Lipopolysaccharide enhances CD11b/CD18 function but inhibits neutrophil aggregation

Human neutrophils are primed in the presence of complexes of lipopolysaccharide (LPS) with its serum binding protein (LBP) in a manner dependent on CD14. Cellular consequences of priming include increased responsiveness, the upregulation of surface proteins including the adhesive integrin CD11b/CD18 (Mac-1), the increased binding of certain ligands to CD11b/CD18, and the concurrent shedding of the L-selectin homing receptor. Because expression of both CD11b/CD18 and L-selectin is obligatory for formyl peptide-stimulated neutrophil aggregation in vitro (Simon et al, Blood 82:1097, 1993), we have examined the consequences of bacterial endotoxin on the expression of neutrophil adhesive molecules. We observed that the exposure of neutrophils to LPS/LBP, while enhancing the surface numbers and adhesive function of CD11b/CD18 for latex particles, did not induce aggregation. In contrast, as the LPS/LBP concentration increased (ED50 = 30 ng/mL LPS/LBP), the ability of neutrophils to aggregate decreased in parallel with the shedding of L-selectin. Moreover, when L-selectin adhesive activity was blocked by treatment with Fab fragments of Dreg- 200, aggregation was inhibited to an extent roughly proportional to the available L-selection. Blocking of LPS/LBP with CD14-specific monoclonal antibodies suppressed L-selectin shedding and preserved formyl peptide-stimulated aggregation. Taken together, the data suggest that inhibition of neutrophil aggregation by LPS/LBP is related to the expression of L-selectin via CD14 rather than LPS inhibition of CD11b/CD18 function during cellular stimulation.     

Functional differences between CD38- and DR- subfractions of CD34+ bone marrow cells

Several studies have previously demonstrated enrichment in primitive progenitor cells in subfractions of CD34+ bone marrow (BM) cells not expressing CD38 or HLA-DR (DR) antigens. However, no studies have directly compared these two cell populations with regard to their content of primitive and more committed progenitor cells. Flow cytometric analysis of immunomagnetic isolated CD34+ cells demonstrated little overlap between CD34+CD38- and CD34+DR- progenitor subpopulations in that only 12% to 14% of total CD34+DR- and CD34+CD38- cells were double negative (CD34+CD38-DR-). Although the number of committed myeloid progenitor cells (colony-forming units granulocyte- macrophage) was reduced in both subpopulations, only CD34+CD38- cells were significantly depleted in committed erythroid progenitor cells (burst-forming units-erythroid). In single-cell assay, CD34+CD38- cells showed consistently poorer response to single as opposed to multiple hematopoietic growth factors as compared with unfractionated CD34+ cells, indicating that the CD34+CD38- subset is relatively enriched in primitive hematopoietic progenitor cells. Furthermore, CD34+CD38- and CD34+DR- cells, respectively, formed 3.2-fold and 1.6-fold more high proliferative potential colony-forming cell (HPP-CFC) colonies than did unfractionated CD34+ cells. Finally, CD34+CD38-DR- cells were depleted in HPP-CFCs as compared with CD34+CD38+DR+ cells. The results of the present study suggest that both the CD38- and DR- subfractions of CD34+ bone marrow cells are enriched in primitive hematopoietic progenitor cells, with the CD34+CD38- subpopulation being more highly enriched than CD34+DR- cells.     

Bifunctional effects of tumor necrosis factor alpha (TNF alpha) on the growth of mature and primitive human hematopoietic progenitor cells: involvement of p55 and p75 TNF receptors

Tumor necrosis factor alpha (TNF alpha) has previously been reported to have both inhibitory and stimulatory effects on hematopoietic progenitor cells. Specifically, TNF alpha has been proposed to stimulate early hematopoiesis in humans. In the present study we show that TNF alpha, in a dose-dependent fashion, can potently inhibit the growth of primitive high proliferative potential colony-forming cells (HPP-CFCs) stimulated by multiple cytokine combinations. Using agonistic antibodies to the p55 and p75 TNF receptors or TNF alpha mutants specific for either of the two TNF receptors, we show that both receptors can mediate this inhibition. In contrast, the potent stimulation of interleukin-3 (IL-3) plus granulocyte-macrophage colony- stimulating factor (GM-CSF) induced HPP-CFC colony formation observed at low concentrations of TNF alpha (2 ng/mL) was only a p55-mediated event. Moreover, the stimulatory effects of TNF alpha on GM-CSF or IL-3- induced colony formation, as well as the inhibition of G-CSF-induced colony growth, were also exclusively signaled through the p55 TNF receptor. Taken together, our results suggest that the inhibitory effects of TNF alpha on primitive bone marrow progenitor cells are mediated through both p55 and p75 TNF receptors, whereas the p55 receptor exclusively mediates the bidirectional effects on more mature, single factor-responsive bone marrow progenitor cells as well as stimulation of IL-3 plus GM-CSF-induced HPP-CFC colony growth.     

