Thymus transplantation restores the repertoires of forkhead box protein 3 (FoxP3)+ and FoxP3- T cells in complete DiGeorge anomaly.

The development of T cells with a regulatory phenotype after thymus transplantation has not been examined previously in complete DiGeorge anomaly (cDGA). Seven athymic infants with cDGA and non-maternal pretransplantation T cell clones were assessed. Pretransplantation forkhead box protein 3 (Foxp3)(+) T cells were detected in five of the subjects. Two subjects were studied in greater depth. T cell receptor variable ß chain (TCR-Vß) expression was assessed by flow cytometry. In both subjects, pretransplantation FoxP3(+) and total CD4(+) T cells showed restricted TCR-Vß expression. The development of naive T cells and diverse CD4(+) TCR-Vß repertoires following thymic transplantation indicated successful thymopoiesis from the thymic tissue grafts. Infants with atypical cDGA develop rashes and autoimmune phenomena before transplantation, requiring treatment with immunosuppression, which was discontinued successfully subsequent to the observed thymopoiesis. Post-transplantation, diverse TCR-Vß family expression was also observed in FoxP3(+) CD4(+) T cells. Interestingly, the percentages of each of the TCR-Vß families expressed on FoxP3(+) and total CD4(+) T cells differed significantly between these T lymphocyte subpopulations before transplantation. By 16 months post-transplantation, however, the percentages of expression of each TCR-Vß family became significantly similar between FoxP3(+) and total CD4(+) T cells. Sequencing of TCRBV DNA confirmed the presence of clonally amplified pretransplantation FoxP3(+) and FoxP3(-) T cells. After thymus transplantation, increased polyclonality was observed for both FoxP3(+) and FoxP3(-) cells, and pretransplantation FoxP3(+) and FoxP3(-) clonotypes essentially disappeared. Thus, post-transplantation thymic function was associated with the development of a diverse repertoire of FoxP3(+) T cells in cDGA, corresponding with immunological and clinical recovery.

Decreased plasma cytokines are associated with low platelet counts in aplastic anemia and immune thrombocytopenic purpura.

BACKGROUND: We previously found plasma levels of CD40 ligand (CD40L), chemokine (C-X-C motif) ligand 5 (CXCL5), chemokine (C-C motif) ligand 5 (CCL5) and epidermal growth factor (EGF) to be low in aplastic anemia (AA) patients and to be correlated with platelet count. OBJECTIVES: To study the association of CD40L, CXCL5, CCL5 and EGF with platelets. METHODS: We measured cytokines in the plasma of immune thrombocytopenic purpura (ITP) and AA patients using the Luminex assay and confirmed the results in a mouse model and in vitro experiments. RESULTS: Both ITP and AA showed similarly low levels of CD40L, CXCL5, CCL5 and EGF, compared with healthy controls. In ITP, levels of these proteins were significantly greater in patients with higher platelet counts than in those with lower platelet counts. In a murine thrombocytopenia model, levels of CD40L, CXCL5, CCL5 and EGF decreased with platelet count after immune-mediated destruction, while the cytokine levels increased when the platelet count recovered. In vitro, concentrations of these cytokines in the supernatants of platelet suspensions were proportional to platelet numbers, and levels in sera prepared by simple blood coagulation were equivalent to those in platelet-rich plasma-converted sera. mRNA expression for CXCL5, CCL5 and EGF was higher in platelets than in megakaryocytes, peripheral blood mononuclear cells, granulocytes and non-megakaryocytic bone marrow cells. CONCLUSIONS: Plasma CD40L, CXCL5, CCL5 and EGF are mainly platelet-derived, suggesting a role of platelets in immune responses and inflammation. Measurement of CD40L, CXCL5, CCL5 and EGF in human blood allowed testable inferences concerning physiology and pathophysiology in quantitative platelet disorders.

Short telomeres result in chromosomal instability in hematopoietic cells and precede malignant evolution in human aplastic anemia.

