Sjögren's syndrome. Proposed criteria for classification

The term "Sjögren's syndrome" (SS) is frequently used to describe the occurrence of keratoconjunctivis sicca and xerostomia in association with an autoimmune disorder. However, well-defined criteria for the classification of SS have not been established, and this diagnosis is being applied to a wide spectrum of conditions, ranging from clear "autoimmune" disease in some patients, to sicca complaints without evidence of a systemic immune process in elderly patients. Here, we review the clinical and laboratory features of patients referred for evaluation of sicca symptoms. In particular, we emphasize the need for care in choosing the site for minor salivary gland biopsy, and we describe the histologic features that aid in the evaluation of these biopsy specimens. In an attempt to identify a population of patients whose conditions might have a common etiopathogenesis and, thus, a common treatment program, we propose the following criteria for a diagnosis of SS: 1) objective evidence of keratoconjunctivis sicca, as documented by rose bengal or fluorescein dye staining; 2) objective evidence of diminished salivary gland flow; 3) minor salivary gland biopsy, obtained through normal mucosa, with the specimen containing at least 4 evaluable salivary gland lobules, and having an average of at least 2 foci/4 mm2; 4) evidence of a systemic autoimmune process, as manifested by the presence of autoantibodies, such as rheumatoid factor and/or antinuclear antibody. The diagnosis of "definite SS" would be made when all 4 criteria are met; the diagnosis of "possible SS" would be made when 3 criteria are present. Specific exclusions for this diagnosis are preexisting lymphoma, graft-versus-host disease, sarcoidosis, and acquired immunodeficiency disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Overlapping functions of components of a bacterial Sec-independent protein export pathway

We describe the identification of two Escherichia coli genes required for the export of cofactor-containing periplasmic proteins, synthesized with signal peptides containing a twin arginine motif. Both gene products are homologous to the maize HCF106 protein required for the translocation of a subset of lumenal proteins across the thylakoid membrane. Disruption of either gene affects the export of a range of such proteins, and a complete block is observed when both genes are inactivated. The Sec protein export pathway was unaffected, indicating the involvement of the gene products in a novel export system. The accumulation of active cofactor-containing proteins in the cytoplasm of the mutant strains suggests a role for the gene products in the translocation of folded proteins. One of the two HCF106 homologues is encoded by the first gene of a four cistron operon, tatABCD, and the second by an unlinked gene, tatE. A mutation previously assigned to the hcf106 homologue encoded at the tatABCD locus, mttA, lies instead in the tatB gene.

Randomised trial of efficacy and safety of oral ganciclovir in the prevention of cytomegalovirus disease in liver-transplant recipients. The Oral Ganciclovir International Transplantation Study Group [corrected]

BACKGROUND

Cytomegalovirus (CMV) disease is a frequent cause of serious morbidity after solid-organ transplantation. The prophylactic regimens used to prevent CMV infection and disease have shown limited benefit in seronegative recipients. We studied the safety and efficacy of oral ganciclovir in the prevention of CMV disease following orthotopic liver transplantation.

METHODS

Between December, 1993, and April, 1995, 304 liver-transplant recipients were randomised to receive oral ganciclovir 1000 mg or matching placebo three times a day. Seronegative recipients of seronegative livers were excluded. Study drug was administered as soon as the patient was able to take medication by mouth (no later than day 10) until the 98th day after transplantation. Patients were assessed at specified times throughout the first 6 months after surgery for evidence of CMV infection, CMV disease, rejection, opportunistic infections, and possible drug toxicity.

