Hyperhomocysteinemia and cobalamin deficiency in young Asian Indians in the United States

Hyperhomocysteinemia, a risk factor for vascular disease, may be a particular problem in Asian Indians, but information is limited, especially in the U.S., despite its growing Asian population. Moreover, suggestions have been made that folate deficiency is responsible for the hyperhomocysteinemia in Indians. Therefore, we studied homocysteine status in healthy Asian Indians in the U.S. prospectively, determined the frequency of cobalamin and folate deficiency as contributors to it, and examined whether food-cobalamin absorption contributed to cobalamin deficiency. Homocysteine levels were higher in Asian Indian men than in 4 other ethnic groups (P < 0.0001); 10/39 Indian men (25.6%) were hyperhomocysteinemic. Cobalamin levels were lower in Indian men (P = 0.000005) and women (P = 0.03) than in non-Indians; low levels were found more frequently in both Indian men (23/39; 59.0%) and women (5/21; 23.8%) than in others. Measuring methylmalonic acid in 10 selected subjects showed that the low cobalamin levels reflected cobalamin deficiency, and high methylmalonic acid levels were found in some subjects without hyperhomocysteinemia. Evidence of folate deficiency was not found in any subjects. Food-cobalamin absorption was normal in all 13 Indian subjects tested, including those with Helicobacter pylori infection. The results show that hyperhomocysteinemia is strikingly common in apparently healthy, young Asian Indian men. The cause appears to be cobalamin deficiency, which affected more than half of the Indian men, may be largely subclinical, is underestimated by homocysteine levels alone which were not always abnormal, and is probably largely dietary in origin. Folate deficiency is rare. This public health problem is amenable to prevention and treatment in this growing segment of the U.S. population. It was, parenthetically, noteworthy that many of the affected subjects were young physician trainees.     

Dependency on intercellular adhesion molecule recognition and local interleukin-2 provision in generation of an in vivo CD8+ T-cell immune response to murine myeloid leukemia

The immune response to a murine myeloid leukemia (cell line C1498) was studied in vitro and in vivo. Natural killer (NK) cells and CD8+ cytotoxic T lymphocytes (CTL) were shown to lyse C1498 in vitro through the binding of leukocyte function antigen-1 (LFA-1) on effectors and intercellular adhesion molecule-1 (ICAM-1) and ICAM-2 on C1498 target cells. However, the ability of nonimmunized mice to resist an in vivo challenge of a low dose (10(4)) of C1498 was NK-cell, but not T-cell dependent. The failure of T cells to participate in the immune surveillance of a low leukemia burden appeared, in part, because of a lack of expansion of leukemia reactive CTL precursors (CTLp). Leukemia reactive CTLp frequency estimations in naive and leukemia bearing mice were not significantly different (range, 1:20,600 to 1:74,000) in contrast to immunized mice (range, 1:1,400 to 1:4,400). Leukemia reactive CTLp could be expanded to a level that could apparently mediate in vivo immune surveillance of 10(5) leukemia cells by injection of irradiated leukemia cells intraperitoneally (IP) or subcutaneously (SC), but not intravenously (IV). However, IV injection of 10(5) live leukemia cells engineered to secrete interleukin-2 (IL-2) resulted in systemic immunity mediated primarily by CD8+ T cells. We conclude that NK cells can mediate immune surveillance of a low leukemia burden. CD8+ CTL-mediated immune surveillance can eliminate a higher leukemia burden than NK cells, but requires T-cell help, which can be delivered by local IL-2. Both NK and CTL-mediated immune surveillance of C1498 murine myeloid leukemia is dependent on recognition through the LFA-1:ICAM adhesion pathway.     

Granulocyte colony-stimulating factor "mobilized" peripheral blood progenitor cells accelerate granulocyte and platelet recovery after high-dose chemotherapy

Hematopoietic growth factors have been used to accelerate engraftment after bone marrow transplantation and to "mobilize" peripheral blood progenitor cells (PBPC). We report on the data in 85 consecutive patients with Hodgkin's disease who were treated in a single institution using different methods to obtain PB progenitor cells. Use of granulocyte colony-stimulating factor for mobilization resulted in a significantly accelerated time to recovery of granulocytes (10 days v 12 days, P < .01) when compared with "nonmobilized" PBPC recipients. Similarly, use of mobilized PBPC resulted in a significantly accelerated time to platelet engraftment (13 days v 30 days, P < .001) when compared with "nonmobilized" recipients. Moreover, there was a statistically significant difference in total costs in favor of the group receiving "mobilized" PBPC.     

