Hydrostatic pressure to 400 atm does not induce changes in the cytosolic concentration of Ca2+ in mouse fibroblasts: measurements using fura-2 fluorescence.

Hydrostatic pressure has a pronounced effect on the morphology and cytoskeletal organization of mammalian tissue cells. At pressures of about 300 atm (30 MPa), cells "round up"-they withdraw their lamellar extensions and greatly rearrange actin, tubulin, and several other cytoskeletal proteins. It has been proposed that these changes are caused by a pressure-induced elevation of cytosolic Ca2+ concentrations.

Anterior cingulate dysfunction in presenile dementia due to progressive supranuclear palsy.

We report neuropsychological and neuroimaging investigations performed in a patient suffering from presenile onset degenerative dementia and subsequent mild extrapyramidal and pyramidal signs. Early neuropsychological testing revealed frontal lobe dysfunction. Neuroanatomical pictures were not contributive.

Postencephalitic stereotyped involuntary movements responsive to L-Dopa.

In 1954, at the age of 5 years, our patient had an encephalitic syndrome associated with a prolonged lethargic state. After this episode, he developed a severe parkinsonian syndrome that, after a few years, was associated with axial dystonia and stereotyped abnormal movements of the upper limbs. This complex and progressive extrapyramidal syndrome had many similarities to the encephalitis lethargica as described by von Economo.

Frontal lobe dementia presenting as personality disorder.

The early differential diagnosis of frontal lobe dementia is particularly difficult because changes of personality or behaviour overwhelm intellectual and cognitive impairments. We report the case of a patient presenting with paranoid personality disorder who refused to collaborate in neuropsychological testing. Initial functional imaging showed frontal hypometabolism that served as an early marker of frontal lobe dysfunction.

Combined study of cerebral glucose metabolism and [11C]methionine accumulation in probable Alzheimer's disease using positron emission tomography.

There is a characteristic decrease in glucose metabolism in associative frontal and temporo-parietal cortices of patients suffering from Alzheimer's disease (AD). The decrease in metabolism might result from local neuronal loss or from a decrease of synaptic activity. We measured in vivo [11C]methionine accumulation into proteins with positron emission tomography (PET) to assess cortical tissue loss in AD.

[Parkinsonian syndrome and post-encephalitic stereotyped involuntary movements responsive to L-dopa].

In 1954, when he was five years old, a patient suffered from encephalitis with a prolonged lethargic state. Following this episode, he presented a severe parkinsonian syndrome which was associated, after a few years, with an axial dystonia and stereotyped involuntary movements of the upper limbs. These abnormal movements were particular by their coordinated appearance, their rhythmicity and their relative slowness.

Cytoskeleton: a catastrophic kinesin.

The 'plus' ends of microtubules exhibit dynamic instability, switching stochastically from growth to shortening phases. The first endogenous regulator of such 'catastrophes' has been identified, and is a kinesin-related microtubule motor protein.

Digital photography for the light microscope: results with a gated, video-rate CCD camera and NIH-image software.

In this report, we describe a relatively inexpensive method for acquiring, storing and processing light microscope images that combines the advantages of video technology with the powerful medium now termed digital photography. Digital photography refers to the recording of images as digital files that are stored, manipulated and displayed using a computer. This report details the use of a gated video-rate charge-coupled device (CCD) camera and a frame grabber board for capturing 256 gray-level digital images from the light microscope.

Force generation by microtubule assembly/disassembly in mitosis and related movements.

In this article, we review the dynamic nature of the filaments (microtubules) that make up the labile fibers of the mitotic spindle and asters, we discuss the roles that assembly and disassembly of microtubules play in mitosis, and we consider how such assembling and disassembling polymer filaments can generate forces that are utilized by the living cell in mitosis and related movements.

Chromosomes take an active role in spindle assembly.

The assembly of a bipolar spindle is essential for the accurate segregation of replicated chromosomes during cell division. Do chromosomes rely solely on other cellular components to regulate the assembly of the bipolar spindle or are they masters of their own fate? In the Zhang and Nicklas(1) study reviewed here, micromanipulation techniques and video microscopy were used to demonstrate the different roles that chromosome arms, kinetochores and centrosomes play in bipolar spindle assembly.

Serotonin 5HT2 receptor imaging in the human brain using positron emission tomography and a new radioligand, [18F]altanserin: results in young normal controls.

Changes in serotonin-2 receptors have been demonstrated in brain autopsy material from patients with various neurodegenerative and affective disorders. It would be desirable to locate a ligand for the study of these receptors in vivo with positron emission tomography (PET). Altanserin is a 4-benzoylpiperidine derivative with a high affinity and selectivity for S2 receptors in vitro.

Membrane/microtubule tip attachment complexes (TACs) allow the assembly dynamics of plus ends to push and pull membranes into tubulovesicular networks in interphase Xenopus egg extracts.

