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Biomedical subjects

J P Babu

Publications and source records attributed to J P Babu.

At least 19 recordsLinked to original sources
PubMed1995

Inhibition of neutrophil and monocyte defensive functions by nicotine.

To learn more about the effects of smokeless tobacco on the defensive functions of neutrophils, we studied the influence of nicotine on these cells in vitro, looking at their bactericidal activity against oral pathogens, and at their ability to produce microbicidal reactive oxygen species (oxygen radicals). Exposure of human blood neutrophils to nicotine (0.01% to 0.1%) inhibited their ability to kill Actinomyces naeslundii, Actinobacillus actinomycetemcomitans, and Fusobacterium nucleatum. Although these concentrations of nicotine are high, such concentrations are relevant to phagocytes in the gingival sulcus, because smokeless tobacco contains 0.5% to 3.5% nicotine by dry weight. Nicotine had no such inhibitory effect when the killing assay was performed in an anaerobic environment, implying that nicotine preferentially affected oxygen-dependent killing mechanisms. To further investigate the effects of nicotine on production of oxygen radicals, neutrophils were primed with lipopolysaccharide and triggered with f-met-leu-phe or phorbol ester in the presence of nicotine. Nicotine inhibited production of superoxide anion (measured by reduction of cytochrome c) and hydrogen peroxide (measured by oxidation of phenol red). Nicotine inhibition of superoxide production was reversible by washing away the nicotine. By observing that nicotine inhibited the reduction of cytochrome c by reagent potassium superoxide, we determined that nicotine directly absorbed superoxide. In addition, by examining nicotine inhibition of the uptake of oxygen by neutrophils, we determined that nicotine also interfered with the production of oxygen radicals by these cells. Nicotine also inhibited production of superoxide and interleukin-1 beta by monocytes. Nicotine did not affect the viability of neutrophils and monocytes, as determined by their ability to exclude trypan blue dye. Inhibition of the aerobic antimicrobial functions of neutrophils and monocytes by nicotine may alter the microbial ecology of the oral cavity, and this might be one mechanism by which nicotine compromises the oral health of users of tobacco products.

Actinomyces↗
PubMed1995

Attachment of Fusobacterium nucleatum to fibronectin immobilized on gingival epithelial cells or glass coverslips.

To learn more about colonization of the oral epithelium by Fusobacterium nucleatum and the role of fibronectin in mediating adhesion of this microorganism, we studied attachment of this bacterium to cultured gingival epithelial cells that were coated with exogenous, purified plasma fibronectin. The three strains of F. nucleatum studied adhered in large numbers to epithelial cells that had been coated with fibronectin, compared with buffer-coated control cells. Bacterial adherence was also enhanced when epithelial cells were coated with whole human saliva. However, cells coated with saliva depleted of fibronectin did not facilitate adhesion of bacteria. Bacterial adhesion was restored when purified fibronectin was added back. We also tested adherence of bacteria to coverslips coated with fibronectin, saliva, and saliva depleted of fibronectin. The bacteria adhered to coverslips coated with fibronectin or whole human saliva, but did not adhere to coverslips coated with fibronectin-depleted saliva. Bacterial adhesion to coverslips was restored upon addition of purified fibronectin to the fibronectin-depleted saliva. Bacterial attachment to fibronectin-coated coverslips was found to be temperature-dependent, with maximal adhesion observed at 37 degrees C. Pre-treatment of F. nucleatum with soluble fibronectin inhibited attachment of the bacteria by 92%, whereas pre-treatment with bovine serum albumin had no effect. Pre-treatment of bacteria with laminin or type IV collagen caused moderate inhibition of attachment by 60% and 50%, respectively. Treatment of fibronectin-coated coverslips with Fab fragments of anti-fibronectin IgG blocked the attachment of F. nucleatum by 93%. Fab fragments of the other antisera tested had no inhibitory effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Adhesion↗
PubMed1994

Corrected formula for estimating peripheral blood flow by impedance plethysmography.

In this paper, the limitations of the conventional formula for the computation of peripheral blood flow from impedance plethysmograms are highlighted, and a correction to the formula is suggested. A conductivity cell experiment is described to show the dependence of the value of the blood flow index (BFI), obtained from the conventional formula, on the mean resistivity of the cell. It is also shown that the value of the corrected BFI is independent of the mean resistivity. Anomalies observed in the amplitude of systolic waves in impedance plethysmograms of patients with oedema are explained.

Adult↗
PubMed1992

Glycerol-induced unraveling of the tight helical conformation of Escherichia coli type 1 fimbriae.

Glycerol was found to unravel the helical conformation of Escherichia coli type 1 fimbriae without appreciable depolymerization. The linearized fimbrial polymers have a diameter of 2 nm, react strongly with a monoclonal antibody directed at an inaccessible epitope on native fimbriae, and display greater mannose-binding activity and trypsin sensitivity than native fimbriae. Removal of glycerol by dialysis results in spontaneous reassembly of the linear polymers into structures morphologically, antigenically, and functionally indistinguishable from native fimbriae.

