Separation of cashew (Anacardium occidentale L.) nut shell liquid with supercritical carbon dioxide

Cashew nut shell liquid (CNSL) represents the largest readily available bioresource of alkenyl phenolic compounds. In this work, separation of CNSL from the pericarp of the cashew nut with supercritical carbon dioxide was studied. In the initial extractions with CO(2) at 40-60 degrees C and at pressures from 14.7 to 29.4 MPa, low yields were obtained. However, when the extractions were performed with one or more intermediate depressurization steps, the yield of CNSL increased to as high as 94%. Most of the oil did not separate from the shell during the depressurization step, but was obtained during the subsequent repressurization. The CNSL extract had a clear light brownish pink color and exhibited no evidence of polymerization or degradation. The pressure profile extraction method proposed in this work increases the possible CNSL extraction yields and greatly reduces the amount of CO(2) required for CNSL separation.

Applicability of tetrazolium salts for the measurement of respiratory activity and viability of groundwater bacteria

A study was undertaken to measure aerobic respiration by indigenous bacteria in a sand and gravel aquifer on western Cape Cod, MA using tetrazolium salts and by direct oxygen consumption using gas chromatography (GC). In groundwater and aquifer slurries, the rate of aerobic respiration calculated from the direct GC assay was more than 600 times greater than that using the tetrazolium salt 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl tetrazolium chloride (INT). To explain this discrepancy, the toxicity of INT and two additional tetrazolium salts, sodium 3'-[1-(phenylamino)-carbonyl]-3,4-tetrazolium]-bis(4-methoxy-6-nitro) benzenesulfonic acid hydrate (XTT) and 5-cyano-2,3-ditolyl tetrazolium chloride (CTC), to bacterial isolates from the aquifer was investigated. Each of the three tetrazolium salts was observed to be toxic to some of the groundwater isolates at concentrations normally used in electron transport system (ETS) and viability assays. For example, incubation of cells with XTT (3 mM) caused the density of four of the five groundwater strains tested to decline by more than four orders of magnitude. A reasonable percentage (>57%) of cells killed by CTC and INT contained visible formazan crystals (the insoluble, reduced form of the salts) after 4 h of incubation. Thus, many of the cells reduced enough CTC or INT prior to dying to be considered viable by microscopic evaluation. However, one bacterium (Pseudomonas fluorescens) that remained viable and culturable in the presence of INT and CTC, did not incorporate formazan crystals into more than a few percent of cells, even after 24 h of incubation. This strain would be considered nonviable based on traditional tetrazolium salt reduction assays. The data show that tetrazolium salt assays are likely to dramatically underestimate total ETS activity in groundwater and, although they may provide a reasonable overall estimate of viable cell numbers in a community of groundwater bacteria, some specific strains may be falsely considered nonviable by this assay due to poor uptake or reduction of the salts.

Changing socioeconomic risk factors for invasive H. influenzae disease after the introduction of conjugate vaccine

OBJECTIVES

To determine socioeconomic risk factors for invasive Haemophilus influenzae (HI) disease before and after the introduction of HI type b (Hib) conjugate vaccine in the West Midlands, UK.

METHODS

Study population consisted of children aged <5 years with laboratory confirmed invasive disease. Linear associations between disease rates and socioeconomic variables were examined 2-years before and 2-years after the introduction of conjugate vaccine.

RESULTS

Pre-vaccine there were no trends in disease incidence. Post-vaccine there was an absolute reduction in disease incidence and significant disease differentials between affluent and deprived populations were identified for non-owner-occupancy (P=0.032) and car access (P=0.049).

CONCLUSIONS

Our results suggest that changes in socioeconomic risk factor for invasive HI occurred after the introduction of conjugate vaccine. This may have implications for future immunisation strategies.

Hospital-Acquired Infections in the Surgical Intensive Care: Epidemiology and Prevention

Hospital-acquired infections affect 7% to 10% of hospitalized patients and account for approximately 80,000 deaths per year in the United States. Of all infections acquired in the hospital, more than 20% occur in intensive care unit patients. As the number of ICU beds increases, the proportion of ICU infections is likely to increase. The focus of this paper is to review the epidemiology of hospital-acquired infections that occur in the surgical ICU, particularly ventilator associated pneumonia, catheter-associated urinary tract infection, and catheter-related bloodstream infection, and to discuss ICU-related prevention strategies. By implementing effective preventative measures and maintaining strict surveillance of ICU infections, we hope to affect the associated morbidity, mortality, and cost that our patients and society bare.

Trimethylamine and odorous sweat

Analysis of sweat collected from patients experiencing ichthyohidriosis, and from volunteers in whom this odour phenomenon had been artificially induced, showed that trimethylamine was the major causative factor.

Disposition and metabolism of isoeugenol in the male Fischer 344 rat

The primary objective of these studies was to determine the absorption, distribution, metabolism and excretion of isoeugenol following oral and intravenous administration to male Fischer-344 rats. Following a single oral dose of [14C]isoeugenol (156 mg/kg, 50 microCi/kg), greater than 85% of the administered dose was excreted in the urine predominantly as sulfate or glucuronide metabolites by 72 h. Approximately 10% was recovered in the feces, and less than 0.1% was recovered as CO(2) or expired organics. No parent isoeugenol was detected in the blood at any of the time points analyzed. Following iv administration (15.6 mg/kg, 100 microCi/kg), isoeugenol disappeared rapidly from the blood. The t(1/2) was 12 min and the Cl(s) was 1.9 l/min/kg. Excretion characteristics were similar to those of oral administration. The total amount of radioactivity remaining in selected tissues by 72 h was less than 0.25% of the dose following either oral or intravenous administration. Results of these studies show that isoeugenol is rapidly metabolized and is excreted predominantly in the urine as phase II conjugates of the parent compound.

