Coupling of kinesin steps to ATP hydrolysis

A key goal in the study of the function of ATP-driven motor enzymes is to quantify the movement produced from consumption of one ATP molecule. Discrete displacements of the processive motor kinesin along a microtubule have been reported as 5 and/or 8 nm. However, analysis of nanometre-scale movements is hindered by superimposed brownian motion. Moreover, because kinesin is processive and turns over stochastically, some observed displacements must arise from summation of smaller movements that are too closely spaced in time to be resolved. To address both of these problems, we used light microscopy instrumentation with low positional drift (< 39 pms[-1]) to observe single molecules of a kinesin derivative moving slowly (approximately 2.5nm s[-1]) at very low (150nM) ATP concentration, so that ATP-induced displacements were widely spaced in time. This allowed increased time-averaging to suppress brownian noise (without application of external force), permitting objective measurement of the distribution of all observed displacement sizes. The distribution was analysed with a statistics-based method which explicitly takes into account the occurrence of unresolved movements, and determines both the underlying step size and the coupling of steps to ATP hydrolytic events. Our data support a fundamental enzymatic cycle for kinesin in which hydrolysis of a single ATP molecule is coupled to a step distance of the microtubule protofilament lattice spacing of 8.12 nm. Step distances other than 8nm are excluded, as is the coupling of each step to two or more consecutive ATP hydrolysis reactions with similar rates, or the coupling of two 8-nm steps to a single hydrolysis. The measured ratio of ATP consumption rate to stepping rate is invariant over a wide range of ATP concentration, suggesting that the 1 ATP to 8nm coupling inferred from behaviour at low ATP can be generalized to high ATP.

Evaluation of the Hexaplex assay for detection of respiratory viruses in children

The Hexaplex assay (Prodesse, Inc., Milwaukee, Wis.) is a multiplex reverse transcriptase (RT)-PCR assay for the detection of parainfluenza virus types 1, 2, and 3, respiratory syncytial virus (RSV) types A and B, and influenza virus types A and B. We evaluated the Hexaplex assay in comparison with conventional viral cell cultures and rapid enzyme immunoassays (EIAs) for RSV (Directigen; Becton Dickinson Inc., Cockeysville, Md.) and influenza A virus (Abbott Test Pack; Abbott Laboratories, Abbott Park, Ill.) for the detection of respiratory viruses from pediatric respiratory specimens obtained from children seen at Children's Hospital of Wisconsin from December 1997 through May 1998. A total of 363 respiratory specimens were evaluated. The tissue culture prevalence of parainfluenza virus during this period of time was low (1.1%). The sensitivity, specificity, and positive and negative predictive value of Hexaplex compared to tissue culture for the detection of parainfluenza virus were 100, 95.8, 19.0, and 100%, respectively. Only one specimen was determined to contain influenza B virus by Hexaplex; it was tissue culture negative. A specimen was considered to contain RSV or influenza A virus when it was either culture positive or culture negative but Hexaplex and EIA positive. Prior to the analysis of discrepant results, the sensitivity, specificity, and positive and negative predictive value for the detection of RSV were 91.2, 100, 100, and 98.0%, respectively, for tissue culture; 84.5, 100, 100, and 96.6% for EIA; and 98.5, 91.5, 72.8, and 99.6% for Hexaplex, respectively. The sensitivity, specificity, and positive and negative predictive value for the detection of influenza A virus prior to the analysis of discrepant results were 100, 100, 100, and 100%, respectively, for culture, 78.0, 100, 100, and 89.4% for EIA, respectively, and 95.1, 94.1, 67.2, and 99.3% for Hexaplex, respectively. Culture- and/or EIA-negative, Hexaplex-positive specimens were analyzed by a second RT-PCR assay which used primers specific for a different genomic region than that used in the Hexaplex assay. After analysis of these discrepant results, the sensitivity, specificity, and positive and negative predictive value for the detection of RSV were 74.3, 100, 100, and 93.5%, respectively, for tissue culture; 70.3, 100, 100, and 92.5% for EIA; and 98.6, 97.4, 91.2, and 99.6% for Hexaplex. The sensitivity, specificity, and positive and negative predictive value for the detection of influenza A virus were 83.3, 100, 100, and 97.4%, respectively, for tissue culture; 69.4, 100, 100, and 83.3% for EIA; and 95.8, 98.7, 92.0, and 99.3% for Hexaplex. Hexaplex is a rapid, sensitive, and specific method for the detection of the seven most common respiratory viruses in children.