Escherichia coli↗
PubMed1991

Isolation and characterization of a 180-kiloDalton salivary glycoprotein which mediates the attachment of Actinomyces naeslundii to human buccal epithelial cells.

The adherence of Actinomyces naeslundii to human buccal mucosa is mediated by specific interactions between the bacterial cell surface fimbriae and complementary beta-linked galactoside receptors on the epithelial cell surface. The buccal mucosa and the bacteria that colonize its surface are constantly bathed in saliva. Several salivary components are thought to play an important role in modulating adhesive interactions between oral bacteria and the buccal epithelium. We have observed that pretreatment of isolated buccal epithelial cells (BEC) with human parotid saliva increased the attachment of three different strains of A. naeslundii. By employing affinity chromatography, ion-exchange and high-pressure liquid chromatographic techniques we have isolated a 180 kDa A. naeslundii-binding salivary glycoprotein (An-SPG). This salivary glycoprotein was capable of mediating separate but specific binding interactions with A. naeslundii and BEC. Pretreatment of BEC with increasing amounts of An-SGP resulted in a corresponding increase in the attachment of A. naeslundii. The adherence of A. naeslundii to An-SGP-coated BEC is sensitive to the same inhibitors previously shown to block adherence of A. naeslundii to uncoated BEC, namely lactose- and galactosyl-binding lectins. When a solubilized extract of freshly isolated and washed BEC was reacted on a Western blot with antibodies to An-SGP, a prominent 180 kDa immunoreactive band was detected. Furthermore, the immunoreactive component was demonstrated on the BEC surface when assayed by immunofluorescence using An-SGP-specific antibodies, suggesting that An-SGP or a protein structurally and immunologically identical to the isolated glycoprotein is present on BEC.

Actinomyces↗
PubMed1990

Impedance plethysmography: basic principles.

Impedance Plethysmography technique has been discussed with explanation of two compartment model and parallel conductor theory for the estimation of peripheral blood flow and stroke volume. Various methods for signal enhancement to facilitate computation of blood flow are briefly described. Source of error in the estimation of peripheral blood flow is identified and the correction has been suggested.

Humans↗
PubMed1990

Technical aspects of impedance plethysmography.

This paper describes the basic methods for measurement of body impedance, electrodes and their configuration, and the measuring instrument with its limitations. A microcomputer assisted impedance plethysmograph system, developed at BARC and different lead configurations for impedance plethysmographic investigation are also described. Typical impedance plethysmographic waveforms recorded from a normal subject and measurement of their amplitude and various time intervals are illustrated.

Extremities↗
PubMed1990

Diagnosis of peripheral arterial occlusive diseases using impedance plethysmography.

Impedance plethysmographic observations have been compared with arteriographic findings in 216 patients with peripheral arterial occlusive diseases. Impedance plethysmographic diagnosis in these patients was obtained by Parulkar's method without apriori knowledge of arteriographic diagnosis. But for minor discrepancy in the anatomical location of the block in few patients, impedance plethysmographic observations correlated very well with arteriographic findings. Impedance plethysmographic diagnosis was found to be correct in 312, wrong in 53, false negative in 8 limbs respectively, yielding a sensitivity of 97.5% and specificity of 98.1% of this technique.

Adolescent↗
PubMed1986

Isolation and characterization of a 60-kilodalton salivary glycoprotein with agglutinating activity against strains of Streptococcus mutans.

A bacterial agglutinin specific for strains of Streptococcus mutans was isolated from human saliva. Physiochemical analyses showed the agglutinin to be a glycoprotein with a molecular weight of 60,000. The agglutinin aggregated four of the eight strains of Streptococcus mutans tested but did not aggregate the strains of Streptococcus salivarius, Streptococcus sanguis, and Streptococcus mitis tested. Chemical modification of carbohydrate moieties of the agglutinin with sodium metaperiodate had no effect on aggregation, whereas modification of the polypeptide portion with trypsin abolished aggregating activity. A set of five murine hybridoma antibodies was employed to further analyze the agglutinin. Two carbohydrate-specific antibodies, directed against D-mannose and N-acetylgalactosamine moieties, respectively, failed to block agglutinin- or whole saliva-mediated aggregation of S. mutans cells. In contrast, two antibodies directed against pronase-sensitive antigenic sites blocked both agglutinin- and saliva-mediated aggregation of S. mutans cells. Western blot analysis with the agglutinin-specific hybridoma antibodies demonstrated the agglutinin in whole saliva and in artificial tooth pellicles formed on hydroxyapatite beads incubated with saliva. These results suggest that a 60-kilodalton glycoprotein of human saliva is a bacterial agglutinin with specificity for certain strains of S. mutans. They further suggest that aggregation is mediated by polypeptide rather than carbohydrate determinants of the glycoprotein.

