Electrical conductivity of a docusate sodium coacervate system

The conductivity of three xanthines (caffeine, theobromine, and theophylline) and three sugars (glucose, sucrose, and glucose-6-phosphate) was measured as part of a docusate coacervate system. The conductivity of the coacervate phase was always lower than the equilibrium phase. Conductivity of xanthines showed that caffeine had the highest conductivity, followed by theobromine and theophylline. At high concentrations, these values fell and the highest conductivity was seen in samples containing theobromine, caffeine, and theophylline. For sugars at high concentrations, the lowest values of conductivity were seen in sucrose samples. Saturated theophylline samples exhibited an increased volume in the coacervate phase volume. These findings are discussed with reference to various clinical parallels and thus supply evidence that coacervates can provide a useful model for human cytoplasm.

Expression and regulation of the plasmid-encoded hemolysin determinant of Escherichia coli

As a first approach towards studying the regulation of hemolysin synthesis in Escherichia coli, we have fused lacZ into the four hly genes (hlyC, hlyA, hlyBa and hlyBb) using the Mud-1 (Mu::lacZ, Y, Apr) phage. The sites of insertion of Mud-1 within the various hly genes of the Hly plasmid pHly152 were determined by the hemolytic phenotype of the Hly- mutants (Hly-ex/Hly-in or Hly-ex/Hly+in) and by complementation of these Hly- mutants with recombinant plasmids carrying cloned hly genes. It was found that hlyC, hlyA and hlyBa are transcribed from a relatively weak promoter (hlypL) located in front of hlyC. The activity of beta-galactosidase is considerably lower when Mud-1 is integrated in hlyBa than when it is inserted in hlyC, suggesting a considerable decline in hly gene expression from hlyC to hlyBa. The DNA sequence upstream of the coding region of hlyC was found to promote galK gene expression when a fragment covering this region was inserted into the promoter-probe vector pKO-11. A putative promoter sequence, which could correspond to hlypL, was identified in this sequence. The hlyBb gene appears to be transcribed from a different promoter and the direction of transcription seems to be opposite to that of the hlyC, A, Ba operon. The strength of this promoter (hlypR), based on the level of beta-galactosidase activity of Mud-1 insertion mutants in hlyBb, is considerably higher than that of hlypL.(ABSTRACT TRUNCATED AT 250 WORDS)

Microbial characteristics of the human dental caries associated with prolonged bottle-feeding

Plaque samples from caries lesions, white spot margins of these lesions, and caries-free smooth enamel surfaces, obtained from seven subjects with nursing bottle caries, all contained unusually high proportions of Streptococcus mutans. The proportion of lactobacilli present in plaque from caries lesions was statistically greater (p less than 0.01) than the proportion present in plaque obtained from white spot margins of these lesions or caries-free smooth enamel surfaces.

Stereophotographic measurement of change in facial soft tissue morphology following surgery

Changes in soft tissue morphology induced by surgery are generally analysed using midline profiles only, derived from photographs and cephalometric radiographs. Full face photographs supplement these records. Soft tissues and their changes can be measured in three dimensions using stereophotography. This report described how the three dimensional changes produced by facial surgery were measured for a patient undergoing surgery to the mandible.

Stimulation and inhibition by magnesium ions of intrinsic protein phosphorylating systems in synaptosomal membrane fragments from rat brain

Synaptosomal membrane fragments from rat brain were incubated with [gamma-32P]ATP in the presence of cyclic AMP or Ca2+ plus calmodulin and a range of Mg2+ concentrations. Incorporation of 32P into membrane polypeptides was examined by electrophoresis and radioautography. Cyclic AMP-stimulated reactions were stimulated by low concentrations and inhibited to varying degrees by high concentrations of Mg2+ in the range 1-50 mM. In general the Ca2+ plus calmodulin-stimulated reactions were maximally active in the range 30-50 mM Mg2+, but the Ca2+ plus calmodulin dependent phosphorylation of Protein I was progressively inhibited by concentrations of Mg2+ above 5 mM. These results emphasize the importance of establishing optimum Mg2+ concentrations in the study of specific membrane protein phosphorylating systems.

