Comparison of VEGF-producing cells in periprosthetic osteolysis

The pro-angiogenic cytokine vascular endothelial growth factor (VEGF) has been implicated in periprosthetic osteolysis and subsequent aseptic loosening of implants following total hip arthroplasty (THA). The goal of this study was to investigate whether increased VEGF at the bone-implant interface is secondary to a greater number of VEGF-producing cells or to increased VEGF production by individual cells. Real time polymerase chain reaction (RT-PCR) techniques were used to assess the expression of VEGF mRNA (isoforms 121, 165, 189) in periprosthetic tissues from revision THAs. Immunofluorescence was used to determine both differences in overall cellularity and in VEGF-producing cell type (macrophages, fibroblasts, endothelial cells) between patients with periprosthetic osteolysis (OL) and a control group undergoing primary THA for osteoarthritis (OA). Quantitative analysis of VEGF release in periprosthetic membranes via RT-PCR demonstrated no significant difference in the per-cell mRNA production of VEGF isoforms 121 165, or 189 between OL and OA patient groups. Immunofluorescence showed both higher cellularity and higher overall VEGF expression in the OL group. Immunofluorescence also showed a significant increase in macrophages in the OL group, but no significant difference in the proportion of fibroblasts or endothelial cells between the OL and OA groups. Co-localization of CD68+ and CD11b+ macrophage fluorescent signals with VEGF signal was greater in the OL group than in the OA group. Our results demonstrate that increased VEGF in OL periprosthetic tissue compared to OA synovium is correlated to increased numbers of VEGF-producing CD68+ and CD11b+ macrophages. Impact statement: Aseptic loosening, caused in large part by OL, remains the major cause of failed THAs leading to revision surgery. At the bone-implant interface, we found increased numbers of macrophages-cellular mediators of OL-and increased VEGF expression. VEGF may be a possible target for therapeutic intervention in mitigating OL.

Denitrification potential in stream sediments impacted by acid mine drainage: effects of pH, various electron donors, and iron

Acid mine drainage (AMD) contaminates thousands of kilometers of stream in the western United States. At the same time, nitrogen loading to many mountain watersheds is increasing because of atmospheric deposition of nitrate and increased human use. Relatively little is known about nitrogen cycling in acidic, heavy-metal-laden streams; however, it has been reported that one key process, denitrification, is inhibited under low pH conditions. The objective of this research was to investigate the capacity for denitrification in acidified streams. Denitrification potential was assessed in sediments from several Colorado AMD-impacted streams, ranging from pH 2.60 to 4.54, using microcosm incubations with fresh sediment. Added nitrate was immediately reduced to nitrogen gas without a lag period, indicating that denitrification enzymes were expressed and functional in these systems. First-order denitrification potential rate constants varied from 0.046 to 2.964 day(-1). The pH of the microcosm water increased between 0.23 and 1.49 pH units during denitrification. Additional microcosm studies were conducted to examine the effects of initial pH, various electron donors, and iron (added as ferrous and ferric iron). Decreasing initial pH decreased denitrification; however, increasing pH had little effect on denitrification rates. The addition of ferric and ferrous iron decreased observed denitrification potential rate constants. The addition of glucose and natural organic matter stimulated denitrification potential. The addition of hydrogen had little effect, however, and denitrification activity in the microcosms decreased after acetate addition. These results suggest that denitrification can occur in AMD streams, and if stimulated within the environment, denitrification might reduce acidity.

Growth-Biosynthesis Relationships in Erythromycin Fermentation

The relationship of erythromycin biosynthesis to growth appears to vary with the fermentation medium in which the microorganism is grown. In a medium containing a complex nitrogen source, antibiotic production occurred only when growth was halted, whereas in a glycine-containing synthetic medium the two parameters increased at nearly the same time. An autostimulation of antibiotic production through addition of erythromycin is reported. Also described is the use of a labeled precursor as an index of biosynthesis rates during short periods of time.

