Immunogenicity of recombinant protective antigen and efficacy against aerosol challenge with anthrax

Immunization with a recombinant form of the protective antigen (rPA) from Bacillus anthracis has been carried out with rhesus macaques. Rhesus macaques immunized with 25 mug or more of B. subtilis-expressed rPA bound to alhydrogel had a significantly increased immunoglobulin G (IgG) response to rPA compared with macaques receiving the existing licensed vaccine from the United Kingdom (anthrax vaccine precipitated [AVP]), although the isotype profile was unchanged, with bias towards the IgG1 and IgG2 subclasses. Immune macaque sera from all immunized groups contained toxin-neutralizing antibody and recognized all the domains of PA. While the recognition of the N terminus of PA (domains 1 to 3) was predominant in macaques immunized with the existing vaccines (AVP and the U.S. vaccine anthrax vaccine adsorbed), macaques immunized with rPA recognized the N- and C-terminal domains of PA. Antiserum derived from immunized macaques protected macrophages in vitro against the cytotoxic effects of lethal toxin. Passive transfer of IgG purified from immune macaque serum into naive A/J mice conferred protection against challenge with B. anthracis in a dose-related manner. The protection conferred by passive transfer of 500 mug macaque IgG correlated significantly (P = 0.003; r = 0.4) with the titers of neutralizing antibody in donor macaques. Subsequently, a separate group of rhesus macaques immunized with 50 mug of Escherichia coli-derived rPA adsorbed to alhydrogel was fully protected against a target dose of 200 50% lethal doses of aerosolized B. anthracis. These data provide some preliminary evidence for the existence of immune correlates of protection against anthrax infection in rhesus macaques immunized with rPA.

Consensus statement. Workshop on therapeutic resistance in breast cancer: impact of growth factor signalling pathways and implications for future treatment

Anti-hormones (notably tamoxifen), chemotherapy and modern radiotherapeutic approaches are invaluable in the management of breast cancer, and collectively have contributed substantially to the improved survival in this disease. Moreover, there is promise that these successes will continue with the emergence of other endocrine agents (for example, aromatase inhibitors and pure anti-oestrogens). However, de novo and acquired resistance comprises a significant problem with all treatment approaches examined to date. This Workshop aimed to evaluate the contribution made by growth factor signalling pathways in the various resistant states, primarily focusing on resistance to anti-hormonal strategies and spanning experimental models and, where possible, clinical breast cancer data. The successes and limitations of therapeutic targeting of these pathways with various signal transduction inhibitors (STIs) were evaluated in model systems and from emerging clinical trials (including epidermal growth factor receptor inhibitors such as gefitinib). It was concluded that growth factor signalling is an important contributor in the development of endocrine resistance in breast cancer and that use of STIs provides a promising therapeutic strategy for this disease. However, the cancer cell is clearly able to harness alternative growth factor signalling pathways for growth and cell survival in the presence of STI monotherapy and, as a consequence, the efficacy of STIs is likely to be limited by the acquisition of resistance. A number of strategies were proposed from studies in model systems that appeared to enhance anti-tumour actions of existing STI monotherapy, notably including combination therapies targeting multiple pathways. With the increased availability of diverse STIs and improved drug delivery, there is much hope that the more complex therapeutic strategies proposed may ultimately be achievable in clinical practice.

Development of strategies for the use of anti-growth factor treatments

Aberrant signalling through the epidermal growth factor receptor (EGFR) is associated with increased cancer cell proliferation, reduced apoptosis, invasion and angiogenesis. Over-expression of the EGFR is seen in a variety of tumours and is a rational target for antitumour strategies. Among the classes of agent targeting the EGFR are small-molecule inhibitors, which include gefitinib (IRESSA), which acts by preventing EGFR phosphorylation and downstream signal transduction. De novo and acquired resistance, however, have been reported to gefitinib and here we describe evidence which indicates that the type II receptor tyrosine kinases (RTKs) insulin-like growth factor-I receptor (IGF-IR) and/or insulin receptor (InsR) play important roles in the mediation of responses to gefitinib in the de novo- and acquired-resistance phenotypes in several cancer types. Moreover, combination strategies that additionally target the IGF-IR/InsR can enhance the antitumour effects of gefitinib.

Growth factor signalling networks in breast cancer and resistance to endocrine agents: new therapeutic strategies

Recent evidence demonstrates that growth factor networks are highly interactive with the estrogen receptor (ER) in the control of breast cancer growth and development. As such, tumor responses to anti-hormones are likely to be a composite of the ER and growth factor inhibitory activity of these agents, with alterations/aberrations in growth factor signalling providing a mechanism for the development of anti-hormone resistance. In this light, the current article focuses on illustrating the relationship between growth factor signalling and anti-hormone failure in our in-house tumor models of breast cancer and describes how we are now beginning to successfully target their actions to improve the effects of anti-hormonal drugs and to block aggressive disease progression.

Insulin-like growth factor-I receptor signalling and acquired resistance to gefitinib (ZD1839; Iressa) in human breast and prostate cancer cells

De novo and acquired resistance to the anti-tumour drug gefitinib (ZD1839; Iressa), a specific epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) has been reported. We have determined whether signalling through the IGF-I receptor (IGF-1R) pathway plays a role in the gefitinib-acquired resistance phenotype. Continuous exposure of EGFR-positive MCF-7-derived tamoxifen resistant breast cancer cells (TAM-R) to 1 microM gefitinib resulted in a sustained growth inhibition (90%) for 4 months before the surviving cells resumed proliferation. A stable gefitinib-resistant subline (TAM/TKI-R) was established after a further 2 months and this showed no detectable basal phosphorylated EGFR activity. Compared with the parental TAM-R cells, the TAM/ TKI-R cells demonstrated (a) elevated levels of activated IGF-1R, AKT and protein kinase C (PKC)delta, (b) an increased sensitivity to growth inhibition by the IGF-1R TKI AG1024 and (c) an increased migratory capacity that was reduced by AG1024 treatment. Similarly, the EGFR-positive androgen-independent human prostate cancer cell line DU145 was also continuously challenged with 1 microM gefitinib and, although substantial growth inhibition (60%) was seen initially, a gefitinib-resistant variant (DU145/TKI-R) developed after 3 months. Like their breast cancer counterparts, the DU145/TKI-R cells showed increases in the levels of components of the IGF-1R signalling pathway and an elevated sensitivity to growth inhibition by AG1024 compared with the parent DU145 cell line. Additionally, DU145/TKI-R cell migration was also decreased by this inhibitor. We have therefore concluded that in breast and prostate cancer cells acquired resistance to gefitinib is associated with increased signalling via the IGF-1R pathway, which also plays a role in the invasive capacity of the gefitinib-resistant phenotype.

A multidrug efflux phenotype mutant of Streptococcus pyogenes

We describe a mutant of Streptococcus pyogenes NCTC 8198 with a multidrug efflux phenotype. A mutant selected with ethidium bromide showed a four-fold rise in MIC of norfloxacin, a 16-fold rise in MIC of ethidium bromide and an eight-fold rise in MIC of acriflavine when compared with the parent strain. The MICs were unaffected by the efflux pump inhibitors reserpine, rescinnamine and verapamil. The mutant's ethidium bromide MIC was reduced two-fold by norfloxacin. Ethidium bromide accumulation after 10 min was 58% lower in the mutant compared with the parent. This difference was not affected by carbonyl cyanide m-chlorophenylhydrazone.

