The efficacy of several endodontic irrigating solutions: a scanning electron microscopic study: Part 2.
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Biomedical subjects
Publications and source records attributed to M Goldman.
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Culture supernatants generated by alloantigenic or lectin stimulation of a cloned helper T lymphocyte, designated L2, contain interleukin 2 (IL 2), granulocyte/macrophage colony-stimulating factor (CSF), B cell stimulating factor (BCSF), macrophage (Ia+)-recruiting factor (MIRF), (Ia+)-inducing activity, gamma-interferon, Fc receptor-enhancing activity, macrophage migration inhibitory factor (MIF), macrophage activation factor (MAF), interleukin 3 (IL 3), and a factor responsible for prolonging the synthesis and secretion of the fourth and second components of complement by guinea pig peritoneal macrophages. Erythropoietin was not detected. A spontaneously arising variant of L2, designated L2V, produces much lower quantities of macrophage-stimulating activities, IL 2, and interferon. However, when compared to L2, L2V produces much higher levels of BCSF, equivalent amounts of IL 3, and slightly smaller amounts of CSF. Unlike L2V, a cytolytic clone, designated L3, secretes lymphokines that primarily affect macrophage function. The time course of lymphokine production by L2 cells indicates that for the six lymphokine activities studied there are three different times at which maximal or near maximal levels are reached, as follows: 1) IL 2, 12 to 24 hr; 2) IL 3 and CSF, 24 to 48 hr; and 3) (Ia+)-inducing activity, MAF, and interferon, 48 hr or later. Only IL 2 activity disappears during the 8-day culture cycle. The time course data and the differential production of activities by the three types of lymphocyte clones suggest that at least four terminal effector lymphokine molecules account for the ten biologic activities tested.
It has been claimed that the neointimal healing of Dacron arterial prostheses can be enhanced by increasing porosity and including both an internal and an external velour layer. To test this, 24 patients received at random either woven (USCI, DeBakey, C. R. Bard, Inc.) or more porous, double-velour, knitted (Microvel, Meadox Medicals, Inc.) Dacron aortobifemoral prostheses. Graft thrombogenicity was measured using autogenous 111In-labeled platelets shortly following surgery and 6 to 9 months later. The thrombogenicity index was defined as the mean daily rise in the ratio of emissions over the graft to emissions over a reference area (aortic arch) and is a measure of platelet deposition. At early study the mean (+/- SE) thrombogenicity index was similar in woven and knitted graft patients at 0.19 +/- 0.4 and 0.14 +/- 0.2, respectively. In both groups it was lower (P less than 0.05) 6 to 9 months later at 0.06 +/- 0.2 (woven( and 0.08 +/- 0.1 (knitted), with again no difference between materials. Although platelet survival was restored to near normal values in both groups by 6 to 9 months, only one woven graft failed to demonstrate continued platelet accumulation by gamma-imaging. Thrombogenicity in Dacron grafts diminishes in the early months of maturation but is not affected by porosity and velour. Moreover, this thrombogenicity persists beyond the period of altered platelet survival.
Penetrating ionizing radiation fairly uniformly puts all exposed molecules and cells at approximately equal risk for deleterious consequences. Thus, the original deposition of radiation energy (that is, the dose) is unaltered by metabolic characteristics of cells and tissue, unlike the situation for chemical agents. Intensely ionizing radiations, such as neutrons and alpha particles, are up to ten times more damaging than sparsely ionizing sources such as x-rays or gamma rays for equivalent doses. Furthermore, repair in cells and tissues can ameliorate the consequences of radiation doses delivered at lower rates by up to a factor of ten compared with comparable doses acutely delivered, especially for somatic (carcinogenic) and genetic effects from x- and gamma-irradiation exposure. Studies on irradiated laboratory animals or on people following occupational, medical or accidental exposures point to an average lifetime fatal cancer risk of about 1 x 10(-4) per rem of dose (100 per 10(6) person-rem). Leukemia and lung, breast and thyroid cancer seem more likely than other types of cancer to be produced by radiation. Radiation exposures from natural sources (cosmic rays and terrestrial radioactivity) of about 0.1 rem per year yield a lifetime cancer risk about 0.1 percent of the normally occurring 20 percent risk of cancer death. An increase of about 1 percent per rem in fatal cancer risk, or 200 rem to double the "background" risk rate, is compared with an estimate of about 100 rem to double the genetic risk. Newer data suggest that the risks for low-level radiation are lower than risks estimated from data from high exposures and that the present 5 rem per year limit for workers is adequate.
