A scoping review of the experience of implementing population testing for SARS-CoV-2.

OBJECTIVES: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) - also known as the coronavirus disease (COVID-19) - pandemic has led to the swift introduction of population testing programmes in many countries across the world, using testing modalities such as drive-through, walk-through, mobile and home visiting programmes. Here, we provide an overview of the literature describing the experience of implementing population testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). STUDY DESIGN: Scoping review. METHODS: We conducted a scoping review using Embase, Medline and the Cochrane library in addition to a grey literature search. We identified indicators relevant to process, quality and resource outcomes related to each testing modality. RESULTS: In total, 2999 titles were identified from the academic literature and the grey literature search, of which 22 were relevant. Most studies were from the USA and the Republic of Korea. Drive-through testing centres were the most common testing modality evaluated and these provided a rapid method of testing whilst minimising resource use. CONCLUSIONS: The evidence base for population testing lacks high quality studies, however, the literature provides evaluations of the advantages and limitations of different testing modalities. There is a need for robust evidence in this area to ensure that testing is deployed in a safe and effective manner in response to the COVID-19 pandemic.

Systematic review, network meta-analysis and exploratory cost-effectiveness model of randomized trials of minimally invasive techniques versus surgery for varicose veins.

BACKGROUND: A Health Technology Assessment was conducted to evaluate the relative clinical effectiveness and cost-effectiveness of minimally invasive techniques (foam sclerotherapy (FS), endovenous laser ablation (EVLA) and radiofrequency ablation (RFA)) for managing varicose veins, in comparison with traditional surgery. METHODS: A systematic review of randomized clinical trials (RCTs) was undertaken to assess the effectiveness of minimally invasive techniques compared with other treatments, principally surgical stripping, in terms of recurrence of varicose veins, Venous Clinical Severity Score (VCSS), pain and quality of life. Network meta-analysis and exploratory cost-effectiveness modelling were performed. RESULTS: The literature search conducted in July 2011 identified 1453 unique citations: 31 RCTs (51 papers) satisfied the criteria for effectiveness review. Differences between treatments were negligible in terms of clinical outcomes, so the treatment with the lowest cost appears to be most cost-effective. Total FS costs were estimated to be lowest, and FS was marginally more effective than surgery. However, relative effectiveness was sensitive to the model time horizon. Threshold analysis indicated that EVLA and RFA might be considered cost-effective if their costs were similar to those for surgery. These findings are subject to various uncertainties, including the risk of bias present in the evidence base and variation in reported costs. CONCLUSION: This assessment of currently available evidence suggests there is little to choose between surgery and the minimally invasive techniques in terms of efficacy or safety, so the relative cost of the treatments becomes one of the deciding factors. High-quality RCT evidence is needed to verify and further inform these findings.

Colistimethate sodium powder and tobramycin powder for inhalation for the treatment of chronic Pseudomonas aeruginosa lung infection in cystic fibrosis: systematic review and economic model.

