bluuebunny/crossref_metadata_2025 huggingface dataset:
Timing of SOX9 downregulation and female sex determination in gonads of the sea turtle Lepidochelys olivacea
Authors: Torres‐Maldonado Leda , Moreno‐Mendoza Norma , Landa Abraham , Merchant‐Larios Horacio
Published: August 2002

The SRY‐related gene SOX9 is involved in the differentiation of Sertoli cells in male gonads of vertebrates with different kinds of sex determination. In the olive ridley Lepidochelys olivacea, a species with temperature sex determination (TSD), the SOX9 protein is expressed at stages 21–24 in medullary cells in gonads of embryos incubated at both male‐(MPT) or female‐promoting temperatures (FPT). However, at FPT the expression of SOX9 protein decreases at stage 25 and disappears at stage 26, suggesting this as the critical period for SOX9 regulation by temperature. Here, we used reverse transcriptase polymerase chain reaction (RT‐PCR) to detect SOX9 transcripts in gonads of embryos switched from MPT to FPT at stage 23 and sampled at days 6–14. Simultaneously, groups of embryos were switched back to MPT and gonadal sex was established. SOX9 transcripts were detected at days 6–12 of switching, when embryos reached stage 25 and were no longer detected at day 14, when the embryos were at stage 26. Embryos switched back to MPT at days 6 or 8 formed testes, whereas embryos switched at days 10 or 14 developed ovaries. Results suggest that at MPT the male sex‐determining pathway that maintains SOX9 expression in male gonads is established at stage 24. In contrast, at FPT, the female sex‐determining pathway involved in downregulation of SOX9 in female gonads occurs within two days at stage 25. J. Exp. Zool. 290:498–503, 2001. © 2001 Wiley‐Liss, Inc.
Sperm surface proteases in ascidian fertilization
Authors: Lambert Charles C. , Someno Tetsuya , Sawada Hitoshi
Published: August 2002

Ascidian eggs are surrounded by a noncellular layer and two cellular layers, which are penetrated by sperm. Three sperm surface proteases are essential for fertilization of eggs from the stolidobranch ascidian Halocynthia: spermosin, acrosin, and the proteasome. In the phlebobranch Ciona, a chymotrypsin‐like protease and the proteasome are essential in fertilization. Sperm from the phlebobranch ascidians Phallusia mammillata, Ascidia (=Phallusia) nigra, and Ascidia columbiana, all express spermosin, acrosin, and the proteasomal chymotrypsin activities on their surfaces. Chymostatin blocks cleavage in phlebobranchs, but inhibitors of spermosin and acrosin only delay it by several minutes. Protease inhibitors have little effect upon sperm binding in Phallusia but strongly affect the rate of sperm passage through the vitelline coat. Peptide substrates and inhibitors to spermosin and acrosin cause a significant decline in the number of eggs undergoing pre‐meiotic contractions at 3 min after fertilization. Thus while chymotrypsin activity is essential for penetration of the vitelline coat, spermosin and acrosin both function to increase the rate of fertilization. A crucial step in the divergence of the phlebobranchs and stolidobranchs may have been the conversion of spermosin and acrosin to essential proteases in the stolidobranchs, or, perhaps, their essential function was lost in the evolution of phlebobranchs. Aplousobranch ascidians are all colonial with very small zooids. Sperm from Aplidium californicum, Aplidium solidum (Polyclinidae), and Distaplia occidentalis (Holozoidae) have acrosin and chymotrypsin activities but lack spermosin activity. This enzyme is also missing from sperm of colonial phlebobranch and stolidobranch ascidians, suggesting that spermosin is not necessary for small zooids with internal fertilization. J. Exp. Zool. 292:88–95, 2002. © 2002 Wiley‐Liss, Inc.
Forbidden subgraphs that imply hamiltonian‐connectedness*
Authors: Broersma Hajo , Faudree Ralph J. , Huck Andreas , Trommel Huib , Veldman Henk Jan
Published: August 2002

It is proven that if G is a 3‐connected claw‐free graph which is also H1‐free (where H1 consists of two disjoint triangles connected by an edge), then G is hamiltonian‐connected. Also, examples will be described that determine a finite family of graphs ${\cal L}$ such that if a 3‐connected graph being claw‐free and L‐free implies G is hamiltonian‐connected, then L $\in \cal L$. © 2002 Wiley Periodicals, Inc. J Graph Theory 40: 104–119, 2002
Attacking Poverty and the ‘post‐Washington consensus’
Authors: Mosley Paul
Published: August 2002

Has the increasingly pro‐poor stance of the World Bank, as manifested in particular in its most recent World Development Report (WDR), caused it to abandon its traditionally free‐market attitudes ? The answer is ‘yes and no’. The pursuit of ‘security’ espoused by the WDR has forced the Bank to acknowledge widespread market failure in the provision of security, both social and financial; and this has caused the Bank to espouse some measures very inconsistent with the Washington consensus, such as international capital controls. On the other hand, the old agenda of rolling back the frontiers of the state remains, and is given a new twist in WDR 2000 by the revelation that the ‘voices of the poor’ are arrayed against bureaucratic abuses. Debate within the Bank has become much more open and transparent, and this has exposed long‐persisting internal differences about what markets still need to be liberalized in what environments. Copyright © 2001 John Wiley & Sons, Ltd.
From social networks to public action in urban governance: where does benefit accrue?
Authors: Beall Jo
Published: August 2002