Safety assessment of allylalkoxybenzene derivatives used as flavouring substances - methyl eugenol and estragole

This publication is the seventh in a series of safety evaluations performed by the Expert Panel of the Flavor and Extract Manufacturers' Association (FEMA). In 1993, the Panel initiated a comprehensive program to re-evaluate the safety of more than 1700 GRAS flavouring substances under conditions of intended use. In this review, scientific data relevant to the safety evaluation of the allylalkoxybenzene derivatives methyl eugenol and estragole is critically evaluated by the FEMA Expert Panel. The hazard determination uses a mechanism-based approach in which production of the hepatotoxic sulfate conjugate of the 1'-hydroxy metabolite is used to interpret the pathological changes observed in different species of laboratory rodents in chronic and subchronic studies. In the risk evaluation, the effect of dose and metabolic activation on the production of the 1'-hydroxy metabolite in humans and laboratory animals is compared to assess the risk to humans from use of methyl eugenol and estragole as naturally occurring components of a traditional diet and as added flavouring substances. Both the qualitative and quantitative aspects of the molecular disposition of methyl eugenol and estragole and their associated toxicological sequelae have been relatively well defined from mammalian studies. Several studies have clearly established that the profiles of metabolism, metabolic activation, and covalent binding are dose dependent and that the relative importance diminishes markedly at low levels of exposure (i.e. these events are not linear with respect to dose). In particular, rodent studies show that these events are minimal probably in the dose range of 1-10 mg/kg body weight, which is approximately 100-1000 times the anticipated human exposure to these substances. For these reasons it is concluded that present exposure to methyl eugenol and estragole resulting from consumption of food, mainly spices and added as such, does not pose a significant cancer risk. Nevertheless, further studies are needed to define both the nature and implications of the dose-response curve in rats at low levels of exposure to methyl eugenol and estragole.

The subchronic oral toxicity of ethane, 1,2-bis(pentabromophenyl) (Saytex 8010) in rats

Ethane, 1,2-bis(pentabromophenyl) (EBP; CAS no. 8452-53-9) dose levels of 0, 100, 320 and 1000 mg/kg/day administered to rats by gavage in corn oil for 90 consecutive days produced no compound-related clinical signs of systemic toxicity, ocular lesions, or alterations in urinalysis, clinical chemistry, and hematology values in the treated or recovery groups. No biologically or toxicologically significant differences were observed in body weights, body weight gains, and food consumption. Statistically significant differences were found between control and high-dose animals in mean absolute or relative liver weights. Histomorphological evaluation showed in male rats low-grade liver changes consisting of minimal to slight hepatocellular vacuolation (high-dose males) and minimal to slight centrilobular hepatocytomegaly (high- and possibly mid-dose males). These changes had resolved by the end of the 28-day recovery period. No treatment-related changes were found in the livers of female rats. No treatment-related histomorphologic changes were present in any of the other tissues examined in either sex, except for evidence of aspirated test article in individual rats. The 90-day EBP no-adverse-effect level in the rat was > or = 1000 mg/kg/day, and was consistent with that of the preceding 28-day study (no-effect level > or = 1250 mg/kg/day). EBP's lack of toxicity is likely related to poor bioavailability due to its high molecular weight and low solubility.

Migratory pulmonary infiltrates in a patient with rheumatoid arthritis

The case history is described of an elderly man with rheumatoid arthritis receiving treatment with sulfasalazine and the cyclooxygenase-2 inhibitor celecoxib who presented with severe shortness of breath, cough, and decreased exercise tolerance. The chest radiograph showed unilateral alveolo-interstitial infiltrates and a biopsy specimen of the lung parenchyma showed changes consistent with acute eosinophilic pneumonia. Antibiotic treatment was unsuccessful, but treatment with steroids and discontinuation of sulfasalazine and celecoxib resulted in a marked clinical improvement confirmed by arterial blood gas analysis. The condition may have developed as an adverse reaction either to sulfasalazine or to celecoxib, although hypersensitivity to the latter has not previously been reported.

The FEMA GRAS assessment of pyrazine derivatives used as flavor ingredients. Flavor and Extract Manufacturers Association

This is the fifth in a series of safety evaluations performed by the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA). In 1993, the Panel initiated a comprehensive program to re-evaluate the safety of more than 1700 GRAS flavoring substances under conditions of intended use. Elements that are fundamental to the safety evaluation of flavor ingredients include exposure, structural analogy, metabolism, pharmacokinetics and toxicology. Flavor ingredients are evaluated individually taking into account the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of pyrazine derivatives as flavoring ingredients is evaluated.

Promoter strength in adenovirus transducing vectors: down-regulation of the adenovirus E1A promoter in 293 cells facilitates vector construction

Most adenovirus transducing vectors have the cytomegalovirus major immediate-early (CMV) or the Rous sarcoma virus long terminal repeat (RSV) promoter driving expression of the transgene. Both of these promoters are highly active in transfection and transduction assays in 293 cells, in which transducing vectors are constructed and grown, and in HeLa cells. The CMV promoter exhibits rapid activation while the RSV promoter exhibits a lag prior to the onset of viral DNA replication in transduction assays. While the use of very strong promoters facilitates expression of the transgene, high-level expression of certain gene products hinders virus construction and growth. For such genes, the use of the adenovirus type 5 E1A promoter offers advantages. The E1A promoter exhibits modest activity in HeLa cells after transfection or transduction, but very little activity in 293 cells, suggesting that the E1A promoter would permit construction and growth of vectors encoding deleterious gene products that could not be constructed with the CMV and RSV promoters. This idea was tested through attempts to construct viruses encoding the immunoglobulin loop 6 and transmembrane regions of the prostaglandin F2alpha receptor regulatory protein (FPRP), a product that inhibits adenovirus vector construction for reasons that are not clear. Only the E1A promoter permitted construction and growth of the transducing vector encoding the fragment of FPRP.