Berberine suppresses colon cancer cell proliferation by inhibiting the SCAP/SREBP-1 signaling pathway-mediated lipogenesis

Lipid metabolism is a significant section of energy homeostasis, and it affects the development of various cancers. Previous studies have revealed that berberine has strong anticancer and blood lipid-lowering effects. Here, we further investigated the effects of berberine on cell proliferation and lipogenesis in colon cancer cells and the relationship between the two effects. We found that berberine inhibited cell proliferation by inducing G0/G1 phase cell cycle arrest in colon cancer cells. Moreover, the expressions of key lipogenic enzymes were down-regulated by berberine and led to the suppressed lipid synthesis, which was linked to cell proliferation via Wnt/β-catenin pathway. Importantly, berberine inhibited sterol regulatory element-binding protein-1 (SREBP-1) activation and SREBP cleavage-activating protein (SCAP) expression, resulting in the downregulation of these lipogenic enzymes. Knockdown of SCAP by shRNA could abolish the effect of berberine on SREBP-1 activation. Besides the inhibitory effects in vitro, berberine suppressed the growth and lipogenesis of colon cancer xenograft in a SCAP-dependent manner as well. Together, our results suggest that berberine may serve as a candidate against tumor growth of colon cancer partially through targeting SCAP/SREBP-1 pathway driving lipogenesis.

Social support networks and medical service use among HIV-positive injection drug users: implications to intervention

The study used network analysis to identify forms and sources of social support associated with a medical services use among a medically underserved population living with HIV/AIDS. Participants were African American former or current injection drug users (n=295; 34% female, 45% current drug users and 17% AIDS diagnosed). Outcomes were access to the same medical provider, use of outpatient services and emergency room (ER) use with or without subsequent hospitalization. Controlling for AIDS diagnosis, insurance, current drug use and gender, access to the same medical care provider was associated with more females in one's support network and more network sources of emotional support, financial support and instrumental assistance. Adjusting for confounders, outpatient service use was associated with more female support network members and more sources of emotional support. Controlling for participants' drug use and insurance, sub-optimal emergency department use was associated with greater number of active drug users in one's support network. Contrary to other study findings, having a supportive sex partner was associated with lower access to medical care, and kin support was not associated with medical service use. Results indicate that specific sources and forms of social support had differential influences on the sample's utilization of medical services. The findings suggest that promoting HIV-positive African American injection drug users' support network functioning may help improve HIV medical services utilization among this medically underserved population.

Genistein protects against DSS-induced colitis by inhibiting NLRP3 inflammasome via TGR5-cAMP signaling

NLRP3 inflammasome has been reported to be associated with inflammatory bowel disease including colitis due to its potential ability to induce IL-1β secretion. Emerging studies have demonstrated that Genistein, a major isoflavone, has potential anti-inflammatory effects in murine model colitis. However, its anti-inflammatory mechanism remains unclear. The effects of Genistein in dextran sulfate sodium (DSS)-induced murine colitis via targeting NLRP3 inflammasome was investigated in this study. Also, the mechanisms of protective action of Genistein in DSS-induced colitis may relate to TGR5 signaling. Genistein treatment not only remarkably attenuated loss of body weight and shortening of colon length but also significantly reduced inflammatory cells infiltration and pro-inflammatory mediator production in serum and colon. Moreover, Genistein treatment down-regulated production of caspase-1 and IL-1β and increased intracellular cAMP level, which were similar to the treatment for INT-777, a semi-synthetic TGR5 agonist, in phorbol myristate acetate (PMA)-differentiated monocytic THP-1 cells and U937 cells. These protective effects of Genistein might be attributed by ubiquination of NLRP3 which was induced due to interaction of cAMP with NLRP3. Furthermore, the effects of Genistein on NLRP3 inflammasome disappeared in TGR5-silenced U937 cells. In conclusion, our study unveils that Genistein was able to inhibit NLRP3 inflammasome via TGR5-cAMP signaling in macrophages. It therefore might be a potential effective drug for inflammatory bowel diseases.

