Factor V Quebec revisited

Factor V Quebec has been described as a bleeding disorder that exhibits an autosomal dominant inheritance pattern and presents severe bleeding after trauma. Two members of a fourth-generation (IV.13 and IV.15) Canadian family have been studied in detail and are the subject of this report. Their clinical presentations and histories have been described previously (Tracy et al: J Clin Invest 74:1221, 1984). Persistent abnormalities include mild thrombocytopenia and defective platelet factor V. Plasma factor V is present at near normal concentration and is fully functional. Thus, the bleeding diathesis appears to reflect the absence of platelet factor V activity. The recent report (Hayward et al: Blood 84:110a, 1994 [suppl, abstr]) of multimerin deficiency in these individuals led us to reevaluate these patients. Western blot analyses of platelet lysates developed with a variety of monoclonal antibodies show that the alpha-granule proteins, fibrinogen, von Willebrand factor, factor V and osteonectin are decreased in concentration and significantly degraded in the platelets of these patients. Thrombospondin, while not degraded, is substantially decreased. In contrast, platelet factor 4 and beta-thromboglobulin do not appear to be affected. These observations suggest that the alpha- granules are correctly assembled but the contents are subsequently subjected to proteolytic degradation. The results indicate that factor V Quebec disorder is probably associated with a generalized defect that leads to degradation of most proteins of the alpha-granules.     

Low incidence of pseudomembranous colitis associated with antibiotics at a general hospital in Lima

Clostridium difficile is associated to episodes of diarrhea related to the use of antibiotics in general hospitals. The aim of this study has been to determine the incidence of this complication among the patients admitted in a 400 bed general hospital in Lima, Perú; we registered every day, in all the wards of the hospital, the presence of diarrhea in patients under antibiotic treatment. In every patient with diarrhea we investigated the presence of cytotoxin and cultivated for C. difficile in the feces. Only 25 patients presented diarrhea and none of them showed inflammatory changes in the endoscopic exploration. Only one patient presented positive cytotoxin with negative culture. In the control group of 41 new-born, asymptomatic infants, already on breast-feeding there were 27 (65.8%) culture and/or cytotoxin positive. We conclude that in our adult population colitis due to C. difficile, associated to antibiotic therapy is an infrequent disease.     

Four categories of gamma-globin gene triplications: DNA sequence comparison of low G gamma and high G gamma triplications

The human fetal gamma chains are produced by closely linked G gamma and A gamma genes, and unequal crossing over between them leads to gamma gene deletions and triplications. Nine gamma gene triplications from seven ethnic groups were analyzed for G gamma and hemoglobin F (Hb F) values of heterozygotes and for the presence of polymorphic XmnI restriction sites 5' to the gamma genes. Four categories of triplication were found: I had low G gamma and low Hb F values and lacked XmnI sites 5' to the three gamma genes [---]. II had high G gamma and slightly elevated Hb F values but was also [---]. III was similar to II, except that XmnI was [+--]. IV had very high G gamma and slightly elevated Hb F values, and XmnI was [++-]. One case each of triplications I and IV were cloned into Charon 35. For both, the two 5' gamma gene code for G gamma chain, while the 3' gamma gene codes for A gamma chain. DNA sequencing showed that the unequal crossover occurred between 472 and 398 base pairs (bp) 5' to the gamma gene Cap sites (- 472 and -398) for the type IV triplication and between -271 and codon 136 for the type I triplication. In addition, type I had a 4-bp deletion of AGCA from -225 to -222. The high G gamma values of the type IV triplication are explained by its -G gamma-G gamma-A gamma-gene arrangement and the XmnI sites 5' to the G gamma genes. We hypothesize that the low G gamma value of the type I triplication, which is also -G gamma-G gamma-A gamma-, is due to inactivation of the middle G gamma gene by the AGCA deletion at -225 to -222.     