Control of methanol oxidation by ionic behavior in supercritical water

In supercritical water the rate of methanol oxidation was controlled by ionic behavior as follows: the oxidation rate of methanol decreased with increasing proton and hydroxide ion concentration, possibly due to stabilization of the reactant, while that of CO was suppressed by added protons and enhanced by added hydroxide ions.

Pharmacokinetics and absolute bioavailability of sitafloxacin, a new fluoroquinolone antibiotic, in healthy male and female Caucasian subjects

1. The aim was to compare the pharmacokinetics of sitafloxacin from a capsule formulation (dose of 500 mg sitafloxacin) and an intravenous (i.v.) formulation infused over 1 h (dose of 400 mg sitafloxacin) in healthy male and female subjects and to estimate the absolute bioavailability of sitafloxacin from the capsule formulation. 2. Following oral administration, sitafloxacin was rapidly absorbed, with a mean maximum concentration in plasma of 4.65 microgml(-1) occuring at median tmax = 1.25 h giving a mean AUC(0-infinity) = 28.1 microg h ml(-1). For the i.v. administration, a mean Cmax = 5.53 microm(-1) occurred at the end of the 1-h infusion with a mean AUC(0-infinity) = 25.4 microg h ml(-1). The mean terminal elimination half-life was 7.0 h (oral) and 6.6 h (i.v.). For the oral and i.v. formulations, the mean total plasma clearance was 296 and 263 mlmin(-1), respectively and the mean volume of distribution was 180 and 150 litres, respectively. 3. Within 48 h post-dose, approximately 61% (range 22-86%) of the administered dose was excreted unchanged in urine following capsule administration, compared with approximately 75% (range 42-101%) following the i.v. formulation. For both formulations, the renal clearance of sitafloxacin (means of 181 and 198 ml min(-1) for the capsule and i.v. doses, respectively) implies active tubular secretion of the drug. 4. The absolute bioavailability of sitafloxacin from the capsule formulation was high at 89%, with a 95% CI of 84-94%. The intersubject variability (CV%) in the sitafloxacin AUC(0-infinity) for the capsule was low at 18.6%. 5. Gender differences in the pharmacokinetics of sitafloxacin were small and would not warrant dose adjustment. 6. The findings show that the capsule formulation offers good oral bioavailability and merits further clinical evaluation of sitafloxacin as an orally effective fluoroquinolone antibacterial.

The effect of the choline head group on phospholipid hydration

The hydration behavior of three naturally occurring sphingomyelins (SM) has been studied. Adsorption isotherms for these SM, singly and in combination with other lipids, were obtained and the isotherms analyzed by the application of BET theory. The results are compared with those found previously by us for the phosphatidylcholines (PC). We find that, depending on the SM studied, both "weak" and "strong" water adsorption can be observed and thus, the presence of choline in the phospholipid head group, does not guarantee "strong" water adsorption. When the head group is removed from SM, the resulting ceramides are found to be very weak, water adsorbers. Cholesterol, when present in a mixture with SM, has a rather dramatic effect on the hydration of the SM. A mixed system of PC and SM exhibits water adsorption characteristics very similar to those exhibited by PC itself. We speculate that these hydration results may well play a role in the cell signaling action of SM and, moreover, may be closely associated with the hypothesized formation of lipid "rafts."

Lack of effect of treatment with penciclovir or acyclovir on the establishment of latent HSV-1 in primary sensory neurons in culture

Recent studies suggest reductions in establishment of herpes simplex virus, type 1 (HSV-1) latency using the nucleoside analog penciclovir compared with acyclovir in the murine model. These observations raise the possibility that the new analogs may have novel activities that directly interfere with the establishment of the latent infection, suggesting a mechanism other than simply blocking the productive infection. To determine if penciclovir has a direct action on the establishment of latency, we compared the effects of penciclovir versus acyclovir in an in vitro model of HSV-1 latency in rat dorsal root ganglia neurons in culture. In neurons in culture, both penciclovir and acyclovir were highly effective in blocking the productive infection. However, neither penciclovir nor acyclovir blocked establishment of latency as demonstrated by similar percentages of neurons expressing the latency-associated transcript (LAT). Following removal of the respective nucleoside analog, latency was maintained until reactivation was induced by nerve growth factor deprivation. Similar virus titers were recovered after induction of reactivation of latent infections, which were established in the presence of either penciclovir or acyclovir. These results indicate that neither penciclovir nor acyclovir treatment directly prevents the establishment of latent HSV-1 infections in primary sensory neurons in culture.

An evaluation of the clinical performance of newly qualified nurses: a competency based assessment

The clinical performance of newly qualified staff nurses, or their 'fitness for purpose' has become a central professional and corporate issue and highlighted as a central causes for the reforms recommended by the Peach report (Peach 1999). However the ability to gauge the performance of newly qualified nurses remains a largely subjective exercise relying upon anecdotal evidence or general statements of newly qualified nurses' feelings of inadequacy on qualification. This article seeks to address this issue by reporting the findings of project that sought to compare the expectations of senior nurses regarding the level of competence of newly qualified nurses with that of the actual level of competency as assessed by the preceptors after 8 weeks in post. Using a specifically designed instrument to assess clinical competency a comparison has been made between 139 senior nurses' expectations of the competency of newly qualified nurses and the actual competence as assessed by preceptors of 36 newly qualified nurses after 8 weeks in post. The findings indicate that the senior nurses have clear subjective expectations of the competence level of newly qualified nurses. However these expectations are consistently lower than the actual level of competency demonstrated by the newly qualified nurses as assessed by their preceptors. This research demonstrates that through the use of a validated tool newly qualified nurses consistently perform at a higher level of competency than that expected by senior nurses. The ability to estimate competency levels by objective means should be developed. Further research is needed involving a larger sample of Trusts and Schools of Nursing to replicate the results of this study and to compare methods of the assessment of performance in terms of competency in practice on qualification. It is through developments based upon research such as this that a systematic evaluation of the contribution of Schools of Nursing to the competence of newly qualified nurses can be addressed.

