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Biomedical subjects

H J Harwick

Publications and source records attributed to H J Harwick.

At least 19 recordsLinked to original sources
PubMed1979

Effect of renal physicochemical milieu on stimulation of human lymphocytes by phytohemagglutinin.

The effect of changes in certain physicochemical parameters, analogous to those occurring in the kidney, on stimulation of normal human lymphocytes by phytohemagglutinin was studied. Increase in osmolality by sucrose or urea, and increases in concentration of sodium, potassium and calcium all significantly inhibited stimulation while magnesium did not. Lowering pH to 6.8 and 6.5 inhibited stimulation. Raising the pH to 8.0 had no effect bu at pH 8.4 stimulation was decreased. The effect was largely but not entirely due to decrease in viability.

Calcium↗
PubMed1977

Chemotactic activity of L-forms and mycoplasma.

L-forms of Streptococcus faecalis, Escherichia coli and Proteus mirabilis showed significantly less chemotactic activity for normal human leucocytes than did parent bacterial forms which were strongly chemotactic. Mycoplasma pneumoniae and Mycoplasma hominis did not demonstrate chemotactic activity.

Chemotaxis↗
PubMed1976

Arthritis in mice due to infection with Mycoplasma pulmonis. II. Serological and histological features.

Histological and serological data were obtained from a group of 160 mice given intravenous inoculations of 3.5 X 10(7) colony-forming units of Mycoplasma pulmonis and studied for 46 weeks. The basic pathology was that of an initial acute inflammatory response within the joint and periarticular tissues, slowly changing to a chronic inflammatory response seen predominantly in subsynovial areas with marked synovial proliferation. Occasional lymphoid follicles and plasma cells were seen in the subsynovial spaces. Titers of antibody to M. pulmonis were determined by both metabolic inhibition and indirect hemagglutination techniques. By the metabolic inhibition method, titers were highest between two and 22 weeks, and by indirect hemagglutination between four and 42 weeks. Antibodies to synovial antigens were present between nine and 26 weeks as determined by indirect hemagglunination. Serologic cross-reactions were found between M. pulmonis and normal mouse synovium in sera from infected mice and, by indirect hemagglutination, metabolic inhibition, and immunodiffusion techniques, in sera of rabbits or mice immunized with either M. pulmonis or mouse synovium.

Animals↗
PubMed1976

Klebsiella L-forms: effect of growth as L-form on virulence of reverted Klebsiella pneumoniae.

A strain of Klebsiella pneumoniae virulent for mice was serially passaged in vitro as a penicillin-induced L-form. Periodically, the L-form was reverted to the bacterial form by removal of penicillin, and the revertant was tested for virulence. Virulence was gradually reduced, and after 109 passages the revertant was totally avirulent. Virulence was not restored by 40 passages of the revertant through mouse peritoneum. The revertant grew less vigorously and did not infect mice when inoculated subcutaneously; in contrast, the parental form was found in all tissues examined. After phagocytosis in vitro or in vivo, the revertant survived but did not increase in numbers, whereas the parental form did increase in numbers. The revertant had a much smaller capsule than did the parental form. Immunization with the live revertant resulted in type-specific protection against infection with the parental form.

Animals↗
PubMed1976

Pyelonephritis. XIX. Immunization against enterococcal pyelonephritis.

A study has been done of immunization against Streptococcus faecalis pyelonephritis in the rat. Intravenous, subcutaneous, and bladder immunizations were tested with intravenous and retrograde challenge. Logarithmic and stationary growth phase organisms were used separately for both immunization and challenge. The only instance of significant, but incomplete, protection was in animals immunized subcutaneously or intravenously and challenged intravenously with log phase organisms. No correlation was found between circulating antibody response and infection. Serum bactericidal activity was not increased by immunization or infection.

Animals↗
PubMed1975

Urinary-tract infection: localisation and virulence of Escherichia coli.

Virulence of 15 strains of Escherichia coli from the human upper urinary tract was compared with that of 16 strains from the lower urinary tract, using an ascending infection in the mouse. No significant difference was found. There was no significant difference in frequency of K antigen and ability to ferment dulcitol between 32 lower strains and 31 upper strains. However, 22 strains containing K antigen, regardless of anatomical site of localisation, were more significantly likely to cause infection than 9 strains with no antigen. Similarly, 23 dulcitolfermenting strains, regardless of site of localisation, were significantly more likely to cause infection than 8 non-fermenting strains.

Animals↗
PubMed1973

In vitro activity of ampicillin or vancomycin combined with gentamicin or streptomycin against enterococci.

Minimum inhibitory and bactericidal concentrations of four antibiotics and their combinations were determined for 38 strains of enterococci by a microtitration tube dilution technique. The drugs were ampicillin, vancomycin, gentamicin, and streptomycin; the combinations were ampicillin-gentamicin, ampicillin-streptomycin, vancomycin-gentamicin, and vancomycin-streptomycin. At achievable serum concentrations, ampicillin alone killed 60% of strains, whereas combination with streptomycin increased this to 90% and with gentamicin to 100%. Vancomycin alone showed striking inhibitory activity, but very poor bactericidal activity at achievable concentrations. Combination with one of the aminoglycosides increased the bactericidal activity substantially. When combined with ampicillin, gentamicin was both more active and showed synergistic bactericidal activity significantly more often (P < 0.01) than streptomycin.

Ampicillin↗
PubMed1972

Phagocytosis of microbial L-forms.

Little data are available regarding L-form phagocyte interactions. Due to difficulty with more conventional methods, a serum-free technique of surface phagocytosis employing cellulose ester micropore filters, fluorochrome staining, and reflecting fluorescence microscopy was developed. Intracellular localization of L-frms was confirmed by electron microscopy. In timed experiments, phagocytosis of a group D Streptococcus (ATCC 23241) and its L-form (T53I) were maximal at 30 min, although the bacteria were consistently better phagocyted. Phagocytosis of an Escherichia coli (strain Yale) and its L-form was also demonstrated with the same technique. The lesser phagocytosis of L-forms may be related to their lower chemotactic activity.

Enterococcus faecalis↗
PubMed1971

Differential action of a streptococcal bacteriocin on mycoplasmas and microbial L-forms.

Bacteriocin activity of Streptococcus faecalis var. zymogenes was tested against a variety of bacteria, L-forms, and mycoplasmas. Both a partially purified liquid preparation and a colony overlay technique were used. Other S. faecalis strains were the only bacteria whose growth was inhibited. The liquid preparation inhibited growth of all but three of the tested L-forms (whether derived from gram-positive or gram-negative bacteria), and two of these exceptional organisms were inhibited when the colony overlay technique was employed. On the other hand, the L-form of Streptobacillus moniliformis and all 33 tested mycoplasmas grew readily in the presence of the bacteriocin when either method was employed. It is suggested that the presence of cholesterol in the Streptobacillus and mycoplasmal membranes, unique in this regard among procaryotic cells, may be responsible for the differential pattern of growth inhibition.

Bacteriocins↗