Strategies for efficient production of heterologous proteins in Escherichia coli

In recent years, the number of recombinant proteins used for therapeutic applications has increased dramatically. Production of these proteins has a remarkable demand in the market. Escherichia coli offers a means for the rapid and economical production of recombinant proteins. These advantages, coupled with a wealth of biochemical and genetic knowledge, have enabled the production of such economically therapeutic proteins such as insulin and bovine growth hormone. These demands have driven the development of a variety of strategies for achieving high-level expression of protein, particularly involving several aspects such as expression vectors design, gene dosage, promoter strength (transcriptional regulation), mRNA stability, translation initiation and termination (translational regulation), host design considerations, codon usage, and fermentation factors available for manipulating the expression conditions, which are the major challenges is obtaining the high yield of protein at low cost.

Molecular understanding of aminoglycoside action and resistance

Aminoglycosides are potent bactericidal antibiotics targeting the bacterial ribosome, where they bind to the A-site and disrupt protein synthesis. They are particularly active against aerobic, Gram-negative bacteria and act synergistically against certain Gram-positive organisms. Aminoglycosides are used in the treatment of severe infections of the abdomen and urinary tract, bacteremia, and endocarditis. They are also used for prophylaxis, especially against endocarditis. Bacterial resistance to aminoglycosides continues to escalate and is widely recognized as a serious health threat. This might be the reason for the interest in understanding the mechanisms of resistance. It is now clear that the resistance occurs by different mechanisms such as prevention of drug entry, active extrusion of drugs, alteration of the drug target (mutational modification of 16S rRNA and mutational modification of ribosomal proteins), and enzymatic inactivation through the expression of enzymes, which covalently modify these antibiotics. Enzymatic inactivation is normally due to acetyltransferases, nucleotidyltransferases, and phosphotransferases. In this review, we focus on the recent concept of molecular understanding of aminoglycoside action and resistance.

Prospective randomized clinical trial to evaluate the optimal dose of 131 I for remnant ablation in patients with differentiated thyroid carcinoma

BACKGROUND

Radioiodine has been used for more than a half-century to ablate thyroid remnants following thyroid surgery, but a single optimal dose has not been established. We designed a prospective randomized trial to determine the optimal dose of 131 I for remnant ablation.

METHODS

Using a simple randomization technique, 149 patients with remnant thyroid were incorporated into 4 treatment groups. Twenty-seven of these patients were administered 25 to 34 millicurie (mCi) of 131 I (30 +/- 1.5), 54 received 35 to 64 mCi (50.6 +/- 5.4), 38 received 65 to 119 mCi (88.6 +/- 14) and 30 patients received 120 to 200 mCi (155 +/- 28.7). Six months to 1 year after treatment, all subjects were reassessed after withdrawing L-thyroxine for 4 to 6 weeks. A successful ablation was defined as the absence of thyroid bed activity in 5 mCi 131 I neck scan at 48 hours along with 2 adjunctive criteria which were the neck uptake of <0.2% of the administered activity and the thyroglobulin (Tg) value of <10 ng/mL.

RESULTS

Applying the above criteria, we observed complete ablation of 17 of 27 thyroid gland remnants (63%) in the 30 mCi group, 42 of 54 (77.8%) in the 50 mCi group, 28 of 38 (73.7%) in the 90 mCi group and 23 of 30 (76.7%) in the 155 mCi group. When the radiation-absorbed dose was calculated, a 30 mCi dose delivered approximately 20,000 centigray (cGy), a 50 mCi dose about 30,000 cGy, a 90 mCi dose about 50,000 cGy, and a 155 mCi dose about 130,000 cGy.

CONCLUSIONS

Increasing the empirical 131 I initial dose to more than 50 mCi results in plateauing of the dose-response curve and thus, conventional high dose remnant ablation needs critical evaluation. Based on dosimetry results, one should aim to deliver about 30,000 cGy to the thyroid remnant, as higher doses do not appear to yield a higher ablation rate.

