Highly-automated, high-throughput replication of yeast-based logic circuit design assessments

We describe an experimental campaign that replicated the performance assessment of logic gates engineered into cells of Saccharomyces cerevisiae by Gander et al. Our experimental campaign used a novel high-throughput experimentation framework developed under Defense Advanced Research Projects Agency's Synergistic Discovery and Design program: a remote robotic lab at Strateos executed a parameterized experimental protocol. Using this protocol and robotic execution, we generated two orders of magnitude more flow cytometry data than the original experiments. We discuss our results, which largely, but not completely, agree with the original report and make some remarks about lessons learned. Graphical Abstract.

Low-frequency rTMS to the parietal lobe increases eye-movement carryover and decreases hazard rating

The persistence of attentional set from one task to a secondary unrelated task, revealed through carryover of eye movements, has been attributed to increased activation in the parietal lobe and decreased activation to the frontal lobe. To directly test this, we adopted a modified version of the Thompson and Crundall (2011) paradigm using low-frequency repetitive TMS to P3 and F3. In each trial, participants viewed letter-strings that were arranged horizontally, vertically, or randomly across the screen before viewing a road image and providing a hazardousness rating for it. The orientation of the letter search influenced eye movements to the road images and this carryover was greater following stimulation to F3 than to P3 (or sham). Furthermore, hazardous ratings were lower following P3 stimulation. These results confirm the involvement of attentional orienting and switching mechanisms in the carryover of eye movements. It is suggested that this "attentional inertia" effect will increase with greater orienting of attentional resources in an initial task and poor inhibition of previously-relevant settings between tasks.

Sudden early-morning awakening impairs immediate tactical planning in a changing 'emergency' scenario

This was a realistic military-type exercise assessing unexpected, abrupt early-morning awakening effects on immediate 'executive function' and the ability to comprehend and deal with a sudden emergency under a changing situation. Twenty (average age 21years) healthy, highly motivated junior officer reservists were assigned randomly to two equal, independent groups, unforewarned as to what would happen. The experimental group was woken abruptly at 03:00h (<3h sleep) and confronted immediately with a 'paper exercise' of an enemy attack, requiring a feasible plan of engagement with minimal loss of resources, to be completed within 15min. A control group slept until 07:30h; they were then presented with the identical emergency 1h later. Participants worked individually, under time pressure, receiving written information, map and other details, all containing relevant, irrelevant and misleading information. Halfway through, they were given (unexpectedly) a critical update necessitating a change of tactics. Performance was scored blind by instructors, under five categories. Eight of the experimental group versus three controls failed overall, with significant group differences on three specific categories relying on flexible decision-making: 'identification of available cover', 'use of available assets' and 'extraction of relevant from irrelevant information'. Other, logical and highly trained skills were unimpaired. Ours was a 'worst case scenario', combining short sleep, circadian 'trough' and sleep inertia, all of which differentiated the two groups, unlike typical laboratory studies. Nevertheless, it was relevant to real-life situations involving highly motivated, trained individuals making critical innovative decisions in the early morning versus the normal waking day.

‘Young’ Oral Fibroblasts Are Geno/Phenotypically Distinct

Wound healing within the oral mucosa results in minimal scar formation compared with wounds within the skin. We have recently demonstrated distinct differences in the aging profiles of cells (oral mucosal and patient-matched skin fibroblasts) isolated from these tissues. We hypothesized that the increased replicative potential of oral mucosal fibroblasts may confer upon them preferential wound-healing capacities. Passage-matched early cultures of oral mucosal fibroblasts and skin fibroblasts demonstrated distinct gene expression profiles, with several genes linked to wound healing/tissue repair. This was related to an increased ability of the ‘replicatively younger’ oral mucosal fibroblasts to repopulate a wound space and reorganize their surrounding extracellular matrix environment, key activities during the wound-healing process. We conclude that oral mucosal fibroblasts exhibit a preferential healing response in vivo, due to their ‘replicatively younger’ phenotype when compared with that of patient-matched skin fibroblasts.