FINDINGS

The Kaplan-Meier estimate of the 6-month incidence of CMV disease was 29 (18.9%) of 154 in the placebo group, compared with seven (4.8%) of 150 in the ganciclovir group (p < 0.001). In the high-risk group of seronegative recipients (R-) of seropositive livers (D+), incidence of CMV disease was 11 (44.0%) of 25 in the placebo group, three (14.8%) of 21 in the ganciclovir group (p = 0.02). Significant benefit was also observed in those receiving antibodies to lymphocytes, where the incidence of CMV disease was 12 (32.9%) of 37 in the placebo group and two (4.6%) of 44 in the ganciclovir group (p = 0.002). Oral ganciclovir reduced the incidence of CMV infection (placebo 79 [51.5%] of 154; ganciclovir 37 [24.5%] of 150; p < 0.001) and also reduced symptomatic herpes-simplex infections (Kaplan-Meier estimates: placebo 36 [23.5%] of 154; ganciclovir five [3.5%] of 150; p < 0.001).

INTERPRETATION

Oral ganciclovir is a safe and effective method for the prevention of CMV disease after orthotopic liver transplantation.

Oral ganciclovir for patients with cytomegalovirus retinitis treated with a ganciclovir implant. Roche Ganciclovir Study Group

BACKGROUND

The intraocular ganciclovir implant is effective for local treatment of cytomegalovirus retinitis in patients with the acquired immunodeficiency syndrome (AIDS), but it does not treat or prevent other systemic manifestations of cytomegalovirus infection.

METHODS

Three hundred seventy-seven patients with AIDS and unilateral cytomegalovirus retinitis were randomly assigned to one of three treatments: a ganciclovir implant plus oral ganciclovir (4.5 g daily), a ganciclovir implant plus oral placebo, or intravenous ganciclovir alone. The primary outcome measure was the development of new cytomegalovirus disease, either contralateral retinitis or biopsy-proved extraocular disease.

RESULTS

The incidence of new cytomegalovirus disease at six months was 44.3 percent in the group assigned to the ganciclovir implant plus placebo, as compared with 24.3 percent in the group assigned to the ganciclovir implant plus oral ganciclovir (P=0.002) and 19.6 percent in the group assigned to intravenous ganciclovir alone (P<0.001). As compared with placebo, oral ganciclovir reduced the overall risk of new cytomegalovirus disease by 37.6 percent over the one-year period of the study (P=0.02). However, in the subgroup of 103 patients who took protease inhibitors, the rates of new cytomegalovirus disease were low and of similar magnitude, regardless of treatment assignment. Progression of retinitis in the eye that initially received an implant was delayed by the addition of oral ganciclovir, as compared with placebo (P=0.03). Treatment with oral or intravenous ganciclovir reduced the risk of Kaposi's sarcoma by 75 percent (P=0.008) and 93 percent (P<0.001), respectively, as compared with placebo.

CONCLUSIONS

In patients with AIDS and cytomegalovirus retinitis, oral ganciclovir in conjunction with a ganciclovir implant reduces the incidence of new cytomegalovirus disease and delays progression of the retinitis. Treatment with oral or intravenous ganciclovir also reduces the risk of Kaposi's sarcoma.

A European evidence-based guideline for the prevention of type 2 diabetes

BACKGROUND

The prevalence and socioeconomic burden of type 2 diabetes (T2DM) and associated co-morbidities are rising worldwide.

AIMS

This guideline provides evidence-based recommendations for preventing T2DM.

METHODS

A European multidisciplinary consortium systematically reviewed the evidence on the effectiveness of screening and interventions for T2DM prevention using SIGN criteria.

RESULTS

Obesity and sedentary lifestyle are the main modifiable risk factors. Age and ethnicity are non-modifiable risk factors. Case-finding should follow a step-wise procedure using risk questionnaires and oral glucose tolerance testing. Persons with impaired glucose tolerance and/or fasting glucose are at high-risk and should be prioritized for intensive intervention. Interventions supporting lifestyle changes delay the onset of T2DM in high-risk adults (number-needed-to-treat: 6.4 over 1.8-4.6 years). These should be supported by inter-sectoral strategies that create health promoting environments. Sustained body weight reduction by >or= 5 % lowers risk. Currently metformin, acarbose and orlistat can be considered as second-line prevention options. The population approach should use organized measures to raise awareness and change lifestyle with specific approaches for adolescents, minorities and disadvantaged people. Interventions promoting lifestyle changes are more effective if they target both diet and physical activity, mobilize social support, involve the planned use of established behaviour change techniques, and provide frequent contacts. Cost-effectiveness analysis should take a societal perspective.