In cell and animal models, telomere erosion promotes chromosomal instability via breakage-fusion-bridge cycles, contributing to the early stages of tumorigenesis. However, evidence involving short telomeres in cancer development in humans is scarce, epidemiological and indirect. Here we directly implicate telomere shortening as a critical molecular event for malignant evolution in aplastic anemia (AA). Patients' telomere lengths at diagnosis of AA, while comparable to age-matched controls, inversely correlated with the probability of developing a cytogenetically abnormal clone. A significantly increased number of telomere signal-free chromosomal ends and chromosomal numerical and structural abnormalities were observed in bone marrow cells of patients with shorter telomeres in comparison with patients with longer telomeres and healthy subjects. The proportion of monosomy-7 cells in the bone marrow at diagnosis of AA inversely correlated with telomere length, years before the emergence of an autonomous and clinically detectable abnormal clone. Marrow cells of clinically healthy individuals carrying loss-of-function telomerase mutations and with extremely short telomeres also showed chromosomal instability in vitro. These results provide the first clinical direct evidence in humans that short telomeres in hematopoietic cells are dysfunctional, mediate chromosomal instability and predispose to malignant transformation in a human disease.

Regulatory T-cell depletion does not prevent emergence of new CD25+ FOXP3+ lymphocytes after antigen stimulation in culture.

BACKGROUND: The removal of human regulatory T (T(reg)) cells from a cellular product prior to the induction of a T-cell response has the potential to boost the total yield of antigen (Ag)-specific CD4(+) and CD8(+) T cells. METHODS: We examined the effect of this manipulation on the generation of human anti-cytomegalovirus (CMV) T-cell responses. Furthermore, we examined the clonotypic composition of Ag-specific CD4(+)FOXP3(+) and CD4(+)FOXP3(-) T cells. RESULTS: We found that the immunomagnetic depletion of CD25(+) cells had an unpredictable effect on outcome, with total yields of CMV-specific T cells either increasing or decreasing after the removal of these cells. The depletion of CD25(+) cells both removed a proportion of Ag-specific T cells and failed to eliminate a substantial population of T(reg) cells. Furthermore, using a novel T-cell receptor clonotyping technique, we found that Ag recognition induces the expression of FOXP3 in a proportion of specific T cells; these FOXP3-expressing Ag-specific CD4(+) and CD8(+) T cells were no longer capable of producing inflammatory cytokines. DISCUSSION: The depletion of CD25(+) cells from the starting population has a variable effect on the total yield of Ag-specific T cells, a proportion of which invariably acquire FOXP3 expression and lose effector function.

Stem-cell transplantation for autoimmune diseases.

The use of intensive immunosuppressive treatment coupled with BM stem-cell transplantation (SCT) to treat human autoimmune diseases (AID) follows anecdotal observations of responses of AID to allogeneic SCT and an extensive background of experience with SCT in animals with AID. In the last decade, numerous clinical trials have been initiated to explore a potential benefit of (mainly autologous) SCT in advanced and debilitating cases of rheumatoid arthritis, scleroderma, systemic lupus erythematosis and multiple sclerosis. In this review the etiology of AID and the experimental basis of SCT is presented, together with recent clinical results of SCT for AID. While much has been learned about the risks and benefits of SCT in AID, the underlying mechanisms regulating remission and relapse of AID after treatment remain largely unknown.

Update in internal medicine.

More than 500,000 new medical articles are published every year and available time to keep updated is scarcer every day. Nowadays, the task of selecting useful, consistent, and relevant information for clinicians is a priority in many major medical journals. This review has the aim of gathering the results of the most important findings in clinical medicine in the last few years. It is focused on results from randomized clinical trials and well-designed observational research. Findings were included preferentially if they showed solid results, and we avoided as much as possible including only preliminary data, or results that included only non-clinical outcomes. Some of the most relevant findings reported here include the significant benefit of statins in patients with coronary artery disease even with mean cholesterol level. It also provides a substantial review of the most significant trials assessing the effectiveness of IIb/IIIa receptor blockers. In gastroenterology many advances have been made in the H. pylori eradication, and the finding that the cure of H. pylori infection may be followed by gastroesophageal reflux disease. Some new antivirals have shown encouraging results in patients with chronic hepatitis. In the infectious disease arena, the late breaking trials in anti-retroviral disease are discussed, as well as the new trends regarding antibiotic resistance. This review approaches also the role of leukotriene modifiers in the treatment of asthma and discusses the benefit of using methylprednisolone in patients with adult respiratory distress syndrome, among many other advances in internal medicine.

Stroke: the way things really are.

