Genetic deletion of faim reveals its role in modulating c-FLIP expression during CD95-mediated apoptosis of lymphocytes and hepatocytes

Fas-apoptosis inhibitory molecule (FAIM) is inducibly expressed in B lymphocytes and had been shown to antagonize Fas-mediated killing of B-cell lines in vitro. However, its mechanism and role in vivo are unknown. We have generated faim(-/-) mice and found these mutants to be viable. In contrast to fas(-/-) mice, faim(-/-) mice have normal B- and T-cell populations. However, faim(-/-) B cells and thymocytes show increased sensitivity to Fas-triggered apoptosis in vitro, and faim(-/-) mice suffer greater mortality and exhibit exacerbated liver damage in response to Fas (CD95) engagement in vivo. The lack of FAIM results in greater activation of caspase-8 and -3 in Fas-stimulated thymocytes. Detailed biochemical analyses further reveal the decreased expression of c-FLIP(L) and c-FLIP(R) in faim(-/-) thymocytes and increased association of caspase-8 with Fas in Fas-activated mutant cells. Decreased levels of c-FLIP(L) and c-FLIP(R) are also evident in faim(-/-) liver. Thus, FAIM plays a novel role in modulating Fas-mediated apoptosis and acts through influencing the expression of c-FLIP and regulating the physical binding of caspase-8 to Fas.

Effects of a natural extract of chestnut wood on digestibility, performance traits, and nitrogen balance of broiler chicks

Currently, feed ingredients containing tannin are attracting more interest as substitutes for antibiotic growth promoters in animal and poultry feeding. This study investigated the influence of a natural extract of chestnut wood (Silvafeed ENC) on broiler digestibility (experiment 1) and on the growth performance, carcass quality, and nitrogen balance of broilers (experiment 2). Results showed that the inclusion of ENC did not influence the apparent digestibility of organic matter, CP, and ether extract. Chick growth performance showed a quadratic or cubic response with increasing levels of ENC. When chicks were fed ENC from 14 to 56 d of age, the ENC had a positive effect on average daily gain in the first 2 wk of addition, whereas this effect was not evident in the last 2 wk compared with the control group. Similar trends were also shown for daily feed intake. Overall, the chicks fed 0.20% ENC had significantly better growth performance than the control group. Carcass analysis showed no gross lesions in organs and no significant differences in thigh and breast composition among groups. Noteworthy is the fact that the ENC-treated groups had less total litter nitrogen; in particular, chicks fed 0.15 and 0.20% ENC showed a significant difference in total litter nitrogen compared with the control group. No significant difference in nitrogen balance was observed. Addition of 0.20% ENC seemed to have a positive influence on chick feeding.

Activation of granulocytes by direct interaction with dendritic cells

Granulocytes from human peripheral blood were co-cultured with conventional dendritic cells (cDC) or plasmacytoid DCs (pDC) to examine the effects of DCs on the activation or function of granulocytes. After co-culture of granulocytes with DCs, expression of the activation markers of granulocytes (CD63 and CD64) was up-regulated, and increased expression of CD50, the activation marker and ligand for CD209 (DC-SIGN) was also observed. The interaction of granulocytes with DCs was visualized as the cluster where DCs, especially cDCs, were surrounded by granulocytes to form a 'rosette'. After co-culture of granulocytes with cDCs, the secretion of elastase from granulocytes was enhanced significantly when examined cytohistochemically and by enzyme-linked immunosorbent assay. An increase in myeloperoxidase (another activation index of granulocytes) was also observed after co-culture with DCs. These findings suggest the functional and phenotypical activation of granulocytes by interaction with DCs. Furthermore, we examined the involvement of adhesion molecules in the granulocyte-DC interaction, and found that CD209 participates to some extent in this interaction.

Aptamer-based isolation and subsequent imaging of mesenchymal stem cells in ischemic myocard by magnetic resonance imaging

PURPOSE

Mesenchymal stem cells (MSC) seem to be a promising cell source for cellular cardiomyoplasty. We recently developed a new aptamer-based specific selection of MSC to provide "ready to transplant" cells directly after isolation. We evaluated MRI tracking of newly isolated and freshly transplanted MSC in the heart using one short ex vivo selection step combining specific aptamer-based isolation and labeling of the cells.

MATERIALS AND METHODS

Bone marrow (BM) was collected from healthy pigs. The animals were euthanized and the heart was placed in a perfusion model. During cold ischemia, immunomagnetic isolation of MSC from the BM by MSC-specific aptamers labeled with Dynabeads was performed within 2 h. For histological identification the cells were additionally stained with PKH26. Approx. 3 x 10(6) of the freshly aptamer-isolated cells were injected into the ramus interventricularis anterior (RIVA) and 5 x 10(5) cells were injected directly into myocardial tissue after damaging the respective area by freezing (cryo-scar). 3 x 10(6) of the aptamer-isolated cells were kept for further characterization (FACS and differentiation assays). 20 h after cell transplantation, MRI of the heart using a clinical 3.0 Tesla whole body scanner (Magnetom Trio, Siemens, Germany) was performed followed by histological examinations.

RESULTS

The average yield of sorted cells from 120 ml BM was 7 x 10(6) cells. The cells were cultured and showed MSC-like properties. MRI showed reproducible artifacts within the RIVA-perfusion area and the cryo-scar with surprisingly excellent quality. The histological examination of the biopsies showed PKH26-positive cells within the areas which were positive in the MRI in contrast to the control biopsies.

CONCLUSION

Immunomagnetic separation of MSC by specific aptamers linked to magnetic particles is feasible, effective and combines a specific separation and labeling technique to a "one stop shop" strategy.

