose-1,6-diphosphate.

Ammonia↗
PubMed1975

Transmission of Lactobacillus jensenii and Lactobacillus acidophilus from mother to child at time of delivery.

The presence of Lactobacillus jensenii and Lactobacillus acidophilus has been studied in specimens from the rectum and vagina of the mother, from the mouth of the infant at the time of delivery, and from the mouth and rectum of infants six days of age. L. jensenii could be differentiated from other species of lactobacilli by the following combination of characteristics: production of only D-lactate, hydrolysis of arginine, and fermentation of cellobiose, galactose, and ribose, but not of lactose. L. jensenii and L. acidophilus were common inhabitants of the vagina. In spite of a contamination of the infant's mouth by L. jensenii and L. acidophilus during delivery, neither of these organisms became established in the mouth of the newborn infants.

Adult↗
PubMed1974

Reactions of L-ergothioneine and some other aminothiones with2,2'-and 4,4'-dipyridyl disulphides and of L-ergothioneine with iodoacetamide. 2-Mercaptoimidazoles, 2- and 4-thiopyridones, thiourea and thioacetamide as highly reactive neutral sulphur nucleophils.

1. The reactions of 2,2'- and 4,4'-dipyridyl disulphide (2-Py-S-S-2-Py and 4-Py-S-S-4-Py) with l-ergothioneine (2-mercapto-l-histidine betaine), 2-mercaptoimidazole, 1-methyl-2-mercaptoimidazole, thiourea, thioacetamide, 2-thiopyridone (Py-2-SH) and 4-thiopyridone (Py-4-SH) were investigated spectrophotometrically in the pH range approx. 1-9. 2. These reactions involve two sequential reversible thiol-disulphide interchanges. 3. The reaction of l-ergothioneine with 2-Py-S-S-2-Py and/or with the l-ergothioneine-Py-2-SH mixed disulphide, both of which provide Py-2-SH, is characterized by at least three reactive protonic states. This provides definitive evidence that neutral l-ergothioneine is a reactive nucleophile, particularly towards the highly electrophilic protonated disulphides. 4. A similar situation appears to obtain in the reactions of l-ergothioneine and Py-2-SH with 4-Py-S-S-4-Py and in the reactions of the other 2-mercaptoimidazoles, thiourea and Py-4-SH with 2-Py-S-S-2-Py. The nucleophilic reactivity of Py-4-SH suggests that general base catalysis provided by the disulphide in a cyclic or quasi-cyclic transition state is not necessary to generate nucleophilic reactivity in the other amino-thiones whose geometry could permit such catalysis. 5. The existence of a positive deuterium isotope effect in the l-ergothioneine-2-Py-S-S-2-Py system at pH6-7 provides no evidence for general base catalysis but is in accord with a mechanism involving specific acid catalysis and post-transition-state proton transfer. 6. The pH-dependences of the overall equilibrium positions of the various thiol-disulphide interchanges are described. 7. Reaction of thioacetamide with a stoicheiometric quantity of 2-Py-S-S-2-Py at pH1 provides 2 molecules of Py-2-SH per molecule of thioacetamide and elemental sulphur; these findings can be accounted for by thiol-disulphide interchange to provide a thioacetamide-Py-2-SH mixed disulphide followed by fragmentation to provide CH(3)CN, S and Py-2-SH. 8. Provision of high reactivity in the neutral forms of the members of this series of sulphur nucleophiles by electron donation by the amino group is compared with the well known alpha effect that provides enhanced nucleophilicity in compounds containing an electronegative atom adjacent to the nucleophilic atom. 9. The decrease in the u.v. absorption of l-ergothioneine at 257nm consequent on transformation of its aminothione moiety into an S-alkyl-2-mercaptoimidazole moiety provides a convenient method of following the alkylation of l-ergothioneine by iodoacetamide. 10. The pH dependence of the extinction coefficient of l-ergothioneine at 257nm is described by epsilon(257)={8x10(3)/(1+K(a)/[H(+)]} +6x10(3)m(-1).cm(-1) in which pK(a)=10.8. 11. In the pH range 3-11 the reaction is characterized by two reactive protonic states (X and XH). 12. The X state, reaction of the ionized 2-mercaptoimidazole moiety of the l-ergothioneine dianion with neutral iodoacetamide, is characterized by the second-order rate constant 4.0m(-1).s(-1) (25.0 degrees C, I=0.05). The XH state, characterized by the second-order rate constant 0.03m(-1).s(-1), is interpreted as reaction of the thione form of the neutral 2-mercaptoimidazole moiety of the l-ergothioneine monoanion with neutral iodoacetamide. 13. The XH state of the alkylation reaction does not exhibit a deuterium isotope effect.

2,2'-Dipyridyl↗
PubMed1974

A convenient spectrophotometric assay for the determination of L-ergothioneine in blood.

1. A convenient spectrophotometric assay for the determination of l-ergothioneine in solution including deproteinized blood haemolysate was developed. 2. The method consists of deproteinization by heat precipitation and Cu(2+)-catalysed oxidation of thiols such as glutathione and of l-ascorbic acid, both in alkaline media, and titration of l-ergothioneine (which is not oxidized under these conditions) by its virtually instantaneous reaction with 2,2'-dipyridyl disulphide at pH1. 3. This method and the results obtained with it for the analysis of human, horse, sheep and pig blood are compared with existing methods of l-ergothioneine analysis and the results obtained thereby.

Animals↗