Cloned hemolysin genes from Escherichia coli that cause urinary tract infection determine different levels of toxicity in mice

After intraperitoneal injection of mice with Escherichia coli strains isolated from patients with urinary tract infections, the mortality due to hemolytic (Hly+) and nonhemolytic (Hly-) isolates was 77 and 40%, respectively. Deletion of the chromosomal hemolysin (hly) determinant in an E. coli O6:K15:H31 urinary tract infection strain led to a significant reduction in toxicity for mice, and its reintroduction on a recombinant plasmid partially restored the original toxicity. Although introduction of the cloned plasmid pHly152-encoded hly determinant into the Hly- E. coli O6 mutant strain increased toxicity by only a marginal degree, transformation with the cloned chromosomal hly determinants from two E. coli strains of serotypes O18ac:K5:H- and O75:K95:H? resulted in markedly greater toxicity, even exceeding that of the original Hly+ E. coli O6 wild-type strain.

Hemolytic Escherichia coli strains in the human fecal flora as potential urinary pathogens

Hemolysin production is presumed to be a virulence factor in extraintestinal, e.g. urinary tract, infections caused by Escherichia coli. In order to investigate its incidence among the fecal flora, particularly in combination with other presumptive virulence factors, 369 and 373 fecal isolates from Würzburg, FRG and Lima, Peru respectively were examined. 12% of the former and 4% of the latter were hemolytic (Hly+) compared to 33% of 249 E. coli strains isolated from urinary tract infections in Würzburg. In comparison to those which were non hemolytic (Hly-), Hly+ fecal E. coli isolates were associated to a far greater extent with other factors implicated in urinary tract virulence. 41% of these Hly+ strains (cf. 8% Hly-) possessed mannose resistant hemagglutination (MRHA types V, VI, VII). In addition they belonged to the "common O serogroups" O1, O2, O4, O6, O7, O8, O18, O25, O75 in 61% of cases (cf. 25% Hly-) and they possessed K5 antigen in 13% of instances (cf. 2.5% Hly-). The occurrence of these three virulence factors among Hly+ fecal E. coli strains is very similar to that observed among E. coli urinary isolates. One may conclude that these Hly+ fecal strains constitute a "pool" of potential urinary tract pathogens.

Synthesis of basement membrane proteins by rat mammary epithelial cells

A mammary epithelial cell line, Rama 25, growing on plastic, deposits fibronectin, type IV collagen, and laminin in punctate structures located beneath the basal surface of the cells. When grown on the surface of collagen gels, Rama 25 cells deposit these basement membrane proteins in a continuous layer between the basal surface of the cells and the surface of the collagen matrix. Rama 25 cells also penetrate the collagen matrix forming rudimentary duct-like structures. These structures are surrounded by a discontinuous layer of basement membrane proteins. The ducts of fetal and neonatal rat mammary glands contain few mature myoepithelial cells and our results suggest that some mammary epithelial cells, in contact with a collagenous stroma, are capable of synthesizing a basal lamina-like structure.

Hemolysin production as a virulence marker in symptomatic and asymptomatic urinary tract infections caused by Escherichia coli

Potential virulence, as defined by combined levels of adhesion to urinary epithelial cells, serum resistance, and mouse toxicity, was assessed for Escherichia coli strains causing symptomatic and asymptomatic urinary tract infections in relation to the carriage of hemolysin and other suspected virulence determinants. Hemolysin production (Hly), associated with certain O (O4, O6, O18, and O75), K (5), and hemagglutination (VI and VII) antigenic types but not colicin V production (Cva), was evident in 83 and 60% of isolates in groups possessing high potential virulence and in only 11 and 6% of those with low virulence. Strains of particular O-types were not more virulent per se, but among the serotypes, specific combinations of virulence factors appeared decisive, e.g., O18 HAVI B/D/G Hly(+) K5(+/-) and O18 HAIII/IVB/V Hly(-) Cva(+/-) K1(+/-) strains were, respectively, of high and low potential virulence. Isolates with high potential virulence were found to a similar extent in symptomatic and asymptomatic infections.

Relationship between plasmid and chromosomal hemolysin determinants of Escherichia coli

Plasmid hemolysin (hly) determinants have been shown previously to comprise three cistrons (hlyA, hlyB, hlyC), coding for the synthesis and transport of hemolysin. Using recombinant plasmids as specific probes for these cistrons, we were able to analyze the chromosomal hly determinants of nine Escherichia coli strains which belonged to serotypes O4, O6, O18, and O75 and were isolated from urinary tract infections and fecal flora. The chromosomal hly genes shared extensive sequence homology with the cloned plasmid hly determinant. Nevertheless, small differences were observed, and these were found to lie mainly within cistron A (hlyA), which has been shown to determine the hemolysin protein itself. These fine variations were not specific for the O-serotype.

