Ramjai Wichainun

Sensitivity and specificity of ANA and anti-dsDNA in the diagnosis of systemic lupus erythematosus: a comparison using control sera obtained from healthy individuals and patients with multiple medical problems.

BACKGROUND Antinuclear antibodies (ANA) and anti-double stranded DNA (anti-dsDNA) are often tested as a screening tool in patients with suspected systemic lupus erythematosus or connective tissue diseases. ANA can be seen in healthy controls (HC) and patients with multiple medical problems (MMP). OBJECTIVE To determine the sensitivity and specificity of ANA and anti-dsDNA in SLE patients, using sera from HC and MMP patients. METHODS Serum samples from HC, MMP and SLE patients, 100 in each group, were analyzed for the presence of ANA and anti-dsDNA, by indirect immunofluorescent assay, using a HEp-2 cell and Crithidia luciliae as substrates, respectively. RESULTS The prevalence of ANA at a titer of ≥1:80 and ≥ 1:160 was 8% and 4%, respectively, in HC; and it was 12% and 6% respectively, in MMP patients. The prevalence of anti-dsDNA was 0% in HC and 3% in MMP patients. When using HC sera for the diagnosis of SLE, the sensitivity of ANA at a titer of ≥ 1:80 and ≥ 1:160 was 98% and 90%, respectively, with specificity of 92% and 96%, respectively. The specificity decreased to 88% and 94%, respectively, when using sera from MMP patients. The specificity of anti-dsDNA was 100% and 97%, when using sera from HC and MMP patients, respectively. CONCLUSION ANA and anti-dsDNA gave high sensitivity and high specificity in patients with SLE, even when using MMP patients sera as controls. Physicians should take care in interpreting ANA and anti-dsDNA results in MMP patients who do not have signs or symptoms of SLE or connective tissue diseases.

Effect of minidose aspirin on renal function and renal uric acid handling in healthy young adults

Minidose aspirin (60–325 mg/day) has been widely used in the prevention and treatment of cardiovascular and cerebrovascular diseases. However, studies on the effects of minidose aspirin on renal handling of uric acid and renal function are limited. We studied the effect of aspirin at 60 mg/day (n = 18) and 300 mg/day (n = 14) on uric acid handling and renal function in healthy subjects. The subjects were evaluated weekly during 2 weeks of aspirin therapy, and again 1 week after aspirin was discontinued. Aspirin at both dosages decreased the fractional excretion of uric acid. However, aspirin at 300 mg/day, but not 60 mg/day, significantly decreased uric acid clearance and creatinine clearance by the end of the second week of aspirin therapy. Despite these changes, serum uric acid and serum creatinine remained constant. The uric acid clearance, but not the creatinine clearance, returned to baseline value 1 week after aspirin therapy was discontinued. As aspirin at 60 mg/day showed no suppressive effect on renal function, it may be better for long-term use.

Lack of CTGF*-945C/G Dimorphism in Thai Patients with Systemic Sclerosis.

An association between connective tissue growth factor (CTGF) gene dimorphism at –945 (CTGF*-945C/G) and systemic sclerosis (SSc) has been reported with inconclusive results. We performed this study to determine whether such an association exists among Thai patients with SSc. DNA samples were taken from 50 Thai SSc patients (diffuse SSc in 39 and limited SSc in 11) and 99 healthy controls for determination of CTGF*-945C/G dimorphism by polymerase chain reaction (PCR) using specific oligonucleotide primers. The associations between the genotype frequencies, clinical manifestations and auto-antibodies were determined as well. When compared with the controls, SSc patients had no significantly higher frequencies of the GG genotype (44.0% vs 39.4%, p = 0.60), G allele (63.0% vs 65.2%, p = 0.80) or G phenotype (82.0% vs 90.9%, p = 1.0). There was no association between the presence of the GG genotype and clinical manifestations (pulmonary fibrosis, sclerodactyly, digital pitting scars, telangiectasia and pulmonary arterial hypertension), or the presence of auto-antibodies (anti-Scl-70, anti-SSA/Ro, and anti-RNP). In conclusion, we found no association between CTGF*-945C/G dimorphism and Thai SSc patients.

