Detection of antibodies to Trypanosoma cruzi among blood donors in the southwestern and western United States. II. Evaluation of a supplemental enzyme immunoassay and radioimmunoprecipitation assay for confirmation of seroreactivity

BACKGROUND: Chagas' disease, caused by the protozoan parasite Trypanosoma cruzi, is endemic to Latin America and may be transmitted in the United States via blood donated by infected immigrants. Blood- borne pathogens such as T. cruzi require supplemental testing for confirmation of seroreactivity. STUDY DESIGN AND METHODS: A study was undertaken to determine an optimal scheme for confirmation of seroreactivity in repeatedly reactive samples identified by the Chagas antibody enzyme immunoassay (EIA). The procedure for initial confirmation involves three purified antigens coated onto three separate polystyrene beads and uses an EIA format. If the sample is reactive with two of three or three of three antigens, it is confirmed as seroreactive. If none or one of three beads is reactive, the sample is indeterminate and subjected to a radioimmunoprecipitation assay (RIPA). The RIPA must demonstrate characteristic bands at 32, 34, and 90 kDa. RESULTS: When tested with sera from persons with potentially cross-reactive diseases (n = 39) or against a presumed negative population from southeast Wisconsin (n = 289), the confirmatory EIA had a specificity of 100 percent. Sensitivity was 100 percent (28/28) with xenodiagnosis-positive sera and 97.6 percent (80/82) with chagasic sera from Latin America. The RIPA showed a specificity of 100 percent in EIA- nonreactive samples (n = 100) and a sensitivity of 100 percent with both xenodiagnosis-positive (28/28) and chagasic (82/82) sera. CONCLUSION: The confirmatory EIA and the RIPA together provide a highly specific and sensitive means of confirming seroreactivity for antibodies to T. cruzi.     

Felodipine compared to nifedipine as "third-line drug" in resistant hypertension

Felodipine is a new dihydropyridine calcium antagonist, and in hypertension it is a much more effective "third-line" drug than hydralazine. Nifedipine, on the other hand, is the established dihydropyridine calcium antagonist that has been increasingly used to treat hypertension. Information is now needed on the relative merits and demerits of these two drugs. This study appraised, therefore, the therapeutic utility of twelve months' treatment with nifedipine 20-60 mg twice daily in 55 patients with previous drug-resistant hypertension who had been successfully treated for the previous year with felodipine 5-20 mg twice daily, each calcium antagonist being used in combination with atenolol 100 mg daily with or without chlorthalidone 25 mg daily. Initially, nifedipine maintained comparable blood pressure control to that which had been achieved by felodipine, although in the longer term (over eight months) nifedipine proved less effective than felodipine had (p less than 0.02) and more patients became uncontrolled (supine diastolic blood pressure, Phase V, greater than or equal to 90 mmHg) on the maximum tolerated dose of the calcium antagonist (chi 2 = 4.13, p less than 0.05 greater than 0.025). The former degree of blood pressure control was, however, reestablished by increasing the dose of nifedipine or reintroducing the diuretic as necessary, and this control was maintained over the next four months. Minor side effects were less common on nifedipine than they had been during the preceding felodipine treatment phase. Felodipine thus has more pronounced and sustained antihypertensive effects than nifedipine, though its side effect burden may appear to be greater.(ABSTRACT TRUNCATED AT 250 WORDS)     

Modest abuse-related subjective effects of zolpidem in drug-naive volunteers

Recent case reports suggest that the short-acting benzodiazepine-like hypnotic, zolpidem, may have abuse potential among individuals who have no personal history of abusing drugs or alcohol, particularly at doses higher than those recommended for treating insomnia. This study recruited drug-naive volunteers to assess the subjective effects of multiple doses of zolpidem (0, 5, 10, or 20 mg) administered in a within-subject double-blind design. Participants (n=11) answered computerized questionnaires (Addiction Research Center Inventory, visual analog scales, and a hypothetical Drug versus Money Choice) to address the hypothesis that a supratherapeutic dose (20 mg) would increase ratings of abuse-related subjective effects, while lower therapeutic doses (5 and 10 mg) would not. Although participants rated some effects as negative at 10 and 20 mg, the highest dose engendered predominantly positive abuse-like effects such as 'High', 'Like', and 'Good Effects'. However, no dose of zolpidem was chosen over money ($0.35-$10) when participants made hypothetical choices between them. Results suggest that although individuals without a drug abuse history are not inclined to choose zolpidem when presented with an alternative reinforcer such as money, it may possess moderate abuse potential that limits its clinical utility.     