CONCLUSIONS

Prevention using lifestyle modifications in high-risk individuals is cost-effective and should be embedded in evaluated models of care. Effective prevention plans are predicated upon sustained government initiatives comprising advocacy, community support, fiscal and legislative changes, private sector engagement and continuous media communication.

An essential component of a novel bacterial protein export system with homologues in plastids and mitochondria

Proteins are transported across the bacterial plasma membrane and the chloroplast thylakoid membrane by means of protein translocases that recognize N-terminal targeting signals in their cognate substrates. Transport of many of these proteins involves the well defined Sec apparatus that operates in both membranes. We describe here the identification of a novel component of a bacterial Sec-independent translocase. The system probably functions in a similar manner to a Sec-independent translocase in the thylakoid membrane, and substrates for both systems bear a characteristic twin-arginine motif in the targeting peptide. The translocase component is encoded in Escherichia coli by an unassigned reading frame, yigU, disruption of which blocks the export of at least five twin-Arg-containing precursor proteins that are predicted to bind redox cofactors, and hence fold, prior to translocation. The Sec pathway remains unaffected in the deletion strain. The gene has been designated tatC (for twin-arginine translocation), and we show that homologous genes are present in a range of bacteria, plastids, and mitochondria. These findings suggest a central role for TatC-type proteins in the translocation of tightly folded proteins across a spectrum of biological membranes.

Valganciclovir results in improved oral absorption of ganciclovir in liver transplant recipients

The pharmacokinetics of an orally administered valine ester of ganciclovir (GCV), valganciclovir (VGC), were studied. These were compared to the pharmacokinetics of oral and intravenous GCV. Twenty-eight liver transplant recipients received, in an open-label random order with a 3- to 7-day washout, each of the following: 1 g of oral GCV three times a day; 450 mg of VGC per os (p.o.) once a day (q.d.); 900 mg of VGC p.o. q.d.; and 5 mg of intravenous (i.v.) GCV per kg of body weight q.d., given over 1 h. GCV and VGC concentrations were measured in blood over 24 h. One-sided equivalence testing was performed to test for noninferiority of 450 mg of VGC relative to oral GCV (two-sided 90% confidence interval [CI] > 80%) and nonsuperiority of 900 mg of VGC relative to i.v. GCV (two-sided 90% CI < 125%). The exposure of 450 mg of VGC (20.56 microg. h/ml) was found to be noninferior to that of oral GCV (20.15 microg. h/ml; 90% CI for relative bioavailability of 95 to 109%), and the exposure of 900 mg of VGC (42.69 microg. h/ml) was found to be nonsuperior to that of i.v. GCV (47.61 microg. h/ml; 90% CI = 83 to 97%). Oral VGC delivers systemic GCV exposure equivalent to that of standard oral GCV (at 450 mg) or i.v. GCV (at 900 mg of VGC). VGC has promise for effective CMV prophylaxis or treatment with once-daily oral dosing in transplant recipients.

Export of active green fluorescent protein to the periplasm by the twin-arginine translocase (Tat) pathway in Escherichia coli

The twin-arginine translocation (Tat) system targets cofactor-containing proteins across the Escherichia coli cytoplasmic membrane via distinct signal peptides bearing a twin-arginine motif. In this study, we have analysed the mechanism and capabilities of the E. coli Tat system using green fluorescent protein (GFP) fused to the twin-arginine signal peptide of TMAO reductase (TorA). Fractionation studies and fluorescence measurements demonstrate that GFP is exported to the periplasm where it is fully active. Export is almost totally blocked in tat deletion mutants, indicating that the observed export in wild-type cells occurs predominantly, if not exclusively, by the Tat pathway. Imaging studies reveal a halo of fluorescence in wild-type cells corresponding to the exported periplasmic form; the GFP is distributed uniformly throughout the cytoplasm in a tat mutant. Because previous work has shown GFP to be incapable of folding in the periplasm, we propose that GFP is exported in a fully folded, active state. These data also show for the first time that heterologous proteins can be exported in an active form by the Tat pathway.