Abnormal function of the bone marrow microenvironment in chronic myelogenous leukemia: role of malignant stromal macrophages

The bone marrow microenvironment supports and regulates the proliferation and differentiation of hematopoietic cells. Dysregulated hematopoiesis in chronic myelogenous leukemia (CML) is caused, at least in part, by abnormalities in CML hematopoietic progenitors leading to altered interactions with the marrow microenvironment. The role of the microenvironment itself in CML has not been well characterized. We examined the capacity of CML stroma to support the growth of long-term culture-initiating cells (LTC-IC) obtained from normal and CML marrow. The growth of normal LTC-IC on CML stroma was significantly reduced compared with normal stroma. This did not appear to be related to abnormal production of soluble factors by CML stroma because normal LTC- IC grew equally well in Transwells above CML stroma as in Transwells above normal stroma. In addition, CML and normal stromal supernatants contained similar quantities of both growth-stimulatory (granulocyte colony-stimulating factor (CSF), interleukin-6, stem cell factor, granulocyte-macrophage CSF, and interleukin-1 beta) and growth- inhibitory cytokines (transforming growth factor-beta, macrophage inflammatory protein-1 alpha, and tumor necrosis factor-alpha). The relative proportion of different cell types in CML and normal stroma was similar. However, polymerase chain reaction and fluorescence in situ hybridization studies showed the presence of bcr-abl-positivo cells in CML stroma, which were CD14+ stromal macrophages. To assess the effect of these malignant macrophages on stromal function, CML and normal stromal cells were separated by fluorescence-activated cell sorting into stromal mesenchymal cell (CD14-) and macrophage (CD14+) populations. CML and normal CD14- cells supported the growth of normal LTC-IC equally well. However, the addition of CML macrophages to normal or CML CD14- mesenchymal cells resulted in impaired progenitor support. This finding indicates that the abnormal function of CML bone marrow stroma is related to the presence of malignant macrophages. In contrast to normal LTC-IC, the growth of CML LTC-IC on allogeneic CML stromal layers was not impaired and was significantly better than that of normal LTC-IC cocultured with the same CML stromal layers. These studies demonstrate that, in addition to abnormalities in CML progenitors themselves, abnormalities in the CML marrow microenvironment related to the presence of malignant stromal macrophages may contribute to the selective expansion of leukemic progenitors and suppression of normal hematopoiesis in CML.     

Absence of brain involvement and factors related to positive serology in a prospective series of 61 cases with pulmonary hydatid disease

A prospective series of 65 patients with surgically confirmed lung cystic hydatid disease was evaluated in terms of their radiologic characteristics, serologic response, and presence of cysts in other organs. Cysts were mostly single and located in lower lung lobes. Liver compromise was found in 34% of the patients. Despite a systematic search, no patient showed brain cysts in this series. Twelve patients had previous hydatid disease: six in the liver and eight in the lung (two had involvement of both organs in the past). Serology using bovine cyst fluid in an immunoblot assay was 85% sensitive. Serologic response was not associated with number or cyst or compromise of other organs but was clearly associated to the presence of at least one complicated cyst. Cyst status in terms of complications should be described to allow appropriate assessment of serologic evaluations.     

Short report: transient antibody response in Taenia solium infection in field conditions-a major contributor to high seroprevalence

The discordance between extremely high seroprevalence of Taenia solium antibodies in disease-endemic populations, relatively few symptomatic cases of neurocysticercosis, and high background levels of putatively inactive brain lesions (mainly calcifications) in seronegative controls have confused researchers, clinicians, and epidemiologists in the last decade. We reviewed longitudinal serologic data from general population serosurveys in 3 different disease-endemic areas of Peru and Colombia and found that approximately 40% of seropositive people were seronegative when resampled after 1 year (3 surveys) or after 3 years (1 survey). Transient antibodies may have significant implications for the epidemiology of and immunity to this disease.     

Low prevalence of gastric metaplasia in the duodenal mucosa in Peru.

