Chagas' disease diagnosis: evaluation of several tests in blood bank screening

Blood transfusion is one of the principal routes of transmission of Chagas' disease, a major endemic disease in Latin America. Methods for blood screening are not accurate and may yield false results that lead to high social and economic costs. This study compares two methods of diagnosing Chagas' disease (indirect immunofluorescence and hemagglutination) and several enzyme-linked immunosorbent assays (ELISAs) with regard to specificity and sensitivity, by using human sera with known serologic and parasitologic characteristics, as well as samples with discrepant results on conventional serologic tests. An ELISA using recombinant antigens showed no cross-reactivity with sera that were positive for other diseases. All evaluated ELISAs performed well, and their use may lead to a reduction of more than 50 percent in the number of discordant sera. Further improvements are needed in view of the complexity of the serologic diagnosis of Chagas' disease.     

Virtual colonoscopy with magnetic resonance imaging: In vitro evaluation of a new concept

BACKGROUND & AIMS: Screening for colonic polyps is desirable. A new concept based on cross-sectional and endoscopic analysis of a magnetic resonance (MR) data set is presented. METHODS: Ex vivo autopsy colonic specimens, containing artificially placed polyps, were obtained and filled with a gadolinium-containing solution. Forty-four thin-section MR images were obtained in a 1.5-T MR scanner in 28 seconds. A three- dimensional endoscopic fly-through of these images was rendered. Fly- throughs and two-dimensional cross-sectional images were analyzed by two observers for the presence of polyps. RESULTS: The average sensitivity and specificity for the detection of polyps based on three- dimensional endoscopic MR colon imaging were 87% and 96%, respectively. Analysis of cross-sectional images showed an overall sensitivity and specificity of merely 57% and 84%, respectively. The difference in the interpretation of three-dimensional MR colonoscopy and two-dimensional cross-sections was statistically significant (P < 0.001). With three- dimensional MR colonoscopy, overall sensitivity for detection of polyps measuring < or =5 mm in length and diameter was 70%; for larger polyps, it increased to 95% (P < 0.01). CONCLUSIONS: The feasibility of an MR- based endoluminal assessment of the colon is shown. Minimal invasiveness, lack of radiation exposure, and high in vitro diagnostic accuracy warrant further investigation of this novel concept. (Gastroenterology 1997 Jun;112(6):1863-70)     

Visualization of a peripheral stalk in V-type ATPase: Evidence for the stator structure essential to rotational catalysis

F- and V-type ATPases are central enzymes in energy metabolism that couple synthesis or hydrolysis of ATP to the translocation of H⁺ or Na⁺ across biological membranes. They consist of a soluble headpiece that contains the catalytic sites and an integral membrane-bound part that conducts the ion flow. Energy coupling is thought to occur through the physical rotation of a stalk that connects the two parts of the enzyme complex. This mechanism implies that a stator-like structure prevents the rotation of the headpiece relative to the membrane-bound part. Such a structure has not been observed to date. Here, we report the projected structure of the V-type Na⁺-ATPase of Clostridium fervidus as determined by electron microscopy. Besides the central stalk, a second stalk of 130 Å in length is observed that connects the headpiece and membrane-bound part in the periphery of the complex. This additional stalk is likely to be the stator.     

Phase II trial of 2-chlorodeoxyadenosine for the treatment of cutaneous T-cell lymphoma [see comments]