Visual control of locomotion: Strategies for changing direction and for going over obstacles

Dynamics of gait adjustments required to go over obstacles and to alter direction of locomotion when cued visually were assessed through the measurement of ground reaction forces, muscle activity, and kinematics. The time of appearance of obstacles of varying heights, their position within the step cycle, and cue lights for direction change were varied. Direction change must be planned in the previous step to reduce the acceleration of the body center of mass toward the landing foot to 0. The inability of steering within the step cycle is due to the incapacity of muscles to rotate the body and translate it along the mediolateral axes. For obstacle avoidance, Ss systematically manipulated the gait patterns as a function of obstacle height and position and the time available within the ongoing step. Greater supraspinal involvement in control of locomotion is found.

DNAJC13 mutations in Parkinson disease

A Saskatchewan multi-incident family was clinically characterized with Parkinson disease (PD) and Lewy body pathology. PD segregates as an autosomal-dominant trait, which could not be ascribed to any known mutation. DNA from three affected members was subjected to exome sequencing. Genome alignment, variant annotation and comparative analyses were used to identify shared coding mutations. Sanger sequencing was performed within the extended family and ethnically matched controls. Subsequent genotyping was performed in a multi-ethnic case-control series consisting of 2928 patients and 2676 control subjects from Canada, Norway, Taiwan, Tunisia, and the USA. A novel mutation in receptor-mediated endocytosis 8/RME-8 (DNAJC13 p.Asn855Ser) was found to segregate with disease. Screening of cases and controls identified four additional patients with the mutation, of which two had familial parkinsonism. All carriers shared an ancestral DNAJC13 p.Asn855Ser haplotype and claimed Dutch-German-Russian Mennonite heritage. DNAJC13 regulates the dynamics of clathrin coats on early endosomes. Cellular analysis shows that the mutation confers a toxic gain-of-function and impairs endosomal transport. DNAJC13 immunoreactivity was also noted within Lewy body inclusions. In late-onset disease which is most reminiscent of idiopathic PD subtle deficits in endosomal receptor-sorting/recycling are highlighted by the discovery of pathogenic mutations VPS35, LRRK2 and now DNAJC13. With this latest discovery, and from a neuronal perspective, a temporal and functional ecology is emerging that connects synaptic exo- and endocytosis, vesicular trafficking, endosomal recycling and the endo-lysosomal degradative pathway. Molecular deficits in these processes are genetically linked to the phenotypic spectrum of parkinsonism associated with Lewy body pathology.

The bronchoconstrictor effect of inhaled prostaglandin D2 in normal and asthmatic men

Although prostaglandin D2 is the most abundant prostanoid generated by human lung mast cells and causes bronchoconstriction in animals, its effects have not been studied in human beings. We have compared the effects of inhaled prostaglandin D2 and prostaglandin F2 alpha on specific airway conductance in seven normal subjects and seven patients with mild allergic asthma. In dose-response studies in normal subjects, prostaglandin D2 caused a significant (20 +/- 6 per cent) fall in specific airway conductance after the two highest concentrations (250 and 500 micrograms per milliliter), whereas prostaglandin F2 alpha had no effect. In the asthmatic subjects, both prostaglandin D2 and prostaglandin F2 alpha caused a dose-related fall in specific airway conductance, starting at the lowest concentration of 4 micrograms per milliliter. Prostaglandin D2 was 3.5 times more potent than prostaglandin F2 alpha. In a single-dose study of both drugs (250 micrograms per milliliter), a minor fall in specific airway conductance occurred with prostaglandin D2 in the normal subjects, and a larger fall occurred with both drugs in the asthmatic subjects. Maximum effects were seen at three minutes: there was a 75 +/- 5 per cent fall with prostaglandin D2 and a 33 +/- 8 per cent fall with prostaglandin F2 alpha. These results suggest that prostaglandin D2 may be involved in the pathogenesis of bronchoconstriction in allergic asthma.

