G6PD San Francisco: a new variant of glucose-6-phosphate dehydrogenase associated with congenital nonspherocytic hemolytic anemia

Congenital nonspherocytic hemolytic anemia in an adult male of Scandinavian ancestry was associated with virtual absence of G6PD activity in red cells. Characterization of G6PD purified from leukocytes using standard WHO techniques revealed diminished electrophoretic mobility, marked lability on heating at 46 degrees C, normal pH optimum and utilization of alternate substrates (2-deoxy G6P, D-amino NADP), elevated Km NADP, and striking susceptibility to NADPH inhibition. The variant G6PD, which appears to be unique, has been designated G6PD San Francisco. An unusual feature of the variant enzyme, susceptibility to inactivation by brief periods of dialysis, could be prevented by addition of 200 microM NADP to the dialysis solution. In red cells, where G6PD activity was essentially absent, regeneration of reduced glutathione was totally curtailed in vitro, while in leukocytes, where residual G6PD activity was approximately 60% of normal, hexose monophosphate shunt activity, oxygen consumption during phagocytosis, and bacterial killing were unimpaired. Thus, instability of the variant enzyme rather than its unfavorable kinetics appeared to be an important determinant of abnormal cell function.     

Transforming growth factor-beta 1 cooperates with anti-immunoglobulin for the induction of apoptosis in group I (biopsy-like) Burkitt lymphoma cell lines

Group I Burkitt lymphoma (BL) cell lines, which retain the original biopsy phenotype, have been shown to enter apoptosis in response to a number of external stimuli including serum deprivation, thermal shock, addition of calcium ionophore, and ligation of surface immunoglobulin (Ig) by antibody. Transforming growth factor-beta 1 (TGF beta 1) is known to cause growth arrest in BL lines. Here we show that while it is by itself capable of promoting some degree of apoptosis in group IBL cells, TGF beta 1 cooperates with anti-immunoglobulin to this end. Trimeric soluble recombinant human CD40 ligand (sCD40L) was able to inhibit apoptosis induced by the combination of agonists to some degree, but such rescue proved to be short-lived. Both TGF beta 1 and anti-Ig individually caused BL cells to undergo growth arrest at the G1 phase of cell cycle before their entry into apoptosis: the consequence of sCD40L addition was to maintain the cells in cycle for longer. No induction of the apoptosis-protecting gene, bcl-2, occurred in the presence of sCD40L. These findings are discussed, particularly highlighting the relationship existing between survival and the cell cycle. The strong cooperative effects observed between anti-Ig and TGF beta 1 in promoting apoptosis and the inability of CD40 to signal for long-term rescue raise the potential for a novel therapeutic attack on B-cell lymphoma.     

Moderation of hemophilia A phenotype by the factor V R506Q mutation

Although many examples of unrelated hemophilia A patients carrying identical point mutations in the factor VIII (FVIII) gene have been reported, the clinical phenotype is not always the same among patients sharing the same molecular defect. Possible explanations for this discrepancy include undetected additional mutations in the FVIII gene or coinheritance of mutations at other genetic loci that modulate FVIII function. We report molecular genetic analysis of potential modifying genes in two sets of unrelated patients carrying common FVIII missense mutations but exhibiting different levels of clinical severity. Both mutations (FVIII R1689C and R2209Q) are associated with severe hemophilia A in some patients and mild/moderate disease in others. The common von Willebrand disease type 2N mutation (R91Q) was excluded as a modifying factor in these groups of patients. However, analysis of the recently described factor V (FV) R506Q mutation (leading to activated protein C resistance) identified a correlation of inheritance of this defect with reduced hemophilia A severity. Two moderately affected hemophilia A patients, each with either of two FVIII gene mutations, were heterozygous for FV R506Q, whereas two severely affected patients and two moderately affected patients were homozygous normal at the FV locus. Our results suggest that coinheritance of the FV R506Q mutation may be an important determinant of clinical phenotype in hemophilia A and that modification of the protein C pathway may offer a new strategy for the treatment of FVIII deficiency.     

Heterogeneity of large granular lymphocyte proliferations: delineation of two major subtypes

Two major types of lymphocytosis of large granular lymphocytes (LGLs) were observed. The proliferating LGLs in each type had distinct immunophenotypes, functional characteristics, and probably belonged to different cell lineages. The more common form (Type A) consisted of cells derived from the T cell lineage and had the T suppressor/cytotoxic phenotype (T11+, T3+, T8+). The expression of the Leu 7 and HLA-DR antigen was variable. These cells did not have natural killer (NK) function but showed a variable degree of antibody-dependent cell-mediated cytotoxic (ADCC) activity. Neutropenia was invariably present and rheumatoid arthritis and autoantibodies were frequent associations. These lymphocytes had many similarities to the major type of LGLs present in normal adult bone marrow. The other type of LGL lymphocytosis (Type B) consisted of cells lacking the antigens T3 and T8 but expressing M1 and NKH1. These cells possessed strong NK and ADCC activity but their cell lineage was not clear. Neutropenia and autoimmune phenomena were not detected. The cytochemical characteristics of the LGL granules from both types of patients were similar but differences in ultrastructure were observed. LGLs from Type B patients proliferated in the presence of Interleukin 2 (IL-2) and 12- O-tetradecanoyl-phorbol-13 acetate (TPA). Significant changes in their basic T11+, T3-, T8- phenotype were not observed. IL-2 and TPA, however, had profound influence on the NK function of the cells with enhancement in the case of IL-2 and marked suppression when stimulated by TPA.     