Anethum graveolens: An Indian traditional medicinal herb and spice

Anethum graveolens L. (dill) has been used in ayurvedic medicines since ancient times and it is a popular herb widely used as a spice and also yields essential oil. It is an aromatic and annual herb of apiaceae family. The Ayurvedic uses of dill seeds are carminative, stomachic and diuretic. There are various volatile components of dill seeds and herb; carvone being the predominant odorant of dill seed and α-phellandrene, limonene, dill ether, myristicin are the most important odorants of dill herb. Other compounds isolated from seeds are coumarins, flavonoids, phenolic acids and steroids. The main purpose of this review is to understand the significance of Anethum graveolens in ayurvedic medicines and non-medicinal purposes and emphasis can also be given to the enhancement of secondary metabolites of this medicinal plant.

Scaffolds for tissue engineering of cardiac valves

Tissue engineered heart valves offer a promising alternative for the replacement of diseased heart valves avoiding the limitations faced with currently available bioprosthetic and mechanical heart valves. In the paradigm of tissue engineering, a three-dimensional platform - the so-called scaffold - is essential for cell proliferation, growth and differentiation, as well as the ultimate generation of a functional tissue. A foundation for success in heart valve tissue engineering is a recapitulation of the complex design and diverse mechanical properties of a native valve. This article reviews technological details of the scaffolds that have been applied to date in heart valve tissue engineering research.

Prodrug design to improve pharmacokinetic and drug delivery properties: challenges to the discovery scientists

The prodrug design is a versatile, powerful method that can be applied to a wide range of parent drug molecules, administration routes, and formulations. Clinically, the majority of prodrugs are used with the aim of enhancing drug permeation by increasing lipophilicity, or by improving aqueous solubility. Prodrug design may improve the bioavailability of parent molecule, and thus can be integrated into the iterative process of lead optimization, rather than employing it as a post-hoc approach. The purpose of this review is to provide an update of advances and progress in the knowledge of current strategic approaches of prodrug design, along with their real-world utility in drug discovery and development. The review covers the type of prodrugs and functional groups that are amenable to prodrug design. Various prodrug approaches for improving oral drug delivery are discussed, with numerous examples of marketed prodrugs, including improved aqueous solubility, improved lipophilicity, transporter-mediated absorption, and prodrug design to achieve site-specific delivery. Tools employed for prodrug screening, and specific challenges in prodrug research and development are also elaborated. This article is intended to encourage discovery scientists to be creative and consider a rationally designed prodrug approach during the lead optimization phase of drug discovery programs, when the structure activity relationship (SAR) for the drug target is incompatible with pharmacokinetic or biopharmaceutical objectives.

Genetic adaptation for seed dormancy in Avena fatua

Genetic variability affecting duration of primary dormancy is demonstrated in natural populations of wild oats. Marked differences were found among local populations in germination behavior. The evidence suggests that these differences result in part from genetic adaptation to agronomic practices.

Comparative assessment of genetic diversity in wild and primitive cultivated barley in a center of diversity

Wild barley (Hordeum spontaneum K.) and indigenous primitive varieties of cultivated barley (Hordeum vulgare L.), collected from 43 locations in four eastern Mediterranean countries, Jordan, Syria, Turkey and Greece, were electrophoretically assayed for genetic diversity at 16 isozyme loci. Contrary to a common impression, cultivated barley populations were found to maintain a level of diversity similar to that in its wild progenitor species. Apportionment of overall diversity in the region showed that in cultivated barley within-populations diversity was of higher magnitude than the between-populations component. Neighboring populations of wild and cultivated barleys showed high degree of genetic identity. Groups of 3 or 4 isozyme loci were analyzed to detect associations among loci. Multilocus associations of varying order were detected for all three groups chosen for the analysis. Some of the association terms differed between the two species in the region. Although there was no clear evidence for decrease in diversity attributable to the domestication of barley in the region, there was an indication of different multilocus organizations in the two closely related species.