TatD is a cytoplasmic protein with DNase activity. No requirement for TatD family proteins in sec-independent protein export

The Escherichia coli Tat system mediates Sec-independent export of protein precursors bearing twin arginine signal peptides. Genes known to be involved in this process include tatA, tatB, and tatC that form an operon with a fourth gene, tatD. The tatD gene product has two homologues in E. coli coded by the unlinked ycfH and yjjV genes. An E. coli strain with in-frame chromosomal deletions in all three of tatD, ycfH, and yjjV exhibits no significant defect in the cellular location of five cofactor-containing enzymes that are synthesized with twin arginine signal peptides. Neither these mutations nor overproduction of the TatD protein cause any discernible effect on the export kinetics of an additional E. coli Tat pathway substrate. It is concluded that proteins of the TatD family have no obligate involvement in protein export by the Tat system. TatD is shown to be a cytoplasmic protein. TatD binds to immobilized Ni(2+) or Zn(2+) affinity columns and exhibits magnesium-dependent DNase activity. Features of the tatA operon that may control TatD expression are discussed.

Self-assembling peptide scaffolds promote enamel remineralization

Rationally designed beta-sheet-forming peptides that spontaneously form three-dimensional fibrillar scaffolds in response to specific environmental triggers may potentially be used in skeletal tissue engineering, including the treatment/prevention of dental caries, via bioactive surface groups. We hypothesized that infiltration of caries lesions with monomeric low-viscosity peptide solutions would be followed by in situ polymerization triggered by conditions of pH and ionic strength, providing a biomimetic scaffold capable of hydroxyapatite nucleation, promoting repair. Our aim was to determine the effect of an anionic peptide applied to caries-like lesions in human dental enamel under simulated intra-oral conditions of pH cycling. Peptide treatment significantly increased net mineral gain by the lesions, due to both increased remineralization and inhibition of demineralization over a five-day period. The assembled peptide was also capable of inducing hydroxyapatite nucleation de novo. The results suggest that self-assembling peptides may be useful in the modulation of mineral behavior during in situ dental tissue engineering.

TatB and TatC form a functional and structural unit of the twin-arginine translocase from Escherichia coli

In Escherichia coli, a subset of periplasmic proteins is exported via the twin-arginine translocation (Tat) pathway. In the present study, we have purified the Tat complex from E. coli, and we show that it contains only TatA, TatB, and TatC. Within the purified complex, TatB and TatC are present in a strict 1:1 ratio, suggesting a functional association. This has been confirmed by expression of a translational fusion between TatB and TatC. This Tat(BC) chimera supports efficient Tat-dependent export, indicating that TatB and TatC act as a unit in both structural and functional terms. The purified Tat complex contains varying levels of TatA, suggesting a gradual loss during isolation and a looser association. The molecular mass of the complex is approximately 600 kDa, demonstrating the presence of multiple copies of TatA, B, and C. Co-immunoprecipitation experiments show that TatC is required for the interaction of TatA with TatB, suggesting that TatA may interact with the complex via binding to TatC.

A new type of signal peptide: central role of a twin-arginine motif in transfer signals for the delta pH-dependent thylakoidal protein translocase

The delta pH-driven and Sec-related thylakoidal protein translocases recognise distinct types of thylakoid transfer signal, yet all transfer signals resemble bacterial signal peptides in structural terms. Comparison of known transfer signals reveals a single concrete difference: signals for the delta pH-dependent system contain a common twin-arginine motif immediately before the hydrophobic region. We show that this motif is critical for the delta pH-driven translocation process; substitution of the arg-arg by gln-gln or even arg-lys totally blocks translocation across the thylakoid membrane, and replacement by lys-arg reduces the rate of translocation by > 100-fold. The targeting information in this type of signal thus differs fundamentally from that of bacterial signal peptides, where the required positive charge can be supplied by any basic amino acid. Insertion of a twin-arg motif into a Sec-dependent substrate does not alter the pathway followed but reduces translocation efficiency, suggesting that the motif may also repel the Sec-type system. Other information must help to specify the choice of translocation mechanism, but this information is unlikely to reside in the hydrophobic region because substitution by a hydrophobic section from an integral membrane protein does not affect the translocation pathway.

