bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity of microwave radiances at 85–183 GHz to precipitating ice particles
Authors: Bennartz R. , Bauer P.
Published: July 2003

The response of passive microwave observations to ice particle scattering and surface emissivity has been studied for frequencies at 85, 150, and 183 GHz. Using two‐ and three‐dimensional simulations of different precipitation events, we found that a channel around 150 GHz generally exhibits the strongest scattering signature due to precipitation‐sized ice particles. This channel is only moderately affected by variations in surface emissivity. The sensitivity of the 150 GHz channel to variations in cloud water is about 25 (Kg−1 m3). In comparison, the sensitivity to changes in surface emissivity is about 5 K/(10%) for cold, dry atmospheres and less than 1 K/(10%) for typical midlatitude atmospheres. Channels at around 85 GHz are much stronger affected by variable surface emissivity (sensitivities are up to 15 K/(10%) and show on average a 2 to 2.5 times smaller scattering signature (10 Kg−1 m3). The sensitivity of a water vapor sounding channel at 183–7 GHz to ice particle scattering strongly depends on the environmental conditions but is in general about a factor of 1.5 to 2.5 smaller than at 150 GHz. This is due to the contribution of water vapor in and above the cloud to total emission, masking the scattering signal. The weighting functions of channels at 183–3 and 183–1 GHz peak too high up in the atmosphere and only show a weak or negligible response to the precipitation events under investigation. Based on these results, frequencies around 150 GHz, possibly in combination with channels at 85 and 183–7 GHz seem most appropriate for the detection and retrieval of precipitation properties at middle and high latitudes.
Initial crustal thickness geometry controls on the extension in a back arc domain: Case of the Gulf of Corinth
Authors: Le Pourhiet Laetitia , Burov Evgenii , Moretti Isabelle
Published: July 2003

Since 60 Myr, Peloponnesus and continental Greece have been affected by the Hellenidean compressional and the Aegean extensional phases. This complex evolution resulted in development of a strongly inhomogeneous crust in the Gulf of Corinth region. To study this area, we use a large strain thermomechanical numerical code PARAVOZ previously used for a number of similar problems such as rift evolution. Yet, instead of varying boundary and initial conditions applied to a plane‐layered model, we use available geophysical constraints on the actual deep structure of the lithosphere to test its different possible initial structures. By varying the position of the initial crustal heterogeneity versus the position of the lithospheric slab, we are able to explain the origin of the internal structures and the kinematics of the Gulf of Corinth. The results suggest that the development of shear zones in the lower crust is favored by the gravitational collapse of the thicker part of the crust, whereas the geometry and the kinematics of these shear zones are controlled by the position of the edge of the slab. Asymmetry is seen in cases when a horizontal shift exists between the edge of the slab and the thicker part of the crust. Our model explains the differences between the northern shore and the southern shore as well as the east west variations observed in the Gulf of Corinth.
Implications of changes in seasonal and annual extreme rainfall
Authors: Fowler H. J. , Kilsby C. G.
Published: July 2003

Future projections from climate models and recent observations show a worldwide increase in both the frequency and intensity of heavy rainfall, coinciding with widespread flooding and landslides in Europe. It is estimated, using regional frequency analysis, that the magnitude of extreme rainfall has increased two‐fold over parts of the UK since the 1960s. Intensities previously experienced, on average, every 25 years now occur at 6 year intervals; a consequence of both increased event frequency and changes in seasonality. These climatic changes may be explained by persistent atmospheric circulation anomalies and have huge economic and social implications in terms of increased flooding.
Africa burning: A thematic analysis of the Southern African Regional Science Initiative (SAFARI 2000)
Authors: Swap Robert J. , Annegarn Harold J. , Suttles J. Timothy , King Michael D. , Platnick Steven , Privette Jeffrey L. , Scholes Robert J.
Published: July 2003

The Southern African Regional Science Initiative (SAFARI 2000) was a major surface, airborne, and spaceborne field campaign carried out in southern Africa in 2000 and 2001 that addressed a broad range of phenomena related to land‐atmosphere interactions and the biogeochemical functioning of the southern African system. This paper presents a thematic analysis and integration of the Journal of Geophysical Research SAFARI 2000 Special Issue, presenting key findings of an intensive field campaign over southern Africa in August and September of 2000. The integrating themes deal with surface emissions characterization; airborne characterizations of aerosols and trace gases; regional haze and trace gas characterization; and radiant measurements by surface, aircraft, and remote sensing platforms. Enhanced regional fuel loads associated with the moist La Niña phase of the El Niño‐Southern Oscillation (ENSO) cycle produced above average biomass burning emissions, which consequently dominated all other aerosol and trace gas emissions during the dry season. Southward transport of a broad plume of smoke originating in equatorial Africa and exiting off the east coast toward the Indian Ocean (the river of smoke) is attributed to unusual synoptic airflows associated the ENSO phase. New and revised biogenic and pyrogenic emission factors are reported, including a number of previously unreported oxygenated organic compounds and inorganic compounds from biomass combustion. Emission factors are scaled up to regional emission surfaces for biogenic species utilizing species specific and light‐dependent emission factors. Fire scar estimates reveal contradictory information on the timing of the peak and extent of the biomass‐burning season. Integrated tall stack coordinated measurements (between ground, airborne and remotely sensing platforms) of upwelling and downwelling radiation in massive thick aerosol layers covering much of southern Africa yield consistent estimates of large negative forcing for both surface and top of atmosphere radiative forcing. Radiation calculations are supported by novel information on chemical speciation and internal aerosol particle structure. The overall conclusion is that SAFARI 2000, as an integrating theme, has been able to give significant new insights into the regional scale biogeochemical cycling of southern Africa and contributed in important ways to the validation of remote sensing instruments on board the NASA Terra spacecraft.
Late Pleistocene and Holocene groundwater recharge from the chloride mass balance method and chlorine‐36 data
Authors: Zhu Chen , Winterle James R. , Love Erica I.
Published: July 2003