Spatial organization and magnitude of orientation contrast interactions in primate V1

We have explored the spatial organization of orientation contrast effects in primate V1. Our stimuli were either concentric patches of drifting grating of varying orientation and diameter or grating patches displaced in x-y coordinates around a central patch overlying the classical receptive field (CRF). All cells in the sample exhibited response suppression to iso-oriented stimuli exceeding the CRF. Changing the outer stimulus orientation revealed five response patterns: 1) orientation alignment suppression (17% of cells)-a suppressive component tuned to the same orientation as the cell's optimal, 2) orientation contrast facilitation (63%)-responses to orientation contrast stimuli exceeded those to the center stimulus alone, 3) nonorientation specific suppression (3%), 4) mixed general suppression and alignment suppression (14%), and 5) orientation contrast suppression (14%)-cross-oriented stimuli evoked stronger suppression than iso-oriented stimuli. Thus most cells (94%) showed larger responses to orientation contrast stimuli than to iso-oriented stimuli, and over one-half showed orientation contrast facilitation. There appeared to be a spatially structured organization of the zones driving the different response patterns with respect to the CRF. Nonorientation-specific suppression and orientation contrast suppression were predominantly evoked by orientation contrast borders located within the CRF, and orientation contrast facilitation was mainly driven by surround stimuli lying outside the CRF. This led to different response patterns according to border location. Zones driving orientation contrast facilitation were not necessarily contiguous to, nor uniformly distributed around, the CRF. Our data support two processes underlying orientation contrast enhancement effects: a simple variation in the strength of surround suppression drawing on the fact that surround suppression is tuned to the same orientation as the CRF and a second process driven by orientation contrast that enhanced cells' responses to CRF stimulation by either dis-inhibition or orientation contrast facilitation. We suggest these processes may serve to enhance response levels to salient image features such as junctions and corners and may contribute to orientation pop-out.

Direct measurement of free Ca(2+) shows different regulation of Ca(2+) between the periplasm and the cytosol of Escherichia coli

As in eukaryotes, bacterial free Ca(2+) can play an important role as an intracellular signal. However, because free Ca(2+) is difficult to measure in live bacteria, most of the evidence for such a role is indirect. Gram-negative bacteria also have an outer membrane separating the external fluid from the periplasm as well as the cytosol where most bacterial metabolism takes place. Here we report, for the first time, direct measurement of free Ca(2+) in the periplasmic space of living Escherichia coli. Periplasmic free Ca(2+) was measured by targeting the Ca(2+)-activated photoprotein aequorin to this compartment using the N-terminal OmpT signal sequence. Cytosolic free Ca(2+) was determined using aequorin alone. We show that, under certain conditions, the periplasm can concentrate free Ca(2+), resulting in the inner membrane being exposed to free Ca(2+) concentrations several fold higher than in the bulk external fluid. Manipulation of periplasmic membrane-derived oligosaccharides (MDOs) altered the free Ca(2+) as predicted by the Donnan potential. With micromolar concentrations of external free Ca(2+), the periplasm concentrated free Ca (2+) some three to sixfold with respect to the external medium. A Ca(2+) gradient also existed between the periplasm and the cytosol under these conditions, the periplasmic free Ca(2+) being some one to threefold higher. At millimolar levels of external free Ca(2+), a similar concentration was detected in the periplasm, but the bacteria still maintained tight control of cytosolic free Ca(2+) in the micromolar range. We propose that the highly anionic MDOs in the periplasmic space generate a Donnan potential, capable of concentrating Ca(2+) in this compartment, where it may constitute a sink for regulation of Ca(2+)-dependent processes in the cytoplasm.

Modulation of epidermal growth factor receptor in endocrine-resistant, estrogen-receptor-positive breast cancer

An increasing body of evidence demonstrates that growth factor networks are highly interactive with estrogen receptor signaling in the control of breast cancer growth. As such, tumor responses to antihormones are likely to be a composite of the estrogen receptor and growth factor inhibitory activity of these agents. The modulation of growth factor networks during endocrine response is examined, and in vitro and clinical evidence is presented that epidermal growth factor receptor signaling, maintained in either an estrogen receptor-dependent or a receptor-independent manner, is critical to antihormone-resistant breast cancer cell growth. The considerable potential of the epidermal growth factor receptor-selective tyrosine kinase inhibitor Iressa (ZD 1839) to efficiently treat, and perhaps even prevent, endocrine-resistant breast cancer is highlighted.

Surround suppression in primate V1

We investigated the spatial organization of surround suppression in primate primary visual cortex (V1). We utilized drifting stimuli, configured to extend either from within the classical receptive field (CRF) to surrounding visual space, or from surrounding visual space into the CRF or subdivided to generate direction contrast, to make a detailed examination of the strength, spatial organization, direction dependence, mechanisms, and laminar distribution of surround suppression. Most cells (99/105, 94%) through all cortical layers, exhibited suppression (mean reduction 67%) to uniform stimuli exceeding the CRF, and 43% exhibited a more than 70% reduction. Testing with an annulus revealed two different patterns of surround influence. Some cells (37% of cells), classical surround suppression (CSS) cells exhibited responses to an annulus encroaching on the CRF that were less than the plateau in the spatial summation curve. The majority (63%), center-gated surround suppression (CGSS) cells, showed responses to annuli that equaled or exceeded the plateau in the spatial summation curve. Analysis suggested the CSS mechanism was implemented in all cells while the CGSS mechanism was implemented in varying strength across the sample with the extreme reflected in cells that gave larger responses to annuli than to a center stimulus. Reversing the direction of motion of the portion of the stimulus surrounding the CRF revealed four different patterns of effect: no reduction in the degree of suppression (22% of cells), a reduction in surround suppression (41%), a facilitation of the response above the level to the inner stimulus alone (37%), and a facilitation of the response above that to the inner stimulus alone that also exceeded the values associated with an optimal inner stimulus. The facilitatory effects were only seen for reverse direction interfaces between the central and surrounding stimulus at diameters equal to or more than the CRF size. The zones driving the suppressive influences and the direction contrast facilitation were often spatially heterogeneous and for a number of cells bore strong comparison with the class of behavior reported for surround mechanisms in MT. This suggests a potential role, for example, in extracting information about motion contrast in the representation of the three dimensional structure of moving objects.

Effect of an EGF-R selective tyrosine kinase inhibitor and an anti-androgen on LNCaP cells: identification of divergent growth regulatory pathways

BACKGROUND

The effect of an EGF-R selective tyrosine kinase (EGF-RTK) quinazoline inhibitor ZM252868 was determined on the androgen-sensitive human prostatic tumour cell line LNCaP, which can also respond via the EGF-R-regulated growth pathway for cell proliferation. Potential interaction or 'cross-talk' between steroid and the growth factor mitogen-activated protein kinase (MAPK) signalling pathway was also investigated.

METHODS

The responses of LNCaP cells to various growth factors in the absence and presence of the EGF-RTK inhibitor and/or steroid and anti-androgen Casodex, was determined using cell population analysis. The effect of the inhibitor on the expression of androgen receptor, EGF-R and activated MAPK was assessed immunocytochemically and changes in the MAPK signalling cascade were also determined using Western blotting techniques.

RESULTS

The ZM252868 inhibitor had no effect on LNCaP basal growth. At 100 nM and 1 microM concentrations, the inhibitor reduced the marked EGF- and TGF-alpha-stimulated LNCaP cell growth by 60% and to basal levels, respectively. Both bFGF- and 5alpha-DHT-stimulated growth were unaffected in this concentration range. The inhibitor (1 microM) decreased the expression of immunoreactive EGF-R but had no effect on androgen receptor levels. Activation of MAPK by EGF was noted, being down-regulated by the inhibitor at a concentration of 1 microM. MAPK was not activated by 5alpha-DHT. The anti-androgen Casodex reduced 5alpha-DHT-stimulated cell growth but had no effect on EGF-R mediated LNCaP growth or EGF-stimulated activated MAPK activity. Treatment with EGF and 5alpha-DHT in combination produced an additive effect on cell proliferation, with the anti-androgen and the EGF-RTK inhibitor only reducing the 5alpha-DHT- or EGF-stimulated portion of growth, respectively.

