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Biomedical subjects

H H Messer

Publications and source records attributed to H H Messer.

At least 91 records · Page 5Linked to original sources
PubMed1985

A comparison of the antibacterial and cytotoxic effects of parachlorophenol.

The antibacterial and cytotoxic effects of parachlorophenol (as 35% camphorated PCP and 2% aqueous PCP) were compared directly, using the agar overlay technique. Human pulp fibroblasts and L929 cells were grown to confluence in 60-mm petri dishes. Bacterial suspensions (S. aureus, E. coli) in agar were poured as a thin layer in 60-mm petri dishes. All were overlaid with agar. Cells were exposed to medicament via filter paper discs placed on the agar surface. After 24 hours, the zone of cell lysis (fibroblasts) or inhibition of bacterial growth was measured as diameter in mm. A dose-response relationship was observed for both fibroblasts and bacteria. The zone of inhibition for fibroblasts was larger than that for bacteria, indicating that the cytotoxicity of parachlorophenol exceeds its antibacterial activity.

Animals↗
PubMed1983

An in vitro study of the comparative effectiveness of obturating curved root canals with gutta-percha cones, silver cones, and stainless steel files.

The quality of apical seal obtained with gutta-percha cones, silver cones, and stainless steel files was assessed in 120 freshly extracted teeth with moderately or severely curved root canals. Teeth were coated with wax, except in the apical foramen area, and immersed in 2 percent methylene blue solution for 48 hours. Apical leakage was quantitated by a linear measurement of the distance that the dye penetrated along the root canal and by a volumetric measurement of the quantity of dye within the root. There was a highly significant (p less than 0.001) correlation between the two measurements. Root canals filled with silver cones showed significantly less apical leakage than those filled with gutta-percha or stainless steel files, regardless of degree of curvature. For both silver cones and stainless steel files, leakage was less in severely curved roots than in moderately curved roots.

Dental Bonding↗
PubMed1982

Removal of trace metals from culture media and sera for in vitro deficiency studies.

Culture media and sera contain substantial quantities of trace metals such as zinc and copper, so that they cannot be used for cell culture studies of trace metal deficiencies unless the element in question is first removed. By coupling the chelator iminodiacetate to an insoluble agarose matrix, we have been able to extract zinc selectively from both media and sera, without exposing cells directly to the chelator. The procedure reduced the zinc concentration of media to unmeasurably low levels, and serum zinc concentration by approximately 90%. The development of zinc deficiency in vitro was demonstrated by a reduced lymphocyte blastogenic response, which could be prevented by the addition of zinc to the extracted culture medium. The extraction procedure is potentially applicable to a range of trace elements (e.g., Zn, Cu, Mn, Fe) and to virtually any cell type that can be cultured.

Adult↗
PubMed1982

Mandibular bone turnover during calcium deficiency in the rat.

Bone resorption and deposition during calcium deficiency were compared in the mandible, femur, and vertebrae. While resorption did not differ markedly among the three sites, mineral deposition was lowest in the mandible, leading to a greater net loss of mineral than from femur or vertebrae.

Animals↗
PubMed1982

Bone cell membranes.

While many, if not most, of the details remain to be worked out, bone cell function is increasingly being explained in terms of cell membrane phenomena. Ultrastructurally, bone cell membranes do not show remarkable features beyond those associated with the ruffled border and clear zone of the osteoclast or specializations associated with the formation of matrix vesicles. Major physiologic properties of bone cell membranes are related to calcium transport, electrical properties and hormonal responses. Major advances in these areas are occurring with the development of separation techniques for the isolation of subpopulations of bone cells that respond primarily to parathyroid hormone or calcitonin. The combined actions of calcium and cyclic AMP in large part mediate the hormonal and possible electrical responses of bone cells.

Animals↗
PubMed1981

A comparison of bone loss from different skeletal sites during acute calcium deficiency in mice.

Severe Ca deficiency was produced by the combined stresses of a Ca-deficient diet and lactation in female mice. Alveolar bone loss was assessed by changes in alveolar crest height and in quantity of supporting trabecular bone. Changes in the femur were measured by changes in mineral content and in the cross-sectional area of the midshaft region, and in vertebrae by changes in mineral content. A similar decrease in bone was observed in all sites during progression of Ca deficiency with a similar increase during recovery. Maximum bone loss amounted to more than 50 per cent. Alveolar bone loss was characterized by a reduction in trabecular bone without loss of alveolar crest height.

Alveolar Process↗
PubMed1981

Turnover of bone zinc during normal and accelerated bone loss in rats.

The ability of the skeleton to serve as a reservoir of available zinc was investigated in weanling and 7-week-old rats. Bone turnover was measured by the loss of previously incorporated 3H-tetracycline (TC), in conditions of normal turnover accompanying growth or accelerated loss produced by calcium deficiency. The 4-week studies involved four experimental groups per age group (all combinations of high and low calcium, high and low zinc). By measuring loss of 3H-TC and whole bone (humerus) contents of Zn and Ca, it was possible to calculate the deposition and resorption of Zn and Ca during the experimental period. Several conclusions emerged from the study: 1) availability of Zn from the skeleton was dependent on the rate of bone resorption, but not on Zn status; 2) redeposition of Zn in the skeleton following resorption was extensive, and independent of the rate of bone mineral deposition; and 3) in Ca deficiency there was an increased deposition of Zn, suggesting a partial substitution of Zn for Ca in bone mineral. The results support the concept that the skeleton does not serve as a reservoir for Zn. Very little Zn is made available by bone resorption, and even then Zn is lost only in a passive manner that is dependent on, but does not influence, bone turnover. The availability of Zn from the skeleton is not mediated by Zn status.

Aging↗
PubMed1977

Hormonal responses of bone in a continuous flow cultural system.

Calvaria from five-day-old mice incubated in a continuous flow system (10 calvaria per culture chamber with 1 ml volume; flow rate 1ml/hr.). In 24-hour cultures, calvaria showed less resorption than in stationary culture. Short-term responses to PTH and calcitonin were similar to those observed in vivo.

Animals↗