Molecular and phenotypic characterization of infectious bursal disease virus isolates

Two infectious bursal disease viruses (IBDVs 1174 and V1) were isolated from IBDV-vaccinated broiler flocks in California and Georgia. These flocks had a history of subclinical immunosuppression. These isolates are commonly used in IBDV progeny challenge studies at Auburn, AL, as well as vaccine manufacturer's vaccine efficacy studies, because they come from populated poultry-producing states, and are requested by poultry veterinarians from those states. Nested polymerase chain reaction (PCR) generated viral genome products for sequencing. A 491-bp segment from the VP2 gene, covering the hypervariable region, from each isolate was analyzed and compared with previously sequenced isolates. Sequence analysis showed that they were more closely related to the Delaware (Del) E antigenic variant than they are to the Animal Health Plant Inspection Service (APHIS) standard, both at the nucleotide level (96%, 97%) and at the amino acid level (94%, 97%). Both isolates had the glutamine to lysine shift in amino acid 249 which has been reported to be critical in binding the virus neutralizing Mab B69. Phenotypic studies showed that both isolates produced rapid atrophy of the bursae and weight loss, without the edematous bursal phase, in 2-wk-old commercial broilers having antibody against IBDV. A progeny challenge study showed both isolates produced more atrophy of the bursae (less percentage of protection) than the Del E isolate. Molecular and phenotypic data of these important IBDV isolates help in the improved detection and control of this continually changing and important viral pathogen of chickens.

Upregulation of frizzled 9 in astrocytomas

Wnt/frizzled (FZD) cascades play important roles in controlling cell fate, proliferation, migration, tissue architecture and organogenesis during embryonic development and in adult organisms. The potential involvement of this pathway in tumorigenesis has been established in several types of cancers. Frizzled 9 (FZD9) is expressed in brain and its aberrant expression in gastric cancer was observed. However, its association with astrocytomas remains unknown therefore we studied FZD9 expression in astrocytomas of different malignancy. In the present study, FZD9 expression in 25 astrocytomas was investigated using immunohistochemistry with specific antibodies. Further FZD9 expression in native human brain tissue and glioblastoma cell line were analysed using real-time reverse transcription polymerase chain reaction (RT-PCR). In human astrocytomas, FZD9 immunoreactivity (IR) was observed in both microvessels and neoplastic cells. The percentage of FZD9+ microvessels in relation to FZD9+ vessels was significantly higher in malignant astrocytomas than in low-grade astrocytomas and positively correlated with the astrocytoma World Health Organization (WHO) grading (r = 1, P = 0.04). Furthermore, the FZD9 IR scores positively correlated with astrocytoma WHO grading (r = 1, P = 0.04) and proliferating activity (r = 0.77, P < 0.001). Real-time RT-PCR data showed that FZD9 expression in human glioblastoma was significant higher than in normal brain (P < 0.05) but FZD9 expression was only slightly induced in cobalt chloride-treated human glioblastoma T98G cells compared with untreated cells (P > 0.05). FZD9 is upregulated in astrocytomas, suggesting that FZD9 could be important in the tumorigenesis of human astrocytomas.

Cholinergic modulation of response properties and orientation tuning of neurons in primary visual cortex of anaesthetized Marmoset monkeys

Cortical processing is strongly influenced by the actions of neuromodulators such as acetylcholine (ACh). Early studies in anaesthetized cats argued that acetylcholine can cause a sharpening of orientation tuning functions and an improvement of the signal-to-noise ratio (SNR) of neuronal responses in primary visual cortex (V1). Recent in vitro studies have demonstrated that acetylcholine reduces the efficacy of feedback and intracortical connections via the activation of muscarinic receptors, and increases the efficacy of feed-forward connections via the activation of nicotinic receptors. If orientation tuning is mediated or enhanced by intracortical connections, high levels of acetylcholine should diminish orientation tuning. Here we investigate the effects of acetylcholine on orientation tuning and neuronal responsiveness in anaesthetized marmoset monkeys. We found that acetylcholine caused a broadening of the orientation tuning in the majority of cells, while tuning functions became sharper in only a minority of cells. Moreover, acetylcholine generally facilitated neuronal responses, but neither improved signal-to-noise ratio, nor reduced trial-to-trial firing rate variance systematically. Acetylcholine did however, reduce variability of spike occurrences within spike trains. We discuss these findings in the context of dynamic control of feed-forward and lateral/feedback connectivity by acetylcholine.

Primary visual cortex neurons that contribute to resolve the aperture problem

It is traditional to believe that neurons in primary visual cortex are sensitive only or principally to stimulation within a spatially restricted receptive field (classical receptive field). It follows from this that they should only be capable of encoding the direction of stimulus movement orthogonal to the local contour, since this is the only information available in their classical receptive field "aperture." This direction is not necessarily the same as the motion of the entire object, as the direction cue within an aperture is ambiguous to the global direction of motion, which can only be derived by integrating with unambiguous components of the object. Recent results, however, show that primary visual cortex neurons can integrate spatially and temporally distributed cues outside the classical receptive field, and so we reexamined whether primary visual cortex neurons suffer the "aperture problem." With the stimulation of an optimally oriented bar drifting across the classical receptive field in different global directions, here we show that a subpopulation of primary visual cortex neurons (25/81) recorded from anesthetized and paralyzed marmosets is capable of integrating informative unambiguous direction cues presented by the bar ends, well outside their classical receptive fields, to encode global motion direction. Although the stimuli within the classical receptive field were identical, their directional responses were significantly modulated according to the global direction of stimulus movement. Hence, some primary visual cortex neurons are not local motion energy filters, but may encode signals that contribute directly to global motion processing.

