Absence of age-related changes in venous responsiveness to nitroglycerin in vivo in humans

We have previously demonstrated a progressive loss in the ability of the beta-receptor agonist isoproterenol to relax veins with increasing age. In this study the influence of age on the responsiveness of medium-sized veins to local infusions of nitroglycerin was studied in two groups of 15 healthy male volunteers using the dorsal hand vein compliance technique. A dorsal hand vein was preconstricted with submaximally effective doses of phenylephrine and a dose-response curve with nitroglycerin was established. The nitroglycerin dose that caused a 50% venodilation ranged from 0.7 to 22.4 ng/min (geometric mean 3.6 ng/min) in the younger group (aged 19 to 29 years; mean +/- SD 23 +/- 3 years) and from 0.2 to 17.9 ng/min (geometric mean 3.6 ng/min) in the older subjects (aged 50 to 74 years; mean +/- SD 63 +/- 7 years) (P = 0.49 between geometric means). The mean (+/- SD) maximal venodilation, based on the pretreatment baseline, was 103% +/- 65% in the younger and 125% +/- 64% in the older subjects (P = 0.18). These results indicate that there is no age-related change in venous responsiveness to nitroglycerin.     

A pilot study of the association between cariogenic oral bacteria and preterm birth*

Objectives: We examined the associations between preterm birth and low birth weight and maternal caries history, maternal periodontal status, and salivary levels of mutans streptococci and Lactobacilli. Design: This study was a matched case–control study in women during their pregnancy or up to 8 weeks after delivery. Subjects and methods: Thirty‐four women delivering before 37 weeks gestation were recruited along with 73 term controls matched for age and race/ethnicity. Demographic and obstetric information was collected from questionnaires and medical records and oral examinations along with commercial salivary tests were completed within the study groups. Main outcome measures: The main outcome variables were the preterm birth and low birth weight status. The independent variables measured were the salivary levels of Lactobacilli and mutans streptococci and the caries and periodontal status of the subjects. Results: The odds ratio comparing low levels of bacteria in preterm mothers and controls was statistically significant for Lactobacilli (odds ratio (OR) = 3.45, 95% confidence interval (CI) = 1.27 to 10.00) and almost significant for mutans streptococci (OR = 2.63, 95% CI = 0.95 to 8.33). Clinical caries and periodontal disease measures did not differ significantly between groups. Conclusion: Within the limitation of our study, low levels of Lactobacilli in saliva were found to be associated with preterm birth.     

Evaluation of fracture resistance in simulated immature teeth using resilon and ribbond as root reinforcements – An in vitro study

Abstract – Background/Aim: To compare the reinforcement and strengthening ability of resilon, gutta‐percha, and ribbond in endodontically treated roots of immature teeth. Material and Methods: Sixty five freshly extracted human maxillary anterior teeth were prepared with a Peeso no. 6 to simulate immature teeth (Cvek’s stage 3 root development). After instrumentation, each root was irrigated with sodium hypochlorite and with ethylene diamino tetra acetic acid to remove the smear layer. To simulate single visit apexification technique a 4–5 mm white Pro Root mineral trioxide aggregate plug was placed apically using schilder carrier. The teeth were divided into three experimental groups and one control group. Group I – control group (root canals instrumented but not filled); Group II – backfilled with thermoplastisized gutta‐percha using AH plus sealer; Group III – reinforced with Resilon using epiphany sealer; Group IV – reinforced with Ribbond fibers using Panavia F luting cement. A Universal Testing Machine was used to apply a load, at the level of the lingual cementoenamel junction with a chisel‐shaped tip The peak load to fracture was recorded and statistical analysis was completed using student’s t‐test. Results: Values of peak load to fracture were 1320.8, 1604.88, 1620, and 1851newtons for Group I to Group IV respectively. The results of student’s t‐test, revealed no significant difference (P > 0.05,) between Group II and Group III. Comparison between Group IV and Group III and between Group IV and Group II revealed highly significant difference (P > 0.001). Conclusions: Teeth reinforced with Ribbond fibers using Panavia F luting cement showed the highest resistance to fracture. Resilon could not strengthen the roots and showed no statistically significant difference when compared with thermopasticised gutta‐percha in reinforcing immature tooth when tested with universal testing machine in an experimental model of immature tooth.     

Improved hematopoiesis in anemic Sl/Sld mice by splenectomy and therapeutic transplantation of a hematopoietic microenvironment

The ability of a clonal hematopoiesis-supportive bone-marrow stromal cell line GBlneor to engraft and alter the microenvironment-induced anemia of Sl/Sld mice was studied. Prior to stromal cell transplantation, Sl/Sld mice received 1 Gy total body irradiation (TBI) and 13 Gy to the right hind limb. Two months after intravenous (IV) injection of 5 x 10(5) GBlneor cells, 54.4% +/- 17.0% donor origin (G418r) colony-forming cells were recovered from the right hind limb of Sl/Sld mice. Long-term bone marrow cultures (LTBMCs) established from GBlneor-transplanted mice produced 189.5 CFU-GEMM-forming progenitors/flask over 10 weeks compared with 52.7 +/- 6.2 CFU-GEMM forming progenitors/flask from irradiated nontransplanted Sl/Sld mice. A partial correction of macrocytic anemia was detected 2 months after GBlneor transplantation in splenectomized, irradiated Sl/Sld mice (HgB 7.2 +/- 0.4 g/dL; MCV 68.3 +/- 7.0 fL) compared to splenectomized, irradiated, nontransplanted Sl/Sld mice (HgB 5.5 +/- 1.1 g/dL; MCV 76 +/- 8.5 fL) or control Sl/Sld mice (HgB 5.4 +/- 0.5 g/dL; MCV 82.4 +/- 1.3 fL). Mean RBC volume distribution analysis showed a 2.5-fold increase in percentage of peripheral blood RBCs with MCV less than or equal to 45 fL and confirmed reduction of the MCV in splenectomized- GBlneor-transplanted mice compared to control Sl/Sld mice. A hematopoiesis-suppressive clonal stromal cell line derived from LTBMCs of Sl/Sld mice (Sldneor) engrafted as effectively (43.5% +/- 1.2% G418r CFU-F/limb) as did GBlneor cells (38.3% +/- 0.16% G418r CFU-F/limb) to the irradiated right hind limbs of C57Bl/6 mice. LTBMCs established after 2 or 6 months from Sldneor-transplanted mice showed decreased hematopoiesis (182 +/- 12 [2 months] and 3494.3 +/- 408.1 [6 months] CFU-GEMM forming progenitors/flask over 10 weeks) compared to those established from GBlneor-transplanted mice (5980 +/- 530 [2 months] and 7728 +/- 607, [6 months] CFU-GEMM progenitors forming/flask). Thus, transplantation of clonal bone-marrow stromal cell lines in vivo can stably transfer their physiologic properties to normal or mutant mice.