We discovered by using high resolution video microscopy, that membranes become attached selectively to the growing plus ends of microtubules by membrane/microtubule tip attachment complexes (TACs) in interphase-arrested, undiluted, Xenopus egg extracts. Persistent plus end growth of stationary microtubules pushed the membranes into thin tubules and dragged them through the cytoplasm at the approximately 20 microns/min velocity typical of free plus ends. Membrane tubules also remained attached to plus ends when they switched to the shortening phase of dynamic instability at velocities typical of free ends, 50-60 microns/min.

Spindle dynamics and cell cycle regulation of dynein in the budding yeast, Saccharomyces cerevisiae.

We have used time-lapse digital- and video-enhanced differential interference contrast (DE-DIC, VE-DIC) microscopy to study the role of dynein in spindle and nuclear dynamics in the yeast Saccharomyces cerevisiae. The real-time analysis reveals six stages in the spindle cycle. Anaphase B onset appears marked by a rapid phase of spindle elongation, simultaneous with nuclear migration into the daughter cell.

Kinetochore motility after severing between sister centromeres using laser microsurgery: evidence that kinetochore directional instability and position is regulated by tension.

During mitosis in vertebrate somatic cells, the single attached kinetochore on a mono-oriented chromosome exhibits directional instability: abruptly and independently switching between constant velocity poleward and away from the pole motility states. When the non-attached sister becomes attached to the spindle (chromosome bi-orientation), the motility of the sister kinetochores becomes highly coordinated, one moving poleward while the other moves away from the pole, allowing chromosomes to congress to the spindle equator. In our kinetochore-tensiometer model, we hypothesized that this coordinated behavior is regulated by tension across the centromere produced by kinetochore movement relative to the sister kinetochore and bulk of the chromosome arms.

VE-DIC light microscopy and the discovery of kinesin.

Major advances in science are often tightly coupled with the development of new technology. The discovery of kinesin is an excellent example of this principle. The new technology was video-enhanced differential interference contrast light microscopy, which provided the enormous gain in image contrast needed to detect and measure kinesin-based motility in living cells, cell extracts and in vitro motility assays.

Directed movement of chromosome arms and fragments in mitotic newt lung cells using optical scissors and optical tweezers.

A pulsed-laser microbeam at 532 nm wavelength (optical scissors) and a laser-induced optical trap at 1064 nm wavelength (optical tweezers) have been successively combined to dissect and manipulate chromosomes in live newt lung epithelial cells. These preliminary experimental results demonstrated that chromosome fragments dissected by laser microbeam surgery, regardless of their size, could be easily pulled or rotated by optical forces when positioned at the periphery of the mitotic spindle. In addition, chromosome arms which were not subjected to laser microsurgery also could be moved with the optical tweezers at the spindle periphery.

Yeast Kar3 is a minus-end microtubule motor protein that destabilizes microtubules preferentially at the minus ends.

Mutants of the yeast Kar3 protein are defective in nuclear fusion, or karyogamy, during mating and show slow mitotic growth, indicating a requirement for the protein both during mating and in mitosis. DNA sequence analysis predicts that Kar3 is a microtubule motor protein related to kinesin, but with the motor domain at the C-terminus of the protein rather than the N-terminus as in kinesin heavy chain. We have expressed Kar3 as a fusion protein with glutathione S-transferase (GST) and determined the in vitro motility properties of the bacterially expressed protein.

Mutants of the Drosophila ncd microtubule motor protein cause centrosomal and spindle pole defects in mitosis.

Nonclaret disjunctional (ncd) is a kinesin-related microtubule motor protein required for meiotic and early mitotic chromosome distribution in Drosophila. ncd translocates on microtubules with the opposite polarity to kinesin, toward microtubule minus ends, and is associated with spindles in chromosome/spindle preparations. Here we report a new mutant of ncd caused by partial deletion of the predicted coiled-coil central stalk.

Differential diagnosis of Alzheimer's disease with PET.

Unlabelled: PET studies have demonstrated bilateral temporo-parietal hypoperfusion and hypometabolism in probable and definite Alzheimer's disease (AD), a pattern that may help differentiate AD from other dementias.

Methods: To evaluate the diagnostic power of cerebral metabolic distribution patterns for "cortical" degenerative dementias, PET scans obtained from 129 patients referred for differential diagnosis of dementia were analyzed visually.

Results: Sixty-five patients had a final clinical diagnosis of probable AD.

Motile kinetochores and polar ejection forces dictate chromosome position on the vertebrate mitotic spindle.

We argue that hypotheses for how chromosomes achieve a metaphase alignment, that are based solely on a tug-of-war between poleward pulling forces produced along the length of opposing kinetochore fibers, are no longer tenable for vertebrates. Instead, kinetochores move themselves and their attached chromosomes, poleward and away from the pole, on the ends of relatively stationary but shortening/elongating kinetochore fiber microtubules. Kinetochores are also "smart" in that they switch between persistent constant-velocity phases of poleward and away from the pole motion, both autonomously and in response to information within the spindle.