The relationship between social network characteristics and exchanging sex for drugs or money among drug users in Baltimore, MD, USA

The current study examined social network and drug use factors associated with buying and selling sex among a sample of opiate and cocaine users in Baltimore, Maryland. A sample of 702 drug users who were sexually active were administered a social network and risk behaviour inventory. Compared to 25% of men, only 1.7% of women reported a history of giving money or drugs to get sex during the past 90 days. Conversely, more women (21.2%) than men (4.7%) sold sex for money or drugs. Those who sold sex were more likely to be low frequency crack smokers, were more likely to drink alcohol at least once a day, had a higher average number of crack-only smokers in their network, and had a smaller number of kin in their network. Men who exchanged money or drugs for sex tended to be low frequency crack smokers and reported having more crack-only smokers and injectors and fewer kin in their networks. The results suggest that network composition may be a risk factor for exchanging sex, particularly with respect to crack users, while kin may be a protective factor. These associations may be either a cause or consequence of exchanging sex.

SKOV3 ovarian carcinoma cells have functional estrogen receptor but are growth-resistant to estrogen and antiestrogens

Estrogen receptor positive ovarian cancer is often refractile to antiestrogen therapy. Here we describe the SKOV3 human ovarian carcinoma cell line as an in vitro model for estrogen and antiestrogen resistant ovarian cancer. While SKOV3 cells expressed estrogen receptor (ER) mRNA and protein at a similar level as the estrogen responsive T47D breast carcinoma cell line, their growth was not responsive to estradiol (E2) and was not inhibited by the antiestrogens OH-tamoxifen and ICI 164,384. The ER in SKOV3 cells was normal with respect to apparent Kd for binding with E2, E2 regulation of a transiently transfected ERE driven reporter gene, and E2 stimulation of expression of the early growth response genes c-myc and c-fos. However, the SKOV3 cells exhibited no expression of the progesterone receptor gene (PR) even after addition of E2, and the protein products of the estrogen responsive genes HER-2/neu and cathepsin D were expressed at constitutive levels that were not regulated by E2. Therefore, estrogen resistance in these cells may be a result of constitutive expression and loss of E2 regulation of selected growth regulatory gene products rather than a defect in estrogen activation of ER as a transcriptional regulator.

Estrogen action in human ovarian cancer

Evidence is accumulating for a facilitative role for estrogen in ovarian cancer. Although response to antiestrogen therapy has been poor, there is a distinct subset of patients that respond. Strategies for treatment of ovarian cancer would be improved by identification of patients likely to respond to hormonal therapy. Cell culture models that are responsive or resistant to estrogen and antiestrogen may be of value in finding markers that predict responsiveness to hormonal therapy. Several model cell lines have been generated that express ER and proliferate in response to estrogen in vitro. Further studies are needed to better characterize the response of these ER positive cells lines to estrogen in vivo in mouse xenograft models. Expression of many of the same genes are regulated by estrogen in breast and in ovarian cancer cell lines. One exception may be the HER-2/neu oncogene product, which is down-regulated by estrogen in responsive breast carcinoma cells but not in two ovarian carcinoma cell lines. Initial analyses of several estrogen responsive and one resistant cell model suggests the potential value of progesterone receptor presence and low levels of HER-2/neu expression for predicting responsiveness to hormonal therapy. Additional cell models need to be investigated to determine the frequency with which these markers are associated with antiestrogen resistance.

Developmentally expressed Ca(2+)-sensitive adenylyl cyclase activity is disrupted in the brains of type I adenylyl cyclase mutant mice

The type I Ca(2+)-sensitive adenylyl cyclase has been implicated in several forms of synaptic plasticity in vertebrates. Mutant mice in which this enzyme was inactivated by targeted mutagenesis show deficient spatial memory and altered long term potentiation (Wu, Z. L., Thomas, S. A., Villacres, E. C., Xia, Z., Simmons, M. L., Chavkin, C., Palmiter, R. D., and Storm, D. R. (1995) Proc. Natl Acad Sci. U. S. A. 92, 220-224). Long term potentiation in the CA1 region of the rat hippocampus develops during the first 2 weeks after birth and reaches maximal expression at postnatal day 15 with a gradual decline at later stages of development. Here we report that Ca(2+)-stimulated adenylyl cyclase activity in rat hippocampus, cerebellum, and cortex increases significantly between postnatal days 1-16. This increase appears to be due to enhanced expression of type I adenylyl cyclase rather than type VIII adenylyl cyclase, the other adenylyl cyclase that is directly stimulated by Ca2+ and calmodulin. Type I adenylyl cyclase mRNA in the hippocampus increased 7-fold during this developmental period. The developmental expression of Ca(2+)-stimulated adenylyl cyclase activity in mouse brain was attenuated in mutant mice lacking type I adenylyl cyclase. Changes in expression of the type I adenylyl cyclase during the period of long term potentiation development are consistent with the hypothesis that this enzyme is important for neuroplasticity and spatial memory in vertebrates.

