Hypothesis: myelodysplastic syndromes may have a viral etiology

The autonomic nervous system plays a significant role in liver physiology and pathology. The aim of the present study was to investigate peptidergic nerve fibres in the liver of patients with malignant gastrointestinal tumors that are not metastasizing in this organ. Using light and electron microscopic immunohistochemistry, somatostatin (SOM)-, neuropeptide Y (NPY)-, substance P (SP)- and calcitonin gene-related peptide (CGRP)-immunoreactive (IR) nerve fibres (NF) were detected in the portal tract and perisinusoidally. Histologically, the liver showed dilated sinusoids, filled with lymphoid cells, and scarcely marked perisinusoidal fibrosis. Neuropeptide-IR NF were found in close contact with hepatic sinusoids. Numerous IR varicosities were detected in the sinusoidal wall. We discuss the origin and role of these NF in the liver. Probable quantitative changes in peptidergic NF ensue the inflammatory reaction in sinusoids in malignant gastrointestinal tumors. This could also reflect the increased exposure of the liver to toxic substances in the portal blood flow.     

Diagnosis, classification, and cytogenetics of myelodysplastic syndromes

BACKGROUND AND OBJECTIVE: The diagnosis of myelodysplastic syndromes (MDS) is essentially morphological and based on the presence of dysplastic features in the peripheral blood and bone marrow. The French-American-British (FAB) Cooperative Group proposed a classification based on easily obtainable laboratory information. In spite of some limitations, the FAB criteria have been useful for a long time. Currently, the recognition of other distinct morphological MDS subgroups such as hypocellular MDS and MDS with myelofibrosis, the increasing incidence of MDS in children as well as that of therapy-related MDS, and the finding of specific chromosomal alterations associated with different morphological features, reveal the insufficiency of this classification. The aim of the present review is to examine some new aspects of the diagnosis, classification, and cytogenetics of MDS. EVIDENCE AND INFORMATION SOURCES: The authors of this review have been actively working and contributing original papers on MDS for the last 15 years. They also organized or participated in the Fourth International Symposium on MDS (Barcelona, April 24-27, 1997). In addition, the present review critically examines relevant articles and abstracts published in journals covered by the Science Citation Index and Medline. STATE OF THE ART AND PERSPECTIVES: Most of investigators working on MDS tend to integrate morphology and cytogenetics in the diagnosis and classification of these disorders. FAB criteria remain useful particularly for patients with not available cytogenetic study. Refractory cytopenia with multilineage dysplasia should be considered as a new MDS subtype. Some authors propose considering all patients with more than 20% of blast cells in peripheral blood or bone marrow as having acute leukemia. Chronic myelomonocytic leukemia with myeloproliferative features may be included among chronic myeloproliferative disorders. MDS with myelofibrosis is recognized as a new MDS subtype. Therapy-related MDS (t-MDS) should be classified according to the involved agents. Finally, besides including chromosomal abnormalities in the diagnosis (e.g., RAEB with trisomy 8), several cytogenetic abnormalities such as deletion 5q and deletion 17q, associated to specific clinical-morphological features, should be of help to identify new MDS syndromes.     

Etiopathogeny, prognosis and therapy of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a heterogeneous and common group of clonal hematological disorders characterized by cytopenias, dysplastic changes of hematopoietic cells, and a high rate of transformation into acute myeloblastic leukemia (AML). MDS provide a clinical model for studying the emergency and progression of malignancy. The initiating events leading to MDS remain almost unknown. Imbalance of proliferative and differentiating capabilities of progenitor hematopoietic cells along with abnormalities in the normal process of apoptosis are involved in both the pathogenesis of MDS and transformation into AML. Multiple genomic lesions, comprising oncogene activation and tumor-suppressor gene inactivation, are probably required. Alkylating agents, cytotoxic drugs targeting topoisomerase II and benzene are the only clear etiological factors identified. Advanced age and great prognostic variability, not explained by the FAB subtype, complicates the design and analysis of clinical trials and therapy-planning. The use of recently developed prognostic scores for selecting the best treatment according to the expected risk is encouraged. In most patients therapy is unsatisfactory. At present, bone marrow transplantation is considered as the only curative approach. A better knowledge of the pathobiology of MDS should be valuable to develop new, more rationale and effective therapies.     

Cytogenetics of myelodysplastic syndromes

The authors review the main cytogenetic abnormalities encountered in MDS particularly del 5q, -7, +8, and complex abnormalities. Their presence may be useful to the diagnosis of MDS in difficult cases. Their prognostic value is important, and cytogenetics have recently been included in prognostic scores in MDS. Knowledge of recurrent chromosomal rearrangements is finally a first step in the discovery of genes implicated in the pathogenesis of MDS.     