Effects of milk urea nitrogen and other factors on probability of conception of dairy cows

The objective of this study was to evaluate the relationships between milk urea nitrogen (MUN) and other factors and the probability of conception in dairy cows. Data were retrieved from the Lancaster Dairy Herd Improvement Association (DHIA). A total of 713 dairy herds and 10,271 dairy cows were included in the study. Logistic regression was used to determine the within-herd effects of MUN, milk production, lactation number, and breeding season on the probability of conception for each of 3 services. Within herds, MUN displayed a slight negative association with probability of conception at first service. For example, there was a 2- to 4-percentage unit decrease in conception rate at first service with a 10-mg/dL increase in MUN. In among-herd regression analysis, there was no effect of MUN on probability of conception. These results suggest that MUN may be related to conditions affecting reproduction of individual cows within a herd. Diet formulation usually would affect MUN equally among all cows at a similar stage of lactation in a herd. Because there was no effect of MUN among herds, diet formulation did not appear to affect conception rate.

Acetylcholine dynamically controls spatial integration in marmoset primary visual cortex

Recent in vitro studies have shown that acetylcholine (ACh) selectively reduces the efficacy of lateral cortical connections via a muscarinic mechanism, while boosting the efficacy of thalamocortical/feed-forward connections via a nicotinic mechanism. This suggests that high levels of ACh should reduce center-surround interactions of neurons in primary visual cortex, making cells more reliant on feed-forward information. In line with this hypothesis, we show that local iontophoretic application of ACh in primate primary visual cortex reduced the extent of spatial integration, assessed by recording a neurons' length tuning. When ACh was externally applied, neurons' preferred length shifted toward shorter bars, showing reduced impact of the extra-classical receptive field. We fitted a difference and a ratio of Gaussian model to these data to determine the underlying mechanisms of this dynamic change of spatial integration. These models assume overlapping summation and suppression areas with different widths and gains to be responsible for spatial integration and size tuning. ACh significantly reduced the extent of the summation area, but had no significant effect on the extent of the suppression area. In line with previous studies, we also show that applying ACh enhanced the response in the majority of cells, especially in the later (sustained) part of the response. These findings are similar to effects of attention on neuronal activity. The natural release of ACh is strongly linked with states of arousal and attention. Our results may therefore be relevant to the neurobiological mechanism of attention.

[Analysis of short tandem repeats with fluorescence labeling polymerase chain reaction to document engraftment following allogeneic bone marrow transplantation]

OBJECTIVE

In order to determine the status of engraftment following allogeneic bone marrow transplantation (allo-BMT) and predict the outcome, short tandem repeats (STR) were analysed by fluorescence labeling polymerase chain reaction (PCR).

METHOD

Fluorescence labeling PCR detecting STR 9 loci was established. DNA was extracted by monoclonal magnetic beads from recipients peripheral blood nucleated cells and labeled with four color fluorescences before and from 7 days to six months after allogeneic bone marrow transplantation.

RESULTS

1. STR and clinical feature of 12 patients after allogeneic bone marrow transplantation were analysed. In the ten patients with full donor chimeras, 8 received marrow grafts from HLA identical sibling donors, 1 from HLA identical unrelated donor and 1 from HLA haploidentical mother. All of the 10 patients had durable engraftment and survived disease-freely for 3-25 months of follow-up. 2. One patient received a HLA-AB loci mismatched graft and his STR showed mixed chimeras at day 30, and converted into full donor chimeras at day 60 after transplantation. 3. One patient received HLA haploidentical sibling donor stem cells failed to be engrafted and died 4 months later.

CONCLUSION

Analysis of multi-loci of STR after allo-BMT provided a real indication of engraftment. Mixed chimeras after transplantation suggested that donor lymphocytes or bone marrow cells be re-infused to enhance the conversion from mixed chimeras to full donor chimeras. For the documentation of engraftment, analysis of STR was better than any other available methods.

[In vitro study of the killing activities on H-2(d) murine normal and tumor cells by Ly49A gene transfected lymphocytes]

OBJECTIVE

To observe the killing activities of Ly49A gene transfected lymphocytes of C57BL/6 mice to normal and tumor cells of BALB/c mice.

METHODS

pLXSN-Ly49A retrovirus vector was constructed and packaged with PA317 cell line. The lymphocytes of C57BL/6 mice were transfected by culture with virus producing PA317 cells. The Ly49A expression rate on the transfected lymphocytes was detected by flow cytometry and the killing activities of the transfected lymphocytes to normal and tumor cells of BALB/c mice were assayed by MTT method.

RESULTS

The Ly49A expression rates of C57BL/6 mice lymphocytes transfected with pLXSN-Ly49A for 24 hours, of those transfected with pLXSN and nontransfected control were (46.67 +/- 0.35)%, (18.73 +/- 0.85)%, and (19.60 +/- 0.27)%, respectively. The killing activity of the transfected lymphocytes to 4T(1) tumor cells remained almost the same as that of the control (P > 0.05), but to normal fibroblasts decreased sharply (inhibiting rate 22% - 25%).

CONCLUSION

The Ly49A transfected C57BL/6 mice lymphocytes could kill BALB/c mice tumor cells as effectively as the control did, but the activity decreased sharply to normal BALB/c mice cells, which would be instructive for resolving graft versus host disease after allogeneic bone marrow transplantation.