Increased Oral Fibroblast Lifespan Is Telomerase-independent

Oral mucosal wound-healing is characterized by rapid re-epithelialization and remodeling, with minimal scar formation. This may be attributed to the distinct phenotypic characteristics of the resident fibroblasts. To test this hypothesis, we investigated patient-matched oral mucosal and skin fibroblasts. Compared with skin fibroblasts, oral mucosal fibroblasts had longer proliferative lifespans, underwent more population doublings, and experienced senescence later, which was directly related to longer telomere lengths within oral mucosal fibroblasts. The presence of these longer telomeres was independent of telomerase expression, since both oral oral mucosal fibroblasts and skin fibroblasts were negative for active telomerase, as assessed according to the Telomeric Repeat Amplification Protocol. This study has demonstrated that, compared with skin fibroblasts, oral mucosal fibroblasts are ‘younger’, with a more embryonic/fetal-like phenotype that may provide a notable advantage for their ability to repair wounds in a scarless fashion.

Optimisation of the hydrogen peroxide pre-treatment of titanium: surface characterisation and protein adsorption

BACKGROUND

Researchers have attempted to enhance titanium osseointegration by modifying its surface properties, including via H(2)O(2) pre-treatment, with reported treatment regimes varying from minutes/hours, to weeks.

OBJECTIVE

This study examined the effects of various H(2)O(2) treatments on titanium surface topography/roughness, chemical composition/oxide thickness, hydrophilicity and plasma protein adsorption.

MATERIALS AND METHODS

Titanium discs were treated with 30% H(2)O(2) for 0-24 h or 1-4 weeks and subjected to atomic force microscopy (AFM), scanning electron microscopy (SEM), profilometry, X-ray photon spectroscopy and contact angle analysis. For protein adsorption, whole plasma and FITC-conjugated serum albumin were added to 0-24 h and 1-4 week H(2)O(2)-treated discs and examined by SEM and fluorescence microscopy, respectively.

RESULTS

AFM, SEM and profilometry demonstrated that 1-6 h H(2)O(2)-treated discs exhibited subtle alterations in surface topography/roughness at the nanometre scale, although 24 h and 1-4 week H(2)O(2)-treated discs exhibited much greater increases in surface roughness, in the micrometre range. Maximal increases in surface oxide thickness and chemical modification were identified between 1 h-4 weeks and 3 h-4 weeks, respectively, although no increases in oxygen/titanium (O1s : Ti2p) molar ratio or in hydrophilicity were evident. Plasma and serum albumin adsorption increased on 1-24 h H(2)O(2)-treated discs, with further increases on 1-4 week H(2)O(2)-treated discs.

CONCLUSIONS

Based upon the present data and previous findings, this study supports the concept that surface topography/roughness and oxide composition/thickness, are more significantly modified by H(2)O(2) treatment and more influential to protein adsorption than hydrophilicity. Additionally, it can be hypothesized that the 24 h H(2)O(2) treatment of titanium surfaces, which induced micrometre scale changes in roughness and protein adsorption, to those associated with enhanced osteoblast attachment/behaviour, mineralisation and subsequent implant osseointegration, would be most beneficial.

A UK-based investigation of inter- and intra-observer reproducibility of Gleason grading of prostatic biopsies

AIMS

The frequency of prostatic core biopsies to detect cancer has been increasing with more widespread prostate specific antigen (PSA) testing. Gleason score has important implications for patient management but morphological reproducibility data for British practice are limited. Using literature-based criteria nine uropathologists took part in a reproducibility study.

METHODS

Each of the nine participants submitted slides from consecutive cases of biopsy-diagnosed cancer assigned to the Gleason score groups 2-4, 5-6, 7 and 8-10 in the original report. A random selection of slides was taken within each group and examined by all pathologists, who were blind to the original score. Over six circulations, new slides were mixed with previously read slides, resulting in a total of 47 of 81 slides being read more than once.

RESULTS

For the first readings of the 81 slides, the agreement with the consensus score was 78% and overall interobserver agreement was kappa 0.54 for Gleason score groups 2-4, 5-6, 7, 8-10. Kappa values for each category were 0.33, 0.56, 0.44 and 0.68, respectively. For the 47 slides read more than once, intra-observer agreement was 77%, kappa 0.66. The study identified problems in core biopsy interpretation of Gleason score at levels 2-4 and 7. Patterns illustrated by Gleason as 2 tended to be categorized as 3 because of the variable acinar size and unassessable lesional margin. In slides with consensus Gleason score 7, 13% of readings were scored 6 and in slides with consensus 6, 18% of readings were scored 7.

CONCLUSIONS

Recommendations include the need to increase objectivity of the Gleason criteria but limits of descriptive morphology may have to be accepted.