The chloride mass balance (CMB) method for estimating groundwater recharge is economic and effective, provided that the hydrological conditions for its applications are met and the modeling parameters are known. However, modeling parameters such as precipitation and Cl− deposition rates vary temporally, most notably as a result of the climatic changes from late Pleistocene to Holocene. The temporal variability of atmospheric Cl− input and annual precipitation were considered in this study by using a discrete steady state CMB model with different parameters for late Pleistocene and Holocene. Cl− deposition rates, estimated from 36Cl data, were lower in late Pleistocene than Holocene at Yucca Mountain, Nevada, but higher in late Pleistocene than Holocene at Black Mesa, Arizona. Paleoclimate proxies at both Yucca Mountain and Black Mesa point to higher precipitation rates in late Pleistocene than Holocene. The resulting average recharge estimates for Black Mesa are 9 ± 5 mm/yr for Holocene and 35 ± 22 mm/yr for late Pleistocene. Local recharge rates at Yucca Mountain were estimated from the 36Cl/Cl ratios and Cl− concentrations in perched waters. The estimated recharge for Yucca Mountain is 5 ± 1 mm/yr for Holocene and 15 ± 5 mm/yr for late Pleistocene. These recharge rates are comparable to results of independent numerical groundwater flow models and watershed‐scale infiltration models at Black Mesa and Yucca Mountain, respectively.
Isolation and characterization of a gene for a repetitive proline rich protein (OsPRP) down‐regulated during submergence in rice (Oryza sativa)
Authors: Akiyama Takashi , Pillai M. Arumugam
Published: July 2003

Differential screening was performed on a cDNA library made from RNAs isolated from rice seedlings (variety Yukihikari) grown in submergence condition. A cDNA clone (OsPRP) encoding a repetitive proline‐rich protein of 358 amino acids and molecular weight of 39 kDa was obtained. The C‐terminal region of OsPRP contains proline (P) residues (40%), and high levels of glutamic acid (E) and lysine (K). The N‐terminus was free from proline residues. Sequence analysis indicated that 40 distinct PEPK repetitive sequence motifs were present in the sequence along with other repetitive motifs. Furthermore, four phosphorylation sites were predicted from the sequence. The domain structure of OsPRP was compared with proline‐rich proteins from other monocot species. The N‐terminus of OsPRP is highly hydrophobic indicating the presence of a signal peptide. Southern blot data indicate that in the Yukihikari genome OsPRP is most likely encoded by a single gene. The expression of OsPRP was relatively uniform in the young seedlings. However, tissue‐specific expression of OsPRP indicated that shoot tissue accumulates more mRNA, and the root has relatively low expression. In addition, OsPRP expression is regulated by various environmental factors and is down‐regulated under submergence stress. Exogenous application of growth hormones, namely abscisic acid (ABA), methyl jasmonate (MeJ) and ethephon caused significant repression of the OsPRP transcript.

The nucleotide sequence reported in this paper has been reported to the NCBI, GenBank under accession number AF 337054.
Comparative characterization of the two primary pumps, H+‐ATPase and Na+‐ATPase, in the plasma membrane of the marine alga Tetraselmis viridis
Authors: Pagis Lyudmila Y. , Popova Larissa G. , Andreev Igor M. , Balnokin Yurii V.
Published: July 2003

The transport characteristics of the plasma membrane H+‐ATPase (PMHA) and Na+‐ATPase (PMNA) from marine unicellular green alga Tetraselmis viridis Rouch. were studied using sealed plasma membrane vesicles isolated from this species. The activities of the ATPases were investigated by monitoring the ATP‐dependent pH changes in the vesicle lumen. PMHA operation led to acidification of the vesicle lumen, whereas Na+ translocation into plasma membrane vesicles catalysed by PMNA was accompanied by H+ efflux, namely the alkalization of the vesicle lumen (Balnokin et al., FEBS Lett 462: 402–406, 1999). The intravesicular acidification and alkalization were detected with the ΔpH probe acridine orange and the pH probe pyranine, respectively. PMHA and PMNA were found to operate in distinct pH regions, maximal activity of PMHA being observed at pH 6.5 and that of PMNA at pH 7.8. Kinetic studies revealed that the ATPases have similar affinities to their primary substrate, MgATP complex (an apparent Km = 34 ± 6.2 µM for PMHA and 73 ± 8.7 µM for PMNA). At the same time, the ATPases were differently affected by free Mg2+ and ATP. Free Mg2+ appeared to be a mixed‐type inhibitor for PMNA (Ki′ = 210 µM) but it did not suppress PMHA. Conversely, free ATP markedly suppressed PMHA being a mixed‐type inhibitor (Ki′ = 330 µM), but PMNA was affected by free ATP only slightly. Furthermore, the ATPases substantially differed in their sensitivities to the inhibitors of membrane ATPases, such as orthovanadate, N‐ethylmaleimide and N,N′‐dicyclohexylcarbodiimide. The differences found in the properties of the PMHA and PMNA are discussed in terms of regulation of their activities and their capacity to be involved in cytosolic ion homeostasis in T. viridis cells.
Photoinhibition and the xanthophyll cycle are not enhanced in the salt‐acclimated halophyte Artimisia anethifolia
Authors: Lu Congming , Qiu Nianwei , Lu Qingtao
Published: July 2003