Regulation of early human hematopoietic (BFU-E and CFU-GEMM) progenitor cells in vitro by interleukin 1-induced fibroblast-conditioned medium

Stimulators of human erythroid burst-forming units (BFU-E) and multipotential colony-forming cells (CFU-GEMM) can be produced by a number of different cell types. A product of human peripheral blood monocytes, interleukin 1 (IL-1), was evaluated for its ability to stimulate fibroblast cultures to produce stimulators of human bone marrow BFU-E and CFU-GEMM colony formation. BFU-E and CFU-GEMM colony formation was evaluated using low-density, nonadherent low-density, and T lymphocyte-depleted nonadherent low-density human bone marrow cells cultured in the presence of a source of pure human erythropoietin. Both human monocyte conditioned medium (MCM) and human recombinant IL-1 (hrIL-1) induced fibroblasts to produce stimulators of BFU-E and CFU- GEMM in a dose-dependent fashion with maximal colony formation occurring when fibroblasts were stimulated by 25% MCM or 140 ng/mL ROO6B hrIL-1, or 1.25 to 5 ng/mL ROO6T hrIL-1. Preincubation of MCM and hrIL-1 with an antibody to IL-1 inactivated the ability of MCM and hrIL- 1 to induce the release of erythroid and multipotential colony stimulating activity from fibroblasts. These results suggest that monocyte-derived IL-1 is involved in regulating the production of humoral stimulators of early human hematopoietic progenitors.     

The effect of the plasticizer di(2-ethylhexyl)phthalate on red cell deformability

Red cell concentrates (RCC) are stored for 35 to 42 days in plastic containers manufactured with the liquid plasticizer di(2- ethylhexyl)phthalate (DEHP). DEHP leaches from the polyvinylchloride (PVC) plastic bag, then binds to and stabilizes the RC membrane. This study was undertaken to determine the deformability of the RC membrane using an osmotic gradient ektacytometer and to relate these measurements to the concentration of DEHP in the stored RCC. Pooled RCC was aliquoted into PL146 (PVC), PL732 (polyolefin), and PL732 (with added DEHP) bags with samples removed weekly for analysis of osmotic fragility, deformability, and DEHP concentration. The adenosine triphosphate (ATP) content was also measured. The increase in osmotic fragility during storage was greater when RCC was stored without DEHP. In addition, there was a decrease in the maximum elongation index (El max) when there was decreased DEHP in the storage bag. The osmolarity (Omax) at which El max occurred, as well as the Omin, the osmolarity at which minimum elongation (El min) occurred was higher in the PL732 container than in the PL146 or in the PL732 to which DEHP had been added. These changes could be reversed by addition of DEHP at the beginning of the storage period, showing a direct correlation between DEHP concentration during storage and RC membrane flexibility. By a better understanding of the mechanism of DEHP protection, it might be possible to substitute a less toxic stabilizing compound.     

Protection of mice from lethal doses of methotrexate by transplantation with transgenic marrow expressing drug-resistant dihydrofolate reductase activity

Marrow cells from previously established lines of transgenic mice expressing either of two different methotrexate (MTX)-resistant dihydrofolate reductases (DHFRs) were transplanted into recipient animals to determine the resultant in vivo protective effect against toxicity associated with MTX administration. Sublethally irradiated, untransplanted animals were first used to establish conditions of low- dose MTX administration resulting in substantial hematopoietic toxicity with undetectable gastrointestinal toxicity. Under these conditions, low survival rates were observed for normal or transgenic animals not expressing drug-resistant DHFR activity, whereas transgenic animals expressing either the arg22 (line 04) or trp31 (line 03) DHFR variants survived. Transplantation of 10(6) marrow cells from either transgenic lines 03 or 04 rescued normal FVB/N recipient animals from low-dose MTX administration, which was lethal for animals transplanted with 10(6) normal FVB/N marrow cells. Reduced survival of transgenic line 04 marrow recipients was observed when twofold or fourfold doses of MTX were administered. However, when 10(7) transgenic line 04 marrow cells were infused, the recipients were found to be resistant to a MTX dose that was not only lethal for animals transplanted with 10(7) normal FVB/N marrow cells, but also lethal for normal, untransplanted FVB/N mice. Histologic analysis showed protection of both marrow and gastrointestinal tissues from MTX toxicity in transgenic line 04 marrow transplant recipients. Thus, exclusive expression of MTX-resistant DHFR activity in the marrow had a substantial, systemic chemoprotective effect in animals, which could be applied for improved utilization of MTX for antitumor chemotherapy.     