Agglutination↗
PubMed1986

Inhibition of the interaction of Streptococcus sanguis with hexadecane droplets by 55- and 60-kilodalton hydrophobic proteins of human saliva.

The effect of salivary secretions on the hydrophobicity of Streptococcus sanguis was investigated. Pretreatment of the bacteria with paraffin-stimulated whole saliva resulted in a 79% inhibition of adhesion to hexadecane droplets. Column chromatography on Sepharose 4B and sodium dodecyl sulfate gel electrophoretic analysis indicated that the inhibitory activity of saliva resided in a fraction containing material of approximately 60,000 molecular weight. The active components, which we have termed the hydrophobic components (HC), bind to octyl-Sepharose beads. Pretreatment of S. sanguis with HC resulted in a dose-dependent inhibition of the streptococcus-hexadecane interaction that reached a maximum of 85%. Furthermore, HC effectively blocked the ability of S. sanguis to adhere to hydroxyapatite beads coated with either whole saliva or HC. Sodium dodecyl sulfate-polyacrylamide gel analysis indicated that HC eluted from octyl-Sepharose consisted primarily of two proteins (60 kDa and 55 kilodaltons) which could be resolved by high-pressure liquid chromatography. Both of these proteins were able to inhibit the binding of S. sanguis to hexadecane in a dose-dependent manner; however, the 60-kilodalton molecule was slightly more effective in this assay. Amino acid analysis of these proteins showed that both proteins contained a high percentage of nonpolar amino acids. These findings suggest that certain components of saliva influence the interaction of S. sanguis with hydrophobic surfaces.

Adhesiveness↗
PubMed1986

Interaction of a 60-kilodalton D-mannose-containing salivary glycoprotein with type 1 fimbriae of Escherichia coli.

A 60-kilodalton glycoprotein previously isolated and purified from human saliva (J. B. Babu, E. H. Beachey, D. L. Hasty, and W. A. Simpson, Infect. Immun. 51: 405-413, 1986) was found to interact with type 1 fimbriae and prevent adhesion of type 1 fimbriated Escherichia coli to animal cells in a D-mannose-sensitive manner. Purified salivary glycoprotein agglutinated type 1 fimbriated E. coli and, at subagglutinating concentrations, blocked the ability of type 1 fimbriated E. coli to attach to human buccal epithelial cells or agglutinate guinea pig erythrocytes. Both interactions were inhibited by alpha-methyl-D-mannoside but not by alpha-methyl-D-glucoside. Complexing of the glycoprotein to type 1 fimbriae was demonstrated by molecular sieve chromatography and modified Western blots. When mixed with type 1 fimbriae, the radiolabeled salivary glycoprotein coeluted with type 1 fimbriae from a column of Sepharose 4B. When blotted from a sodium dodecyl sulfate gel to nitrocellulose sheets, the glycoprotein interacted directly with type 1 fimbriae applied to the blots. Both of the latter interactions also were blocked by alpha-methyl-D-mannoside but not by alpha-methyl-D-glucoside. Chemical modification of the glycoprotein with sodium metaperiodate abolished its ability to interact with isolated type 1 fimbriae or type 1 fimbriated E. coli. These results suggest that the carbohydrate moiety of the 60-kilodalton glycoprotein serves as a receptor for type 1 fimbriae in the oral cavity, and we postulate that the interaction may cause agglutination and early removal of E. coli, thereby preventing colonization by these organisms of oropharyngeal mucosae and dental tissues.

Antibodies, Monoclonal↗
PubMed1986

Interaction of salivary fibronectin with oral streptococci.

Immunoreactive Fibronectin (Fn) has been demonstrated in stimulated human parotid saliva by western blot analysis and also found to be a component of the artificial tooth pellicles derived from hydroxyapatite (HA) beads coated with parotid saliva. Saliva depleted of gelatin-binding components showed a significantly lower degree of reactivity with anti-Fn antibodies than did the control saliva when tested by and enzyme-linked immunosorbent assay (ELISA). Depletion of gelatin-binding components from saliva was also found to affect the degree of saliva-mediated aggregation of four of the seven oral streptococci tested [Streptococcus mutans strains GS-5 and OMZ 176, S. sobrinus, and S. rattus]. Similarly, the adherence of the same four micro-organisms to the artificial tooth pellicles (derived form saliva which had previously been depleted of gelatin-binding component) was significantly inhibited (37-53%) when compared with the control saliva-coated HA beads. Pre-treatment of streptococci with 100 micrograms of soluble Fn also caused a 34-57% inhibition of adherence of the same oral streptococci to saliva-treated HA beads. Quantitation of Fn in human parotid saliva showed that the amounts of immunoreactive Fn varied form 2 to 6 micrograms/mL of parotid saliva. Furthermore, the Fn from parotid saliva was found to be adsorbed onto the bacterial surfaces, as demonstrated by immunofluorescence and ELISA. The presence of Fn in parotid saliva and its ability to bind to HA beads (artificial pellicles), in conjunction with the ability of soluble Fn to inhibit the adherence of streptococcal strains to the artificial tooth pellicles, suggest that the microbial ecology of the oral cavity may, in part, be influenced by the interactions mediated by salivary fibronectin.