Prognostic discrimination in "good-risk" chronic granulocytic leukemia

The prognostic significance of disease features recorded at the time of diagnosis was examined among 813 patients with Philadelphia chromosome- positive, nonblastic chronic granulocytic leukemia (CGL) collected from six European and American series. The survival pattern for this population was typical of "good-risk" patients, and median survival was 47 mo. There were multiple interrelationships among different disease features, which led to highly significant correlations with survival for some that had no primary prognostic significance, such as hematocrit. Multivariable regression analysis indicated that spleen size and the percentage of circulating blasts were the most important prognostic indicators. These features, and age, behaved as continuous variables with progressively unfavorable import at higher values. The platelet count did not influence survival significantly at values below 700 X 10(9)/liter but was increasingly unfavorable above this level. Basophils plus eosinophils over 15%, more than 5% marrow blasts, and karyotypic abnormalities in addition to the Ph1 were also significant unfavorable signs. The Cox model, generated with four variables representing percent blasts, spleen size, platelet count, and age, provided a useful representation of risk status in this population, with good fit between predicted and observed survival over more than a twofold survival range. A hazard function derived from half of the patient population successfully segregated the remainder into three groups with significantly different survival patterns. We conclude that it should be possible to identify a lower risk group of patients with a 2-yr survival of 90%, subsequent risk averaging somewhat less than 20%/yr and median survival of 5 yr, an intermediate group, and a high- risk group with a 2-yr survival of 65%, followed by a death rate of about 35%/yr and median survival of 2.5 yr.     

Can we measure the ankle-brachial index using only a stethoscope? A pilot study

Background. Ankle-brachial index (ABI) is an excellent methodfor the diagnosis of peripheral arterial disease (PAD) whenit is performed with Doppler. However, this device is not alwaysavailable for primary care physicians. The ABI measured withstethoscope is an easy alternative approach, but have not beenproved to be useful. Objective. To assess the accuracy of the ABI measured usinga stethoscope comparatively to that of the current eligiblemethod for the diagnosis of PAD, the Doppler ABI, and describethe characteristics of this new approach. Methods. We conducted a diagnostic study of ABI measured witha stethoscope and a Doppler probe and compared the results.Eighty-eight patients were accessed by both methods. Results. Mean stethoscope ABI, 1.01 ± 0.15, and meanDoppler ABI, 1.03 ± 0.20, (P = 0.047) displayed a goodcorrelation. Measurements of stethoscope ABI diagnostic accuracyin recognizing a Doppler ABI are described. The comparison ofthis data with the current gold standard method results gavea sensitivity of 71.4% [95% confidence interval (CI), 41.9–91.6]and specificity of 91.0% (95% CI, 81.5–96.6), with predictivepositive value of 62.5% (95% CI, 38.6–81.5) and negativepredictive value of 93.8% (95% CI, 85.2–97.6). The studyaccuracy was 87.7%. The area under the ROC curve was 0.895 (95%CI, 0.804–0.986, P < 0.0001). Conclusions. According to our study, the stethoscope ABI isa useful method to detect PAD and it may be suitable for itsscreening in the primary care setting. Keywords. Ankle-brachial index, peripheral arterial disease, stethoscope.     

Abnormalities of hippocampal surface structure in very mild dementia of the Alzheimer type

To better define the pattern of hippocampal deformity early in the course of Alzheimer's disease, we compared the pattern of hippocampal surface variation in subjects with very mild dementia of the Alzheimer type (DAT) and nondemented subjects. The surface of the hippocampus was divided a priori on a neuroanatomical template into three zones approximating the locations of underlying subfields [Csernansky, J.G., Wang, L., Swank, J., Miller, J.P., Gado, M., McKeel, D., Miller, M.I., Morris, J.C., 2005. Preclinical detection of Alzheimer's disease: hippocampal shape and volume predict dementia onset in the elderly. NeuroImage 25, 783--792]; i.e., a lateral zone (LZ) approximating the CA1 subfield, a superior zone (SZ) approximating the combined CA2, CA3, CA4 subfields and the gyrus dentatus (GD), and an inferior-medial zone (IMZ) approximating the subiculum. Large-deformation high-dimensional brain mapping (HDBM-LD) was used to generate the hippocampal surfaces of all subjects and to register the surface zones across subjects. Average variations within each zone were calculated for the subjects with very mild DAT as compared to the average of the nondemented subjects. After correcting for multiple comparisons, the very mild DAT subjects showed significant inward variation in the left and right LZ, the left and right IMZ, but not in the left and right SZ as compared to nondemented subjects. In logistic regression analyses, inward variation of the left and right LZ or IMZ by 0.1 mm relative to the average of the nondemented subjects increased the odds of the subject being a very mild DAT subject (range-1.18 to 1.57) rather than being a nondemented subject. The odds ratios for the left and right SZ were not significant. These results represent a replication of our previous findings [Csernansky, J.G., Wang, L., Joshi, S., Miller, J.P., Gado, M., Kido, D., McKeel, D., Morris, J.C., Miller, M.I., 2000. Early DAT is distinguished from aging by high-dimensional mapping of the hippocampus. Neurology 55, 1636--1643.] and suggest that inward deformities of the hippocampal surface in proximity to the CA1 subfield and subiculum can be used to distinguish subjects with very mild DAT from nondemented subjects.     