Long-lasting rebound cue effects following single doses of nicotine and amphetamine: implications for understanding tolerance

RATIONALE

Previous drug-discrimination studies have, with the exception of nicotine (NIC), demonstrated tolerance to the cue effects of a broad range of drugs of abuse. Barrett et al. have shown that tolerance to a drug's cue properties reflects drug-induced rebound shifts in the discrimination baseline and not a weakened or less salient cue.

OBJECTIVES

The objective of the present study was to use a discrimination task sensitive to bidirectional cue changes to characterize the interoceptive cues associated with both the primary and rebound cues produced by nicotine in an attempt to understand why a recent study by Shoaib et al. failed to observe tolerance to the nicotine cue.

METHODS

Since dopamine (DA) has been implicated in mediating the NIC cue, rats were trained to discriminate between 0.25 mg/kg amphetamine (AMPH), an indirect DA agonist, and 0.033 mg/kg haloperidol (HAL), a DA antagonist at the D2 receptor site. Training doses were chosen so that rats responded about equally on both levers when tested on saline (SAL) following acquisition. This procedure provided a behavioral baseline to assess NIC-related changes along a presumed continuum of DA-mediated cues. Following acquisition of the discrimination: (i) NIC substitution tests were conducted, (ii) rats were tested for lever choice at intervals from 2 h to 48 h following treatment with single doses of 0.25 mg/kg and 0.50 mg/kg NIC, and (iii) rats were challenged with test doses of NIC during a period of NIC rebound.

RESULTS

(i) NIC substituted for AMPH in a dose- dependent manner. (ii) At short intervals after treatment with 0.25 mg/kg and 0.50 mg/kg NIC, rats responded primarily on the AMPH lever followed by a shift to predominant responding on the HAL lever 16-24 h post-treatment, before returning to predrug levels. (iii) No evidence was observed for acute tolerance to NIC.

CONCLUSIONS

The robust and long-lasting rebound cues associated with training level doses of NIC suggest that maximal tolerance would likely develop to the NIC cue during the acquisition phase of the conventional NIC-saline discrimination study.

Carbon dioxide transport by proteic and facilitated transport membranes

Membrane separation of gases is governed by the permeability of each species across the membrane. The ratio of permeabilities yields the selectivity. Use of certain organic carriers in facilitated transport membranes and the CO2 converting enzyme carbonic anhydrase (CA) in proteic and facilitated transport membranes allows a dramatic increase in CO2 selectivity over other gases. CA has a low Km (9 mM), which we predicted would allow it to scavenge CO2 to very low partial pressures. Our goal was to determine if CA could remove CO2 from an environment at levels of 0.1% or less. Prior measurements of CO2 transport across thin supported liquid membranes showed that addition of CA enhanced CO2 flux by 3- to 100-fold. Proteic films use bifunctional reagents (e.g., glutaraldehyde) to cross-link the enzyme forming a gel. Bovine serum albumin (BSA) is often added for structural stability. Using such a preparation we examined the ability of proteic films to improve CO2 selectivity and to scavenge CO2 from a mixed gas stream. Proof-of-concept results, measured by mass spectrometry, showed a fivefold improvement in CO2 capture rate with maximal improvement at CO2 values of 1% partial pressure difference in the presence of 0 atm absolute difference. At 0.1% CO2 the membrane exhibited a 76% improvement over controls. At 0.3% CO2 the improvement is about threefold. CA proteic membranes exhibit selectivity for CO2 over oxygen and nitrogen in excess of three orders of magnitude. A CA-based proteic or facilitated transport membrane should readily achieve CO2 partial pressures of 0.05% under CELSS conditions. In addition to proteic membranes we are exploring direct immobilization of engineered CA to ultra-high-permeability teflon membranes. Site-directed mutagenesis was used to add functional groups while retaining full enzymatic activity. These results provide a basis for development of far more efficient CO2 capture proteic and facilitated transport membranes with increased selectivity to values closer to 100-fold at 1% CO2. The result will be CO2 selectivity at 0.1% on the order of 400-fold. These results exceed those obtained with other technologies.

Fibroblast expression of C-C chemokines in response to orthopaedic biomaterial particle challenge in vitro

C-C chemokines are soluble mediators that occur in a periprosthetic granuloma and influence recruitment, localization and activation of inflammatory cells. This study tested effects of titanium and polymethylmethacrylate (PMMA) particles on expression of selected C-C chemokines in cultured human fibroblasts. The C-C chemokines analyzed included monocyte chemoattractant protein-1. 2 (MCP-1. 2), monocyte inflammatory protein-1 alpha (MIP-1 alpha), and regulated on activation, normal T-cell expressed and secreted protein (RANTES). Interleukin-1 beta (IL-1 beta) served as a known stimulator of chemokine release while interleukin-6 (IL-6) expression served as a marker for fibroblast activation. Protein and mRNA signal levels were determined by ELISA and RT-PCR, respectively. The results demonstrated that exposure of fibroblasts to titanium and PMMA particles resulted in increased release of MCP-1 in a dose- and time-dependent manner. After 24 h, titanium particles maximally upregulated MCP-1 release 7-fold while PMMA particles increased MCP-1 levels 2-fold, when compared to unchallenged fibroblasts. MCP-2, MIP-1 alpha and RANTES levels remained unchanged following exposure of fibroblasts to titanium or PMMA particles at any concentration or time point tested. However, IL-1 beta stimulated release of MCP-1, MCP-2, and RANTES, but not MIP-1 alpha from the fibroblasts. IL-1 beta, not particles, exhibited the most prominent effect on MCP-1 mRNA levels. Increased release of MCP-1 from fibroblasts exposed to titanium and PMMA particles coincided with increased release of IL-6. This study suggests that release of chemoattractant factors from fibroblasts localized in periprosthetic membranes enhances the chronic inflammatory process leading to bone resorption and implant loosening.