Hypoxia induces the expression of the pro-apoptotic gene BNIP3

It has been shown that oxygen deprivation results in apoptotic cell death, and that hypoxia inducible factor 1 (HIF1) and the tumor suppressor p53 play key roles in this process. However, the molecular mechanism through which hypoxia and HIF1 induce apoptosis is not clear. Here we show that the expression of pro-apoptotic gene BNIP3 is dramatically induced by hypoxia in various cell types, including primary rat neonatal cardiomyocytes. Overexpression of HIF1alpha, but not p53, induces the expression of BNIP3. Overexpression of BNIP3 leads to a rather unusual type of apoptosis, as no cytochrome c leakage from mitochondria was detected and inhibitors of caspases were unable to prevent cell death. Taken together, these data suggest that HIF1-dependent induction of BNIP3 may play a significant role during hypoxia-induced cell death.

[Human Fab antibodies derived from phage display library neutralize hepatitis A virus in vitro]

OBJECTIVE

Development of recombinant human monoclonal antibody to hepatitis A virus as a emergent measure for prevention of hepatitis A virus infection.

METHODS

Human neutralizing monoclonal antibody Fab fragments to HAV have been developed by using phage display technique. The heavy and light chains of human IgG Fab genes were amplified from a HAV patient in convalescent stage. The combinatorial phage antibody library was established by inserting both heavy and light chains of Fab genes into phage mid-vector pComb3 and followed by help phage infection after 4 rounds of panning with purified HAV as coated antigen.

RESULTS

The human Fab fragments to HAV were selected and expressed in bacteria.

CONCLUSIONS

The specific binding of Fab antibodies to HAV were demonstrated by their reaction with HAV antigen in ELISA. These results provide the basis for further development of a neutralizing recombinant human whole IgG molecule and hold promise for future use in the prophylaxis of HAV infection.

Inhibition of HIV-1 protease by a boron-modified polypeptide

Six boronated tetrapeptides with the carboxy moiety of phenylalanine replaced by dihydroxyboron were synthesized, and their activities against human immunodeficiency virus 1 (HIV-1) protease subsequently investigated. The sequences of these peptides were derived from HIV-1 protease substrates, which included the C-terminal part of the scissile bond (Phe-Pro) within the gag-pol polyprotein. Enzymatic studies showed that these compounds were competitive inhibitors of HIV-1 protease with K(i) values ranging from 5 to 18 microM when experiments were performed at high enzyme concentrations (above 5 x 10(-8) M); however, at low protease concentrations inhibition was due in part to an increase of the association constants of the protease subunits. Ac-Thr-Leu-Asn-PheB inhibited HIV-1 protease with a K(i) of 5 microM, whereas the non-boronated parental compound was inactive at concentrations up to 400 microM, which indicates the significance of boronation in enzyme inhibition. The boronated tetrapeptides were inhibitory to an HIV-1 protease variant that is resistant to several HIV-1 protease inhibitors. Finally, fluorescence analysis showed that the interactions between the boronated peptide Ac-Thr-Leu-Asn-PheB and HIV-1 protease resulted in a rapid decrease of fluorescence emission at 360 nm, which suggests the formation of a compound/enzyme complex. Boronated peptides may provide useful reagents for studying protease biochemistry and yield valuable information toward the development of protease dimerization inhibitors.

Pyridoxal kinase knockout of Dictyostelium complemented by the human homologue

The gene (pykA) encoding pyridoxal kinase which converts pyridoxal (vitamin B(6)) to pyridoxal phosphate was isolated from Dictyostelium discoideum using insertional mutagenesis. Cells of a pykA gene knockout grew poorly in axenic medium with low yield but growth was restored by the addition of pyridoxal phosphate. Sequencing indicated a gene, with one intron, encoding a predicted protein of 301 amino acids that was 42% identical in amino acid sequence to human pyridoxal kinase. After expression of the wild-type gene in Escherichia coli, the purified PykA protein product was shown to have pyridoxal kinase enzymatic activity with a K(m) of 8.7 microM for pyridoxal. Transformation of the Dictyostelium knockout mutant with the human pyridoxal kinase gene gave almost the same level of complementation as that seen using transformation with the wild-type Dictyostelium gene. Phylogenetic analysis indicated that the Dictyostelium amino acid sequence was closer to human pyridoxal kinase than to pyridoxal kinases of lower eukaryotes.

Mitochondria localization and dimerization are required for CIDE-B to induce apoptosis

Cell death-inducing DFF45-like effector (CIDE)-B is a member of the novel family of apoptosis-inducing factors that share homology with the N-terminal region of DFF, the DNA fragmentation factor. The molecular mechanism of CIDE-B-induced apoptosis is unclear. We have shown here that CIDE-B protein is localized in mitochondria and forms homodimers and heterodimers with other family members. Serial deletion analyses suggest that the mitochondria localization signal and dimerization interface are overlapped and localized to the 30 amino acid residues at the C-terminal region of CIDE-B. Mitochondria localization and dimerization are both required for CIDE-B-induced apoptosis. Our study has thus revealed a mechanism for CIDE-B-induced apoptosis by localization to mitochondria and the formation of a high affinity homo- or heterodimeric complex.

A temperature-sensitive adenylyl cyclase mutant of Dictyostelium

Dictyostelium development starts with the chemotactic aggregation of up to 10(6) amoebae in response to propagating cAMP waves. cAMP is produced by the aggregation stage adenylyl cyclase (ACA) and cells lacking ACA (aca null) cannot aggregate. Temperature-sensitive mutants of ACA were selected from a population of aca null cells transformed with a library of ACA genes, a major segment of which had been amplified by error-prone PCR. One mutant (tsaca2) that can complement the aggregation null phenotype of aca null cells at 22 degrees C but not at 28 degrees C was characterized in detail. The basal catalytic activity of the enzyme in this mutant was rapidly and reversibly inactivated at 28 degrees C. Using this mutant strain we show that cell movement in aggregates and mounds is organized by propagating waves of cAMP. Synergy experiments between wild-type and tsaca2 cells, shifted to the restrictive temperature at various stages of development, showed that ACA plays an important role in the control of cell sorting and tip formation.