BACKGROUND: Cystic fibrosis (CF) is an inherited condition characterised by the abnormal transport of chloride ions across transporting epithelia. This leads to the production of thick sticky mucus in the lungs, pancreas, liver, intestine and reproductive tract, and an increase in the salt content in sweat. Among other problems, people with CF experience recurrent respiratory infections and have difficulties digesting food. CF affects over 9000 individuals in the UK. CF shortens life expectancy and adversely affects quality of life. In 2010, CF was recorded as the cause of 103 deaths in England and Wales. OBJECTIVE: To evaluate the clinical effectiveness and cost-effectiveness of colistimethate sodium dry powder for inhalation (DPI) (Colobreathe(®), Forest Laboratories) and tobramycin DPI (TOBI Podhaler(®), Novartis Pharmaceuticals) for the treatment of Pseudomonas aeruginosa lung infection in CF. DATA SOURCES: Electronic databases were searched in February and March 2011 [MEDLINE, MEDLINE In-Process & Other Non-Indexed citations, EMBASE, The Cochrane Library databases, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Science, Conference Proceedings Citation Index (CPCI) and Bioscience Information Service (BIOSIS) Previews]. Relevant databases were searched for ongoing and unpublished studies, and bibliographies of relevant systematic reviews and the manufacturers' submissions were also hand-searched. REVIEW METHODS: A systematic review of the clinical effectiveness and cost-effectiveness of colistimethate sodium DPI and tobramycin DPI for the treatment of chronic P. aeruginosa lung infection in CF was conducted. Existing economic evidence within the literature was reviewed and a de novo health economic model was also developed. RESULTS: Three randomised controlled trials (RCTs) were included in the clinical effectiveness review. Both colistimethate sodium DPI and tobramycin DPI were reported to be non-inferior to nebulised tobramycin for the outcome forced expiratory volume in first second percentage predicted (FEV1%). It was not possible to draw any firm conclusions as to the relative efficacy of colistimethate sodium DPI compared with tobramycin DPI. The economic analysis suggests that colistimethate sodium DPI produces fewer quality-adjusted life-years (QALYs) than nebulised tobramycin. Given the incremental discounted lifetime cost of tobramycin DPI compared with nebulised tobramycin, it highly unlikely that tobramycin DPI has an incremental cost-effectiveness ratio that is better than £30,000 per QALY gained. LIMITATION: The uncertainty surrounding the short-term evidence base inevitably results in uncertainty surrounding the long-term clinical effectiveness and cost-effectiveness of colistimethate sodium DPI. CONCLUSIONS: Both DPI formulations have been shown to be non-inferior to nebulised tobramycin as measured by FEV1%. The results of these trials should be interpreted with caution owing to the means by which the results were analysed, the length of follow-up, and concerns about the ability of FEV1% to accurately represent changes in lung health. Although the increase in QALYs is expected to be lower with colistimethate sodium DPI than with nebulised tobramycin, a price for this intervention had not been agreed at the time of the assessment. Depending on the price of colistimethate sodium DPI, this results either in a situation whereby colistimethate sodium DPI is dominated by nebulised tobramycin or in one whereby the incremental cost-effectiveness of nebulised tobramycin compared with colistimethate sodium DPI is in the range of £24,000-277,000 per QALY gained. The economic analysis also suggests that, given its price, it is unlikely that tobramycin DPI has a cost-effectiveness ratio of < £30,000 per QALY gained when compared with nebulised tobramycin. A RCT to assess the longer-term (≥ 12 months) efficacy of colistimethate sodium DPI and tobramycin DPI in comparison with nebulised treatments would be beneficial. Such a study should include the direct assessment of HRQoL using a relevant preference-based instrument. Future studies should ensure that the European Medicines Agency guidelines are adhered to. In addition, high-quality research concerning the relationship between forced expiratory volume in first second % (FEV1%) predicted or other measures of lung function and survival/health-related quality of life (HRQoL) would be useful. STUDY REGISTRATION: PROSPERO CRD42011001350. FUNDING: The National Institute for Health Research Health Technology Assessment programme.

Clinical effectiveness and cost-effectiveness of minimally invasive techniques to manage varicose veins: a systematic review and economic evaluation.

