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Biomedical subjects

J Thompson

Publications and source records attributed to J Thompson.

At least 721 records · Page 40Linked to original sources
PubMed1980

Self-help groups in a premature nursery-a controlled evaluation.

This study examined the effect discussion groups, held in a neonatal intensive care unit with parents of very small premature infants, had on various measures of later parenting competence. Twenth-eight families who met for seven to ten weeks with a nurse co-ordinator and a "veteran mother" who had given birth to a premature infant within the past year were compared with 29 control families. Parents who had participated in the groups visited their infants significantly more often in hospital than did the control parents. They also touched, talked, and looked at their infants in the en face position more during their visits, and rated themselves as more competent on a number of infant care measures. Three months after discharge of the infants, group mothers continued to show more involvement with their babies during feedings and were more concerned about their general development. The implications of such self-help groups for the later development of high-risk premature infants is discussed.

Adult↗
PubMed1980

Differing virulence of H1N1 and H3N2 influenza strains.

Sequential influenza A/Texas/77 (H3N2) and A/USSR/77 (H1N1) epidemics occurred during the winter of 1977-1978 in two populations under viral surveillance for influenza. In college students who reported to the Vanderbilt student health service, roughly equivalent amounts of typical influenzal disease were documented by virus isolation and total health service visits with both strains. However, considering that the college population was fully susceptible to the first introduction of H1N1 virus in 20 years and partially immune to H3N2 viruses through repeated exposure, A/USSR appeared to be a relatively less pathogenic strain. Stronger proof of this was seen in a closely monitored group of 200 largely seronegative infants and young children less than 4 years of age enrolled in an experimental vaccine clinic. In this young population, A/USSR caused no recognizable illness and A/Texas caused typical febrile respiratory disease. Thus, two influenza strains circulating in close temporal association differed in virulence when observed in carefully monitored susceptible populations.

Adolescent↗
PubMed1980

Effects of immunization and anticoagulation on the development of experimental Escherichia coli endocarditis.

The effects of immunization and anticoagulation in experimental Escherichia coli endocarditis were studied. Immunization of rabbits with E. coli resulted in the development of specific agglutinating and opsonic activity of the serum, but not in bactericidal activity. These antibody activities also developed in nonimmunized rabbits during the course of bactericidal endocarditis. Immune serum promoted phagocytosis in vitro but did not enhance intracellular killing of E. coli by elicited rabbit peritoneal macrophages. The presence of specific antibodies in rabbits after immunization had no effect on the induction or course of E. coli infection of endocardial vegetations. Anticoagulation was found to affect the induction of the infection. In anticoagulated rabbits, larger bacterial inocula were needed to induce an infection, but in animals with bacterial endocarditis the number of bacteria in the vegetations did not differ significantly from that of the control animals.

Agglutination↗
PubMed1980

Resistance to thiostrepton, siomycin, and sporangiomycin in actinomycetes that produce them.

The antibiotics thiostrepton, siomycin, and sporangiomycin are closely related both in structure and in mode of action. Actinomycetes which produce this group of compounds possess ribonucleic acid-pentose methylases, which act upon 23S ribosomal ribonucleic acid and render ribosomes resistant to the action of these antibiotics. This is achieved via the formation of a single residue of 2'-O-methyladenosine per ribosome.

Actinomycetales↗
PubMed1980

Galactose transport systems in Streptococcus lactis.

Galactose-grown cells of Streptococcus lactis ML3 have the capacity to transport the growth sugar by two separate systems: (i) the phosphoenolpyruvate-dependent phosphotransferase system and (ii) an adenosine 5'-triphosphate-energized permease system. Proton-conducting uncouplers (tetrachlorosalicylanilide and carbonyl cyanide-m-chlorophenyl hydrazone) inhibited galactose uptake by the permease system, but had no effect on phosphotransferase activity. Inhibition and efflux experiments conducted using beta-galactoside analogs showed that the galactose permease had a high affinity for galactose, methyl-beta-D-thiogalactopyranoside, and methyl-beta-D-galactopyranoside, but possessed little or no affinity for glucose and lactose. The spatial configurations of hydroxyl groups at C-2, C-4, and C-6 were structurally important in facilitating interaction between the carrier and the sugar analog. Iodoacetate had no inhibitory effect on accumulation of galactose, methyl-beta-D-thiogalactopyranoside, or lactose via the phosphotransferase system. However, after exposure of the cells to p-chloromercuribenzoate, phosphoenolpyruvate-dependent uptake of lactose and methyl-beta-D-thiogalactopyranoside were reduced by 75 and 100%, respectively, whereas galactose phosphotransferase activity remained unchanged. The independent kinetic analysis of each transport system was achieved by the selective generation of the appropriate energy source (adenosine 5'-triphosphate or phosphoenolpyruvate) in vivo. The maximum rates of galactose transport by the two systems were similar, but the permease system exhibited a 10-fold greater affinity for sugar than did the phosphotransferase system.

Adenosine Triphosphate↗
PubMed1980

Effects of monocytopenia and anticoagulation in experimental Streptococcus sanguis endocarditis.