Excessive production of reactive oxygen metabolites by inflamed colon: analysis by chemiluminescence probe

Reactive oxygen metabolites (ROMs) are involved in inflammatory diseases and are postulated to contribute to tissue injury in colitis. To determine whether excessive ROMs are generated by inflamed colonic mucosa and to identify possible sources and type of ROMs, mucosal ROMs were estimated in rats and humans using a chemiluminescence probe. Colitis was induced in rats by intracolonic injection of acetic acid or intraperitoneal injection of mitomycin C. Intact, inflamed colon in rats produced more ultraweak chemiluminescence than normal colon. Inflamed mucosal scrapings from both rat models produced significantly more luminol-enhanced chemiluminescence. Addition of catalase, an H2O2 scavenger, or azide, a myeloperoxidase inhibitor, into the media significantly decreased chemiluminescence from inflamed mucosal scrapings. Indomethacin, an antioxidant cyclo-oxygenase inhibitor, also decreased chemiluminescence, but MK-866, a 5-lipoxygenase inhibitor, had no effect. Colonic biopsy specimens obtained during colonoscopy from patients with ulcerative colitis also produced more catalase-inhibitable chemiluminescence than normal colonic mucosa. These data indicate that excessive ROMs are produced by inflamed colonic mucosa in both humans and rats, which may contribute to tissue injury.

Course in Parkinson disease subtypes: A 39-year clinicopathologic study

BACKGROUND

Individual variations in the course of Lewy body Parkinson disease (PD) are well known. Patients have been classified into different clinical subtypes to identify differences in the course among the subgroups. Several studies indicate that the outcome is more favorable in tremor dominant (TD) cases but others report no difference. A majority of progression studies are based on cross-sectional single point data or short-term clinical observations. The lack of longitudinally followed autopsy-confirmed PD cohort remains a major weakness in the literature. Biochemical studies of brain indicate most pronounced abnormalities in akinetic/rigid (AR) and the least in TD cases. We postulate that PD course in these subtypes is concordant with the biochemical findings.

OBJECTIVE

To compare the course in TD, mixed (MX), and AR subtypes of PD.

METHODS

Longitudinal clinical follow-up and autopsy studies were performed on 166 patients with PD over 39 years (1968-2006). Patients were classified into TD, AR, and MX based on the entire clinical course. Only the pathologically confirmed PD cases were included.

RESULTS

Sixty-six percent of cases had MX, 26% AR, and 8% TD profile. The age at onset was younger (p < 0.001) and progression to Hoehn & Yahr stage 4 was slower (p = 0.016) in the TD cases. Dementia was most common in AR (p = 0.039) and the least common in TD. In general, the course was most favorable in TD, followed by MX and AR subgroups.

CONCLUSION

The three subtypes of Parkinson disease have different courses which are concordant with the differences in brain biochemical abnormalities.