The key question addressed in this paper is in what ways strategies at the community level make a difference to urban governance and for whom? The research on which it draws was concerned with two issues of relevance. The first was what poor people and communities do for themselves when city governments are unable or unwilling to extend resources to them. The second was to understand the institutional relationships, both formal and informal, between people in poverty and the organizations of city governance. In addition to local government, business and NGOs, these are understood to include associations of mutuality and community level organizations, particularly households, social networks, and political and developmental CBOs (see also Beall and Kanji, 1999). Drawing on research conducted in the nine case study cities, evidence of local level networks and associational life is examined to assess where benefits accrue when they are harnessed in the interests of city governance. These are very different cities and livelihood strategies and patterns of public action and urban governance are undoubtedly context‐specific. However, patterns emerge that are comparable and worthy of comment. Copyright © 2001 John Wiley & Sons, Ltd.
Morphology of the prometamorphic larva of the spadefoot toad, Scaphiopus intermontanus (Anura: Pelobatidae), with an emphasis on the lateral line system and mouthparts
Authors: Hall John A. , Larsen John H. , Fitzner Richard E.
Published: August 2002

We provide a detailed description of the larval morphology of the Great Basin spadefoot toad (Scaphiopus intermontanus), a species with documented morphological variability in larval structures associated with feeding. We based our findings on laboratory‐raised individuals fed a herbivorous diet. We characterized the morphology of the prometamorphic larva (limited to developmental stages 37 and 38) and then related our findings to the larval ecology of the species. Based on its morphology, such as slightly depressed body, dorsally positioned eyes, anteroventrally oriented oral disc, intermediate tail fin height and slightly attenuated tail tip, relative lack of ventral neuromasts (compared to Xenopus laevis), and pigmentation banding patterns, and habits, such as selection of breeding sites by adults and larval foraging behavior, S. intermontanus can be characterized best as belonging to a (lentic‐) benthic guild of anuran larvae. Nevertheless, the larvae are capable of occupying a broader array of ecological niches. Because we characterized individuals raised on a herbivorous diet, our morphological descriptions apply only to the herbivorous S. intermontanus larva (and perhaps to those larvae that are dietary generalists and may feed carnivorously only infrequently). Our findings can serve as a baseline for future morphological and developmental comparisons with the carnivorous morphological variant of this species. J. Morphol. 252:114–130, 2002. © 2002 Wiley‐Liss, Inc.
Placentation in garter snakes: Scanning EM of the placental membranes of Thamnophis ordinoides and T. sirtalis
Authors: Blackburn Daniel G. , Stewart James R. , Baxter Duane C. , Hoffman Loren H.
Published: August 2002

Surface topography and cross‐sections of the placental membranes were examined by scanning electron microscopy in two species of Thamnophis. The chorionic epithelium of the chorioallantoic placenta consists of broad, squamous cells that lack surface specializations. The apposed uterine epithelium contains ciliated cells and larger, nonciliated cells. Neither the epithelium of the chorion nor that of the uterus is eroded; thus, underlying capillaries are not exposed to the luminal surface. In both the omphaloplacenta and the omphalallantoic placenta, epithelium of the omphalopleure consists of brush‐border cells bearing prominent microvilli, interspersed with cells bearing minuscule microvilli. These surface epithelial cells are joined at their apices and their lateral surfaces are extensively sculpted by intercellular channels, presenting the appearance of an epithelium specialized for absorption. Deep to the epithelium lie the yolk spheres of the isolated yolk mass, interspersed with endodermal cells. Surface topography of the uterine epithelia of the omphaloplacenta and omphalallantoic placenta is relatively unspecialized. The acellular shell membrane separates maternal and fetal tissues in each of the three placental types. Marked differences in surface features of the chorioallantois and omphalopleure probably reflect different roles of these membranes in gas exchange and transfer of water and nutrients. J. Morphol. 252:263–275, 2002. © 2002 Wiley‐Liss, Inc.
Collateral flow in coarctation of the aorta with magnetic resonance velocity mapping: Correlation to morphological imaging of collateral vessels
Authors: Holmqvist Catarina , Ståhlberg Freddy , Hanséus Katarina , Hochbergs Peter , Sandström Staffan , Larsson Elna‐Marie , Laurin Sven
Published: August 2002

Purpose

To correlate quantification of collateral flow in aortic coarctation with the morphological visualization of the collateral vessels and to compare different approaches to measurement of collateral flow.

Materials and Methods

Thirteen children with coarctation were examined with T1‐weighted spin‐echo (T1‐W SE) imaging and 3D contrast‐enhanced magnetic resonance angiography (MRA). MR velocity mapping was performed at four levels in the descending aorta.

Results

The flow immediately above and below the coarctation did not differ significantly. Measuring within the coarctation resulted in flow overestimation. The increase of flow from proximal to distal aorta was 12 ± 21% in patients with no or uncertain collaterals and 69 ± 55% in patients with pronounced collaterals. Spin‐echo images and MRA were comparable in visualizing collateral vessels. The visual estimation of collaterals correlated reasonably well with flow quantification MR velocity mapping.

Conclusion

Collateral flow assessment with MR velocity mapping is an accurate technique for evaluating the hemodynamic importance of a coarctation and is recommended if abundant collaterals are not visualized with spin echo or MRA. J. Magn. Reson. Imaging 2002;15:39–46. © 2002 Wiley‐Liss, Inc.
Three‐dimensional true‐FISP imaging of the coronary arteries: Improved contrast with T2‐preparation
Authors: Shea Steven M. , Deshpande Vibhas S. , Chung Yiu‐Cho , Li Debiao
Published: August 2002

Purpose

To evaluate the effectiveness of a T2‐magnetization preparation scheme for improving coronary artery imaging with true fast imaging with steady‐state precession (True‐FISP).

Materials and Methods

Simulations were performed to compare the blood‐myocardium signal difference with no T2‐preparation to that with various T2‐preparation times (24, 40, and 60 msec) using an electrocardiogram (ECG)‐triggered, segmented True‐FISP acquisition. Seven volunteers were imaged to evaluate the effectiveness of T2‐preparation for coronary artery delineation using True‐ FISP and to optimize the T2‐preparation time.