BACKGROUND: Varicose veins are enlarged, visibly lumpy knotted veins, usually in the legs. Uncomplicated varicose veins can cause major discomfort and some complications. They are part of chronic venous disease (CVD), which is reported to have a substantial negative impact on health-related quality of life (HRQoL). Traditional treatments for varicose veins involve surgical stripping and ligation and liquid sclerotherapy (LS), but can be invasive and painful. New minimally invasive treatments offer an alternative. These treatments typically involve use of laser, radiofrequency or foam sclerosant. They are increasingly widely used and offer potential benefits such as reduced complications, faster recovery, fewer physical limitations and improved quality of life. OBJECTIVE: The aim of this report is to evaluate the clinical effectiveness, safety and cost-effectiveness of the minimally invasive techniques of foam sclerotherapy (FS), endovenous laser ablation (EVLA) and radiofrequency ablation (RFA) in comparison with other techniques, including traditional surgical techniques, LS and conservative management, in the management of varicose veins. DATA SOURCES: A systematic search was made of 11 bibliographic databases of published and unpublished literature from their inception to July 2011: MEDLINE; EMBASE; Cumulative Index to Nursing and Allied Health Literature; The Cochrane Library; Biological Abstracts; Science Citation Index (SCI); Social Sciences Citation Index; Conference Proceedings Citation Index-Science; UK Clinical Research Network; Current Controlled Trials; and ClinicalTrials.gov. REVIEW METHODS: A systematic review of randomised controlled trials (RCTs) to assess the clinical effectiveness of minimally invasive techniques compared with other treatments, principally surgical stripping, in terms of recurrence of varicose veins, retreatment and clinical symptoms, as measured by the Venous Clinical Severity Score (VCSS), pain and quality of life. Network meta-analysis and exploratory cost-effectiveness modelling were performed. RESULTS: The literature search identified 1453 unique citations, of which 34 RCTs (54 papers) satisfied the criteria for the clinical effectiveness review. The minimally invasive techniques reported clinical outcomes similar to surgery. Rates of recurrence were slightly lower for EVLA, RFA and FS, especially for longer follow-up periods; VCSS score was lower for EVLA and FS than for stripping, but slightly higher for RFA; short-term pain was less for FS and RFA but higher for EVLA; higher quality-of-life scores were reported for all evaluated interventions than for stripping. Differences between treatments were therefore negligible in terms of clinical outcomes, so the treatment with the lowest cost appears to be most cost-effective. Our central estimate is that total FS costs were lowest and FS is marginally more effective than stripping. However, this result was sensitive to the model time horizon. Threshold analysis indicated that EVLA and RFA might be considered cost-effective if their costs are equivalent to stripping. These findings are subject to uncertainty on account of the risk of bias present in the evidence base and the variation in costs. LIMITATIONS: The relative clinical effectiveness and cost-effectiveness of the techniques are principally based on rates of post-operative technical recurrence rather than symptomatic recurrence, as this was the reported outcome in all trials. The true proportion of treated individuals who are likely to present with symptoms of recurrence requiring retreatment is therefore not certain. A figure reflecting the likely proportion of treated individuals who would experience symptomatic recurrence requiring retreatment (with its associated costs), therefore, had to be calculated by the authors based on a small number of studies. The findings of this report also need to be verified by data from future trials with longer follow-up and using more standardised outcome measures. CONCLUSIONS: This assessment of the currently available evidence suggests there is little to choose between the minimally invasive techniques in terms of efficacy or cost, and each offers a viable, clinically effective alternative to stripping. FS might offer the most cost-effective alternative to stripping, within certain time parameters. High-quality RCT evidence is needed. Future trials should aim to measure and report outcomes in a standardised manner, which would permit more efficient pooling of their results. STUDY REGISTRATION: PROSPERO number CRD42011001355. FUNDING: The National Institute for Health Research Health Technology Assessment programme.

Systematic review and meta-analysis of additional technologies to enhance angioplasty for infrainguinal peripheral arterial occlusive disease.

BACKGROUND: There are several additional techniques designed to enhance conventional percutaneous transluminal balloon angioplasty (PTA). This systematic review assessed current evidence on the clinical effectiveness of additional techniques for infrainguinal peripheral arterial occlusive disease (PAD). METHODS: Relevant electronic databases, including MEDLINE, were searched in May 2011. The population comprised participants with symptomatic PAD undergoing endovascular treatment for disease distal to the inguinal ligament. Interventions were additional techniques compared with conventional PTA. Main outcome measures were restenosis and need for reintervention. Randomized clinical trials (RCTs) of clinical effectiveness were assessed for quality and data were extracted. Where appropriate, meta-analysis was undertaken to produce risk ratios (RRs). RESULTS: Forty RCTs were selected. Meta-analysis showed a significant benefit in reducing restenosis rates at 6 months for self-expanding stents (RR 0.49) and drug-coated balloons (RR 0.40), and at 12 months for endovascular brachytherapy (RR 0.63). There was also evidence that use of a stent-graft significantly reduced restenosis compared with PTA, as did drug-eluting stents compared with bare-metal stents. Meta-analysis showed that use of drug-coated balloons was associated with significantly lower reintervention rates than PTA alone at 6 months (RR 0.24) and 24 months (RR 0.27) of follow-up. There was also evidence of significantly lower reintervention rates for self-expanding stents at 6 months. Other techniques did not show significant treatment effects for restenosis or reintervention. CONCLUSION: The conclusions of this review should be tempered by small sample sizes, lack of clinical outcome measures and differing outcome definitions, making direct comparison across trials difficult. However, self-expanding stents, drug-eluting stents and drug-coated balloons appeared to be the most promising technologies worthy of future study.

