A survey of the 2010 quartz crystal microbalance literature

In 2010 there has again been an increase in the number of papers published involving piezoelectric acoustic sensors, or quartz crystal microbalances (QCM), when compared to the last period reviewed 2006‐2009. The average number of QCM publications per annum was 124 in the period 2001‐2005, 223 in the period 2006‐9, and 273 in 2010. There are trends towards increasing use of QCM in the study of protein adsorption to surfaces (93% increase), homeostasis (67% increase), protein‐protein interactions (40% increase), and carbohydrates (43% increase). New commercial systems have been released that are driving the uptake of the technology for characterisation of binding specificities, affinities, kinetics and conformational changes associated with a molecular recognition event. This article highlights theoretical and practical aspects of the principals that underpin acoustic analysis, then reviews exemplary papers in key application areas involving small molecular weight ligands, carbohydrates, proteins, nucleic acids, viruses, bacteria, cells, and membrane interfaces. Copyright © 2012 John Wiley & Sons, Ltd.     

A survey of the 2001 to 2005 quartz crystal microbalance biosensor literature: applications of acoustic physics to the analysis of biomolecular interactions

The widespread exploitation of biosensors in the analysis of molecular recognition has its origins in the mid-1990s following the release of commercial systems based on surface plasmon resonance (SPR). More recently, platforms based on piezoelectric acoustic sensors (principally 'bulk acoustic wave' (BAW), 'thickness shear mode' (TSM) sensors or 'quartz crystal microbalances' (QCM)), have been released that are driving the publication of a large number of papers analysing binding specificities, affinities, kinetics and conformational changes associated with a molecular recognition event. This article highlights salient theoretical and practical aspects of the technologies that underpin acoustic analysis, then reviews exemplary papers in key application areas involving small molecular weight ligands, carbohydrates, proteins, nucleic acids, viruses, bacteria, cells and lipidic and polymeric interfaces. Key differentiators between optical and acoustic sensing modalities are also reviewed.     

EVIDENCE FOR INCREASES IN ANTARCTIC BLUE WHALES BASED ON BAYESIAN MODELLING

Antarctic blue whales ( Balaenoptera musculus intermedia ) are the largest and formerly most abundant blue whale subspecies, but were hunted to near extinction last century. Estimated whaling mortality was unsustainable from 1928 to 1972 (except during 1942–1944), depleting them from 239,000 (95% interval 202,000–311,000) to a low of 360 (150–840) in 1973. Obtaining statistical evidence for subsequent increases has proved difficult due to their scarcity. We fitted Bayesian models to three sighting series (1968–2001), constraining maximum rates of increase to 12% per annum. These models indicated that Antarctic blue whales are increasing at a mean rate of 7.3% per annum (1.4%–11.6%). Informative priors based on blue whale biology (4.3%, SD = 1.9%) and a Bayesian hierarchical meta-analysis of increase rates in other blue whale populations (−3%, SD = 11.6%), suggest plausible increase rates are lower (although the latter has wide intervals), but a meta-analysis of other mysticetes obtains similar rates of increase (6.7%, SD = 4.0%). Possible biases affecting the input abundance estimates are discussed. Although Antarctic blue whales appear to have been increasing since Sovier illegal whaling ended in 1972, they still need to be protected-their estimated 1996 population size, 1,700 (860–2,900), was just 0.7% (0.3%–1.3%) of the pre-exploitation level.     

Population size and trends of southern giant petrels (<Emphasis Type="Italic">Macronectes giganteus</Emphasis>) nesting at Signy Island,South Orkney Islands