RAS and the myelodysplastic syndromes

RAS genes have been implicated in several different malignancies. The mechanism of activation in most cases has been due to point mutations at critical domains responsible for guanine nucleotide binding. These changes alter the conformation of the protein resulting in insensitivity of the protein to the GTPase activating protein which normally hydrolyses the active p21RAS GTP-bound form to the inactive GDP-bound form. RAS genes have potent effects on the differentiation and proliferation program of cells. The mechanism induced depends on the context in which RAS is found as well as its mutational status and indeed which RAS gene family member is involved. RAS mutations have been described early in the disease process in haematologically normal individuals at risk of mutations induced by either occupational hazard exposure, such as benzene, or of secondary disease after chemotherapy for a previous malignancy. It also been associated with disease progression from myelodysplasia (MDS) to acute myelogenous leukaemia (AML), but it has also been described to be lost upon disease progression, thus showing that RAS mutations are unlikely to be initiating events or at least not required for maintenance of disease. As RAS appears to be involved in primary and secondary myeloid leukaemias, it is a good candidate for gene targeted therapeutic intervention. Studies to target RAS either directly or indirectly by interfering in the RAS pathway are underway. Clinical trials with a peptide RAS vaccine are also ongoing in solid tumours. This report seeks to review the evidence for RAS involvement as oncogenes, focusing on MDS, the reasons as to why the hot spots of codons 12/13 and 61 are particularly potent in activating the transformation potential of RAS and the different approaches being undertaken to translate laboratory findings into therapeutic reality.     

Hospital-acquired pneumonia: epidemiology, etiology, and treatment

Despite improvements in diagnosis, treatment, and prevention, hospital-acquired pneumonia (HAP) remains the number one cause of nosocomial mortality. This article reviews the current knowledge regarding the incidence, epidemiology, and causes of HAP, with the appreciation that the available information is incomplete and that controversies are common, and thus the authors provide a rational approach to the initial management of HAP in immunocompetent adults. A discussion of therapy and what to do with patients who do not respond to the empiric therapy are included. The American Thoracic Society (ATS) statement on HAP has served as a foundation for this review but has been supplemented by newer literature that was not available when the ATS statement was developed.     

Telomere, telomerase and cytogenetic changes in myelodysplastic syndromes

Myelodysplastic syndrome (MDS) is a heterogenous but clonal disorder characterized by cytopenia and dysplastic features. Telomere length in MDS vary but some of them show shortened telomeres. Telomerase activity in MDS also vary but about 60% of them show slightly elevated telomerase activity. According to the disease progression of MDS, MDS patients categorize into 3 groups, i.e., (1) normal telomere length before and after disease progression, (2) short telomere length before and after progression, and (3) shortened telomere with disease progression. Telomerase change with disease progression is not obscure, indicating impairment of telomere dynamics in MDS. These observations may indicate that some MDS show telomerase upregulation possible due to telomere shortening, while the another pathway without telomerase upregulation associated with complex chromosome changes may link to the pathogenesis of MDS.     

Prognostic classification in myelodysplastic syndromes

Factors for predicting the prognosis of myelodysplastic syndromes (MDS) have been widely used over the last few years. The proportion of bone marrow blasts, number and severity of cytopenias, and cytogenetic abnormalities are the main prognostic factors and can be used in combination to determine prognostic scores capable of predicting the outcome with fairly high accuracy. Molecular biology parameters, such as RAS and p53 mutations, can also be of assistance in establishing a prognosis. Factors that predict responsiveness to therapy are usually the same as those that predict survival. Current prognostic scores are unable to identify the minority of patients who will have very long survivals and therefore require no treatment.     