Predicting evaporation rates and times for spills of chemical mixtures

Spreadsheet and short-cut methods have been developed for predicting evaporation rates and evaporation times for spills and constrained baths of chemical mixtures. Steady-state and time-varying predictions of evaporation rates can be made for six-component mixtures, including liquid-phase non-idealities as expressed through the UNIFAC method for activity coefficients. A group-contribution method is also used to estimate vapor-phase diffusion coefficients, which makes the method completely predictive. The predictions are estimates that require professional judgement in their application. One application that the evaporation time calculations suggest is a method for labeling chemical containers that allows one to quickly assess the time for complete evaporation of spills of both pure components and mixtures. The labeling would take the form of an evaporation time that depends on the local environment. For instance, evaporation time depends on indoor or outdoor conditions and the amount of each chemical among other parameters. This labeling would provide rapid information and an opportunity to premeditate a response before a spill occurs.

Interleukin-10 inhibits polymethylmethacrylate particle induced interleukin-6 and tumor necrosis factor-alpha release by human monocyte/macrophages in vitro

Periprosthetic membranes commonly observed at sites of total joint implant loosening exhibit abundant macrophages and particulate debris. Macrophages phagocytose orthopedic debris and release the pro-inflammatory mediators interleukin-1, interleukin-6, tumor necrosis factor-alpha, and prostaglandin E2. Populations of activated lymphocytes are often seen in periprosthetic membranes. These lymphocytes may modulate the monocyte/macrophage response to particulate debris and influence aseptic loosening. In addition, other immunologic agents, such as interleukin-10, are present in tissues harvested from the bone-implant interface of failed total joint arthroplasties. The present study examined the effects of interleukin-10 on polymethylmethacrylate (PMMA) particle challenged human monocyte/macrophages in vitro. Human monocyte/macrophages isolated from buffy coats of five healthy individuals were exposed to 1-10 microm PMMA particles. Interleukin-10 was added to the monocyte/macrophages with and without the addition of PMMA particles. Interleukin-10-induced alterations in monocyte/macrophage metabolism were determined measuring interleukin-6 and tumor necrosis factor-alpha release by the cells following exposure to PMMA particles. Exposure of the monocyte/macrophages to PMMA particles resulted in a dose-dependent release of interleukin-6 and tumor necrosis factor-alpha at 48 h. Interleukin-10 reduced the levels of interleukin-6 and tumor necrosis factor-alpha release by macrophages in response to PMMA particles in a dose-dependent manner. At 48 h, particle-induced interleukin-6 release was inhibited by 60 and 90% with 1.0 and 10.0 ng/ml treatments of interleukin-10, respectively. At 48 h, particle-induced tumor necrosis factor-alpha release was inhibited by 58 and 88% with 1.0 and 10.0 ng/ml treatments of interleukin-10, respectively. Interleukin-10 challenge alone did not significantly alter basal interleukin-6 or tumor necrosis factor-alpha release relative to control cultures. The data presented in this study demonstrate that the anti-inflammatory cytokine, interleukin-10, inhibits monocyte/macrophage release of the pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha in response to PMMA particle challenge in vitro.

Ceruminolytic efficacy in adults versus children

OBJECTIVES

An inexpensive, nontoxic ceruminolytic with reasonable efficacy that can be used by the patient or their caregivers at home could represent significant financial saving for patients and health care systems. The purpose of this study was to compare two simple ceruminolytics for in vitro efficacy.

STUDY DESIGN

Randomized controlled trial.

METHODS

Thirty-six children and 33 adults presenting to a community family practice clinic who had cerumen occluding at least one external auditory canal were randomly assigned to compare use of 10% aqueous sodium bicarbonate and 2.5% aqueous acetic acid as ceruminolytics in occlusive cerumen.

RESULTS

We were unable to demonstrate a difference between in vivo efficacy of these two ceruminolytic solutions, but both solutions were significantly more efficacious in children than adults.

CONCLUSIONS

There is a role for these ceruminolytics in children with occlusive cerumen, but adults would be better treated in another way.

Central nervous control of gill filament muscles in channel catfish

The gills of fish are innervated by cranial nerves IX and X. There have been a number of studies on the characteristics of sensory activity carried by these nerves but remarkably little is known about motor control of the gills. Efferent, motor activity to the first gill arch was recorded from the glossopharyngeal nerve in spontaneously breathing channel catfish, Ictalurus punctatus. This study addressed two objectives. The first objective was to characterize efferent branchial nerve activity in spontaneously breathing fish. Nerve recordings show bursts of activity firing in synchrony with ventilation. These bursts occurred once during either abduction or adduction of the operculum with each breath. The observed patterns of neural activity indicate that it represents motor control of gill filament abductor and adductor muscles. The data show that rhythmic output from a central pattern generator controls filament musculature during the ventilatory cycle. The second objective was to use this efferent branchial nerve activity as an index of ventilation (fictive ventilation) in fish before and after paralysis to determine if feedback from phasic mechanoreceptors affects ventilatory timing. Breath-to-breath intervals measured before and after paralysis with gallamine were not significantly different, demonstrating that rhythmic feedback from phasic mechanoreceptors in the gills and/or ventilatory musculature is not involved in the breath-to-breath timing of the normal ventilatory cycle. During the course of these experiments many fish exhibited coughing. Coughs were characterized by a distinctive pattern of nerve activity that was not altered by paralysis. Overall, the data indicate that phasic mechanoreceptor feedback during normal breathing has no effect on the pattern of central motor control of gill filament muscles.