The effects of titanium and polymethylmethacrylate particles on osteoblast phenotypic stability

Wear particles generated following total joint arthroplasty interact with cells at the periprosthetic margin and induce an inflammatory response that contributes to osteolysis, aseptic loosening, and implant failure. This study examined the long-term effects of particles from two commonly implanted materials, titanium (Ti) and polymethylmethacrylate (PMMA), on cell viability and metabolism over a 21-day time course, using the human osteoblast-like cell line MG-63. Addition of particles was not associated with increased cell death or nitric oxide production at the particle concentration chosen. Collagen production was increased with exposure to titanium particles, whereas alkaline phosphatase and osteocalcin expression remained unchanged following exposure to both types of particles. The data show that titanium but not PMMA particles shifts bone cell metabolism to preferentially produce fibrous tissue rather than bone.

Assessment of nitrification potential in ground water using short term, single-well injection experiments

Nitrification was measured within a sand and gravel aquifer on Cape Cod, MA, using a series of single-well injection tests. The aquifer contained a wastewater-derived contaminant plume, the core of which was anoxic and contained ammonium. The study was conducted near the downgradient end of the ammonium zone, which was characterized by inversely trending vertical gradients of oxygen (270 to 0 microM) and ammonium (19 to 625 microM) and appeared to be a potentially active zone for nitrification. The tests were conducted by injecting a tracer solution (ambient ground water + added constituents) into selected locations within the gradients using multilevel samplers. After injection, the tracers moved by natural ground water flow and were sampled with time from the injection port. Rates of nitrification were determined from changes in nitrate and nitrite concentration relative to bromide. Initial tests were conducted with (15)N-enriched ammonium; subsequent tests examined the effect of adding ammonium, nitrite, or oxygen above background concentrations and of adding difluoromethane, a nitrification inhibitor. In situ net nitrate production exceeded net nitrite production by 3- to 6- fold and production rates of both decreased in the presence of difluoromethane. Nitrification rates were 0.02-0.28 mumol (L aquifer)(-1) h(-1) with in situ oxygen concentrations and up to 0.81 mumol (L aquifer)(-1) h(-1) with non-limiting substrate concentrations. Geochemical considerations indicate that the rates derived from single-well injection tests yielded overestimates of in situ rates, possibly because the injections promoted small-scale mixing within a transport-limited reaction zone. Nonetheless, these tests were useful for characterizing ground water nitrification in situ and for comparing potential rates of activity when the tracer cloud included non-limiting ammonium and oxygen concentrations.

The FEMA GRAS assessment of benzyl derivatives used as flavor ingredients

This publication is the eighth 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 and in the context of the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of benzyl derivatives as flavoring ingredients is evaluated. The group of benzyl derivatives was reaffirmed as GRAS (GRASr) based, in part, on their self-limiting properties as flavoring substances in food; their rapid absorption, metabolic detoxication, and excretion in humans and other animals, their low level of flavor use, the wide margins of safety between the conservative estimates of intake and the no-observed-adverse effect levels determined from subchronic and chronic studies and the lack of significant genotoxic and mutagenic potential. This evidence of safety is supported by the fact that the intake of benzyl derivatives as natural components of traditional foods is greater than their intake as intentionally added flavoring substances.

The FEMA GRAS assessment of phenethyl alcohol, aldehyde, acid, and related acetals and esters used as flavor ingredients

This publication is the ninth 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 and in the context of the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of phenethyl alcohol, aldehyde, acid, and related acetals and esters as flavoring ingredients is evaluated. The group of phenethylalcohol, aldehyde, acid, and related acetals and esters was reaffirmed as GRAS (GRASr) based, in part, on their self-limiting properties as flavoring substances in food, their rapid absorption, metabolic detoxication, and excretion in humans and other animals, their low level of flavor use, the wide margins of safety between the conservative estimates of intake and the no-observed-adverse effect levels determined from subchronic and chronic studies and the lack of significant genotoxic and mutagenic potential. This evidence of safety is supported by the fact that the intake of phenethyl alcohol, aldehyde, acid, and related acetals and esters as natural components of traditional foods is greater than their intake as intentionally added flavoring substances.

