A novel CD93 polymorphism in non-obese diabetic (NOD) and NZB/W F1 mice is linked to a CD4+ iNKT cell deficient state

In the present study, we characterize a polymorphism in the CD93 molecule, originally identified as the receptor for the C1q complement component (i.e., C1qRp, or AA4.1) in non-obese diabetic (NOD) mice. This allele carries a coding polymorphism in the first epidermal growth factor-like domain of CD93, which results in an amino acid substitution from Asn→His at position 264. This polymorphism does not appear to influence protein translation or ecto-domain cleavage, as CD93 is detectable in bone-marrow-derived macrophage and B-cell precursor lysates and in soluble form in the serum. The NOD CD93 isoform causes a phenotypic aberrancy in the early B-cell developmental stages (i.e., pro-, pre-, immature, and transitional), likely related to a conformational variation. Interestingly, the NZB/W F1 strain, which serves as a murine model of Lupus, also expresses an identical CD93 sequence polymorphism. Cd93 is located within the NOD Idd13 locus and is also tightly linked to the NZB/W F1 Wbw1 and Nkt2 disease susceptibility loci, which are thought to regulate natural killer T (NKT) cell homeostasis. Consistent with this genetic linkage, we found B6 CD93^−/− and B6.NOD^Idd13 mice to be susceptible to a profound CD4⁺ NKT cell deficient state. These data suggest that Cd93 may be an autoimmune susceptibility gene residing within the Idd13 locus, which plays a role in regulating absolute numbers of CD4⁺ NKT cells.     

Anaemia,Zinc and Copper Deficiencies Among Pregnant Women in Central Sudan

Anaemia is a widespread problem in many parts of the world especially in tropic areas. Among pregnant women, it has negative consequences on maternal and perinatal outcomes. A cross-sectional study was conducted to investigate the prevalence of anaemia, iron, zinc and copper deficiencies among pregnant women in Wad Medani hospital, central Sudan and to examine the relationship of these micronutrients with haemoglobin (Hb) levels. One hundred four (52.5%) out of 200 pregnant women had anaemia (Hb < 11 gm/dl) and 3 (1.5) % had severe anaemia (Hb < 7 gm/dl). Iron deficiency (S-ferritin < 15 μg/l), iron deficiency anaemia (<11 gm/dl and S-ferritin < 15 μg/l) were prevalent in 25 (12.5%) and 13 (6.5%) of these women, respectively. Ninety (45.0%) and eight (4.0%) of these women had zinc (<80 μg/ml) and copper (<80 μg/ml) deficiency, respectively. In 24 (12.0%) of these women, there were ≥2 deficiencies of these elements. S-copper was significantly lower in patients with anaemia. While age, parity, gestational age, ferritin, zinc and copper were not predictors for anaemia, women who practiced pica were at higher risk for anaemia (OR = 3.4, 95% CI = 1.4–7.9, P = 0.004). Gestational age was significantly inversely correlated with haemoglobin (r = 0.161, P = 0.03), S-ferritin (r = 0.285, P = 0.001) and S-zinc (r = 0.166, P = 0.02). Thus, dietary and supplement interventions are required to prevent and control anaemia in this setting. Further research is needed.     

Synthesis of geranyl propionate in a solvent-free medium using Rhizomucor miehei lipase covalently immobilized on chitosan–graphene oxide beads

The chemical route of producing geranyl propionate involves the use of toxic chemicals, liberation of unwanted by-products as well as problematic separation process. In view of such problems, the use of Rhizomucor miehei lipase (RML) covalently bound onto activated chitosan–graphene oxide (RML-CS/GO) support is suggested. Following analyses using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetry, properties of the RML-CS/GO were characterized. A response surface methodological approach using a 3-level-four-factor (incubation time, temperature, substrate molar ratio, and stirring rate) Box–Behnken design was used to optimize the experimental conditions to maximize the yield of geranyl propionate. Results revealed that 76?±?0.02% of recovered protein had yielded 7.2?±?0.04?mg?g^?1 and 211?±?0.3%?U?g^?1 of the maximum protein loading and esterification activity, respectively. The actual yield of geranyl propionate (49.46%) closely agreed with the predicted value (49.97%) under optimum reaction conditions (temperature: 37.67°C, incubation time: 10.20?hr, molar ratio (propionic acid:geraniol): 1:3.28, and stirring rate: 100.70?rpm) and hence, verifying the suitability of this approach. Since the method is performed under mild conditions, the RML-CS/GO biocatalyst may prove to be an environmentally benign alternative for producing satisfactory yield of geranyl propionate.     

In silico and empirical approaches toward understanding the structural adaptation of the alkaline-stable lipase KV1 from Acinetobacter haemolyticus

Interests in Acinetobacter haemolyticus lipases are showing an increasing trend concomitant with growth of the enzyme industry and the widening search for novel enzymes and applications. Here, we present a structural model that reveals the key catalytic residues of lipase KV1 from A. haemolyticus. Homology modeling of the lipase structure was based on the structure of a carboxylesterase from the archaeon Archaeoglobus fulgidus as the template, which has a sequence that is 58% identical to that of lipase KV1. The lipase KV1 model is comprised of a single compact domain consisting of seven parallel and one anti-parallel β-strand surrounded by nine α-helices. Three structurally conserved active-site residues, Ser165, Asp259, and His289, and a tunnel through which substrates access the binding site were identified. Docking of the substrates tributyrin and palmitic acid into the pH 8 modeled lipase KV1 active sites revealed an aromatic platform responsible for the substrate recognition and preference toward tributyrin. The resulting binding modes from the docking simulation correlated well with the experimentally determined hydrolysis pattern, for which pH 8 and tributyrin being the optimum pH and preferred substrate. The results reported herein provide useful insights into future structure-based tailoring of lipase KV1 to modulate its catalytic activity.     

Increased incidence of Ia antigen-bearing T lymphocytes in the spontaneously diabetic BB rat

The frequency of Ia-positive T lymphocytes in spontaneously diabetic BB rats was assessed by using monoclonal antibodies and a fluorescence-activated cell sorter. These cells peaked in frequency during the early stages of hyperglycemia, with a gradual decline toward normal as the disease progressed. Significantly increased numbers of Ia-positive T cells were detected in both helper (W3/25+) and cytotoxic-suppressor (OX8+) subsets. The elevated levels of Ia-positive T lymphocytes in these rats may be relevant to the immune destruction of their beta cells.