The effects of high salinity (up to 400 mM NaCl) on photosystem II (PSII) photochemistry, photoinhibition and the xanthophyll cycle were investigated in the halophyte Artimisia anethifolia grown under outdoor conditions. In order to examine the changes in PSII photochemistry, photoinhibition, thermal dissipation associated with the xanthophyll cycle in salt‐acclimated plants, the experiments were conducted at midday on a clear day (maximal irradiance 1500 μmol m−1 s−1) and on a cloudy day (maximal irradiance 700 μmol m−1 s−1), respectively. With increasing salt concentration, the accumulation of sodium and chloride in leaves increased considerably while the relative growth rate and CO2 assimilation rate decreased significantly. Salinity induced no effects on PSII photochemistry, thermal energy dissipation, and the contents of the xanthophyll cycle pigments either on a clear day or on a cloudy day. However, when compared with those on a cloudy day, PSII photochemistry decreased and thermal energy dissipation increased significantly in both control and salt‐acclimated plants on a clear day. The levels of zeaxanthin and antheraxanthin at the expense of violaxanthin were higher on a clear day than on a cloudy day. The results suggest that photoinhibition and the xanthophyll cycle were not induced by high salinity but by high light only in A. anethifolia plants. The results also suggest that A. anethifolia showed high resistance not only to high salinity, but also to photoinhibition even when it was treated with high salinity and exposed to full sunlight.
Differential gene expression analysis of strawberry cultivars that differ in fruit‐firmness
Authors: Salentijn Elma M. J. , Aharoni Asaph , Schaart Jan G. , Boone Marjan J. , Krens Frans A.
Published: July 2003

Firmness is an important selection criterium in the breeding of fruit, including strawberry (Fragaria × ananassa Duch.). Clear differences in fruit‐firmness are observed between cultivars. In order to identify candidate genes which might be associated with such textural differences, gene expression levels were compared for a soft and a firm cultivar (cv. Gorella and cv. Holiday, respectively). DNA‐microarrays representing 1701 strawberry cDNAs were used for simultaneous hybridization of two RNA populations derived from red ripe fruit of both cultivars. In total 61 clones (3.6% of the total cDNAs on the arrays) displayed differential expression, including 10 clones (8 different ones) which showed homology to cell wall related genes in the public databases. The results from the microarray experiments were further confirmed by RNA gel blots, which were also used to examine gene expression in a third cultivar, Elsanta, showing an intermediate texture phenotype (offspring of a cross between Gorella and Holiday). Interestingly, two genes encoding proteins catalysing successive reactions in lignin metabolism (cinnamoyl CoA reductase and cinnamyl alcohol dehydrogenase) showed the highest difference in expression level.
Uptake and metabolism of N6‐benzyladenine and 1‐naphthaleneacetic acid and dynamics of indole‐3‐acetic acid and cytokinins in two callus lines of Actinidia deliciosa differing in growth and shoot organogenesis
Authors: Centeno María L. , Rodríguez Ana , Feito Isabel , Sánchez‐Tamés Ricardo , Fernández Belén
Published: July 2003

Uptake, metabolism and accumulation of N6‐benzyladenine (BA) and 1‐naphthaleneacetic acid (NAA) as well as changes in endogenous indole‐3‐acetic acid (IAA) and several isoprenoid‐type cytokinins (Cks) were characterized in two callus lines of Actinidia deliciosa cv. Hayward showing different growth and shoot organogenic responses to exogenously applied 2.7 µM NAA and 4.4 µM BA. Studies were carried out in callus 0, 1, 12, 24 and 48 h after the onset of their fifth subculture on a medium containing [3H]NAA or 8‐[14C]BA. Kiwifruit callus of line A presented high caulogenic response and lower growth that was positively associated with faster BA uptake, with transient accumulation of BA and isoprenoid‐type Cks, mainly zeatin, exceeding three‐ and four‐fold that of the non‐caulogenic callus, and with values of the BA/NAA ratio exceeding 1, in fact higher than the BA/NAA ratio in the culture medium. The accumulation of BA took place in both callus lines during the first 24 h of subculture and before the re‐initiating of callus proliferation. The higher growth and the low or null caulogenic response shown by line B callus were correlated with faster NAA uptake, with endogenous NAA levels two‐fold higher than in A calli, with higher IAA amounts and with values of the BA/NAA ratio below 1. Moreover, at 48 h free NAA in both kinds of callus reached levels close to those found after 35 days of subculture. Results suggest that temporal accumulation of BA and endogenous Cks is involved in the initiation of cell division leading to callus growth, whereas the maintenance of high NAA and IAA levels are related to the support of long‐term callus development. It also appears that for callus cells to become committed to shoot organogenesis, they must have a concentration of active Cks higher than a threshold value during the first 2 days of culture on fresh medium, while at the same time the concentration of auxins must not exceed a certain maximum.
Temperature modulates the cell wall mechanical properties of rice coleoptiles by altering the molecular mass of hemicellulosic polysaccharides
Authors: Nakamura Yukiko , Wakabayashi Kazuyuki , Hoson Takayuki
Published: July 2003