Device use, locomotor training and the presence of arm swing during treadmill walking after spinal cord injury.

STUDY DESIGN: Observational, cross-sectional study from a convenience sample with pretest/posttest data from a sample subset. OBJECTIVES: Determine the presence of walking-related arm swing after spinal cord injury (SCI), its associated factors and whether arm swing may change after locomotor training (LT). SETTING: Malcom Randall VAMC and University of Florida, Gainesville, FL. METHODS: Arm movement was assessed during treadmill stepping, pre-LT, in 30 individuals with motor incomplete SCI (iSCI, American Spinal Injury Association Impairment Scale grade C/D, as defined by the International Standards for Neurological Classifications of SCI, with neurological level of impairment at or below C4). Partial body weight support and manual-trainer assistance were provided, as needed, to achieve stepping and allow arm swing. Arm swing presence was compared on the basis of cervical versus thoracic neurological levels of impairment and device type. Leg and arm strength and walking independence were compared between individuals with and without arm swing. Arm swing was reevaluated post-LT in the 21 out of 30 individuals who underwent LT. RESULTS: Of 30 individuals with iSCI, 12 demonstrated arm swing during treadmill stepping, pre-LT. Arm movement was associated with device type, lower extremity motor scores and walking independence. Among the 21 individuals who received LT, only 5 demonstrated arm swing pre-LT. Of the 16 individuals lacking arm swing pre-LT, 8 integrated arm swing post-LT. CONCLUSION: Devices routinely used for walking post-iSCI appeared associated with arm swing. Post-LT, arm swing presence increased. Therefore, arm swing may be experience dependent. Daily neuromuscular experiences provided to the arms may produce training effects, thereby altering arm swing expression.

A survey of blood lead levels among young Johannesburg school children.

Studies conducted around the world have established beyond doubt that elevated childhood blood lead levels may lead to detrimental health effects. Research has shown that certain groups of South African children are at particular risk of elevated blood lead levels. Johannesburg is the largest urban complex in southern Africa, with a population of around 3 million and extensive industrial and manufacturing activity. Among the challenges posed in the city are rapid urbanization, extensive poverty, and inequity. Little information on the blood lead distribution of Johannesburg children is available. This study was undertaken to determine blood lead levels among children living in three areas of Johannesburg: inner city suburbs and the low-income townships of Alexandra and Westbury to the north and west of the city center, respectively. The results indicated that blood lead levels ranged from 6 to 26 micro g/dL, with a mean level of 11.9 micro g /dL. The blood lead levels of 78% of children equaled or exceeded 10 micro g/dL, the current international action level. Maternal educational status, the presence of smokers in the home, and living in an informal dwelling were among the factors associated with elevated blood lead levels.

Photochemical studies of 4-tert-butyl-4'-methoxydibenzoylmethane (BM-DBM).

Kinetic UV-VIS absorption data following 355 and 266 nm nanosecond laser flash photolysis of 4-tert-butyl-4'-methoxydibenzoylmethane (BM-DBM) solutions is presented. The kinetics of the decay of the non-chelated enol (NCE) produced following 355 nm excitation of BM-DBM solutions are analysed in terms of mixed 1st- and 2nd-order kinetics. The temperature dependences of the component rate constants are unusual and both 1st- and 2nd-order components display negative activation energies, which are explained by invoking pre-equilibria. In addition, it is shown for the first time that 266 nm laser photolysis of BM-DBM solutions leads to formation of the triplet state of the keto (K) form with a lifetime of approximately 500 ns. Under these conditions the triplet state of the K form is quenched by oxygen.

Photochemical studies of A2-E.

Lipofuscin is thought to be involved in age-related macular degeneration as is one of its proposed components, an amphiphillic pyridinium-based bis-retinoid with a quaternary nitrogen atom, known as A2-E. We report the triplet state spectra obtained from photosensitisation using anthracene and 1-nitronaphthalene in benzene and methanol. The triplet state of A2-E has lambda(max) at 550 nm and a lifetime of approximately 30 micros, it is efficiently quenched by molecular oxygen with a second-order quenching rate constant of approximately 1 x 10(9) dm(3) mol(-1) s(-1). There is no significant triplet state formation from direct laser excitation of A2-E and hence its quantum yield of triplet state formation must be <0.01.