Ocular toxoplasmosis in mice: comparison of two routes of infection

This paper aims to test the influence of route of infection (intravitreal and instillation) on the course of ocular toxoplasmosis in mice, using the Toxoplasma gondii Me-49 strain. All mice inoculated intravitreally or by instillation presented the same pattern of infection. Using either route, parasites were observed in the retinal vessel with the formation of a glial reaction in the inner plexiforme layer and discontinuity of the pigmented epithelium of the retina 7 days after infection. However, when the intravitreal route was used a more intense inflammatory infiltrate was observed in the retina. The results suggest that inoculation route remarkably influences the inflammatory pattern in ocular toxoplasmosis and that the instillation route should be preferentially used in experimental infections in the murine ocular model of infection by T. gondii, specially with small animals where there is extensive needle damage, which is not observed in the instillation route.

Evidence for PTZ-like cues as a function of time following treatment with chlordiazepoxide: implications for understanding tolerance and withdrawal

The present study used a two-lever, drug-discrimination procedure to train rats to discriminate between the cues associated with 5 mg/kg of the anxiolytic, chlordiazepoxide (CDP) and 15 mg/kg of the anxiogenic, pentylenetetrazol (PTZ), to investigate the relationship between withdrawal and acute tolerance. Training doses of the two drugs were chosen so that rats responded about equally on both levers when tested on saline (SAL). Following acquisition of the discrimination, rats were injected with 10 mg/kg CDP and tested for lever choice at various intervals from 6 h to 192 h. These tests revealed that cues associated with CDP withdrawal lasted approximately three times longer than the cues associated with the drug's primary effects. At the shortest retest interval (6 h) after treatment with 10 mg/kg CDP, rats responded primarily on the CDP lever, followed by a shift to predominant responding on the PTZ lever at the 16 h and 24 h intervals before returning to predrug, baseline levels at the longer intervals (48-192 h). In order to investigate the relationship between tolerance and withdrawal to the cue properties of CDP, CDP dose-response curves were determined 24 h following treatment with SAL or 10 mg/kg CDP. Acute tolerance, as defined by a rightward, parallel shift in the dose-response function, was observed in the rats pretreated with CDP. Furthermore, it was evident that the baseline shift associated with CDP withdrawal, rather than a weaker drug cue, accounted for acute tolerance. The results from this study are relevant to evaluating the role positive and negative reinforcement play in motivating compulsive drug use.

The FEMA GRAS assessment of hydroxy- and alkoxy-substituted benzyl derivatives used as flavor ingredients

This publication is the ninth 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 and in the context of the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of hydroxy- and alkoxy-substituted benzyl derivatives as flavoring ingredients is evaluated. The group of hydroxy- and alkoxy-benzyl derivatives was reaffirmed as GRAS (GRASr) based, in part, on their self-limiting properties as flavoring substances in food; their rapid absorption, metabolic detoxication, and excretion in humans and other animals; their low level of flavor use; the wide margins of safety between the conservative estimates of intake and the no-observed-adverse effect levels determined from subchronic and chronic studies and the lack of significant genotoxic and mutagenic potential. This evidence of safety is supported by the fact that the intake of hydroxy- and alkoxy-substituted benzyl derivatives as natural components of traditional foods is greater than their intake as intentionally added flavoring substances.