The present study was conducted to investigate the mechanism inducing the difference in the cell wall extensibility of rice (Oryza sativa L. cv. Koshihikari) coleoptiles grown under various temperature (10–50°C) conditions. The growth rate and the cell wall extensibility of rice coleoptiles exhibited the maximum value at 30–40°C, and became smaller as the growth temperature rose or dropped from this temperature range. The amounts of cell wall polysaccharides per unit length of coleoptile increased in coleoptiles grown at 40°C, but not at other temperature conditions. On the other hand, the molecular size of hemicellulosic polysaccharides was small at temperatures where the cell wall extensibility was high (30–40°C). The autolytic activities of cell walls obtained from coleoptiles grown at 30 and 40°C were substantially higher than those grown at 10, 20 and 50°C. Furthermore, the activities of (1→3),(1→4)‐β‐glucanases extracted from coleoptile cell walls showed a similar tendency. When oat (1→3),(1→4)‐β‐glucans with high molecular mass were incubated with the cell wall enzyme preparations from coleoptiles grown at various temperature conditions, the extensive molecular mass downshifts were brought about only by the cell wall enzymes obtained from coleoptiles grown at 30–40°C. There were close correlations between the cell wall extensibility and the molecular mass of hemicellulosic polysaccharides or the activity of β‐glucanases. These results suggest that the environmental temperature regulates the cell wall extensibility of rice coleoptiles by modifying mainly the molecular mass of hemicellulosic polysaccharides. Modulation of the activity of β‐glucanases under various temperature conditions may be involved in the alteration of the molecular size of hemicellulosic polysaccharides.
Antioxidant enzyme activities in shoots from three mycorrhizal shrub species afforested in a degraded semi‐arid soil
Authors: Alguacil M. M. , Hernández J. A. , Caravaca F. , Portillo B. , Roldán A.
Published: July 2003

Mycorrhizae may help plants to thrive in Mediterranean semi‐arid ecosystems by altering antioxidant enzyme activities. Our objective was to determine the influence of mycorrhizal inoculation with an allochthonous arbuscular mycorrhizal (AM) fungus, Glomus claroideum, Schenck & Smith, or with a mixture of native AM fungi, on the activity of antioxidant enzymes from shoots of Olea europaea L. ssp. sylvestris, Retama sphaerocarpa (L.) Boissier and Rhamnus lycioides L. seedlings afforested in a degraded Mediterranean semi‐arid soil. One year after planting, shoot biomass of inoculated O. europaea seedlings was about 630%, of non‐inoculated plants. Shoot biomass of G. claroideum‐colonized R. sphaerocarpa was greater than that of seedlings inoculated with the mixed native AM fungi after 12 months. Inoculation with a mix of native AM fungi was the most effective treatment for increasing shoot biomass and N, P and K contents in shoot tissues of R. lycioides. Both mycorrhizal inoculation treatments increased the nutrient contents in shoots of O. europaea and R. lycioides. In O. europaea plants, the inoculation treatments increased catalase, ascorbate peroxidase and dehydroascorbate reductase activities, but not monodehydroascorbate reductase and glutathione reductase activities. Inoculation with G. claroideum increased the activities of all antioxidant enzymes in R. sphaerocarpa. Monodehydroascorbate reductase, glutathione reductase and superoxide dismutase activities in R. lycioides leaves were preferentially increased by inoculation with the mixture of native AM fungi. This work support the view that increased antioxidant enzyme activities could be involved, at least in part, in the beneficial effects of mycorrhizal colonization on the performance of shrub species grown under semi‐arid Mediterranean conditions.
Bone augmentation using rhGDF‐5–collagen composite
Authors: Kuniyasu Hiroya , Hirose Yukito , Ochi Morio , Yajima Akihiro , Sakaguchi Kunihiko , Murata Masaru , Pohl Jens
Published: July 2003

Abstract: The aim of this study was to evaluate the effectiveness of local application of growth differentiation factor‐5 (GDF‐5)‐collagen composite on bone augmentation on the rat calvaria. GDF‐5–collagen composite is made from recombinant human GDF‐5 (rhGDF‐5) and purified bovine type I atelocollagen. The GDF‐5 solution was mixed with 0.3% atelocollagen acid solution, and the mixture was lyophilized. The spongy lyophilized material was pressed into the shape of a minidisk to make the GDF‐5–collagen composite. The GDF‐5–collagen composite contained 1, 10, or 100‐μg rhGDF‐5. The control collagen composite contained 0‐μg rhGDF‐5. The GDF‐5–collagen composite or control collagen composite was inserted beneath the calvarial periosteum of 4‐week‐old rats. At 3 weeks after implantation, the implants containing 1‐μg rhGDF‐5 had mostly induced new bone formation on the cranial side. In the implants containing 10‐ μg rhGDF‐5, bone formation had proceeded to the center of the GDF‐5–collagen composite from the periosteal and the cranial sides, and bone marrow was seen focally. The augmented bone showed a connected trabecular structure with abundant vascularization. The implants containing 100‐μg rhGDF‐5 were nearly entirely replaced by new bone with bone marrow, and the augmented bone was firmly connected with the original bone. Neither cartilage nor bone formation was found in the control collagen composite. Thus, we conclude that the GDF‐5–collagen composite may be a superior biomaterial for bone augmentation and this composite could be useful as a local osteoinductive device.
Early detection of implant healing process using resonance frequency analysis
Authors: Huang Haw‐Ming , Chiu Ching‐Lai , Yeh Ching‐Ying , Lin Che‐Tong , Lin Li‐Hsiang , Lee Sheng‐Yang
Published: July 2003