Biosynthesis of human growth hormone-releasing hormone (hGRH) in the pituitary of hGRH transgenic mice

We have studied the posttranslational processing of prohuman GH-releasing hormone (pro-hGRH) to the mature hormones, hGRH(1-44)-NH2 and hGRH(1-40)-OH, and its carboxyl-terminal peptide (hGCTP) in pituitary cells from transgenic mice bearing a metallothionein-hGRH fusion gene after incubation with [35S]methionine. After separation on HPLC, 35S-labeled and unlabeled hGRH in medium and cell extracts were characterized by RIA and immunoprecipitation with antisera against hGRH and against hGCTP. After a 4-h pulse, unlabeled and [35S]pro-hGRH, hGRH(1-44)-NH2, and hGRH(1-40)-OH were identified in medium and cell extracts by both RIA and immunoprecipitation with anti-hGRH serum. In cell extracts, after a 0.5-h pulse, [35S]pro-hGRH and hGRH(1-44)-NH2 but not [35S]hGRH(1-40)-OH were detectable. After a 0.5-h chase, however, 35S-labeled hGRH(1-40)-OH, pro-hGRH, and [35S]hGRH(1-44)-NH2 were all measurable. After a 4-h chase, comparable levels of [35S]hGRH(1-44)-NH2 and hGRH(1-40)-OH were present, and very little intracellular 35S-pro-hGRH remained. A progressive decrease in the ratio of immunoprecipitable pro-hGRH to mature hGRH peptides and an increase in the ratio of hGRH(1-40)-OH to hGRH(1-44)-NH2 was observed in the two chase periods. In medium, [35S]hGRH(1-44)-NH2 was detectable at all times, whereas only minimal amounts of [35S]hGRH(1-40)-OH were present. Labeled and unlabeled pro-hGRH in cell extracts was also detected with anti-hGCTP serum, and another peak, which coeluted with synthetic hGCTP, was also identified. The low molar ratio of intracellular immunoreactive hGCTP to hGRH (less than 0.02) suggests a more rapid turnover rate of hGCTP than of hGRH. These results demonstrate the processing of hGRH prohormone to both mature forms of hGRH and provide evidence that hGRH(1-40)-OH is derived from hGRH(1-44)-NH2.     

Predictors of mortality in a cohort of intensive care unit patients with acute renal failure receiving continuous renal replacement therapy

BACKGROUND: Despite the frequent use of continuous renal replacement therapy (CRRT) in the management of acute renal failure (ARF) in the critically ill, predictors of mortality remain unclear. METHODS: A registry of all patients initiated on CRRT at a single institution was assembled over an 18-month period, and a subsequent cross-sectional analysis of selected variables was conducted for associations with mortality. Predictors evaluated were age, gender, diagnosis of sepsis, Apache II score, days between ARF diagnosis and initiation of CRRT, creatinine at initiation of CRRT, change in creatinine from baseline and admission to initiation of CRRT, setting of ARF, and prescribed CRRT dose. The principal outcome was mortality at 30 days. RESULTS: Eighty-one individuals met inclusion criteria. Overall mortality for the study was 50.2%. The mean elevation in creatinine from admission to initiation of CRRT was 1.6 mg/dL (141.4 micromol/L) in those who lived and 2.6 mg/dL (229.8 micromol/L) in those who died (P = 0.023). Patients admitted with normal renal function who developed ARF while in the hospital had mortality of 56.3%. When available, patients with abnormal renal function at presentation were further classified by either abnormal or normal preadmission creatinine. These patients had mortality of 31.3% and 83.3%, respectively. These differences in mortality were statistically significant. CONCLUSIONS: Increased mortality was significantly associated with the magnitude of change in serum creatinine between admission and initiation of CRRT. Also, patient ARF classification was significantly associated with mortality.     

Efficacy and safety of biological agents in the older rheumatoid arthritis patients compared to Young: A systematic review and meta-analysis

Objective

Biologic anti-rheumatic drugs are used with less frequency among older patients compared to young patients. This population is less represented in studies performed to evaluate the efficacy and safety of this drugs. We aimed to assess the efficacy and safety of biological agents between the older RA patients compared to young.