The role of blood monocytes in the attachment of streptococci to endocardial vegetations was investigated in an experimental Streptococcus sanguis endocarditis by depletion of blood monocytes with the cytostatic drug VP 16-213 alone and combined with anticoagulant treatment with warfarin sodium. The numbers of streptococci in the vegetations of control, monocytopenic, and monocytopenic/anticoagulated rabbits were comparable. In the vegetations streptococci were found mainly in areas free of phagocytic cells. It is concluded that streptococci do not have to be phagocytosed by monocytes in the circulation before being deposited on the surface of endocardial vegetations. Even the vegetations of intensively anticoagulated/monocytopenic rabbits showed colonies of streptococci embedded in polymerized fibrin and cellular material, this matrix possibly being held together by streptococcal dextran.

Animals↗
PubMed1980

Experimental Streptococcus sanguis endocarditis: immune complexes and renal involvement.

An increase of agglutinins and circulating immune complexes (CIC) was observed in the sera of rabbits after the induction of bacterial endocarditis (BE) by intravenous injection of live streptococci into animals with a non-bacterial thrombotic endocarditis. Rabbits immunized for 12 days with heat-killed streptococci developed higher levels of agglutinins and CIC than did those unimmunized during BE. The levels remained elevated in the immunized rabbits after the induction of streptococcal endocarditis. In rabbits with very high levels of CIC complement activation occurred in vivo, possibly via the classical pathway. Kidneys from both unimmunized and immunized rabbits with streptococcal endocarditis contained bacteria and also showed inflammatory reactions but only the renal tissue of immunized rabbits with endocarditis showed a little mesangial deposition of immunoglobulin. The findings in this study indicate that in rabbits, renal inflammation due to BE is initiated more often by septic emboli than by immune complex deposition, at least during the first 12 days after infection.

Agglutinins↗
PubMed1979

Binding of thiostrepton to a complex of 23-S rRNA with ribosomal protein L11.

Thiostrepton binds with high affinity and with a 1 : 1 stoichiometry to a complex formed between Escherichia coli 23-S ribosomal RNA and ribosomal protein L11 of E. coli or the homologous protein BM-L11 of Bacillus megaterium. In the presence of T1 ribonuclease, protein BM-L11 and thiostrepton protect from degradation a fragment of E. coli 23-S RNA estimated to be about 50 nucleotides in length.

Anti-Bacterial Agents↗
PubMed1979

Enhancement of generation of monocyte tissue thromboplastin by bacterial phagocytosis: possible pathway for fibrin formation on infected vegetations in bacterial endocarditis.

The deposition of fibrin on infected vegetations and the presence of mononuclear phagocytes that have phagocytized bacteria are remarkabe features in experimental bacterial endocarditis. In a study in vitro, we show that phagocytosis of bacteria by human monocytes enhances thromboplastin generation by these cells. Maximal enhancement of the generation of thromboplastin by monocytes was about six times compared with that in the control experiment without bacteria, and it was obtained by preincubation of the monocytes with 5 to 10 bacteria per monocyte. No quantitative difference was observed between Staphylococcus epidermidis and Streptococcus sanguis as to the enhancement of the monocyte thromboplastin generation. An enhancement of the procoagulant activity generation was also observed after addition of bacteria to human or rabbit whole blood. Probably, this generation was also due to synthesis of thromboplastin by monocytes. It is conceivable that fibrin deposition on infected vegetations during bacterial endocarditis is mediated by thromboplastin synthesis by monocytes.

Animals↗
PubMed1979

Lactose metabolism in Streptococcus lactis: phosphorylation of galactose and glucose moieties in vivo.

Starved cells of Streptococcus lactis ML3 grown previously on lactose, galactose, or maltose were devoid of adenosine 5'-triphosphate contained only three glycolytic intermediates: 3-phosphoglycerate, 2-phosphoglycerate, and phosphoenolpyruvate (PEP). The three metabolites (total concentration, ca 40 mM) served as the intracellular PEP potential for sugar transport via PEP-dependent phosphotransferase systems. When accumulation of [14C]lactose by iodoacetate-inhibited starved cells was abolished within 1 s of commencement of transport, a phosphorylated disaccharide was identified by autoradiography. The compound was isolated by ion-exchange (borate) chromatography, and enzymatic analysis showed that the derivative was 6-phosphoryl-O-beta-D-galactopyranosyl (1 leads to 4')-alpha-D-glucopyranose (lactose 6-phosphate). After maximum lactose uptake (ca. 15 mM in 15 s) the cells were collected by membrane filtration and extracted with trichloroacetic acid. Neither free nor phosphorylated lactose was detected in cell extracts, but enzymatic analysis revealed high levels of galactose 6-phosphate and glucose 6-phosphate. The starved organisms rapidly accumulated glucose, 2-deoxy-D-glucose, methyl-beta-D-thiogalactopyranoside, and o-nitrophenyl-beta-D-galactopyranoside in phosphorylated form to intracellular concentrations of 32, 32, 42, and 38.5 mM, respectively. In contrast, maximum accumulation of lactose (ca. 15 mM) was only 40 to 50% that of the monosaccharides. From the stoichiometry of PEP-dependent lactose transport and the results of enzymatic analysis, it was concluded that (i) ca. 60% of the PEP potential was utilized via the lactose phosphotransferase system for phosphorylation of the galactosyl moiety of the disaccharide, and (ii) the residual potential (ca. 40%) was consumed during phosphorylation of the glucose moiety.

Biological Transport, Active↗