T2 mapping with magnetization‐prepared 3D TSE based on a modified BIR‐4 T2 preparation

The purpose of this work was to investigate the performance of the modified BIR‐4 T₂ preparation for T₂ mapping and propose a method to remove T₂ quantification errors in the presence of large B₁ and B₀ offsets. The theoretical investigation of the magnetization evolution during the T₂ preparation in the presence of B₁ and B₀ offsets showed deviations from a mono‐exponential T₂ decay (two parameter fit). A three parameter fit was used to improve T₂ accuracy. Furthermore, a two parameter fit with an additional saturation preparation scan was proposed to improve T₂ accuracy and precision. These three fitting methods were compared based on simulations, phantom measurements and an in vivo healthy volunteer study of the neck musculature using a 3D TSE readout. The results based upon the pure two parameter fit overestimated T₂ in regions with high B₀ offsets (up to 40% in phantoms). The three parameter fit T₂ values were robust to B₀ offsets but with higher standard deviation (up to 40% in simulations). The two parameter fit with the saturation preparation yielded high robustness towards B₀ offsets with a noise performance comparable to that of the two parameter fit. In the volunteer study the T₂ values obtained by the pure two parameter fit showed a dependence on the field inhomogeneities, whereas the T₂ values from the proposed fitting approach were shown to be insensitive to B₀ offsets. The proposed method enabled accurate and precise T₂ mapping in the presence of large B₁ and B₀ offsets.     

Analysis of human immunodeficiency virus-infected tissues by amplification and in situ hybridization reveals latent and permissive infections at single-cell resolution.

Latent and productive viral infections are at the extremes of the spectrum of virus-cell interactions that are thought to play a major role in the ability of such important human pathogens as human immunodeficiency virus (HIV) to elude host defenses and cause disease. The recent development of PCR-based methods to amplify target sequences in individual cells in routinely fixed tissues affords opportunities to directly examine the subtle and covert virus-cell relationships at the latent end of the spectrum that are inaccessible to analysis by conventional in situ hybridization techniques. We have now used PCR in situ with in situ hybridization to document latent and permissive HIV infection in routinely fixed and paraffin-embedded tissue. In one of the first specimens we examined, a tumor biopsy from an HIV-infected individual, we found many of the lymphocytes and lymphocytes infiltrating the tumor had HIV DNA that was detectable only by PCR in situ. The fraction of positive cells varied regionally, but there were foci where most of the cells contained HIV DNA. Most of these lymphocytes and macrophages are latently infected, as we could detect HIV RNA in fewer than one in a thousand of these cells. We also detected HIV RNA, surprisingly, in 6% of the tumor cells, where the number of copies of viral RNA per cell was equivalent to productively infected cell lines. The alternative states of HIV-gene expression and high local concentration of latently infected lymphocytes and monocytes revealed by these studies conceptually supports models of lentiviral pathogenesis that attribute persistence to the reservoir of latently infected cells and disease to the consequences of viral-gene expression in this population. The magnitude of infection of lymphocytes documented in this report is also consistent with the emerging view that HIV infection per se could contribute substantially to depletion of immune cells in AIDS.     

Familial protein S deficiency with a variant protein S molecule in plasma and platelets

A protein S deficient family presenting a variant protein S molecule in plasma and platelets is described. The propositus, age 20, and two brothers suffered from venous thrombotic disease. The propositus, the only family member studied while taking oral anticoagulants, had a protein S antigen (ag) level of 17% and undetectable activity. As demonstrated by immunoblotting both the propositus and one clinically affected brother (42% ag, 7% activity) presented variant protein S molecules of 65,000 molecular weight (mol wt) while the other clinically affected brother (64% ag, 11% activity) had only protein S with normal electrophoretic mobility of 70,000 mol wt. The mother had normal protein S levels (93% ag, 100% activity) but had both normal and variant protein S molecules and based on her functional protein S data a normal anticoagulant activity of the variant molecule is suggested. One asymptomatic but protein S deficient sister (68% ag, 9% activity) as well as the asymptomatic protein S deficient father (59% ag, 10% activity) had only protein S molecules of 70,000 mol wt. The variant protein S bound to C4b-binding protein in plasma, and differed from normal protein S in carbohydrate content. Platelets of each family member contained the same immunoblotting pattern of normal and variant protein S forms as found in plasma, consistent with the hypothesis that protein S gene expression involves codominant expression of two alleles that is similar in cells that control the synthesis of both platelet and plasma forms of protein S.     

Granulocyte colony-stimulating factor administration to healthy volunteers: analysis of the immediate activating effects on circulating neutrophils

In four healthy volunteers, we analyzed in detail the immediate in vivo effects on circulating neutrophils of subcutaneous administration of 300 micrograms of granulocyte colony-stimulating factor (G-CSF). Neutrophil activation was assessed by measurement of degranulation. Mobilization of secretory vesicles was shown by a decrease in leukocyte alkaline phosphatase content of the circulating neutrophils. Furthermore, shortly postinjection, Fc gamma RIII was found to be upregulated from an intracellular pool that we identified by immunoelectron microscopy as secretory vesicles. Intravascular release of specific granules was shown by increased plasma levels of lactoferrin and by upregulation of the expression of CD66b and CD11b on circulating neutrophils. Moreover, measurement of fourfold elevated plasma levels of elastase, bound to its physiologic inhibitor alpha 1- antitrypsin, indicated mobilization of azurophil granules. However, no expression of CD63, a marker of azurophil granules, was observed on circulating neutrophils. G-CSF--induced mobilization of secretory vesicles and specific granules could be mimicked in whole blood cultures in vitro, in contrast to release of azurophil granules. Therefore, we postulate that the most activated neutrophils leave the circulation, as observed shortly postinjection, and undergo subsequent stimulation in the endothelial microenvironment, resulting in mobilization of azurophil granules. Our data demonstrate that G-CSF should be regarded as a potent immediate activator of neutrophils in vivo.     