CHLOROPLAST AND MITOCHONDRIAL DNA VARIATION IN HORDEUM VULGARE AND HORDEUM SPONTANEUM

A survey of restriction fragment polymorphism in Hordeum vulgare and Hordeum spontaneum was made using 17 and 16 hexanucleotide restriction endonucleases on chloroplast (cp) and mitochondrial (mt) DNA, respectively. The plant accessions originated from various places throughout the Fertile Cresent and Mediterranean. The types of changes in cpDNA consisted of nucleotide substitutions and insertions and deletions on the order of 100 base pairs. In contrast, mtDNA has most likely undergone larger insertions and deletions of up to 20 kilobase pairs in addition to rearrangements. Grouping of mtDNA fragment data showed that in some cases geographical affinities existed between the two species, whereas in others there were no clear affinities. Nucleotide diversity estimates derived from the restriction fragment data were used in a number of comparisons of variability. Comparisons of overall mtDNA variability (nucleotide diversity = 9.68 × 10-4) with cpDNA variability (nucleotide diversity = 6.38 × 10-4) indicated that the former are somewhat more variable. Furthermore, there was no indication that the wild H. spontaneum (cpDNA diversity = 5.57 × 10-4; mtDNA diversity = 6.04 × 10-4) was more variable than the land races of H. vulgare (cpDNA diversity = 5.88 × 10-4; mtDNA diversity = 9.79 × 10-4). In fact, on the basis of mtDNA diversity, H. vulgarewas the more variable species. Comparison of organelle nucleotide diversity estimates with an estimate of nuclear nucleotide diversity derived from existing isozyme data provided evidence that both organelle genomes are evolving at a slower rate than the nuclear genome.

Robust Heartbeat Detection From Multimodal Data via CNN-Based Generalizable Information Fusion

OBJECTIVE

Heartbeat detection remains central to cardiac disease diagnosis and management, and is traditionally performed based on electrocardiogram (ECG). To improve robustness and accuracy of detection, especially, in certain critical-care scenarios, the use of additional physiological signals such as arterial blood pressure (BP) has recently been suggested. Therefore, estimation of heartbeat location requires information fusion from multiple signals. However, reported efforts in this direction often obtain multimodal estimates somewhat indirectly, by voting among separately obtained signal-specific intermediate estimates. In contrast, we propose to directly fuse information from multiple signals without requiring intermediate estimates, and thence estimate heartbeat location in a robust manner.

METHOD

We propose as a heartbeat detector, a convolutional neural network (CNN) that learns fused features from multiple physiological signals. This method eliminates the need for hand-picked signal-specific features and ad hoc fusion schemes. Furthermore, being data-driven, the same algorithm learns suitable features from arbitrary set of signals.

RESULTS

Using ECG and BP signals of PhysioNet 2014 Challenge database, we obtained a score of 94%. Furthermore, using two ECG channels of MIT-BIH arrhythmia database, we scored 99.92%. Both those scores compare favorably with previously reported database-specific results. Also, our detector achieved high accuracy in a variety of clinical conditions.

CONCLUSION

The proposed CNN-based information fusion (CIF) algorithm is generalizable, robust and efficient in detecting heartbeat location from multiple signals.

SIGNIFICANCE

In medical signal monitoring systems, our technique would accurately estimate heartbeat locations even when only a subset of channels are reliable.

HIV type 1 subtypes circulating in eastern and northeastern regions of India

Genetic subtyping has been a powerful tool in tracking the global spread of HIV. To determine the HIV-1 subtypes circulating in eastern and northeastern regions of India blood samples were collected from female sex workers in Calcutta and intravenous drug users (IDUs) in Manipur. Fifty-four samples from Calcutta and 25 samples from Manipur were analyzed for HIV-1 subtyping by heteroduplex mobility assay (HMA). Twenty-six samples from these regions were sequenced. HMA and sequencing of the samples from these regions revealed subtype C as the major subtype, circulating within both eastern and northeastern regions. In Manipur, subtype ThaiB was also detected as the second major subtype. Some of the IDUs from Manipur were found to be dual infected with subtype C and ThaiB.

Dormancy studies in seed of Avena fatua. 11. Heritability for seed dormancy

The heritability of the dormancy of primary seeds in four populations of wild oats was estimated by the parent–progeny regression method and found to be approximately 50% under field conditions.

Zinc supplementation as adjunct therapy in children with measles accompanied by pneumonia: a double-blind, randomized controlled trial

BACKGROUND

Zinc deficiency, common in developing countries, is associated with decreased immunocompetence. Zinc supplementation benefits children with acute and persistent diarrhea and prevents pneumonia. Most deaths from vaccine-preventable diseases are from measles and whooping cough; pneumonia is the most common complication of measles and often the proximate cause of related deaths.

OBJECTIVE

We evaluated the effect of zinc supplementation on episodes of illness in children with measles accompanied by pneumonia.