Cloning of the chromosomal determinants encoding hemolysin production and mannose-resistant hemagglutination in Escherichia coli

We have cloned the chromosomal hemolysin determinants from Escherichia coli strains belonging to the four O-serotypes O4, O6, O18, and O75. The hemolysin-producing clones were isolated from gene banks of these strains which were constructed by inserting partial Sau3A fragments of chromosomal DNA into the cosmid pJC74. The hemolytic cosmid clones were relatively stable. The inserts were further subcloned either as SalI fragments in pACYC184 or as BamHI-SalI fragments in a recombinant plasmid (pANN202) containing cistron C (hlyC) of the plasmid-encoded hemolysin determinant. Detailed restriction maps of each of these determinants were constructed, and it was found that, despite sharing overall homology, the determinants exhibited minor specific differences in their structure. These appeared to be restricted to cistron A (hlyA), which is the structural gene for hemolysin. In the gene banks of two of these hemolytic strains, we could also identify clones which carried the genetic determinants for the mannose-resistant hemagglutination antigens Vb and VIc. Both of these fimbrial antigens were expressed in the E. coli K-12 clones to an extent similar to that observed in the wild-type strains. These recombinant cosmids were rather unstable, and, in the absence of selection, segregated at a high frequency.

Serum resistance among Escherichia coli strains causing urinary tract infection in relation to O type and the carriage of hemolysin, colicin, and antibiotic resistance determinants

The sensitivity to normal human serum of 91 smooth strains of Escherichia coli isolated from urinary tract infections was determined. Production of hemolysin, which was common and associated primarily with the types O4, O6, O18, and O75, was significantly correlated with high levels of serum resistance, both within the total population and within individual O types. In contrast, serum resistance was not significantly associated with antibiotic resistance (whether transmissible or not), with colicinogeny in general, or with colicin V production in particular. This indicates that the carriage of R and ColV plasmids, shown previously to be capable of conferring increased levels of serum resistance on individual strains of E. coli isolated from other sources, does not play an important part in determining the serum sensitivity of the E. coli population involved in urinary tract infection.

The role of macrophages in primary and secondary infection of mice with Salmonella typhimurium

Elimination of macrophages with high-molecular dextran sulphate (DS) markedly impairs resistance of mice to primary infection with smooth, virulent strains of Salmonella typhimurium, whereas stimulation of this system by killed Bordetella pertussis organisms increases resistance. In infection with rough, avirulent strains of S. typhimurium the elimination of macrophages was not followed by an essential loss of resistance, and it appears that other non-specific defence mechanisms, for example the complement system, may have compensated for the lack of macrophages. Macrophages, therefore, play an important role in defence during primary infection with virulent strains. In immunity to challenge infection with S. typhimurium, macrophages play an even more significant role. Treatment with DS completely removes immunity, and both humoral and cell-mediated immune mechanisms seem to require the participation of macrophages.

Genetics and pathogenic role of Escherichia coli haemolysin

While clear evidence exists for the direct involvement of cytolysins in the pathogenesis of Gram-positive bacteria, the significance of Gram-negative haemolysins remains unclear. This paper presents briefly data indicating a role for haemolysin production in infections caused by Escherichia coli and also experiments which have allowed an analysis of the molecular basis of the haemolysis among pathogenic and non-pathogenic strains of this species.

Spread of R-plasmids among Escherichia coli causing urinary tract infections

The incidence of multiple-antibiotic resistance among Escherichia coli isolated from urinary tract infections at Charing Cross Hospital, London, increased over the last 10 years, and its distribution was related to O-type. Among strains of the eight O-types most frequently causing such infections at this hospital, O4, O9, and O18 had a high incidence of multiple resistance (35, 22, and 19%, respectively); O2 and O6 had a intermediate incidence (14 and 11%, respectively); and O7, O1, and O75 had a low incidence (8, 6, and less than 3%, respectively). This nonrandom distribution appears to be a consequence of unequal plasmid recipient ability. After overnight mating with antibiotic-resistant donors, R-plasmid infection frequencies among antibiotic-sensitive urinary tract isolates differed by up to 10(5)-fold, and such differences were correlated with the variation in the incidence of antibiotic resistance among the O-types. The inherent differences in the ability to achieve significant R-plasmid spread, which appear to be determined by the host, not the plasmid, may be compounded in some cases by the inhibition of potential mating partners by colicin production.