Serum Serotonin Abnormality in Depression

Background

Serotonin plays an important role in treatment of depression. We evaluated the clinical correlates of plasma serotonin levels in depressed patients before and after treatment.

Methods

Study sample comprised of 40 patients diagnosed on ICD-10 diagnostic criteria, and an equal number of healthy matched controls. Subjects were evaluated on Beck''s Depression Inventory (BDI) and Suicide Ideation Scale (SIS), before and after the treatment. Blood samples were collected from all the cases and controls before starting the antidepressant medication with selective serotonin reuptake inhibitors (SSRI''s). Serum serotonin levels were measured before and after treatment.

Result

Significant differences in scores before and after the intervention on BDI, SIS and serotonin levels of cases and controls (p<.000) were noted. Correlation between the serum serotonin levels before and after the treatment, and between the rating scales did not reveal significant association (p > 0.05). Patients with suicidal intentions had lower levels of serotonin. The scores changed after intervention.

Conclusion

Treatment with SSRI''s had shown significant changes in clinical conditions. However these changes did not relate significantly with serum serotonin levels.Key Words: Serotonin, Depression, Selective serotonin reuptake inhibitors     

Validation of MCADD newborn screening

Medium‐chain acyl‐CoA dehydrogenase deficiency (MCADD) represents a potentially fatal fatty acid β‐oxidation disorder. Newborn screening (NBS) by tandem mass spectrometry (MS/MS) has been implemented worldwide, but is associated with unresolved questions regarding population heterogeneity, burden on healthy carriers, cut‐off policies, false‐positive and negative rates. In a retrospective case‐control study, 333 NBS samples showing borderline acylcarnitine patterns but not reaching recall criteria were genotyped for the two most common mutations (c.985A>G/c.199C>T) and compared with genotypes and acylcarnitines of 333 controls, 68 false‐positives, and 34 patients. c.985A>G was more frequently identified in the study group and false‐positives compared to controls (1:4.3/1:2.3 vs. 1:42), whereas c.199C>T was found more frequently only within the false‐positives (1:23). Biochemical criteria were devised to differentiate homozygous (c.985A>G), compound heterozygous (c.985A>G/c.199C>T), and heterozygous individuals. Four false‐negatives were identified because our initial algorithm required an elevation of octanoylcarnitine (C₈) and three secondary markers in the initial and follow‐up sample. The new approach allowed a reduction of false‐positives (by defining high cut‐offs: 1.4 μmol/l for C₈; 7 for C₈/C₁₂) and false‐negatives (by sequencing the ACADM gene of few suspicious samples). Our validation strategy is able to differentiate healthy carriers from patients doubling the positive predictive value (42→88%) and to target NBS to MCADD‐subsets with potentially higher risk of adverse outcome. It remains controversial, if NBS programs should aim at identifying all subsets of all diseases included. Because the natural course of milder variants cannot be assessed by observational studies, our strategy could serve as a general model for evaluation of MS/MS‐based NBS.     

Inhibition of mitochondrial translation as a therapeutic strategy for human acute myeloid leukemia

To identify FDA-approved agents targeting leukemic cells, we performed a chemical screen on two human leukemic cell lines and identified the antimicrobial tigecycline. A genome-wide screen in yeast identified mitochondrial translation inhibition as the mechanism of tigecycline-mediated lethality. Tigecycline selectively killed leukemia stem and progenitor cells compared to their normal counterparts and also showed antileukemic activity in mouse models of human leukemia. ShRNA-mediated knockdown of EF-Tu mitochondrial translation factor in leukemic cells reproduced the antileukemia activity of tigecycline. These effects were derivative of mitochondrial biogenesis that, together with an increased basal oxygen consumption, proved to be enhanced in AML versus normal hematopoietic cells and were also important for their difference in tigecycline sensitivity.