CONCLUSIONS

The study demonstrated the efficacy and selectivity of the ZM252868 inhibitor in inhibiting EGF-R mediated LNCaP cell growth. Additionally, no interaction between androgen and EGF-R mediated growth pathways was determined.

Modulation of epidermal growth factor receptor in endocrine-resistant, oestrogen receptor-positive breast cancer

There is an increasing body of evidence demonstrating that growth factor networks are highly interactive with oestrogen receptor (ER) signalling in the control of breast cancer growth. As such, tumour responses to anti- hormones are likely to be a composite of the ER and growth factor inhibitory activity of these agents. The current article examines the modulation of growth factor networks during endocrine response, and presents in vitro and clinical evidence that epidermal growth factor receptor signalling, maintained in either an ER-dependent or -independent manner, is critical to anti- hormonal-resistant breast cancer cell growth. The considerable potential of the epidermal growth factor receptor-selective tyrosine kinase inhibitor, ZD 1839 (Iressa; AstraZeneca) to efficiently treat, and perhaps even prevent, endocrine-resistant breast cancer is highlighted.

Physiological, subjective and reinforcing effects of oral and intravenous cocaine in humans

RATIONALE

There is little comparative information on the qualitative similarity, relative potency and reinforcing effects of oral cocaine versus cocaine administered via other routes.

METHODS

The present study used a within-subject, double-blind, double-dummy design to compare the physiological, subjective and reinforcing effects of placebo and oral (62.5, 125, 250 mg/70 kg) and intravenous (IV) (12.5, 25, 50 mg/70 kg) cocaine in volunteers with histories of cocaine abuse.

RESULTS

Cocaine produced dose-dependent increases on heart rate and blood pressure, with effects lasting longer after oral than IV cocaine. Subjective ratings (e.g., "rush," "drug effect," "liking") were qualitatively similar and dose-dependently increased after oral and IV administration, and the duration of effects was similar under both routes. On a money versus drug choice measure of reinforcement, the monetary amounts at which participants chose drug over money increased as a function of cocaine dose under both routes of administration. At doses that produced comparable subjective, physiological, and reinforcing effects, oral cocaine was not identified as cocaine as frequently as IV cocaine. Across measures, the data suggested that IV cocaine was approximately 10 times more potent than oral cocaine.

CONCLUSIONS

Overall, the results of this study support qualitatively similar effects of oral and IV cocaine and suggest that oral cocaine may be an effective tool for studying cocaine's effects in human laboratory studies.

Buprenorphine treatment of pregnant opioid--dependent women: maternal and neonatal outcomes

This open-label prospective study examined maternal and neonatal safety and efficacy outcome measures during and following prenatal buprenorphine exposure. Three opioid-dependent pregnant women received 8 or 12 mg sublingual buprenorphine tablets daily for 15-16 weeks prior to delivery. Results showed that buprenorphine in combination with comprehensive prenatal care was safe and effective in these women. Prenatal exposure to buprenorphine resulted in normal birth outcomes, a mean of 4.33 days (minimum possible=4) hospitalization, and a 'relatively mild' neonatal abstinence syndrome comprised primarily of tremors (disturbed), hyperactive moro and shortened sleep after feeding. The infants required no pharmacological treatment. Onset of neonatal abstinence signs occurred within the first 12 h after birth, peaked by 72 h and returned to below pre-12 h levels by 120 h. It is concluded that buprenorphine has potential utility for the treatment of pregnant opioid-dependent women.

Factors involved in producing a sustained experimental dermatophyte infection (Trichophyton mentagrophytes)

Dr. Jones applied different concentrations of living dermatophyte spores to the surface of uninfected skin under occluded conditions. He then followed the subjects to observe any developing infection and determine the minimum number of spores needed to induce infection.

Clinical and psychosocial characteristics of substance-dependent pregnant women with and without PTSD

The present study compared psychiatric and psychosocial functioning in 123 pregnant opiate- and/or cocaine-dependent women with and without a comorbid diagnosis of posttraumatic stress disorder (PTSD). Participants were enrolled in a comprehensive perinatal drug treatment program and completed assessments upon admission. Lifetime diagnostic prevalence of PTSD [Structured Clinical Interview for DSM-IV Disorders (SCID) confirmed] among the sample was 19%. Participants with PTSD (n=24) reported greater need for psychiatric treatment, were more likely to report a previous suicide attempt, and had more previous drug treatments than participants without PTSD (n=99). Women with PTSD were twice as likely to have lifetime Axis I and Axis II disorders and had higher rates of abuse than women without PTSD. Lifetime sexual abuse and ASI family/social composite scores were significant predictors of PTSD. Findings suggest that pregnant drug-dependent women with comorbid PTSD may benefit from specialized treatment services for trauma and/or abuse issues.

Reinforcing effects of oral cocaine: contextual determinants

RATIONALE

Although the behavioral, subjective, and physiological effects of oral cocaine have been investigated, its reinforcing effects have not been demonstrated.

OBJECTIVE

The primary aims of this study were to examine the reinforcing effects of oral cocaine and determine whether such effects can be influenced by manipulating behavioral requirements following drug ingestion.

METHODS

Nine adult volunteers with histories of cocaine abuse were trained to discriminate between orally administered cocaine (100 mg/70 kg) and placebo capsules under double-blind conditions. Following acquisition of cocaine vs placebo discrimination (80% correct), the reinforcing effects of cocaine were determined using two different choice conditions (dependent and independent). Volunteers were first exposed to cocaine and placebo once each with a relaxation activity (sitting in a cushioned chair) and a vigilance activity (performing a computer task). Following exposure to each drug with each activity, volunteers began the dependent choice condition. Every 2 days volunteers chose which drug (cocaine or placebo) they ingested with the vigilance and relaxation activities. Volunteers could not choose the same drug with both activities. This procedure occurred 5 times over a 10-day period. The independent choice condition took place over 2 days. On one day, volunteers chose which drug (cocaine or placebo) they ingested with the relaxation activity and, on the other day (in counterbalanced order), which drug they ingested with the vigilance activity. Volunteers were allowed to select the same drug with both activities.

RESULTS

All volunteers successfully acquired the cocaine vs placebo discrimination. In the dependent choice condition, all volunteers significantly chose cocaine over placebo with the vigilance activity and chose placebo over cocaine with the relaxation activity. In the independent choice condition, volunteers significantly chose cocaine over placebo with the vigilance activity (i.e., cocaine functioned as a positive reinforcer in the vigilance context). Interestingly, the independent choice condition also showed that volunteers chose placebo over cocaine with the relaxation activity (i.e., cocaine functioned as a negative reinforcer because it was avoided relative to placebo).

CONCLUSION

The study shows that the behavioral requirements following drug ingestion can be a determinant of whether or not oral cocaine functions as a reinforcer in volunteers with histories of cocaine abuse.

The effectiveness of incentives in enhancing treatment attendance and drug abstinence in methadone-maintained pregnant women

This study examined the effectiveness of short-term contingency management for eliminating cocaine use and increasing full day treatment attendance with pregnant methadone-maintained women randomly assigned to either an escalating voucher incentive schedule (n=44) or non-incentive (n=36) conditions. Full day treatment attendance and urine toxicology for cocaine and heroin were assessed and consequated for 14 days. The escalating voucher incentive schedule significantly increased full day treatment attendance and drug abstinence compared to the non-incentive schedule. These results suggest that reinforcing the co-occurrence of two required behaviors (treatment attendance and abstinence from illicit drug use) is effective, and may be an important adjunct to methadone pharmacotherapy for treating pregnant drug dependent women.