A study of Gleason score interpretation in different groups of UK pathologists; techniques for improving reproducibility

AIMS

To test the effectiveness of a teaching resource (a decision tree with diagnostic criteria based on published literature) in improving the proficiency of Gleason grading of prostatic cancer by general pathologists.

METHODS

A decision tree with diagnostic criteria was developed by a panel of urological pathologists during a reproducibility study. Twenty-four general histopathologists tested this teaching resource. Twenty slides were selected to include a range of Gleason score groups 2-4, 5-6, 7 and 8-10. Interobserver agreement was studied before and after a presentation of the decision tree and criteria. The results were compared with those of the panel of urological pathologists.

RESULTS

Before the teaching session, 83% of readings agreed within +/- 1 of the panel's consensus scores. Interobserver agreement was low (kappa = 0.33) compared with that for the panel (kappa = 0.62). After the presentation, 90% of readings agreed within +/- 1 of the panel's consensus scores and interobserver agreement amongst the pathologists increased to kappa = 0.41. Most improvement in agreement was seen for the Gleason score group 5-6.

CONCLUSIONS

The lower level of agreement among general pathologists highlights the need to improve observer reproducibility. Improvement associated with a single training session is likely to be limited. Additional strategies include external quality assurance and second opinion within cancer networks.

Genomic imbalances in 70 snap-frozen cervical squamous intraepithelial lesions: associations with lesion grade, state of the HPV16 E2 gene and clinical outcome

Host genomic abnormalities may determine the natural history of cervical squamous intraepithelial lesions (SILs). We undertook comparative genomic hybridisation analysis of epithelium carefully microdissected from 70 cervical SILs, the largest series to date. In contrast to previous studies, we used frozen sections for optimal DNA quality and examined whether patterns of DNA copy number imbalance (CNI) are characteristic of SIL grade, human papillomavirus (HPV) status and postoperative recurrence. We identified more CNIs in cervical SIL than previously described, with more CNIs per case in high-grade squamous intraepithelial lesion (HG-SIL) than in low-grade squamous intraepithelial lesion (LG-SIL) (P=0.04). While some CNIs were seen at similar frequencies in HG-SIL and LG-SIL, others, including gain on 1q, 3q and 16q, were found frequently in HG-SIL but not in LG-SIL. There were significantly more CNIs per case in HG-SILs showing loss of the HPV16 E2 gene (a repressor of viral oncogene transcription) (P=0.026) and in HG-SILs that subsequently recurred (P=0.04). Our data are consistent with sequential acquisition of CNIs in cervical SIL progression. Higher frequency of CNI in association with E2 gene loss supports in vitro evidence that high-risk HPV integration is associated with genomic instability. Further investigation of the clinical value of specific host genomic abnormalities in cervical SIL is warranted.

Fluoride-induced changes to proteoglycan structure synthesised within the dentine–pulp complex in vitro

Fluoride is known to influence mineralisation patterns within dentine, where alterations in the post-translational modification of proteoglycans (PG) have been proposed as an implicating factor. In light of recent studies elucidating changing PG profiles in the transition of predentine to mineralised dentine, this study investigates the influence of fluoride on the major PG populations (decorin, biglycan and versican) within the pulp, predentine and dentine. Tooth sections from rat incisors were cultured for 14 days in the presence 0, 1 and 6 mM sodium fluoride and the PG extracted from the pulp, predentine and dentine matrices. PG species and corresponding metabolites were identified by their immuno-reactivity to antibodies against decorin, biglycan and versican. Component glycosaminoglycan chains were characterised with respect to their nature, chain length and disaccharide composition. Levels of PG extracted from pulp and predentine were reduced, particularly for biglycan. Fluoride did not influence levels of decorin or versican within predentine or dentine, although the processing of these macromolecules within pulp and predentine was affected, particularly at higher fluoride concentrations. Levels of dermatan sulfate were reduced within pulp and predentine, although the effect was less pronounced for predentine. Fluoride reduced sulfation of glycosaminoglycan chains within pulp and predentine tissues, with a notable reduction in Deltadi6S evident. In all three tissues, glycosaminoglycan chain length was reduced. Considering the various roles for PG in the dentine-pulp complex, either directly or indirectly in the mineralisation process, changes in the synthesis, structure and processing of the different PG species within the pulp, predentine and dentine matrices provides a further molecular explanation for the altered mineralisation patterns witnessed during fluorosis.