The genetic contribution of HLA‐DRB5*01:01 to systemic lupus erythematosus in Thailand

Human leucocyte antigen (HLA) study in patients with systemic lupus erythematosus (SLE) has been investigated in various countries, but the results are still inconclusive. This study was performed to investigate the association between HLA‐DR and SLE in patients in northern Thailand. HLA‐DR subtyping was performed in 70 patients with SLE and 99 normal healthy controls living in northern Thailand using the INNO‐LiPA HLA‐DR Decoder kit (Innogenetics) and MICRO SSP HLA DNA Typing kit (One Lambda) for reconfirmation. The allele frequency (AF) of DRB5*01:01 in SLE was significantly higher than in the controls [25.7% vs. 14.6%, P = 0.012, Pc = 0.048, OR = 2.02 (95%CI = 1.17–3.48)]. The AF of DRB1*15:01 and DRB1*16:02 showed a nonsignificant tendency to be higher in SLE (10.7% vs. 8.1%, and 17.9% vs. 11.1%). Interestingly, the DRB5*01:01 allele linked to DRB1*16:02 in 47.2% of SLE and 37.9% of controls, and the prevalence of the DRB1*16:02‐DRB5*01:01 haplotype was higher in the patients with SLE [12.1% vs. 5.6%, P = 0.044, OR = 2.35 (95%CI = 1.06–5.19)]. The DRB1*16:02 linked to DRB5*02:02 and *02:03 in 18.2% and 31.8% of controls, respectively, and linked to DRB5*02:03 in 32.0% of SLE patients. The frequency of DRB1*03:01 and *15:02 alleles was not increased in Thai SLE. There was no significant association between DRB5*01:01 and any auto‐antibodies or clinical manifestations of SLE. DRB5*01:01 is associated with Thai SLE, and the association is stronger than that of DRB1*15:01. The genetic contribution of DRB5*01:01 is due partially to the linkage disequilibrium between DRB1*16:02 and DRB5*01:01 in the northern Thai population.

Streptococcus agalactiae: An emerging cause of septic arthritis

ObjectiveInvasive Streptococcus agalactiae infection in nonpregnant women has been reported increasingly worldwide. This study reports the clinical features and outcome of S. agalactiae septic arthritis in Thai patients. MethodsThe medical records of cases with septic arthritis seen between July 1990 and December 2010 were reviewed. Only those with S. agalactiae were included in this study. ResultsFrom 244 cases of septic arthritis, 38 (15.57%, 13 men and 25 women) were caused by S. agalactiae, with 34 of them (89.48%) occurring between 2008 and 2010. Their mean age was 52.89 (SD, 18.95) years. Twenty-four of the 38 patients (63.16%) had 1 or more underlying disease that might predispose to joint infection. Fever and joint pain were the most common symptoms presented. Eleven cases (28.95%) presented monoarthritis, 15 (39.47%) oligoarthritis, and 12 (31.58%) polyarthritis, with a mean joint involvement of 3.34 (SD, 2.35) joints (range, 1–8). Cellulitis was seen in 27 cases (71.05%). Blood cultures were positive in 31 patients (81.58%). Thirty-five of the 38 synovial fluid specimens obtained were enough for cultures and stain smears, with 24 (68.57%) growing S. agalactiae and 19 (54.29%) showing gram-positive cocci. All isolates were sensitive to penicillin. Ten patients (26.31%) received arthroscopic drainage. The articular outcome was good in 11 patients, fair in 24, and poor in 3. There were no deaths. ConclusionsStreptococcus agalactiae is an emerging cause of septic arthritis in Thai patients. Physicians should be especially aware of this condition in patients presenting with acute oligopolyarthritis and prominent cellulitis.