Comparison of the precision of two vertebral morphometry programs for the lunar EXPERT-XL imaging densitometer

Comparative precision tests of the vertebral height measurement function of the Aberdeen Vertebral Morphometry System (AVMS) software and Lunar EXPERT-XL software were undertaken using four vertebrae from the same lateral spine dual energy X-ray absorptiometry (DXA) image of the same subject (male, 67 years). Two of the vertebrae were abnormal and two were normal. Three observers inexperienced in morphometry and one experienced observer took part in the study. Repeatability was obtained from 10 sequential measurements of the posterior, middle and anterior heights at the same sitting by the same observer. Intraobserver reproducibility compared the means of one set of measurements for all vertebrae with another taken 1 week later. Interobserver reproducibility compared the means of one set of measurements for all vertebrae from an experienced and an inexperienced observer, and from two inexperienced observers. The AVMS software had significantly higher (p < 0.05) repeatability (mean coefficient of variability, CV = 3.5%) than the Lunar software (mean CV = 5%), significantly higher (p < 0.01) intraobserver reproducibility (mean CV = 4.6%) than the Lunar software (mean CV = 8.5%), and significantly higher (p < 0.05) interobserver reproducibility (mean CV = 4.7%) than the Lunar software (mean CV = 7.5%). In conclusion, the new AVMS method possessed higher precision when measuring both abnormal and normal vertebrae and when used by both experienced and inexperienced observers.     

Frequency, predictors, and appropriateness of blood transfusion after percutaneous coronary interventions

Increased awareness of the risks of blood-borne infections has recently led to profound changes in the practice of transfusion medicine. These changes include, among others, the development of guidelines by the American College of Physicians (ACP) for transfusion. Although the incidence and predictors of vascular complications of percutaneous interventions have been well defined, there are currently no data on frequency, risk factors, and appropriateness of blood transfusions. We performed a retrospective analysis of 628 consecutive percutaneous coronary revascularization procedures. Predictors of blood transfusion were identified using multivariate logistic regression analysis. Appropriateness of transfusions was determined using modified ACP guidelines. Transfusions were administered after 8.9% of interventions (56 of 628). Multivariate analysis identified age >70 years, female gender, procedure duration, coronary stenting, acute myocardial infarction, postprocedural use of heparin and intra-aortic balloon pump placement as independent predictors of blood transfusions (all p <0.05). According to the ACP guidelines, 36 of 56 patients (64%) received transfusions inappropriately. Transfusion reactions (fever) occurred in 10% of patients who received tranfusions appropriately and in 5% of patients who received tranfusions inappropriately. The estimated additional costs per procedure related to transfusions were $551 and $419, respectively. In conclusion, unnecessary transfusions were performed frequently after percutaneous coronary interventions. Application of available guidelines could reduce the number of unnecessary transfusions, thus avoiding exposure of patients to additional risks and reducing procedural costs.     

Processing and activation of pro-interleukin-16 by caspase-3

Interleukin-16, a proinflammatory cytokine produced in CD8(+) lymphocytes, is synthesized as a precursor protein (pro-IL-16). It is postulated that the C-terminal region of pro-IL-16 is cleaved, releasing bioactive IL-16. To characterize IL-16 cleavage, we transfected COS cells with a cDNA encoding a approximately 50-kDa form of pro-IL-16. Transfected COS cells released a approximately 20-kDa IL-16 cleavage product shown to consist of the 121 C-terminal residues of pro-IL-16 by immunoblotting and amino acid sequencing. Cleaved IL-16, but not pro-IL-16, exhibited lymphocyte chemoattractant activity. A C-terminal approximately 20-kDa IL-16 polypeptide was also released when pro-IL-16 was treated with concanavalin A-stimulated CD8(+) lymphocyte lysate. Cleavage occurred after an Asp, suggesting involvement of a caspase (interleukin-1beta-converting enzyme/CED-3) family protease. Using recombinant caspases and granzyme B, we determined that pro-IL-16 cleavage is mediated only by caspase-3. Relevance to pro-IL-16 processing in primary lymphocytes was supported by identifying the p20 subunit of activated caspase-3 in stimulated CD8(+) lymphocytes and by inhibition of CD8(+) lymphocyte lysate-mediated cleavage with Ac-DEVD-CHO. Pro-IL-16 is a substrate for caspase-3, and cleavage by this enzyme releases biologically active IL-16 from its inactive precursor.     