[Validation of the use of aequorin for cytoplasmic free calcium determination by chemiluminescence in Streptococcus pneumoniae]

In the extracellular pathogen Streptococcus pneumoniae, transformable by soluble DNA, calcium transport is shown to play a key role for vegetative growth, developement of competence for genetic transformation and experimental virulence. To get a more precise localisation of Ca2+ in the cell, we cloned the cDNA of apoaequorine in the chromosome of Streptococcus pneumoniae. This allowed the reconstitution of the acquorine system and chemoluminescence measurements of the cytoplasmic free calcium concentration in the bacteria. Intracellular free Ca2+ is 2 microM at the steady state and can reach 14 microM when calcium is added to the bacterial suspension. Increase in free Ca2+ in response to an imposed Ca2+ gradient depends on the initial velocity (Vi) of the DMB-sensitive Ca2+ transport, showing that changes in cytoplasmic Ca2+ involve active transport.

Spatial summation in lateral geniculate nucleus and visual cortex

We have compared the spatial summation characteristics of cells in the primary visual cortex with those of cells in the dorsal lateral geniculate nucleus (LGN) that provide the input to the cortex. We explored the influence of varying the diameter of a patch of grating centred over the receptive field and quantitatively determined the optimal summation diameter and the degree of surround suppression for cells at both levels of the visual system using the same stimulus parameters. The mean optimal summation size for LGN cells (0.90 degrees) was much smaller than that of cortical cells (3.58 degrees). Virtually all LGN cells exhibited strong surround suppression with a mean value of 74%+/-1.61% SEM for the population as a whole. This potent surround suppression in the cells providing the input to the cortex suggests that cortical cells must integrate their much larger summation fields from the low firing rates associated with the suppression plateau of the LGN cell responses. Our data suggest that the strongest input to cortical cells will arise from geniculate cells representing areas of visual space located at the borders of a visual stimulus. We suggest that analysis of response properties by patterns centred over the receptive fields of cells may give a misleading impression of the process of the representation. Analysis of pattern terminations or salient borders over the receptive field may provide much more insight into the processing algorithms involved in stimulus representation.

Oscillations and long-lasting correlations in a model of the lateral geniculate nucleus and visual cortex

We have previously developed a model of the corticogeniculate system to explore cortically induced synchronization of lateral geniculate nucleus (LGN) neurons. Our model was based on the experiments of Sillito et al. Recently Brody discovered that the LGN events found by Sillito et al. correlate over a much longer period of time than expected from the stimulus-driven responses and proposed a cortically induced slow covariation in LGN cell membrane potentials to account for this phenomenon. We have examined the data from our model, and we found, to our surprise, that the model shows the same long-term correlation. The model's behavior was the result of a previously unsuspected oscillatory effect, not a slow covariation. The oscillations were in the same frequency range as the well-known spindle oscillations of the thalamocortical system. In the model, the strength of feedback inhibition from the cortex and the presence of low-threshold calcium channels in LGN cells were important. We also found that by making the oscillations more pronounced, we could get a better fit to the experimental data.

Nalmefene: blockade of intravenous morphine challenge effects in opioid abusing humans

No studies have assessed the dose-effect or duration of opioid blockade in opioid abusers produced by oral nalmefene, a micro-opioid antagonist. The present study examined the profile and time course of oral nalmefene blockade of subjective and physiological effects produced by intravenous morphine. To assess these effects, seven opioid abusers received oral nalmefene (0, 50 and 100 mg) followed by intravenous morphine (0, 10 and 20 mg) challenges every 24 h for 96 h using a Latin square randomized cross-over design. The duration of blockade varied by measure and dose. Both 50 and 100 mg nalmefene blocked morphine's effects up to 48 h.

Improving treatment outcomes for pregnant drug-dependent women using low-magnitude voucher incentives

The aim of this study was to examine the effectiveness of low-magnitude behavioral incentives in improving attendance for abstinence-treated patients and sustaining illicit-drug abstinence for methadone-treated patients. Subjects were randomly assigned to either incentive or control conditions, with target behaviors differing for the two patient groups (attendance for abstinence-treated and abstinence for methadone-treated patients). Controls received no incentives, whereas incentive subjects could earn $5/day in vouchers during the first 7 days of an intensive outpatient treatment. Results showed that $5/day did not significantly improve attendance in abstinence-treated patients or impact drug abstinence in methadone-treated patients. The data suggest that low-magnitude voucher incentives enhanced treatment attendance by methadone-treated subjects. Although modest monetary incentives had some utility in improving attendance in methadone-treated patients, more potent interventions are needed to improve attendance and maintain abstinence in this high-risk population.

Caffeine withdrawal increases cerebral blood flow velocity and alters quantitative electroencephalography (EEG) activity

RATIONALE

Cessation of daily caffeine consumption produces a withdrawal syndrome comprised of subjective symptoms and functional impairment. Few controlled studies have examined the physiological effects of caffeine withdrawal.

OBJECTIVE

The present study examined the effect of caffeine withdrawal on cerebral blood flow velocity and quantitative EEG.

METHODS

Ten volunteers reporting moderate caffeine intake (mean 333 mg/day) participated in this double-blind study. Subjects completed several tests when maintaining their normal diet (baseline period) and during two 1-day periods during which they consumed caffeine-free diets and received capsules containing placebo (placebo test session) or caffeine (caffeine test session) in amounts equal to their baseline daily caffeine consumption. Blood flow velocity was determined for four arteries: right and left middle (MCA), and right and left anterior (ACA) cerebral arteries using pulsed transcranial Doppler sonography. EEG was recorded for 3 min from eight scalp sites while subjects sat, with eyes closed, in a sound-attenuated electronically shielded chamber. Subjective effects were assessed with questionnaires.

RESULTS

Results showed an effect of the placebo (21-h withdrawal) condition compared to the caffeine condition. Placebo significantly increased the mean velocity, systolic velocity and diastolic velocity (cm/s) in all four cerebral arteries. In the MCA, the pulsatility index was significantly decreased following placebo. Placebo significantly increased EEG theta power. Placebo also produces subjective effect changes, including increases in heavy feelings in arms and legs and decreases in ability to concentrate. The caffeine and baseline conditions produced similar results on both the physiological and subjective measures.

CONCLUSION

Cessation of daily caffeine consumption produced changes in cerebral blood flow velocity and quantitative EEG. These changes may be related to classic caffeine withdrawal symptoms of headache, drowsiness and decreased alertness.