The molecular basis of myelodysplastic syndromes

Rabbit lenses expressing spontaneous oscillations in translens short-circuit current (Isc) are obtained somewhat frequently, with this phenomenon observed in approximately 30% of isolated lenses as described earlier (Exp. Eye Res. 61, 129-140, 1995). Since pharmacological protocols to consistently elicit Isc oscillations were not found, characterizations of the underlying transport processes have been limited to the application of various inhibitors on the spontaneous phenomenon. The present report extends the initial observations by confirming that oscillations are immediately inhibited upon the anterior addition of the Ca2+ channel blocker nifedipine (10 microM), and by demonstrating that other treatments which should affect epithelial Ca2+ homeostasis are also inhibitory (e.g., Bay K 8644 (10 microM), diltiazem (10 microM), EGTA (2 mm), and Ca2+-free media). Furthermore, Isc oscillations are immediately inhibited by the K+ channel blocker, Ba2+, but not by the Na+-K+ pump inhibitor, ouabain. The intracellular Ca2+ mobilizing agents thapsigargin (0.1 microM) or acetylcholine (1 microM) modified but did not permanently inhibit the oscillations, confirming earlier observations. At 50 microM, however, acetylcholine addition was inhibitory, but reversible, for oscillations restarted upon its subsequent removal. In addition, lens oscillations were also characterized under open-circuit conditions with microelectrodes inserted in the superficial cells near the equator of lenses isolated in a divided chamber. The potential difference (PD) across each lens face was recorded, as was the translens PD (PDt), which equals the difference between the PDs across each lens surface. Oscillations in PDt were obtained in 7 of 26 lenses. The oscillations arose only from an oscillation in the PD across the anterior face (PDa). While PDa and PDt oscillated with the same amplitude (approximately 12 mV) and period (approximately 70 sec), the PD across the posterior surface remained stable. During these oscillations the conductance of the anterior surface was maximal at the most positive voltage of the anterior bath with respect to the lens interior (46 mV), whereas, minimal conductance occurred at the least positive PDa (34 mV). Overall, these observations are consistent with the likely presence of voltage-operated Ca2+ channels in parallel with various Ca2+-sensitive K+ channels in the epithelial basolateral membrane. A model to explain the oscillatory pattern across the anterior face while the PD across the posterior face remains unaltered is presented.     

Molecular abnormalities and clonality in myelodysplastic syndromes

Few genes have a proven role in the pathogenesis of myelodysplastic syndromes (MDS). The most common abnormalities involve the RAS genes, most notably the N-RAS gene, and are present in 10% of cases at diagnosis and in 30% to 40% during the course of the disease. Mutations of the p53 are found in 5% to 10% of cases. Mutations of the cFMS genes are less common, abnormalities of the NF1 genes seem to occur only in children, and abnormalities of the RB genes are exceedingly rare. A few instances of t(5;12) or t(3;21) translocation have been demonstrated, and their study has provided evidence that the TEL, EVI1, MDS1, and AML1 genes are involved in some cases of MDS. The presence in MDS of recurrent chromosome 7, 5q, and 20q deletions suggests that these chromosomal segments may bear tumor suppressor genes involved in MDS. The gene(s) involved remain(s) to be identified. Clonality studies have shown that stem cell involvement usually occurs at the myeloid level and that normal multipotent stem cells persist in many patients with MDS. This opens up the promising possibility that transplantation of autologous multipotent stem cells may be an effective therapeutic approach.     

Galactorrhea-amenorrhea syndromes: etiology and treatment

Clinical and renal morphologic studies are reported in a 3 1/2 month old infant with congenital syphilis and nephrotic syndrome. Renal lesions were consistent with membranous proliferative glomerulonephritis, and the presence of glomerular deposits of IgM, C3, and of less intensity of IgE and fibrin, were demonstrated by means of immunofluorescence. These findings identify the renal lesion as an immune glomerulopathy. A therapeutic course of penicillin resulted in resolution of clinical manifestations without any evidence of persistent renal damage.     

Pathogenesis of acute coronary syndromes

Coronary artery diseases may categorized into asymptomatic disease, angina pectoris, myocardial infarction, chronic heart failure, and sudden coronary death. Unstable angina, acute myocardial infarction, and sudden cardiac death are known as the acute coronary syndromes. Coronary atheroma is unstable in the patients with acute coronary syndromes. Stable plaques will be unstable when dynamic alterations occur. The alterations are plaque rupture, plaque hemorrhage, coronary thrombosis and vasospasm. They act each other. We analysed the histopathology of coronary arteries who died of acute myocardial infarction in 85 cases. It showed that the risk factors of plaque rupture are clusters of form cells, eccentric plaque with soft lipid rich core, and thinning of fibrous cap in atheroma. Most of these cases ruptured at edge of the atheroma.     

