Reduced sensitivity of the ferroportin Q248H mutant to physiological concentrations of hepcidin

Ferroportin Q248H mutation has an allele frequency of 2.2–13.4% in African populations and is associated with a mild tendency to increased serum ferritin in the general population. Some investigators have reported that ferroportin Q248H is degraded after exposure to hepcidin in exactly the same manner as wild-type ferroportin, but supraphysiological concentrations of hepcidin were used. The aim of our study was to determine whether ferroportin Q248H may have reduced sensitivity to physiological concentrations of hepcidin. The sensitivity of ferroportin Q248H to hepcidin was determined in 293T cells transiently expressing ferroportin using immunoblotting and fluorescence analysis. Ferritin concentrations were measured in these cells and also in human primary monocytes derived from humans with different ferroportin genotypes. The effect of Q248H on serum iron measures was examined in patients with sickle cell anemia. Immunoblotting and fluorescence analysis showed decreased sensitivity of ferroportin Q248H to physiological concentrations of hepcidin. Lower ferritin concentrations were observed after incubation with iron and hepcidin in 293T cells expressing ferroportin Q248H and in primary monocytes from ferroportin Q248H subjects. In sickle cell anemia, ferroportin Q248H heterozygotes had lower serum ferritin concentrations than wild-type subjects, consistent with enhanced iron release by macrophage ferroportin Q248H. A clinical benefit of ferroportin Q248H was suggested by lower echocardiographic estimates of pulmonary artery pressure in patients carrying mutant alleles. In conclusion, our results suggest that ferroportin Q248H protein is resistant to physiological concentrations of hepcidin and that this mutation has discernible effects on iron metabolism-related clinical complications of sickle cell anemia. They provide a mechanistic explanation for the effect of ferroportin Q248H on iron status in individuals of African descent and suggest that these changes in iron metabolism may be beneficial under certain disease-specific circumstances.(ClinicalTrials.gov Identifier:{"type":"clinical-trial","attrs":{"text":"NCT00011648","term_id":"NCT00011648"}}NCT00011648).     

National Survey of Clerkship Directors in Internal Medicine on the Competencies That Should Be Addressed in the Medicine Core Clerkship

PURPOSE: To prioritize competencies that should be addressed in the medicine core clerkship, assess factors influencing this prioritization, and estimate the percentage of clerkship time that should be devoted to inpatient versus outpatient care.METHODS: A national survey of the Clerkship Directors in Internal Medicine (CDIM) was used. Using explicit criteria, respondents assigned priority scores, on a 1 to 5 scale, to 17 general competencies and 60 disease-specific clinical competencies pertinent to care of adult patients in inpatient. ambulatory, intensive care, and emergency settings.RESULTS: Ninety-three (75%) of 124 CDIM members responded. The highest mean priority scores were assigned to 6 general competencies: case presentation skills (4.65), diagnostic decision-making (4.64), history and physical diagnosis (4.61), test interpretation (4.47), communication with patients (4.35), and therapeutic decision-making (4.12). Disease-specific clinical competency areas receiving the highest mean priority scores were: hypertension (4.57), coronary disease (4.53), diabetes mellitus (4.45), heart failure (4.42), pneumonia (4.39), chronic obstructive pulmonary disease (4.26), acid-base/electrolyte disorders (4.19), and acute chest pain (4.08). Priorities for general competencies were moderately correlated with importance to the practice of general internists (mean Spearman rho 0.49) and with importance to students pursuing careers outside internal medicine (mean Spearman rho 0.45), but only weakly correlated with the adequacy with which a competency was addressed in other parts of the curriculum. Respondents' mean recommended allocation of clerkship time was: 52% inpatient, 33% ambulatory care, 8% intensive care, and 7% emergency medicine. This time allocation did not differ by any characteristics of respondents.CONCLUSION: There is consensus among medicine clerkship directors that the medicine core clerkship should emphasize fundamental competencies and devote at least one third of the time to clinical competencies pertinent to ambulatory care.     

