Reduced thymocyte proliferation but not increased apoptosis as a possible cause of thymus atrophy in iron-deficient mice.

Iron deficiency induces thymus atrophy in laboratory animals and very likely in humans by unknown mechanisms. The atrophy is associated with impaired cell-mediated immunity. In this study, we tested the hypothesis that thymus atrophy is a result of increased apoptosis and reduced thymocyte proliferation. Thymocytes were obtained from twenty-seven control, twenty-seven pairfed, twenty-seven iron-deficient (ID) mice; twelve and fourteen ID mice that received the control diet (0.9 mmol/kg versus 0.09 mmol/kg for the ID diet) for 1 d (repletion, R1) and 3 d (R3), respectively. Cell cycle analysis and apoptosis were studied by flow cytometry using propidium iodide staining and terminal deoxyuridine nick end labeling of DNA breaks assay respectively. When mice were killed, haemoglobin, haematocrit, and liver iron stores of ID, R1, and R3 mice were 25-40 % of those of control and pairfed mice Absolute and relative thymus weights and thymocyte numbers were 19 to 68 % lower in ID, R1, and R3 than in control and pairfed groups We found no significant difference among groups in the percentage of cells undergoing apoptosis. A higher percentage of thymocytes from ID and R1 mice than those of control, pairfed, and R3 mice were in the resting phase of the normal cell cycle Conversely, a lower percentage of thymocytes from ID and R1 mice than those from control, pairfed, and R3 mice were in the DNA synthesis phase and late phase of DNA synthesis and onset of mitosis (G2-M) Indicators of iron status positively correlated (r 0.3 to 0.56) with the percentage of thymocytes in the G2-M phase Results suggest that reduced cell proliferation but not increased apoptosis is the cause of thymus atrophy associated with iron deficiency.

Iron deficiency alters the progression of mitogen-treated murine splenic lymphocytes through the cell cycle.

The influence of iron deficiency on the progression of mitogen-treated splenic lymphocytes through the cell cycle was studied in 16 control, 16 pair-fed, 15 iron-deficient (ID) and 16 ID mice that were repleted for up to 3 d (R3). The test and control diets differed only in iron concentrations (0.09 vs. 0.9 mmol/kg). When mice were killed (68 d of feeding), the hemoglobin concentration and liver iron stores of ID and R3 mice were <50% those of control mice (P < 0.05). Iron deficiency did not reduce the percentage of CD3(+) cells, but decreased CD3(+) cells/mg spleen (P < 0.05). In concanavalin A-treated and nonactivated cultures, there were no significant differences among groups in the percentages of cells in resting phase of the cell cycle (G0) to cell cycle initiation phase (G1), DNA synthesis phase (S) and exit from the S phase (G2) to mitosis phase (M) phases. In anti-CD3 and anti-CD3/anti-CD28-treated cultures, higher percentages of lymphocytes from ID and R3 mice than those from control and pair-fed mice were in the G0--G1 phase (P < 0.05). Conversely, lower percentages of activated cells from ID and R mice than those from control and pair-fed mice were in S and G2--M phases (P < 0.05). Incubation of lymphocytes with mitogens decreased the percentages of cells in G0--G1 phase from 90% to 80% in control and pair-fed but not in ID and R3 mice (P < 0.05). In activated cells, indices of iron status negatively correlated with the percentages of cells in G0--G1 (r = -0.306 to -0.597) but positively with those in S (r = 0.166--0.511) and G2--M phases (r = 0.265-0.59; P < 0.05). Data suggest that altered cell cycle progression likely contributes to impaired lymphocyte proliferation usually associated with iron deficiency.

Cemented total hip arthroplasty with Boneloc bone cement.

Boneloc cement (WK-345, Biomet Inc, Warsaw, Ind) attempted to improve cement characteristics by reducing exotherm during polymerization, lowering residual monomer and solubility, raising molecular weight, and lowering airborne monomer and aromatic amines. To study the efficacy of this cement, a selected group of 20 patients were prospectively enrolled and followed up after hip arthroplasty. All components were cemented. During the enrollment period, approximately 70 other hip arthroplasties were performed. Clinical evaluation was based on the Harris hip score. Radiographic evaluation was based on assessment of position of the components, subsidence, and/or presence of radiolucencies. Patients had follow-up for an average of 42 months (11 to 58 months); 1 was lost to follow-up. Of these, 7 (35%) had failure at last follow-up. Despite its initial promise, Boneloc cement had an unacceptably high failure rate over a relatively short follow-up period and is not recommended for use. Despite the longevity and odor toxicity problems with conventional bone cement, new cement technologies must be approached with caution.

Purification of murine pulmonary type II cells for flow cytometric cell cycle analysis.

Mice are widely used as animal models for in vivo lung disease. Despite this fact, few methods exist for isolation of type II pneumocytes from mouse lung, limiting the study of alveolar epithelial characteristics in these models. This study investigated several methods for labeling murine lung cell suspensions for flow cytometric identification and sorting of type II pneumocytes. Crude lung cell suspensions were prepared after intratracheal instillation of Dispase and were labeled using phosphine alone or in combination with Helix pomatia lectin, Maclura pomifera lectin, or anti-murine-CD32. Crude cell suspensions yielded 17.4 million cells per animal with 19.5% type II pneumocytes by Pap staining. Ultrastructural evaluation of the sorted cell pellets (1-1.5 million cells each) demonstrated optimal type II cell purity in preparations labeled with phosphine and anti-CD32 (94.3% type II cells, 0.4% macrophages, 2.8% Clara cells, and 2.5% other). Nuclear suspensions appropriate for cell cycle analysis were produced by sorting the type II cells directly into hypotonic propidium iodide, and these preparations clearly demonstrated a substantial increase in S-phase type II cells during proliferative repair of BHT-induced acute lung injury.