Hydrogel oxygen reservoirs increase functional integration of neural stem cell grafts by meeting metabolic demands.

Injectable biomimetic hydrogels have great potential for use in regenerative medicine as cellular delivery vectors. However, they can suffer from issues relating to hypoxia, including poor cell survival, differentiation, and functional integration owing to the lack of an established vascular network. Here we engineer a hybrid myoglobin:peptide hydrogel that can concomitantly deliver stem cells and oxygen to the brain to support engraftment until vascularisation can occur naturally. We show that this hybrid hydrogel can modulate cell fate specification within progenitor cell grafts, resulting in a significant increase in neuronal differentiation. We find that the addition of myoglobin to the hydrogel results in more extensive innervation within the host tissue from the grafted cells, which is essential for neuronal replacement strategies to ensure functional synaptic connectivity. This approach could result in greater functional integration of stem cell-derived grafts for the treatment of neural injuries and diseases affecting the central and peripheral nervous systems.

Solid supported lipid membranes: new concepts for the biomimetic functionalization of solid surfaces.

Surface-layer (S-layer) supported lipid membranes on solid substrates are interfacial architectures mimicking the supramolecular principle of cell envelopes which have been optimized for billions of years of evolution in most extreme habitats. The authors implement this biological construction principle in a variety of layered supramolecular architectures consisting of a stabilizing protein monolayer and a functional phospholipid bilayer for the design and development of new types of solid-supported biomimetic membranes with a considerably extended stability and lifetime-compared to existing platforms-as required for novel types of bioanalytical sensors. First, Langmuir monolayers of lipids at the water/air interface are used as test beds for the characterization of different types of molecules which all interact with the lipid layers in various ways and, hence, are relevant for the control of the structure, stability, and function of supported membranes. As an example, the interaction of S-layer proteins from the bulk phase with a monolayer of a phospholipid synthetically conjugated with a secondary cell wall polymer (SCWP) was studied as a function of the packing density of the lipids in the monolayer. Furthermore, SCWPs were used as a new molecular construction element. The exploitation of a specific lectin-type bond between the N-terminal part of selected S-layer proteins and a variety of glycans allowed for the buildup of supramolecular assemblies and thus functional membranes with a further increased stability. Next, S-layer proteins were self-assembled and characterized by the surface-sensitive techniques, surface plasmon resonance spectroscopy and quartz crystal microbalance with dissipation monitoring. The substrates were either planar gold or silicon dioxide sensor surfaces. The assembly of S-layer proteins from solution to solid substrates could nicely be followed in-situ and in real time. As a next step toward S-layer supported bilayer membranes, the authors characterized various architectures based on lipid molecules that were modified by a flexible spacer separating the amphiphiles from the anchor group that allows for a covalent coupling of the lipid to a solid support, e.g., using thiols for Au substrates. Impedance spectroscopy confirmed the excellent charge barrier properties of these constructs with a high electrical resistance. Structural details of various types of these tethered bimolecular lipid membranes were studied by using neutron reflectometry. Finally, first attempts are reported to develop a code based on a SPICE network analysis program which is suitable for the quantitative analysis of the transient and steady-state currents passing through these membranes upon the application of a potential gradient.

Charge inversion at minute electrolyte concentrations.

Anionic dimyristoylphosphatidic acid monolayers spread on LaCl3 solutions reveal strong cation adsorption and a sharp transition to surface overcharging at unexpectedly low bulk salt concentrations. We determine the surface accumulation of La3+ with anomalous x-ray reflectivity and find that La3+ compensates the lipid surface charge by forming a Stern layer with approximately 1 La3+ ion per 3 lipids below a critical bulk concentration, ct approximately 500 nM. Above ct, the surface concentration of La3+ increases to a saturation level with approximately 1 La3+ per lipid, thus implying that the total electric charge of the La3+ exceeds the surface charge. This overcharge is observed at approximately 4 orders of magnitude lower concentration than predicted in ion-ion correlation theories. We suggest that transverse electrostatic correlations between mobile ions and surface charges (interfacial Bjerrum pairing) may contribute to the charge inversion.

Critical pediatric equipment availability in Canadian hospital emergency departments.

STUDY OBJECTIVE: Of all child visits to emergency departments, 1% to 5% involve critically ill children who require cardiopulmonary resuscitation. Numerous versions of pediatric equipment lists for EDs have been published. Despite these efforts, many EDs remain unprepared for pediatric emergencies. The objectives of this study were to assess the availability of pediatric resuscitation equipment items in Canadian hospital EDs and to identify risk factors for the unavailability of these items. METHODS: Using the updated database of the Canadian Association of Emergency Physicians (CAEP), a questionnaire survey was sent to 737 Canadian hospital EDs with a maximum of 3 mailings to nonresponders. On-site visits to a selected subset of hospital EDs were completed to validate the results obtained by the mailed questionnaire. RESULTS: The response rate was 88.3% (650/737). Results showed the following overall equipment unavailability: intraosseous needle, 15.9%; pediatric drug dose guidelines, 6.6%; infant blood pressure cuff, 14.8%; pediatric defibrillator paddles, 10.5%; infant warming device, 59.4%; infant bag-valve-mask device, 3.5%; infant laryngoscope blade, 3.5%; 3-mm endotracheal tube, 2.5%; and pediatric pulse oximeter, 18.0%. Low percentage of pediatric visits, lack of an on-call pediatrician for the ED, and lack of a pediatric advanced life support-trained physician on staff were independently associated with equipment unavailability. CONCLUSION: This study demonstrated that essential pediatric resuscitation equipment is unavailable in a disturbingly high number of EDs across Canada and has identified several determinants of this unavailability.

