The Far Ultra-Violet imager on the ICON mission

ICON Far UltraViolet (FUV) imager contributes to the ICON science objectives by providing remote sensing measurements of the daytime and nighttime atmosphere/ionosphere. During sunlit atmospheric conditions, ICON FUV images the limb altitude profile in the shortwave (SW) band at 135.6 nm and the longwave (LW) band at 157 nm perpendicular to the satellite motion to retrieve the atmospheric O/N2 ratio. In conditions of atmospheric darkness, ICON FUV measures the 135.6 nm recombination emission of O+ ions used to compute the nighttime ionospheric altitude distribution. ICON Far UltraViolet (FUV) imager is a CzernyTurner design Spectrographic Imager with two exit slits and corresponding back imager cameras that produce two independent images in separate wavelength bands on two detectors. All observations will be processed as limb altitude profiles. In addition, the ionospheric 135.6 nm data will be processed as longitude and latitude spatial maps to obtain images of ion distributions around regions of equatorial spread F. The ICON FUV optic axis is pointed 20 degrees below local horizontal and has a steering mirror that allows the field of view to be steered up to 30 degrees forward and aft, to keep the local magnetic meridian in the field of view. The detectors are micro channel plate (MCP) intensified FUV tubes with the phosphor fiber-optically coupled to Charge Coupled Devices (CCDs). The dual stack MCP-s amplify the photoelectron signals to dominate the CCD noise and the rapidly scanned frames are co-added to digitally create 12-second integrated images. Digital on-board signal processing is used to compensate for geometric distortion and satellite motion and to achieve data compression. The instrument was originally aligned in visible light by using a special grating and visible cameras. Final alignment, functional and environmental testing and calibration were performed in a large vacuum chamber with a UV source. The test and calibration program showed that ICON FUV meets its design requirements and is ready to be launched on the ICON spacecraft.

Self-expanding metallic stents for large bowel obstruction

BACKGROUND

Self-expanding metallic stents (SEMS) may relieve colonic obstruction as definitive therapy or as a bridge to elective surgery.

METHODS

This was a retrospective longitudinal cohort study of patients undergoing insertion of SEMS for large bowel obstruction at one institution. Scrutiny of the radiology department's coding system allowed identification of all patients undergoing colonic stent insertion between 2002 and 2008. Data were extracted from patient case notes and investigation reports.

RESULTS

Eighty-two patients with a median age of 75 (interquartile range (i.q.r.) 43-94) years underwent stent insertion, 71 for palliation and 11 as a bridge to surgery. Obstruction was due to malignant disease in 67 patients and had a benign cause in 15. Median survival in the palliative setting was 103 (i.q.r. 44-317) days. Complications occurred in 43 patients, of whom 22 underwent unplanned surgery. High-grade obstruction (relative risk (RR) 2·05; P = 0·055) and benign disease (RR 3·45; P < 0·001) were associated with risk of adverse events.

CONCLUSION

SEMS should not be used for large bowel obstruction with benign pathology.

Associations between risk behavior and injury and the protective roles of social environments: an analysis of 7235 Canadian school children

OBJECTIVE

The social etiology of adolescent injury remains poorly understood. The Population Health Framework suggests that the etiology of adolescent injury involves interactions between individual risk factors and the natures of adolescent environments. The purpose of this study was to apply this framework to examination of relationships between adolescent risk taking and injury, and the potential modifying effects of supportive home and school environments.

METHODS

The analysis was conducted in a representative sample of 7235 males and females (10-16 years old) from Canada. Results were based on records from the 2001/02 World Health Organization Health Behaviour in School-Aged Children Survey. Individual items and factor analytically derived scales were used to describe and then model injury outcomes, risk behaviors, perceived home, and school climates, and the relationships between these variables in a theory driven etiological analysis.

RESULTS

Adolescents with supportive home and school environments experienced lower relative odds of engagement in risk taking behavior and lower relative odds of injury. Gradients were observed between the extent of adolescent risk taking and the occurrence of injury. Interactions were not observed between risk taking behavior, perceived support in home and school climates, and injury.

CONCLUSIONS

Risk taking is common among adolescents and plays a role in the etiology of injury. Supportive social climates clearly protect adolescents from engaging in these behaviors, and also the occurrence of some forms of injury. However, once an adolescent chooses to engage in risk taking behaviour, a supportive environment may not protect them from injury.