Extracellular matrix metabolites as potential biomarkers of disease activity in wound fluid: lessons learned from other inflammatory diseases?

The new era of pharmacogenetics has identified a potential for individuals to receive customized treatments for a variety of disease states. For such individualized treatments to fulfil their potential, it will be essential for clinicians to be able to monitor disease activity, ideally in a rapid, noninvasive fashion. The accessibility of the skin offers much potential to develop noninvasive tests of metabolic and disease activity for clinical use. Impaired human wound healing in the skin is a chronic inflammatory disorder in which the development of such tests has considerable potential, aiding clinical decision making and monitoring responses to treatment. This review article discusses how studies in other human diseases have highlighted potential biochemical markers (biomarkers) of disease activity in secreted biofluids, as aids to determining disease and metabolic activity within tissues. Using, as examples, lessons learned in the study of disease activity and prognosis of other chronic inflammatory conditions, such as osteoarthritis and periodontal disease, this review highlights the potential of dermal extracellular matrix (ECM) components (collagens, proteoglycans, hyaluronan and glycoproteins) for such uses. The limitations of currently utilized techniques and the concept that analysis of ECM components in wound fluid may represent useful biomarkers of disease activity are also discussed.

The influence of fluoride exposure on dentin mineralization using an in vitro organ culture model

This study aimed to characterize fluoride-induced alterations in dentin mineralization within a dentin-pulp organ culture system. Tooth sections derived from male Wistar rat incisors were cultured in Trowel-type culture for 14 days, in the presence of 0 mM, 1 mM, 3 mM and 6 mM sodium fluoride. Tooth sections were processed and analyzed for uptake of fluoride, its subsequent effect on dentin mineralization by tetracycline hydrochloride incorporation and mineral composition, expressed as calcium/phosphorous (Ca/P) ratios. Tetracycline hydrochloride incorporation was demonstrated to decrease with increased fluoride exposure, accompanied by significant increases in both Ca/P ratios and fluoride incorporation. These findings provide further evidence that the established alterations in dentin formation during fluorosis are a consequence of disruption to the mineralization process, and provide a model system with which to investigate further the potential role the extracellular matrix plays in inducing the apparent changes in mineral composition.

TGF-beta latency-associated peptides (LAPs) in human dentin matrix and pulp

Transforming growth factor (TGF)-beta s in dentin matrix provide a pool of bioactive molecules, but association with latency-associated peptides (LAPs) may influence their activity. We investigated TGF-beta 1, -beta 2, and -beta 3 LAP expression in sound and carious human teeth. Teeth were fixed and processed immediately following extraction prior to staining with rabbit polyclonal antibodies to the TGF-beta LAPs. A soluble dentin matrix fraction was prepared from dissected human dentin and sequential extraction of pulpal ECM was performed prior to purification. Fractions were Western blotted and probed with the LAP antibodies. All three LAPs were present in odontoblasts, cells of the pulp, and predentin; however, no staining of mineralized dentin matrix was seen. Similar patterns of expression were seen in carious tissue. Expression of TGF-beta LAPs in cells and pulpal matrix of healthy and carious teeth will be important in regulation of TGF-beta activity and may modulate the tissue response to injury.

Comparison of the antioxidant properties of wound dressing materials--carboxymethylcellulose, hyaluronan benzyl ester and hyaluronan, towards polymorphonuclear leukocyte-derived reactive oxygen species

In chronic wounds, factors are released which perpetuate inflammatory processes, including polymorphonuclear leukocyte (PMN)-derived reactive oxygen species (ROS), such as superoxide radical (O(2)*-) and hydroxyl radical (*OH) species. The glycosaminoglycan, hyaluronan, has established antioxidant properties towards ROS, although the antioxidant potential of wound dressing biomaterials, such as 75% benzyl esterified hyaluronan (BEHA) and carboxymethylcellulose (CMCH), are less characterised. This study compared the antioxidant properties of high and low molecular weight hyaluronan (HMWT HA and LMWT HA), BEHA and CMCH towards ROS, generated by stimulated PMN in vitro. The antioxidant capacities of each biomaterial were assessed by their inhibition of O(2)*- -induced cytochrome C reduction, generated via PMN stimulation by phorbol myristyl acetate (PMA); and their inhibition of *OH-induced 2-deoxy-D-ribose degradation, generated by PMA stimulated PMN in the presence of a ferric chloride-EDTA chelate. All biomaterials, except LMWT HA, possessed dose-dependent antioxidant properties against O(2)*-, BEHA having greatest antioxidant potential, followed by HMWT HA and CMCH. HMWT HA exhibited the highest dose-dependent antioxidant properties towards *OH, followed by BEHA and CMCH. LMWT HA demonstrated no antioxidant properties towards *OH. These antioxidant activities, particularly towards O(2)*-, may be beneficial in removing the initial source of ROS necessary for the secondary formation of *OH, implicated as a causal factor for the extensive metabolic alterations observed in chronic wounds.