DESIGN

In a double-blind, randomized controlled trial, children aged 9 mo-15 y who were admitted to the Infectious Diseases Hospital in Calcutta with clinically severe measles accompanied by pneumonia and who had been ill for </= 7 d were randomly assigned to receive zinc (20 mg, in elemental form as acetate, twice daily for 6 d) or a placebo. All patients received standard treatment with antibiotics and an initial 100 000-IU dose of vitamin A (as palmitate) by mouth.

RESULTS

Time-to-event analysis using the Cox proportional hazards model (42 in the zinc group and 43 in the placebo group) showed that the time needed for the resolution of fever and tachypnea, the return of appetite, and the achievement of a "much improved" or "cured" status was not different between the 2 groups. A high proportion of children had low serum retinol and zinc concentrations. Improvement in serum zinc and retinol concentrations after 6 d of treatment was not different between the 2 groups.

CONCLUSION

Children with severe measles accompanied by pneumonia treated with antibiotics and vitamin A did not show any additional benefit from also receiving a zinc supplement.

Comparison of apoptosis and mortality measurements in peripheral blood mononuclear cells (PBMCs) using multiple methods

Death through apoptosis is the main process by which aged cells that have lost their function are eliminated. Apoptotic cells are usually detected microscopically by changes in their morphology. However, determination of early apoptotic events is important for in vitro (and ex vivo) studies. The main objective of the present study is to find the most sensitive method for apoptosis detection in human peripheral blood mononuclear cells (PBMCs) by comparing six different methods following five different means of immunological stimulation at 3 and 5 days. Each of six apoptosis quantification methods, except the trypan blue exclusion test, is a combination of two stains, one for the specific detection of apoptotic cells and the other for the unspecific detection of dead cells. Values for apoptosis and mortality were compared with a reference method. The choice of apoptosis detection method is more important following 3 days of stimulation than after 5 days of stimulation (P=2x10(-6) versus P=1x10(-2)). In contrast, we find mortality measurements following the different means of stimulation highly significant at both 3 and 5 days (F2.28=7.9, P=1.4x10(-6) at 3 days and F2.28=8.5, P=4.5x10(-7) at 5 days). Variation as a result of the combination of specific PBMC stimulation and the method used to detect apoptosis is reduced considerably with time (F1.58+3.7, P+3x10(-7) at 3 days to F=1.58=0.97, P=0.5 at 5 days). Based on Tukey's test, YO-PRO-1 is the most sensitive stain for apoptosis and, when combined with 7-AAD, provides an accurate measure of apoptosis and mortality. In conclusion, we propose YO-PRO-1/7-AAD as a new combination and low-cost alternative for the sensitive detection of early apoptosis.

RNA interference: potential therapeutic targets

One of the most exciting findings in recent years has been the discovery of RNA interference (RNAi). RNAi methodologies hold the promise to selectively inhibit gene expression in mammals. RNAi is an innate cellular process activated when a double-stranded RNA (dsRNA) molecule of greater than 19 duplex nucleotides enters the cell, causing the degradation of not only the invading dsRNA molecule, but also single-stranded (ssRNAs) RNAs of identical sequences, including endogenous mRNAs. The use of RNAi for genetic-based therapies has been widely studied, especially in viral infections, cancers, and inherited genetic disorders. As such, RNAi technology is a potentially useful method to develop highly specific dsRNA-based gene-silencing therapeutics.

Wettability of nano-epoxies to UHMWPE fibers

Ultra high molecular weight polyethylene (UHMWPE) fibers have a unique combination of outstanding mechanical, physical, and chemical properties. However, as reinforcements for manufacturing high performance composite materials, UHMWPE fibers have poor wettability with most polymers. As a result, the interfacial bonding strength between the fibers and polymer matrices is very low. Recently, developing so-called nano-matrices containing reactive graphitic nanofibers (r-GNFs) has been proposed to promote the wetting of such matrices to certain types of fiber reinforcements. In this work, the wettability of UHMWPE fibers with different epoxy matrices including a nano-epoxy, and a pure epoxy was investigated. Systematic experimental work was conducted to determine the viscosity of the epoxies, the contact angle between the epoxies and the fibers. Also obtained are the surface energy of the fibers and the epoxies. The experimental results show that the wettability of the UHMWPE fibers with the nano-epoxy is much better than that of the UHMWPE fibers with the pure epoxy.