We investigated the efficacy of 2-chlorodeoxyadenosine (2-CdA) therapy in patients with mycosis fungoides (MF) and the Sezary syndrome (SS). Between February 1991 and November 1993, 21 patients with relapsed or refractory MF/SS were treated with 2-CdA. 2-CdA was administered by continuous intravenous infusion at a dose of 0.1 mg/kg/d for 7 days initially (13 patients), but was subsequently reduced to 5 days (nine patients) due to hematologic toxicity. All patients had failed to respond to at least one prior treatment for MF/SS (median number of total prior therapies, five; median number of systemic prior therapies, three) and had an Eastern Cooperative Oncology Group performance status of two or better. Cycles were administered at 28-day intervals. Assessable patients received at least 5 days of 2-CdA. Fourteen patients received more than one cycle of 2-CdA. An overall response rate of 28% was achieved. Three patients (14%) had a complete response with a median duration of 4.5 months (range, 2.5 to 16). Three (14%) had a partial response with a median duration of 2 months (range, 2 to 4). Fifteen patients (72%) had no response. The most significant toxicities encountered were bone marrow suppression (62% of patients) and infectious complications (62% of patients). Thirty-eight percent of patients experienced no toxicity from 2-CdA. 2-CdA has activity as a single agent in patients with previously treated relapsed MF/SS. Studies in less heavily pretreated individuals with 2-CdA alone or in combination will be undertaken.     

Systematic mechanism-orientated approach to chronic pancreatitis pain

Pain in chronic pancreatitis(CP) shows similarities with other visceral pain syndromes(i.e.,inflammatory bowel disease and esophagitis),which should thus be managed in a similar fashion.Typical causes of CP pain include increased intrapancreatic pressure,pancreatic inflammation and pancreatic/extrapancreatic complications.Unfortunately,CP pain continues to be a major clinical challenge.It is recognized that ongoing pain may induce altered central pain processing,e.g.,central sensitization or pro-nociceptive pain modulation.When this is present conventional pain treatment targeting the nociceptive focus,e.g.,opioid analgesia or surgical/endoscopic intervention,often fails even if technically successful.If central nervous system pain processing is altered,specific treatment targeting these changes should be instituted(e.g.,gabapentinoids,ketamine or tricyclic antidepressants).Suitable tools are now available to make altered central processing visible,including quantitative sensory testing,electroencephalograpy and(functional) magnetic resonance imaging.These techniques are potentially clinically useful diagnostic tools to analyze central pain processing and thus define optimum management approaches for pain in CP and other visceral pain syndromes.The present review proposes a systematic mechanism-orientated approach to pain management in CP based on a holistic view of the mechanisms involved.Future research should address the circumstances under which central nervous system pain processing changes in CP,and how this is influenced by ongoing nociceptive input and therapies.Thus we hope to predict which patients are at risk for developing chronic pain or not responding to therapy,leading to improved treatment of chronic pain in CP and other visceral pain disorders.     

Q-T prolongation and ventricular arrhythmias, with and without deafness, in the same family

A family with the cardio-auditory syndrome is presented to show for the first time that members can have a prolonged Q-T interval and syncope, both with and without mild congenital high-frequency deafness. The auditory and cardiac defects appear to be inherited separately and on the basis of an autosomal dominant mechanism in this family. In the propositus with Q-T interval prolongation and recurrent ventricular arrhythmias without deafness, intravenous administration of diphenylhydantoin shortened the Q-T interval. Intravenous administration of phenylephrine induced ventricular fibrillation. Cardiac pathologic examination in a sibling of the propositus who had syncope before a fatal automobile accident showed areas of fibrosis in the conduction system.     