Prediction and assessment of the severity of post-operative pain and of satisfaction with management

A prospective observational study of cohorts of patients undergoing hip replacement (30), knee replacement (31), and spinal nerve root decompressive surgery (30) were interviewed pre-operatively to identify factors which might correlate with and potentially predict severe post-operative pain and dissatisfaction with analgesic management. The hip patients comprised 33% females and averaged 64 years, while the knee patients were 45% female and older (mean 71 years) and the spinal patients were 43% female and averaged 50 years. The three groups were similar with respect to all other pre-operative variables. Pain intensity was assessed mainly by self-report using the Present Pain Intensity (PPI) and Visual Analogue Scales (VAS) of the McGill Pain Questionnaire. The PPI was preferred by patients and nurses and, as there were no analytical advantages for the VAS, the PPI data are presented. The average post-operative pain during routine management mainly with patient controlled intravenous opiate, was mild to moderate and declined over days 1-5, declined further at discharge but rose slightly 1 month after discharge. The hip replacement patients experienced significantly (P < 0.01) less pain overall than the patients in the other two groups. Nurses' assessments of pain severity from observed behaviour were low and agreed poorly with the patients' self reports. Assessed on Likert Scales (0-6), the patients generally indicated good or excellent pain control, better than expected pain experience, and high levels of satisfaction with analgesic management. Significant (P < or = 0.01) multivariate correlates of severe post-operative pain assessed by logistic regression analysis of 11 variables were female gender, high pre-operative pain severity, and younger age. Significant (P < or = 0.01) multivariate correlates of both worse than expected pain experience and low satisfaction were female gender, high pre-operative pain severity, high anxiety about risks and problems, low expected pain severity, age (younger) and high willingness to report pain. These variables may reasonably be tested in further studies as potential predictors of adverse post-operative pain experience.

The transmembrane protein occludin of epithelial tight junctions is a functional target for serine peptidases from faecal pellets of Dermatophagoides pteronyssinus

There have been only a few studies of how allergens cross the airway epithelium to cause allergic sensitization. House dust mite fecal pellets (HDMFP) contain several proteolytic enzymes. Group 1 allergens are cysteine peptidases, whilst those of groups 3, 6 and 9 have catalytic sites indicative of enzymes that mechanistically behave as serine peptidases. We have previously shown that the group 1 allergen Der p 1 leads to cleavage of tight junctions (TJs), allowing allergen delivery to antigen presenting cells. In this study we determined whether HDMFP serine peptidases similarly compromise the airway epithelium by attacking TJs, desmosomes and adherens junctions. Experiments were performed in monolayers of MDCK, Calu-3 or 16HBE14o-epithelial cells. Cell junction morphology was examined by 2-photon molecular excitation microscopy and digital image analysis. Barrier function was measured as mannitol permeability. Cleavage of cell adhesion proteins was studied by immunoblotting and mass spectrometry. HDMFP serine peptidases led to a progressive cleavage of TJs and increased epithelial permeability. Desmosomal puncta became more concentrated. Cleavage of TJs involved proteolysis of the TJ proteins, occludin and ZO-1. This was associated with activation of intracellular proteolysis of ZO-1. In contrast to occludin, E-cadherin of adherens junctions was cleaved less extensively. Although Calu-3 and 16HBE14o-cells expressed tethered ligand receptors for serine peptidases, these were not responsible for transducing the changes in TJs. HDMFP serine peptidases cause cleavage of TJs. This study identifies a second general class of HDM peptidase capable of increasing epithelial permeability and thereby creating conditions that would favour transepithelial delivery of allergens.

The chemistry of enamel caries

The chemical changes which occur during the process of carious destruction of enamel are complex due to a number of factors. First, substituted hydroxyapatite, the main component of dental enamel, can behave in a very complex manner during dissolution. This is due not only to its ability to accept substituent ions but also to the wide range of calcium phosphate species which can form following dissolution. In addition, the composition, i.e., the extent of substitution, changes throughout enamel in the direction of carious attack, i.e., from surface to interior. Both surface and positively birefringent zones of the lesion clearly illustrate that carious destruction is not simple dissolution. Selective dissolution of soluble minerals occurs, and there is the probability of reprecipitation. The role of fluoride here is crucial in that not only does it protect enamel per se but also its presence in solution means that rather insoluble fluoridated species can form very easily, encouraging redeposition. The role of organic material clearly needs further investigation, but there is the real possibility of both inhibition of repair and facilitation of redeposition. For the future, delivering fluoride deep into the lesion would appear to offer the prospect of improved repair. This would entail a delivery vehicle which solved the problem of fluoride uptake by apatite at the tooth surface. Elucidation of the role of organic material may also reveal putative mechanisms for encouraging repair and/or protecting the enamel mineral.