The 70-kDa heat shock cognate protein (Hsc73) gene is enhanced by ovarian hormones in the ventromedial hypothalamus

Estrogen (E) and progesterone (P) orchestrate many cellular responses involved in female reproductive physiology, including reproductive behaviors. E- and P-binding neurons important for lordosis behavior have been located within the ventromedial hypothalamus (VMH), and several hormone-responsive genes have been observed there as well. In attempts to identify additional E- and P-responsive genes in the VMH that may contribute to sexual behaviors, we used the differential display mRNA screening technique. One of the genes identified encodes the 73-kDa heat shock cognate protein (Hsc73). Quantitative in situ hybridization analysis of brains from naturally cycling female rats revealed a significant increase in Hsc73 mRNA in the VMH and arcuate nucleus of animals during proestrus compared with those at diestrus-1. To confirm that these increases were steroid hormone dependent, we compared vehicle-treated ovariectomized females with ovariectomized females treated with estradiol benzoate and P. Northern analysis and in situ hybridizations showed that the Hsc73 gene is enhanced by E and P in the pituitary and subregions of the VMH. Incidentally, by examining the primary amino acid sequence of rat, human, and chicken progesterone receptors, we noticed that putative Hsc73 binding sites are conserved across species with similar sites existing in the androgen and glucocorticoid receptors. Together these findings suggest a possible mechanism through which E could influence the activities of progesterone, androgen, and glucocorticoid receptors, by enhancing the expression of Hsc73 in cells where these proteins colocalize.     

Nicotine enantiomers and oxidative stress

Nicotine affects a variety of cellular processes ranging from induction of gene expression to secretion of hormones and modulation of enzymatic activities. The objective of this study was to characterize the toxicity of nicotine enantiomers as well as their ability to induce oxidative stress in an in vitro model using Chinese hamster ovary (CHO) cells. Colony formation assay has demonstrated that (-)-nicotine is the more toxic of the enantiomers. At 6 mM concentrations, (-)-nicotine was found to be approximately 28- and 19-fold more potent than (+)-, and (+/-)-nicotine (racemic), respectively. Results also indicated that the toxicity of (+/-)-nicotine is higher than that of (+)-nicotine. (-)-Nicotine at a 10 mM concentration substantially decreased glutathione (GSH) levels (46% decrease). In addition, a 3-fold increase in malondialdehyde (MDA) level was evident in cells after exposure to 10 mM (-)-nicotine. Increased lactate dehydrogenase (LDH) activities in the media demonstrated that cellular membrane integrity was disturbed in nicotine treated cells. In the presence of superoxide dismutase (SOD) and catalase (CAT), the LDH activities returned to control value in 24 h with all concentrations of (-)-, (+)-, and (+/-)-nicotine. The decreases in LDH activities in the presence of the radical scavenging enzymes SOD and CAT suggest that membrane damage may be due to free radical generation.     

Kinetics of CD4+ T cell repopulation of lymphoid tissues after treatment of HIV-1 infection

Potent combinations of antiretroviral drugs diminish the turnover of CD4+ T lymphocytes productively infected with HIV-1 and reduce the large pool of virions deposited in lymphoid tissue (LT). To determine to what extent suppression of viral replication and reduction in viral antigens in LT might lead correspondingly to repopulation of the immune system, we characterized CD4+ T lymphocyte populations in LT in which we previously had quantitated viral load and turnover of infected cells before and after treatment. We directly measured by quantitative image analysis changes in total CD4+ T cell counts, the CD45RA+ subset, and fractions of proliferating or apoptotic CD4+ T cells. Compared with normal controls, we documented decreased numbers of CD4+ T cells and increased proliferation and apoptosis. After treatment, proliferation returned to normal levels, and total CD4+ T and CD45RA+ cells increased. We discuss the effects of HIV-1 on this subset based on the concept that renewal mechanisms in the adult are operating at full capacity before infection and cannot meet the additional demand imposed by the loss of productively infected cells. The slow increases in the CD45RA+ CD4+ T cells are consistent with the optimistic conclusions that (i) renewal mechanisms have not been damaged irreparably even at relatively advanced stages of infection and (ii) CD4+ T cell populations can be partially restored by control of active replication without eradication of HIV-1.     

An electrophysiological study of infants' sensitivity to the sound patterns of English speech

The study explores 10- to 11-month-old infants' sensitivity to the phonological characteristics of their native language. Event-related potentials (ERPs) were obtained for tones that were superimposed on two versions of a story: an Unmodified version containing normal English function morphemes, and a Modified version in which the prosodic and segmental properties of a subset of function morphemes were changed to make them atypical. The 11-month-olds exhibited significantly lower amplitude ERPs to the tones during the Modified story than to the Unmodified story, whereas the 10-month-olds showed no differences. These results suggest that the 11-month-olds discriminated the two versions of the story based on their representations of the phonological properties of English. Further, the tone-probe ERP method can successfully be used to study the development of speech perception in the pre-linguistic infant.