Direct gene transfer in potato: a comparison of particle bombardment of leaf explants and PEG-mediated transformation of protoplasts

Direct gene transfer methods in potato would facilitate the transfer of multiple genes and the manipulation of metabolic pathways in this species. In this study, up to 1.8 transformation events per shot (=0.5 per bombarded leaf) and 67.2 events per million protoplasts treated were obtained with particle bombardment and PEG-mediated direct DNA uptake, respectively. Limited disassociation of both HPT and GUS genes appeared to occur during the process of integration in only 19% of transformants. A large number of transformed potato plants with transgene expression at levels comparable to Agrobacterium-mediated transformation was obtained. High levels of GUS expression were only obtained in lines derived from PEG treatment. No correlation between the number of gene insertions and gene expression levels was found, suggesting that multiple insertions may have little or no effect on transgene expression.

Patient motivations surrounding participation in phase I and phase II clinical trials of cancer chemotherapy

Successful advances in the treatment of advanced malignant diseases rely on recruitment of patients into clinical trials of novel agents. However, there is a genuine concern for the welfare of individual patients. The aim of this study was to examine motives of patients entering early clinical trials of novel cancer therapies. Questionnaire survey with both open- and close-ended questions. The patients were surveyed after they had given informed consent and before or during the first cycle of treatment. In all, 38 phase I/II trial patients participated and completed the survey. Obtaining possible health benefit was listed by 89% as being a ‘very important’ factor in their decision to participate, with only 17% giving reasons of helping future cancer patients and treatment. Other items cited as a ‘very important’ motivating factor were ‘trust in the doctor’ (66%), ‘being treated by the latest treatment available’ (66%), ‘better standard of care and closer follow-up’ (61%), and ‘closer monitoring of patients in trials’ (58%). Only 47% patients indicated that someone had explained to them about any ‘reasonable’ alternatives to the trial. In total, 71% strongly agreed that ‘surviving for as long time as possible was the most important thing (for them)’. Nearly all (97%) indicated that they knew the purpose of the trial and had enough time to consider participation in the trial (100%). In this survey, most patients entering phase I and II clinical trials felt they understood the purpose of the research and had given truly informed consent. Despite this, most patients participated in the hope of therapeutic benefit, although this is known to be a rare outcome in this patient subset. Trialists should be aware, and take account of the expectations that participants place in trial drugs.

Hereditary haemochromatosis and hepatocellular carcinoma in males: a strategy for estimating the potential for primary prevention

OBJECTIVES

Homozygosity for the C282Y mutation of the HFE gene is the main cause of iron overload in hereditary haemochromatosis. This study calculated the number of hepatocellular carcinoma cases among a cohort of white males that could be attributed to C282Y homozygosity. A better understanding of the extent of potentially preventable mortality arising from this cancer might help with decision making about the feasibility of population screening.

METHODS

We combined information from published life tables, age-specific cancer rates and DNA studies of archived liver biopsy specimens to calculate the number of cases of hepatocellular carcinoma that might occur during the lifetime of a cohort of 1,000,000 men, including a subgroup of 5000 C282Y homozygotes.

RESULTS

Hepatocellular carcinoma was estimated to occur in 2673 men in the cohort (1:374); 267 of these cases were in the subgroup of 5000 C282Y homozygotes (1:17). If these 267 cases were prevented, the remaining lifetime risk among all males would be 1:416. The relative risk for this cancer in C282Y homozygotes is 23.

CONCLUSIONS

There continues to be uncertainty about the efficacy of screening for haemochromatosis. Hepatocellular carcinoma is the most readily quantifiable serious health problem attributable to this source. Further confirmatory DNA (C282Y) studies would be helpful in larger, unbiased sets of archived biopsy specimens, as a way to confirm the present estimate. Any strategy designed to prevent attributable liver cancer is likely to prevent other serious problems from haemochromatasis as well.

The interpersonal context of romantic autonomy in adolescence

This study explored the interpersonal context of romantic autonomy in mid adolescence by examining within-relationship links with romantic intimacy and affiliation, links across relationships with mothers and friends, and individual differences due to age and gender. Two hundred and thirty adolescents in grades 9, 10 and 11 with a current romantic partner, completed self-report questionnaires assessing their relationships. The results indicated that romantic autonomy was positively linked to romantic intimacy and affiliation, although this link differed according to the duration of the romantic relationship. The results also indicated that romantic autonomy was higher among girls than boys. Finally, romantic autonomy was uniquely linked to intimacy and autonomy in both maternal and friend relationships. Overall, this study highlights the interconnection of intimacy and autonomy in romantic relationships and the interconnections across relationships.

