To improve the diagnosis efficiency of human strongyloidiasis by using formalin-ether concentration technique (FECT), the effects of various factors on the recovery rates of Strongyloides stercoralis larvae were comparatively evaluated. Fresh stool and a short time exposure of larvae to formalin yielded significantly higher numbers of larvae than preserved stool and 10-min exposure. Likewise, straining through wire mesh yielded a significantly higher number of larvae recovered than straining through gauze did. In addition, centrifugation for 5 min for separation of larvae from debris yielded a significantly greater number of larvae recovered than centrifugation for 2 min did. The efficacies of the five versions of FECT with different factors-FECT 1, FECT 2, FECT 3, FECT 4, and FECT 5-were then compared. It was found that FECT 5 was 1.8, 2.0, 1.9, and 1.4 times more effective than FECT 1, FECT 2, FECT 3, and FECT 4, respectively. FECT 5 is a modified FECT method, whose modifications included using fresh stool without a preservative substance; a short-time rather than 10-min formalin exposure; and the use of wire mesh instead of gauze. Strongyloidiasis caused by Strongyloides stercoralis is a harmful infectious disease for immunosuppressed patients (5).The most accurate method for diagnosis of strongyloidiasis, which is widely used in areas where this disease is endemic, is to detect S. stercoralis larvae in stool, whereas detection by indirect methods, especially immunological techniques, are not as effective (11). Agar plate culture (APC) has consistently been found to be 1.6 to 6.0 times more effective than formalin-ether concentration technique (FECT) (1, 8). However, APC has many disadvantages: it is time-consuming and costly, has a tendency of risk of larval infection (7, 8), and demonstrates a particular inability to detect 10% (6) to 20% (12) of positive samples detected by FECT. Thus, if the efficacy of FECT can be improved, a more precise diagnosis of strongyloidiasis will be obtained. Many laboratory personnel believe that variations in the skill and experience of examiners caused the effectiveness of APC shown to be 1.6 to 6.0 times greater than FECT (1). However, there could possibly be some concealed factors causing the lower sensitivity of FECT.A pilot study was thus conducted using a large number of S. stercoralis larvae in diluted stool samples from patients with strongylodiasis (kept for 2 months in 10% formalin) for the capability of larval counting. FECT was performed, after which four layers were formed: ether, plug of debris, formalin and sediment. The results showed that 62.5% of larvae were in the debris plug, 32.5% floated in the formalin layer, and only 5% settled in the sediment. The diluted stool samples were also comparatively filtered either through two layers of wet gauze or two layers of wire mesh (0.7-by 0.7-mm and 1.2-by 1.2-mm pore sizes). The results revealed that a significantly lower number of larvae were recovered in the experiment using gauze than with the two wire meshes. T...
Although there is evidence for an important role of UGT2B10 in the N-glucuronidation of drugs and other xenobiotics, the inhibitor selectivity of this enzyme is poorly understood. This study sought primarily to characterize the inhibition selectivity of UGT2B10 by UDP-glucuronosyltransferase (UGT) enzyme-selective inhibitors used for reaction phenotyping, and 34 antidepressant and antipsychotic drugs that contain an amine functional group. Initial studies demonstrated that cotinine is a highly selective substrate of human liver microsomal UGT2B10. The kinetics of cotinine N-glucuronidation by recombinant UGT and human liver microsomes (6 bovine serum albumin) were consistent with the involvement of a single enzyme. Of the UGT enzyme-selective inhibitors employed for reaction phenotyping, only the UGT2B4/7 inhibitor fluconazole reduced recombinant UGT2B10 activity to an appreciable extent. The majority of antidepressant and antipsychotic drugs screened for effects on UGT2B10 inhibited enzyme activity with IC 50 values <100 mM. The most potent inhibition was observed with the tricyclic antidepressants amitriptyline and doxepin and the tetracyclic antidepressant mianserin, and the structurally related compounds desloratadine and loratadine. Molecular modeling using a ligand-based approach indicated that hydrophobic and charge interactions are involved in inhibitor binding, whereas spatial features influence the potency of UGT2B10 inhibition. Respective mean K i,u (6 S.D.) values for amitriptyline, doxepin, and mianserin inhibition of human liver microsomal UGT2B10 were 0.61 6 0.05, 0.95 6 0.18, and 0.43 6 0.01 mM. In vitro-in vivo extrapolation indicates that these drugs may perpetrate inhibitory drug-drug interactions when coadministered with compounds that are cleared predominantly by UGT2B10.
We succeeded in stimulation of excretion of Strongyloides stercoralis larvae in stool by oral administration of a single dose of 400 mg albendazole to strongyloidiasis patients. This result overcame the false-negative results of stool examination due to low larval numbers. Stool samples were collected from 152 asymptomatic strongyloidiasis patients in the morning, prior to eating. After breakfast, they were given a dose of 400 mg albendazole, and stool samples were collected the following morning. Agar plate culture (APC), modified formalin-ether concentration technique (MFECT), and direct-smear (DS) methods were used to examine stool specimens within 3 h after defecation. The results before and after albendazole was taken were compared. All APCs that were positive became negative after albendazole administration, while MFECT showed a 1.4-to 18.0-fold increase in larval numbers in 97.4% (148/152) of the samples. The DSs were positive in 3 out of 3 smears at a larval number of >45 larvae per g (lpg) of stool, and in 1or 2 out of 3 smears at a larval number between 35 and 44 lpg. At a larval number of <35 lpg, the DS became negative. Interestingly 90.5% (19/21) of the samples that were negative by all methods before albendazole administration became positive by MFECT after the treatment. Thus, MFECT can be effectively used for diagnosis of strongyloidiasis with prior administration of albendazole to the subject.
Dispersion or dilution of stool by water from heavy rainfall may affect Strongyloides stercoralis free-living development producing infective filariform larvae (FL). This study examined effect of water dilution of stool on survival of S. stercoralis free-living development. One g of stool was prepared in water so that its soluble component was diluted sequentially from 1:2 to 1:480. Three dishes were used to compare FL production in three culture conditions: stool suspension, stool sediment deposited in soil, and isolated rhabditiform larvae (RhL) deposited in soil. The fourth dish was for developmental observation of RhL into free-living stages. Numerous FL were generated from undiluted or 1:2 diluted stool and stool sediment placed on soil. However, starting from dilution 1:5, FL production continuously decreased in both stool suspensions and stool sediments placed on soil. RhL isolated from stool dilutions placed on soil gave rise to few FL. Worm mating were seen at 24-30 hours in dilutions 1:20-1:120 only. Highest numbers of FL from indirect free-living cycle were 1/3 of those from control. FL production decreased as stool dilution increased, and reached zero production at 1:160 dilution. Rainfall may disperse or dilute stool so that nutritional supplement for S. stercoralis free-living development is insufficient.
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