In this study,in vitroandin vivomodels were adopted for assessing the application of resonance frequency analysis (RFA) in the early detection of implant stability. In thein vitrotests, RF values of implants placed in bone block with predrilled cavities of 3.75 and 5.0 mm were measured and compared. Stone was used to fill the inter‐space between implants and the bone blocks. Our results showed that poor initial stability conditions contributed to a lower initial RF (IRF) value (5.41±0.32 kHz) and a longersimulatedhealing period (41 min) than that of well‐fitted conditions (9.63±0.34 kHz for IRF, 14 min for thesimulatedhealing period,P<0.05). To validate suchin vitrotests, animal models were also performed. Implants were placed in the left tibias of six rabbits using a general surgery procedure. The modal testing method was used to test the RF values of the implants. The RF values of the implants increased significantly (P<0.05) during the healing period and reached a plateau when the implant–bone interface was united. The variations of RF values of the testing implants showed a similar trend to the results ofin vitrotests, i.e., implants with higher initial RF values had shortersimulatedhealing times. Based on these findings, we concluded that RFA is a reliable and accurate method for early assessment of the osseointegration process.
Effects of occlusiveness of a titanium cap on bone generation beyond the skeletal envelope in the rabbit calvarium
Authors: Yamada Yutaka , Nanba Koichi , Ito Koichi
Published: July 2003

Abstract: We evaluate the effects of occlusiveness of a titanium cap on bone generation beyond the skeletal envelope. In eight rabbits, the calvarial bone was exposed and a circular groove was prepared with a trephine drill. After marrow penetration, a standardized hemispherical titanium cap, either with or without small holes (1.5 mm in diameter), was then placed into the bone and covered by a cutaneous flap. After 1 month or 3 months of healing, the animals were euthanized and examined histologically. The percentage area of newly generated tissue consisting of mineralized bone and marrow spaces in each section was calculated relative to the area bounded by the hemispherical shape of the titanium cap and the parent bone; this latter volume was taken to be 100%. Furthermore, the cross‐sectional areas of generated mineralized bone expressed as percentages of the total tissue area generated within each space were determined. In the 1‐month specimens, there was no statistically significant difference between the two caps in the amount of tissue generated, 54.7%±12.2% with holes vs. 60.4%±8.8% without holes (p=0.225). However, in the 3‐month specimens, we observed a significant difference between the caps (55.9%±7.4% with holes vs. 89.9%±6.5% without holes, P<0.05). Also, there was a statistically significant difference between 1‐ and 3‐month specimens in the amount of tissue generated under the cap without holes (60.4%±8.8% vs. 89.9%±6.5%, P<0.05). Although there was no significant difference in the relative amount of mineralized bone generated between the caps with holes and those without holes in the 1‐month specimens (27.7%±4.8% vs. 30.8%±6.4%, P=0.225), there was a statistically significant difference between the two caps in the 3‐month specimens (24.3%±4.1% with holes vs. 34.0%±8.6% without holes, P<0.05). A substantial ingrowth of fibrous connective tissue through the holes appeared to prevent further new tissue generation in a defined area adjacent to the bone surface. We concluded that total occlusiveness, sufficient stiffness of the cap, as well as the passage of time will allow predictable mineralized bone augmentation to occur in spaces beyond the skeletal envelope.
Hard tissue reaction to dual acid‐etched titanium implants: influence of plaque accumulation. A histological study in humans
Authors: Kohal Ralf J. , Bächle Maria , Emmerich Dominik , Beschnidt Sven M. , Strub Jörg R.
Published: July 2003

Abstract: Objectives: The aim of this investigation was to evaluate histologically, histometrically, and histomorphometrically the influence of plaque accumulation on the peri‐implant hard tissues.

Material and methods: Twelve fully edentulous subjects were selected for this investigation. Four to five standard titanium screw implants were placed interforaminally. Two small custom‐made screw implants were incorporated in the region of the former first molar, one in each lower quadrant. One month after abutment connection, plaque control was terminated randomly at one of the custom‐made implants and continued at the other implant. The custom‐made implants and the surrounding tissue were harvested after different time points of plaque accumulation (7, 21, or 90 days). Thus, according to the plaque control program and implant removal time, there were six groups each with four implants for investigation. After histologic processing of the biopsies, histologic, histometric, and histomorphometric analyses were performed.

Results: Four of the 24 implants were unavailable for analysis. One implant was mobile at abutment connection and another implant was mobile 2 weeks after abutment connection; both implants had to be removed. The bone around two implants was destroyed during the removal with the trephine bur; therefore, these two implants could not be evaluated histologically either. No differences in the histologic appearance of the peri‐implant bone between the different groups could be observed. Histomorphometrically, the implant surface in contact with mineralized bone as a fraction of the implant surface (measured from the buccal to the lingual implant shoulder) varied between 59% and 73%. The implant surface in contact with mineralized bone from the first bone‐to‐implant contact buccally to the first bone‐to‐implant contact lingually varied between 80.6% and 91.5%. The values for the distance from the implant shoulder to the first bone‐to‐implant contact, i.e. peri‐implant bone loss, varied from 1.1 to 2.2 mm. No statistically significant differences could be found between any of the evaluated variables.