Direct cleavage by the calcium-activated protease calpain can lead to inactivation of caspases

Caspases, a unique family of cysteine proteases involved in cytokine activation and in the execution of apoptosis can be sub-grouped according to the length of their prodomain. Long prodomain caspases such as caspase-8 and caspase-9 are believed to act mainly as upstream caspases to cleave downstream short prodomain caspases such as caspases-3 and -7. We report here the identification of caspases as direct substrates of calcium-activated proteases, calpains. Calpains cleave caspase-7 at sites distinct from those of the upstream caspases, generating proteolytically inactive fragments. Caspase-8 and caspase-9 can also be directly cleaved by calpains. Two calpain cleavage sites in caspase-9 have been identified by N-terminal sequencing of the cleaved products. Cleavage of caspase-9 by calpain generates truncated caspase-9 that is unable to activate caspase-3 in cell lysates. Furthermore, direct cleavage of caspase-9 by calpain blocks dATP and cytochrome-c induced caspase-3 activation. Therefore our results suggest that calpains may act as negative regulators of caspase processing and apoptosis by effectively inactivating upstream caspases.

[Study of graft-versus -leukemia activity of gamma-ray irradiated haplomismatched donor lymphocytes infusion]

OBJECTIVE

To explore graft-versus-leukemia activity of 7.5 Gy gamma-ray irradiated haplomismatched donor lymphocytes infusion (DLI).

METHODS

L615 cells loaded 615 (H2(k))/BALB/c (H-2(d)) F(1) mice were infused with irradiated haplo-mismatched donor lymphocytes at 3, 5, 7 days after CTX (200 mg/kg) treatment which was given at the 3rd day after L615 cells inoculation.

RESULTS

T-cells irradiated with 7.5 Gy gamma-ray lost their proliferative capacity but preserved their cytotoxic activity against allogeneic targets. Survival of these recipient mice was longer than that of control (t = 10.03, P < 0.001) with no severe graft-versus-host disease (GVHD).

CONCLUSION

7.5 Gy gamma irradiation attenuated the GVHD inducing potential of allogeneic lymphocytes while preserving their graft-versus-leukemia activity. It provides a simple modality to postpone and prevent leukemia relapse.

Stages in motion processing revealed by the ocular following response

Motion perception and associated involuntary eye movements depend on factors such as the physical attributes of the stimulus and visual attention. Cues from spatial changes in luminance (first-order motion in the Fourier domain) or more complicated transitions involving two-dimensional patterns (second-order, non-Fourier) require rather different kinds of analyses to detect their net motion. During a fixation task we monitored eye movements induced by the onset of motion to examine the functional properties of the monkey cortical motion processing system. Eye movement velocity was indistinguishable to first- and second-order motion; concomitant response latency confirmed an additional calculation is required to detect the direction and velocity of second-order motion.

Cortical evoked potentials due to motion contrast in the blind hemifield

Subcortical visual inputs to motion-selective cortex in primates survive after damage to the primary visual cortex (area 17/V1). Activation of human motion cortex was examined using scalp electrodes in a V1-damaged hemianope. Blind field motion-onset visual evoked potentials (VEPs) shared many of the characteristics associated with sighted vision but were smaller in amplitude and had longer latencies. The representative negative wave (C(II) peak) showed typical dependency on stimulus contrast, its peak latency increased and amplitude decreased as contrast decreased, reflecting the difficulty with which directional information could be detected. VEPs were present at contrasts below 25% when blind field motion was imperceptible even though direction guessing was paradoxically accurate. Subcortical inputs to motion cortex contribute to visual experience but not to conscious perception.

Vascular smooth muscle cell growth arrest on blockade of thrombospondin-1 requires p21(Cip1/WAF1)

Abnormal proliferation of vascular smooth muscle cells (VSMCs) is thought to play an important role in the pathogenesis of atherosclerosis and restenosis. Previous studies have implicated the extracellular matrix protein thrombospondin-1 (TSP1) in mitogen-dependent proliferation of VSMCs. In this study, we investigated the molecular mechanisms involved in TSP1-mediated regulation of VSMC growth. Neutralizing A4.1 anti-TSP1 antibody inhibited the activity of the G(1)/S cyclin-dependent kinase 2 (cdk2) and blocked the induction of S-phase entry, which normally occurs in serum-stimulated VSMCs. This growth-inhibitory effect was associated with a marked induction of p21(Cip1/WAF1) (p21) expression in A4.1-treated VSMCs. Moreover, addition of A4.1 antibody to VSMCs markedly increased the level of p21 bound to cdk2. Thus growth arrest on antibody blockade of TSP1 may be mediated by the cdk inhibitory protein p21. Consistent with this notion, anti-TSP1 antibody inhibited [(3)H]-thymidine incorporation in wild-type but not in p21-deficient mouse embryonic fibroblasts (MEFs). Together, these data suggest that p21 plays an important role in TSP1-mediated control of cellular proliferation.