Active tuberculosis and Mycobacterium tuberculosis latent infection in patients with HIV/AIDS

Objectives

Tuberculosis (TB) remains an important disease associated with HIV infection and AIDS in Brazil, even in a setting of free access to antiretroviral therapy (ART) and TB treatment. In previous studies, isoniazid therapy (IT) for latent infection with Mycobacterium tuberculosis (LIMTb) was found to reduce the risk of TB by 62% in patients with a tuberculin test (TT)>5 mm. The objectives of this study were to investigate the occurrence of TB, the prevalence of LIMTb and the coverage of the TT and IT, and to estimate the number of missed opportunities to prevent TB in patients with HIV/AIDS.

Methods

A random sample of patients with HIV/AIDS was selected; data from the medical files were obtained, and a TT was performed in consenting subjects.

Results

In the 203 subjects included in the study, TB occurrence was 13.3%, LIMTb prevalence was 20% and the coverage of the TT and IT was 59.2 and 55%, respectively. Patients with TB had a lower nadir CD4 cell count, but their CD4 recovery was comparable to that of non‐TB patients. Patients with LIMTb always had a higher CD4 cell count.

Conclusions

By expanding the coverage of the TT and IT to nearly 100%, we could more than double the number of prevented cases of TB. TB prevention programmes must be reinforced to reduce the number of missed opportunities for diagnosis, and IT must be improved to reduce TB among patients with HIV/AIDS. Empowering patients with knowledge about TB, the preventive role of IT and the need for an annual TT may be the best way of lowing rates of TB in patients with HIV/AIDS.     

Tracking type specific prevalence of human Papillomavirus in cervical pre-cancer: a novel sampling strategy

ABSTRACT: BACKGROUND: Surveillance designed to detect changes in the type-specific distribution of HPV in cervical intraepithelial neoplasia grade 3 (CIN-3) is necessary to evaluate the effectiveness of the Australian vaccination programme on cancer causing HPV types. This paper develops a protocol that eliminates the need to calculate required sample size; sample size is difficult to calculate in advance because HPV's true type-specific prevalence is imperfectly known. METHOD: A truncated sequential sampling plan that collects a variable sample size was designed to detect changes in the type-specific distribution of HPV in CIN-3. Computer simulation to evaluate the accuracy of the plan at classifying the prevalence of an HPV type as low (< 5%), moderate (5-15%), or high (> 15%) and the average sample size collected was conducted and used to assess its appropriateness as a surveillance tool. RESULTS: The plan classified the proportion of CIN-3 lesions positive for an HPV type very accurately, with >90% of simulations correctly classifying a simulated data-set with known prevalence. Misclassifying an HPV type of high prevalence as being of low prevalence, arguably the most serious kind of potential error, occurred < 0.05 times per 100 simulations. A much lower sample size (21-22 versus 40-48) was required to classify samples of high rather than low or moderate prevalence. CONCLUSIONS: Truncated sequential sampling enables the proportion of CIN-3 due to an HPV type to be accurately classified using small sample sizes. Truncated sequential sampling should be used for type-specific HPV surveillance in the vaccination era.     

Mice deficient in MCT8 reveal a mechanism regulating thyroid hormone secretion

The mechanism of thyroid hormone (TH) secretion from the thyroid gland into blood is unknown. Humans and mice deficient in monocarboxylate transporter 8 (MCT8) have low serum thyroxine (T₄) levels that cannot be fully explained by increased deiodination. Here, we have shown that Mct8 is localized at the basolateral membrane of thyrocytes and that the serum TH concentration is reduced in Mct8-KO mice early after being taken off a treatment that almost completely depleted the thyroid gland of TH. Thyroid glands in Mct8-KO mice contained more non-thyroglobulin-associated T₄ and triiodothyronine than did those in wild-type mice, independent of deiodination. In addition, depletion of thyroidal TH content was slower during iodine deficiency. After administration of ¹²⁵I, the rate of both its secretion from the thyroid gland and its appearance in the serum as trichloroacetic acid–precipitable radioactivity was greatly reduced in Mct8-KO mice. Similarly, the secretion of T₄ induced by injection of thyrotropin was reduced in Mct8-KO in which endogenous TSH and T₄ were suppressed by administration of triiodothyronine. To our knowledge, this study is the first to demonstrate that Mct8 is involved in the secretion of TH from the thyroid gland and contributes, in part, to the low serum T₄ level observed in MCT8-deficient patients.