Photoacoustic point source

We investigate the photoacoustic effect generated by heat deposition at a point in space in an inviscid fluid. Delta-function and long Gaussian optical pulses are used as sources in the wave equation for the displacement potential to determine the fluid motion. The linear sound-generation mechanism gives bipolar photoacoustic waves, whereas the nonlinear mechanism produces asymmetric tripolar waves. The salient features of the photoacoustic point source are that rapid heat deposition and nonlinear thermal expansion dominate the production of ultrasound.

HLA and interleukin 1 gene polymorphisms in primary biliary cirrhosis: associations with disease progression and disease susceptibility

BACKGROUND AND AIMS

Twin and family studies suggest that there is a genetic component to primary biliary cirrhosis (PBC) but the genetic associations which have been described are weak with marked variations between centres. PBC is heterogeneous and genetic associations with disease progression may be obscured when the PBC population is analysed only as a whole and not subdivided.

METHODS

We have investigated two candidate gene loci in 164 well characterised patients, 88 (54%) of whom had advanced disease.

RESULTS

There was an increased frequency of the HLA DRB1*0801-DQA1*0401-DQB1*0402 haplotype in patients who had progressed to late stage disease (23% v 2% of controls; p=0000044; odds ratio (OR) 15.5, 95% confidence interval (CI) 3.52-68.4) but not in those with early stage disease (4% v 2%). Patients had a higher frequency of the IL-1B*1,1 genotype and lower frequencies of the IL-1B*1,2 and *2,2 genotypes (p=0.00078; OR 2.37, 95% CI 1.38-4.06), and higher frequency of the IL-1RN*1,1 genotype and lower frequency of the IL-1RN*1,2 genotype (p=0.0011; OR 2.28, 95% CI 1.34-3.89). The difference in the IL-1B*1,1 genotype distribution was most marked in patients with early stage disease (77% v 43% of controls; p=0.000003; OR 4.8, 95% CI 2.31-10) but the IL-1RN genotype distribution was similar in patients with early and late stage disease.

CONCLUSIONS

These data indicate a complex relationship between immunoregulatory genes and PBC. While the IL-1 genes are markers of both disease susceptibility and progression, HLA genes appear to be principally associated with disease progression.

Managing chronic hepatitis C acquired through intravenous drug use

We retrospectively reviewed the provision and uptake of hospital services for 253 current and ex-intravenous drug users with hepatitis C virus (HCV). Overall, 237 attended at least one clinic (mean age 32 years, 70% male, 43% on maintenance methadone); 81% had evidence of active viral replication and 137 agreed to a liver biopsy to assess disease severity. Of these 137, 24% had mild chronic hepatitis with a low risk of progression to cirrhosis, but 9% had cirrhosis (mean age 40 years, mean time since initial intravenous drug use 15.8 years). Only 50 of the 100 patients in whom antiviral therapy was indicated, commenced treatment; 18 (36%) have had a sustained virological response. The natural history or response to treatment of chronic HCV in those who acquire it through intravenous drug use is not different to that previously reported for post-transfusion HCV. However, a substantial proportion default from follow-up or decline further intervention. As intravenous drug use is now the main risk factor for acquisition of HCV, these data have implications for future delivery of care aimed at limiting the morbidity of chronic HCV, and limiting the spread of hepatitis C virus infection amongst intravenous drug users.

Dating experiences of bullies in early adolescence

In this study, 196 young adolescents who reported that they bullied their peers were identified out of a sample of 1,758 students in Grades 5 through 8. After selecting from the total sample a group of nonbullying youth who were matched on gender, school, and grade, a comparison was made of the groups' dating experiences, quality of friend and boyfriend or girlfriend relationships, and acts of physical and social aggression. The results indicated that bullies started dating earlier and engaged in more advanced dyadic dating than comparison adolescents. Bullies were highly relationship oriented, yet their views of their friends and boyfriends or girlfriends were less positive and less equitable than the comparison adolescents. Finally, bullies were more likely to report physical and social aggression with their boyfriends or girlfriends. Although the bullies reported more advanced pubertal development, this factor did not fully account for their dating precocity and negative romantic relationships. The results confirmed our hypotheses that adolescents whose peer relationships are characterized by bullying are at risk in their development of healthy romantic relationships.