Low HIV and high STD among commercial sex workers in a brothel in Bangladesh: scope for prevention of larger epidemic

The present study documents the first systematic assessment of a brothel in Bangladesh in terms of sexually transmitted disease (STD) and human immunodeficiency virus (HIV). A cross sectional study was undertaken on brothel-based commercial sex workers (CSWs) selected systematic random sampling to assess the prevalence of STDs and HIV among CSWs in a brothel setting. Two hundred and ninety-six CSWs were selected from a brothel with a population of 593 women. Following informed consent, endocervical and blood samples were obtained for the diagnosis of genital chlamydia, gonorrhoea, HIV and syphilis respectively. In addition, another 170 consecutive blood samples were collected from the total CSW population for HIV tests. All blood samples for HIV testing were made anonymous by removing patient identifiers before testing. Endocervical specimens were tested by polymerase chain reaction (PCR) for the diagnosis of genital chlamydia and gonorrhoea. Syphilis and HIV infections were diagnosed by serology. One hundred and sixty-nine (57.1%) of the women were Treponema pallidum haemagglutination (TPHA)-positive, 20 (6.8%) of the women were Venereal Disease Research Laboratory (VDRL)-positive at a greater than 1:8 dilution. Eighty-two (28%) of the women were found to be infected either by gonorrhoea or chlamydia. No HIV antibody was found in any of the 466 blood samples. A high prevalence of STDs and low prevalence of HIV in the CSWs in Bangladesh suggest potential for the rapid spread of HIV once it is introduced in this high-risk population. The opportunity to control STD and HIV infection in this population should not be missed, in order to prevent a large epidemic in the future.

Dynamic changes in CD4+ CD25+(high) T cell apoptosis after the diagnosis of type 1 diabetes

Because type 1 diabetes (T1D) is a chronic, autoimmune, T cell-mediated disease, interventions affecting T cells are expected to modulate the immune cascade and lead to disease remission. We propose that increased CD4(+) CD25(+high) T cell apoptosis, a trait we discovered in recent-onset T1D subjects, reflects T1D partial remission within the first 6 months after diagnosis. Apoptosis of forkhead box P3 (FoxP3)(+) CD4(+) CD25(+high) T cells, in addition to total daily doses of insulin (TDD), blood glucose, HbA1c and age, were measured in 45 subjects with T1D at various times after diagnosis. Sixteen healthy control subjects were also recruited to the study. Higher CD4(+) CD25(+high) T cell apoptosis levels were detected within the first 6 months of diagnosis (odds ratio = 1.39, P = 0.009), after adjustment for age, TDD and HbA1c. A proportional hazards model confirmed that the decline of apoptosis after diagnosis of T1D was related significantly to survival time (hazards ratio = 1.08, P = 0.014), with TDD and age also contributing to survival. During this time there was an inverse relationship between CD4(+) CD25(+high) T cell apoptosis with TDD (r = -0.39, P = 0.008). The CD4(+) CD25(+high) T cell apoptosis levels decline significantly after the first 6 months from diagnosis of T1D and may help in the close monitoring of autoimmunity. In parallel, there is an increase in TDD during this time. We also propose that CD4(+) CD25(+high) T cell apoptosis assay can be used to gauge the efficacy of the several immune tolerance induction protocols, now under way.

Patterns of changes of dormant genotypes in Avena fatua populations under different agricultural conditions

Experimental evidence is provided to support earlier suggestions that summer-fallowing of cropland enhances the relative abundance of dormant wild oats at the expense of nondormant ones. Two heterogeneous populations of wild oats, Avena fatua L., were synthesized, each composed of a different set of true-breeding dormant and nondormant lines in equal initial frequencies. Subsequent generations of these mixed-stand populations were grown without conscious selection under two cultivation conditions: (i) propagation in every growing season (continuous cropping) and (ii) a 2-year rotation consisting of a year of propagation followed by a year of summer-fallowing. These experimental populations responded differently to the two cultivation practices. The relative frequency of dormant lines increased substantially in both populations propagated under the summer-fallow regime, compared with the continuous-cropping regime. Implications of this finding for weed control are discussed.