Results

Simulations showed that T2‐preparation improved the signal difference between blood and myocardium over that without T2‐preparation. The optimal T2‐ preparation time was determined to be 40 msec. In volunteer studies, a T2‐ preparation time of 40 msec provided a significant improvement in contrast‐ to‐noise ratio (CNR) between the coronary arteries and myocardium over that without T2‐preparation. It also showed a significant improvement in visualizing the distal portions of the coronary arteries.

Conclusion

T2‐preparation improves coronary artery delineation with True‐FISP. J. Magn. Reson. Imaging 2002;15:597–602. © 2002 Wiley‐Liss, Inc.
A targeted contrast agent for magnetic resonance imaging of thrombus: Implications of spatial resolution
Authors: Johansson L.O. , Bjørnerud A. , Ahlström H.K , Ladd D.L. , Fujii D.K.
Published: August 2002

A preparation of ultra‐small superparamagnetic iron oxide (USPIO) particles coupled to an RGD peptide (RGD‐USPIO) was investigated as an MR contrast agent, targeted to activated platelets, in both ex vivo and in vivo thrombus models. Thrombus visualization ex vivo was compared using RGD‐USPIO and a non‐targeted UPSIO. The influence of thrombus visualization on thrombus exposure time to RGD‐USPIO (ex vivo) and on the spatial resolution of the MR image (ex vivo and in vivo) was assessed. RGD‐USPIO resulted in better thrombus visualization than non‐targeted USPIO ex vivo, and maximum enhancement was achieved after approximately one hour exposure time of the thrombus to RGD‐USPIO. The ability to visualize the clots was highly dependent on the spatial resolution of the image. In vivo, an in‐plane resolution of less than 0.2 × 0.2 mm2 was required for good clot visualization after contrast enhancement. It is concluded that the achievable resolution and sensitivity is a potential limitation to the usefulness of active vascular targeting in MRI. J. Magn. Reson. Imaging 2001;13:615–618. © 2001 Wiley‐Liss, Inc.
Changes in intrarenal oxygenation as evaluated by BOLD MRI in a rat kidney model for radiocontrast nephropathy
Authors: Prasad Pottumarthi V. , Priatna Agus , Spokes Katherine , Epstein Franklin H.
Published: August 2002

The pathogenesis of radiocontrast nephropathy is poorly understood. In an animal model, inhibition of the synthesis of nitric oxide and prostaglandins appears to predispose rats to severe renal injury following the administration of radiocontrast. Here we have investigated whether administration of radiocontrast, as well as changes in renal medullary oxygenation following pharmacologic inhibition of nitric oxide and prostaglandin synthesis, might be evaluated by blood oxygenation level‐dependent (BOLD) MRI. Nineteen anesthetized (Inactin 100 mg/kg) rats were studied. BOLD MRI measurements were performed following administration of L‐NAME (N‐nitro‐L‐arginine methyl ester, 10 mg/kg), Indomethacin (10 mg/kg), and a radiocontrast agent (sodium iothalamate 60%, 6 mL/kg). Marked sequential changes in medullary R, presumably reflecting decline in medullary pO2, were noted after each of the pharmacological interventions employed. These results, obtained by noninvasive MRI, are consistent with prior direct recordings of pO2 and doppler flow in the rat renal medulla after administration of L‐NAME, Indomethacin and iothalamate. Medullary oxygenation in rats was reduced by inhibition of the synthesis of prostaglandins and nitric oxide, as well as by intravenous injection of radiocontrast agents. BOLD MRI can noninvasively evaluate changes in medullary oxygenation in rats that appear to predispose acute renal failure. J. Magn. Reson. Imaging 2001;13:744–747. © 2001 Wiley‐Liss, Inc.
An integrated visualization system for surgical planning and guidance using image fusion and an open MR
Authors: Gering David T. , Nabavi Arya , Kikinis Ron , Hata Noby , O'Donnell Lauren J. , Grimson W. Eric L. , Jolesz Ferenc A. , Black Peter M. , Wells William M.
Published: August 2002

A surgical guidance and visualization system is presented, which uniquely integrates capabilities for data analysis and on‐line interventional guidance into the setting of interventional MRI. Various pre‐operative scans (T1‐ and T2‐weighted MRI, MR angiography, and functional MRI (fMRI)) are fused and automatically aligned with the operating field of the interventional MR system. Both pre‐surgical and intra‐operative data may be segmented to generate three‐dimensional surface models of key anatomical and functional structures. Models are combined in a three‐dimensional scene along with reformatted slices that are driven by a tracked surgical device. Thus, pre‐operative data augments interventional imaging to expedite tissue characterization and precise localization and targeting. As the surgery progresses, and anatomical changes subsequently reduce the relevance of pre‐operative data, interventional data is refreshed for software navigation in true real time. The system has been applied in 45 neurosurgical cases and found to have beneficial utility for planning and guidance. J. Magn. Reson. Imaging 2001;13:967–975. © 2001 Wiley‐Liss, Inc.
Extent and time course of morphological changes of bone marrow induced by granulocyte‐colony stimulating factor as assessed by magnetic resonance imaging of healthy blood stem cell donors
Authors: Altehoefer Carsten , Bertz Hartmut , Ghanem Nadir A. , Langer Mathias
Published: August 2002

