Benchmarking a High-Fidelity Mixed-Species Entangling Gate.

We implement a two-qubit logic gate between a ^{43}Ca^{+} hyperfine qubit and a ^{88}Sr^{+} Zeeman qubit. For this pair of ion species, the S-P optical transitions are close enough that a single laser of wavelength 402 nm can be used to drive the gate but sufficiently well separated to give good spectral isolation and low photon scattering errors. We characterize the gate by full randomized benchmarking, gate set tomography, and Bell state analysis. The latter method gives a fidelity of 99.8(1)%, comparable to that of the best same-species gates and consistent with known sources of error.

Unemployment in an underserviced specialty?: The need for co-ordinated workforce planning in Canadian neurosurgery.

BACKGROUND: A recent report suggested that newly trained Canadian neurosurgeons are experiencing difficulty finding employment in Canada. Such occurrences, in combination with recent certification restrictions imposed in the US, have resulted in increasing concern that we will shortly be seeing a surplus of graduating neurosurgeons in Canada. The purpose of this study was to develop a better understanding of training and employment patterns in the Canadian neurosurgical workforce. METHODS: Using a database provided by the Royal College of Physicians and Surgeons of Canada, the current practice location of recent (1990-2002) neurosurgical certificants and a list of all neurosurgeons practicing in Canada were generated. From these data the number of surgeons per 100,000 patient population, and the number of residents required to maintain this workforce were determined. RESULTS: Practice location could be identified for 183/189 individuals who passed their qualifying examination in neurosurgery during this time. Only 45% of them are currently practicing in Canada. The current service ratio for this specialty is 0.65 per 100,000 population overall. Although 14.6 residents/year are being trained, only 6.5/year are required to maintain the existing neurosurgical workforce. CONCLUSIONS: Our data supports the concern about an imminent employment crisis for young neurosurgeons in Canada with more than twice the required number of residents being trained. However, this shortfall of staff positions is at a time when the specialty may be underservicing the country's population. These results highlight the necessity for more cohesive workforce planning in Canada, and in particular, ensuring the appropriate balance between training and need.

Maggots and wound healing: an investigation of the effects of secretions from Lucilia sericata larvae upon interactions between human dermal fibroblasts and extracellular matrix components.

BACKGROUND: Through clinical observation, Lucilia sericata (greenbottle fly) larvae are credited with exerting the following beneficial effects upon a chronic nonhealing wound: removal of necrotic tissue ('debridement'), disinfection of the wound and active promotion of granulation tissue formation. As a major cellular component of granulation tissue, fibroblasts play an extensive role in healing. The composition of extracellular matrix (ECM) located in the wound is another important factor, partaking in a dynamic feedback loop with the fibroblasts that produce it. Fibroblast-ECM interactions therefore exert considerable influence upon new tissue formation. OBJECTIVES: To investigate the effects of L. sericata larval excretory/secretory products (ES) upon the behaviour of fibroblasts, seeded upon ECM component surfaces. METHODS: ES were collected by washing freshly hatched larvae in phosphate-buffered saline. Human dermal neonatal fibroblast cells were seeded upon fibronectin- or collagen-coated surfaces, together with untreated (or 'native') ES, heat-treated ES, or no ES (ES blank). Following incubation, fibroblast adhesion was determined using an adenosine triphosphate assay and, for confirmation, a total nucleic acid content assay. Cell spreading was observed using microscopy. The effect of ES upon fibronectin structure was observed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Peptide sequencing of suspected fibronectin fragments was performed using an 'electrospray' type time of flight mass spectrometer and 'Peptident' database search. RESULTS: ES significantly reduced fibroblast adhesion to both fibronectin and, to a lesser extent, collagen. Cell spreading was also reduced, yet cells remained viable. For both spreading and adhesion, heat-treated ES exerted significantly less activity than native, untreated ES. However, they still exhibited significant activity when compared with the ES blank. ES appeared to modify fibroblast adhesion indirectly via proteolytic fragmentation of the fibronectin protein surface. CONCLUSIONS: L. sericata larval secretions modify fibroblast adhesion and spreading across ECM protein surfaces, while keeping cells viable. Proteolytic activity of the ES played a significant role. If transferred to the wound situation, such alteration of fibroblast-ECM interactions may enhance new tissue formation.