The membrane association domain of RGS16 contains unique amphipathic features that are conserved in RGS4 and RGS5

Regulators of G protein signaling (RGS proteins) modulate G protein-mediated signaling pathways by acting as GTPase-activating proteins for Gi, Gq, and G12 alpha-subunits of heterotrimeric G proteins. Although it is known that membrane association is critical for the biological activities of many RGS proteins, the mechanism underlying this requirement remains unclear. We reported recently that the NH2 terminus of RGS16 is required for its function in vivo. In this study, we show that RGS16 lacking the NH2 terminus is no longer localized to the plasma membrane as is the wild type protein, suggesting that membrane association is important for biological function. The region of amino acids 7-32 is sufficient to confer the membrane-targeting activity, of which amino acids 12-30 are predicted to adopt an amphipathic alpha-helix. Site-directed mutagenesis experiments showed that the hydrophobic residues of the nonpolar face of the helix and the strips of positively charged side chains positioned along the polar/nonpolar interface of the helix are crucial for membrane association. Subcellular fractionation by differential centrifugation followed by conditions that distinguish peripheral membrane proteins from integral ones indicate that RGS16 is a peripheral membrane protein. We show further that RGS16 membrane association does not require palmitoylation. Our results, together with other recent findings, have defined a unique membrane association domain with amphipathic features. We believe that these structural features and the mechanism of membrane association of RGS16 are likely to apply to the homologous domains in RGS4 and RGS5.

Cell cycle withdrawal promotes myogenic induction of Akt, a positive modulator of myocyte survival

During myogenesis, proliferating myoblasts withdraw from the cell cycle, acquire an apoptosis-resistant phenotype, and differentiate into myotubes. Previous studies indicate that myogenic induction of the cyclin-dependent kinase inhibitor p21 results in an inhibition of apoptotic cell death in addition to its role as a negative cell cycle regulator. Here we demonstrate that the protein encoded by the Akt proto-oncogene is induced in C2C12 cells during myogenic differentiation with a corresponding increase in kinase activity. In differentiating cultures, expression of dominant-negative forms of Akt increase the frequency of cell death whereas expression of wild-type Akt protects against death, indicating that Akt is a positive modulator of myocyte survival. Antisense oligonucleotides against p21 block cell cycle withdrawal, inhibit Akt induction, and enhance cell death in differentiating myocyte cultures. Adenovirus-mediated transfer of wild-type or constitutively active Akt constructs confer partial resistance to cell death under conditions where cell cycle exit is blocked by the antisense oligonucleotides. Collectively, these data indicate that cell cycle withdrawal facilitates the induction of Akt during myogenesis, promoting myocyte survival.

A myb-related protein required for culmination in Dictyostelium

The avian retroviral v-myb gene and its cellular homologues throughout the animal and plant kingdoms contain a conserved DNA binding domain. We have isolated an insertional mutant of Dictyostelium unable to switch from slug migration to fruiting body formation i.e. unable to culminate. The gene that is disrupted, mybC, codes for a protein with a myb-like domain that is recognized by an antibody against the v-myb repeat domain. During development of myb+ cells, mybC is expressed only in prestalk cells. When developed together with wild-type cells mybC- cells are able to form both spores and stalk cells very efficiently. Their developmental defect is also bypassed by overexpressing cAMP-dependent protein kinase. However even when their defect is bypassed, mybC null slugs and culminates produce little if any of the intercellular signalling peptides SDF-1 and SDF-2 that are believed to be released by prestalk cells at culmination. We propose that the mybC gene product is required for an intercellular signaling process controlling maturation of stalk cells and spores and that SDF-1 and/or SDF-2 may be implicated in this process.

U.S. academic medical centers under the managed health care environment

This research investigates the impact of managed health care on academic medical centers in the United States. Academic medical centers hold a unique position in the U.S. health care system through their missions of conducting cutting-edge biomedical research, pursuing clinical and technological innovations, providing state-of-the-art medical care and producing highly qualified health professionals. However, policies to control costs through the use of managed care and limiting resources are detrimental to academic medical centers and impede the advancement of medical science. To survive the threats of managed care in the health care environment, academic medical centers must rely on their upper level managers to derive successful strategies. The methods used in this study include qualitative approaches in the form of key informants and case studies. In addition, a survey questionnaire was sent to 108 CEOs in all the academic medical centers in the U.S. The findings revealed that managers who perform the liaison, monitor, entrepreneur and resource allocator roles are crucial to ensure the survival of academic medical centers, so that academic medical centers can continue their missions to serve the general public and promote their well-being.

Isolation of spermidine synthase gene (spsA) of Dictyostelium discoideum

The gene encoding spermidine synthase (spsA) was isolated from Dictyostelium discoideum using the technique of insertional mutagenesis. Northern blot analysis showed that the spsA mRNA is expressed maximally during the vegetative stage and decreases gradually during the 24 h of development. Sequencing of the genomic DNA and a full-length cDNA clone indicated the presence of one intron in a gene coding for a predicted protein (SpsA) with 284 amino acids. The sequence is highly conserved, with amino acid identities compared to spermidine synthases of humans, 59.5%, to mouse, 61.3%, and to yeast, 58.1%. A null mutant of the spsA gene is unable to grow in the absence of exogenous spermidine. Development of spsA null cells grown in the absence of spermidine produced fruiting bodies that have abnormally short stalks.

Grating and plaid chrominance motion influences the suppressed ocular following response

Involuntary eye movements to foveal stimulation were measured in a monkey while it performed a fixation task. Second-order plaid motion generated higher velocities of eye movements than did first-order gratings, yet the latency of the early following response was no different for grating or plaid motion. Nevertheless, early suppressed ocular following responses to isoluminant motion continue to be titrated by stimulus velocity and spatial frequency. Motion defined by 60% luminance contrast gratings and plaids generated a motion signal gain of 60% over chrominance motion. The 20% longer latency of eye movements to chrominance motion may reflect the longer conduction latency of the parvocellular channel and an additional stage in cortical processing en route to motion areas and eye movement control.