The southern giant petrel (Macronectes giganteus) has a circumpolar distribution and breeds on subantarctic islands and a few continental Antarctic sites. Although this species has recently been down-listed to “Least Concern” by the World Conservation Union (IUCN), there are strong fluctuations in abundance and variable long-term trends recorded at different sites. Systematic, long-term monitoring is essential to determine drivers underlying its population dynamics. Here, we examine long-term changes in population size and productivity of southern giant petrels at Signy Island, South Orkney Islands. Comparing estimated numbers of breeding pairs over the whole island in 2000/2001, 2005/2006, 2009/2010 and 2014/2015 with historical data revealed several phases of population change: a 64 % decline (6.2 % per annum) from 1968/1969 to 1984/1985, a 162 % increase (6.2 % per annum) to 2000/2001, stability until 2005/2006, a 56 % decline (18.3 % per annum) to 2009/2010 and stability until 2014/2015. This represents a 1.8 % decline per annum between 1968/1969 and 2014/2015. Annual counts within focal study areas suggested a more rapid increase from 1996/1997 to 2006/2007, but the same downward trend from 2006/2007 to present, underlining potential pitfalls in inferring trends from part-island counts. There was also a 20 % decline in breeding success from 1996/1997 to 2014/2015. Our results indicate substantial fluctuations in southern giant petrel abundance at Signy Island over 4–5 decades and a recent decline in breeding numbers and success. As the southern giant petrels breeding at the South Orkney Islands represents ~5–10 % of the global population, continuation of these declines would be of high conservation concern.     

A 28-YEAR STUDY OF BREEDING FULMARS FULMARUS GLACIALIS IN ORKNEY

Colour-ringed breeding Fulmars were studied on the island of Eynhallow, Orkney, from 1950 onwards.
During the 28 years, there was an average increase in population size of about 4% (9 birds) per annum, standard deviation 23%, The mean population size was 161 birds, with about 22 new breeders and 26 new nest sites per annum. There were marked fluctuations in numbers of birds and occupied sites per annum, causing deviations from the underlying trend.
Most nest sites were on the coast. The distribution of occupied nests was variable, the most favoured areas changing over the years.
A mean of 46 chicks fledged per annum. The proportion of breeding pairs which fledged a chick varied from 16 to 52% (even though there was no known change in conditions). Success in small areas sometimes differed considerably from that of the island as a whole.
Although most fledglings were ringed, only 3% have returned and bred on Eynhallow. Between 89 and 94% of those which survived to breeding age must have bred elsewhere.
It was concluded that the population size and breeding success of small areas could differ quite markedly from that on a wider scale and could vary quite markedly over the years, facts that have important implications for monitoring of seabird colonies.     

Proficiency testing in cytology laboratories in Ontario, Canada: a decade of experience. I. Introduction and description of the testing model

There are few formally documented proficiency testing programs for cytology laboratories, and those that have been documented are not entirely comparable in format. The first of three papers documenting a mandatory universal proficiency testing program for cytology laboratories in the Province of Ontario, Canada, presents data on the structure and function of the participating laboratories (including a comparison of the data for 1974 and 1980) and on the organization of the testing model (including selection of terminology, construction and use of the survey and assessment of responses). In 1980, of the 463 medical laboratories in Ontario, 91 of 222 hospital laboratories and 65 of 216 nonhospital laboratories were licensed in cytology. In that year, the 156 cytology laboratories processed 1.48 million cytology specimens, 92% of which were gynecologic. Hospital laboratories processed 87.5% of the nongynecologic cytology specimens and 30% of the gynecologic cytology specimens. These proportions have been virtually constant for several years. Between 1974 and 1980, there was a trend in Ontario to fewer laboratories processing less than 5,000 cytology specimens per annum. Subsequent papers in this series describe the results of the initial surveys in this program and a precision study to evaluate the consistency of reporting by individual laboratories.     

Quartz Crystal Microbalance with Dissipation Monitoring: Enabling Real-Time Characterization of Biological Materials and Their Interactions

In recent years, there has been a rapid growth in the number of scientific reports in which the quartz crystal microbalance (QCM) technique has played a key role in elucidating various aspects of biological materials and their interactions. This article illustrates some key advances in the development of a special variation of this technique called quartz crystal microbalance with dissipation monitoring (QCM-D). The main feature and advantage of QCM-D, compared with the conventional QCM, is that it in addition to measuring changes in resonant frequency (Δf), a simultaneous parameter related to the energy loss or dissipation (ΔD) of the system is also measured. Δf essentially measures changes in the mass attached to the sensor surface, while ΔD measures properties related to the viscoelastic properties of the adlayer. Thus, QCM-D measures two totally independent properties of the adlayer. The focus of this review is an overview of the QCM-D technology and highlights of recent applications. Specifically, recent applications dealing with DNA, proteins, lipids, and cells will be detailed. This is not intended as a comprehensive review of all possible applications of the QCM-D technology, but rather a glimpse into a few highlighted application areas in the biomolecular field that were published in 2007.     