Conclusions: This clinical investigation is the first to evaluate the hard tissue reactions to different plaque accumulation periods. Within the limits of this experiment, it can be concluded that the bone reaction toward the different plaque accumulation periods and in the different plaque control/accumulation groups were similar. It can be further concluded that the observed bone loss is rather attributed to the establishment of the biologic width than to plaque accumulation.
Sinus grafting with autogenous platelet‐rich plasma and bovine hydroxyapatite
Authors: Fürst Gabor , Gruber Reinhard , Tangl Stefan , Zechner Werner , Haas Robert , Mailath Georg , Sanroman Fidel , Watzek Georg
Published: July 2003

Abstract: In this study, bovine hydroxyapatite (HA) alone or in combination with activated platelet‐rich plasma (PRP) was examined for its usefulness for single‐stage sinus grafting in minipigs. In 12 adult minipigs, Schneider's membrane of 24 sinuses was elevated bilaterally through an extra‐oral approach. The material was divided into two groups of 12 sinuses. In one of these groups, the space between Schneider's membrane and the sinus wall was grafted with activated autogenous PRP and HA (PRP side). In the other, HA alone was used for grafting (control side). At the same time two dental implants with a machined surface were inserted into the grafting material through the facial sinus wall. Four animals of each group were sacrificed at 3, 6 and 12 weeks, and undecalcified thin‐cut and ground sections (Donath 1988) stained with toluidine blue were prepared. In the facial sinus wall, fewer bone‐to‐implant contacts were present on the PRP side at 3 and 6 weeks than on the control side. At 12 weeks, the PRP side had caught up with the control side. In grafted bone, contacts on the PRP side were more extensive than on the control side at 3 weeks, had dropped below control side levels at 6 weeks and surpassed these at 12 weeks. This study showed that PRP has a differential effect on osseointegration in grafted bone and local host bone. Combined with HA it was not demonstrably superior to HA alone.
Effect of calcium phosphate coating composition and crystallinity on the response of osteogenic cells in vitro
Authors: Ter Brugge Petra J. , Wolke Joop G.C. , Jansen John A.
Published: July 2003

Abstract: The aim of this study was to investigate the effect of calcium phosphate coating crystallinity and composition on the proliferation and differentiation of rat bone marrow (RBM) cells. Grit‐blasted titanium substrates were provided with thin sputter‐coated calcium phosphate (Ca‐P) films of different composition. The Ca‐P‐coated substrates were used as‐sputtered or were heat‐treated. XRD measurements showed that the as‐sputtered coatings had an amorphous structure, whereas the heat‐treated substrates showed an amorphous–crystalline structure. RBM cells were cultured on these substrates and on noncoated titanium substrates. After specific culture times, the expression of osteogenic markers by the cells was studied. On the amorphous–crystalline coatings as well as on titanium substrates, RBM cells proliferated, expressed alkaline phosphatase and showed mineralization. More mineralization was found on the amorphous–crystalline coatings than on the titanium substrates. Some precipitation was also found on substrates that were incubated in complete culture medium without cells. This precipitate disappeared after prolonged incubation. Alkaline phosphatase expression differed on the various amorphous–crystalline Ca‐P‐coated substrates, but no difference was found in the mineralization on these substrates. The amorphous Ca‐P coatings showed extensive dissolution and some signs of precipitation after longer culture periods. Proliferation and differentiation of RBM cells was not seen on the amorphous coatings, regardless of Ca‐P composition. We conclude that amorphous–crystalline Ca‐P coatings stimulate differentiation of RBM cells, with only limited differences between coatings of various composition. In contrast, Ca‐P coatings with an amorphous structure inhibit the growth and differentiation of RBM cells. This effect was found on all amorphous substrates, regardless of Ca‐P composition.
Peri‐implant bone alterations in relation to inter‐unit distances
Authors: Cardaropoli Giuseppe , Wennström Jan L. , Lekholm Ulf
Published: July 2003

Abstract: The aim of the present retrospective study was to evaluate longitudinal alterations in radiographic bone topography at proximal sites of three‐unit implant‐supported fixed partial prostheses during the first 3 years after bridge installation, in relation to vertical and horizontal inter‐unit distances. The subjects were partially dentate patients who had received implant‐supported fixed partial prostheses during the year 1995 at the Brånemark Clinic, Göteborg, Sweden. For inclusion in the study, the patient had to have a three‐unit bridge construction supported by three implants in the posterior area of the jaw. Twenty‐eight patients having 35 screw‐retained prostheses on Brånemark standard implants fulfilled the inclusion criteria. Radiographs obtained at bridge installation and at 1‐ and 3‐year follow‐ups were assessed for implant positions, contact point level, bone level at implants and adjacent tooth and mid‐proximal bone crest level. The data were analysed with respect to two proximal units: tooth/implant units (n=35) and implant/implant units (n=70). Multiple regression analyses were used to evaluate the influence of various factors on the peri‐implant and periodontal bone level changes during the 3 years of follow‐up. At the tooth/implant units, the mean bone loss over the 3 years was 0.5 mm at the implant and 0.4 mm at the tooth. Multiple regression analysis failed to identify significant explanatory factors for the peri‐implant/periodontal bone level changes at the tooth/implant units (R2=0.28). At the implant/implant units, the peri‐implant bone loss was 0.6–0.7 mm and was significantly influenced by the vertical inter‐implant distance (P<0.01), the difference in bone level at baseline between two neighbouring implants (P<0.001) and the bone level changes at the opposed implant surface (P<0.001) (R2=0.49). Furthermore, the magnitude of apical displacement of the inter‐implant bone crest level during the 3 years of follow‐up was negatively associated with the horizontal inter‐implant distance (P<0.05). The results of the study demonstrated that both vertical and horizontal differences in implant positions might influence bone alterations in the inter‐implant area during the first 3 years of loading, while the data failed to show corresponding relationships for the bone changes at the proximal area between the implant and the neighbouring tooth.
Osseointegration on implant surfaces previously contaminated with plaque
Authors: Kolonidis Stavros G. , Renvert Stefan , Hämmerle Christopher H.F. , Lang Niklaus P , Harris David , Claffey Noel
Published: July 2003