The influence of fluoride on the cellular morphology and synthetic activity of the rat dentine-pulp complex in vitro

Exposure to high fluoride concentrations in the immediate environment of the tissue is recognized to result in the post-translational modification of non-collagenous dentine extracellular matrix (ECM) components, potentially altering dentine mineralization. However, less is known about the effects of fluoride exposure on the morphology or metabolism of the cells associated with the dentine-pulp complex. This study examined the effects of fluoride exposure at defined concentrations on the cellular morphology and ECM synthetic activities of odontoblasts and pulpal fibroblasts by the culture of tooth sections from male Wistar rat incisors in Trowel-type cultures for up to 14 days, in the presence and absence of 6mM sodium fluoride. Histomorphometric analysis of the dentine-pulp complex of sodium fluoride-exposed tooth sections demonstrated no obvious gross morphological differences with respect to the odontoblasts and pulpal fibroblasts throughout the 14-day culture period, in comparison with unexposed tooth sections. No significant differences in odontoblast and pulpal fibroblast cell numbers were determined in the absence and presence of fluoride. Image analysis examination of odontoblast cytoplasmic:nuclear (C/N) ratios also showed no significant differences in fluoride-exposed and unexposed tooth sections, although reductions in the C/N ratios of pulpal fibroblasts were evident in fluoride-exposed sections at days 10 and 14. No significant differences in predentine width were observed in fluoride-exposed and unexposed tooth sections over the 14-day culture period. Autoradiography following [3H]proline incorporation into the dentine-pulp complex demonstrated inhibition of collagen synthesis, particularly by the odontoblasts in tooth sections exposed to 6mM sodium fluoride. These findings, in association with those from previous studies, imply that dentine ECM alterations may contribute to the altered mineralization of dentine during fluorosis, rather than secretory-related changes in odontoblast morphology.

Comparison of the antioxidant properties of HYAFF-11p75, AQUACEL and hyaluronan towards reactive oxygen species in vitro

In chronic wounds, a number of host factors are released which perpetuate the inflammatory process, including polymorphonuclear leukocyte (PMN)-derived reactive oxygen species (ROS), such as superoxide radical (O2*-) and hydroxyl radical (*OH) species. The glycosaminoglycan. hyaluronan, has been shown to act as an antioxidant towards ROS, although the potential for biomaterials, such as HYAFF -11p75 (the 75% benzyl ester of hyaluronan) and AQUACEL (carboxymethylcellulose), to act in this manner has yet to be elucidated. This study compared the antioxidant properties of high and low molecular weight hyaluronan (HMWT HA and LMWT HA), HYAFF -11p75, AQUACEL and an AQUACEL /hyaluronan composite (AQUACEL /HA) against O2*- and *OH. The antioxidant capacities of each material were assessed by their ability to inhibit cytochrome C reduction by O2*- fluxes, generated via the oxidation of hypoxanthine by xanthine oxidase, and their inhibition of 2-deoxy-D-ribose degradation by *OH fluxes, generated by the reaction of hydrogen peroxide (H2O2) and iron (Fe2+). All materials studied possessed dose dependent antioxidant properties towards O2*-, with HYAFF 11p75 having the greatest antioxidant potential towards these species, followed by AQUACEL, HMWT HA, AQUACEL /HA and LMWT HA. Only HMWT HA exhibited dose dependent antioxidant properties towards *OH at the fluxes examined. Gas chromatography/mass spectrometry analysis implied that ester bonds between the hyaluronan backbone and benzyl groups of HYAFF -11p75 are highly susceptible to O2*- hydrolysis, with the de-esterified benzyl alcohol being rapidly degraded in the presence of *OH. This data supports the hypothesis that HYAFF -11p75 has greater antioxidant capacity towards O2*-, due to the esterified benzyl groups providing alternative sites for O2*- attack other than the hyaluronan backbone of HYAFF -11p75 itself and explains the inability of HYAFF -11p75 to scavenge *OH, due to benzyl alcohol degradation by *OH. The antioxidant activities of these biomaterials, particularly HYAFF -11p75 and AQUACEL, towards O2*- could be beneficial, as the scavenging of PMN-derived O2*- may remove initial sources of O2*- and further prevent the secondary formation of *OH. These ROS are thought to be a primary causal factor for the extensive degradation and metabolic alterations observed in chronic wounds.