Trimethylaminuria: the fish malodor syndrome

The fish malodor syndrome (also known as the fish odor syndrome and trimethylaminuria) is a metabolic disorder characterized by the presence of abnormal amounts of the dietary-derived tertiary amine, trimethylamine, in the urine, sweat, expired air, and other bodily secretions. Trimethylamine itself has the powerful aroma of rotting fish, and this confers upon the sufferer a highly objectionable body odor, which can be destructive to the personal, social, and work life of the affected individual. In recent years, much progress has been made at all levels-clinical, epidemiological, biochemical, and genetic-in our understanding of this unfortunate condition. The present article summarizes this progress, draws attention to the different types of fish malodor syndrome, and highlights the current needs in the treatment of such patients.

Ontogeny of CLCN3 chloride channel gene expression in human pulmonary epithelium

Human fetal bronchopulmonary epithelia secrete liquid, and this chloride (Cl)-dependent process is important for normal lung growth. At the time of birth there is a maturational transition from a secretory to an absorptive phenotype. The pathways for Cl exit from the apical membrane which are required for fetal lung liquid secretion are unknown but are thought to be independent of the cystic fibrosis transmembrane conductance regulator. We determined the ontogeny of expression of the CLCN family of voltage-dependent Cl channel genes (CLCN2 through 6, K(a) and K(b)) in the human lung to identify potential pathways for pulmonary liquid secretion. Only CLCN3 and CLCN6 messenger RNA were detected by Northern analysis of fetal whole lung tissue. Ribonuclease protection assays confirmed the expression of CLCN3 and also revealed expression of CLCN2. The ontogeny of expression of these two channels was similar, peaking in midgestation and declining postnatally. In situ hybridization localized the CLCN2 and CLCN3 messages to airway and distal pulmonary epithelia and to pulmonary blood vessels. We conclude that CLCN3 is expressed in human airway epithelia and expression is developmentally regulated. The contribution of these channels to pulmonary epithelial liquid transport and lung development remains to be determined.

Distribution of chloride channel-2-immunoreactive neuronal and astrocytic processes in the hippocampus

The chloride homeostasis of neurons and non-neuronal cells is maintained in part by a voltage-sensitive inwardly rectifying chloride conductance through the chloride channel-2. This channel is activated by hyperpolarization and extracellular hypotonicity. In the present study, hippocampal sections were immunostained for chloride channel-2, and somata and dendrites of both pyramidal and non-pyramidal cells were found to be immunoreactive. In addition, glial processes in the vicinity of small blood vessels were also immunostained, whereas the neuropil of strata pyramidale and lacunosum-moleculare contained chloride channel-2-positive punctate structures. Electron microscopy and double immunostaining using antibodies against chloride channel-2 and glial fibrillary acidic protein confirmed that the dense network of chloride channel-2-positive processes corresponds to the end feet of astrocytes. The distribution of chloride channel-2-immunoreactive astrocytes was inhomogeneous throughout the hippocampus: strata oriens, pyramidale and lacunosum-moleculare of CA1-CA3 and the outer molecular layer of the dentate gyrus contained the majority of immunoreactive end feet, whereas the other layers showed sparse labeling. Subcellular studies demonstrated that, in addition to astrocytes, chloride channel-2 was localized in the membrane of dendrites, dendritic spines, cell bodies and axon initial segments of neurons, frequently close to, or within active zones of, symmetrical synapses.Thus, chloride channel-2 appears to be involved in transmembrane chloride movements associated with GABAergic synaptic transmission. The specific laminar distribution of chloride channel-2-positive astroglial processes coinciding with that of GABAergic axon terminals suggests that the network of astrocytes may be able to siphon and deliver Cl(-) ions to layers with intense GABAergic transmission, thereby increasing the efficacy of GABA(A) receptor-mediated inhibition.

Inducible cyclic AMP early repressor produces reactivation of latent herpes simplex virus type 1 in neurons in vitro

Herpes simplex virus type 1 (HSV-1) establishes a latent infection in neurons of the peripheral nervous system. During latent HSV-1 infection, viral gene expression is limited to latency-associated transcripts (LAT). HSV-1 remains latent until an unknown mechanism induces reactivation. The ability of the latent virus to periodically reactivate and be shed is essential to the transmission of disease. In vivo, the stimuli that induce reactivation of latent HSV-1 include stress, fever, and UV damage to the skin at the site of initial infection. In vitro, in primary neurons harboring latent HSV-1, nerve growth factor (NGF) deprivation or forskolin treatment induces reactivation. However, the mechanism involved in the induction of reactivation remains poorly understood. An in vitro neuronal model of HSV-1 latency was used to investigate potential mechanisms involved in the induction of reactivation of latent HSV-1. In situ hybridization analysis of neuronal cultures harboring latent HSV-1 showed a marked, rapid decrease in the percentage of LAT-positive neurons following induction of reactivation by NGF deprivation or forskolin treatment. Western blot analysis showed a corresponding increase in expression of the cellular transcription factor inducible cyclic AMP early repressor (ICER) during reactivation. In transient-transfection assays, ICER downregulated LAT promoter activity. Expression of ICER from a recombinant adenoviral vector induced reactivation and decreased the percentage of LAT-positive neurons in neuronal cultures harboring latent HSV-1. These results indicate that ICER represses LAT expression and induces reactivation of latent HSV-1.

