The pH and titratable acidity of a range of diluting drinks and their potential effect on dental erosion

Objectives. To investigate, in vitro, the potential dental effects of diluting juices by measuring their acidity levels and to examine the effect dilution has on the potential erosive properties of the drinks.

Methods. Four commonly available diluting drinks were assessed for both pH and titratable acidity at a variety of dilutions, reflecting the range of concentrations over which such drinks may be consumed. Predetermined dilutions of citric acid and hydrochloric acid, with similar pH values to those of the drinks, were used as positive control acidic solutions. The pH measurements throughout the study were made using a pH electrode connected to an Orion EA940 IonAnalyser.

Results. All four drinks demonstrated a high degree of resistance to a rise in pH, indicating high intrinsic buffering capacity. The measured pH changed very little with increasing dilution ratio when compared to the citric and hydrochloric acid controls, even when considered extremely dilute. In contrast, the titratable acidity of each of the drinks reduced proportionally with increasing dilution, thereby reducing considerably its erosive potential.

Conclusions. While dilution had very little effect on the measured pH values, the titratable acidity reduced as the drink became more dilute. Since there appears to be a direct relationship between dilution and titratable acidity, the erosive potential of diluting juices may be reduced substantially by the addition of water. It remains unlikely, however, that the drinks would ever be consumed at a ‘safe’ level of dilution due to diminished taste and colour.     

菌斑固相消耗糖后缓冲容量的变化与龋易感性的关系

目的研究牙菌斑固相代谢糖后缓冲容量的变化与龋易感性的关系。方法选择成年高龋者(DMFS≥10,DS≥5)及无龋者(DMFS=0)各10名,分别取4种糖消耗情形下的牙菌斑,即基线菌斑、一次漱糖后即刻菌斑、持续耗糖菌斑和漱糖后恢复期菌斑。样本经离心干燥获得菌斑固相成分,以25mmol/LKCl制备10mg/ml的混悬液,用0.1mmol/LHCl滴定以测定初始pH至pH4的缓冲总量和pH5.2~4区段的缓冲容量,同时对各组进行细菌计数。结果消耗糖后菌斑固相的缓冲总量均比基线值(208.793±73.338μmolH /g)低,在pH5.2~4区段,一次耗糖即刻和漱糖前的缓冲容量相同,分别为112.243±28.124μmolH /g和124.773±27.886μmolH /g,持续耗糖后下降至93.358±18.356μmolH /g,恢复期菌斑固相的缓冲容量(144.905±36.857μmolH /g)显著上升。不同龋易感个体缓冲容量间的差异并无显著性。结论糖消耗过程影响菌斑固相的缓冲力,缓冲容量可能不是一个指示龋易感性的敏感指标。     

五禽戏锻炼对中老年女性膝关节肌力及平衡能力影响的临床研究

目的观察五禽戏锻炼对中老年女性膝关节肌力及平衡能力的影响。方法将56例中老年女性志愿者采用类实验的方法分为干预组与对照组,每组28例。干预组进行五禽戏锻炼,对照组进行拉伸锻炼。两组均干预12个月,观察比较膝关节等速肌力测试指标及Berg平衡量表评分(以下简称Berg评分)的变化情况。结果 (1)干预组组内各时点比较:右膝伸肌、左膝屈肌T1与T2的PW比较,差异有统计学意义(P0.05);左右膝关节屈、伸肌T2与T3的PW比较,差异均无统计学意义(P0.05);左右膝关节屈、伸肌T1与T3的PW比较,差异均有统计学意义(P0.05)。对照组组内各时点比较:左右膝关节屈、伸肌T1、T2、T3时点分别两两相比,PW差异均无统计学意义(P0.05)。(2)组间T3时比较,两组左右膝伸肌的PW差异均有统计学意义(P0.05),而两组左右膝屈肌的PW差异均无统计学意义(P0.05)。(3)干预组组内各时点比较:T1、T2、T3两两比较时,Berg评分差异均有统计学意义(P0.05)。对照组组内各时点比较:T1与T2、T1与T3比较时,Berg评分差异均有统计学意义(P0.05);T2与T3比较,Berg评分差异无统计学意义(P0.05)。组间T3时比较,两组Berg评分差异有统计学意义(P0.05)。结论五禽戏锻炼可以提高中老年女性膝关节相关肌力,起到延缓肌力下降、提高平衡能力的作用。     

Impaired oxidative status as a potential predictor in clinical manifestations of herpes zoster