A procedure for the safety evaluation of natural flavor complexes used as ingredients in food: essential oils

A scientifically based guide has been developed to evaluate the safety of naturally occurring mixtures, particularly essential oils, for their intended use as flavor ingredients. The approach relies on the complete chemical characterization of the essential oil and the variability of the composition of the oil in the product intended for commerce. Being products of common plant biochemical pathways, the chemically identified constituents are organized according to a limited number of well-established chemical groups called congeneric groups. The safety of the intake of the each congeneric group from consumption of the essential oil is evaluated in the context of data on absorption, metabolism, and toxicology of members of the congeneric group. The intake of the group of unidentified constituents is evaluated in the context of the consumption of the essential oil as a food, a highly conservative toxicologic threshold, and toxicity data on the essential oil or an essential oil of similar chemotaxonomy. The flexibility of the guide is reflected in the fact that high intake of major congeneric groups of low toxicologic concern will be evaluated along with low intake of minor congeneric groups of significant toxicological concern (i.e., higher structural class). The guide also provides a comprehensive evaluation of all congeneric groups and constituents that account for the majority of the composition of the essential oil. The overall objective of the guide is to organize and prioritize the chemical constituents of an essential oil in order that no reasonably possible significant risk associated with the intake of essential oil goes unevaluated. The guide is, however, not intended to be a rigid checklist. The Flavor and Extract Manufacturers Association (FEMA) Expert Panel will continue to evaluate each essential oil on a case by case basis applying their scientific judgment to insure that each natural flavor complex is exhaustively evaluated.

A nutrition support team led by general surgeons decreases inappropriate use of total parenteral nutrition on a surgical service

The purpose of this study was to decrease the number of inappropriate orders for total parenteral nutrition (TPN) in surgical patients. From February 1999 through November 2000 and between July 2001 and June 2002, the surgeon-guided adult nutrition support team (NST) at a university hospital monitored new TPN orders for appropriateness and specific indication. In April 1999, the NST was given authority to discontinue inappropriate TPN orders. Indications, based on the American Society for Parenteral and Enteral Nutrition (ASPEN) standards, included short gut, severe pancreatitis, severe malnutrition/catabolism with inability to enterally feed > or =5 days, inability to enterally feed >50 per cent of nutritional needs > or =9 days, enterocutaneous fistula, intra-abdominal leak, bowel obstruction, chylothorax, ischemic bowel, hemodynamic instability, massive gastrointestinal bleed, and lack of abdominal wall integrity. The number of inappropriate TPN orders declined from 62/194 (32.0%) in the first 11 months of the study to 22/168 (13.1%) in the second 11 months (P < 0.0001). This number further declined to 17/215 (7.9%) in the final 12 months of data collection, but compared to the second 11 months, this decrease was not statistically significant (P = 0.1347). The involvement of a surgical NST was associated with a reduction in inappropriate TPN orders without a change in overall use.

The passage of trimethylamine across rat and human skin

Trimethylamine is a volatile low molecular weight tertiary aliphatic amine that has known toxicity and the potential for human exposure from industrial and environmental sources is considerable. It is generally believed that absorption across the skin is an unimportant route of entry but there is little, if any, supporting evidence for this assumption. Passage across rat and human skin has been investigated employing excised skin circles in an in vitro diffusion cell apparatus. Trimethylamine was found to penetrate readily when applied to the epidermal surface of skin at three different dose levels (0.1, 1.0 and 10 mg per skin membrane 0.32 cm2). The apparent dermal flux was calculated as 3.40 +/- 1.60, 58.3 +/- 30.6 and 265.0 +/- 155.0 microg/cm2/h for rat and 0.98 +/- 0.75, 9.21 +/- 3.06 and 92.7 +/- 31.9 microg/cm2/h for human at the three dose levels, respectively. Both rat and human skin was able to act as a reservoir, with the trimethylamine not remaining in the stratum corneum but passing through. When presented to the underneath of rat and human skin circles, both [U-14C]-trimethylamine and [U-14C]-trimethylamine N-oxide were able to pass from the dermis to the epidermis. Small but detectable amounts of trimethylamine were oxidised to its N-oxide during passage through the skin.