Characterization of consecutive Streptococcus pyogenes isolates from patients with pharyngitis and bacteriological treatment failure: special reference to prtF1 and sic / drs

To analyze bacteriological treatment failure in streptococcal pharyngitis, 40 consecutive Streptococcus pyogenes isolates from 18 patients were characterized. For 17 patients, isolates were indistinguishable with respect to emm type, random amplified polymorphic DNA pattern, and presence of prtF1 encoding the fibronectin-binding protein F1. prtF1 was detected only in the 11 isolates (4 patients) with emm12 and in the single isolate with emm6. Further analysis by vir(mga) regulon typing, sequencing of sic encoding the streptococcal inhibitor of complement from 19 isolates with emm1 (9 patients), and sequencing of drs (distantly related sic) from 11 isolates with emm12 revealed distinct sic alleles with insertions and/or deletions in sic that corresponded to differences in restriction patterns of the vir(mga) regulon only for paired isolates of 2 patients. Among isolates with emm12, 2 novel drs alleles were found. Analysis of these data suggests that neither the presence of prtF1 nor the diversification of sic / drs is required for the persistence of S. pyogenes in pharyngitis.     

Induction of a hematological and cytogenetic remission in a patient with a myelodysplastic syndrome secondary to Fanconi's anemia employing the S-HAM regimen

 We report on a patient with Fanconi's anemia (FA) who developed a myelodysplastic syndrome (RAEB-T) with complex karyotypic abnormalities (trp 1q23 q 42, monosomy 20, trisomy 13) at the age of 28. The patient achieved a complete hematological and cytogenetic remission after treatment with sequential high-dose cytosine arabinoside/mitoxantrone followed by G-CSF (5 μg/kg). Bone marrow hypoplasia was prolonged with 38 days of granulocytopenia <500/μl and 62 days of platelet transfusion dependency. Nonhematological toxicity did not exceed that of patients without underlying FA. Remission duration was 7 months. This observation shows the feasibility of high-dose Ara C treatment in patients with FA and MDS. Although hematopoiesis remained clonal in remission, the suppression of the cytogenetically abnormal clones transiently reversed the antecedent long-lasting pancytopenia. Received: 16 September 1996 / Accepted: 27 January 1997     

In vivo validation of an experimental adaptive quantitative coronary angiography algorithm to circumvent overestimation of small luminal diameters

The reliability of quantitative coronary angiography (QCA) measurements is of fundamental importance for the study and practice of interventional cardiology. In vivo validation results have consistently reported a tendency for QCA systems to overestimate small luminal diameters. Such a systematic error may result in the underestimation of luminal gain during intracoronary procedures and in the underestimation of progression of coronary artery disease during longitudinal studies. We report the in vivo validation results of an experimental adaptive edge-detection algorithm that was developed to reduce overestimation of small luminal diameters by incorporating a dynamic function of variable kernel size of the derivative operator and variable weighting of the first and second derivatives of the brightness profile. The results of the experimental algorithm were compared to those of the conventional parent edge detection algorithm with fixed parameters. Dynamic adjustment of the edge-detection algorithm parameters was found to improve measurements of small (lt;0.8-mm) luminal diameters as evidenced by an intercept of +.07 mm for the algorithm with variable weighting compared to +0.21 mm for the parent algorithm with fixed weighting. A slope of <1 was found for both the parent and experimental algorithms with subsequent underestimation of large luminal diameters. Systematic errors in a QCA system can be identified and corrected by the execution of objective in vivo validation studies and the consequent refinement of edge-detection algorithms. The overestimation of small luminal diameters may be overcome by the incorporation of a dynamic edge-detection algorithm. Further refinements in edge-detection algorithms will be required to address the issue of underestimation of large luminal diameters before the absolute values derived from QCA measurements can be considered accurate over the full range of clinically encountered luminal diameters. © 1995 Wiley-Liss, Inc.     

Therapy of stomach ulcer--a comparison between the low dosage antacid hydrotalcite and ranitidine--results of a randomized multicenter double-blind study. Talcivent Study Group]

In a 8 week double-blind randomized multicenter trial in 159 patients with benign gastric ulcer the efficacy of hydrotalcite vs. ranitidine in expediting ulcer healing and in achieving pain relief was determined. 79 patients received hydrotalcite 1000 mg q.i.d. as tablets equalling a total neutralizing capacity of 111.2 mval and 80 patients received ranitidine (300 mg at night). Endoscopically controlled healing rates after 4 weeks of therapy amounted to 41.8% with hydrotalcite and 53.8% with ranitidine. After 8 weeks both regimen showed significant equivalent healing rates (hydrotalcite: 81.0%, ranitidine: 78.8%, p < 0.003). Ulcer pain decreased parallel in both groups. By the end of therapy 92.4% of the patients treated with hydrotalcite and 86.3% of those receiving ranitidine were free of pain. Incidence of helicobacter pylori in antral mucosal biopsies was not influenced by both treatments. We conclude that an 8-week treatment with low dose hydrotalcite therapy is as effective as ranitidine in healing benign gastric ulcers and achieving pain relief.