Sex steroids, the insulin-like growth factor regulatory system, and aging: implications for the management of older postmenopausal women

Aging is associated with profound changes in the growth hormone/insulin-like growth factor (IGF) regulatory system. These include reductions in growth hormone, IGF-I, IGFBP3, and IGFBP-5 and an increase in IGFBP-4. These changes, coupled with rather marked declines in sex steroid production from both the ovary and adrenals may combine to have very deleterious effects on several organ systems in the postmenopausal woman. In particular, the prevalence of two very common diseases, osteoporosis and coronary artery disease, increase dramatically after the cessation of gonadal steroid production. The complex interrelationship between the IGF regulatory system and estrogens/androgens in the postmenopausal period may provide important clues as to the pathophysiology of both these disorders. In this paper, we begin to define the role of IGF-I (and its constituent IGF binding proteins) in skeletal and vascular tissue. Recent experimental data show the effects of estrogen on circulating and tissue IGFs in older individuals. Finally, estrogen replacement therapy affects the IGF regulatory system in postmenopausal women. Although conclusions from early studies remain somewhat preliminary, it is likely that the IGF regulatory system will be a prime target for future studies into the pathogenesis of several age and sex hormone related degenerative disorders.

Development of thermally formed glass optics for astronomical hard X-ray telescopes

The next major observational advance in hard X-ray/soft gamma-ray astrophysics will come with the implementation of telescopes capable of focusing 10-200 keV radiation. Focusing allows high signal-to-noise imaging and spectroscopic observations of many sources in this band for the first time. The recent development of depth-graded multilayer coatings has made the design of telescopes for this bandpass practical, however the ability to manufacture inexpensive substrates with appropriate surface quality and figure to achieve sub-arcminute performance has remained an elusive goal. In this paper, we report on new, thermally-formed glass micro-sheet optics capable of meeting the requirements of the next-generation of astronomical hard X-ray telescopes.

Bacteriologic efficacies of oral azithromycin and oral cefaclor in treatment of acute otitis media in infants and young children

A prospective, open-label, randomized study was conducted in order to determine the bacteriologic efficacies of cefaclor and azithromycin in acute otitis media (AOM). Tympanocentesis was performed on entry into the study and 3 to 4 days after initiation of treatment. Bacteriologic failure after 3 to 4 days of treatment with both drugs occurred in a high proportion of culture-positive patients, especially in those in whom AOM was caused by Haemophilus influenzae (16 of 33 [53%] of those treated with azithromycin and 13 of 34 [52%] of those treated with cefaclor). Although a clear correlation of the persistence of the pathogen with increased MICs of the respective drugs could be demonstrated for Streptococcus pneumoniae, no such correlation was found for H. influenzae. It is proposed that susceptibility breakpoints for H. influenzae should be considerably lower than the current ones for both cefaclor and azithromycin for AOM caused by H. influenzae.

Peer involvement in bullying: insights and challenges for intervention

The purpose of this research was to examine the peer processes that occur during bullying episodes on the school playground. These processes were examined from a social learning perspective, allowing us to consider the effects of various types of reinforcement among bullies, victims, and peers. Fifty-three segments of video tape were examined. Each segment contained a peer group (two or more peers) that viewed bullying on the school playground. Peers were coded for actively joining or passively reinforcing the bully, and for actively intervening on behalf of the victim. On average, four peers viewed the schoolyard bullying, with a range from two to 14 peers. Averaged across all episodes, peers spent 54% of their time reinforcing bullies by passively watching, 21% of their time actively modelling bullies, and 25% of their time intervening on behalf of victims. Older boys (grades 4-6) were more likely to actively join with the bully than were younger boys (grades 1-3) and older girls. Both younger and older girls were more likely to intervene on behalf of victims than were older boys. The results were interpreted as confirming peers' central roles in the processes that unfold during playground bullying episodes. We discuss the results in terms of the challenges posed to peer-led interventions. Peers' anti-bullying initiatives must be reinforced by simultaneous whole-school interventions.

Predictors of outcome in drug treatment of adolescent inpatients

Little is known about for whom treatment is most effective and how to match adolescent clients to substance-abuse treatment. 280 adolescents treated in a multifaceted program participated. Of these, 128 did not complete treatment prior to termination of the 2-mo. inpatient phase. They were significantly different from clients who completed treatment measures of alienation, social maladaptation, aggression, and lower occupational status of the father. Of those who completed inpatient treatment and remained in the study at 1-mo. postdischarge (n = 69) two groups were formed, those who improved and those who either remained the same or worsened in terms of substance abuse. For those who improved factors which differentiated them were identification with middle-class values, tendency to be older, initial difficulty identifying emotions, and depressive symptoms at intake. Clients who did not change or worsened were distinguished by more social anxiety, depressive symptoms, and troubling thoughts at intake. These results suggest that individual characteristics may identify cases who are more likely to benefit from treatment.