Urine culture from bag specimens in young children: are the risks too high?

OBJECTIVE: To compare the risks of contaminated culture results and consequent adverse clinical outcomes in urine specimens obtained by "clean-voided" bag method versus catheterization. STUDY DESIGN: Hospital-based cohort study of all children

Clinical decisionmaking based on venous versus capillary blood gas values in the well-perfused child.

STUDY OBJECTIVE: In children aged 1 month to 18 years, we sought to examine the correlation between venous and arterialized capillary blood gas values, and to determine whether the source of blood sample influenced the interpretation of the acid-base status and clinical management. METHODS: In a cross-sectional study, venous and capillary blood gas values were simultaneously obtained in acutely ill well-perfused patients treated in a pediatric emergency department. Intraclass correlation coefficients for capillary and venous measured gas values were calculated. Crude agreement and intraobserver concordance were calculated for responses of 2 intensivists to the interpretation and clinical management questions, based on capillary and venous gas results. RESULTS: Intraclass correlation coefficients for 78 capillary and venous paired measured gas values were.92 (pH), .80 (PCO 2 ), and .67 (PO 2 ). The alpha of concordance values between capillary and venous blood gas values, with 95% confidence intervals (CIs) were as follows, respectively, for physician A and B: interpretation, .61 (.47 to .73) and .48 (.41 to .55); need for bicarbonate,.85 (.73 to.97) and.80 (.72 to.88); and need for intubation .73 (.64 to .82), and .83 (.75 to .91). CONCLUSION: In the well-perfused patient, we believe that venous samples are an acceptable alternative to capillary blood samples for determination of blood gas values and for making clinical management decisions.

Survival and Activity of lux-Marked Aeromonas salmonicida in Seawater.

The fish pathogen Aeromonas salmonicida was chromosomally marked with genes encoding bacterial luciferase, luxAB, isolated from Vibrio fischeri, resulting in constitutive luciferase production. During exponential growth in liquid batch culture, luminescence was directly proportional to biomass concentration, and luminometry provided a lower detection limit of approximately 10(sup3) cells ml(sup-1), 1 order of magnitude more sensitive than enzyme-linked immunosorbent assay detection. In sterile seawater at 4(deg)C, lux-marked A. salmonicida entered a dormant, nonculturable state and population activity decreased rapidly. The activity per viable cell, however, increased by day 4, indicating that a proportion of the population remained active and culturable. Putative dormant cells were not resuscitated after the addition of a range of substrates.

Discrimination between Gyrodactylus salaris, G. derjavini and G. truttae (Platyhelminthes: Monogenea) using restriction fragment length polymorphisms and an oligonucleotide probe within the small subunit ribosomal RNA gene.

The small subunit ribosomal RNA (srRNA) gene was amplified from Gyrodactylus salaris using the polymerase chain reaction (PCR), cloned, and the complete gene sequence of 1966 bp determined. The V4 region of the srRNA gene was identified and amplified from single specimens of G. salaris, G. derjavini and G. truttae. Comparison of the V4 sequences from these three species revealed sequence differences from which restriction fragment length polymorphisms (RFLPs) were predicted and an oligonucleotide probe (GsV4) specific to G. salaris designed. Digestion of the amplified V4 region of the srRNA gene with Hae III and either Alw I, BstY I, Dde I or Mbo I provided a means of discriminating between G. salaris, G. derjavini and G. truttae. The GsV4 probe was used to detect the srRNA gene from G. salaris in Southern and dot blots of the amplified V4 region.

Diagnostic test ordering in the evaluation of febrile children. Physician and environmental factors.

OBJECTIVE: To assess the independent effects of physician and environmental factors on test ordering. METHODS: We prospectively studied 6191 consecutive visits by nonadmitted febrile (rectal temperature > or = 38.0 degrees C) children less than 18 years of age to a children's hospital emergency department from March through November 1989. Multiple logistic regression analysis was used to control for the mutually confounding effects of patient, physician, and environmental factors and to assess attending staff-trainee interactions (effect modification). RESULTS: Patients evaluated by hospital-based subspecialists were significantly more likely to undergo tests than patients evaluated by community-based physicians (odds ratio [OR] for undergoing at least one test, 1.13; 95% confidence interval [CI], 1.04 to 1.23; OR for complete blood cell count, 1.28; 95% CI, 1.12 to 1.46). Children seen by physicians with more than 10 years of experience were significantly less likely to undergo tests than those seen by their more junior colleagues, but this effect was modified substantially by trainee presence and level. For example, when children were seen by a physician with more than 10 years of experience and no trainee was involved, the OR for undergoing at least one test was 0.81 (95% CI, 0.73 to 0.91). If the same physician saw the same patient with a junior trainee, the OR for undergoing at least one test was 1.08 (95% CI, 0.95 to 1.24). Patients seen between July and November were significantly more likely to undergo at least one test than those seen between March and June (OR, 1.28; 95% CI, 1.20 to 1.36). CONCLUSIONS: Attending staff, trainee, and seasonal effects on test ordering have important implications for febrile children and their families, for clinical training and supervision, and for health care costs.

