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K Holmgren

Publications and source records attributed to K Holmgren.

41 records · Page 3Linked to original sources
PubMed1982

Inhibitory activity of human urine on calcium oxalate crystal growth: effects of sodium urate and uric acid.

1. Freshly voided urine from healthy subjects was pooled and ultrafiltered (10,000 daltons). The ultrafiltrable and the macromolecular portions were preincubated with calcium oxalate, uric acid and sodium urate crystals and the effects on the inhibitory activity of calcium oxalate crystal growth assessed by monitoring the disappearance of [14C]oxalate from the solution. 2. The inhibitory activity of the ultrafiltrate was higher than that of the urinary macromolecular fraction. Both uninhibited and inhibited crystal growth processes followed second-order kinetics. 3. Calcium oxalate crystals adsorbed almost all the urinary macromolecular inhibitors whereas sodium urate or uric acid crystals adsorbed only 10-20%. 4. In the presence of a metastable solution of calcium oxalate, the incubation of the urinary macromolecular fraction with sodium urate crystals caused a pronounced reduction in the inhibitory activity. A similar effect was seen with uric acid crystals, but to a lesser degree. 5. We conclude that the effect of sodium urate or uric acid crystals alone on naturally occurring urinary macromolecular inhibitors of calcium oxalate crystal growth is weak, but that in the presence of metastable calcium oxalate this is greatly enhanced. A substantial adsorption of the inhibitors on to the crystals is suggested, possibly secondary to epitaxial growth of calcium oxalate on the surface of the urate crystals.

Calcium Oxalate↗
PubMed1981

Ecology and nature of immunoglobulin A1 protease-producing streptococci in the human oral cavity and pharynx.

The identity and proportional distribution of immunoglobulin A1 (IgA1) protease-producing streptococci in the oral and pharyngeal microflora were studied. A collection of 459 streptococcal strains, including reference strains of Streptococcus species, and fresh isolates from human dental plaque and buccal and pharyngeal mucosa were identified by biochemical means and were examined for IgA1 protease production. IgA1 protease production was demonstrated in some, but not all, strains of Streptococcus sanguis and Streptococcus mitior and in a group of strains of uncertain taxonomic affiliation. The property was not associated with particular biotypes within the two species. Strains of S. sanguis and S. mitior isolated from Macaca fascicularis also cleaved human IgA1. A significantly different proportion of streptococcal populations in different ecosystems produced IgA1 protease. The enzyme was released by 62.7% of streptococcal isolates from buccal mucosa in contrast to only 7.8% from pharyngeal mucosa. In samples from initial and mature dental plaque 38 to 40% of streptococcal isolates produced IgA1 protease. This difference was largely a result of the frequency by which IgA1 protease activity was present in S. mitior, the predominant streptococcal species in all samples. Among otherwise identical isolates of S. mitior, 67.8% from buccal mucosa in contrast to only 5.9% from pharyngeal mucosa produced IgA1 protease. The results indicate that IgA1 protease may confer an ecological advantage to streptococci colonizing surfaces exposed to a secretory IgA-mediated selection pressure.

Dental Plaque↗
PubMedDate not supplied

Gamma-radiation induced ADP-ribosyl transferase activity and mammalian longevity.

The levels of ADP-ribosyl transferase (ADPRT) activity following a standardized dose of 100 Gy gamma-radiation have been determined in leukocytes from 12 different mammalian species. Here, we report that the 100 Gy-induced levels of ADPRT correlated in a highly significant manner to the line spans of the mammals.

Adenosine Diphosphate Ribose↗