Synthesis of Some New Isoxazoline Derivatives of Chalconised Indoline 2-one as a Potential Analgesic, Antibacterial and Anthelmimtic Agents

A series of novel 1[5”-(2”’-substituted phenyl)-4”,5”’-dihydro isoxazole-3”-yl]-3-[(4 substituted phenyl)imino]1-3-dihydro-2H-indole-2-one were synthesized from different substituted chalconised indole-2,3-dione was prepared from the different chalconised Isatin. The structures of the compounds were elucidated by elemental and spectral (IR, ¹H NMR, and MS) analysis. The synthesized compounds were screened for their analgesic activity by the acetic acid induced Writhing method and in vitro antimicrobial activity against the Gram-positive bacteria—Staphylococcus aureus and the Gram-negative bacteria—Pseudomonas auroginosa, Pseudomonas mirabilis, and E. coli by the cup plate agar diffusion method. Compounds 6a₁, 6a₃, 6b₃, and 6b₂ were found to be active against bacteria. The compounds 6a₁, 6b₃, and 6a₃ show a significant analgesic activity. Synthesized compounds also screened for anthelmintic activity against Pheretima posthuma. Compounds 6a₁, 6b₁, and 6b₃ show significant anthelmintic activity.

Molecular targets for design of novel inhibitors to circumvent aminoglycoside resistance

Aminoglycosides are a class of clinically important antibiotics used in the treatment of infections caused by Gram-positive and Gram-negative organisms. They are bactericidal, targeting the bacterial ribosome, where they bind to the A-site and disrupt protein synthesis. Antibiotic resistance is a growing problem for all classes of anti-infective agents. One of the first groups of antibiotics to encounter the challenge of resistance was the aminoglycoside -aminocyclitol family. Initially, the resistance that emerged in organisms such as Mycobacterium tuberculosis was restricted to modification of the antibiotic targets, which we now know to be the bacterial ribosomal rRNA and proteins. As new aminoglycosides came to the clinic, however, the prevalence of chemical modification mechanisms of resistance became dominant. Enzymatic modification of aminoglycosides through kinases (O-phosphotransferases, APHs), O-adenyltransferases (ANTs) and N-acetyltransferases (AACs) has emerged in virtually all clinically relevant bacteria of both Gram-positive and Gram-negative origin. Although their clinical use has been extensive, their toxicity and the prevalence of resistance in clinical strains have prompted the pharmaceutical industry to look for alternatives. Whereas the search for novel targets for antibiotics from the genomic information is ongoing, no antibacterial agent based on these efforts has so far entered clinical trials. Meanwhile, structural knowledge of the ribosome, the target for aminoglycosides, has invigorated the field of antibiotic development. It is expected that knowledge of the binding interactions of aminoglycosides and the ribosome would lead to concepts in drug design that would take us away from the parental structures of aminoglycosides in the direction of different structural classes that bind to the same ribosomal target sites as aminoglycosides. The challenge to ensure the continued use of these highly potent antibacterial agents will require the effective management of resistance at several levels. One potential mechanism of circumventing resistance is the development of inhibitors of modification enzymes, a methodology that is now well established in the beta-lactam field. This approach requires knowledge of resistance at the molecular and atomic levels for the rational design of inhibitory molecules. The understanding of the molecular basis for aminoglycoside resistance modification has been greatly enhanced by the recent availability of representative 3D-structures from the three classes of modifying enzymes: kinases, acetyltransferases and adenyltransferases. The challenge is now to firmly establish the mechanisms of enzyme action and to use this information to prepare effective and potent inhibitors that will reverse antibiotic resistance. In this review, we discuss the molecular mechanisms of resistance of aminoglycosides specifically on aminoglycoside-modifying enzymes and newly developed strategies to circumvent resistance including antisense technology, which is an example of new strategy to deal with antibiotic resistance.

Measuring the impact of needle exchange programs among injecting drug users through the National Behavioural Surveillance in Bangladesh

Bangladesh is a low HIV prevalence country, with buprenorphine injectors having the highest prevalence of HIV at 2.5% as of 1999. Using National HIV Behavioral Surveillance data, the impact of a needle exchange program (NEP) on sharing behavior among injecting drug users in two cities was measured. Results showed positive changes that varied with the different settings. Those who reported utilizing the NEP were compared with those who did not. Differences in Dhaka were significant for the average proportion of needles shared but not for the proportion of men who ever shared in the last week. In Rajshahi, where professional injectors were the norm, the impact of an NEP was greater and affected both the proportion of needles shared as well as the proportion of men never sharing. Behavioral surveillance methods have the potential to measure intervention impact through comparative analysis in certain settings.