The aim of this study was to assess the time course and extent of signal alterations of red bone marrow after short‐term stimulation by recombinant human granulocyte‐colony stimulating factor (rHuG‐CSF) in healthy peripheral blood stem cell donors using magnetic resonance imaging (MRI) at low‐field strength. Twelve healthy blood stem cell donors without evidence of bone marrow disorders were prospectively investigated and underwent four MRI studies of their lumbar spine. Sagittal T1‐ and T2‐weighted spin‐echo sequences and a gradient‐echo (GE) sequence with an echo time for out‐of‐phase imaging were performed prior to rHuG‐CSF application (baseline MRI), on the day of first stem cell harvest (after 70 μg/kg body weight rHuG‐CSF, second MRI) followed by two studies 9–18 days (median 14.5 days, third MRI) and 26–48 days (median 39.5 days, fourth MRI) after discontinuation of rHuG‐CSF application. Baseline MRI showed normal marrow signal in all patients. The second MRI revealed a decrease of quantified bone marrow signal relative to nucleus pulposus in T1‐ and T2‐weighted images and an increase of relative signal in out‐of‐phase GE sequences. The greatest changes of relative marrow signal were observed at the third MRI. Compared to baseline MRI, relative marrow signal was diminished by 12% in T1‐weighted images and increased by 59% in GE sequences, consistent with a rise in marrow cellularity simulating diffuse marrow disease. At the fourth MRI quantified relative marrow signal returned to baseline levels in all sequences. In healthy individuals rHuG‐CSF application leads to significant signal changes of bone marrow in lumbar vertebra that are maximal about 2 weeks after discontinuation of rHuG‐CSF application. In patients with underlying marrow disorders who receive hematopoietic growth factors during treatment, these changes should not be confused with disease progression. J. Magn. Reson. Imaging 2001;14:141–146. © 2001 Wiley‐Liss, Inc.
Impact of bulk cardiac motion on right coronary MR angiography and vessel wall imaging
Authors: Kim W. Yong , Stuber Matthias , Kissinger Kraig V. , Andersen Niels Trolle , Manning Warren J. , Botnar René M.
Published: August 2002

The purpose of this study was to investigate the impact of in‐plane coronary artery motion on coronary magnetic resonance angiography (MRA) and coronary MR vessel wall imaging. Free‐breathing, navigator‐gated, 3D‐segmented k‐space turbo field echo ((TFE)/echo‐planar imaging (EPI)) coronary MRA and 2D fast spin‐echo coronary vessel wall imaging of the right coronary artery (RCA) were performed in 15 healthy adult subjects. Images were acquired at two different diastolic time periods in each subject: 1) during a subject‐specific diastasis period (in‐plane velocity <4 cm/second) identified from analysis of in‐plane coronary artery motion, and 2) using a diastolic trigger delay based on a previously implemented heart‐rate‐dependent empirical formula. RCA vessel wall imaging was only feasible with subject‐specific middiastolic acquisition, while the coronary wall could not be identified with the heart‐rate‐dependent formula. For coronary MRA, RCA border definition was improved by 13% (P < 0.001) with the use of subject‐specific trigger delay (vs. heart‐rate‐dependent delay). Subject‐specific middiastolic image acquisition improves 3D TFE/EPI coronary MRA, and is critical for RCA vessel wall imaging. J. Magn. Reson. Imaging 2001;14:383–390. © 2001 Wiley‐Liss, Inc.
Magnetic resonance myocardial first‐pass perfusion imaging: Parameter optimization for signal response and cardiac coverage
Authors: Bertschinger Katharina M. , Nanz Daniel , Buechi Martin , Luescher Thomas F. , Marincek Borut , von Schulthess Gustav K. , Schwitter Juerg
Published: August 2002

Fast imaging techniques allow monitoring of contrast medium (CM) first‐pass kinetics in a multislice mode. Employing shorter recovery times improves cardiac coverage during first‐pass conditions, but potentially flattens signal response in the myocardium. The aim of this study was therefore to compare in patients with suspected coronary artery disease (CAD) two echo‐planar imaging strategies yielding either extended cardiac coverage or optimized myocardial signal response (protocol A/B, six/four slices; preparation pulse, 60°/90°; delay time, 10/120 msec; readout flip angle, 10°/50°; respectively). In phantoms and myocardium of normal volunteers (N= 10) the CM‐induced signal increase was 2.5–3 times higher with protocol B (P < 0.005) than with protocol A. For the detection of individually diseased coronary arteries (≥1 stenosis with ≥50% diameter reduction on quantitative coronary angiography (QCA)), receiver‐operator characteristics of protocol B (signal upslope in 32 sectors/heart) yielded a sensitivity/specificity of 82%/73%, which was superior to protocol A (P < 0.05, N= 14). For the overall detection of CAD, the sensitivity/specificity of protocol B was 85%/81%. An adequate signal response in the myocardium is crucial for a reliable detection of perfusion deficits during first‐pass conditions. The presented protocol B detects CAD with a sensitivity and specificity similar to scintigraphic techniques. J. Magn. Reson. Imaging 2001;14:556–562. © 2001 Wiley‐Liss, Inc.
Interfaces for coupled liquid‐phase separation/mass spectrometry techniques. An update on recent developments
Authors: Gelpí Emilio
Published: August 2002

An update is presented covering the latest developments in the interfacing of liquid‐phase separation systems and mass spectrometers. The interfacing devices presented are those developed for continuous‐flow matrix‐assisted laser desorption/ionization, micro‐ and nano‐liquid chromatography/masspectrometry (MS), capillary electrophoresis/MS and on‐chip separation technologies/MS. From the information that can be found in the most recent literature on the topic, it is evident that the trend towards the miniaturization of separation and interface devices is gaining ground. This can be rationalized by the substantial gains in sensitivity for the detection and study of extremely low levels of analytes and especially of high molecular mass biopolymers. Copyright © 2002 John Wiley & Sons, Ltd.
Prevalence and distribution of human herpesvirus 6 variants A and B in adult human brain
Authors: Chan Paul K.S. , Ng Ho‐Keung , Hui Mamie , Cheng Augustine F.
Published: August 2002