Neuromodulation of Na+ channels: an unexpected form of cellular plasticity.

Voltage-gated Na+ channels set the threshold for action potential generation and are therefore good candidates to mediate forms of plasticity that affect the entire neuronal output. Although early studies led to the idea that Na+ channels were not subject to modulation, we now know that Na+ channel function is affected by phosphorylation. Furthermore, Na+ channel modulation is implicated in the control of input-output relationships in several types of neuron and seems to be involved in phenomena as varied as cocaine withdrawal, hyperalgesia and light adaptation. Here we review the available evidence for the regulation of Na+ channels by phosphorylation, its molecular mechanism, and the possible ways in which it affects neuronal function.

Dopaminergic modulation of voltage-gated Na+ current in rat hippocampal neurons requires anchoring of cAMP-dependent protein kinase.

Activation of D1-like dopamine (DA) receptors reduces peak Na(+) current in acutely isolated hippocampal neurons via a modulatory mechanism involving phosphorylation of the Na(+) channel alpha subunit by cAMP-dependent protein kinase (PKA). Peak Na(+) current is reduced 20-50% in the presence of the D1 agonist SKF 81297 or the PKA activator Sp-5,6-dichloro-l-beta-d-ribofuranosyl benzimidazole-3',5'-cyclic monophosphorothionate (cBIMPS). Co-immunoprecipitation experiments show that Na(+) channels are associated with PKA and A-kinase-anchoring protein 15 (AKAP-15), and immunocytochemical labeling reveals their co-localization in the cell bodies and proximal dendrites of hippocampal pyramidal neurons. Anchoring of PKA near the channel by an AKAP, which binds the RII alpha regulatory subunit, is necessary for Na(+) channel modulation in acutely dissociated hippocampal pyramidal neurons. Intracellular dialysis with the anchoring inhibitor peptides Ht31 from a human thyroid AKAP and AP2 from AKAP-15 eliminated the modulation of the Na(+) channel by the D1-agonist SKF 81297 and the PKA activator cBIMPS. In contrast, dialysis with the inactive proline-substituted control peptides Ht31-P and AP2-P had little effect on the D1 and PKA modulation. Therefore, we conclude that modulation of the Na(+) channel by activation of D1-like DA receptors requires targeted localization of PKA near the channel to achieve phosphorylation of the alpha subunit and to modify the functional properties of the channel.

Voltage-dependent neuromodulation of Na+ channels by D1-like dopamine receptors in rat hippocampal neurons.

Activation of D1-like dopamine (DA) receptors reduces peak Na+ current in acutely isolated hippocampal neurons through phosphorylation of the alpha subunit of the Na+ channel by cAMP-dependent protein kinase (PKA). Here we report that neuromodulation of Na+ currents by DA receptors via PKA is voltage-dependent in the range of -110 to -70 mV and is also sensitive to concurrent activation of protein kinase C (PKC). Depolarization enhanced the ability of D1-like DA receptors to reduce peak Na+ currents via the PKA pathway. Similar voltage-dependent modulation was observed when PKA was activated directly with the membrane-permeant PKA activator DCl-cBIMPS (cBIMPS; 20 microM), indicating that the membrane potential dependence occurs downstream of PKA. PKA activation caused only a small (-2.9 mV) shift in the voltage dependence of steady-state inactivation and had no effect on slow inactivation or on the rates of entry into the fast or slow inactivated states, suggesting that another mechanism is responsible for coupling of membrane potential changes to PKA modulation. Activation of PKC with a low concentration of the membrane-permeant diacylglycerol analog oleylacetyl glycerol also potentiated modulation by SKF 81297 or cBIMPS, and these effects were most striking at hyperpolarized membrane potentials where PKA modulation was not stimulated by membrane depolarization. Thus, activation of D1-like DA receptors causes a strong reduction in Na+ current via the PKA pathway, but it is effective primarily when it is combined with depolarization or activation of PKC. The convergence of these three distinct signaling modalities on the Na+ channel provides an intriguing mechanism for integration of information from multiple signaling pathways in the hippocampus and CNS.