A randomized, controlled trial to assess a novel colorectal cancer screening strategy: the conversion strategy--a comparison of sequential sigmoidoscopy and colonoscopy with immediate conversion from sigmoidoscopy to colonoscopy in patients with an abnormal screening sigmoidoscopy

OBJECTIVE

Our study was a randomized, controlled trial to assess a novel strategy that provides comprehensive colorectal cancer screening in a single visit versus traditional sigmoidoscopy and, where appropriate, colonoscopy on a subsequent day.

METHODS

Consecutive patients referred for screening were randomized to control or so-called "conversion" groups. Patients in the control group were prepared for sigmoidoscopy with oral phospho-soda. Those with an abnormal sigmoidoscopy were scheduled for colonoscopy on a future day after oral polyethylene glycol preparation. In the conversion group, patients were prepared with oral phosphosoda. Patients with a polyp >5 mm or multiple diminutive polyps were converted from sigmoidoscopy to colonoscopy, allowing comprehensive screening in a single visit. Clinical outcomes were assessed by postprocedure physician and patient questionnaires.

RESULTS

Two hundred thirty-five patients were randomized (control = 121, conversion = 114). In the control group, 28% had an indication for colonoscopy. Three of 33 (9%) with an abnormal sigmoidoscopy did not return for colonoscopy. At colonoscopy, 27% had a proximal adenoma. In the conversion group, 28% had an abnormal sigmoidoscopy and underwent conversion to colonoscopy. Forty-one percent undergoing colonoscopy in the conversion group had a proximal adenoma. Physicians reported no differences in preparation or procedure difficulty, whereas patients reported no differences in the level of comfort or overall satisfaction between groups. When queried regarding preferences for future screening, 96% chose the conversion strategy.

CONCLUSIONS

The conversion strategy led to similar outcomes compared to traditional screening while improving compliance with colonoscopy in patients with an abnormal sigmoidoscopy.

Reactive oxygen species: a potential role in the pathogenesis of periodontal diseases

The pathological events leading to the destruction of the periodontium during inflammatory periodontal diseases are likely to represent complex interactions involving an imbalance in enzymic and non-enzymic degradative mechanisms. This paper aims to review the increasing body of evidence implicating reactive oxygen species (ROS), derived from many metabolic sources, in the pathogenesis of periodontal tissue destruction. ROS are generated predominantly by polymorphonuclear leukocytes (PMN) during an inflammatory response and are regarded as being highly destructive in nature. The detection of ROS oxidation products, the elevation of iron and copper ions, which catalyse the production of the most reactive radical species, and the identification of an imbalance in the oxidant/antioxidant activity within periodontal pockets, suggests a significant role for ROS in periodontal tissue destruction. In vitro studies have shown that ROS are capable of degrading a number of extracellular matrix components including proteoglycans, resulting in the modification of amino acid functional groups, leading to fragmentation of the core protein, whilst the constituent glycosaminoglycan chains undergo limited depolymerisation. The identification and characterisation of connective tissue metabolites in gingival crevicular fluid (GCF) resulting from the degradation of periodontal tissues, notably alveolar bone, provides further evidence for a role for ROS in tissue destruction associated with inflammatory periodontal diseases.

Unexpected difficult intubation in the patient with Morning Glory syndrome

Morning Glory syndrome is an uncommon congenital optic disc anomaly with occasional systemic associations. A case of unsuspected difficult intubation in a three-year old patient is described in this case report.