Somatic embryogenesis and plant regeneration from stem explants of Moricandia arvensis

Efficient and reproducible plant regeneration has been established from stem internode explants of Moricandia arvensis, a crucifer of special interest due to its C₃-C₄ intermediate photosynthetic activity. Somatic embryogenesis was induced in one-third of explants cultured on Murashige and Skoog based medium containing 9 mM 2,4-dichlorophenoxyacetic acid. High frequencies of plant regeneration (>90%) resulted when somatic embryos were germinated on medium lacking growth regulators. Regenerated plants were diploid, fertile and morphologically similar to seed-derived plants of M. arvensis. This is the first report of somatic embryogenesis in M. arvensis. This plant regeneration system should facilitate gene identification and localisation studies of C₃-C₄ physiology by insertional mutagenesis, a prerequisite for the isolation and transfer of genes involved in C₃-C₄ metabolism from Moricandia to cultivated brassicas.

Further characterization of the plasma lipoprotein(a) distribution

The plasma lipoprotein (a) [Lp(a)] distribution in caucasians is heavily skewed to the right, with evidence of bimodality. As there is a well-described inverse relationship between apolipoprotein(a) [apo(a)] size and Lp(a) concentration, it is likely that the presence of multiple apo(a) isoforms of differing frequency has a significant impact on the final distribution of Lp(a) concentrations. We have previously described an immunoblot method for examining the relationship between apolipoprotein(a) [apo(a)] size and lipoprotein(a) [Lp(a)] mass among samples heterozygous for apo(a) size, thus eliminating confounding by null or undetected apo(a) isoforms. In the present study, this method has been applied to examine the plasma Lp(a) distribution, independent of the effects of apo(a) isoform size and frequency. Seventy subjects heterozygous for apo(a) size were studied. To take into account the inverse relationship (P < 0.001) between apo(a) isoform size and Lp(a) concentration, Lp(a) data associated with each apo(a) isoform were normalized as multiples of the median Lp(a) concentration for that isoform. These apo(a) isoform-independent Lp(a) data demonstrated a strikingly multimodal distribution, with five major peaks. The relative frequencies of Lp(a) peaks 1-5 were 17.1%, 15.0%, 35.7%, 23.6%, and 8.6%, and associated median Lp(a) concentrations were 1.0, 6.2, 15.0, 21.8, and 39.6 mg/dL, respectively. Multivariate analysis demonstrated that apo(a) isoform size accounted for 23% and isoform-independent Lp(a) peaks for 59.5% of the variation in Lp(a) concentration. Further investigation of the characteristics of the apo(a) isoform-independent Lp(a) distribution is warranted.

CD45 isoform expression on human haemopoietic cells at different stages of development

Alternate splicing and glycosylation produce multiple CD45 isoforms which are selectively expressed on the surface of cells of the haemopoietic system. The expression of CD45RA, CD45RB and CD45RO on CD34+ and CD34- haemopoietic cells from umbilical cord blood, bone marrow and fetal liver were studied by flow cytometry. CD34+ subpopulations defined by CD45 isoform expression were sorted from bone marrow and tested in long-term culture assays. By combining results of functional studies with phenotypic data and previously published information, the following pattern of CD45 isoform expression on early haemopoietic cells was established. The most primitive CD34+ cells are CD45RO+ CD45RB+ and express low or undetectable levels of CD45RA. Upon erythroid differentiation, CD34+ cells remain CD45RO+ CD45RB+, whereas commitment into the myeloid and lymphoid lineages coincides with down-regulation of CD45RO and up-regulation of CD45RA. As a result, the majority of CD34+ cells can be divided into two mutually exclusive populations of cells which express either CD45RO or CD45RA. This notion was confirmed in this study by three-colour immunofluorescence. The alternative expression of various CD45 isoforms on functionally distinct haemopoietic cells suggests an important role for these molecules in the proliferation and differentiation of haemopoietic cells.