Oxidative stress, caused by an imbalance between reactive oxygen species and antioxidants, is related to many dermatologic diseases. Increased reactive oxygen species is also associated with various decreased T‐cell immune responses. The incidence and severity of herpes zoster (HZ), which is caused by the reactivation of varicella ‐ zoster virus, increase with age because of declining cell‐mediated immunity. The main purpose of this study was to assess the levels of oxidative stress biomarkers in patients with HZ compared with control subjects. In this case‐control study, the serum levels of total antioxidant capacity (TAC), total oxidant status (TOS), oxidative stress index, glutathione, superoxide dismutase, and total polyphenol content (TPC) in 43 patients with HZ and 47 age‐matched controls were determined, and their biomarker patterns were compared. TAC and TPC levels were significantly lower in patients with HZ; however, TOS and oxidative stress index levels were significantly higher in comparison with the control (P < .001). In addition, a signi?cantly strong negative correlation was found between TAC and TPC with TOS levels in patients with HZ (r = ?.79, P < .001; r = ?.81, P < .001, respectively). Our findings showed an oxidative stress imbalance in HZ. Whether this change correlates with HZ pathogenesis or is a consequence of the inflammatory response to HZ needs more investigation.     

Time‐dependent changes in bone healing capacity of scaphoid fractures and non‐unions

The scaphoid is the most frequently fractured carpal bone and prone to non‐union due to mechanical and biological factors. Whereas the importance of stability is well documented, the evaluation of biological activity is mostly limited to the assessment of vascularity. The purpose of this study was to select histological and immunocytochemical parameters that could be used to assess healing potential after scaphoid fractures and to correlate these findings with time intervals after fracture for the three parts of the scaphoid (distal, gap and proximal). Samples were taken during operative intervention in 33 patients with delayed or non‐union of the scaphoid. Haematoxylin and Eosin (HE ), Azan, Toluidine, von Kossa and Tartrate‐resistant acid phosphatase (TRAP ) staining were used to characterise the samples histologically. We determined distribution of collagen 1 and 2 by immunocytochemistry, and scanning electron microscopy (SEM ) was used to investigate the ultrastructure. To analyse the samples, parameters for biological healing status were defined and grouped according to healing capacity in parameters with high, partial and little biological activity. These findings allowed scoring of biological healing capacity, and the ensuing results were correlated with different time intervals after fracture. The results showed reduced healing capacity over time, but not all parts of the scaphoid were affected in the same way. For the distal fragment, regression analysis showed a statistically significant correlation between summarised healing activity scores and time from initial fracture (r  = ?0.427, P  = 0.026) and decreasing healing activity for the gap region (r  = ?0.339, P  = 0.090). In contrast, the analyses of the proximal parts for all patients did not show a correlation (r  = 0.008, P  = 0.969) or a decrease in healing capacity, with reduced healing capacity already at early stages. The histological and immunocytochemical characterisation of scaphoid non‐unions (SNU s) and the scoring of healing parameters make it possible to analyse the healing capacity of SNU s at certain time points. This information is important as it can assist the surgeon in the selection of the most appropriate SNU treatment.     

Functional morphology of the respiratory organs of the air-breathing fish with particular emphasis on the African catfishes, Clarias mossambicus and C. gariepinus

The evolution of air-breathing and transition from water to land were pivotal events that greatly determined the ecological diversification, the advances and the successes of animal life. During their relocation onto land, the so-called bimodal breathers were literally caught at the water-air interface. Among such animals are the diverse air-breathing bony fish. Such taxa, however, strictly do not constitute the so-called ‘bridging animals’, i.e., the inaugural animals that crossed from water to land, nor are they their direct progenitors. The pioneer transitional animals were the Devonian rhipidistian amphibians that possessed a primitive lung which acquired O₂ directly from air and discharged CO₂ back into the same. By having particular morphological and physiological adaptations for terrestrialness, the modern amphibious- and aquatic air-breathers are heuristic analogues of how and why animals relocated from water to land. It has generally been espoused that lack or dearth of O₂ in water, especially in the warm tropical one, was an elemental driver for adoption of air-breathing. There is, however, no direct causal relationship between the evolution of air-breathing and the shift onto land: the move onto land was a direct solution to the existing inimical respiratory conditions in water. This is evinced in the facts that: a) even after attaining capacity of air-breathing, an important preadaptation for life on land, some animals continued living in water while periodically accessing air, b) in the fish species that live in the well-oxygenated waters, e.g., torrential rivers, only few air-breathe and c) air-breathing has still evolved in freshwaters and seawaters, where levels of dissolved O₂ are sufficiently high. Here, the structure and function of the respiratory organs of the air-breathing fish are succinctly outlined. Two African catfishes, Clarias mossambicus and C. gariepinus are highlighted.     