ClC-2 chloride channels contribute to HTC cell volume homeostasis

Membrane Cl(-) channels play an important role in cell volume homeostasis and regulation of volume-sensitive cell transport and metabolism. Heterologous expression of ClC-2 channel cDNA leads to the appearance of swelling-activated Cl(-) currents, consistent with a role in cell volume regulation. Since channel properties in heterologous models are potentially modified by cellular background, we evaluated whether endogenous ClC-2 proteins are functionally important in cell volume regulation. As shown by whole cell patch clamp techniques in rat HTC hepatoma cells, cell volume increases stimulated inwardly rectifying Cl(-) currents when non-ClC-2 currents were blocked by DIDS (100 microM). A cDNA closely homologous with rat brain ClC-2 was isolated from HTC cells; identical sequence was demonstrated for ClC-2 cDNAs in primary rat hepatocytes and cholangiocytes. ClC-2 mRNA and membrane protein expression was demonstrated by in situ hybridization, immunocytochemistry, and Western blot. Intracellular delivery of antibodies to an essential regulatory domain of ClC-2 decreased ClC-2-dependent currents expressed in HEK-293 cells. In HTC cells, the same antibodies prevented activation of endogenous Cl(-) currents by cell volume increases or exposure to the purinergic receptor agonist ATP and delayed HTC cell volume recovery from swelling. These studies provide further evidence that mammalian ClC-2 channel proteins are functional and suggest that in HTC cells they contribute to physiological changes in membrane Cl(-) permeability and cell volume homeostasis.

In vitro reaction to orthopaedic biomaterials by macrophages and lymphocytes isolated from patients undergoing revision surgery

Periprosthetic tissues observed at sites of loose total joint implants exhibit abundant macrophages, lymphocytes, fibroblasts and particulate debris. Macrophages phagocytose orthopaedic debris and release proinflammatory cytokines, chemokines, matrix metalloproteinases and other substances. In addition, other cell types present in tissues harvested from the bone-implant interface are thought to influence periprosthetic bone resorption. The present study examined the effects of polymethylmethacrylate (PMMA), cobalt chrome molybdenum alloy (CoCr), and titanium-alloy particle challenge on macrophages co-cultured with lymphocytes in vitro. Potential synergistic effects of lymphocytes on macrophage activation were determined by measuring interleukin-6 and tumor necrosis factor-alpha release following exposure to orthopaedic biomaterial particles. Exposure of macrophages or macrophages co-cultured with lymphocytes to all three types of particles resulted in increased release of interleukin-6 and tumor necrosis factor-alpha at 48 h, when compared to macrophages or macrophages co-cultured with lymphocytes, respectively, cultured in the absence of particles. Lymphocytes isolated from periprosthetic tissues secreted increased basal levels of cytokines relative to peripheral blood lymphocytes. Higher doses of PMMA and titanium-alloy particles stimulated increased levels of cytokine release in the macrophage and macrophage/lymphocyte groups. In contrast, a higher dose of CoCr particles (0.075% v/v) was not as effective as the 0.015% v/v dose, indicating probable CoCr toxicity. The macrophage/lymphocyte co-culture did not show synergism between the two types of cells with respect to cytokine release. T-cells at the bone-implant interface may alter the biological response to particulate debris.

Urinary thiocyanate levels as a biomarker for the generation of inorganic cyanide from benzyl cyanide in the rat

A colorimetric procedure was developed and validated for the determination of thiocyanate in rat urine over the concentration range of 7-7000 microg/ml. It was applied to the determination of thiocyanate following its oral administration to male and female rats. The mean percentage urinary recoveries of sodium thiocyanate given by oral gavage at 10 and 100 mg/kg were 60 and 39%, respectively, for male rats and 89 and 73% for females over a period of 3 days. Most of the elimination occurred in the 0-48-h period post-dosing but significant amounts were still being excreted in the 48-72-h period. It was concluded from these results that the recoveries of urinary thiocyanate were such that this anion was suitable for use as a biomarker for the release of cyanide from organonitriles such as benzyl cyanide. Benzyl cyanide (150 mg/kg) administered orally to rats led to markedly increased urinary thiocyanate levels; for male rats this was equivalent to 54% of the dose and for females this was 65% over a period of 3 days. When adjusted for incomplete recoveries of the marker, thiocyanate, these values equated to 61 and 89%, respectively. It was concluded that this validated assay could be used to assess cyanide release from topically applied fragrance organonitriles (Potter, J., Smith, R.L., Api, A.M., 2000. An assessment of the release of inorganic cyanide from the fragrance materials, benzyl cyanide, geranyl nitrile and citronellyl nitrile applied dermally to the rat. Food and Chemical Toxicology 39, 147-151).

An assessment of the release of inorganic cyanide from the fragrance materials benzyl cyanide, geranyl nitrile and citronellyl nitrile applied dermally to the rat

Organonitriles are widely used as components of fragrances that are incorporated into consumer products, many of which are for human topical use. Some organontriles are readily broken down metabolically to potentially toxic inorganic cyanide. Studies were therefore undertaken to assess whether this occurs with three representative fragrance nitriles, namely, benzyl cyanide, geranyl nitrile and citronellyl nitrile when applied dermally to the rat. The nitriles (benzyl cyanide, 150 mg/kg; geranyl and citronellyl nitriles, 400 mg/kg) were applied to the shaved backs of rats and maintained under occlusion for 24 h. Urine samples were collected for 0-24 h, 24-48 h and 48-72 h from the time of first application. These samples were analysed for thiocyanate, a biomarker for cyanide formation in vivo, as described previously (Potter, J., Smith, R.L., Api, A.M., 2000. Urinary thiocyanate levels as a biomarker for the generation of inorganic cyanide from benzyl cyanide in the rat. Food and Chemical Toxicology 39, 141-146). In the case of benzyl cyanide, there was a marked increase in urinary thiocyanate levels attributable to the release of cyanide in vivo. The amount of thiocyanate recovered was equivalent to 37% of the dose for males and 32% for females. For geranyl nitrile there was no significant increase in urinary thiocyanate excretion and there was only a marginal increase in the case of citronellyl nitrile that was equivalent to 0.40% of the applied dose for males and 0.29% for females.