The modification of alveolar bone proteoglycans by reactive oxygen species in vitro

Reactive oxygen species (ROS) are being increasingly implicated in the connective tissue degradation associated with chronic inflammatory conditions, such as periodontal disease. The present study investigated the effects of ROS on the proteoglycans (PG) of alveolar bone which are important structural components within the periodontium. PG were isolated from ovine alveolar bone and exposed to increasing concentrations of hydrogen peroxide (H2O2) or to a hydroxyl radical (.OH) flux for 1 h or 24 h, and the degradation products examined for depolymerisation and chemical modification of the PG structure. ROS were demonstrated to be capable of degrading alveolar bone PG in vitro, the .OH species resulting in greater modification than H2O2. The degradative effects observed included cleavage of the protein core and depolymerisation of the GAG chains. The core proteins were more susceptible to degradation than the GAG chains in the presence of H2O2 alone, although both the core proteins and the GAG chains were extensively degraded in the presence of a .OH flux for both 1 h and 24 h. Exposure of the PG to .OH for 24 h resulted in significant modification to the amino acid composition with decreases in the proportion of leucine and the complete loss of proline, tyrosine and phenylalanine evident. The results highlight the potential role of ROS as an important mechanism in considering the pathology of periodontal tissue destruction.

Degradation of glycosaminoglycans by reactive oxygen species derived from stimulated polymorphonuclear leukocytes

The effect of reactive oxygen species (ROS), generated by in vitro stimulation of isolated PMN upon the main GAG components of mineralised and non-mineralised connective tissues was investigated. PMN were isolated from whole blood and the production of the ROS superoxide (O2.-) and hydroxyl radicals (.OH) was stimulated by the addition of phorbol myristyl acetate (PMA) and PMA/FeCl3-EDTA chelate respectively and their production assessed over a 24 h period. The glycosaminoglycans (GAG), hyaluronan, chondroitin 4-sulphate and dermatan sulphate, were exposed to the ROS fluxes, incubated at 37 degrees C for 1 h and 24 h. GAG fragmentation was examined by gel exclusion chromatography and modification to hexuronic acid and hexosamine residues determined. Stimulation of PMN with PMA resulted in a burst of O2.- production for 1 h, which was sustained at a reduced level for 24 h. Fragmentation of GAG was observed for all GAG examined. Modification to the GAG was evident, with hyaluronan being more susceptible to loss of GAG residues than sulphated GAG. Modification of sugar residues increased with the incubation time and loss of the hexuronic acid residues was greater than loss of hexosamine residues. Addition of FeCl3-EDTA chelate, which led to the generation of .OH and was sustained over the 24 h period, demonstrated similar trends of GAG modification although increased degradation and loss of hexosamine and hexuronic acid were observed. GAG chains are constituents of PGs and their modification is likely to affect the function of these macromolecules and be of importance in considering the pathogenesis of inflammatory diseases, including periodontal diseases.

Influence of titanium oxide and titanium peroxy gel on the breakdown of hyaluronan by reactive oxygen species

The molecular events occurring at the interface between titanium and connective tissue were investigated in order to help explain the unique biocompatible properties of titanium implants and their successful osseointegration into bone tissue. In this study the influence of commercially pure titanium and titanium peroxy gels on the breakdown of the connective tissue component and serum derived factor, hyaluronan, by reactive oxygen species (ROS), produced during the insertion of an implant in vivo, was examined. Hyaluronan breakdown was monitored in vitro in the presence of a hydroxyl radical flux, generated in the presence and absence of titanium powder and discs. Parallel studies examined the breakdown of hyaluronan by hydroxyl radicals in the presence of a titanium peroxy gel, prepared by incubation of the titanium powder or discs in concentrated hydrogen peroxide. The hyaluronan degradation products were separated according to their hydrodynamic size by gel exclusion chromatography. Similarly, experiments were also performed examining the degradation of 2-deoxy-D-ribose by a hydroxyl radical flux in order to demonstrate the detrimental potential of the hydroxyl radicals and to provide a measure of the effectiveness of titanium and titanium peroxy gels as scavengers of ROS. Titanium reduced the harmful effects of the hydroxyl radicals on the breakdown of hyaluronan, presumably acting as a scavenger for the reactive species, possibly by absorbing them into its surface oxide layer, which spontaneously forms on the surface. In contrast, the formation of a titanium peroxy gel from the titanium powder or on the surface of titanium discs enhanced breakdown of both the hyaluronan chains and 2-deoxy-D-ribose. The implications of these findings with regards to the biocompatible nature of the titanium and the ability of these implants to successfully osseointegrate are discussed.