Abstract: This study investigated whether osseointegration can occur on a surface which had previously been coated with dental plaque. The mandibular premolar regions of four young adult Labrador dogs were used for the study. The lower premolars (P1, P2, P3, and P4) were extracted on either side of the mandibles. Following a 12‐week healing period, three 3.75 mm×13 mm commercially pure titanium implants (Nobel Biocare®AB, Gothenburg, Sweden) were partially inserted in one side of each mandible. This resulted in some threads protruding from the tissues into the oral cavity. Plaque was allowed to accumulate on the exposed implant surfaces. Following a 5‐week healing period, the contaminated parts of each implant were treated using three different cleaning techniques: (1) swabbing with supersaturated citric acid for 30 s on a cotton pellet followed by rinsing with physiological saline, (2) cleansing with a toothbrush and physiological saline only for 1 min, and (3) swabbing with 10% hydrogen peroxide (H2O2) on a cotton pellet for 1 min followed by rinsing with physiological saline. The treated implants and one previously unused implant (control) were then placed into freshly prepared tapped sites to the full implant length on the contralateral sides of the mandibles. Following 11 weeks of healing, biopsies were obtained and ground sections prepared for histomorphometric analysis. All treatment modalities were associated with direct bone to implant contact on the portion of implant surface previously exposed to the oral environment. In conclusion, The results demonstrate that osseointegration can occur to surfaces that were plaque contaminated and cleaned by different methods.
Investigation of allogeneic mesenchyrnal stem cell‐based alveolar bone formation: preliminary findings
Authors: De Kok Ingeborg J. , Peter Susan J. , Archambault Michael , Van Den Bos Christian , Kadiyala Sudha , Aukhil Lkramuddin , Cooper Lyndon F.
Published: July 2003

Abstract: This study was designed to evaluate mesenchymal stem cell (MSC)‐based alveolar bone regeneration in a canine alveolar saddle defect model. MSCs were loaded onto hydroxyapatite/tricalcium phosphate (HA/TCP) matrices. Scanning electron microscopic (SEM) evaluation demonstrated greater than 75% MSC coverage of the HA/TCP porous surface prior to placement regardless of MSC donor. Matrices, 6 mm×6 mm×20 mm, with and without cells, were implanted for 4 and 9 weeks, then removed for histological evaluation of bone formation. Cell‐free control matrices were compared with MSC‐loaded matrices post implantation. Histomorphometrical analysis showed that equivalent amounts of new bone were formed within the pores of the matrices loaded with autologous MSCs or MSCs from an unrelated donor. Bone formation in the cell‐free HA/TCP matrices was less extensive. There was no histologic evidence of an immunological response to autologous MSCs. Surprisingly, allogeneic MSC implantation also failed to provoke an immune response. Analysis of circulating antibody levels against MSCs supported the hypothesis that neither autologous nor allogeneic MSCs induced a systemic response by the host. Analysis of dye‐labelled MSCs in histological sections confirmed that the MSCs persisted in the implants throughout the course of the experiment. At 9 weeks, labelled cells were present within the lacunae of newly formed bone. We conclude that autologous and allogeneic MSCs have the capacity to regenerate bone within craniofacial defects.
Autogenous bone graft and ePTFE membrane in the treatment of peri‐implantitis. II. Stereologic and histologic observations in cynomolgus monkeys
Authors: Schou Søren , Holmstrup Palle , Skovgaard Lene Theil , Stoltze Kaj , Hjørting‐Hansen Erik , Gundersen Hans Jørgen G.
Published: July 2003

Abstract: The purpose of the present study was to evaluate the effect of autogenous bone graft particles and expanded polytetrafluoroethylene (ePTFE) membrane in the treatment of peri‐implantitis with stereologic and histologic methods. Clinical and radiographic findings are reported elsewhere. Experimental peri‐implantitis with a bone loss of 4–6 mm was established during 14–22 months around 64 implants with a titanium plasma‐sprayed (TPS) surface in eight cynomolgus monkeys (Macaca fascicularis). The defects were treated with autogenous bone+membrane (B+M), autogenous bone (B), membrane (M), or a conventional flap procedure (control) (C). The animals were killed 6 months after surgery. Healthy peri‐implant tissue was established irrespective of the applied treatment procedure. However, the amount of bone (autogenous bone graft particles and regenerated bone) and re‐osseointegration were significantly higher in defects treated with B+M as compared with the three other treatment modalities. A mean bone‐to‐implant contact of 45% was estimated within defects treated with B+M. The corresponding values for the B, M, and C groups were 22, 21, and 14%. The present study therefore demonstrates that autogenous bone graft particles covered by an ePTFE membrane is a useful surgical treatment procedure of experimental peri‐implantitis around implants with a TPS surface in cynomolgus monkeys. Obviously, there is a background for long‐term evaluation in humans.
Primary treatment with autologous stem cell transplantation in mantle cell lymphoma: outcome related to remission pretransplant
Authors: Andersen Niels S. , Pedersen Lone , Elonen Erkki , Johnson Anna , Kolstad Arne , Franssila Kaarle , Langholm Ruth , Ralfkiær Elisabeth , Åkerman Måns , Eriksson Mikael , Kuittinen Outi , Geisler Christian H. ,   for the Nordic Lymphoma Group
Published: July 2003

Objectives: The aim of the first Nordic mantle cell lymphoma (MCL) protocol was to study the clinical significance of an augmented CHOP induction chemotherapy followed by high‐dose chemotherapy and autologous stem cell transplantation (ASCT) and to examine the prognostic significance of stem cell contamination rates in newly diagnosed patients with MCL.