Surface marker abnormalities in myelodysplastic syndromes

BACKGROUND AND OBJECTIVE: The myelodysplastic syndromes (MDS) are clonal stem cell disorders associated with a variety of abnormalities of mature and maturing cells, including surface antigen abnormalities. Granulocytes and monocytes function as members of the immune system. Surface antigens serve as biological sensors allowing various cells to interact with different stimuli. Abnormalities of surface antigens may be associated with defective cell function and may indicate a more severe or more advanced stage of the disease. INFORMATION SOURCES: The author has a great interest in bone marrow changes in MDS and has several previous publications in this field. In addition, relevant articles published since 1966 were retrieved using Medline of English literature and were included. STATE OF THE ART AND PERSPECTIVES: Several surface antigens in MDS have shown abnormal expression either in the intensity of fluorescence or the percentage of positive cells. These abnormalities include increased, decreased or lineage-aberrant expression. Abnormalities of several surface markers have prognostic significance. MDS patients with a low percentage of bone marrow cells expressing CD11b had a higher risk of evolution to acute myeloid leukemia and shorter survival compared to patients with more than 53% of marrow cells expressing CD11b (29 weeks versus 160 weeks). On the other hand, an increased percentage of bone marrow cells expressing early or immature markers, such as CD 13, CD33, CD34 and HLA-DR, has been associated with a worse outcome and with progression to a higher risk MDS or to acute myeloid leukemia. However, there are numerous discrepancies and inconsistencies in the literature when reviewing surface marker changes in MDS. These discrepancies may be related, at least in part, to the presence of an intracellular storage compartment of numerous surface antigens in the granulocytes and monocytes. Because of these storage pools, the techniques of preparing more mature granulocytes and monocytes, such as density gradient separation, and the interpretation of results must be carefully evaluated. Furthermore, various methods have been used to express abnormal results including percentage of positive or negative cells, fluorescent intensity (FI) of individual patients or a group of patients using a mean fluorescent channel (256 or 1024 channel mode), and finally the expression of FI as molecules of equivalent soluble fluorochromes or antibody binding capacities. Several mechanisms may be involved in the abnormal expression of surface antigens in MDS including defective granulopoiesis, defective intracellular storage pool, abnormal membrane of cytoplasmic granules, and the effect of high levels of marrow cytokines such as tumor necrosis factor alpha and transforming growth factor-beta. Standardization of the methods of preparing and studying mature and maturing granulocytes and monocytes in MDS has to be achieved in order to produce comparable results, thus allowing surface marker studies to be utilized as diagnostic and prognostic tools in MDS.     

Prognostic factors and scoring systems in myelodysplastic syndromes

The treatment of peptic ulcers has been revolutionized by the discovery that Helicobacter pylori (H. pylori) bacteria is a causative agent for ulcer formation. However, when patients present with dyspepsia or epigastric discomfort, more than 80% of patients will not have ulcer disease and empiric treatment of H. pylori is not recommended for these patients. Eradication of H. pylori has not been demonstrated to improve the symptoms of non-ulcer dyspepsia compared with non-ulcer dyspepsia patients treated with placebo. Therefore, we recommend that patients should first be evaluated for peptic ulcers with endoscopy or upper gastrointestinal series before the diagnosis and treatment of H. pylori. Generally, the treatment of H. pylori should be limited to patients with peptic ulcers, mucosal-associated lymphoid tissue lymphomas, and gastric cancers. Most diagnostic tests for H. pylori, including quantitative IgG antibody, urea breath tests, rapid urease tests (CLO), tests of gastric mucosal biopsies, and staining of gastric mucosal biopsies, have equivalent diagnostic characteristics. Therefore, the choice of diagnostic test for H. pylori should be based on cost, ease of use, and lack of complications. Multiple antibiotic regimens are available for the treatment of H. pylori. Triple antibiotic therapy is the least expensive but has the highest rate of side effects and the least compliance. Combining a proton pump inhibitor with clarithromycin and another antibiotic will eradicate H. pylori with fewer side effects and better compliance but this is the most expensive antibiotic regimen.     

Treatment with growth factors in myelodysplastic syndromes

In myelodysplastic syndromes (MDS), pancytopenia leads to a high risk of infectious and hemorrhagic complications. The progression to acute myeloid leukemia adds to morbidity and mortality. While transfusions of red blood cells and platelets are still a cornerstone of the therapy, the clinical use of recombinant hematopoietic growth factors has enlarged the range of therapeutic applications in patients with MDS. It is possible to reverse neutropenia by administration of G-CSF (granulocyte colony stimulating factor) or GM-CSF (granulocyte-monocyte colony stimulating factor). In the case of a severe infection, therapeutic administration of G-CSF together with antibiotics might be justified in otherwise neutropenic MDS patients. Since especially patients with only slight impairment of erythropoiesis and no transfusion dependency have the highest response rates but need erythropoietin (EPO) the least, pharmacoeconomic analyses are urgently needed. Controlled randomized trials will have to ascertain wether combinations of EPO with G-CSF or GM-CSF are of benefit. Clinical studies with thrombopoietin (megakaryocyte growth and differentiation factor) have to be initiated to find out whether thrombocytopenia in MDS can be reversed.