Biological recognition of graphene nanoflakes.

The systematic study of nanoparticle-biological interactions requires particles to be reproducibly dispersed in relevant fluids along with further development in the identification of biologically relevant structural details at the materials-biology interface. Here, we develop a biocompatible long-term colloidally stable water dispersion of few-layered graphene nanoflakes in the biological exposure medium in which it will be studied. We also report the study of the orientation and functionality of key proteins of interest in the biolayer (corona) that are believed to mediate most of the early biological interactions. The evidence accumulated shows that graphene nanoflakes are rich in effective apolipoprotein A-I presentation, and we are able to map specific functional epitopes located in the C-terminal portion that are known to mediate the binding of high-density lipoprotein to binding sites in receptors that are abundant in the liver. This could suggest a way of connecting the materials' properties to the biological outcomes.

The analgesic and anti-inflammatory effects of Salvinorin A analogue ß-tetrahydropyran Salvinorin B in mice.

BACKGROUND: Drugs activating the mu opioid receptor are routinely used to treat severe acute and chronic pain. Unfortunately, side effects including nausea, constipation, respiratory depression, addiction and tolerance can limit clinical utility. In contrast, kappa opioid receptor (KOPr) agonists, such as Salvinorin A (SalA), have analgesic properties with little potential for abuse. METHODS: We evaluated SalA and the novel analogue ß-tetrahydropyran Salvinorin B (ß-THP SalB) for the ability to modulate pain and inflammation in vivo. The hot water tail-withdrawal assay, intradermal formalin-induced inflammatory pain and paclitaxel-induced neuropathic pain models were used to evaluate analgesic properties in mice. Tissue infiltration of inflammatory cells was measured by histology and flow cytometry. RESULTS: ß-tetrahydropyran Salvinorin B produced a longer duration of action in the tail-withdrawal assay compared to the parent compound SalA, and, like SalA and U50,488, ß-THP SalB is a full agonist at the KOPr. In the formalin-induced inflammatory pain model, ß-THP SalB and SalA significantly reduced pain score, paw oedema and limited the infiltration of neutrophils into the inflamed tissue. ß-THP SalB and SalA supressed both mechanical and cold allodynia in the paclitaxel-induced neuropathic pain model, in a dose-dependent manner. CONCLUSIONS: Structural modification of SalA at the C-2 position alters its analgesic potency and efficacy in vivo. Substitution with a tetrahydropyran group at C-2 produced potent analgesic and anti-inflammatory effects, including a reduction in paclitaxel-induced neuropathic pain. This study highlights the potential for KOPr agonists as analgesics with anti-inflammatory action and little risk of abuse. SIGNIFICANCE: Salvinorin A and the novel analogue ß-THP Salvinorin B show analgesic effects in the tail-withdrawal and formalin assays. They reduce oedema and decrease neutrophil infiltration into inflamed tissue, and suppress mechanical and cold allodynia in paclitaxel-induced neuropathic pain.

Increased function of pronociceptive TRPV1 at the level of the joint in a rat model of osteoarthritis pain.

OBJECTIVES: Blockade of transient receptor potential vanilloid 1 (TRPV1) with systemic antagonists attenuates osteoarthritis (OA) pain behaviour in rat models, but on-target-mediated hyperthermia has halted clinical trials. The present study investigated the potential for targeting TRPV1 receptors within the OA joint in order to produce analgesia. METHODS: The presence of TRPV1 receptors in human synovium was detected using western blotting and immunohistochemistry. In a rat model of OA, joint levels of an endogenous ligand for TRPV1, 12-hydroxy-eicosatetraenoic acid (12-HETE), were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Effects of peripheral administration of the TRPV1 receptor antagonist JNJ-17203212 on afferent fibre activity, pain behaviour and core body temperature were investigated. Effects of a spinal administration of JNJ-17203212 on dorsal horn neuronal responses were studied. RESULTS: We demonstrate increased TRPV1 immunoreactivity in human OA synovium, confirming the diseased joint as a potential therapeutic target for TRPV1-mediated analgesia. In a model of OA pain, we report increased joint levels of 12-HETE, and the sensitisation of joint afferent neurones to mechanical stimulation of the knee. Local administration of JNJ-17203212 reversed this sensitisation of joint afferents and inhibited pain behaviour (weight-bearing asymmetry), to a comparable extent as systemic JNJ-17203212, in this model of OA pain, but did not alter core body temperature. There was no evidence for increased TRPV1 function in the spinal cord in this model of OA pain. CONCLUSIONS: Our data provide a clinical and mechanistic rationale for the future investigation of the therapeutic benefits of intra-articular administration of TRPV1 antagonists for the treatment of OA pain.

Metabolic responses to exhaustive exercise change markedly during the protracted non-trophic spawning migration of the lamprey Geotria australis.