The presence of human herpesvirus 6 (HHV‐6) in brain tissues of 40 consecutive post‐mortem cases was examined. For each case, autopsy samples were collected from the cerebellum, frontal, temporal, parietal and occipital lobes of both sides of the brain. HHV‐6 DNA was detected by nested polymerase chain reaction and characterised into variants A and B. Overall, 97/400 (24.3%) samples were positive for HHV‐6 DNA with 16 being variant A and 81 being variant B, but none of the samples harboured both variants. When analysed by patient, 34/40 (85%) had HHV‐6 DNA detected in the brain. The viral DNA positivity did not show significant variation with gender and age. Four patients harboured variant A, 23 harboured variant B, and seven had both variants at different positions. The results indicate that both HHV‐6A and HHV‐6B are neurotropic and human brain may be another site for latency. HHV‐6B was detected in brain tissues of a majority (75%) of the studied population and with a widespread distribution within the brain. Although the observed prevalence of HHV‐6A in brain is lower (27.5%), in view of its lower seroprevalence, the neuroinvasive potential of variant A may be comparable to that of variant B. Although both variants are potential pathogens for the nervous system, the fact that they can exist, probably for most of the time, as commensals in human brain needs to be considered when interpreting their roles in neuropathology. J. Med. Virol. 64:42–46, 2001. © 2001 Wiley‐Liss, Inc.
CV genotype and “silent” HBV coinfection: Two main risk factors for a more severe liver disease
Authors: Sagnelli Evangelista , Coppola Nicola , Scolastico Carlo , Mogavero Anna Rita , Filippini Pietro , Piccinino Felice
Published: August 2002

To evaluate whether HCV genotype and a “silent” HBV infection may be related to a more severe clinical presentation of liver disease, 205 anti‐HCV/HCV‐RNA positive, HBsAg/anti‐HBs negative patients with chronic hepatitis (113 males and 92 females; median age 55 years, range 18–77), were studied on presentation at the Liver Unit from January 1993 to December 1997. Presence of serum anti‐HBc, in the absence of HBsAg and anti‐HBs, was considered a marker of “silent” HBV infection. Of the 205 patients, 134 had undergone percutaneous liver biopsy. Two main diagnosis groups were established: the mild liver disease group (76 patients), and the severe liver disease group (109 patients); 20 patients who had refused to undergo liver biopsy were not included in the clinical and virological evaluation because the diagnosis was uncertain. The prevalence of severe liver disease was similar in the genotype 1 and non‐1 groups (61.3% of 98 patients with genotype 1 and 52.9% of 70 patients with a non‐1 genotype). Instead, the 88 patients with “silent” HBV infection showed a higher percentage of severe liver disease than the 97 anti‐HBc negative patients (72.7% vs. 46.4%, respectively: P < 0.0005). Of the 88 anti‐HBc positive patients, the prevalence of those with severe liver disease was similar in the 32 cases with serum HBV‐DNA as detected by PCR and in the 56 HBV‐DNA negative (81.2% vs. 67.8%, P = 0.4). The relation between “silent” HBV infection and severe liver disease was observed both in genotype 1 and non‐1 infected patients. Nevertheless, the anti‐HBc negative patients infected by genotype 1 showed a severe liver disease more frequently than those infected by a non‐1 genotype, with a difference that is significant to the statistical analysis (P < 0.05). The findings suggest that “silent” HBV infection in anti‐HCV positive chronic hepatitis enhances the severity of the liver disease. Evidence was also found that in patients without “silent” HBV infection there is a correlation between the presence of HCV genotype 1 and the severity of liver disease. J. Med. Virol. 64:350–355, 2001. © 2001 Wiley‐Liss, Inc.
High prevalence of TT virus‐related DNA (90%) and diverse viral genotypes in norwegian blood donors
Authors: Huang Li‐Yue , Jonassen Tom Øystein , Hungnes Olav , Grinde Bjørn
Published: August 2002

Early estimates of the prevalence of TTV viremia in healthy adults of developed countries were in the order of 1–10 %, while similar estimates in Third World countries were considerably higher. Using three different PCRs, TTV‐related DNA was detected in serum from 180 out of the 201 Norwegian blood donors tested, indicating that these viruses are almost universally present in adults. Sequence analysis revealed heterogeneity similar to what is found world‐wide. The data suggest that the previous discrepancy in prevalences might be related to a lower serum concentration of virus in developed countries. The high prevalence adds evidence to the benign nature of the virus. J. Med. Virol. 64:381–386, 2001. © 2001 Wiley‐Liss, Inc.
Development and significance of resistance to protease inhibitors in HIV‐1‐infected adults under triple‐drug therapy in clinical practice
Authors: Romano Laura , Venturi Giulietta , Giomi Saverio , Pippi Luigi , Valensin Pier E. , Zazzi Maurizio
Published: August 2002

