The Hong Kong Society of Rheumatology consensus recommendations for the management of gout

Clinical Rheumatology - Gout is one of the most common noncommunicable diseases in Hong Kong. Although effective treatment options are readily available, the management of gout in Hong Kong remains...     

Application of fragment-based lead generation to the discovery of novel, cyclic amidine beta-secretase inhibitors with nanomolar potency, cellular activity, and high ligand efficiency

Fragment-based lead generation has led to the discovery of a novel series of cyclic amidine-based inhibitors of beta-secretase (BACE-1). Initial fragment hits with an isocytosine core having millimolar potency were identified via NMR affinity screening. Structure-guided evolution of these fragments using X-ray crystallography together with potency determination using surface plasmon resonance and functional enzyme inhibition assays afforded micromolar inhibitors. Similarity searching around the isocytosine core led to the identification of a related series of inhibitors, the dihydroisocytosines. By leveraging the knowledge of the ligand-BACE-1 recognition features generated from the isocytosines, the dihydroisocytosines were efficiently optimized to submicromolar potency. Compound 29, with an IC50 of 80 nM, a ligand efficiency of 0.37, and cellular activity of 470 nM, emerged as the lead structure for future optimization.     

Application of fragment screening by X-ray crystallography to beta-secretase

This paper describes an application of fragment screening to the aspartyl protease enzyme, beta-secretase (BACE-1), using high throughput X-ray crystallography. Three distinct chemotypes were identified by X-ray crystallography as binding to the catalytic aspartates either via an aminoheterocycle (such as 2-aminoquinoline), a piperidine, or an aliphatic hydroxyl group. The fragment hits were weak inhibitors of BACE-1 in the millimolar range but were of interest because most of them displayed relatively good ligand efficiencies. The aminoheterocycles exhibited a novel recognition motif that has not been seen before with aspartic proteases. Virtual screening around this motif identified an aminopyridine with increased potency and attractive growth points for further elaboration using structure-based drug design. The companion paper illustrates how sub-micromolar inhibitors were developed starting from this fragment.     

Normal growth of prepubertal nephrotic children during long-term treatment with repeated courses of prednisone

The growth of 21 prepubertal children with steroid-dependent frequently relapsing nephrotic syndrome was studied before and during treatment with repeated courses of oral prednisone for 4 y. The height and height velocity standard deviation scores (HSDS and HVSDS) of the nephrotic children were -0.11 and -0.06, respectively, at the onset of the disease and -0.12 and +0:05, +0:14 and +1:02, +0:21 and +0:78 and +0:17 and +0:66, respectively, thereafter yearly during the treatment. The mean yearly cumulative dose of prednisone was 6300, 3459, 2677 and 2081 mg/body area (m) at the first, second, third and fourth year, respectively. The nephrotic children grew normally for their age before onset of the disease and growth remained normal despite prednisone treatment.     

Characterization of the p67phox gene: genomic organization and restriction fragment length polymorphism analysis for prenatal diagnosis in chronic granulomatous disease

The genetic defect in the p67phox-deficient form of chronic granulomatous disease (CGD) follows an autosomal recessive pattern of inheritance. When genomic DNA from normal individuals is digested with HindIII and probed with p67phox cDNA an allelic restriction fragment length polymorphism (RFLP) of 4.0 kb or 2.3 kb is detected. We cloned and characterized the p67phox gene using the cDNA and sequenced the exon/intron boundaries, mapping 16 exons on the 40-kb gene. The polymorphic region was then sequenced to identify the inheritance pattern of amniocentesis-derived fetal cells by genomic amplification. The proband, a 9-year-old female patient with p67phox-deficient CGD, and her phenotypically normal mother are homozygous for the RFLP marker, whereas the father and two brothers are heterozygous. The fetus was shown to be heterozygous as well, showing it had inherited at least one normal p67phox gene from the father and that it was predicted to have a normal phenotype. Cord blood samples at birth showed normal oxidative function. Amplification allows rapid detection of the inheritance pattern for fetal diagnosis in informative families. We report the genomic structure of p67phox and an amplification-based method for detection of the marker on chromosome 1q25, used here for prenatal diagnosis of CGD.     

Three-year randomized controlled trial of dipyridamole and low-dose warfarin in patients with IgA nephropathy and renal impairment

Summary: Activation of platelets and the coagulation pathway are factors which may contribute to the progression of renal disease in IgA nephropathy (IgAN). Of 21 patients with IgAN and serum creatinines between 1.6 and 3.0 mg/dL, 10 were assigned to treatment with dipyridamole and low-dose warfarin (keeping the thrombotest between 30 and 50%) and 11 to no treatment in a prospective randomized 3-year study. At entry into the trial, patients in the treatment group were younger (35 ± 6 years vs 42 ± 9 years) and had worse histological scores for tubular atrophy (1.7 ± 0.7 vs 1.1 ± 0.5) and arteriolar hyperplasia (1.4 ± 0.7 vs 0.7 ± 0.8) than those in the non-treatment group. There were no differences in serum creatinine values, creatinine clearances, urinary protein excretions, serum albumins or urinary erythrocyte counts. At the end of the trial, patients on treatment did not experience a significant increase in serum creatinine values (1.9 ± 0.3 mg/dL to 2.5 ± 1.2) or reduction in creatinine clearances (52 ± 20mL/min to 52 ± 27). Untreated patients, however, experienced a significant rise in serum creatinine values (2.1 ± 0.5 mg/dL to 3.3 ± 1.1, P < 0.01) and a fall in creatinine clearances (51 ± 26 mL/min to 31 ± 22, P = 0.06). There was no significant change in the proteinuria in either group (treatment group: 1.2 ± 1.2 g/day to 1.3 ± 1.1, non-treatment group: 1.9 ± 1.4 to 1.5 ± 1.1) and there was also no change in serum albumins and urinary erythrocyte counts. Four untreated and one treated patient developed end-stage renal failure during the course of the trial. This study suggests that treatment of patients with IgAN and renal impairment with dipyridamole and low-dose warfarin retards the deterioration of renal function, as measured by the serum creatinine and creatinine clearance.     

参三七皂甙Rg1对实验性血栓形成的影响及其机制探讨

用大鼠动静脉血栓形成模型,研究参三七皂甙Rg₁抗血栓作用。结果表明,参三七皂甙Rg₁可明显降低实验性血栓形成,对大鼠血浆纤溶系统亦有明显作用,可升高血浆中组织纤溶酶原激活物(t-PA)活性和活性型t-PA百分比,降低组织纤溶酶原激活物抑制剂(PAI)活性。同时利用培养大鼠血管内皮细胞实验,发现Rg₁可以剂量依赖性提高血管内皮细胞一氧化氮(NO)释放。提示Rg₁抗血栓作用与增强纤溶系统活性,促进血管内皮NO释放有关。