Normal cellular counterparts of B cell chronic lymphocytic leukemia

In an attempt to compare B cell chronic lymphocytic leukemia (B-CLL) with its normal cellular counterpart, the cell surface phenotype of 100 cases of B-CLL was determined by using a panel of monoclonal antibodies (MoAbs) directed against B cell-restricted and -associated antigens. The majority of B-CLL cells expressed Ia, B4 (CD19), B1 (CD20), B2 (CD21), surface immunoglobulin (sIg), and T1 (CD5) but lacked C3b (CD35) receptors. In contrast, the overwhelming majority of small unstimulated B cells expressed Ia, B4, B1, B2, sIg, and C3b receptors but lacked detectable T1. Small numbers of weakly sIg+ cells could be identified in peripheral blood and tonsil that coexpressed the B1 and T1 antigens. Approximately 16% of fetal splenocytes coexpressed B1, T1, weak sIg, B2, and Ia but lacked C3b receptors and therefore closely resembled most B-CLL cells. With the phenotypic differences between the majority of small unstimulated B cells and B-CLL cells, we examined normal in vitro activated B cells and B-CLL cells for the expression of B cell-restricted and -associated activation antigens. Of 20 cases examined, virtually all expressed B5, and approximately 50% of the cases expressed interleukin-2 receptors (IL-2R) and Blast-1. Normal B cells were activated with either anti-Ig or 12-0-tetradecanoylphorbol- beta-acetate (TPA) and then were examined for coexpression of B1, T1, and the B cell activation antigens B5 and IL-2R. Only cells activated with TPA coexpressed B1 and T1 as well as B5 and IL-2R. B cells activated with either anti-Ig or TPA proliferated in the presence of IL- 2, whereas B-CLL cells did not, although they all expressed the identical 60-kilodalton proteins by immunoprecipitation. These studies are consistent with the notion that B-CLL resembles several minor subpopulations of normal B cells including a population of B cells that are activated in vitro directly through the protein kinase C pathway.     

Immunologic heterogeneity of diffuse large cell lymphoma

The cellular lineage of 57 diffuse large-cell lymphomas (DLCLs) was determined using a panel of monoclonal antibodies directed against lineage-restricted and -associated T, B, and monocyte antigens. The majority (82%) were of B cell lineage as determined by the expression of sig and/or B1, with the remaining 16% being of T cell lineage and 2%, of monocyte-myeloid lineage. By the expression of other B cell- restricted and -associated antigens, two major and two minor subgroups could be identified. These subgroups expressed the following phenotypes: (1) B1+B4+sIG+B2- (51%); (2) B1+B4+sIg+B2+ (29%); (3) B1+B4+sIg-B2+ (10%); and (4) B1+B4-sIg+B2- (10)%. The morphology of transformed lymphocytes, the weak to absent expression of the early B cell antigens B2 and sIgD, and the absence of the late B cell differentiation antigens PCA-1 and PC-1 suggested that these tumors were the neoplastic counterparts of normal B cells at the mid-stages of differentiation. Further support for the notion that B-DLCLs correspond to transformed B lymphocytes was concluded from the observation that B cells could be identified in normal spleen that expressed the cell surface phenotype and morphological appearance of the majority of B- DLCLs.     

Colony-forming cell proliferation: a rapid and sensitive assay system for murine granulocyte and macrophage colony-stimulating factors

A microculture assay for murine granulocyte-macrophage colony- stimulating factor (GM-CSF) has been developed using fetal liver GM colony-forming cells (CFC) isolated by fluorescence-activated cell sorting. These GM-CFC are free of mature hemopoietic cells, such as granulocytes and macrophages, which may interfere with direct assays for GM-CSF. The assay procedure allows the quantitation of GM-CSF within 48 hr by measuring the number of cells produced from 50 GM-CFC in microcultures (15 microliter). The assay is particularly simple to set up and score and yet, because of the reduced volumes, this assay is still capable of detecting 0.2 pg (i.e., 0.2 U) of GM-CSF within 48 hr, i.e., 100 times less GM-CSF than the conventional soft agar assay. By allowing the microcultures to develop for 7 days, the extra proliferation allows a further tenfold increase in the sensitivity of CSF detection. The time and cost of setting up hundreds of GM-CSF assays for fractions from chromatographic columns, e.g., reverse phase high performance liquid chromatography, is reduced by at least five- fold. Enough GM-CFC can be isolated and stored frozen in one afternoon to provide sufficient cells for the daily assay of 200 samples of GM- CSF for several months. Microassay results for several sources of GM- CSF at different stages of purification are compared to the results obtained from the soft agar assay.