Cutaneous malignant melanoma in Scotland: incidence,survival, and mortality, 1979-94. The Scottish Melanoma Group.

OBJECTIVE: To determine the changing incidence of and mortality from cutaneous malignant melanoma in Scotland from 1979 to 1994. DESIGN: Detailed registration of clinical and pathological features, surgical and other treatment, and follow up of all cases of cutaneous malignant melanoma diagnosed from 1979 to 1994 and registered with specialist database for Scotland. SETTING: Scotland. SUBJECTS: 6288 patients with invasive primary cutaneous malignant melanoma diagnosed between 1 January 1979 and 31 December 1994. RESULTS: The annual age standardised incidence of cutaneous malignant melanoma rose significantly from 3.5 to 7.8 per 100,000 per year in men and from 6.8 to 12.3 per 100,000 per year in women (P < 0.001 for both). World standardised rates increased from 2.7 to 6.0 per 100,000 per year in men and 4.6 to 8.50 per 100,000 in women. The incidence of melanoma continued to increase significantly in men of all ages during the study, but the rate stabilised in women after 1986. Mortality from cutaneous malignant melanoma was 1.3 per million per annum in men in 1979, rising to 2.3 per million per annum in 1994 (P < 0.01); it was 2.4 per million per annum in women in 1979, falling to 1.9 per million per annum in 1994 (P = 0.09). The underlying mortality trends showed a continuing rise for men but a downward trend for women that was not significant (P = 0.09). In men, melanoma free survival was 69% at 5 years and 61% at 10 years; in women the corresponding rates were 82% and 75%. Younger patients had higher survival rates, which were not entirely explained by thinner tumours. Over the 15 year period, survival rates improved by 12% overall, only partly owing to thinner tumours. CONCLUSIONS: In Scotland the incidence of melanoma in women has stabilised, while mortality associated with melanoma in women shows a downward trend.     

Ultrasensitive quartz crystal microbalance sensors for detection of M13-Phages in liquids

Quartz crystal microbalance (QCM) sensors are widely used for determining liquid properties or probing interfacial processes. For some applications the sensitivity of the QCM sensors typically used (5–20 MHz) is limited compared with other biosensor methods. In this study ultrasensitive QCM sensors with resonant frequencies from 39 to 110 MHz for measurements in the liquid phase are presented. The fundamental sensor effect of a QCM is the decrease of the resonant frequency of an oscillating quartz crystal due to the binding of mass on a coated surface during the measurement. The sensitivity of QCM sensors increases strongly with an increasing resonant frequency and, therefore, with a decreasing thickness of the sensitive area. The new kind of ultrasensitive QCM sensors used in this study is based on chemically milled shear mode quartz crystals which are etched only in the center of the blank, forming a thin quartz membrane with a thick, mechanically stable outer ring. An immunoassay using a virus specific monoclonal antibody and a M13-Phage showed an increase in the signal to noise ratio by a factor of more than 6 for 56 MHz quartz crystals compared with standard 19 MHz quartz crystals, the detection limit was improved by a factor of 200. Probing of acoustic properties of glycerol/water mixtures resulted in an increase in sensitivity, which is in very good agreement with theory. Chemically milled QCM sensors strongly improve the sensitivity in biosensing and probing of acoustic properties and, therefore, offer interesting new application fields for QCM sensors.     

Growth of Mantled Howler Groups in a Regenerating Costa Rican Dry Forest

We examined population dynamics in mantled howlers (Alouatta palliata palliata) in a regenerating tropical dry forest in Santa Rosa National Park (SRNP), Costa Rica. The population has grown at a rate of about 7% per annum during the past decade. The growth in numbers from 342 in 1984 to 554 in 1992 reflects an increase in the number of groups (from 25 to 34) and a slight increase in their average size (from 13.6 to 16.3). Population density has increased from 4.9 to 7.9 individuals per km ². Santa Rosa's population density and group compositions are similar to those at several other mantled howler sites, but densities of mantled howlers are much higher at two other well-studied sites: La Pacifica and Barro Colorado Island (BCI). We relate the low density of howlers at Santa Rosa to local historical and ecological factors. Howler populations at high and low densities differ in average group size and sex ratio. At high population densities, groups are larger and include more adult females. The number of male howlers per group appears to be more strictly limited and less variable than the number of females is. However, there is greater variation in male group membership at Santa Rosa than at La Pacifica or BCI, and at Santa Rosa there are more generating forests available into which males and females can disperse and form new groups. We present case studies describing two ways in which new howler groups are formed, and we suggest that, compared to females and compared to males at high density sites, males are relatively advantaged in the uncrowded habitats at Santa Rosa and other low density sites.     

