Proliferation-related expression of p19/nm23 nucleoside diphosphate kinase.

High level expression of the nm23-H1 gene, which encodes for a nucleoside diphosphate kinase, has been found to correlate with diminished metastasis in some tumors but not in others. We have previously identified the protein product of the nm23-H1 gene in two-dimensional electrophoretic gels and have designated it p19/nm23. In neuroblastoma, higher levels of p19/nm23, which are associated with amplification of the N-myc oncogene, large tumor mass, and metastasis, were observed in advanced stage tumors compared with limited stage disease. Because of the variable expression of nm23-H1 in different tumors, we have investigated the relationship between amounts of the protein and cell proliferation. The levels of p19/nm23 were compared between resting and mitotically stimulated normal human PBLs and in leukemia cells. The amount of p19/nm23 increased in normal lymphocytes in response to mitotic stimulation and paralleled the increase in DNA synthesis. In leukemia cells obtained from patients with different subtypes of acute leukemia, p19/nm23 levels were also increased relative to resting normal lymphocytes. Treatment of mitotically stimulated lymphocytes with cyclosporin, which inhibits proliferation, blocked the increase in p19/nm23; treatment of the leukemia cell line HL-60 with dimethylsulfoxide, which induces terminal differentiation, resulted in diminished levels of p19/nm23. Our data therefore provide evidence that nm23-H1 expression is related to cell proliferative activity.     

Secondary cataract; correlations concerning lens surgery and pseudophakia type. Therapeutic aspects

The study presents the correlations concerning the advent of the secondary cataract depending on the surgical technique and pseudofak type (PMMA, acrylic, siliconic), as well the safety and efficacy of the YAG: Nd capsulotomy. A 3 years clinical retrospective trial was done on 320 eyes operated for senile cataract. The incidence of the secondary cataract was 11.4%, usually after 12 months, (the lower in phacoemulsification using acrylic IOL). Nd: YAG capsulotomy being done in cases with visual acuity lower than 0.6.     

In situ magnetic identification of giant,needle-shaped magnetofossils in Paleocene–Eocene Thermal Maximum sediments

Near-shore marine sediments deposited during the Paleocene–Eocene Thermal Maximum at Wilson Lake, NJ, contain abundant conventional and giant magnetofossils. We find that giant, needle-shaped magnetofossils from Wilson Lake produce distinct magnetic signatures in low-noise, high-resolution first-order reversal curve (FORC) measurements. These magnetic measurements on bulk sediment samples identify the presence of giant, needle-shaped magnetofossils. Our results are supported by micromagnetic simulations of giant needle morphologies measured from transmission electron micrographs of magnetic extracts from Wilson Lake sediments. These simulations underscore the single-domain characteristics and the large magnetic coercivity associated with the extreme crystal elongation of giant needles. Giant magnetofossils have so far only been identified in sediments deposited during global hyperthermal events and therefore may serve as magnetic biomarkers of environmental disturbances. Our results show that FORC measurements are a nondestructive method for identifying giant magnetofossil assemblages in bulk sediments, which will help test their ecology and significance with respect to environmental change.

The Paleocene–Eocene Thermal Maximum (PETM; ∼56 Ma) is a geologically rapid global warming event with many characteristics that make it an analog for the Anthropocene (1, 2). These characteristics include rapid warming of the sea surface and atmosphere, increased seasonality of precipitation and temperature, and biological extinctions (1). The PETM is identified globally by a −3‰ carbon isotope excursion (CIE) in bulk marine carbonate and is characterized by three stratigraphic intervals: 1) a preonset excursion, 2) the main CIE, and 3) a recovery toward baseline δ¹³C levels (1). The main CIE interval is further subdivided into the CIE onset and CIE core, which correspond to the first ∼6 to 10 kyr and 100 to 200 kyr of the PETM (1, 3, 4). The Wilson Lake A (WL-A) core from Wilson Lake, NJ, contains a continental shelf section of the PETM within the Marlboro Clay and, within the Marlboro Clay, an expanded and nearly complete record of the CIE onset and CIE core (1, 5). Several near-shore and offshore cores complement the WL-A record and enable a broader understanding of how Paleogene coastal ecosystems responded to the rapid onset of global hyperthermal conditions (5–8). The New Jersey continental shelf experienced an overall rapid influx of clay, mineralization of iron oxides, dinoflagellate blooms, and benthic foraminifera species turnover coincident with the CIE onset (5, 9, 10).Abundant conventional and giant magnetofossils, the fossil remains of magnetotactic bacteria and other iron-biomineralizing microorganisms, were identified in several New Jersey cores. These magnetofossils are interpreted to be the predominant source of the PETM magnetic enhancement of these cores (7, 11–14), although alternative sources have been suggested (15–18). Giant magnetofossils have so far only been identified in sediments from the PETM and the Middle Eocene Climatic Optimum, leading to the interpretation that they are unique to hyperthermal events (6, 7, 11–14). For example, Chang et al. (6) suggest that giant magnetofossils are linked to oceanic deoxygenation during the PETM.Previous studies, which used micromagnetic simulations, electron holography, or both, suggest that giant magnetofossils have distinct magnetic properties (6, 11, 14, 18, 19). These interpretations are limited, however, by assumptions regarding crystal arrangement, spacing, and magnetic domain structure, and they lack independent confirmation of defining characteristics. Additionally, some of these methods have been applied to only a few giant magnetofossil morphologies.Here we show independent, physical evidence of the magnetic signature of giant magnetofossils in situ (i.e., not in extracts) using low-noise, high-resolution first-order reversal curves (FORCs). FORC routines measure the response of all magnetic particles, including giant magnetofossils, within a bulk sediment sample. We also present micromagnetic simulations of giant needle-shaped crystals whose morphologies were characterized with transmission electron microscopy (TEM) of magnetic extracts. Our results show that giant, needle-shaped magnetofossils produce a high-coercivity component distinct from conventional magnetofossils that is identified using a specific FORC measurement protocol. We argue that these are definitive magnetic signatures of giant magnetofossils, which further supports the interpretation that the magnetic enhancement of the WL-A core has a biogenic origin. The link between giant magnetofossils, hyperthermal events, and oceanic deoxygenation makes the magnetic signature of giant needles a powerful tool for identifying giant magnetofossil assemblages and, by extension, testing their ecological significance in the context of global change events in the geologic record.     