Clinical and hemodynamic evaluation of the 19 mm Björk-Shiley aortic valve prosthesis

Between November, 1973, and March, 1980, 43 patients underwent isolated aortic valve replacement with 19 mm Björk-Shiley prostheses at the Johns Hopkins Hospital. There were 4 male and 39 female patients ranging from 12 to 75 years old (mean, 54.5 years). Average weight was 62 +/- 2 kg and average body surface area, 1.64 +/- 0.3 m2. Five patients died within thirty days of operation; however, since 1975, hospital mortality has been 5.9%. The 38 survivors have been followed up for as long as 85 months (mean, 40 months). There were 4 late deaths, and actuarial survival in patients discharged from the hospital was 81% at five years. All long-term survivors were in New York Heart Association Functional Class I (29 patients) or Class II (5 patients). Preoperative and postoperative echocardiograms in 17 patients demonstrated significant decreases in mean left ventricular wall thickness (12.9 +/- 1.8 mm vs 10.3 +/- 1.4 mm; p less than 0.001) and in left ventricular mass (262 +/- 95 gm vs 188 +/- 50 gm; p less than 0.02). Postoperative cardiac catheterization data were obtained from an additional 24 patients undergoing aortic valve replacement with the 19 mm Björk-Shiley prosthesis at the National Heart Institute. Average peak systolic gradient at rest was 16 mm Hg (range, 0 to 45 mm Hg) and was found to be directly related to body surface area (r = 0.60, p less than 0.002). Average effective valve orifice area was 1.06 cm2 (range, 0.63 to 2.02 cm2). For patients with small aortic roots, aortic valve replacement with the 19 mm Björk-Shiley valve is a satisfactory and, perhaps, preferable alternative to aortic annuloplasty to accommodate larger sized prostheses.

Escherichia coli heat-labile enterotoxin: DNA-directed in vitro synthesis and structure

Escherichia coli heat-labile enterotoxin was synthesized in a cell-free system directed by DNA of the plasmid P307. Synthesis of the toxin, assayed by the elongation induced in Chinese hamster ovary cells, was strongly stimulated by cyclic AMP and occurred at physiological levels of Mg2+ only when the polyamine spermidine was present. Activity was abolished by heat and antisera prepared against the enterotoxins of both E. coli P263 and Vibrio cholera. Tritium-labeled enterotoxin was purified by immunoprecipitation and examined by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. When gel slices were assayed for the ability to stimulate adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] activity in erythrocyte ghosts, two peaks were found, one at Mr 26,000 and frequently, but not always, another at Mr 23,000. Detection of radiolabeled protein by fluorography and scintillation counting of gel slices revealed three prominent polypeptides, two corresponding to the peaks having adenylate cyclase-stimulating activity and a further one of Mr 11,500, identical to that of the cholera subunit B. The data suggest that the E. coli heat-labile enterotoxin synthesized in the cell-free system has a subunit structure.

Plasmid carriage and the serum sensitivity of enterobacteria

The carriage of a range of plasmids by rough, serum-sensitive laboratory strains of Escherichia coli made no difference to their reactivity in human serum as determined by two methods. Plasmid-carrying enterobacteria isolated from polluted river water gave a variety of responses to serum. Smooth E. coli river isolate C8 was killed by serum but only after a delay of 1 h, and curing of antibiotic resistance and colicin determinants from this strain led to a small but significant increase in serum sensitivity. Plasmids from eight strains were transferred by conjugation to a cured derivative of C8 (C8(-)Nal(R)), and in six cases a significant increase in the serum resistance of the progeny was observed. Plasmid-mediated enhancement of resistance was particularly marked with plasmids R1 and NR1, and a round of replication mutant of NR1 conferred greater resistance than did the normal R factor. However, R1 and NR1 were unable to modify the serum response of a cured strain (P21(-)Nal(R)) derived from promptly serum-sensitive isolate P21. These findings suggest that lipopolysaccharide O-side chains, the cell surface components responsible for the delay in serum killing, are essential for the expression of plasmid factors that modify sensitivity to serum. Examination of K(A)(-) variants of two isolates indicated that the K(A) antigen has only a marginal effect on the serum response.

Two major groups of colicin factors: their molecular weights

Colicin factors are thought to fall into two taxonomic groups which differ in, amongst other properties, the molecular weight of the plasmid DNA and the host range of the colicin protein. This hypothesis is supported by the plasmids found in 26 colicinogenic strains. Two small Col factors may have arisen from larger factors, judging from similarities between their colicins.

A comparative evaluation of a case of cystosarcoma phylloides: ultrasound, xeroradiography and thermography

The results of xeroradiography, thermography, and ultrasonic gray scale echography in a case of cystosarcoma phylloides are presented. Echography better described the lesion than the other techniques. Gray scale echography displays the infrastructure of the breast tissues and differentiates between types of soft tissue.