Synthesis and characterization of pyridine-based polyamido-polyester optically active macrocycles and enantiomeric recognition for D- and L-amino acid methyl ester hydrochloride

Five new chiral macrocycles, 3a-e, have been prepared by the acylation cyclization of chiral diamine dihydrobromide intermediates 2a-c with 2,6-pyridinedicarbonyl dichloride in highly diluted solution at room temperature. The chiral diesters 1a-c needed for the preparation of the macrocycles were obtained from condensation of corresponding N-(Z)-L-amino acids and 2,6-bishydroxymethyl pyridine in the presence of DCC and DMAP. The enantiomeric recognition of chiral macrocycles 3a-e for D- and L-amino acid methyl ester hydrochlorides has been characterized by fluorescence spectra, which indicate that some of them exhibited significant chiral recognition for the enantiomers of D- and L-amino acid methyl ester hydrochlorides. The stoichiometry and binding constants of 3a-L-Am(2) and 3c-L-Am(2) complexes have been determined. An X-ray analysis of the chiral macrocycle 3b show that the chiral ligand is rather rigid and strained.

Eosinophil differentiation in the bone marrow is promoted by protein tyrosine phosphatase SHP2

SHP2 participates in multiple signaling events by mediating T-cell development and function, and regulates cytokine-dependent granulopoiesis. To explore whether and how SHP2 can regulate bone-marrow eosinophil differentiation, we investigate the contribution of SHP2 in the bone-marrow eosinophil development in allergic mice. Blockade of SHP2 function by SHP2 inhibitor PHPS-1 or conditional shp2 knockdown by adenovirus-inhibited bone-marrow-derived eosinophil differentiation in vitro, with no detectable effects on the apoptosis of eosinophils. Furthermore, SHP2 induced eosinophil differentiation via regulation of the extracellular signal-regulated kinase pathway. Myeloid shp2 conditional knockout mice (LysM^creshp2^flox/flox) failed to induce eosinophilia as well as airway hyper-responsiveness. The SHP2 inhibitor PHPS-1 also alleviated eosinophilic airway inflammation and airway hyper-responsiveness, accompanied by significantly reduced levels of systemic eosinophils and eosinophil lineage-committed progenitors in allergic mice. We demonstrate that inhibition of eosinophil development is SHP2-dependent and SHP2 is sufficient to promote eosinophil formation in vivo. Our data reveal SHP2 as a critical regulator of eosinophil differentiation, and inhibition of SHP2 specifically in myeloid cells alleviates allergic airway inflammation.

Determination of edible bird's nest and its products by gas chromatography

A specific gas chromatographic (GC) detection method for edible bird's nest (EBN) based on identifying the composition of the oligosaccharide chain combined with glycoprotein in EBN is developed. Five monoses (D-mannitose, D-galactose, N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, and N-acetyl neuraminate) that constitute the oligosaccharide chain are detected using GC and GC-mass spectrometry techniques; their characteristic GC spectrum can reliably be regarded as EBN's fingerprint. The peak-area ratios in GC spectrum of those five monoses are found to be fixed; therefore, the GC technique developed in this work can conveniently be used to determine various raw EBNs and their products both qualitatively and quantitatively, distinguishing between fake and genuine EBN rapidly.

A pump-free and high-throughput microfluidic chip for highly sensitive SERS assay of gastric cancer-related circulating tumor DNA via a cascade signal amplification strategy

Circulating tumour DNA (ctDNA) has emerged as an ideal biomarker for the early diagnosis and prognosis of gastric cancer (GC). In this work, a pump-free, high-throughput microfluidic chip coupled with catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) as the signal cascade amplification strategy (CHA–HCR) was developed for surface-enhanced Raman scattering (SERS) assays of PIK3CA E542K and TP53 (two GC-related ctDNAs). The chip consisted of six parallel functional units, enabling the simultaneous analysis of multiple samples. The pump-free design and hydrophilic treatment with polyethylene glycol (PEG) realized the automatic flow of reaction solutions in microchannels, eliminating the dependence on external heavy-duty pumps and significantly improving portability. In the reaction region of the chip, products generated by target-triggered CHA initiated the HCR, forming long nicked double-stranded DNA (dsDNA) on the Au nanobowl (AuNB) array surface, to which numerous SERS probes (Raman reporters and hairpin DNA-modified Cu₂O octahedra) were attached. This CHA–HCR strategy generated numerous active “hot spots” around the Cu₂O octahedra and AuNB surface, significantly enhancing the SERS signal intensity. Using this chip, an ultralow limit of detection (LOD) for PIK3CA E542K (1.26 aM) and TP53 (2.04 aM) was achieved, and the whole process was completed within 13 min. Finally, a tumour-bearing mouse model was established, and ctDNA levels in mouse serum at different stages were determined. To verify the experimental accuracy, the gold-standard qRT–PCR assay was utilized, and the results showed a high degree of consistency. Thus, this rapid, sensitive and cost-effective SERS microfluidic chip has potential as an ideal detection platform for ctDNA monitoring.