Dietary Diabetes Risk Reduction Score,Race and Ethnicity,and Risk of Type 2 Diabetes in Women

OBJECTIVE

To evaluate racial and ethnic differences in the association between a dietary diabetes risk reduction score and incidence of type 2 diabetes in U.S. white and minority women.

RESEARCH DESIGN AND METHODS

We followed 156,030 non-Hispanic white (NHW), 2,026 Asian, 2,053 Hispanic, and 2,307 black women in the Nurses’ Health Study (NHS) (1980–2008) and NHS II (1991–2009). A time-updated dietary diabetes risk reduction score (range 8–32) was created by adding points corresponding with each quartile of intake of eight dietary factors (1 = highest risk; 4 = lowest risk). A higher score indicates a healthier overall diet.

RESULTS

We documented 10,922 incident type 2 diabetes cases in NHW, 157 in Asian, 193 in Hispanic, and 307 in black women. Multivariable-adjusted pooled hazard ratio across two cohorts for a 10th–90th percentile range difference in dietary diabetes risk reduction score was 0.49 (95% CI 0.46, 0.52) for NHW, 0.53 (0.31, 0.92) for Asian, 0.45 (0.29, 0.70) for Hispanic, 0.68 (0.47, 0.98) for black, and 0.58 (0.46, 0.74) for overall minority women (P for interaction between minority race/ethnicity and dietary score = 0.08). The absolute risk difference (cases per 1,000 person-years) for the same contrast in dietary score was −5.3 (−7.8, −2.7) for NHW, −7.2 (−22.9, 8.4) for Asian, −11.6 (−26.7, 3.5) for Hispanic, −6.8 (−19.5, 5.9) for black, and −8.0 (−15.6, −0.5) for overall minority women (P for interaction = 0.04).

CONCLUSIONS

A higher dietary diabetes risk reduction score was inversely associated with risk of type 2 diabetes in all racial and ethnic groups, but the absolute risk difference was greater in minority women.     

SMS-based smartphone application for disease surveillance has doubled completeness and timeliness in a limited-resource setting – evaluation of a 15-week pilot program in Central African Republic (CAR)

Background

It is a challenge in low-resource settings to ensure the availability of complete, timely disease surveillance information. Smartphone applications (apps) have the potential to enhance surveillance data transmission.

Methods

The Central African Republic (CAR) Ministry of Health and Médecins Sans Frontières (MSF) conducted a 15-week pilot project to test a disease surveillance app, Argus, for 20 conditions in 21 health centers in Mambéré Kadéi district (MK 2016). Results were compared to the usual paper-based surveillance in MK the year prior (MK 2015) and simultaneously in an adjacent health district, Nana-Mambére (NM 2016). Wilcoxon rank sum and Kaplan-Meier analyses compared report completeness and timeliness; the cost of the app, and users’ perceptions of its usability were assessed.

Results

Two hundred seventy-one weekly reports sent by app identified 3403 cases and 63 deaths; 15 alerts identified 28 cases and 4 deaths. Median completeness (IQR) for MK 2016, 81% (81–86%), was significantly higher than in MK 2015 (31% (24–36%)), and NM 2016 (52% (48–57)) (p?<?0.01). Median timeliness (IQR) for MK 2016, 50% (39–57%) was also higher than in MK 2015, 19% (19–24%), and NM 2016 29% (24–36%) (p?<?0.01). Kaplan-Meier Survival Analysis showed a significant progressive reduction in the time taken to transmit reports over the 15-week period (p?<?0.01). Users ranked the app’s usability as greater than 4/5 on all dimensions. The total cost of the 15-week pilot project was US$40,575. It is estimated that to maintain the app in the 21 health facilities of MK will cost approximately US$18,800 in communication fees per year.

Conclusions

The app-based data transmission system more than doubled the completeness and timeliness of disease surveillance reports. This simple, low-cost intervention may permit the early detection of disease outbreaks in similar low-resource settings elsewhere.

     

Eleven novel mutations in the factor VIII gene from Brazilian hemophilia A patients

The molecular characterization of the mutations in hemophilia A patients is hampered by the large size of the factor VIII gene and the great heterogeneity of mutations. In this study, we have performed a protocol involving multiplex polymerase chain reaction in which 19 exons were amplified in four different combinations followed by nonradioactive single-strand conformational polymorphism (SSCP) to screen for mutations. Southern blotting was used to detect inversion of the factor VIII gene resulting from recombination between copies of the gene A (F8A) located in intron 22 of the factor VIII gene and two copies close telomeric region of X chromosome. Forty-two hemophilia A patients (21 with severe and 21 with mild-to-moderate disease) were studied. The inversion of factor VIII occurred in 13 of 21 patients affected by severe hemophilia A. One patient showed a large extra band in addition to the three bands observed after Southern blotting with the F8A probe. An abnormal electrophoretic pattern of SSCP was detected in 85% and 50% of the patients affected by mild-to-moderate and severe disease, respectively. Sixteen different mutations were identified. Eleven mutations were novel and comprised 9 point mutations and 2 small deletions. This study shows that the methodology used is safe and rapid and has potential for detecting almost all of the genetic defects of the studied hemophilia A patients.