Acoustic wave immunosensing of a meningococcal antigen using gold nanoparticle-enhanced mass sensitivity

Bacterial meningitis is an infection of the thin membranes covering the brain and spinal cord by a number of microorganisms including Neisseria meningitidis, which can lead to permanent neurological damage in the event of late diagnosis. Given the quick onset and severity of the disease, there is a clear need for a rapid, sensitive and specific diagnostic technique. Here, we describe the development and evaluation of an acoustic wave sensor, the quartz crystal microbalance (QCM), as a rapid immunosensor employing antibodies against the cell surface outer membrane protein 85 (OMP85) of N. meningitidis as an immobilized selective layer. These antibodies were directionally orientated as receptors by thin film deposition of structured polyvinylidene fluoride and Protein A. The sensitivity of this QCM immunosensor was further increased by conjugation of the OMP85 antigen to 50 nm gold nanoparticles providing reproducible detection of the target down to 300 ng/mL. Subsequent treatment of the QCM surface with an acidic glycine solution regenerated the immunosensor allowing each crystal to be used several times.     

The quartz crystal microbalance as a continuous monitoring tool for the study of endothelial cell surface attachment and growth

The quartz crystal microbalance (QCM) was used to monitor endothelial cell (EC) adhesion on the gold surface of an oscillating quartz crystal contained in a QCM device. A number of parameters were investigated. First, we observed differential QCM O-ring toxicities for ECs. Second, appropriate conditions for cell culture and QCM cell environment were identified that can eliminate large-scale frequency oscillations in the measurements. These artifacts are not due to added cells but originate in the time-dependent evaporation of water. Having eliminated these artifacts, we then demonstrated that the measured steady-state crystal frequency shift, Delta f, and motional resistance shift, DeltaR, were determined by the number of firmly attached ECs requiring trypsinization from the crystal surface. Last, following steady-state attachment of ECs, the EC growth stimulation by fibroblast growth factor was monitored in a continuous fashion by measuring f and R values over a 72 h. period. We observed the Delta f values to increase in a way that reflected the increase in EC number bound to the QCM surface. Following addition of ECs to the QCM, the time-dependent increase in DeltaR can be interpreted in terms of increase by the ECs of the energy dissipation properties of the solution at the solution-gold surface interface. This effect is due to their rapid surface attachment and the elaboration of their cytoskeletal properties. These results indicate that the QCM technique can be used for the study of EC attachment and growth and suggest its potential for the real time study of per unit surface area cell mass distribution dynamics and viscoelastic properties and the cells' responses to stresses or perturbations brought about using biologically active molecules.     

IgG binding kinetics to oligo B protein A domains on lipid layers immobilized on a 27 MHz quartz-crystal microbalance

Although molecular recognitions between membrane receptors and their soluble ligands have been analyzed using their soluble proteins in bulk solutions, molecular recognitions of membrane receptors should be studied on lipid membranes considering their orientation and dynamics on membrane surfaces. We employed Staphylococcal Protein A (SpA) oligo B domains with long trialkyl-tags from E. coli (LppBx, x = 1, 2, and 5) and immobilized LppBx on lipid layers using hydrophobic interactions from the trialkyl-tag, while maintaining the orientation of B domain-chains on a 27 MHz quartz-crystal microbalance (QCM; AT-cut shear mode). The binding of IgG Fc regions to LppBx on lipid layers was detected by frequency decreases (mass increases) on the QCM. The maximum amount bound (Delta m(max)), association constants (K(a)), association and dissociation rate constants (k(1) and k(-1), respectively) were obtained. Binding kinetics of IgG to LppB2 and LppB5 were quite similar, showing a simple 1:1 binding of the IgG Fc region to the B domain, when the surface coverage of LppB2 and LppB5 on the lipid surface is low (1.4%). When LppB5 was immobilized at the high surface coverage of 3.5%, the complex bindings of IgG such as one IgG bound to one or two LppB5 on the membrane could be observed. IgG-LppB1 binding was largely restricted because of steric hindrance on lipid surfaces. This gives a suggestion why Protein A has five IgG binding domains.     