Effects of protein kinase A inhibitor and activator on rewarding effects of SKF-82958 microinjected into nucleus accumbens shell of ad libitum fed and food-restricted rats

Rationale

Previous studies indicate that the rewarding effect of D-1 dopamine receptor stimulation in nucleus accumbens (NAc) shell is greater in food-restricted (FR) than in ad libitum fed (AL) rats. The D-1 receptor is positively coupled to adenylyl cyclase and activates protein kinase A (PKA).

Objectives

The purpose of this study was to determine whether PKA is involved in the rewarding effect of D-1 receptor stimulation and, if so, whether it is involved in the enhanced response of FR rats.

Materials and methods

Rats were stereotaxically implanted with microinjection cannulae in NAc shell and a stimulating electrode in lateral hypothalamus. The rewarding effects of SKF-82958 (1.5 or 3.0?μg, bilaterally) in the presence and absence of PKA inhibitor, Rp-cAMPS (8.9?μg), and PKA activator, Sp-cAMPS (8.9?μg), were assessed using the curve-shift method of intracranial self-stimulation (ICSS). Basal NAc levels of DARPP-32 phosphorylated on Thr34 and Thr75 were measured.

Results

Rp-cAMPS increased the rewarding effect of SKF-82958 in AL but not FR rats, doubling the ICSS threshold-lowering effect of the 3.0-μg dose. Sp-cAMPS decreased the rewarding effect of SKF-82958 in FR but not AL rats. Levels of phospho-DARPP-32 (Thr75), which inhibits PKA, were higher in FR than AL rats.

Conclusions

Results indicate that inhibition of PKA enhances the unconditioned rewarding effect of D-1 receptor stimulation and that decreased PKA may be involved in the effect of FR on drug reward. Evidence for involvement of D-2 receptor-expressing neurons in the enhancing effect of PKA inhibition is discussed.     

Aggregation of the neuroblastoma-associated mutant (S120G) of the human nucleoside diphosphate kinase-A/NM23-H1 into amyloid fibrils

The human nucleoside diphosphate (NDP) kinase A, product of the NME1 gene also named NM23-H1, is known as a metastasis suppressor protein. A naturally occurring variant, S120G, identified in neuroblastomas, possesses native three-dimensional structure and enzymatic activity but displays reduced conformational stability and a folding defect with the accumulation of a "molten globule" folding intermediate during refolding in vitro. As such intermediate has been postulated to be involved in amyloid formation, NDP kinase A may serve as a model protein for studying the relationship between folding intermediates and amyloid fibrils. The NDP kinase A S120G was heated in phosphate buffer (pH?7.0). The protein precipitated as amyloid fibrils, as demonstrated by electron microscopy, Congo red, and thioflavin T binding and FTIR spectroscopy. The NDP kinase A S120G, at neutral pH and at moderate temperature experiences a transition towards amyloid fibrils. The aggregation process was faster if seeded by preformed fibrils. The fibrils presented a large proteinase K-resistant core not including residue Gly 120, as shown by mass spectrometry. This suggests that the aggregation process is triggered by the reduced stability of the S120G variant and not by a specific increase in the kinase domain intrinsic aggregation propensity at the place of mutation. This constitutes one of the few reports on a protein involved in cancer biology able to aggregate into amyloid structures under mild conditions.