Interaction of batrachotoxin with the local anesthetic receptor site in transmembrane segment IVS6 of the voltage-gated sodium channel.

The voltage-gated sodium channel is the site of action of more than six classes of neurotoxins and drugs that alter its function by interaction with distinct, allosterically coupled receptor sites. Batrachotoxin (BTX) is a steroidal alkaloid that binds to neurotoxin receptor site 2 and causes persistent activation. BTX binding is inhibited allosterically by local anesthetics. We have investigated the interaction of BTX with amino acid residues I1760, F1764, and Y1771, which form part of local anesthetic receptor site in transmembrane segment IVS6 of type IIA sodium channels. Alanine substitution for F1764 (mutant F1764A) reduces tritiated BTX-A-20-alpha-benzoate binding affinity, causing a 60-fold increase in Kd. Alanine substitution for I1760, which is adjacent to F1764 in the predicted IVS6 transmembrane alpha helix, causes only a 4-fold increase in Kd. In contrast, mutant Y1771A shows no change in BTX binding affinity. For wild-type and mutant Y1771A, BTX shifted the voltage for half-maximal activation approximately 40 mV in the hyperpolarizing direction and increased the percentage of noninactivating sodium current to approximately 60%. In contrast, these BTX effects were eliminated completely for the F1764A mutant and were reduced substantially for mutant I1760A. Our data suggest that the BTX receptor site shares overlapping but nonidentical molecular determinants with the local anesthetic receptor site in transmembrane segment IVS6 as well as having unique molecular determinants in transmembrane segment IS6, as demonstrated in previous work. Evidently, BTX conforms to a domain-interface allosteric model of ligand binding and action, as previously proposed for calcium agonist and antagonist drugs acting on L-type calcium channels.

Lead absorption and renal dysfunction in a South African battery factory.

OBJECTIVES: To test the association between inorganic lead (Pb) exposure, blood pressure, and renal function in South African battery factory workers, with both conventional and newer measures of renal function and integrity. METHODS: Renal function measures included serum creatinine, urea, and urate (n = 382). Urinary markers (n = 199) included urinary N-acetyl-beta-D-glucosaminidase (NAG), retinol binding protein, intestinal alkaline phosphatase, tissue non-specific alkaline phosphatase, Tamm-Horsfall glycoprotein, epidermal growth factor, and microalbuminuria. RESULTS: Mean current blood Pb was 53.5 micrograms/dl (range 23 to 110), median zinc protoporphyrin 10.9 micrograms/g haemoglobin (range 1.9 to 104), and mean exposure duration 11.6 years (range 0.5 to 44.5). Mean historical blood Pb, available on 246 workers, was 57.3 micrograms/dl (range 14 to 96.3). After adjustment for age, weight and height, positive exposure response relations were found between current blood Pb, historical blood Pb, zinc protoporphyrin (ZPP), and serum creatinine and urate. Blood pressure was not associated with Pb exposure. Among the urinary markers, only NAG showed a positive association with current and historical blood Pb. CONCLUSION: An exposure-response relation between Pb and renal dysfunction across the range from < 40 to > 70 micrograms/dl blood Pb was found in this workforce, with conventional measures of short and long term Pb exposure and of renal function. This could not be explained by an effect on blood pressure, which was not associated with Pb exposure. The findings probably reflect a higher cumulative renal burden of Pb absorption in this workforce in comparison with those in recent negative studies. The results also confirm the need for strategies to reduce Pb exposure among industrial workers in South Africa.

Semen quality and fertility of men employed in a South African lead acid battery plant.