In situ stimulation of groundwater denitrification with formate to remediate nitrate contamination

In situ stimulation of denitrification has been proposed as a mechanism to remediate groundwater nitrate contamination. In this study, sodium formate was added to a sand and gravel aquifer on Cape Cod, MA, to test whether formate could serve as a potential electron donor for subsurface denitrification. During 16- and 10-day trials, groundwater from an anoxic nitrate-containing zone (0.5-1.5 mM) was continuously withdrawn, amended with formate and bromide, and pumped back into the aquifer. Concentrations of groundwater constituents were monitored in multilevel samplers after up to 15 m of transport by natural gradient flow. Nitrate and formate concentrations were decreased 80-100% and 60-70%, respectively, with time and subsequent travel distance, while nitrite concentrations inversely increased. The field experiment breakthrough curves were simulated with a two-dimensional site-specific model that included transport, denitrification, and microbial growth. Initial values for model parameters were obtained from laboratory incubations with aquifer core material and then refined to fit field breakthrough curves. The model and the lab results indicated that formate-enhanced nitrite reduction was nearly 4-fold slower than nitrate reduction, but in the lab, nitrite was completely consumed with sufficient exposure time. Results of this study suggest that a long-term injection of formate is necessary to test the remediation potential of this approach for nitrate contamination and that adaptation to nitrite accumulation will be a key determinative factor.

Ethylamine in human urine

The urinary excretion of ethylamine has been measured in 200 unrelated healthy volunteers (100 male, 100 female) who maintained their normal diet. The average daily output was 7.82+/-7.03 mg (mean+/-S.D.) (8.01+/-7.40 male; 7.64+/-6.67 female) with a range of values spreading from 0.22 to 35.27 mg. Dietary studies investigating 41 food substances did not highlight any major sources of this amine, except that drinking tea increased subsequent urinary ethylamine levels.

Compound heterozygosity for missense mutations in the flavin-containing monooxygenase 3 (FM03) gene in patients with fish-odour syndrome

Fish-odour syndrome is a highly unpleasant disorder of hepatic trimethylamine (TMA) metabolism characterized by a body odour reminiscent of rotting fish, due to excessive excretion of the malodorous free amine. Although fish-odour syndrome may exhibit as sequelae with other conditions (e.g. liver dysfunction), many patients exhibit an inherited, more persistent form of the disease. Ordinarily, dietary-derived TMA is oxidized to the nonodorous N-oxide by hepatic flavin-containing monooxygenase 3 (FMO3). Our previous demonstration that a mutation, P153L (C to T), in the FMO3 gene segregated with the disorder and inactivated the enzyme confirmed that defects in FMO3 underlie the inherited form of fish-odour syndrome. We have investigated the genetic basis of the disorder in two further affected pedigrees and report that the three propositi are all compound heterozygotes for causative mutations of FMO3. Two of these individuals possess the P153L (C to T) mutation and a novel mutation, N61S (A to G). The third is heterozygous for novel, M4341 (G to A), and previously reported, R492W (C to T), mutations. Functional characterization of the S61, 1434 and W492 variants, via baculovirus-mediated expression in insect cells, confirmed that all three mutations either abolished, or severely attenuated, the capacity of the enzyme to catalyse TMA N-oxidation. Although 1434 and W492 were also incapable of catalysing the S-oxidation of methimazole, S61 was fully active with this sulphur-containing substrate. Since an asparagine is conserved at the equivalent position to N61 of FMO3 in mammalian, yeast and Caenorhabditis elegans FMOs, the characterization of the naturally occurring N61S (A to G) mutation may have identified this asparagine as playing a critical role specifically in FMO-catalysed N-oxidation.

Characterization of promoter function and cell-type-specific expression from viral vectors in the nervous system

Viral vectors have become important tools to effectively transfer genes into terminally differentiated cells, including neurons. However, the rational for selection of the promoter for use in viral vectors remains poorly understood. Comparison of promoters has been complicated by the use of different viral backgrounds, transgenes, and target tissues. Adenoviral vectors were constructed in the same vector background to directly compare three viral promoters, the human cytomegalovirus (CMV) immediate-early promoter, the Rous sarcoma virus (RSV) long terminal repeat, and the adenoviral E1A promoter, driving expression of the Escherichia coli lacZ gene or the gene for the enhanced green fluorescent protein. The temporal patterns, levels of expression, and cytotoxicity from the vectors were analyzed. In sensory neuronal cultures, the CMV promoter produced the highest levels of expression, the RSV promoter produced lower levels, and the E1A promoter produced limited expression. There was no evidence of cytotoxicity produced by the viral vectors. In vivo analyses following stereotaxic injection of the vector into the rat hippocampus demonstrated differences in the cell-type-specific expression from the CMV promoter versus the RSV promoter. In acutely prepared hippocampal brain slices, marked differences in the cell type specificity of expression from the promoters were confirmed. The CMV promoter produced expression in hilar regions and pyramidal neurons, with minimal expression in the dentate gyrus. The RSV promoter produced expression in dentate gyrus neurons. These results demonstrate that the selection of the promoter is critical for the success of the viral vector to express a transgene in specific cell types.