Adhesiveness↗
PubMed1985

Protection against Escherichia coli-induced urinary tract infections with hybridoma antibodies directed against type 1 fimbriae or complementary D-mannose receptors.

Hybridoma antibodies directed against quaternary structural epitopes of the type 1 fimbrial adhesin of Escherichia coli or against D-mannose, the sugar determinant in the complementary host cell receptor, prevented the attachment of mannose-sensitive E. coli to various eucaryotic cells. Passive intraperitoneal administration of the fimbria-specific or D-mannose-specific antibodies protected mice against retrograde colonization with mannose-sensitive E. coli instilled into their urinary bladders. Monoclonal antibodies directed against fimbrial subunits rather than quaternary structural epitopes or against N-acetylgalactosamine rather than D-mannose residues lacked protective activity. These studies provide evidence that bacterial colonization can be blocked or interrupted by antibodies directed against either the adhesin or the complementary host cell receptor of pathogenic microorganisms.

Adhesiveness↗
PubMed1983

Interaction of human plasma fibronectin with cariogenic and non-cariogenic oral streptococci.

The interaction of purified human plasma fibronectin (Fn) with bacteria was studied with a variety of oral streptococci. Each of the strains of Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguis, and Streptococcus mitis tested was aggregated by Fn to various degrees, depending on the concentration of Fn added to the test mixtures. Binding assays performed with radiolabeled Fn and various strains of streptococci demonstrated various capabilities to bind Fn, and the amount of Fn bound by each strain was paralleled by its Fn-induced aggregation, with S. mutans 6715 giving the highest values in both assays. Because of the avid binding of Fn by certain strains of potentially cariogenic streptococci, we investigated the possibility that Fn may be present in human saliva and may be adsorbed from saliva onto artificial tooth pellicles. Immunoreactive Fn was detected in paraffin-stimulated whole saliva by enzyme-linked immunosorbent assays of saliva adsorbed onto gelatin-coated cuvettes and by immunoelectroblots (Western blots) of salivary components separated on sodium dodecyl sulfate-polyacrylamide slab gels. Furthermore, immunoreactive Fn was found to be present in artificial tooth pellicles formed by incubating hydroxyapatite beads with whole human saliva. These results demonstrate that certain strains of oral streptococci bind to and are aggregated by Fn. The presence of Fn in artificial tooth pellicles suggests that this macromolecule may play a role in the attachment of potentially cariogenic and other oral streptococci to dental tissues.

Fibronectins↗
PubMed1979

Evaluation of ten anaerobic blood culture media.

Selection of an anaerobic blood culture based upon clinical findings that have compared the isolation rates of bacteremic agents from different blood culture media. No agreement has been reached as to which of the commercially available blood culture media is optimal for detection of bacteremia. The purpose of this study was to determine the rates of recovery of anaerobic microorganisms from various anaerobic blood culture media. The blood culture media were inoculated with a small inoculum of microorganisms in the presence or absence of an erythrocyte-serum mixture. The results demonstrated that the type of medium and the erythrocyte-serum mixture influenced the ability of blood culture media to support the growth of microorganisms. The majority of the media failed to support the growth of 87% or more of the microorganisms within four days after inoculation. Pre-reduced brain-heart infusion broth supported the growth of a larger proportion of microorganisms than the other types of blood culture media.

Anaerobiosis↗
PubMed1979

Recovery of Haemophilus influenzae from twenty-three blood culture media.

Haemophilus influenzae is an important agent of bacteremia and has fastidious growth requirements. The purpose of this investigation was to determine the ability of commercial blood culture media to support the growth of this fastidious microorganism. Twenty-three types of blood culture media were inoculated with individual suspensions of eight strains of H. influenzae in the presence or absence of an erythrocyte-serum mixture. The rates of recovery of the H. influenzae strains from the various types of blood culture media were compared. The results demonstrated that the type of medium, the manufacturer, the erythrocyte-serum mixture, and the strain of H. influenzae influenced the recovery rates of H. influenzae. Optimal recovery of the strains of H. influenzae was obtained from brain heart infustion blood culture medium (GIBCO). Trypic soy broth (GIBCO) and supplemental peptone of Becton, Dickinson and Co. also were found to be superior to the remaining types of media tested for the recovery of H. influenzae.

Blood↗