Biomedical subjects
P Bartlett
Publications and source records attributed to P Bartlett.
Superlattice formation in mixtures of hard-sphere colloids
We report a detailed experimental study of the superlattice structures formed in dense binary mixtures of hard-sphere colloids. The phase diagrams observed depend sensitively on the ratio alpha=R(S)/R(L) of the radii of the small (S) and large (L) components. Mixtures of size ratio alpha=0.72, 0.52, 0.42, and 0.39 are studied. The structures of the colloidal phases formed were identified using a combination of light-scattering techniques and confocal fluorescent microscopy. At alpha=0.39, ordered binary crystals are formed in suspensions containing an equal number of large and small spheres which microscopy shows have a three-dimensional structure similar to either NaCl or NiAs. At the larger size ratio, alpha=0.52, we observe LS2 and LS13 superlattices, isostructural to the molecular compounds AlB2 and NaZn13, while at alpha=0.72 the two components are immiscible in the solid state and no superlattice structures are found. These experimental observations are compared with the predictions of Monte Carlo simulations and cell model theories.
Penstrep clarification.
Explore the source record for details and available documents.
The asylum, the workhouse, and the voice of the insane poor in 19th-century England.
Explore the source record for details and available documents.
Radiologic versus surgical placement of vena cava filters: a comparative study of cost, time and complications.
OBJECTIVE: To compare the cost- and time-effectiveness of 2 methods of placement of vena cava filters for the prevention of pulmonary embolism: the radiologic percutaneous placement of the Vena Tech LGM filter and the surgical cutdown placement of the 24 Fr Greenfield filter. METHODS: Retrospective review of radiologic and clinical records for 15 consecutive patients who had the Vena Tech LGM filter placed radiologically and 15 consecutive patients who had the Greenfield filter placed surgically. Factors studied were cost, procedure time, waiting time and rates of immediate and delayed complications. The follow-up period ranged from 1 to 26 months (mean 7 months). RESULTS: The procedure cost for the radiologic method was $702 less than for the surgical method. The procedure time for the radiologic method was 30 minutes shorter, and the waiting time for placement was also shorter. There was no difference in the complication rates following each procedure. The higher cost of the Greenfield filter accounted for 80% of the total cost difference. CONCLUSION: The radiologic percutaneous method of filter placement is preferred over the surgical cutdown method because of its benefits in terms of cost and time with no increase in risk. However, when the difference in cost between filters is taken into account, there is little difference in overall costs for the 2 methods. Therefore, radiology and surgery departments can place a filter percutaneously at a similar cost. Other factors such as waiting times, complication rates, venography capabilities and physician interest in performing the procedure will dictate which department places the filter.
Cytokines which signal through the LIF receptor and their actions in the nervous system.
A number of different cytokines, each initially characterized on the basis of very different biological activities, all have very similar signalling pathways and share a similar tertiary structure. These cytokines include leukaemia inhibitory factor, ciliary neuronotrophic factor, oncostatin M, growth-promoting activity and cardiotrophin 1. They all have been found to regulate a number of properties of cells of the developing and mature nervous system in vitro and thus are neuroregulatory cytokines. The actions of these cytokines include regulation of neurotransmitter phenotype, differentiation of neuronal precursor cells both in the peripheral nervous system and in the spinal cord, survival of differentiated neurons, and regulation of development of both astrocytes and oligodendrocytes. In addition, studies in animal models show that these factors can rescue sensory and motor neurons from axotomy-induced cell death, which suggests that they can act as trauma factors for injured neurons. Analysis of the expression patterns of the different neuroregulatory cytokines and their receptors reveals that the receptors are expressed throughout nervous system development and following trauma, whereas the cytokines show temporal and spatial specific expression patterns. This is consistent with the idea that specific cytokines have specific roles in neural development and repair, but that their signalling pathways are shared. The phenotypes of the receptor knockouts show clear deficits in nervous system development, indicating a crucial role for LIF receptor signalling. Knockouts of individual cytokines are less dramatic, but LIF and CNTF knockouts do reveal deficits in maintenance of motor neurons or following trauma. Thus, whereas LIF and CNTF have clear roles in maintenance and following trauma, it is unclear which of the cytokines is involved in nervous system development. In clinical terms, these findings add further support to the use of these cytokines in nervous system trauma and disease.
Measurement of hippocampal T2 in epilepsy.
Explore the source record for details and available documents.
Leukemia inhibitory factor and ciliary neurotrophic factor in sensory neuron development.
Leukemia inhibitory factor (LIF), ciliary neurotrophic factor (CNTF), and related proteins are potentially involved in several aspects of sensory neuron development. There is evidence that LIF promotes the differentiation of sensory neurons from progenitor cells of neural crest origin. Later in development, LIF, CNTF, oncostatin M and interleukin-6 promote the survival of cultured neurons. Some neurons, like those of the nodose ganglion, respond early in their development to these factors, whereas other neurons, like those of the trigeminal ganglion, respond much later. In addition to promoting sensory neuron survival, there is some evidence that LIF is able to influence neurotransmitter and neuropeptide expression in these neurons. These observations suggest that several kinds of sensory neurons may be influenced in various ways by LIF and related factors at different stages of their development.
Role of leukaemia inhibitory factor (LIF) in rat peripheral nerve regeneration.
The cytokine leukaemia inhibitory factor (LIF) favours the survival and growth of axons in vitro. The efficacy of this factor in the in vivo model has been the aim of this study. Following nerve transection and immediate entubulation repair in the rat sciatic nerve, this study demonstrated that (1) LIF promotes the growth of a population of axons of greater cross-sectional area after 6 and 12 weeks in comparison to either saline (negative control) or basic fibroblast growth factor (bFGF) (positive control), (2) LIF improves the nerve conduction velocity of regenerating axons, (3) LIF has a positive effect on skeletal muscle mass following nerve repair, (4) the benefits of LIF on skeletal muscle appear to be somewhat independent of reinnervation as similar observations are made where there is no growth of a tissue bridge within the tube, and (5) the effects of LIF seem to be potentiated by the addition of fibronectin.
Supervision registers for mentally ill people.
Explore the source record for details and available documents.
Superlattice formation in binary mixtures of hard-sphere colloids.
Explore the source record for details and available documents.
Complex sensor systems: odour detection by the sense of smell and by electronic noses.
Explore the source record for details and available documents.
Structure of crystals of hard colloidal spheres.
Explore the source record for details and available documents.
Inflammatory abdominal aortic aneurysm: a cause of urinary obstruction and acute renal failure.
Abdominal aortic aneurysms are rare causes of ureteric obstruction. We report three cases of inflammatory abdominal aortic aneurysm producing hydronephrosis. In two patients acute renal failure preceded this presentation. The diagnosis can be established by computed tomography when mural thrombus, wall calcification, and an enhancing periaortic soft-tissue mantle are present. It is important to recognize this disease preoperatively.
Colorectal polyps: a correlation of radiological and pathological findings.
Ninety colorectal polyps seen on double contrast barium enema were reviewed and note was made of surface and base characteristics, size, site and the presence of associated disease. Results were then correlated with the histology. The radiological characteristics of each histological type of polyp encountered are described. Because of the variation in radiological appearance of each histological type and similarities in appearance between these types, we conclude that radiology cannot accurately predict the histology of a colorectal polyp.
Magnetic resonance imaging (MRI) of the orbit.
Explore the source record for details and available documents.
Kinetics of enzymes requiring long-chain acyl-CoA esters as substrates: effects of substrate binding to albumin.
Explore the source record for details and available documents.