Development of drug resistance is considered a major cause for failure of antiretroviral therapy in human immunodeficiency virus type 1 (HIV‐1)‐infected patients adherent to treatment. However, the rate of emergence and the significance of HIV‐1 drug resistance in clinical practice have been not investigated thoroughly. Selection of HIV‐1 variants that are genotypically resistant to protease inhibitors was studied in all the patients (n = 169) who completed at least 18 months of treatment with a protease inhibitor plus two nucleoside reverse transcriptase inhibitors at two urban Italian hospitals. HIV‐1 carrying primary protease inhibitor resistance mutations was detected in 70 (41.4%) patients. The estimated proportion of patients developing genotypic resistance to protease inhibitors at 12 and 24 months was 18.3% (95% CI, 12.5–24.2%) and 33.9% (95% CI, 26.4–41.5%), respectively. Independent predictors of development of resistance to protease inhibitors were higher HIV‐1 RNA levels at the nadir (P < 0.0001) and inclusion of ritonavir or saquinavir versus indinavir in the starting regimen (P = 0.0313). Resistance to protease inhibitors was strongly associated with a lower response to treatment, as shown by HIV‐1 RNA load (P = 0.0001) and CD4 cell counts (P = 0.005). However, a linear increase in CD4 cell counts was maintained up to the end of follow‐up even in the protease inhibitor‐resistant population. Resistance to protease inhibitors develops in a relevant proportion of patients under long‐term triple‐drug therapy in clinical practice and is associated with virological treatment failure and limitation of CD4 cell increase. J. Med. Virol. 66:143–150, 2002. © 2002 Wiley‐Liss, Inc.
Hepatitis C virus NS4A and NS4B proteins suppress translation in vivo
Authors: Kato Jun , Kato Naoya , Yoshida Hideo , Ono‐Nita Suzane Kioko , Shiratori Yasushi , Omata Masao
Published: August 2002

Many viruses can inhibit protein synthesis in their host cells by targeting translation (“translational shutoff”). There are few reports on the effects of hepatitis C virus (HCV) infection on protein synthesis, because of the lack of a reproducible tissue culture system for HCV. In this study, the influence of seven HCV proteins (core, NS2, NS3, NS4A, NS4B, NS5A, NS5B) on protein synthesis was examined using a reporter assay. In addition, it was determined whether the HCV proteins inhibit protein synthesis via transcription or translation using an RNase protection assay and the effect of HCV proteins on translation from the HCV internal ribosome entry site (IRES) was also examined using a bicistronic reporter. Of the seven HCV proteins, NS4A and NS4B proteins inhibited cellular protein synthesis by targeting the process of translation. They also inhibited translation from the HCV IRES. Moreover, NS4A protein, induced under the control of doxycycline, inhibited the proliferation of HeLa cells. In conclusion, HCV NS4A and NS4B proteins have an effect of translational inhibition. This novel function may be involved in HCV infection and help its survival in host cells. J. Med. Virol. 66:187–199, 2002. © 2002 Wiley‐Liss, Inc.
Effect of ethanol on the metabolism of primary astrocytes studied by 13C‐ and 31P‐NMR spectroscopy
Authors: Fonseca Luís L. , Alves Paula M. , Carrondo Manuel J.T. , Santos Helena
Published: August 2002

Nuclear magnetic resonance was used as the primary technique to investigate the effect of ethanol (40, 80, and 160 mM) on the levels of high‐energy phosphates, glycolytic flux, anaplerotic and oxidative fluxes to the tricarboxylic acid (TCA) cycle, the contribution of the pentose phosphate pathway (PPP), and the uptake and release of amino acids on primary cultures of rat astrocytes. On line 31P‐NMR spectroscopy showed that long‐term exposure to ethanol caused a drop in the levels of ATP and phosphocreatine. The ratio between the fluxes through the pyruvate dehydrogenase and pyruvate carboxylase reactions also decreased, whereas the glycolytic flux and the ratio between formation of lactate and glucose consumption increased when cells were exposed to acute doses of ethanol. Flux through the pentose phosphate pathway was not affected. The uptake of cysteine and the release of glutamine were stimulated by ethanol, whereas the release of methionine was inhibited. Moreover, the fractional enrichment in serine was enhanced. The changes in the amino acid metabolism are interpreted as a response to oxidative stress induced by ethanol. © 2001 Wiley‐Liss, Inc.
Retinoic acid increases proliferation rate of GL‐15 glioma cells, involving activation of STAT‐3 transcription factor
Authors: Paillaud E. , Costa S. , Fages C. , Plassat J.L. , Rochette‐Egly C. , Monville C. , Tardy M.
Published: August 2002

The molecular mechanisms underlying the heterogeneous effects of retinoic acid (RA) treatment on malignant glioma cells remain poorly understood. In this study, we present the first evidence of a functional role of the signal transduction factors (STATs) in RA‐induced proliferation, in a human glioblastoma GL‐15 cell line. We first observed that STAT‐3 was constitutively activated and present in the GL‐15 cell nuclei. We then showed that at low doses (0.01–1 μM) RA increased both the proliferation rate of GL‐15 cells and the phosphotyrosine (PY) activation of STAT‐3. This RA effect involved transcriptional processes and the transactivation of RA target genes, including RA receptors isoforms RARα2, ‐β2, and ‐γ2. At higher concentrations, however, RA (5–10 μM) inhibits GL‐15 proliferation, induces apoptosis, and fails to activate STAT‐3. An inhibitory effect on GL‐15 proliferation was also observed with the synthetic retinoids CD‐437 and CD‐2325, two structurally related RARγ agonists, which also fail to activate STAT‐3. In addition, the phorbol ester PMA, an inducer of GL‐15 differentiation, and staurosporine, a broad inhibitor of protein kinases, abrogate the stimulatory effects of RA at low concentrations. Together these observations suggest that, in GL‐15 cells, activation of STAT‐3 and cell proliferation share common mechanisms and that STAT transcription factors may be involved in a switch between proliferation, differentiation, and apoptosis. The proliferating effect observed at low doses of RA may be related to the failures in RA efficiency observed in clinical assays in relapsing malignant gliomas. Combining specific inhibitors of tyrosine kinases with RA might optimize the clinical outcome. © 2002 Wiley‐Liss, Inc.
Secreted phospholipase A2 potentiates glutamate‐induced calcium increase and cell death in primary neuronal cultures
Authors: DeCoster Mark A. , Lambeau Gerard , Lazdunski Michel , Bazan Nicolas G.
Published: August 2002