How representative is the population covered by the RCGP spotter practice scheme? Using Geographical Information Systems to assess

BACKGROUND

The Royal College of General Practitioners Weekly Returns Service (WRS) is a network of sentinel general practices providing weekly data on illnesses diagnosed in general practice across England and Wales. The WRS contributes to the surveillance of infectious disease, most notably influenza. We use Geographical Information Systems (GIS) techniques to establish whether the practice populations of the current WRS are representative of the general population.

METHODS

This study compares the practice population with the general population using the Department of the Environment, Transport and Regions (DETR) Indices of Deprivation 2000 scores for English wards.

RESULTS

Comparisons at the national level reveal that the WRS population is less deprived than the general population. At a supra-regional level the WRS practice population shows the same North-South differences as the national population, but the proportions of patients in the more deprived and least deprived wards are more exaggerated in the WRS population. A supplementary analysis reveals that the WRS has no patients in the most deprived wards of London.

CONCLUSION

The differences have implications for the future recruitment of practices to the WRS. Previous studies have demonstrated the effect of socio-economic deprivation on GP consultation rates. To ensure that the consultation rates reported by the WRS will better reflect consulting patterns in the general population the WRS will need to recruit practices with patients in the most deprived areas of the South and less deprived areas in the North of England. This study demonstrates the value of GIS in the establishment of surveillance systems.

Ocular toxoplasmosis: the role of retinal pigment epithelium migration in infection

Our aim was to study the migration of retinal pigmented epithelium (RPE) into the retinal layer during infection of C57BL/6 mice with Toxoplasma gondii. Eyes from infected and non-infected animals were analyzed on the 60th day of infection by light and transmission electron microscopy. Non-infected eyes showed a normal morphology. In contrast, we observed free parasites in the retinal vasculature, the presence of mononuclear inflammatory infiltrate (MNII) and parasites in the vasculature of choroids in infected eyes. No inflammatory infiltrate was observed; RPE cells were identified near the MNII in nuclear and plexiforme layers. RPE cells were also found on the ganglion cell layer and in the outer segments of the photoreceptor. The morphology showed that RPE cells caused a discontinuity in the nuclear and plexiforme layers. Clusters of parasites were found surrounded by RPE cells and MNII in the inner plexiforme layers. Ultrastructural analysis showed that RPE cells migrated through the epithelium into the inner retinal layers. We did not observe Toxoplasma cysts in many eyes in which pathological changes were detected. Only 8.3% of the animals had Toxoplasma cysts in the inner nuclear layer in the absence of inflammatory cells. The migration of RPE cells can be triggered by a disruption of the RPE monolayer or injury to the neural retina, as in the case of toxoplasmosis.

Safety evaluation of natural flavour complexes

Natural flavour complexes (NFCs) are chemical mixtures obtained by applying physical separation methods to botanical sources. Many NFCs are derived from foods. In the present paper, a 12-step procedure for the safety evaluation of NFCs, 'the naturals paradigm', is discussed. This procedure, which is not intended to be viewed as a rigid check list, begins with a description of the chemical composition of the commercial product, followed by a review of the data on the history of dietary use. Next, each constituent of an NFC is assigned to one of 33 congeneric groups of structurally related substances and to one of three classes of toxic potential, each with its own exposure threshold of toxicological concern. The group of substances of unknown structure is placed in the class of greatest toxic potential. In subsequent steps, for each congeneric group the procedure determines the per capita intake, considers metabolic pathways and explores the need and availability of toxicological data. Additional toxicological and analytical data may be required for a comprehensive safety evaluation. The procedure concludes with an evaluation of the NFC in its entirety, also considering combined exposure to congeneric groups. The first experiences with the use of this procedure are very promising. Future safety evaluations of larger numbers of NFCs will indicate the usefulness of the system, either in its present form or in a form modified on the basis of experience.

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.

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.