Degradation of extracellular matrix components by defined proteinases from the greenbottle larva Lucilia sericata used for the clinical debridement of non-healing wounds.

BACKGROUND: Larvae of the greenbottle fly Lucilia sericata are used routinely for the clinical treatment of difficult necrotic and infected wounds. Degradation by proteinases contained in larval excretory/secretory (ES) products is thought to contribute to wound debridement by removal of dead tissue. However, proteinase activity may also affect host tissue remodelling processes. OBJECTIVES: To identify proteolytic enzymes derived from L. sericata ES products with activities against fibrin and extracellular matrix (ECM) components. METHODS: Larval proteinase activities were assayed in vitro using class-specific substrates and inhibitors. Their action against fibrin and ECM components was examined using sodium dodecyl sulphate-polyacrylamide gel electrophoresis. RESULTS: Three classes of proteolytic enzyme were detected in the secretions using fluorescein isothiocyanate-labelled casein as a model substrate. The predominant activity belonged to serine proteinases (pH optima 8-9) of two different subclasses (trypsin-like and chymotrypsin-like), with a weaker aspartyl proteinase (pH 5) and a metalloproteinase (pH 9) with exopeptidase characteristics also present. Using skin-relevant ECM components as substrates L. sericata ES products solubilized fibrin clots and degraded fibronectin, laminin and acid-solubilized collagen types I and III. Hydrolysis of ECM macromolecules was inhibited by preincubating ES products with phenylmethylsulphonyl fluoride but not 4-amidinophenylmethylsulphonyl fluoride, indicating that degradation was due to the 'chymotrypsin-like' serine proteinase. CONCLUSIONS: These data suggest that a combination of L. sericata ES proteinases involving chymotrypsin-like and trypsin-like activities could potentially influence wound healing events when maggots are introduced into necrotic and infected wounds, with the chymotrypsin-like activity involved in the remodelling of ECM components.

The Buschke-Ollendorff syndrome presenting as familial elastic tissue naevi.

We present a family with Buschke-Ollendorff syndrome presenting as elastic tissue naevi without evidence of osteopoikilosis. We discuss the variable expression of this syndrome in other families previously reported in the literature, the association of various connective tissue abnormalities and their correlation with the pathogenesis of this interesting condition.

Alzheimer's disease associated presenilin 1 interacts with HC5 and ZETA, subunits of the catalytic 20S proteasome.

Proteolytic processing and degradation tightly regulate the amount of stable, functional presenilin 1 (PSEN1) in the cell. The approximately 46-kDa PSEN1 holoprotein is cleaved into a approximately 30-kDa N-terminal fragment (NTF) and a approximately 20-kDa C-terminal fragment (CTF) by an unknown protease. The fragments are stabilized in a high molecular weight complex and nonincorporated fragments and excess holoprotein are degraded by the 26S proteasome. The tight balance between, on the one hand, processing and incorporation into the stable complex and, on the other hand, proteolytic degradation of excess PSEN1, indicates that minor changes in one of these two processes could be pathologically relevant. Here we demonstrate the direct physical interaction between PSEN1 and two subunits, HC5 and ZETA, of the 20S proteasome. These interactions were identified using an interaction trap screening and were further established in an in vitro binding assay. Furthermore, we were able to coimmunoprecipitate the transfected binding partners, as well as the endogenous PSEN1 and ZETA proteins from HEK 293T cells. Finally, degradation of ubiquitinated wild-type and mutant PSEN1 by the 26S proteasome was demonstrated. In conclusion, we report a direct interaction between PSEN1 and subunits of the 20S catalytic particle of the 26S proteasome, further establishing the involvement of proteasomal degradation in the regulation of PSEN1 turnover.