Secreted phospholipases A2 (sPLA2s) modulate neuronal survival and neurotransmitter release. Here we show that sPLA2 (group III) synergistically increases glutamate‐induced cell death and intracellular calcium ([Ca2+]i) in cultured primary cortical and hippocampal neurons. Whereas 1 μM glutamate elicited transient [Ca2+]i increases in all neurons that recovered 66% to baseline, 25 ng/ml sPLA2 pretreatment resulted in sustained [Ca2+]i increases, with only 5% recovery. At 250 nM glutamate, 25% of neurons failed to respond, and the average recovery time was 101 ± 12 sec; sPLA2 increased recovery time to 158 ± 6 sec, and only 2% of cells failed to respond. Both the noncompetitive N‐methyl‐D‐aspartate (NMDA) receptor antagonist MK‐801 and the calcium‐channel blocker cobalt inhibited this effect. Experiments with the glutamate uptake inhibitor L‐trans‐pyrollidine‐2,4‐dicarboxylic acid (2.5 μM) indicated that glutamate uptake sites are not a likely modulation point by sPLA2, whereas arachidonic acid (AA) potentiated calcium responses to glutamate. Thus the enhancement of glutamate‐induced [Ca2+]i increases by sPLA2 may be due to modulation at NMDA receptors and/or calcium channels by AA. These results indicate that sPLA2 affects neuronal responses to both nontoxic (0.1–10 μM) and toxic (=25 μM) concentrations of glutamate, implicating this enzyme in neuronal functions in pathology. © 2002 Wiley‐Liss, Inc.
Nogos and the Nogo‐66 receptor: Factors inhibiting CNS neuron regeneration
Authors: Ng Cherry Ee Lin , Tang Bor Luen
Published: August 2002

The recently cloned gene Nogo, whose alternative splice products correspond to the antigenic target of the central nervous system (CNS) regeneration enhancing monoclonal antibody IN‐1, codes for membrane proteins enriched in brain, particularly in oligodendrocytes. The 66‐amino acid extracellular domain of Nogo (Nogo‐66) interacts with a high‐affinity receptor (NgR), a glycosylphosphatidylinositol (GPI)‐linked protein with multiple leucine‐rich repeats. The amino terminal cytoplasmic domain of Nogo appears to have a general cellular growth inhibitory effect. Nogo‐66, on the other hand, specifically retards neurite outgrowth and induces growth cone collapse, possibly through its interaction with NgR and as yet unidentified transmembrane coreceptors. Recent results also suggest that Nogo expression may induce apoptosis in tumor cells. Together, these proteins provide new molecular handles for the design of therapeutic interventions for CNS injuries and neurodegenerative diseases, as well as possible leads to anticancer strategies. © 2002 Wiley‐Liss, Inc.
Visual responses of neurons in the nucleus of the basal optic root to stationary stimuli in pigeons
Authors: Gu Yong , Wang Yuan , Wang Shu‐Rong
Published: August 2002

The nucleus of the basal optic root of the accessory optic system in pigeons is involved in generating optokinetic nystagmus, which stabilizes object images on the retina by compensatory eye movements. Previous studies have indicated that basal optic neurons are selective for the direction and velocity of motion. The present study shows that these optokinetic cells also respond to stationary stimuli and thereby could be categorized into three groups. The first group of cells (69.1%) responds to stationary gratings orthogonal to the preferred direction but not to gratings parallel to the preferred direction. They do not respond to stationary random‐dot patterns without any orientational cues. The second group of cells (7.4%) almost equally discharges a series of bursts in response to stationary gratings with any orientations and to random‐dot patterns as well. The third group of cells (23.5%) is responsive to motion but not to stationary gratings and random‐dot patterns. The receptive field of basal optic cells is composed of an excitatory field and an inhibitory field, both of which overlap or occupy different regions in the visual field. The aforementioned properties may be attributed to the excitatory receptive field, whereas the inhibitory receptive field is functional when visual stimuli are moving in the direction opposite to the preferred direction of basal optic cells. The functional significance of visual responses of optokinetic neurons to stationary patterns is discussed. © 2002 Wiley‐Liss, Inc.
High‐density microarray analysis of hippocampal gene expression following experimental brain injury
Authors: Matzilevich David A. , Rall Jason M. , Moore Anthony N. , Grill Raymond J. , Dash Pramod K.
Published: August 2002

Behavioral, biophysical, and pharmacological studies have implicated the hippocampus in the formation and storage of spatial memory. Traumatic brain injury (TBI) often causes spatial memory deficits, which are thought to arise from the death as well as the dysfunction of hippocampal neurons. Cell death and dysfunction are commonly associated with and often caused by altered expression of specific genes. The identification of the genes involved in these processes, as well as those participating in postinjury cellular repair and plasticity, is important for the development of mechanism‐based therapies. To monitor the expression levels of a large number of genes and to identify genes not previously implicated in TBI pathophysiology, a high‐density oligonucleotide array containing 8,800 genes was interrogated. RNA samples were prepared from ipsilateral hippocampi 3 hr and 24 hr following lateral cortical impact injury and compared to samples from sham‐operated controls. Cluster analysis was employed using statistical algorithms to arrange the genes according to similarity in patterns of expression. The study indicates that the genomic response to TBI is complex, affecting approximately 6% (at the time points examined) of the total number of genes examined. The identity of the genes revealed that TBI affects many aspects of cell physiology, including oxidative stress, metabolism, inflammation, structural changes, and cellular signaling. The analysis revealed genes whose expression levels have been reported to be altered in response to injury as well as several genes not previously implicated in TBI pathophysiology. © 2002 Wiley‐Liss, Inc.
Insulin‐like growth factor binding proteins‐1 and ‐2 differentially inhibit rat oligodendrocyte precursor cell survival and differentiation in vitro
Authors: Kühl Nicole M. , De Keyser Jacques , De Vries Hans , Hoekstra Dick
Published: August 2002