Trimethoprim-sulfamethoxazole prophylaxis in granulocytopenic patients with acute leukemia: evaluation of serum antibiotic levels in a randomized, double-blind, placebo-controlled Department of Veterans Affairs Cooperative Study

Despite widespread use of trimethoprim-sulfamethoxazole (TMP-SMZ) for prophylaxis in neutropenic patients, questions remain regarding its efficacy, toxicity, the risk of selection of resistant isolates, and the relation of its activity to selective decolonization vs. the attainment of direct inhibitory levels within blood and tissues. We evaluated the effect of TMP-SMZ (160/800 mg orally every 12 hours) in 42 adult granulocytopenic patients (< 100 absolute neutrophils/mm3, mean duration 13.3 days) undergoing chemotherapy for acute leukemia at 11 participating Veterans Administration Medical Centers in a randomized, double-blind, placebo-controlled trial. No significant differences in survival, frequency of bacteremia, overall infections, use of systemic antimicrobial therapy, or adverse effects, including myelosuppression, were observed between patients receiving TMP-SMZ vs. those receiving placebo. All patients acquired trimethoprim-resistant organisms. Concentrations of trimethoprim in serum were significantly lower before febrile episodes than when patients were afebrile. These results suggest that the purported activity of TMP-SMZ may be related to the serum concentration achieved. Moreover, the results highlight the need for additional study of the value of antibiotic prophylaxis in neutropenic patients.

Risk assessment in immunotoxicology. II. Relationships between immune and host resistance tests

We have reported on the design and content of a screening battery using a "tier" approach for detecting potential immunotoxic compounds in mice (Luster et al., Fundam. Appl. Toxicol., 10, 2-19, 1988). The data base generated from these studies, which consists of over 50 selected compounds, has been collected and analyzed in an attempt to improve future testing strategies and provide information to aid in developing future quantitative risk assessment for immunotoxicity. In a recent study it was shown that as few as two or three immune parameters were needed to predict immunotoxicants in mice (Luster et al., Fundam. Appl. Toxicol., 18, 200-210, 1992). In particular, enumeration of lymphocyte populations and quantitation of the T-dependent antibody response were particularly beneficial. Furthermore, commonly employed apical measures (e.g., leukocyte counts, lymphoid organ weights) were fairly insensitive. The present analyses focus on the use of this data base to develop statistical models that examine the qualitative and quantitative relationship(s) between the immune function and host resistance tests. The conclusion derived from these analyses are: (1) A good correlation exists between changes in the immune tests and altered host resistance in that there were no instances where host resistance was altered without affecting an immune test(s). However, in some instances immune changes occurred without corresponding changes in host resistance. (2) No single immune test could be identified which was fully predictive for altered host resistance, although most assays were relatively good indicators (i.e., > 70%). Several others, such as proliferative response to lipopolysaccharide and leukocyte counts, were found to be relatively poor indicators for host resistance changes. (3) The ability to resist infectious agent challenge is dependent upon the degrees of immunosuppression and the quantity of infectious agent administered. (4) Logistic and standard regression modeling using one extensive chemical data set from the immunosuppressive agent, cyclophosphamide, indicated that most immune function-host resistance relationships followed linear rather than linear-quadratic (threshold-like) models. For most of the relationships this could not be confirmed using a large chemical data set and, thus, a more mechanistically based approach for modeling will need to be developed. (5) Using this limited data set, methods were developed for modeling the precise quantitative relationships between changes in selected immune tests and host resistance tests.

Expression of Thy-1 on human hematopoietic progenitor cells

Expression of Thy-1 on hematopoietic cells from human fetal liver (FL), cord blood (CB), and bone marrow (BM) was studied with a novel anti-Thy-1 antibody, 5E10. Specificity of 5E10 for human Thy-1 was demonstrated by immunoprecipitation of a 25-35-kD molecule, and the sequence of a cDNA that was cloned by immunoselection of COS cells transfected with a cDNA library derived from a 5E10+ cell line. Two- and three-color immunofluorescence staining experiments revealed that the Thy-1 expression is restricted to, an average, 1-4% of FL, CB, and BM cells, and binding to these cell types is essentially restricted to a very small subset of lymphoid cells and approximately 25% of CD34+ cells. Thy-1+ CD34+ cells were further characterized as CD38lo/CD45RO+/CD45RA-/CD71lo/c-kit(lo) and rhodamine 123dull. When CD34+ cells were sorted on the basis of Thy-1 expression, the majority of clonogenic cells were recovered in the CD34+Thy-1- fraction, whereas the majority of cells capable of producing myeloid colonies after 5-8 wk of long-term culture (long-term culture initiating cells) were recovered in the Thy-1+CD34+ fraction. In addition to CD34+ cells, Thy-1 was found to be expressed on a variable, very small number (< 1%) of CD34- mononuclear cells in BM, CB, and peripheral blood that were further characterized as CD3+ CD4+ lymphocytes. The restricted expression of Thy-1 on primitive hematopoietic cells is in agreement with a previous report (Baum et al., 1992. Proc. Natl. Acad. Sci. USA. 89:2804) in which Thy-1 expression was used to enrich for primitive hematopoietic cells from fetal tissue. Compared with those previous studies, we found Thy-1 expression on a larger proportion of CD34+ cells (25% in our study vs. 5% in Baum et al.) and furthermore performed studies on Thy-1 expression on CD34+ cells from CB, FL, and BM in relation to markers that are known to be differentially expressed on hematopoietic cells. Taken together our results indicate that Thy-1-specific antibody 5E10 is an attractive tool for further studies on the biology and purification of human stem cells.