An assessment of the role of intracellular free Ca2+ in E. coli

We have previously proposed that fluctuations in Ca(2+) levels should play an important role in bacteria as in eukaryotes in regulating cell cycle events (Norris et al., J. Theor. Biol. 134 (1998) 341-350). This proposal implied the presence of Ca(2+) uptake systems in bacteria, cell cycle mutants simultaneously defective in Ca(2+)-homeostasis, and perturbation of cell cycle processes when cellular Ca(2+) levels are depleted. We review the properties of new cell cycle mutants in E. coli and B. subtilis resistant to inhibitors of calmodulin, PKC or Ca(2+)-channels; the evidence for Ca(2+)-binding proteins including Acp and FtsZ; and Ca(2+)-transporters. In addition, the effects of EGTA and verapamil (a Ca(2+) channel inhibitor) on growth, protein synthesis and cell cycle events in E. coli are described. We also describe new measurements of free Ca(2+)-levels, using aequorin, in E. coli. Several new cell cycle mutants were obtained using this approach, affecting either initiation of DNA replication or in particular cell division at non-permissive temperature. Several of the mutants were also hypersensitive to EGTA and or Ca(2+). However, none of the mutants apparently involved direct alteration of a drug target and surprisingly in some cases involved specific tRNAs or a tRNA synthetase. The results also indicate that the expression of several genes in E. coli may be regulated by Ca(2+). Cell division in particular appears very sensitive to the level of cell Ca(2+), with the frequency of division clearly reduced by EGTA and by verapamil. However, whilst the effect of EGTA was clearly correlated with depletion of cellular Ca(2+) including free Ca(2+), this was not the case with verapamil which appears to change membrane fluidity and the consequent activity of membrane proteins. Measurement of free Ca(2+) in living cells indicated levels of 200-300 nM, tightly regulated in wild type cells in exponential phase, somewhat less so in stationary phase, with apparently La(2+)-sensitive PHB-polyphosphate complexes involved in Ca(2+) influx. The evidence reviewed increasingly supports a role for Ca(2+) in cellular processes in bacteria, however, any direct link to the control of cell cycle events remains to be established.

Assessment of opioid partial agonist activity with a three-choice hydromorphone dose-discrimination procedure

The discriminative stimulus and subjective effects of opioid mixed agonist-antagonists were assessed in volunteer nondependent heroin users trained in a three-choice drug discrimination procedure to discriminate among the effects of i.m. administration of 2 ml of saline, 1 mg of hydromorphone, and 4 mg of hydromorphone (a morphine-like mu agonist). Other subjective, behavioral, and physiological measures were concurrently collected. The discrimination was readily learned by six of the eight subjects. After training, generalization curves were determined for the following i.m. drug conditions: hydromorphone (0.375-4.0 mg), pentazocine (7.5-60 mg), butorphanol (0.75-6 mg), nalbuphine (3-24 mg), and buprenorphine (0.075-0.6 mg). All five of the test drugs were discriminated significantly or showed trends toward being discriminated as hydromorphone 1 mg-like at one or more dose levels. Hydromorphone showed an inverted U-shaped dose-effect function on the hydromorphone 1 mg-like discrimination. Subjective effect measures produced clearer differentiation among the test drugs than did drug discrimination performance. The present results differ from those of a previous study that observed a close relationship between the results of the discrimination measure and subjective effect measures. The previous study used similar methods and test drugs but different training drugs (e.g., 3 mg of hydromorphone versus 6 mg of butorphanol versus saline). It appears that both the sensitivity of drug discrimination performance to between-drug differences and the relationship between discriminative and subjective effects depends upon the specific discrimination that is trained (e.g., two-choice or three-choice). The present high dose-low dose-saline discrimination procedure appears useful for assessing partial agonist activity. The present data are consistent with partial agonist activity for pentazocine, butorphanol, nalbuphine, and buprenorphine.

Phencyclidine- and diazepam-like discriminative stimulus effects of inhalants in mice

It has been shown that abused solvents, such as 1,1,1-trichloroethane (TCE) and toluene, share certain pharmacological properties with central nervous system depressants, such as alcohol and anesthetic vapors. Several vapors were tested for diazepam (DZ)- and phencyclidine (PCP)-like discriminative stimulus effects to further explore their pharmacological specificity. In DZ-trained mice, methoxyflurane fully substituted, and TCE produced partial substitution. Fluorothyl and toluene produced no appreciable DZ-lever responding at any concentration tested. On the other hand, toluene produced concentration-related partial substitution for PCP, whereas methoxyflurane, TCE, and fluorothyl did not substitute. The substitution of some these vapors for DZ or PCP suggests that, like ethanol, the discriminative stimulus effects of abused solvents partially overlap those of N-methyl-D-aspartate antagonists as well as those of gamma amino butyric acid agonists.

Slow changes in cytosolic free Ca2+ in Escherichia coli highlight two putative influx mechanisms in response to changes in extracellular calcium

Free intracellular Ca2+ ([Ca2+]i) in Escherichia coli was measured using the bioluminescent protein aequorin. Overall, the bacteria maintained a tight control on their free [Ca2+]i. The results indicated a slow Ca2+ influx, the magnitude of the initial rise in free [Ca2+]i being dependent upon the concentrations of external Ca2+. This was followed by the slow removal of free Ca2+ until normal levels were restored. Specifically, addition of external Ca2+ (0.25-10 mM) resulted in a gradual rise in intracellular free Ca2+ from a basal level of approximately 272 nM, maximally reaching a peak of 0.85-5.4 microM within 30-40 min. This was followed by a slow fall over the next 30 min, culminating in an oscillatory pattern of free [Ca2+]i (range 0.3-0.7 microM for 0.25 mM external Ca2+). In the presence of EGTA, free [Ca2+]i was dramatically reduced. Neither the influx of Ca2+ nor restoration of intracellular free Ca2+ required protein synthesis. Moreover, preincubation with Ca2+ increased the rising phase of intracellular Ca2+ in response to further exposure to external Ca2+. This was further evidence against a specific adaptation process such as the synthesis of calcium exporters. A putative Ca2+ influx channel was demonstrated in stationary phase cells in particular, which could be blocked by La3+. This channel was consistent with the voltage-activated poly-3-hydroxybutyrate/polyphosphate Ca2+ channels previously detailed by Reusch et al. [23] Even in the presence of La3+, however, the free [Ca2+]i of log phase and stationary phase bacteria still increased two-fold over resting values in response to external Ca2+. This suggested the presence of at least two Ca2+ influx processes, one inhibited by La3+ and the other not.

Phencyclidine- and diazepam-like discriminative stimulus effects of inhalants in mice

It has been shown that abused solvents, such as 1,1,1-trichloroethane (TCE) and toluene, share certain pharmacological properties with central nervous system depressants, such as alcohol and anesthetic vapors. Several vapors were tested for diazepam (DZ)- and phencyclidine (PCP)-like discriminative stimulus effects to further explore their pharmacological specificity. In DZ-trained mice, methoxyflurane fully substituted, and TCE produced partial substitution. Fluorothyl and toluene produced no appreciable DZ-lever responding at any concentration tested. On the other hand, toluene produced concentration-related partial substitution for PCP, whereas methoxyflurane, TCE, and fluorothyl did not substitute. The substitution of some these vapors for DZ or PCP suggests that, like ethanol, the discriminative stimulus effects of abused solvents partially overlap those of N-methyl-D-aspartate antagonists as well as those of gamma amino butyric acid agonists.

Subjective and physiological effects of intravenous nicotine and cocaine in cigarette smoking cocaine abusers

The subjective and physiological effects of intravenously administered cocaine and nicotine were compared in 10 cigarette-smoking cocaine abusers. Subjects abstained from smoking at least 8 h before each session. Under double blind conditions, subjects received placebo, cocaine (10, 20, and 40 mg/70 mg), or nicotine (0.75, 1.5, 3.0 mg/70 kg) in mixed order. Physiological and subjective data were collected before and repeatedly after each intravenous drug administration. Subjects also completed a drug versus money multiple-choice procedure in which they chose between that day's drug and 44 monetary values. Both drugs increased blood pressure and heart rate and decreased skin temperature. Nicotine showed a more rapid onset of subjective effects than cocaine. Overall, although both cocaine and nicotine increased subjective ratings of "drug effect", "rush", "good effects", "liking", "high", and "stimulated", only nicotine increased ratings of "bad effects" and "jittery". Although the highest nicotine dose produced greater effects than the highest cocaine dose on most subjective measures, the highest cocaine dose produced somewhat greater ratings of drug liking. At doses that produced comparable ratings of drug effect (40 mg/70 kg cocaine versus 1.5 mg/70 kg nicotine), cocaine produced significantly greater good effects, whereas nicotine produced greater bad effects. All three cocaine doses and the intermediate and high nicotine doses were frequently categorized as producing effects similar to those of cocaine or amphetamine. The drug versus money measure showed that the highest cocaine dose was worth twice as much as the highest nicotine dose. Thus, intravenous cocaine and nicotine can be differentiated by their subjective and reinforcing effects.