Worth vs Polarized four-dot test.

A direct comparison between the Worth four-dot (W4D) and Polarized four-dot (P4D) flashlights is reported in a randomized trial on 107 unselected patients greater than 2.5 years old. The primary outcome variable was the interpretable response rate. Secondary outcomes were response time and age of test failure. There were 29 patients who failed to complete the W4D test, but only 10 patients who could not complete the P4D test, giving interpretable response rates of 73% and 91%, respectively (p < .001). The P4D test was found to be less dissociative and easier to administer. It also had a higher detection rate for fusion. We recommend its use as a tool in the clinical evaluation of binocular sensorial states.

Cloning of the virulence regulatory (vir) locus of Bordetella pertussis and its expression in B. bronchiseptica.

Hybridisation with cosmid pRMB2, containing the vir locus of bordetella pertussis, showed that the Tn5 insertion in B. pertussis BP347 (Vir-) was located with 1 2.7 kB EcoRI fragment. When subcloned, this fragment alone was unable to complement BP347, but a larger 8.0 kb region which included the 2.7 kb EcoRI fragment, did restore expression of virulence associated properties to BP347, and to avirulent phase variants of both B. pertussis and B. bronchiseptica. EcoRI-digested DNA from stains of all four species of Bordetella showed homology to the cosmid genomic insert and to the 2.7 kb subclone, but B. avium showed a markedly different pattern of homology to the other species.

Characterization and chromosome assignment of the human homolog of int-2, a potential proto-oncogene.

int-2 is one of two cellular genes (int-1 and int-2) currently implicated in the genesis of mammary carcinomas by mouse mammary tumor virus and may constitute a novel cellular proto-oncogene. Using low-stringency hybridization with mouse int-2 probes, we established that homologous genes exist in a variety of mammalian species, including humans, but failed to detect related sequences in other classes and phyla. Recombinant bacteriophage clones and a single cosmid encompassing the human int-2 gene were isolated and characterized by restriction enzyme mapping. A survey of nine primary human breast tumors, three breast tumor cell lines, and three normal individuals revealed no evidence for gross amplification or rearrangement of the int-2 locus. Three distinct restriction fragment length polymorphisms were observed which could prove useful in future linkage studies. By a combination of in situ hybridization of metaphase chromosomes and somatic cell genetics, the human int-2 gene was mapped to chromosome 11, band q13.

Inappropriate use of antibiotics in croup at three types of hospital.

Despite recent suggestions that bacterial infection is an increasingly important cause of serious croup, most authorities still consider croup a viral disease in which antibiotic therapy is unnecessary. To assess the frequency of antibiotic use in croup among children in hospital, we reviewed the records at three types of hospital in Ontario. Children with evidence of a concurrent infection that might be bacterial were considered to have received antibiotics appropriately. Whereas only 6% of cases at a university-affiliated children's hospital were inappropriately treated with antibiotics, the proportions at a small rural community hospital staffed by general practitioners and a general hospital staffed by both pediatricians and general practitioners in a medium-sized city were 63% and 38%. Possible reasons for these differences are discussed.

Evidence that alveolar macrophages can synthesize and secrete alpha 1-antichymotrypsin.

Alpha 1-antichymotrypsin (alpha 1-AC) is a protein that inhibits chymotrypsinlike proteinases, such as leukocyte cathepsin G. It also inhibits cytotoxic "killer" cell activity in vitro and may therefore be important for the control of immunologic and inflammatory processes in the lung. Alpha 1-AC is present in lung secretions at high concentrations, suggesting local production within the lung. We investigated the possibility that alveolar macrophages may be capable of synthesizing and secreting alpha 1-AC. Human alveolar macrophages were cultured in the presence of L-75Se selenomethionine, and the culture supernatants were examined by immunoelectrophoresis followed by autoradiography. The results showed that the radio-amino acid was incorporated into alpha 1-AC, suggesting de novo synthesis of the protein. Cycloheximide inhibited incorporation of the label. Immunohistochemical staining of human lung tissue for alpha 1-AC showed the protein to be present within alveolar macrophages.

Stress fractures in rheumatoid arthritis.

Four cases of rheumatoid arthritis with a total of 12 undisplaced stress fractures of the lower extremities are described. Pain, swelling and disability arising from these fractures were initially mistaken for rheumatoid synovitis. Three patients had osteoporosis, and one had osteomalacia. A high index of suspicion is necessary in the diagnosis of these fractures. Radiographs and, if necessary, bone scans are indicated in rheumatoid patients presenting with spontaneous pain in the lower extremities in association with tenderness localized over the bone rather than the joint, particularly in the absence of other signs of rheumatoid activity.