A novel integrin specificity exemplified by binding of the alpha v beta 5 integrin to the basic domain of the HIV Tat protein and vitronectin

Several studies have addressed the interaction of the HIV Tat protein with the cell surface. Our analysis of the cell attachment-promoting activity of Tat and peptides derived from it revealed that the basic domain of Tat, not the arg-gly-asp (RGD) sequence, is required for cell attachment to Tat. Affinity chromatography with Tat peptides and immunoprecipitation with various anti-integrin antibodies suggest that the vitronectin-binding integrin, alpha v beta 5, is the cell surface protein that binds to the basic domain of Tat. The Tat basic domain contains the sequence RKKRRQRRR. A related sequence, KKQRFRHRNRKG, present in the heparin-binding domain of an alpha v beta 5 ligand, vitronectin, also bound alpha v beta 5 in affinity chromatography and, in combination with an RGD peptide, was an inhibitor of cell attachment to vitronectin. The alpha v beta 5 interaction with these peptides was not solely due to high content of basic amino acids in the ligand sequences; alpha v beta 5 did not bind substantially to peptides consisting entirely of arginine or lysine, whereas a beta 1 integrin did bind to these peptides. The interaction of alpha v beta 5 with Tat is atypical for integrins in that the binding to Tat is divalent cation independent, whereas the binding of the same integrin to an RGD-containing peptide or to vitronectin requires divalent cations. These data define an auxiliary integrin binding specificity for basic amino acid sequences. These basic domain binding sites may function synergistically with the binding sites that recognize RGD or equivalent sequences.

Relevance of animal models for clinical treatment

The use of animal models has become an integral part of the evaluation of drugs for antimicrobial chemotherapy. Animal models can be used to define the penetration of antimicrobial agents at foci of infections, the time course of in vivo antimicrobial therapy, dose-response relationships, and the influence of therapy on the pathophysiologic consequences of infection. Animal models have been useful in the delineation of many of the basic principles currently used in clinical practice and in the selection of new agents and new therapeutic approaches for clinical trials in humans. In spite of the many positive aspects of animal models, several problems, such as altered pharmacokinetics in animals, can preclude direct application of results to clinical practice. Studies in animal models cannot replace the need for human clinical trials.

Pharmacodynamics of antimicrobial agents as a basis for determining dosage regimens

Pharmacodynamic parameters, such as the rate of bactericidal activity with increasing drug concentrations, post-antibiotic effect, sub-MIC effects, post-antibiotic leukocyte enhancement and first-exposure effect, more accurately describe the time course of antimicrobial activity than the MIC and MBC. Aminoglycosides and quinolones exhibit concentration-dependent killing and induce prolonged post-antibiotic effects. The amount of drug rather than the dosing frequency determines the efficacy of these drugs. However, high peak levels can reduce the emergence of resistance, and once-daily dosing of aminoglycosides can also reduce nephrotoxicity and ototoxicity. On the other hand, beta-lactam antibiotics show time-dependent killing and produce prolonged post-antibiotic effects only with staphylococci. The frequency of drug administration is an important determinant of outcome for these drugs, as the duration of time serum levels exceed the MIC is the major determinant of efficacy.