Experimental AA amyloidogenesis is associated with differential expression of extracellular matrix genes.

An abnormality in basement membrane metabolism has been postulated to play an important role in the pathogenesis of experimental murine AA amyloidosis. The potential contribution of the structural basement membrane proteins laminin, type IV collagen and entactin to amyloidogenesis in this model was investigated with a kinetic analysis of the expression of the corresponding genes during amyloid formation. Splenic AA amyloid deposition was stimulated by the concomitant administration of subcutaneous silver nitrate, as an inflammatory stimulus, and intravenous amyloid enhancing factor. Using a reverse transcription-polymerase chain reaction assay, a differential pattern of expression of these genes was observed at the mRNA level. Whereas laminin B1 mRNA levels did not change at any time during amyloidogenesis, a 2.2 to 3 fold induction of laminin B2, entactin and alpha 1-type IV collagen mRNAs coincided with the initial detection of splenic amyloid deposits at 48 hours post-stimulation, as detected by immunohistochemistry. Temporal and spatial codeposition of laminin and type IV collagen with amyloid was demonstrated by immunohistochemistry. A 1.4, 2.3 and 2.2-fold increase in laminin B2, entactin and alpha 1-type IV collagen mRNA levels, respectively, was detected at 24 hours post-stimulation, a point at which amyloid deposits could not be detected. Neither inflammation nor amyloid enhancing factor alone influenced laminin, entactin or type IV collagen expression at the protein or mRNA level. These observations suggest that the laminin B2 chain and alpha 1-type IV collagen chain account, at least in part, for the observed laminin and collagen IV immunoreactivity in AA amyloid deposits and that entactin may also be a component of the amyloid deposit. The onset of the induction of laminin B2, entactin and alpha 1-type IV collagen gene expression prior to the appearance of amyloid deposits, and our previous data with the heparan sulfate proteoglycan, perlecan, suggests these basement membrane proteins may play a role in the initial stages of AA fibrillogenesis.

Identification of a Drosophila presenilin homologue: evidence of alternatively spliced forms.

Some cases of Alzheimer's disease are inherited as a dominant trait in humans. To date, mutations in three genes account for some of them: the amyloid precursor protein (APP) and presenilins 1 and 2 (PS-1 and PS-2, respectively). The function of the presenilins is still unclear, although they belong to a transmembrane protein-gene family, probably involved in some signaling pathway. We report here the isolation of the Drosophila presenilin homologue using the human PS-1 and PS-2 cDNAs as probes. Only one single gene has been detected in the Drosophila genome and evidence for alternatively spliced forms is presented and compared to the isoforms reported in humans. Temporal and spatial expression has been assessed by Northern blot and in situ hybridization on embryos of different developmental stages.

Immunoreactivity of presenilin-1 and tau in Alzheimer's disease brain.

Mutations in the presenilin-1 gene (PS-1) on chromosome 14 are causative for early-onset familial Alzheimer's disease (AD). In order to study the localization of PS-1 in human brain, a polyclonal antibody, SB63, against a N-terminal epitope of PS-1 (25VRSQNDNRERQEHND40), was raised in rabbits and characterized. Immunolabeling with SB63 of formalin-fixed sections of hippocampus from cases of PS-1-linked AD (PS-1 I143T (AD/A), G384A (AD/B)), sporadic AD, and controls showed a predominant neuronal staining pattern with a stronger immunoreactivity in pyramidal neurons. Staining was mainly granular and localized in the neuronal cell body as well as in neuronal processes. In AD some dystrophic neurites surrounding the amyloid plaques were stained, but no immunoreactivity was observed in the amyloid core. Although PS-1 was present in tangle bearing neurons, colocalization of PS-1 and tau could not be detected using immunofluorescence double labeling. Our data indicate that the pattern of PS-1 immunoreactivity in the hippocampus does not substantially differ between PS-1-linked AD, sporadic AD, and controls.