From the Cover: PNAS Plus: Climate change,pink salmon,and the nexus between bottom-up and top-down forcing in the subarctic Pacific Ocean and Bering Sea

Climate change in the last century was associated with spectacular growth of many wild Pacific salmon stocks in the North Pacific Ocean and Bering Sea, apparently through bottom-up forcing linking meteorology to ocean physics, water temperature, and plankton production. One species in particular, pink salmon, became so numerous by the 1990s that they began to dominate other species of salmon for prey resources and to exert top-down control in the open ocean ecosystem. Information from long-term monitoring of seabirds in the Aleutian Islands and Bering Sea reveals that the sphere of influence of pink salmon is much larger than previously known. Seabirds, pink salmon, other species of salmon, and by extension other higher-order predators, are tightly linked ecologically and must be included in international management and conservation policies for sustaining all species that compete for common, finite resource pools. These data further emphasize that the unique 2-y cycle in abundance of pink salmon drives interannual shifts between two alternate states of a complex marine ecosystem.Predator control of community structure and ecosystem function became a tenet of intertidal and nearshore marine ecology following early studies of Paine and others (1–3), yet with few exceptions (4, 5), until more recent times the idea has been less well appreciated for open oceans. Growing attention now is being paid to the overexploitation of pelagic species, particularly those at higher trophic levels currently and in the past, and effects on ocean ecosystems of the loss, or development, of top-down forcing (6–12).The prevailing view has long held that most biological change in ocean ecosystems, apart from human exploitation, is driven from the bottom up (13–16). One striking example that has been linked to bottom-up processes driven by climate change is the burgeoning abundance of wild Pacific salmon (Oncorhynchus spp.), and in particular pink salmon (Oncorhynchus gorbuscha), in the subarctic North Pacific Ocean and Bering Sea (SNPO/BS). Underpinning the notion initially were studies that found (i) strong coherence between decadal patterns in the Aleutian Low pressure system, which exerts a large influence over climate in the North Pacific Ocean, and patterns in salmon production across a broad region of the SNPO/BS (17, 18); (ii) decadal patterns in primary production that could be explained by the effect of the Aleutian Low pressure system on basin scale wind fields (19); and (iii) decadal patterns in zooplankton, squid, and pelagic fish production that also were correlated with meteorological forcing over the North Pacific Ocean and consistent with patterns in primary production (20). Thus, the general explanation for waxing and waning abundances of salmon over the record in the 20th century was that physical forcing by shifts in the strength and position of the Aleutian Low altered winds, ocean temperatures, and primary and secondary production to the benefit or detriment of salmon. A decadal scale oscillation in the Aleutian Low, now often referred to as the Pacific Decadal Oscillation (PDO) (21), has been linked to numerous physical and biological variability in the SNPO/BS in addition to salmon abundance (21–23).It was subsequently shown that salmon population responses and their relation to the PDO were out of phase between Alaska and the northwest coast of North America during much of the 20th century (24); that warm anomalies in coastal temperatures were associated with increased survival of salmon in Alaska; and that regional-scale variability in ocean temperature was a better predictor of salmon survival than large, basin-scale variability characterized by the PDO (25). A recent analysis from around the rim of the North Pacific Ocean found regional covariance in abundance of pink salmon, chum salmon (Oncorhynchus keta), and sockeye salmon (Oncorhynchus nerka) associated with the Aleutian Low, and with smaller scale spatially coherent, but regionally distinct, patterns in climate (26).Water temperature can be important to the early growth and survival of pink salmon fry directly by its effect on physiology and indirectly by its effect on the timing and development of zooplankton prey stocks in nursery areas, which commonly is advanced and greater in warmer years than in cooler years. In cooler springs, fry grow more slowly and a greater number die both from lack of food and from an increased susceptibility to predators (27, 28). For example, a conceptual model for Prince William Sound, Alaska, holds that, in years of abundant spring zooplankton, fry grow faster and remain longer in the shelter of inshore nurseries where they are protected from walleye pollock (Theragra chalcogramma) and Pacific herring (Clupea pallasii), two chief predators that remain offshore feeding primarily on swarms of large calanoid copepods and other macrozooplankton. In cooler years of lower zooplankton biomass inshore, fry grow more slowly, move offshore earlier, and suffer higher predation by pollock and herring due to spatial overlap, smaller size, and less alternative prey for those two predators (28).Although the relationship between climate and pink salmon survival is likely complex, fluctuations in abundance appear to be modulated in large measure directly and indirectly by the thermal environment in which a stock lives. Such a fundamentally bottom-up explanation is bolstered by observations of high growth and survival rates of pink salmon during the period of warmer ocean temperatures and population increase (29, 30), and at this time provides a more parsimonious explanation for population dynamics than would explanations invoking strictly top-down control across such a broad region. Now, however, several lines of evidence indicate that pink salmon themselves are having a large top-down influence on other salmon species, other upper trophic level pelagic species, plankton standing stocks, and by inference, the functioning of the open-ocean ecosystem in the SNPO/BS.