Previous studies of the associations of measures of occupational lead exposure with measures of semen quality and infertility among male workers have produced conflicting results. The current study was undertaken to examine these associations among a population of workers with a broad range of measures of current and historical lead exposure. Ninety-seven lead-exposed workers from a South African lead acid battery facility provided semen samples that were analyzed for sperm density, sperm count, sperm motility, sperm morphology, and presence of antisperm antibodies. Questionnaire data were collected for reported histories of sub- or infertility. Current blood leads ranged from 28 to 93 micrograms/dl. Semen lead ranged from 1 to 87 micrograms/dl. Reasonably consistent and significant associations were found between an increased percentage of sperm with abnormal morphology and higher measures of current blood lead, cumulative blood lead, and duration of exposure. An increased percent of immotile sperm was associated only with zinc protoporphyrin (ZPP) among the lead exposure measures. There were no associations of sperm density or sperm count with any of the lead exposure measures. A weak association of increased percent of sperm with antisperm antibodies with increased semen lead was present. There were no consistent associations of measures of lead exposure with measures of fertility or procreativity. This study, while supporting the association of lead exposure with increased risk of abnormal sperm morphology seen in some previous studies, does not lend support to previously reported associations of sperm density or count or infertility with measures of lead exposure. However, the relatively high range of current blood leads, high prevalence of abnormalities in semen quality, and the lack of a control population, suggest that these negative findings should be interpreted with caution.

Dopaminergic modulation of sodium current in hippocampal neurons via cAMP-dependent phosphorylation of specific sites in the sodium channel alpha subunit.

Phosphorylation of brain Na+ channel alpha subunits by cAMP-dependent protein kinase (PKA) decreases peak Na+ current in cultured brain neurons and in mammalian cells and Xenopus oocytes expressing cloned brain Na+ channels. We have studied PKA regulation of Na+ channel function by activation of D1-like dopamine receptors in acutely isolated hippocampal neurons using whole-cell voltage-clamp recording techniques. The D1 agonist SKF 81297 reversibly reduced peak Na+ current in a concentration-dependent manner. No changes in the voltage dependence or kinetics of activation or inactivation were observed. This effect was mediated by PKA, as it was mimicked by application of the PKA activator Sp-5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole-3', 5'-monophosphorothioate(cBIMPS) and was inhibited by the specific PKA inhibitor peptide PKAI5-24. cBIMPS had similar effects on type IIA brain Na+ channel alpha subunits expressed in tsA-201 cells, but no effect was observed on a mutant Na+ channel alpha subunit in which serine residues in five PKA phosphorylation sites in the intracellular loop connecting domains I and II (LI-II) had been replaced by alanine. A single mutation, S573A, similarly eliminated cBIMPS modulation. Thus, activation of D1-like dopamine receptors results in PKA-dependent phosphorylation of specific sites in LI-II of the Na+ channel alpha subunit, causing a reduction in Na+ current. Such modulation is expected to exert a profound influence on overall neuronal excitability. Dopaminergic input to the hippocampus from the mesocorticolimbic system may exert this influence in vivo.

Phenethylthiazolylthiourea (PETT) compounds as a new class of HIV-1 reverse transcriptase inhibitors. 2. Synthesis and further structure-activity relationship studies of PETT analogs.

Phenylethylthiazolylthiourea (PETT) derivatives have been identified as a new series of non-nucleoside inhibitors of HIV-1 RT. Structure-activity relationship studies of this class of compounds resulted in the identification of N-[2-(2-pyridyl)ethyl]-N'-[2-(5-bromopyridyl)]-thiourea hydrochloride (trovirdine; LY300046.HCl) as a highly potent anti-HIV-1 agent. Trovirdine is currently in phase one clinical trials for potential use in the treatment of AIDS. Extension of these structure-activity relationship studies to identify additional compounds in this series with improved properties is ongoing. A part of this work is described here. Replacement of the two aromatic moieties of the PETT compounds by various substituted or unsubstituted heteroaromatic rings was investigated. In addition, the effects of multiple substitution in the phenyl ring were also studied. The antiviral activities were determined on wild-type and constructed mutants of HIV-1 RT and on wild-type HIV-1 and mutant viruses derived thereof, Ile100 and Cys181, in cell culture assays. Some selected compounds were determined on double-mutant viruses, HIV-1 (Ile 100/Asn103) and HIV-1 (Ile100/Cys181). A number of highly potent analogs were synthesized. These compounds displayed IC50's against wild-type RT between 0.6 and 5 nM. In cell culture, these agents inhibited wild-type HIV-1 with ED50's between 1 and 5 nM in MT-4 cells. In addition, these derivatives inhibited mutant HIV-1 RT (Ile 100) with IC50's between 20 and 50 nM and mutant HIV-1 RT (Cys 181) with IC50's between 4 and 10 nM, and in cell culture they inhibited mutant HIV-1 (Ile100) with ED50's between 9 and 100 nM and mutant HIV-1 (Cys181) with ED50's between 3 and 20 nM.