Induction with levomethadyl acetate: safety and efficacy

BACKGROUND

Levomethadyl acetate hydrochloride (known as LAAM) is a mu-opioid agonist approved for the treatment of opioid dependence. Clinical trials comparing LAAM and methadone have reported lower patient retention rates during LAAM induction; however, this may reflect dose and schedule differences. Few studies have systematically examined LAAM dose induction. This study compared induction with 3 different LAAM dosage levels.

METHODS

In a randomized, double-blind trial, male and female opioid-dependent patients (N = 180) were assigned to 1 of 3 LAAM doses. The low-dose (25 mg) induction was constant from the onset of treatment, the medium-dose (50 mg) induction lasted 7 days, and the high-dose (100 mg) induction lasted 17 days. Safety and efficacy were assessed on retention, urinalysis and self-reported drug use, symptoms, and patient ratings of medication adequacy.

RESULTS

The high-dose group had significantly fewer illicit opioid-positive urine samples in weeks 3 and 4 as compared with the low-dose group. The high-dose group had significantly lower self-reported heroin craving in weeks 2 and 3. All groups demonstrated significant decreases in illicit drug use, withdrawal symptoms, and depression. There were no between-group differences in retention; however, there was a trend (P = .08) for lower retention and a greater number of agonist adverse effects were observed in the high-dose group. Overall, LAAM doses were well tolerated by most patients.

CONCLUSION

Induction with low and medium LAAM doses can be safely and effectively achieved within 7 days. Induction with higher LAAM doses can be safely achieved within 17 days, but may result in greater rates of patient dropout and opioid agonist adverse effects. Therefore, higher doses should be approached more slowly.

Evaluation of the reinforcing and discriminative stimulus properties of the low-affinity N-methyl-D-aspartate channel blocker memantine

Memantine (MEM) is currently in clinical use in Europe for the treatment of various neurological disorders. It is a low-affinity channel blocker of N-methyl-D-aspartate (NMDA) receptors whose voltage-dependent, rapid binding kinetics are believed to limit its phencyclidine (PCP)-like side effects. MEM, and its analog amantadine (AMA), which has also been demonstrated to have some NMDA antagonist activity, were evaluated for PCP-like behavioral effects. The discriminative stimulus properties of MEM and AMA were tested in monkeys and rats trained to discriminate PCP from saline using a standard two-lever drug discrimination paradigm under a fixed ratio (FR) schedule of food reinforcement. In rats, MEM resulted in a dose-dependent substitution for PCP; however, full substitution occurred only at response rate suppressing doses. AMA failed to substitute for PCP at any dose tested. For MEM, all four monkeys showed complete substitution for PCP at doses which did not greatly decrease rates of responding. Conversely, AMA occasioned little or no responding on the PCP-associated level in any of the subjects. Intravenous self-administration of MEM and AMA was tested under a FR schedule of reinforcement in four monkeys trained to lever press for infusions of PCP. MEM served as a reinforcer in all subjects at one or more doses tested. For two of the subjects, at least one dose of AMA maintained rates of self-administration above those for saline. For both MEM and AMA, maximal response rates were considerably lower than with PCP self-administration and both drugs were much less potent in monkeys than would be predicted from rodent studies. The data show that MEM shares discriminative stimulus effects with PCP under these testing conditions, whereas the chemically similar compound AMA does not. MEM also serves as a positive reinforcer in rhesus monkeys, whereas AMA can serve as a weak reinforcer in only some subjects. Both AMA and MEM are reported to function as NMDA antagonists, yet clear differences exist in their behavioral effects with MEM acting more like a PCP-like antagonist. In addition, despite the rapid channel kinetics of MEM's NMDA receptor blockade, it may have some PCP-like abuse potential in humans at doses above the normal therapeutic levels.

Inhalant abuse in pregnancy

Information from a variety of sources suggests the possibility of adverse effects of maternal inhalant abuse, although a well-controlled, prospective study in this area has not been conducted. One source of this concern is the data from occupational exposure to some of the abused solvents, specifically toluene and TCE, with numerous reports suggesting increased spontaneous abortion and fetal malformations. There are also data suggesting decreased fertility and an increased risk for spontaneous abortion in health care workers exposed to nitrous oxide. The relevance of these studies to problems of inhalant abuse is not clear. Although the chemicals involved are the same, there are many differences in the exposure parameters, the populations exposed, and the types of associated risk factors. Nonetheless, there are more than 100 cases reported in the literature of children born to solvent-abusing mothers. Many of these children were small at birth, and some have craniofacial abnormalities not unlike that seen in children with FAS. In the few studies reporting the findings of follow-up in these children, some evidence has been obtained for retardation in growth and development and for residual deficits in cognitive, speech, and motor skills. Clearly, more research is needed to rule out the concomitant risk factors and to identify specific chemicals and patterns of use associated with adverse effects. Animal studies provide more direct evidence that prenatal exposure to toluene or TCE can produce reduced birth weights, occasional skeletal abnormalities, and delayed neurobehavioral development, even under conditions designed to mimic inhalant abuse patterns. Additional research is needed to identify other chemicals with adverse effects, critical periods of exposure, effects of combinations of inhalants, or interactions with drugs of abuse. The research literature seems sufficient to alert clinicians to possible problems in patients who abuse inhalants while pregnant. Diagnosis and good prenatal care for these women are important. The evidence for neonatal withdrawal is limited at this time; however, infants born to women who have recently used inhalants should be observed carefully for an alcohol-like withdrawal syndrome. Although it is not possible to link a specific birth defect or developmental problem in the child of an inhalant abuser to prenatal exposure to a specific chemical, it is clear that inhalant abuse and its associated lifestyle place children at increased risk. A wider appreciation of this is needed among health care professionals and the general public.

Muscimol-like discriminative stimulus effects of GABA agonists in rats

The discriminative stimulus effects of GABAergic drugs were evaluated in rats trained to discriminate the direct GABA(A) agonist, muscimol (1.0 mg/kg I.P.), from saline under a two-lever fixed ratio (FR) 32 schedule of food reinforcement. Another direct GABA(A) agonist, THIP, produced full substitution for muscimol, however, at doses producing response rate decreasing effects. Diazepam, an allosteric modulator of GABA-mediated postsynaptic inhibition, yielded a maximum of 50% muscimol-lever responding at a dose that also decreased rates of responding. Partial substitution for muscimol (maximal levels of 71% muscimol-lever responding) was also produced by the GABA agonist progabide. Propofol, an anesthetic that potentiates GABA(A) receptor function, and the GABA uptake inhibitor, tiagabine, produced no greater than 53 and 48% muscimol-lever responding, respectively. Valproic acid, a reversible GABA transaminase inhibitor, failed to substitute for muscimol, and vigabatrin, an irreversible GABA transaminase inhibitor, yielded a maximal 46% muscimol-lever responding. These results demonstrate the pharmacological specificity of muscimol discrimination by showing that only direct agonists for the GABA site on the GABA(A) receptor complex produce full substitution. GABA agonists acting by other mechanisms can be distinguished from muscimol and THIP in this procedure.