Direction discrimination of moving gratings and plaids and coherence in dot displays without primary visual cortex (V1)

We present new experimental observations of G.Y., a well-tested patient with unilateral loss of primary visual cortex. We stimulated G.Y.'s blind hemifield using first- and second-order motion stimuli at velocities around psychophysical threshold. Using a dual response paradigm (awareness level of visual motion, motion direction discrimination) psychophysical performance improved with increasing velocity and dot coherence. We were also able to influence directly G.Y.'s performance for the better and at will, by placing the emphasis solely on direction discrimination. In the absence of V1, graduated detection and discrimination of stimuli known to activate both V1 and extrastriate motion areas MT/V5 and MST is still possible. These results are in line with residual visual processing but did not show evidence of unconscious processing of motion stimuli characteristic of 'blindsight'.

Short-latency ocular following of motion by monkeys during a fixation task

Short-latency ocular following responses in monkeys, induced by first- and second-order motion during a fixation task, were sensitive to stimulus size, retinal eccentricity and motion duration. Latency of eye movements was no different for first- or second-order motion and simply marked the occurrence of movement in the visual field. Second-order motion produced higher velocity eye movements than did first-order motion. The velocity of eye movements was influenced by the orientation of second-order pattern components as well as their conspicuous energy. Even when partially suppressed by a fixation task, involuntary eye movements during the initial pursuit remain sensitive to several properties of visual motion.

Involuntary eye movements in response to first- and second-order motion

We trained monkeys to maintain fixation while first- and second-order motion stimuli were displayed centrally in the visual field. Stimulus velocity, spatial frequency and contrast were varied to determine differences in patterns of involuntary eye movements elicited by random onset of stimulus motion. We observed different patterns of eye movement latency and velocity suggesting very early (< or = 100 ms) components of oculomotor activity are used to initiate smooth pursuit of object trajectory. Eye movement latency was insensitive to the complexity of stimulus motion, whereas second-order motion elicited faster eye movements than first-order motion. Instantaneous eye movement velocity might be related to the earliest stages of visual processing of component motion.

Residual motion discrimination using colour information without primary visual cortex

Previous studies have reported that some patients with damage to striate cortex retain the ability to detect monochromatic light and discriminate direction of achromatic movement in their blind visual fields. We investigated the residual chromatic visual capacity of a well-studied patient (GY) who has a unilateral lesion to striate cortex (V1). The data demonstrated that GY was able to detect and discriminate isoluminant colour targets presented in his blind hemifield. The velocity and contrast of chromatic moving stimuli affected GY's levels of conscious experience of movements he was able to discriminate. As the velocity or contrast was increased, his discrimination performance improved in line with rising visual awareness and judgement confidence. At isoluminance, GY continued to discriminate motion direction with above chance accuracy. These results indicate chromatic signals can also be used to process motion information in the absence of primary visual cortex.

[The general survey for chondromalacia of 2,743 Chinese population]

OBJECTIVE

To evaluate the distribution of chondromalacia patella in Chinese population.

METHODS

A random cluster sampling survey was performed covering 2,743 subjects varied in age, sex and occupation in 1995.

RESULTS

The prevalence rate is 36.2%. The occurrence in women was higher than that in men (P < 0.01), while in the age group, 30 to 39 years was the highest being 55.8%. The prevalence rate in soldier being 47.5% was the highest among varied occupations.

CONCLUSIONS

Our study is the first survey to be performed in a large number of Chinese population. This investigation may reflect the prevalence rate of chondromalacia patella in China.

Nitric oxide-induced downregulation of Cdk2 activity and cyclin A gene transcription in vascular smooth muscle cells

BACKGROUND

Nitric oxide (NO) inhibits vascular smooth muscle cell (VSMC) proliferation and neointima formation after balloon injury. However, the molecular mechanisms underlying NO-mediated growth arrest are poorly understood. In the present study, we examined the effects of the NO donors sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP) on cell cycle activity in VSMCs.

METHODS AND RESULTS

Stimulation of quiescent rat VSMCs with serum leads to an increase in cyclin-dependent kinase (cdk)2 kinase activity that correlates with a marked induction of cyclin A protein expression. The addition of SNP or SNAP to VSMC cultures at the time of serum stimulation abrogates the induction of cdk2 activity without suppressing protein levels of cdk2 or cyclin E. These NO donors block serum-stimulated upregulation of cyclin A mRNA and protein and repress the serum induction of cyclin A promoter activity in VSMCs.

CONCLUSIONS

The addition of the nitric oxide donors SNP or SNAP to mitogen-stimulated VSMCs prevents activation of cdk2, a key regulator of the G1 and S phases of the cell cycle. These NO donors do not affect the expression of cdk2 protein but block the mitogen-induced expression of cyclin A, an activating subunit of cdk2. SNP and SNAP also repress the mitogen-stimulated activation of the cyclin A promoter. These data suggest that the antiproliferative effect of NO on VSMCs results, at least in part, from the repression of cyclin A gene transcription.

Cellular composition and anatomic distribution in nonfunctioning pancreatic endocrine tumors: immunohistochemical study of 30 cases

OBJECTIVE

To investigate the cytological pattern and distribution in nonfunctioning pancreatic endocrine tumors.

METHODS

Using labeled streptavidin-biotin (LSAB), immunohistochemical staining for insulin, glucagon, somatostatin, pancreatic polypeptide and gastrin was performed on 30 nonfunctioning pancreatic endocrine tumors from 30 patients. The cellular composition and anatomic distribution in these tumors were analyzed.