Parkinsonism, Lrrk2 G2019S, and tau neuropathology

Lrrk2 G2019S is predominantly associated with alpha-synuclein-immunopositive Lewy body pathology. We have identified Family SK where Lrrk2 G2019S segregates with slowly progressive parkinsonism and the affected proband has tau-immunopositive neurofibrillary tangle pathology. Thus alpha-synucleinopathy and tauopathy, the predominant pathologies associated with parkinsonism, may be alternate outcomes of the same underlying genetic cause. Intriguingly, we observe no evidence of a direct interaction between either the tau or alpha-synuclein protein with Lrrk2.

The developing enamel matrix: nature and function

The hydroxyapatite crystals of mature enamel are unusually large, uniform and regularly disposed within the tissue, implying that their development is a highly controlled process. The organic matrix of developing enamel is presumed to play an important role in the modulation of mineral deposition and growth during tooth morphogenesis but the precise functions of individual matrix proteins remain unclear. The aim of this review was to survey the current knowledge of enamel matrix proteins with a view to suggesting possible functions. The organic matrix is highly heterogeneous, comprising proteins derived from a number of different genes, including amelogenin, enamelin, ameloblastin (amelin/sheathlin), tuftelin, dentine sialophosphoprotein, enzymes and serum proteins such as albumin. Each of these classes appears to undergo post-secretory sequential degradation which contributes further towards matrix heterogeneity. Possible functions of these proteins include de novo mineral nucleation/initiation (dentine sialophosphoprotein, tuftelin), mineral ion binding as crystal precursors (amelogenin, enamelin), control of crystal growth (amelogenin, enamelin, ameloblastin), support of growing crystals (amelogenin, enamelin), determination of prismatic structure (ameloblastin), cell signalling (tuftelin, ameloblastin), control of secretion (breakdown products) and protection of the mineral phase (amelogenin, enamelin). Failure of these mechanisms could lead to incomplete maturation of the enamel and the eruption of dysplastic tissue.

Predicting the risk of bacteremia in childen with fever and neutropenia

PURPOSE

We sought to identify factors assessable at the time of admission for fever and neutropenia that predict bacteremia in children with cancer.

PATIENTS AND METHODS

One hundred fifteen consecutive episodes of fever and absolute neutrophil count (ANC) less than 500/microliter in 72 children with cancer were studied prospectively to determine the risk of bacteremia using data assessable at the time of presentation. After exploratory analysis identified admission temperature and absolute monocyte count (AMoC) as the strongest predictive factors, recursive partitioning was used to determine cutpoints for these variables that resulted in discrimination between episodes associated with a lower or higher risk of bacteremia.

RESULTS

There were 24 episodes of bacteremia (21% of episodes). Episodes were grouped using the cutpoints for AMoC and temperature: 17% were classified as low risk for bacteremia (AMoC > or = 100/microliter), 65% as intermediate risk (AMoC < 100/microliter and temperature < 39.0 degrees C), and 18% as high risk (AMoC < 100/microliter and temperature > or = 39.0 degrees C). No episodes classified as low risk were associated with bacteremia; 19% of intermediate-risk and 48% of high-risk episodes were associated with bacteremia. The odds ratio of bacteremia for the high-risk versus the intermediate-risk group is 4.4 (95% confidence interval, 1.6 to 12.9). The risk classification was validated using data from 57 different episodes of fever and neutropenia treated in the same hospital.

CONCLUSION

Three levels of risk for bacteremia are defined using the AMoC and temperature at the time of admission for fever and neutropenia. Trials now should be conducted to test whether these factors may be used to assign some children to less intensive or outpatient antibiotic therapy at the time of presentation with fever and neutropenia.