We compared the prevalence of gastric metaplasia of the duodenal mucosa (GM) and its characteristics in 204 Peruvian patients from a low socioeconomic level with the corresponding prevalence reported in dyspeptic patients from a developed country, the United Kingdom. Gastric metaplasia was significantly less prevalent in the Peruvian than in the United Kingdom series. However, when present, GM was not significantly different in extent or frequency of colonization by Helicobacter pylori or association with active duodenitis, despite a higher prevalence of H. pylori-associated gastritis. Hypochlorhydria was markedly more frequent in the Peruvian than in the United Kingdom series. The finding of a low prevalence of H. pylori-colonized GM in patients with previously reported low prevalence of duodenal ulcer gives further support to a pathogenic link between both conditions.     

Interleukin-1 activates phospholipase A2 in human synovial cells

Interleukin-1 (IL-1) treatment of synovial cells from rheumatoid arthritis and osteoarthritis patients resulted in a dose-dependent secretion of phospholipase A2 (PLA2). IL-1 also stimulated prostaglandin E2 and plasminogen activator synthesis, in parallel with PLA2 activation; all 3 were detectable within 6 hours of IL-1 treatment and peaked by 24 hours. Synovial cell PLA2 required calcium (5 mM) and a neutral pH (7.5) for maximal activity and appears similar to the PLA2 in synovial fluid, which has been described previously. We conclude that PLA2 can be induced by IL-1, and its secretion may contribute significantly to the inflammatory actions of IL-1.     

Hookworm disease: host-pathogen biology

The hallmark of hookworm infection, a common helminthic disease, is iron deficiency anemia. The development of anemia is dependent on the intensity of infection, the species of hookworm, and the ability of the host to resist infection and to maintain adequate stores of iron. When conditions are appropriate, the incidence of anemia caused by hookworm is high and has a significant economic impact since it results in a reduction of worker productivity. Loss of blood is caused by direct ingestion of red cells and by tissue trauma produced by worm attachment and feeding. This focal trauma may involve multiple villi and is characterized by local hemorrhage, tissue cytolysis, and neutrophilic response. Although focal intestinal lesions are apparent, their significance is questionable since diffuse mucosal changes are absent in intestinal biopsies of patients with heavy hookworm infection. Short-range control measures protecting against hookworm infection have not succeeded. Development of a vaccine against hookworm infection in humans is problematic since functional protective immunity in humans has not yet been demonstrated and no suitable animal model of hookworm infection in humans is available. At present, the most effective method of intervention appears to be supplementation of food staples with iron.     

Helicobacter pylori Infection in Infants and Toddlers in South America: Concordance between [13C]Urea Breath Test and Monoclonal H. pylori Stool Antigen Test

Accurate noninvasive tests for diagnosing Helicobacter pylori infection in very young children are strongly required. We investigated the agreement between the [¹³C]urea breath test ([¹³C]UBT) and a monoclonal ELISA (HpSA) for detection of H. pylori antigen in stool. From October 2007 to July 2011, we enrolled 414 infants (123 from Brazil and 291 from Peru) of ages 6 to 30 months. Breath and stool samples were obtained at intervals of at least 3 months from Brazilian (n = 415) and Peruvian (n = 908) infants. [¹³C]UBT and stool test results concurred with each other in 1,255 (94.86%) cases (kappa coefficient = 0.90; 95% confidence interval [CI] = 0.87 to 0.92). In the H. pylori-positive group, delta-over-baseline (DOB) and optical density (OD) values were positively correlated (r = 0.62; P < 0.001). The positivity of the tests was higher (P < 0.001; odds ratio [OR] = 6.01; 95% CI = 4.50 to 8.04) in Peru (546/878; 62.2%) than in Brazil (81/377; 21.5%) and increased with increasing age in Brazil (P = 0.02), whereas in Peru it decreased with increasing age (P < 0.001). The disagreement between the test results was associated with birth in Brazil and female gender but not with age and diarrhea. Our results suggest that both [¹³C]UBT and the stool monoclonal test are reliable for diagnosing H. pylori infection in very young children, which will facilitate robust epidemiological studies in infants and toddlers.