Chronic steroid-eluting lead performance: a comparison of atrial and ventricular pacing

It is generally believed that atrial pacing leads have higher stimulation thresholds and long-term complication rates than ventricular leads, and this is one of the factors limiting the use of dual chamber pacing. A study was undertaken to compare atrial and ventricular bipolar tined steroid-eluting leads in two designs: the Medtronic CapSure SP and the Telectronics Encor Dec. There were 123 pairs of leads: 81 CapSure SP and 42 Encor Dec. Bipolar atrial and ventricular stimulation thresholds, electrograms, and pacing impedance were measured using the Telectronics META DDDR pulse generator immediately postimplantation, and at 1, 3, and 6 months for all leads and at 12, 18, and 24 months for the CapSure SP. The only major lead complication was a 2% atrial lead dislodgment rate. All leads demonstrated low stimulation thresholds, with the CapSure SP leads having lower values than comparable Encor Dec leads. All leads had a mean range of 0.53-0.89 V at all testing periods with P < 0.05 for atrial leads only. There were no differences in electrogram size between manufacturers and no instances of atrial and ventricular undersensing. Pacing impedance was about 100 omega higher for the Encor Dec leads (P < 0.05, atrial leads only), suggesting that these leads will result in lower pacing energy losses provided the pulse generators are at identical settings. More than 90% of patients could be paced chronically in the atrium and ventricle at 2.5 V, but for chronic 1.6-V pacing, the CapSure SP leads were superior. In conclusion, atrial and ventricular steroid-eluting leads of both manufacturers gave excellent stimulation threshold results allowing low energy dual chamber pacing.

Atrial pacing leads: the clinical contribution of steroid elution

Although the original atrial pacing leads were passive fixation and J shaped for right atrial appendage placement, the subsequent development of the active fixation screw-in lead found favor because of a perceived low incidence of lead dislodgment and a wider selection of atrial pacing sites. A bipolar atrial lead study was undertaken to compare the long-term atrial implant data in 215 patients. Study leads comprised one passive fixation, steroid-eluting lead (Medtronic CapSure SP, 119 patients) and three nonsteroid-eluting leads; two active fixation (Medtronic BISPING model 4058, 30 patients; and Telectronics ACCUFIX model 330-801, 44 patients) and one passive fixation (Telectronics ENCOR model 330-854, 22 patients). Bipolar atrial voltage stimulation thresholds and electrograms were measured using the Telectronics META DDDR immediately postimplantation, and at 1-, 3-, 6-, 12-, and 18-month follow-up. There were 135 males and the mean age 68 years. The incidence of lead dislodgment was 4% for active fixation and 2% for passive fixation. All nonsteroid leads showed a typical rise in stimulation threshold with the highest being the ACCUFIX followed by the BISPING and ENCOR. The steroid-eluting CapSure SP, however, demonstrated a flat response with 98% of leads at 18 months having a value < or = 1.3 volts allowing voltage programming to 2.5 volts (2:1 safety ratio). Telemeted electrograms showed no differences for all leads at all visits. For low voltage atrial pacing with a low incidence of dislodgment and satisfactory atrial sensing, the steroid-eluting passive fixation lead is superior to all nonsteroid-eluting leads.

Comparison of two series of non-invasive instruments used for the skin physiological properties measurements: the DermaLab® from Cortex Technology vs. the series of detectors from Courage & Khazaka

BACKGROUND/PURPOSE

The detectors from Courage & Khazaka and DermaLab^® from Cortex Technology were two series of the most commonly used non-invasive instruments for the skin physiological properties measurements. The aim of this study is to reveal the differences and correlations in measuring skin color, hydration, transepidermal water loss (TEWL), sebum and elasticity on the forearm or faces between two commercially available series of instruments.

METHODS

30 subjects were enrolled to be measured by the two series of instruments. The measurements by each series were performed on the left/right side of the body randomly. The hydration, sebum, elasticity and TEWL measurements were performed on different sites.