BACKGROUND: To comply with governmental requirements regarding the validity of therapeutic modalities and for medico-legal purposes, it is important to distinguish between what has been scientifically proven and what is anecdotal in the prevention and management of stroke. SUMMARY OF REVIEW: This review summarizes the evidence for many of the modalities used to prevent stroke in high-risk patients, including antiplatelet drugs, anticoagulants, and endarterectomy, and the limitations of each. Controversial therapeutic modalities for which no scientific proof exists, such as anticoagulation of progressing stroke, are also discussed. The term "standard of care" should apply to modalities proven to be effective by scientifically controlled studies, not because they are used by many physicians. Treatment of acute stroke is still disappointing despite the development of many promising pharmacological strategies in experimental animals. An important part of the reason may be that the window of therapeutic opportunity is much shorter than the usual entry time of patients in most clinical trials. This logistic problem merits serious attention. CONCLUSIONS: Numerous controlled, randomized, multiple-center clinical trials have demonstrated that the efficacy or lack thereof of various therapies directed at preventing or treating stroke can be determined and that anecdotal data may be misleading and harmful. At the least we should be aware of what we know and what we do not.

The biologic basis for the treatment of acute stroke.

This is a review of therapeutic modalities that have been utilized in the treatment of stroke. Each is based upon data obtained from the study of the biologic events that occur during experimentally induced cerebral ischemia in animals. The type of information obtained from these studies could not have been obtained in any other manner. Despite the apparent effectiveness of some of these modalities in modifying stroke in animals, their application to humans with stroke has been disappointingly ineffectual. The delay between onset of stroke symptoms and initiation of treatment is usually several hours or more, which may be too late to rescue ischemic neurons. In order to be effective, treatment will have to be initiated as early as possible (preferably within 1 hour) to take advantage of the biologic window of opportunity. There is evidence that this can be accomplished by proper planning and training of personnel.

Transient ischemic attacks: an update.

This is a review of extant concepts of transient ischemic attacks (TIAs), their definitions, prognostic significance, pathogenesis, physiology, and management. The natural history of TIAs depends upon the risk factors of the population group studied, so that therapeutic trials should be controlled and randomized and not dependent upon published natural history data. A strong association between TIAs and coronary artery disease has now been established. It may be difficult to establish the cause or pathogenesis of TIAs in any given patient in view of the relatively poor correlation between the patient's symptoms and location of arterial plaques. Recent studies have suggested mechanisms aside from impaired perfusion or embolization from carotid plaques or vertebral basilar disease. There are no proven indications for carotid endarterectomy, a procedure which has been excessively used in the United States, but presently ongoing prospective, randomized, controlled multi-center studies will likely resolve this important issue. Neither is there scientific validation for the use of long-term anticoagulants, but data support the efficacy of ASA in reducing the incidence of stroke and myocardial infarction in patients with TIAs.

Dementia due to vascular disease--a multifactorial disorder.

This review was undertaken to evaluate critically the literature pertaining to vascular dementia with the objective of determining a more useful and scientifically supported definition of vascular dementia, its relation to other causes of dementia, and the biologic mechanisms involved in its causation.

Pentoxifylline in acute nonhemorrhagic stroke. A randomized, placebo-controlled double-blind trial.

The efficacy and safety of pentoxifylline were assessed in 297 adult patients with ischemic stroke in a multicenter, double-blind, randomized and placebo-controlled trial. Treatment was started within 12 hours after the stroke onset. Study medication was administered intravenously continuously (16 mg/kg/day, maximum 1,200 mg/day) for 3 days and per os (400 mg t.i.d.) for the remainder of 28 days. Demographic data were comparable, and functional impairment and mortality (pentoxifylline 12%, placebo 10%) were not different between the two groups. Neurologic deficit scores improved from baseline admission scores during the 4-week study in both groups but did not differ between groups at admission or throughout the study except during the first few days when the consciousness level (Days 1 and 2), motor function (Days 1 and 2), cranial nerve function (Days 1-4), and total neurologic deficit scores (Days 1 and 2) were better in the pentoxifylline group than in the placebo group, especially in a subset of patients with severe deficits at admission. Laboratory values and side effects were also comparable between groups. Our study indicates that pentoxifylline can be given safely in patients with acute ischemic stroke. Although pharmacologic effects were present during the first few days, the clinical benefits were small and not sustained.