Painful piezogenic pedal papules: response to local electro-acupuncture.

We report the case of a woman who had pain in both heels which was exacerbated by long periods of exercise. On examination, there were small flesh-coloured papules which appeared over the medial and lateral aspects of the heels only on weight bearing. Coincidentally, she was noted to have larger flesh-coloured papules over the anterior surface of the shins. The diagnoses of painful piezogenic pedal papules and bilateral tibialis anterior muscle herniation, respectively, were made. After many attempts to control the pain, a course of electro-acupuncture was commenced. A good subjective clinical response was achieved which has been maintained by fortnightly treatments. We discuss the prevalence, pathogenesis and treatment of painful piezogenic pedal papules. We believe that our patient is the first to have 'herniations' at both heel and shin sites and the first to have successful sustained pain relief for painful piezogenic pedal papules.

Prediction of murine MHC class I epitopes in a major house dust mite allergen and induction of T1-type CD8+ T cell responses.

The group I (Der p 1) allergen of Dermatophagoides pteronyssinus (house dust mite, HDM) contains several T helper (Th) epitopes recognized by C57BL/6 mice, with the peptide (111-139) containing a dominant MHC class II-restricted epitope (113-127). Since CD8+ T cells are thought to play a role in the regulation of allergic disease, we examined the Der p 1 sequence for potential MHC class I-binding motifs and observed that residues 111-119 (FGISNYCQI) contain motifs for H-2Db and Kb. Furthermore, immunization of C57BL/6 mice with unadjuvanted Ty virus-like particles (VLP) carrying Der p 1 (111-139), a method known to induce murine cytotoxic T lymphocyte (CTL) responses, primed Der p 1 (111-119)-specific Db-restricted CTL which produce high levels of IFN-gamma and low levels of IL-5 and IL-6 in vitro (T1-type CTL). VLP carrying the minimal epitope (FGISNYCQI) also induced a CTL response following immunization without adjuvant by various routes. Der p 1 (111-139)-VLP adjuvanted with alum did not prime CTL in C57BL/6 mice but were found to prime Th1-type CD4+ T cells that recognize the overlapping peptide (113-127) and native protein. The ability to successfully predict allergen-specific CD8+ T cell epitopes and prime CD8+ and/or CD4+ T cell responses provides an opportunity to dissect the relative roles of these T cells in the regulation of allergic responses and may offer therapeutic potential for reprogramming Th2-type allergic responses.

Enlarging congenital haemangioma in an adult--a new entity?

We report the case of a 39-year-old woman with a persistent congenital vascular lesion, which unusually is continuing to enlarge. Histologically, the lesion is a thin-walled haemangioma with numerous mast cells. Currently, the precise mechanism of vessel proliferation in such lesions is unknown, but it is important in the pathogenesis of both haemangiomas and other dermatological conditions, as well as in wound healing and the formation of tumour metastases. We discuss various angiogenic factors with particular reference to the putative role of the mast cell in the pathogenesis of haemangiomas.

Sweet's syndrome in association with non-Hodgkin's lymphoma.

Sweet's syndrome is an acute neutrophilic dermatosis frequently found in association with other conditions, particularly inflammatory and neoplastic disease. We report here a patient who developed the condition 2 years after the diagnosis of non-Hodgkin's lymphoma (NHL), in this case affecting a tonsil, the thirteenth report of such an association. We discuss the diagnosis, investigation and management of Sweet's syndrome in the context of the current case.

Mycosis fungoides with spontaneously regressing CD30-positive tumorous lesions.

Mycosis fungoides (MF) is the most common cutaneous T-cell lymphoma. We report a case in which identical T-cell clones were identified in both patch and tumour stage lesions and in which the tumorous deposits, containing CD30-positive cells, regressed spontaneously. We discuss the differential diagnosis of the tumorous lesions and the spectrum of CD30-positive proliferative T-cell disorders.