Combined procoagulant activity and proteolytic activity of acute promyelocytic leukemic cells: reversal of the bleeding disorder by cell differentiation

In the human promyelocytic cell line HL60, we observed both a strong procoagulant activity (PCA) on the cell membrane and proteolytic activity in the lysate of these cells. Because these cell-line cells are susceptible to differentiation to either a more mature granulocytic or monocytic form, we were able to study the hypothesis that the combination of PCA and proteolytic activity is confined to the promyelocyte. This may explain the severe coagulopathy seen in patients with acute promyelocytic leukemia. Cell differentiation in a myeloid direction induced by retinoic acid or DMSO led to a diminished PCA, while not affecting the fibrinolytic activity. On the other hand, monocytic differentiation obtained by culturing the cells in the presence of 1; 25 dihydroxy vitamin D3 led to the complete disappearance of the proteolytic activity of the cell lysate, although the procoagulant activity was still present. Furthermore, we found that the elastase activity almost disappeared after monocytic differentiation. We also studied the PCA, proteolytic activity, and elastase activity of blast cells of patients with acute myeloid leukemia. Only in patients with acute promyelocytic leukemia did we observe both a strong PCA and fibrinolytic activity. This supports our hypothesis that the combination of these activities is unique to the promyelocyte and may explain the observed bleeding complications in patients with acute promyelocytic leukemia.     

Prophylaxis of regional node metastases with liposomes

Experiments on mice showed that local administration of cis-diaminodichloroplatinum incorporated into liposomes inhibited tumor metastases into regional lymph nodes with preserved draining function. When first-order nodes were replaced with tumor tissue, the liposome-incorporated drug inhibited metastasis formation in the second-order lymph nodes (inguinal): it reduced the number and size of metastases in these nodes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 4, pp. 450–451, April, 1999     

Glutathione S-transferase activity in the liver of mice with different sensitivity to hepatocarcinogenic effects ofo-aminoazotoluene

Glutathione S-transferase activity was detected in the liver of inbred mice sensitive (CBA) and resistant (CC57BR and C57B1) to hepatocarcinogenic effects ofo-aminoazotoluene. High liver glutathione S-transferase activity was found in CC57BR and C57B1 and low in CBA mice treated with this carcinogen. Thus, interstrain differences in glutathione S-transferase activity probably determine the resistance too-aminoazotoluene-induced hepatocarcinogenesis. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 2, pp. 174–175, February, 2000     

Study of the antitumor effect of Ukrain: the role of macrophage secretion of alpha-1-proteinase inhibitor

The positive antitumor effect of Ukrain was shown following i.m. injection of a mixture of this drug with Krebs-2 carcinoma cells to CBA mice. The protective effect was suggested to be a result of the influx of macrophages into the site of Ukrain injection. In contrast, contralateral administration of Ukrain had a negative effect, confirming our hypothesis that Ukrain attracts cytolytic macrophages. In the murine HA-1 hepatoma model treated by single or repeated Ukrain injections, a moderate positive effect of Ukrain was related to increased macrophage (alpha-1-proteinase inhibitor (PI) secretion. The role of tumor cells and macrophages in the secretion of PI (the main inhibitor of serine proteinases) during tumor development is discussed.     

Stimulation of Macrophages Increases, While Suppression of These Cells Inhibits Metastatic Dissemination of Two Transplantable Mouse Tumors in the Liver and Lungs

Stimulation of mouse tissue macrophages with carboxymethylated β-(1→3)-D-glycan 1 day before intravenous injection of tumor cells increased the number and weight of implants (experimental metastases) of mouse hepatocarcinoma and adenocarcinoma in the liver and lungs, respectively. Suppression of liver macrophages with gadolinium chloride or sequestration of cells during intraperitoneal administration of macrophage attractants inhibited metastatic dissemination of hepatocarcinoma and adenocarcinoma in the liver and lungs, respectively. In the latter case animal lifespan increased. Our results indicate that at certain stages of metastatic dissemination, activation of mononuclear phagocytes can stimulate the formation and growth of metastases. __________ Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 140, No. 10, pp. 450–452, October, 2005