Patients and methods: Forty‐one newly diagnosed patients below 66 yr were enrolled and given three series of an augmented CHOP regimen. Responders underwent stem cell mobilization with a fourth course of CHOP, stem cell harvest and ASCT. Stem cell purging was optional in the protocol and followed the routine of each participating centre. The number of tumour cells in the reinfused autografts was estimated by flow cytometry or quantitative PCR.

Results: Induction therapy led to complete remission (CR) in 11 of 41 patients (27%), partial remission (PR) in 20 of 41 patients (49%) and no response in nine patients (22%), whereas one patient was not evaluable. Twenty‐seven of the 31 responders underwent ASCT and 24 achieved or maintained a CR. The overall and failure‐free 4‐yr survival on intention‐to‐treat basis were 51% and 15%, respectively. Among the transplanted patients, a significantly increased failure‐free (P < 0.03) and overall survival (P = 0.03) was noted among patients transplanted in CR compared with PR, respectively. By contrast, reinfusion of highly variable numbers of tumour cells with the autografts (range 0.71–80 × 106 tumour cells), did not affect outcome.

Conclusion: In MCL, an important strategy to improve the outcome will be to intensify the induction chemotherapy.
Gelatinases (MMP‐2 and MMP‐9), TIMP‐1 expression and the extent of neovascularization in aggressive non‐Hodgkin's lymphomas
Authors: Kuittinen Outi , Apaja‐Sarkkinen Meeri , Turpeenniemi‐Hujanen Taina
Published: July 2003

Objectives:  The present study was carried out to clarify the role of matrix metalloproteinase‐2 and ‐9 (MMP‐2 and MMP‐9), tissue inhibitor of metalloproteinase‐1 (TIMP‐1) and the extent of neovascularization in the clinicopathologic behavior of non‐Hodgkin's lymphomas.

Methods:  Paraffin‐embedded histologic sections from 57 patients with aggressive non‐Hodgkin's lymphomas were stained with MMP‐2, MMP‐9, TIMP‐1, and factor VIII antibodies to correlate the expression of these markers to the clinical disease characteristics.

Results:  Strong MMP‐9 staining was found to be an adverse prognostic factor among patients with aggressive B‐cell lymphomas, the probabilities for 5‐yr disease‐free survival being 73%, 63%, 50%, and 0% in patients with grades 0, 1, 2, and 3 staining, respectively. Among the patients with strong (grades 2 and 3) MMP‐9 staining, however, positivity for TIMP‐1 indicated a trend toward a more favorable prognosis. TIMP‐1 expression also correlated with the immunoblastic and anaplastic lymphoma subtypes. The expression of the proteins for MMP‐2 and factor VIII had no independent prognostic role. None of the study parameters correlated with disease stage, the occurrence of extranodal infiltrates, the occurrence of bulky tumor, or the IPI scores.

Conclusions:  Positivity for MMP‐9 immunoreactive protein is an independent sign of an unfavorable prognosis in non‐Hodgkin's lymphomas. This is not mediated through influences in tumor dissemination or neovascularization indicating it to carry other important biological functions.
Danaparoid for heparin‐induced thrombocytopenia: an analysis of treatment failures
Authors: Kodityal Sandeep , Manhas Amit H , Udden Mark , Rice Lawrence
Published: July 2003

Background: Patients with heparin‐induced thrombocytopenia (HIT) (with or without thrombosis) require alternative anticoagulation because of their extreme risk of new thromboembolic complications. The first effective agent for this purpose may be danaparoid, a less‐sulfated low molecular weight heparinoid. Recently, direct thrombin inhibitors have been used.

Objective: Five HIT patients, who developed new thromboembolic complications while receiving danaparoid, were analyzed to consider possible reasons for treatment failure and to promulgate strategies that improve efficacy.

Results: Three patients had acute HIT, one had recent HIT, and one with remote HIT was re‐exposed to heparin during heart surgery. Danaparoid was started as intravenous bolus and infusion in one patient, and as 1250 units subcutaneously twice daily in four patients. The new complications that emerged on danaparoid were new venous thrombi in three patients (one with pulmonary emboli), lower extremity arterial thrombosis in one, myocardial ischemia in one, thromboembolic cardiovascular accidents in one, and fatal bowel necrosis in one (two patients suffered more than one complication). Platelet counts did not improve or worsened in four, improved partially in the other, and parameters of disseminated intravascular coagulation failed to improve in one patient. Four patients responded relatively dramaticaly when direct thrombin inhibitors were substituted. Possible reasons for danaparoid failure include that: 1) no treatment is expected to completely prevent complications, 2) antithrombin III consumption can blunt efficacy in some patients, 3) low or intermediate doses may be insufficient, and 4) there was clinically significant cross‐reactivity of the pathogenic HIT antibodies.

Conclusions: It is emphasized that the possibility of clinically significant antibody cross‐reactivity and that low or intermediate dosage may be inadequate when using danaparoid in therapy of HIT. The latter problem probably extrapolates to other anticoagulants used for HIT.