Mouse mammary tissues, including ducts, prelactating lobules, hyperplastic outgrowth lines, and tumors, were exposed to varying doses of X-rays and then transplanted to fat pads of nonirradiated BALB/c mice for study. Estimates of the dose of radiation that would allow survival of 50% of the transplants (SD50) were made with the use of probit analysis. Nearly all duct and lobule transplants survived doses of X-rays from 0 to 800 rad. The survival rate declined rapidly following doses above 800 rad, and the calculated SD50 was 1,020 and 1,260 rad for mammary ducts and lobules, respectively. The three hyperplastic outgrowth lines tested gave very different results. Hyperplastic line Z5C1 transplants had better than 90% survival at doses up to 1,200 rad and an SD50 between 1,200 and 1,600 rad. Hyperplastic line Z5D transplants had an SD50 of between 800 and 1,200 rad. Hyperplastic line D1 transplants had a better than 90% survival following doses of 0-600 rad and an SD50 between 600 and 800 rad. The survival of tumor transplants was 100% following doses of X-rays up to 1,200 rad; the SD50 was in excess of 1,600 rad. The mouse mammary transplantation system can be used to study the direct effect of X-rays on normal, premalignant, and malignant mammary tissues and provides a basis for the study of the radiobiology of mammary tissues.
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IgG antibody responses to a major allergen, cat allergen 1 (cat 1), and to a minimally allergenic protein, cat albumin (alb), were studied in patients who had received 4 to 11 mo of immunotherapy with three concentrations of crude cat pelt extract. A double-antibody radioimmunoassay utilizing 125I-labeled antigen was used to measure IgG and IgE antibody. The high-dose group (HDG)(n = 5), which was composed of the active-treatment group of a previously reported double-blind study, received a mean cumulative dose of 3440 microgram cat 1 and 10,660 microgram alb. The intermediate-dose group (IDG) (n = 6) and low -dose group (IDG)(n = 5) received 70 and 0.930 microgram of cat 1 and 217 and 2.86 microgram of alb. IgE antibody to cat 1 before treatment was measurable in most patients. IgE antibody to alb was either no measurable or of a low level. Mean (geometric) before-and-after IgG levels (U/ml) to cat 1 in the HDG, IDG, and LDG were 420 and 7794, 158 and 1388, an 191 and 1365, respectively. Mean before-and-after IgG levels (U/ml) to alb in the HDG, IDG, and LDG were 72 and 348, 1.9 and 4584, and 0.4 and 508, respectively. Two patients (HDG) had no IgG antibody to alb after treatment. Another patient (HDG) had 82,364 U/ml IgG antibody to alb and precipitating antibody by gel diffusion. Very intense IgG antibody response to both cat 1 and alb were seen over a wide range of immunizing doses.
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Lead shot recovered at necropsy 2 and 3 weeks after being dropped down the throats of Pekin ducklings caused significant increases in thyroid gland weight and 24-hr thyroid uptake of 125I while serum PB125I levels were maintained at or above control values. Supplementation of lead shot with 1 ppm selenium in drinking water reduced these increases. Selenium in the drinking water incurred no increase in thyroid gland weight at 2 weeks but some goitrogenicity at 3 weeks and significant reductions in thyroid radioiodine uptake and serum PB125I levels at 2 and 3 weeks. Chromatographic analyses of thyroid hydrolysates demonstrated a depression in iodothyronine (T4 and T3) labeling in lead shot-treated and selenium-treated animals which was corrected by addition of selenium to lead shot-treated ducklings. These findings indicate that while either lead or selenium treatment, independently, exerts a selective toxic effect on thyroid function, selenium supplementation of lead-treated Pekin ducklings does protect against the toxicity of lead on thyroid function.
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