Failure of ibogaine to produce phencyclidine-like discriminative stimulus effects in rats and monkeys

The discriminative stimulus properties of ibogaine were investigated in rats trained to discriminate phencyclidine (PCP; 2.0 mg/kg, I.P.) from saline under a two-lever fixed-ratio (FR) 32 schedule of food reinforcement. Ibogaine (5.6-17.6 mg/kg, I.P.) showed a complete lack of substitution. Ibogaine (0.5-4.0 mg/kg, I.M.) also failed to generalize in rhesus monkeys trained to discriminate PCP (0.1 mg/kg, I.M.) from sham injection. Lysergic acid diethylamide (LSD), tested as a reference compound, produced partial substitution for PCP in rats and occasioned little responding on the PCP-associated lever in monkeys. These results demonstrate important differences between the behavioral effects of PCP and other types of hallucinogenic drugs such as LSD and ibogaine and do not support the hypothesis that the affinity of ibogaine for the PCP site on N-methyl-D-aspartate (NMDA) receptors plays a major role in its acute behavioral effects.

Oral terbinafine in the treatment of toenail onychomycosis: North American multicenter trial

BACKGROUND

Onychomycosis is an increasing problem with limited therapeutic options.

OBJECTIVE

We evaluated the safety and efficacy, of oral terbinafine, a new fungicidal antimycotic, in patients with toenail onychomycosis.

METHODS

A North American multicenter, double-blind, placebo-controlled study evaluated the mycologic and clinical efficacy of oral terbinafine 250 mg/day for 12 or 24 weeks in 358 patients with toenail onychomycosis.

RESULTS

A total of 74% of patients treated with 12 or 24 weeks of terbinafine achieved a successful clinical outcome. Approximately 11% of terbinafine responders showed evidence of relapse 18 of 21 months after cessation of treatment. Terbinafine was well tolerated; most adverse events were transient and mild to moderate in severity.

CONCLUSION

The results of this study confirm that oral terbinafine is a safe and effective therapy for the treatment of onychomycosis.

Evaluation of the reinforcing and discriminative stimulus effects of the N-methyl-D-aspartate competitive antagonist NPC 17742 in rhesus monkeys

The phencyclidine (PCP)-like effects of the N-methyl-D-aspartate (NMDA) competitive antagonist 2R,4R,5S-2-amino-4,5-(1,2-cyclohexyl)-7-phosphonoheptanoic acid (NPC 17742) were evaluated in three behavioral tests in rhesus monkeys. The discriminative stimulus properties of NPC 17742 (2-24 mg/kg, i.m.) were tested in four rhesus monkeys trained to discriminate PCP from saline under a fixed-ratio (FR) 50 schedule of food reinforcement. In three of the monkeys, NPC 17742 showed complete substitution for PCP at doses which did not decrease rates of responding. Intravenous self-administration of NPC 17742 (50-800 micrograms/kg/infusion) was tested under a FR schedule of reinforcement in four monkeys trained to lever press for infusions of PCP. At least one dose of NPC 17742 functioned as a reinforcer in two of the monkeys. A second self-administration study, employing a 10 min fixed interval schedule of reinforcement, was performed in three monkeys trained to self-administer PCP during three daily sessions. Compared with PCP, NPC 17742 (0.4-1.6 mg/kg/infusion) maintained very low rates of responding; NPC 17742 could not be clearly established as a reinforcer in this procedure. The data show that NPC 17742 has some PCP-like behavioral effects, and may function as a weak reinforcer in some subjects under specific conditions. The results provide further evidence that both similarities and differences exist between the behavioral effects of PCP and competitive NMDA antagonists.

Past and present levels of some radionuclides in fish from Bikini and Enewetak Atolls

Bikini and Enewetak were the sites in the Northern Marshall Islands that were used by the United States as testing grounds for nuclear devices between 1946 and 1958. The testing produced close-in fallout debris that was contaminated with different radionuclides and which entered the aquatic environment. The contaminated lagoon sediments became a reservoir and source term of manmade radionuclides for the resident marine organisms. This report contains a summary of all the available data on the concentrations of 137Cs, 60Co and 207Bi in flesh samples of reef and pelagic fish collected from Bikini and Enewetak Atolls between 1964 and 1995. The selection of these three radionuclides for discussion is based on the fact that these are the only radionuclides that have been routinely detected by gamma spectrometry in flesh samples from all fish for the last 20 y. Flesh from fish is an important source of food in the Marshallese diet. These radionuclides along with the transuranic radionuclides and 90Sr contribute most of the small radiological dose from ingesting marine foods. Some basic relationships among concentrations in different tissues and organs are discussed. The reef fish can be used as indicator species because their body burden is derived from feeding, over a lifetime, within a relatively small contaminated area of the lagoon. Therefore, the emphasis of this report is to use this extensive and unique concentration data base to describe the effective half lives and cycling for the radionuclides in the marine environments during the 31-y period between 1964 and 1995. The results from an analysis of the radionuclide concentrations in the flesh samples indicate the removal rates for the 3 radionuclides are significantly different. 137Cs is removed from the lagoons with an effective half life of 9-12 y. Little 60Co is mobilized to the water column so that it is depleted in both environments, primarily through radioactive decay. The properties of 207Bi are different at Enewetak and Bikini. At Enewetak the radionuclide is lost from the environment with an effective half live of 5.1 y. At Bikini only radioactive decay can account for the rate at which the radionuclide is lost from the lagoon. The difference in the binding properties of the sedimentary materials for 207Bi among the two Atolls is not understood.

Neurobehavioral consequences of intermittent prenatal exposure to high concentrations of toluene

The effects of several concentrations of toluene on physical and behavioral development were examined in CD-1 mice prenatally exposed during the last week of gestation. Pregnant mice were exposed to either 200, 400, or 2000 ppm toluene (TOL) for 60 min three times a day during gestational days 12-17. A sham group was exposed concurrently to filtered air. No group differences were observed in maternal weight gain or food consumption, common measures of maternal toxicity. Initial litter characteristics including gestation length, number of litters delivered, and litter size were also similar. At birth, mean initial individual pup weight from representative male and female 2000 TOL-exposed pups was less than sham-exposed pups; however, entire litter weight did not differ. Pups were evaluated on postnatal days 1-20. Pups exposed to 2000 TOL gained less weight and performed more poorly on the behavioral tests of the righting reflex, grip strength, and inverted screen. In contrast, pups exposed to either 200 or 400 TOL did not differ from sham-exposed pups on any of the measures of development or behavior. These data provide evidence for the neurobehavioral teratogenicity of prenatal exposure to high levels of toluene late in gestation. Because this exposure regimen of intermittent high-concentration exposure was designed to simulate human exposures that might occur with toluene abuse, these results are consistent with case reports of adverse consequences of inhalant abuse by pregnant women.

New EGF-R selective tyrosine kinase inhibitor reveals variable growth responses in prostate carcinoma cell lines PC-3 and DU-145

The effect of an EGF-R selective tyrosine kinase inhibitor ZM252868 was evaluated on the proliferation of PC-3 and DU-145 prostate cancer cell lines, which are purported to utilize an EGF-R-mediated autocrine pathway for regulation of cell growth. Basal growth of DU-145 cells was inhibited in a dose-dependent manner by the inhibitor, showing a 70% reduction at 1 microM, whilst the growth of PC-3 cells was not affected at this concentration. In the presence of 0.1 microM inhibitor, EGF and TGF alpha-stimulated DU-145 cell growth was decreased to below basal levels, while only TGF alpha-stimulated PC-3 cell growth was inhibited at a 1-microM concentration. Any growth responses to aFGF, bFGF, KGF, IGF1 and PDGF by DU-145 and PC-3 cells were unaffected by the inhibitor at concentrations of 1 microM or less. Additionally, the distribution of immunoreactive EGF-R varied between DU-145 and PC-3 cells, with EGF-R being predominately located on the cell membrane and in the cytoplasm, respectively.