RESULTS

Positive correlations were found in the values of skin color, hydration, TEWL, sebum and visco-elasticity detected by the two series. The values related to skin firmness measured by the two instruments were statistically negative correlated. Contrary to the results in measuring the skin color, the detectors from Courage & Khazaka presented lower values of variation in measuring skin hydration and TEWL than those from DermaLab^® .

CONCLUSION

The two series have significant correlations.The differences of the two series can be due either to differences in the design of the probe or left/right part of the body.

Serum concentrations of resistin and adiponectin and their relationship to insulin resistance in subjects with impaired glucose tolerance

OBJECTIVES

This study measured the serum concentrations of resistin and adiponectin in Chinese subjects with impaired glucose tolerance (IGT) and investigated their association with insulin resistance, metabolic parameters and circulating inflammatory markers.

METHODS

A total of 124 subjects participated in the study (44 with IGT and 80 with normal glucose tolerance [NGT]). Fasting serum concentrations of lipids, glucose, insulin and adipocytokines (resistin, adiponectin, leptin, tumour necrosis factor-α [TNF-α], interleukin-6 and C-reactive protein) were measured.

RESULTS

Serum resistin concentrations were similar in the IGT and NGT groups but were significantly higher in overweight/ obese IGT subjects than in those of normal weight. Serum adiponectin concentrations were significantly lower in the IGT group than in the NGT group. In the IGT group, resistin was positively correlated with age, body mass index and TNF-α, and adiponectin was correlated positively with high-density lipoprotein cholesterol and negatively with TNF-α and waist/hip ratio.

CONCLUSIONS

Circulating resistin is unlikely to be a major mediator of glucose tolerance in humans but it may have an inflammatory role in IGT. The data support the theory that circulating adiponectin has an anti-inflammatory and anti-insulin resistance function.

Distant lymph nodes serve as pools of Th1 cells induced by neonatal BCG vaccination for the prevention of asthma in mice

BACKGROUND

Neonatal Bacillus Calmette-Guérin (BCG) vaccination induces vigorous T-helper type 1 (Th1) responses and inhibits allergy-related airway dysfunction, but the exact mechanisms remain unclear. The objective of this study was to address where the Th1 cells induced by neonatal BCG vaccination are generated and stored, and how they are recruited into the inflamed airway for the prevention of allergen-induced airway inflammation.

METHODS

We vaccinated neonatal C57BL/6 mice with BCG in a mouse model of asthma and analyzed the expression and function of Th1 cells in vivo and in vitro.

RESULTS

BCG vaccination-induced Th1 cells in the local inguinal lymph nodes (ILN) migrated into the lungs upon inhaled ovalbumin (OVA) challenge in OVA-sensitized mice. These CD4(+) T cells in the ILN exhibited potentials of activation, proliferation and cytokine secretion and expressed high levels of CXCR3. Adoptive transfer of CD4(+) T cells from BCG-treated ILN significantly decreased allergic airway responses. In addition, the protective effect of BCG vaccination against allergic airway inflammation was lost upon the excision of the ILN.

CONCLUSIONS

These data demonstrate that ILN serves as a 'weapon' pool of Th1 cells following BCG vaccination, and these cells are ready for the migration into the inflamed lungs upon the allergen challenge, thereby inhibiting allergen-induced airway disorder.

Individual and environmental factors related to quitting heroin injection

This study examines the relationship between individual-level and the certain neighborhood characteristics with drug use cessation among a sample of long-term inner-city heroin injectors in Baltimore, Maryland. The data were derived from baseline and first follow-up visits of SHIELD, a larger HIV prevention intervention study targeting members of the drug-using community. The survey instrument was interviewer-administered and ascertained sociodemographics, drug use history, and sexual and drug risk behaviors. The data were collected between August 1997 and March 1999. The current study was limited to participants with a median age of 41 years old. 27.5% (n=53) reported quitting drug use at follow-up. Compared with those who quit, participants who continued (n=147) were close to five times as likely to buy drugs in the neighborhoods in which they lived, 80% less likely to have used drugs in a shooting gallery in the past 6 months, and close to five times more likely to have used drugs in outside places. Controlling for other factors, enrollment in drug user treatment programs or attending self-help groups were not significantly associated with drug use cessation. This study points to the importance of examining specific environmental factors in relation to quitting drug use. Research is needed to further articulate the types and characteristics of physical environments that are related to and could be intervened in promoting sustainable drug cessation.