SUMMARYThe quantitative analysis of cell m otility in culture has several im portant functions. F irst, it gives a concise and accurate description of the m otile process and can detect subtle differences in m otility due to different genetic m akeup or experim ental conditions. Second, its objectivity m eans that results can be com m unicated precisely and used unam biguously to test hypotheses about m otility. T h ird , it may be used to derive a m athem atical model w ith the same statistical properties as the motile process and thus elucidate the m echanism of motility.In this paper, we introduce a general procedure for analysing cell m otility in a wide variety of circum stances. We describe a pilot project for the analysis of sim ple geom etrical data obtained from random ly m oving fibroblasts. Finally, as an example, we show how an analysis of the translocation of the fibroblasts can lead to insights into the m echanism of m otility th a t are arguably not obtainable by anv oth er approach. WHY ANALYSE CELL MOTILITY?An outstanding problem in the study of cell motility is how the locomotorv m achinery is controlled and coordinated. What are the overall dynamics of it? T he analysis of the m olecular com ponents of the locomotory m achinery, and their interactions, has made great progress over the last 15 vears or so, particularly in those interactions where there is a clear homology with muscle. T h e dynam ics of assembly and disassem bly of these com ponents are now also beginning to emerge and we are perhaps not far from understanding many of the basic molecular interactions of cell m otility. How are we going to relate these properties at the m olecular level to the behavioural properties of the whole cell?At the level of cell behaviour, it is often convenient to discuss the m echanism of cellular retraction, traction, protrusion or persistence in direction as if they were isolated processes and it is tem pting to associate each with a separate molecular m echanism . F or example, the first m ight involve actin-m yosin interactions, and the second m ight require an additional transm em brane molecular linkage system ; the third m ight require actin assembly and the fourth tubulin assembly and interactions with other proteins. However, m ost investigators agree that these processes have a degree of interdependence, even if only that they utilize com m on m olecular pools and are jointlv affected by such global factors as changes in ion concentrations. Nevertheless, there is still a danger in treating the motile system as if it were a collection of relatively independent subsystem s susceptible to individual analysis. T h e possibility exists, for example, that the processes are interdependent at a deeper level. T raction, retraction, protrusion and persistence in direction may be merely
A new form of chamber for studying chemotaxis, similar in principle to the Zigmond chamber, allows the behaviour of the cells in a linear concentration gradient to be observed directly. The chamber was developed mainly for studying chemotaxis in fibroblasts using interferometric microscopy and the main design criteria were that it should have better optical characteristics, a higher dimensional precision and better long-term stability than the Zigmond chamber. It is made entirely from glass by grinding a blind circular well centrally in the counting platform of a Helber bacteria counting chamber. This procedure leaves an annular ‘bridge’, approximately 1 mm wide, between the new inner circular well and the original outer annular well. This bridge fulfils the same function as the linear bridge of the Zigmond chamber but the precise construction of the counting chamber ensures that a gap of 20 microns between bridge and coverslip can be accurately and repeatedly achieved when the chamber is assembled. It is envisaged that the improved optical clarity, dimensional accuracy and long-term stability of the new chamber will be advantageous in other applications, particularly in studies requiring critical microscopy or a precise knowledge of the gradient and in studies of cells, such as fibroblasts, that move much more slowly than neutrophils.
Communicated by Mark H. PaalmanExpert curation and complete collection of mutations in genes that affect human health is essential for proper genetic healthcare and research. Expert curation is given by the curators of gene-specific mutation databases or locusspecific databases (LSDBs). While there are over 700 such databases, they vary in their content, completeness, time available for curation, and the expertise of the curator. Curation and LSDBs have been discussed, written about, and protocols have been provided for over 10 years, but there have been no formal recommendations for the ideal form of these entities. This work initiates a discussion on this topic to assist future efforts in human genetics. Further discussion is welcome. Hum Mutat 29(1), 2-5, 2008.
Experimental and clinical data suggest that GABA-ergic drugs such as valproate may have a potential role in the treatment of schizophrenia. The authors designed a 21-day prospective, double-blind, randomized, placebo-controlled pilot study of divalproex sodium as add-on treatment to haloperidol in 12 hospitalized patients with acute exacerbations of chronic schizophrenia. All patients received haloperidol 10 mg/day for 3 days and 15 mg/day for the remaining 18 days. In addition, five patients were randomly assigned to receive divalproex augmentation and seven to receive placebo. The divalproex dose was adjusted to a target serum concentration of 75 microg/mL for 2 weeks; placebo replaced divalproex during the third and last weeks to determine any carryover effect. Psychiatric rating scales were administered at baseline and on days 7, 14, and 21. Although the placebo group improved with haloperidol treatment, the divalproex group demonstrated greater improvement. On day 21, the divalproex group had greater improvement from baseline on the Clinical Global Impression Scale (p < or = 0.04), Brief Psychiatric Rating Scale (p < or = 0.13), and Schedule for Assessment of Negative Symptoms scores (p < or = 0.007). After divalproex withdrawal on day 15, a carryover effect was observed during week 3. The authors concluded that the addition of divalproex sodium to standard antipsychotic drugs may prove effective in relieving the symptoms of acute schizophrenia. Future studies may benefit from the design of this pilot study. However, it is premature to apply this augmentation strategy in the clinical setting just yet because of the small sample size and the likely heterogeneity of the disorder.
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