Adults of the Southern hemisphere lamprey Geotria australis were subjected to an exercise/recovery regime at the commencement and end of their 12-15 month non-trophic, upstream spawning migration. In early (immature) migrants and pre-spawning females, muscle glycogen was markedly depleted during exercise, but became rapidly replenished. As muscle lactate rose during exercise and peaked 1-1.5 h into the recovery period, and therefore after muscle glycogen had become replenished, it cannot be the direct source for that replenishment. However, both plasma lactate and glycerol (but not muscle glycerol and glucose) rose sharply during exercise and then declined markedly during the first 0.5 h of recovery and thus exhibited the opposite trend to that of muscle glycogen, implying that these limited pools of glycogenic precursors contribute to glycogen replenishment. Although plasma glucose rose following exercise, and consequently could also be a precursor for muscle glycogen replenishment, it remained elevated even after muscle glycogen had become replenished. While resting pre-spawning females and mature males retained high muscle glycogen concentrations, this energy store became permanently depleted in females during spawning. In mature males, muscle glycogen remained high and lactate low during the exercise/recovery regime, whereas muscle glycerol declined precipitously during exercise and then rose rapidly. In summary, vigorous activity by G. australis is fuelled extensively by anaerobic metabolism of glycogen early in the spawning run and by pre-spawning females, but by aerobic metabolism of its energy reserves in mature males.

Muscle glycogen, lactate and glycerol-3-phosphate concentrations of larval and young adult lampreys in response to exercise.

When stimulated, the ammocoetes (larvae) of Geotria australis swim continuously at a moderate rate for only approximately 20 min, whereas the downstream migrants (young adults) of this species did not become exhausted following similar swimming activity over the same period. Mean concentrations of muscle glycogen in ammocoetes declined during exercise, but returned to resting levels within 30 min of recovery, whereas those in young adults changed little during the corresponding periods. Moreover, muscle lactate concentrations of ammocoetes rose markedly during exercise and the first 30 min of recovery, before declining significantly, while those of young adults remained similar during and immediately after exercise. Calculations, using the glycogen and lactate concentrations immediately after exercise, suggest that during exercise glycogen is, to some extent, utilised anaerobically (approx. 24%) by ammocoetes, but only aerobically by young adults. Furthermore, since young adults used only a small amount of glycogen, they presumably metabolised triacylglycerol aerobically to produce energy. Muscle glycerol-3-phosphate levels were far higher prior to and immediately after exercise in downstream migrants than in ammocoetes and then declined precipitously. The above trends in muscle glycogen and lactate of larval G. australis parallels, to some degree, those recorded by other workers for upstream migrant Petromyzon marinus that had been exercised to exhaustion.

The treatment of choroidal melanoma with 198 Au plaque brachytherapy.

BACKGROUND: Seventy-nine consecutive patients with primary choroidal melanoma were treated with 198 Au plaque brachytherapy at the British Columbia Cancer Agency (BCCA) between 1992 and 1998 with perioperative ultrasound to confirm plaque placement. Seventy-seven of the 79 patients were analyzable for this study. RESULTS: Five year actuarial disease specific survival, enucleation free survival, and local control are 95, 94, and 98%, respectively. There were four melanoma related deaths, all secondary to liver metastases. CONCLUSIONS: The BCCA experience in selected patients with choroidal melanomas treated with 198Au plaque brachytherapy has resulted in excellent survival and local control with minimal significant toxicity while preserving the globe. Our results using 198 Au seeds are comparable to other series using 125I, 60Co, and 106Ru at other centers.

Use of the polymerase chain reaction to detect B- and T-cell gene rearrangements in vitreous specimens from patients with intraocular lymphoma.

OBJECTIVE: To determine whether the polymerase chain reaction for B- and T-cell gene rearrangements could be applied to vitreous specimens to aid in the diagnosis of intraocular lymphoma. METHODS: Vitreous washing specimens from 4 patients were received in balanced saline solution and centrifuged, and a portion of the pellet was used to make routine cytospins. The remainder was used to make a crude extract of DNA that was amplified for immunoglobulin heavy chain and T-cell receptor gamma gene rearrangements and the 14;18 translocation by polymerase chain reaction. RESULTS: One patient had 2 specimens 2 years apart. In each, there was an identical band corresponding to the minor cluster region breakpoint of the bcl-2 oncogene, indicating the presence of a 14;18 translocation. One patient showed an immunoglobulin heavy chain gene rearrangement indicating a B-cell lymphoma. Two patients showed rearrangements of the T-cell receptor gamma gene, indicating the presence of a T-cell lymphoma. CONCLUSIONS AND CLINICAL RELEVANCE: Vitreous washing specimens can be used successfully to detect B- and T-cell gene rearrangements by polymerase chain reaction. This may be useful to confirm the diagnosis of intraocular large cell lymphoma in cases suggestive of the diagnosis. Prompt handling of the specimens is necessary to prevent degradation of the DNA.