Small differences in intraischemic brain temperature critically determine the extent of ischemic neuronal injury.

We have tested whether small intraischemic variations in brain temperature influence the outcome of transient ischemia. To measure brain temperature, a thermocouple probe was placed stereotaxically into the left dorsolateral striatum of rats prior to 20 min of four-vessel occlusion. Rectal temperature was maintained at 36-37 degrees C by a heating lamp, and striatal temperature prior to ischemia was 36 degrees C in all animals. Six animal subgroups were investigated, including rats whose intraischemic striatal brain temperature was not regulated, or was maintained at 33, 34, 36, or 39 degrees C. Postischemic brain temperature was regulated at 36 degrees C, except for one group in which brain temperature was lowered from 36 degrees C to 33 degrees C during the first hour of recirculation. Energy metabolites were measured at the end of the ischemic insult, and histopathological evaluation was carried out at 3 days after ischemia. Intraischemic variations in brain temperature had no significant influence on energy metabolite levels measured at the conclusion of ischemia: Severe depletion of brain ATP, phosphocreatine, glucose, and glycogen and elevation of lactate were observed to a similar degree in all experimental groups. The histopathological consequences of ischemia, however, were markedly influenced by variations in intraischemic brain temperature. In the hippocampus, CA1 neurons were consistently damaged at 36 degrees C, but not at 34 degrees C. Within the dorsolateral striatum, ischemic cell change was present in 100% of the hemispheres at 36 degrees C, but in only 50% at 34 degrees C. Ischemic neurons within the central zone of striatum were not observed in any rats at 34 degrees C, but in all rats at 36 degrees C. In rats whose striatal temperature was not controlled, brain temperature fell from 36 to 30-31 degrees C during the ischemic insult. In this group, no ischemic cell change was seen within striatal areas and was only inconsistently documented within the CA1 hippocampal region. These results demonstrate that (a) rectal temperature unreliably reflects brain temperature during ischemia; (b) despite severe depletion of brain energy metabolites during ischemia at all temperatures, small increments of intraischemic brain temperature markedly accentuate histopathological changes following 3-day survival; and (c) brain temperature must be controlled above 33 degrees C in order to ensure a consistent histopathological outcome. Lowering of the brain temperature by only a few degrees during ischemia confers a marked protective effect.

Substantia nigra lesion protects against ischemic damage in the striatum.

The role of striatal dopamine (DA) in mediating ischemic neuronal death was studied in the rat. Two weeks after unilateral substantia nigra lesion, rats were subjected to 20 min of forebrain ischemia by 4-vessel occlusion. Morphological changes and 45Ca uptake were evaluated after 3 days of survival. In the DA-depleted striatum, the degree of ischemic neuronal damage and 45Ca uptake were markedly attenuated compared to the contralateral side. This study is the first to demonstrate that the presence of DA is a prerequisite for the development of ischemic injury in the striatum and that DA depletion protects the striatum from ischemic damage.

Photochemically induced cerebral infarction. II. Edema and blood-brain barrier disruption.

Alterations in the blood-brain barrier to proteins, and regional water and electrolyte content were documented in a rat model of photochemically induced small-vessel thrombosis leading to infarction. Horseradish peroxidase (HRP) or Evans blue was given immediately following a 2-min photochemical sensitization period. At 5 min following irradiation, multifocal sites of peroxidase extravasation were noted within the irradiated area. Ultrastructural examination revealed endothelial cells filled with HRP which in some cases extended into the basal lamina and extracellular spaces. At 15 min, protein leakage was more pronounced within the irradiated zone and reaction product was also apparent within the subarachnoid and perivascular spaces of brain regions remote from the site of irradiation. Widespread staining on the surface of the irradiated hemisphere was apparent in rats perfused 8 h following Evans blue infusion. Water content increased significantly by 15 min within the irradiated zone but not in brain regions remote from this site. Although vasogenic edema is an early event in this stroke model, increases in water content are restricted to the irreversibly damaged site. In contrast, protein tracer escaping from microvessels coursing within the irradiated zone was widely distributed. These findings implicate endothelial barrier dysfunction in the genesis of tissue injury in this model. Morphological evidence for the capability of macromolecules to escape from a site of evolving infarction and to migrate to distances remote from the area of primary microvascular damage is also discussed.