Biological indicators of exposure to total and respirable aluminium dust fractions in a primary aluminium smelter.

OBJECTIVES: The study attempts to define biological indicators of aluminium uptake and excretion in workers exposed to airborne aluminium compounds in a primary aluminium smelter. Also, this study defines the total and respirable aluminium dust fractions in two different potrooms, and correlates their concentrations with biological indicators in this group of workers. METHODS: Air was sampled at defined work sites. Non-destructive and conventional techniques were used to find total and respirable aluminium content of the dust. Blood and urine was collected from 84 volunteers employed at various work stations throughout the smelter and from two different cohorts of controls matched for sex, age, and socioeconomic status. Aluminium in serum samples and urine specimens was measured by flameless atomic absorption with a PE 4100 ZL spectrometer. RESULTS: The correlation of aluminium concentrations in serum and urine samples with the degree of exposure was assessed for three arbitrary exposure categories; low (0.036 mg Al/m3), medium (0.35 mg Al/m3) and high (1.47 mg Al/m3) as found in different areas of the smelter. At medium and high exposure, the ratio of respirable to total aluminium in the dust samples varied significantly. At high exposure, serum aluminium, although significantly raised, was still within the normal range of an unexposed population. The workers with low exposure excreted aluminium in urine at levels significantly higher than the controls, but still within the normal range of the population. However, potroom workers with medium and high exposure had significantly higher urinary aluminium than the normal range. CONCLUSIONS: It is concluded that only urinary aluminium constitutes a practical index of occupational exposure at or above 0.35 mg Al/m3, and that the respirable fraction of the dust may play a major role in the biological response to exposure to aluminium in a smelter environment.

Muscarinic modulation of sodium current by activation of protein kinase C in rat hippocampal neurons.

Phosphorylation of brain Na+ channels by protein kinase C (PKC) decreases peak Na+ current and slows macroscopic inactivation, but receptor-activated modulation of Na+ currents via the PKC pathway has not been demonstrated. We have examined modulation of Na+ channels by activation of muscarinic receptors in acutely-isolated hippocampal neurons using whole-cell voltage-clamp recording. Application of the muscarinic agonist carbachol reduced peak Na+ current and slowed macroscopic inactivation at all potentials, without changing the voltage-dependent properties of the channel. These effects were mediated by PKC, since they were eliminated when the specific PKC inhibitor (PKCI19-36) was included in the pipette solution and mimicked by the extracellular application of the PKC activator, OAG. Thus, activation of endogenous muscarinic receptors on hippocampal neurons strongly modulates Na+ channel activity by activation of PKC. Cholinergic input from basal forebrain neurons may have this effect in the hippocampus in vivo.

Phenethylthiazolethiourea (PETT) compounds, a new class of HIV-1 reverse transcriptase inhibitors. 1. Synthesis and basic structure-activity relationship studies of PETT analogs.

A novel series of potent specific HIV-1 inhibitory compounds is described. The lead compound in the series, N-(2-phenethyl)-N'-(2-thiazolyl)thiourea (1), inhibits HIV-1 RT using rCdG as the template with an IC50 of 0.9 microM. In MT-4 cells, compound 1 inhibits HIV-1 with an ED50 of 1.3 microM. The 50% cytotoxic dose in cell culture is > 380 microM. The chemical structure-activity relationship (SAR) was developed by notionally dividing the lead compound in four quadrants. The SAR strategy had two phases. The first phase involved optimization of antiviral activity through independent variation of quadrants 1-4. The second phase involved the preparation of hybrid structures combining the best of these substituents. Further SAR studies and pharmacokinetic considerations led to the identification of N-(2-pyridyl)-N'-(5-bromo-2-pyridyl)-thiourea (62; LY300046.HCl) as a candidate for clinical evaluation. LY300046.HCl inhibits HIV-1 RT with an IC50 of 15 nM and in cell culture has an ED50 of 20 nM.