An epidemiologic investigation of unexpected refractive errors following cataract surgery.

OBJECTIVE: To determine the extent and magnitude of unexpected refractive errors following cataract surgery with intraocular lens (IOL) implantation and to determine what characteristics were associated with the errors. DESIGN: In this nonconcurrent prospective study, preoperative, intraoperative and postoperative information was collected from the charts of the 523 consecutive patients who underwent cataract extraction and polymethylmethacrylate IOL implantation performed by one of nine participating surgeons between Jan. 1 and Apr. 30, 1995, or the same dates in 1996. SETTING: University-affiliated eye care centre in Vancouver. OUTCOME MEASURE: Postoperative excess correction, calculated for each patient by subtracting the actual postoperative spherical equivalent from the expected spherical equivalent. Eyes with an excess correction of more than 1.00 dioptre were considered "overcorrected." RESULTS: Univariate analysis showed that the formula used to calculate the lens power, axial length, year of surgery, A-constant/surgeon factor used and lens manufacturer were associated with overcorrection. In a logistic regression model, lens manufacturer was the only variable independently associated with overcorrection. CONCLUSIONS: Routine reporting and follow-up is necessary to identify this kind of "outbreak" and the associated factors. The current guidelines of the Health Protection Branch, Health Canada, for evaluation of IOLs that have changed manufacturers are not adequate to identify the kind of error that we detected.

Preferential germline mutation of the paternal allele in retinoblastoma.

The event triggering malignant proliferation in 70% of retinoblastoma tumours is loss of heterozygosity for chromosome 13q14, whereby the normal retinoblastoma gene (RB1) allele is lost and an already mutated RB1 allele remains in the tumour. The first allele suffers a mutational event--deletion, duplication or point mutation (manuscript in preparation)--either in the germ line (all bilateral patients) or in a somatic retinal cell (most unilateral patients). Most bilateral patients have no family history of retinoblastoma and are presumed to have new germline mutations which arose in the egg, sperm or early embryo. We have determined the parental origin of the retained allele in nine retinoblastoma tumours from eight unrelated non-familial cases by using RB1-linked genetic markers. Six tumours retained the paternal allele and three retained the maternal allele. Of the three unilateral tumours, only one retained the paternal RB1 allele. Thus, there is no evidence that the paternal RB1 allele is preferentially retained in retinoblastoma, as has been suggested to be the case in osteosarcoma. By contrast, tumours from four of the five bilateral patients retained the paternal RB1 allele. This suggests either that new germline RB1 mutations arise more frequently during spermatogenesis than during oogenesis, or that imprinting in the early embryo affects chromosomal susceptibility to mutation.

Measurement of striated muscle fibre diameters using interactive computer-aided microscopy.

We have measured muscle fibre diameters using two methods of interactive computer-aided microscopy. They are simple to perform, reproducible and more convenient than manual methods of measurement. The technique is of general application to histological measurement.

Measurement in jejunal biopsies by computer-aided microscopy.

A method of morphometric analysis of jejunal mucosa using computer-aided microscopy is described. It is based on the technique of interactive computer graphics with definition by the observer of areas and lengths for measurement, but it also includes automatic measurements based on grey-level segmentation. The analyses are performed rapidly and efficiently. The technique is applicable to the analysis of biopsy tissue from many sites.

Signal to noise enhancement in a study of cell wall structure of Bacillus subtilis by interactive computation.

This paper describes a technique for obtaining values of the width and variation in optical density of sectioned bacterial cell walls by interactive computational methods. Background 'noise' prevents accurate determination of cell wall boundaries from the data in a single scan line but the noise may be suppressed by averaging several consecutive scan lines. although application of the technique is explained for sectioned bacterial cell walls, it is equally valid for similar situations where single line scans of electron micrographs are inadequate for precise determination of measurement.

Reading chest radiographs for pneumoconiosis by computer.

Computer programs for measuring simple pneumoconiosis in radiographs are described and assessed. The 36 films studied had been read by 11 skilled human observers and a 'radiological score' of pneumoconiotic severity was therefore available for each film. The computer assigns to each square grid of side 3-6 mm a measure which reflects the unevenness of the density distribution in that grid. The 'computed score' is defined as the mean diversity over all relevant grids in both lung fields. On the set of 36 films the correlation between radiological score and computed score was 0-88. By contrast, the correlation between the score assigned by a single observer and the average of the scores assigned by the other 10 was in the range 0-95 to 0-98. The program can use the computed score to classify a film into one of the four major International Labour Office (ILO) U/C categories, the success rate of this process being 80% compared with those quoted by other workers in the range 45%-65%. If the films used in this study be typical, then the program described may form the basis of an automatic method for measuring pneumoconiosis in epidemiological work.