RESULTS

Of 30 tumor tissues, 22 (73.3%) were found to contain cells immunoreactive to 1-4 kinds of peptide hormones; 17 (56.7%) showed positive staining for more than one peptide and up to 4 peptides; and 8 (26.7%) showed negative immunoreaction to all antiserum applied. No tumor was found to contain immunoreactive gastrin. Among 17 multihormonal tumors, 4 contained 2 kinds of peptide hormones, 8 had 3 kinds, and 5 harbored 4 kinds of peptide hormones. In addition, the difference in the number and type of positive endocrine cells between the tumors arising from the head of the pancreas and those arising from the body and tail of the pancreas were statistically significant (P < 0.05).

CONCLUSIONS

Immunohistochemically, the high positive rate to peptide hormones suggests that the nonfunctioning pancreatic endocrine tumors are actually not nonfunctioning; they are asymptomatic pancreatic endocrine tumors. Moreover, an uneven distribution of positive endocrine cells in the nonfunctioning pancreas endocrine tumors within the pancreas was identified.

Apoptosis-associated gene expression in the corpus luteum of the rat

The involution of the corpus luteum (CL) at parturition is an example of physiological apoptosis, a complex process involving massive vascular regression while luteal cells undergo apoptosis. In the present study, changes in gene expression associated with physiological apoptosis were examined. Three genes isolated in our laboratory because of their association with apoptotic processes in the ovary, mammary gland, and prostate served as the focus of our investigation: Y81, Gas-1, and the gene IAP encoding integrin-associated protein. Y81 is a novel gene for which three transcripts are apparent. A Y81 cDNA clone representing the longest transcript has been isolated; it shows an open reading frame exhibiting a region of very high homology with members of the frizzled family, the prototypes of which are cell autonomous polarity genes encoding seven-pass transmembrane receptor proteins, for example the receptor for Wingless. Gas-1 is known as a growth-arrest gene that inhibits DNA synthesis when microinjected into cells. Integrin-associated protein is a beta 3-integrin-binding protein for which, recently, a thrombo-spondin-binding activity has been recognized. These three genes, all sharply up-regulated in the course of physiological involution processes in the ovarian CL, in mammary gland, and in prostate, seem promising candidates-by virtue of their specific expression in distinct tissues undergoing programmed cell death-as mediators of stimuli leading to apoptosis and subsequent phagocytosis. In this study, sulfated glycoprotein-2, previously observed in many instances of physiological apoptosis, was further employed as an indicator for incipient apoptosis, and stromelysin was followed as a marker for the tissue remodeling activity that is intimately associated with apoptosis during involution.

[PCR in detecting the correlation between infection of HBV and cholelithiasis]

OBJECTIVE

To study the correlation between cholelithiasis and the infection of HBV.

METHOD

32 formalin-fixed and paraffin-embedded gallbladder samples of cholelithiasis patients and 20 gallbladder samples of non-cholelithiasis patients were investigated using the polymerase chain reaction-Ethidium bromide (PCR-EB) assay. The 52 patients were positive to HBV serologic markers.

RESULT

The results showed that HBV-DNA was found in 13 gallbladder samples of 32 cholelithiasis patients (40.63%), significantly higher than that in 3 gallbladder samples of 20 non-cholelithiasis patients (15%).

CONCLUSION

The infection of HBV and the formation of cholelithiasis are correlated.

[Expression of hepatitis C viral structure protein by recombinant vaccinia virus]

The hepatitis C viral (HCV) DNA fragment coding for the core and two glycoproteins E1 + E2/NS1 were inserted into vaccinia virus vector pJSA1175, under the control of the promoter 7.5K. 143TK- cells transfected with the HCV recombinant plasmid pJSA1175CE in the presence of infectious TK+ vaccinia virus (Tiantan stain) yielded recombinant vaccinia virus and expressed an approximately 90 kDa polyprotein. Southern blot hybridization showed that the inserted HCV cDNA was located at the vaccinia virus TK+ gene, J fragment. One polypeptide band between 106 and 80 kDa was revealed in SDS-PAGE which reacted with anti-core murine serum. The polypeptide could be secreted into the medium, the total amount was about the same as in the cells.

Isolation of myelin basic protein from whole tissue extracts by selective pH-dependent solubilization

A previous study of the selective solubility of myelin basic protein (MBP) of tissue extracts at pH 9.0 has raised issues of its quantitative recovery, and the differential solubility of its charge isomers. The pH-dependent solubility of proteins of acid extracts of delipidated tissue of bovine spinal cord was therefore reexamined. MBP of whole extracts was completely soluble up to pH 8.0 only, and less so by 25% at pH 9.0, and 43% at pH 10.0. The proteins other than MBP were virtually insoluble between pH 5.0 to 6.0, and 9.0 to 10.0. The solubility of the main charge isomers I to III of MBP of 18.5 kDa was found not to be affected by pH. Either pH 5.0 or 9.0 is therefore suitable for the selective isolation of MBP from whole tissue extracts, only pH 5.0 providing for the complete recovery of MBP. The pH-dependent solution behaviour was also examined following the separation of proteins of whole extracts by anion exchange chromatography at pH 10.4. Purified MBP and several related minor cationic components of lower molecular weight were soluble throughout. In contrast, the anionic proteins were only partly soluble between pH 4.0 to 10.0, i.e. by 4 to 20%. The results are consistent with specific protein-protein interactions of the proteins of whole extracts, either enhancing the solubility of non-MBP proteins, e.g. at pH 7.0, or impairing that of MBP between pH 8.0 to 10.0.