Randomized controlled trial of prophylactic rifampin for peritoneal dialysis-related infections

Staphylococcal infections are a major cause of catheter infections and peritonitis in peritoneal dialysis patients. Since catheter-related infections are associated with nasal carriage of Staphylococcus aureus in this population, we studied the effect of intermittent rifampin, an antibiotic known to decrease S aureus nasal carriage, on catheter-related infections and peritonitis. We randomly assigned 64 patients to receive either rifampin 300 mg twice daily for 5 days every 3 months or no treatment. The rifampin-treated patients had a significant delay in time to first catheter-related infection (P less than 0.015) and significantly fewer catheter-related infections overall (P less than 0.001). The catheter-related infection rate in rifampin-treated patients was .26 per patient-year versus .93 per patient-year in untreated patients. Multivariate analysis defined baseline colonization of nares or catheter exit-site and prior renal transplant as risk factors for catheter-related infections. There was no significant difference in peritonitis rates between groups, although the trend was for a delayed time to first episodes and fewer episodes in rifampin-treated patients. Adverse effects necessitated withdrawal of rifampin in four patients. We conclude that intermittent rifampin administration is effective in decreasing catheter-related infections in a peritoneal dialysis population.

Blinded comparison of cefuroxime to cefaclor for lower respiratory tract infections

Cefuroxime axetil was compared with cefaclor for the therapy for lower respiratory tract infections. Sixty-one patients were randomized to receive the following drug dosages: (1) cefuroxime axetil, 250 mg orally every 12 hours (21 patients); (2) cefuroxime axetil, 500 mg orally every 12 hours (21 patients); and (3) cefaclor, 500 mg orally every eight hours (19 patients). Of these 61 patients, 80% were male, with a mean age of 59.5 years; 56% had acute pneumonia, and the remainder had an acute bronchitis. Causative pathogens included typical respiratory tract pathogens. Overall, 23 of 27 patients with bronchitis were clinically cured at the end of therapy. Thirty-one of 34 pneumonias were clinically cured or improved at the end of therapy; the three pneumonia treatment failures occurred in the lower dose cefuroxime (n = 2) and cefaclor (n = 1) treatment groups. Overall, bacteriologic cure occurred in 86% of patients treated with 500 mg of cefuroxime axetil compared with 60% of cefaclor-treated patients. Adverse clinical effects were uncommon. From this study, it was concluded that cefuroxime given every 12 hours is at least as clinically efficacious as cefaclor; it is a new oral cephalosporin with pharmacologic and bacterial spectrum advantages over many older agents.

Pharmacokinetic and experimental data on beta-lactam antibiotics in the treatment of patients

The in vitro and animal model studies on optimal dosage of the newer beta-lactams are summarized and put into historical perspective. They provide a rationale for dosage schedules that continuously maintain inhibitory serum and tissue concentrations throughout the dosage interval. In vitro studies on the post-antibiotic effect (PAE) with beta-lactams revealed only short time periods of post-antibiotic growth suppression with gram-positive cocci and no post-antibiotic effect with gram-negative bacilli. A similar lack of persistent growth suppression was observed with beta-lactams in a neutropenic mouse thigh infection model for both gram-positive and gram-negative bacteria. In the same animal model, dosing regimens of beta-lactams which continuously provided serum concentrations above the MIC were more efficacious than those that did not. The newer third-generation cephalosporins have prolonged half-lives and can maintain serum levels above the MIC for most pathogens, even when dosed at widely spaced intervals.

Functional orthopedics: the "four pieces" and Class II treatment

The authors describe a new functional appliance called the Chateau four pieces, which is designed for the orthopedic treatment of Class II problems during growth. The versatility of the use of the four pieces simultaneously or separately, enables the practitioner to control treatment in three dimensions. The indications and the prescription are discussed, and the results are shown.

Prostatic mucinous carcinoma

Four criteria are proposed for establishing the pathologic diagnosis of prostatic mucinous carcinoma. Twenty-one reported cases of this rare tumor are reviewed, and a new case is presented. The clinical and pathologic features of 16 authentic features of 16 authentic cases are analyzed.

Cetocycline, tetracycline analog: in vitro studies of antimicrobial activity, serum binding, lipid solubility, and uptake by bacteria

Cetocycline (formerly chelocardin or cetotetrine) is structurally related to the tetracyclines. It was found to be more active than tetracycline against many clinical isolates of aerobic gram-negative bacilli, but is less active against staphylococci, and has no activity against Pseudomonas. It is bactericidal against susceptible enteric gram-negative bacteria at concentrations two to four times higher than the minimal inhibiting concentrations. The drug is highly lipid soluble; more than 80% is bound to serum, and it is more avidly taken up by susceptible bacteria than tetracycline. A direct correlation between drug uptake and susceptibility of bacteria was not noted, except with a strain of Proteus vulgaris.

Diterpenoids. XXVII. The selenium dehydrogenation of manool

The structures of 14 products derived from the selenium dehydrogenation of manool have been determined. The formation and disappearance of these compounds in the dehydrogenation mixture is discussed.