Insulin‐like growth factor‐1 (IGF‐1) is a growth and survival factor for oligodendrocyte lineage cells and induces myelination. Its actions are modulated by IGF binding proteins (IGFBPs) that are present in the extracellular fluids or on the cell surface. Additionally, IGFBPs are also known to exert actions that are independent of IGF‐1. We studied whether IGF‐binding proteins (IGFBPs)‐1 and ‐2 modulate rat oligodendrocyte precursor (O2A) cell survival and differentiation in vitro both in the absence and presence of exogenously added IGF‐1. The data reveal that IGFBP‐1 and ‐2 reduced O2A cell survival in the absence and presence of exogenously added IGF‐1. The effects of IGFBP‐1 on cell survival in the presence of exogenously added IGF‐1 were IGF‐1‐dependent, whereas IGFBP‐2 displayed both IGF‐1‐dependent and IGF‐1‐independent effects. Furthermore, IGFBP‐1 and ‐2 inhibited O2A cell differentiation in the presence of IGF‐1 as reflected by decreased expression levels of two myelin proteins, CNPase (2′,3′‐cyclic nucleotide 3′‐phosphohydrolase) and MAG (myelin associated glycoprotein). Analysis of medium samples revealed that O2A cells do not secrete proteases that degrade these IGFBPs. Taken together the data show that IGFBP‐1 and ‐2 are negative effectors of oligodendrocyte survival and differentiation. Accordingly, the role of IGFBPs should be explicitly taken into account when investigating IGF‐1 effects on oligodendrocytes, especially in the context of therapeutic purposes. © 2002 Wiley‐Liss, Inc.
Cerebellar dysfunction is associated with overexpression of proinflammatory cytokine genes in lupus
Authors: Tomita Michiyo , Holman Brita J. , Williams Lee S. , Pang Kevin C.H. , Santoro Thomas J.
Published: August 2002

Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown etiology accompanied by central nervous system involvement in up to 60% of patients. The current study chronicles the expression of cerebellar dysfunction in SLE using MRL‐lpr/lpr mice as the experimental model. These mice spontaneously develop an illness that has immunological and clinical features of human lupus. We found that MRL‐lpr/lpr mice manifest severe and progressive behavioral disturbances indicative of cerebellar dysfunction beginning at 11 weeks of age. Although the lpr gene is known to induce autoimmune features, immunologically normal mice rendered congenic for lpr failed to exhibit disturbances in cerebellar function. Because lupus is a cytokine‐driven disease and overexpression of certain proinflammatory cytokines has been associated with neurodegeneration, the relationship between cerebellar dysfunction and cytokine gene expression was examined. Relative to immunologically normal CBA/J mice, the cerebellum of young (11–15 weeks of age) MRL‐lpr/lpr mice contained high levels of interleukin (IL)‐6 and interferon‐γ (IFNγ) mRNA, which became even more pronounced in old (22–30 weeks of age) autoimmune mice. mRNA levels for the cytokines IL‐1β and IL‐10 were elevated in the cerebellum of old, but not young, MRL‐lpr/lpr mice relative to CBA/J. In contrast, the levels of cerebellar transcripts for IL‐3 and tumor necrosis factor‐α were comparable in autoimmune and normal mice, indicating that enhanced gene expression of IL‐6, IFNγ, IL‐1β, and IL‐10 was selective. These results suggest a potential role for certain proinflammatory cytokines in the pathogenesis of cerebellar disturbances in SLE. J. Neurosci. Res. 64:26–33, 2001. © 2001 Wiley‐Liss, Inc.
Subcellular distribution, calmodulin interaction, and mitochondrial association of the hyaluronan‐binding protein RHAMM in rat brain
Authors: Lynn B.D. , Turley E.A. , Nagy J.I.
Published: August 2002

The CNS contains high levels of the glycosaminoglycan hyaluronan, and neural cells express a variety of proteins that are members of the hyaladherin family of hyaluronan‐binding proteins. We have previously shown that the hyaladherin RHAMM (receptor for hyaluronan‐mediated motility; CD168) is expressed by neural cells in culture; plays a role in astrocyte motility, neurite migration, and axonal growth; and is widely distributed in neurons and oligodendrocytes of developing and adult rat CNS. Here we demonstrate differential localization of various forms of RHAMM in subcellular fractions of adult rat brain. Western blotting indicated the presence of 66, 75, and 85–90 kDa molecular weight RHAMM forms in whole‐brain homogenates. Subfractionation revealed enrichment of the 66 and 85–90 kDa forms in soluble fractions, whereas the 75 kDa form was enriched in mitochondrial fractions. This latter form was retained in osmotically shocked mitochondria, but was liberated by alkali carbonate, suggesting a nonintrinsic mitochondrial membrane association. By double immunohistochemical labeling for RHAMM and the mitochondrial marker cytochrome oxidase, RHAMM was localized to isolated mitochondria in vitro and to neuronal mitochondria in vivo. Hyaluronan‐sepharose chromatography and cetylpiridinium chloride precipitation confirmed the hyaluronan‐binding capacity of RHAMM forms. By calmodulin‐affinity chromatography, endogenously expressed brain RHAMM was demonstrated to bind calmodulin in a Ca2+‐dependent manner. These results, together with reports of RHAMM association with actin and microtubules in other systems, suggest a role of RHAMM in calmodulin‐mediated cell signaling to cytoskeletal elements and/or mitochondria in the CNS and invoke novel functions of its interactions with hyaluronan. J. Neurosci. Res. 65:6–16, 2001. © 2001 Wiley‐Liss, Inc.