Effect of n-6 polyunsaturated fatty acids on growth and lipid composition of neoplastic and non-neoplastic canine prostate epithelial cell cultures

BACKGROUND

Polyunsaturated fatty acids (n-6) are reported to selectively kill malignant cells. Most investigations, however, did not compare neoplastic with non-neoplastic cells from the same tissue type. Here we evaluate the effects of n-6 fatty acids on a non-neoplastic epithelium cell line (CAPE) and a spontaneous carcinoma cell line (CPA) derived from the canine prostate.

METHODS

Cell lines were cultured in DME in the presence of fatty acids and their effects on cell proliferation monitored by coulter counting. Lipids were extracted and quantitized by gas chromatography.

RESULTS

Cell proliferation was reduced more in CAPE. A neoplastic strain (CPA-GLA) tolerant to prolonged culture in 18:3n-6 was isolated. CPA grown in an 18:2n-6 or 18:3n-6 supplemented media accumulated 20:3n-6 and contained little 20:4n-6.

CONCLUSIONS

Polyenoic n-6 fatty acids are not specifically inhibitory to neoplastic cells which exhibited a marked alteration in the metabolism of 20:4n-6.

Double-blind, randomized comparison of itraconazole capsules vs. placebo in the treatment of toenail onychomycosis

Three multicenter, randomized, double-blind, placebo-controlled studies were conducted to determine whether twelve weeks of therapy with itraconazole, 200 mg, was effective in the treatment of dermatophyte infection of the toenail. Significantly more patients treated with itraconazole (110 patients) than with placebo (104 patients) achieved clinical (65 percent vs. 3 percent) and mycologic (54 percent vs. 6 percent) success. The mean percentage of affected reference nail before the initiation of therapy was 76 percent. Adverse events were comparable in the two treatment groups. These findings demonstrate that twelve weeks of continuous itraconazole, 200 mg once daily, is a highly effective, well-tolerated therapy for the management of toenail onychomycosis.

Comparative studies of the mitogenic effects of epidermal growth factor and transforming growth factor-alpha and the expression of various growth factors in neoplastic and non-neoplastic prostatic cell lines

BACKGROUND

The role of growth factors in prostate cell growth has been investigated as these peptides may be involved in the autonomous growth of hormone-independent prostate cancer.

METHODS

Responses of neoplastic (PC-3 and CPA) and non-neoplastic (CAPE) prostatic cell lines to epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) were determined using clonogenic and growth curve analysis. The constitutive expression of EGF, TGF-alpha, and TGF-beta 1-3 mRNA was examined using Northern blotting and EGF and TGF-alpha protein levels were determined immunohistochemically.

RESULTS

Growth curve and clonogenic analysis indicated that EGF and TGF-alpha were mitogenic in each cell line. The magnitude of the clonogenic response varied between the cell lines, with CPA cells showing the greatest growth increases. CPA cells also displayed the highest levels of EGF and TGF-alpha mRNA and protein. TGF-beta 1 mRNA was detected in the order of magnitude, PC-3 > CPA > CAPE. Furthermore, PC-3 and CPA cells expressed TGF-beta 3 and TGF-beta 2 transcripts respectively. In each cell line, the expression of any growth factor mRNA was not affected by exogenous EGF.

CONCLUSIONS

The growth responses of the cell lines to EGF and TGF-alpha did not correlate with their constitutive levels of EGF and TGF-alpha mRNA and protein, thus whilst growth factors may be important in malignant cell growth, other pathways may also be involved in the autocrine regulation of cell proliferation.

Response of cell growth and retinoic acid receptor expression to retinoic acid in neoplastic and non-neoplastic prostate cell lines

BACKGROUND

Retinoic acid (RA) is recognized as an inhibitor of tumorigenesis, but conversely, has also been shown to act as a tumor enhancer, therefore its role in prostate tumor cell growth was investigated.

METHODS

The response of two human prostate tumor cell lines (PC-3 and DU-145), and cell lines derived from a well-differentiated canine prostate adenocarcinoma (CPA) and normal canine prostate epithelium (CAPE) to all-trans RA was determined using growth curve analysis. Additionally, the constitutive expression and RA-challenged expression of retinoic acid receptors (RARs) -alpha, -beta, and -gamma mRNA was examined using Northern blotting techniques.

RESULTS

In response to all-trans RA, the PC-3 and DU-145 cell lines showed considerable growth promotion, while CAPE and CPA cell growth was dramatically inhibited. Each cell line expressed RAR alpha and RAR gamma, with either negligible or no RAR beta transcripts being detected. RAR alpha and -gamma mRNAs detected in the four cell lines were variably regulated in response to RA, and no distinct patterns of RAR regulation that could be related to cell growth responses were observed.

CONCLUSIONS

The data indicates that no simple association exists between the expression or regulation of RAR subtype mRNAs and the divergent growth responses to RA displayed by the prostate cell lines.

Prenatal stress alters the size of the rostral anterior commissure in rats

In rodents and other mammals, prenatal stress disrupts both sexual differentiation and sexual behavior. The present study examined the area of the anterior division of the anterior commissure (the Aca) in coronal, thionin-stained sections of prenatally stressed (P-S), and control male and female rats. Pregnant rats were exposed to thrice-daily heat, light, and restraint stress or left undisturbed during days 15-22 of pregnancy. Adult P-S and control males and females were killed, perfused, and their brains removed. Serial coronal sections (total of approximately 200 microm) through the rostral portion of the Aca (the rAca) were taken and stained with thionin. The sections were examined and traced under x25 using computerized microscopy to obtain the area in mm2. The data revealed that control females had a larger rAca compared to control males, and that P-S males had a larger rAca compared to control males; further, control males and P-S females were not significantly different, nor were control females and P-S males. These results suggest that, in rats, the Ac may be sexually dimorphic (in a direction similar to that described in humans) and that prenatal stress an event that modifies sex-typical behavior, physiology, and neuroanatomy reverses that sex difference.

Developmental consequences of intermittent and continuous prenatal exposure to 1,1,1-trichloroethane in mice

The effects of 1,1,1-trichloroethane (TCE) on physical and behavioral development were examined in CD-1 mice prenatally exposed under two regimens. In the first study, pregnant mice were exposed to either 2,000 ppm TCE or filtered air for 17 hrs. during gestational days (GD) 12-17. A third group remained untreated. The results revealed no differences on pregnancy outcome. TCE-exposed pups gained less weight, exhibited delays in developmental landmarks and acquisition of the righting reflex, had poorer performance on tests of motor coordination and exhibited delays in negative geotaxis relative to sham or untreated pups. A second experiment was designed to more closely parallel the intermittent, acute, high-concentration pattern of solvent abuse. Pregnant mice were exposed for 60 min. to 8,000 ppm TCE or sham placement in exposure chambers three times/day during GD's 12-17. The results were very similar to what were obtained in the more continuous exposure study. TCE-exposed pups gained less weight, had delays in developmental landmarks and acquisition of the righting reflex and exhibited weaker grip strength, poorer negative geotaxis and less rooting intensity in comparison to sham pups. These data provide evidence for the behavioral and developmental teratogenicity of prenatal TCE exposure late in gestation.