The chemical modification of glycosaminoglycan structure by oxygen-derived species in vitro

The effect of reactive oxygen species (ROS) on the chemical structure of glycosaminoglycans (GAG) was studied in order to consider their role in connective tissue damage during an inflammatory disease state such as periodontal disease. GAG were exposed to a radical generating system for 1 h and analysed by gel filtration for fragmentation and chemically with respect to uronic acid, hexosamine and sulfate content. Non-sulfated GAG, hyaluronan and chondroitin, were most susceptible to depolymerisation and chemical modification of uronic acid and hexosamine residues by ROS. Depolymerisation and chemical modification of sulfated GAG, chondroitin 4-sulfate, dermatan sulfate and heparan sulfate was significantly less than for non-sulfated GAG. The highly sulfated GAG heparin showed minimal depolymerisation by ROS, but uronic acid residues were readily modified. Analysis of the ROS-exposed residues suggests that uronic acid is capable of degrading to a 3-carbon aldehyde, malondialdehyde. Chondroitin sulfate exposed to ROS resulted in marginal desulfation. The results suggest that the presence of sulfate on the GAG chain may protect the molecule against ROS attack. However, chemical modification of GAG may affect proteoglycan function and be of importance in considering connective tissue destruction in a variety of pathological situations, including periodontal disease.

Ethical and practical implications of the human genome initiative for family medicine

Major advances in predictive genetic testing resulting from the Human Genome Initiative could change significantly the routine practice of family medicine. Family physicians should be aware that increased genetic information may affect patients' abilities to acquire and maintain insurance and employment and that interested parties will have incentives to seek this information. The social consequences of genetic information, as well as increased health promotion efforts, may raise problems of informed consent and confidentiality. In addition to their ethical implications, these developments will also affect the practice of family physicians in practical ways such as record keeping. We discuss cases that illustrate the potential impact of these emerging technologies on the practice of family medicine.

Commentary: maintaining the somatic/germ-line distinction: some ethical drawbacks

Determinations of the ethical acceptability of genetic therapy have relied on several distinctions in attempts to separate ethically acceptable genetic therapy from those possible therapies that could lead to genetic modifications of future human beings. One distinction that has been proposed is that genetic modifications of human somatic cells is ethically acceptable but that germ-line genetics modifications would be ethically objectionable. This paper examines several serious difficulties which call into question the ethical relevance of a somatic/germ-line distinction.

Prenatal screening for illegal drugs. Dilemma for the nurse-midwife

Prenatal screening for illegal drugs poses very complex ethical problems for the nurse-midwife who must make the decision whether to screen for illegal drugs and whether to report positive results to state child abuse investigators. We argue that the results of prenatal screening for illegal drug use should not be used for determination of child abuse and that the nurse-midwife should not be required to report the results of these screens for illegal drugs to state child protection agencies. It is far from clear that required reporting offers any benefit to the fetus or future child, and there are serious ramifications of reporting for the fetus, the pregnant woman, and the nurse-midwifery profession. However, we do argue that prenatal screening for both illegal and legal drug use should be encouraged and should be done as early as possible in the pregnancy. Prenatal screening for drugs should only be used by the nurse-midwife as a diagnostic procedure wherein standard informed consent and confidentiality restraints are maintained.

Monoclonal antibodies M340 and UJ181.4 recognize antigens associated with primitive neuroectodermal tumours/tissues

Monoclonal antibodies UJ181.4 and M340 were raised from separate fusions using either human foetal brain or medulloblastoma tissue as immunogens. The antibodies are both of IgG isotype and bind to their target antigens with affinities in excess of 10(-9) M. Both monoclonal antibodies have been shown to bind to primitive neuroectodermal tumours and human foetal brain. Expression of the two antigens is developmentally regulated as no binding is detected on adult brain as determined by a variety of indirect binding assays. The two monoclonal antibodies can be clearly distinguished by their migration in a pH gradient (isoelectric focussing gels). UJ181.4 and M340 clearly recognize two different epitopes, as it is not possible to block the binding of one antibody with an excess of the other. In addition, careful study of the binding profiles of the two reagents suggest that they recognize two distinct antigens, although these have not been biochemically characterized. The reagents have proved particularly useful in both the differential diagnosis of the small round cell tumours of childhood and anaplastic brain tumours. In addition, they have formed part of a panel of reagents used for the immunomagnetic depletion of neuroblasts from bone marrow and have been used for targeting radionuclides to tumour cells in the intrathecal compartment.