长江江豚种群衰退机理研究进展

长江江豚（Neophocaena phocaenoides asiaeorientalis）是生活于我国长江中下游的一种独特的淡水小型鲸类,1996年被收录为IUCN濒危物种。在过去的三十年间,其种群数量呈快速下降趋势。数据显示,20世纪90年代以来,其种群下降速率约为每年6.3%。2006年考察发现长江干流中其种群数量少于1 200头,与15年前相比减少了50%以上。为了深入了解造成长江江豚种群快速衰退的机理,课题组从种群生态学、生物声学和种群遗传学三个方面开展研究工作。综述了该项目的研究进展,并对下一步的研究计划进行了展望。相关研究不仅能促进长江江豚保护生物学理论的发展,也有助于深化对白鱀豚衰退和灭绝过程的反思,并为其他长江水生生物资源的保护提供理论借鉴。     

Evolutionary physiology by data of publications for 1965–2005

Evolutionary physiology as independent direction of physiology was formed in the XX century and was rapidly developing in its second half. To evaluate some tendencies of this process, we analyzed publications in Journal of Evolutionary Biochemistry and Physiology, one of the leading specialized periodicals on this problem. Analysis of works published for 4 decades has shown that the majority of papers deals with study of evolution of function of the nervous system (40–60 papers per year), less papers concern study of functions of sensory and visceral systems (20–30 per year). Among the used method, the most widely spread is the comparative-physiological method. By the end of the 1990s the number of works with use of methods of embryophysiology decreased. In the performed studies, predominant are physiological methods. Use of biochemical methods decreased, while of methods of molecular biology increased. The most often used objects of studies were mammals. By the end of the XX—beginning of the XXI century, in the greater number of papers the object of study has become human, while the number of publications in which experiments were performed on amphibians, reptiles, and birds decreased. More than a half of all works were carried out in St. Petersburg (Leningrad); the number of papers submitted from Moscow institutions gradually decreased, but the number of works from regions of Russia rose. Most studies were performed at institutes of the Russian Academy of Sciences and universities, while the number of papers from institutes of the Russian Academy of Medical Sciences decreased. For the last few years, several generalizations on evolution of functions and functional evolution have been formulated; handbooks and monographs on problems of evolutional physiology have been published.     

Propagation,growth, and carbohydrates of <Emphasis Type="Italic">Dendrobium</Emphasis> Second Love (Orchidaceae) <Emphasis Type="Italic">in vitro</Emphasis> as affected by sucrose,light, and dark

In general, plant material grown in vitro has low photosynthetic ability to achieve positive carbon balances. Therefore, a continuous supply of carbohydrates from the culture medium is required, and sucrose has been the most commonly used carbon source. In this paper, we investigate the effects of different sucrose concentrations and the presence and absence of light on the endogenous levels of soluble carbohydrates and starch as well as on the proliferation and growth of Dendrobium Second Love (Orchidaceae) in vitro. The possibility of using etiolated stem segments as a means for micropropagating this hybrid was also verified. The results obtained indicated that the presence and absence of light and the sucrose concentrations used influenced the amounts of soluble carbohydrates and starch and the proliferation of D. Second Love shoots and roots. An increase in sucrose concentration caused a progressive increase in the amounts of total carbohydrates and starch. Under both light conditions, sucrose was the main sugar found in the shoots followed by glucose and fructose. The addition of sucrose to the culture medium up to 2% and 4% was advantageous to the number of shoots produced per explant and the root longitudinal growth in the presence and absence of light, respectively. Shoot and root dry matter and the number of roots formed per explant increased as sucrose concentration was raised up to 6% in both light treatments. The use of dark-grown shoot segments proved to be a useful and reliable alternative for the micropropagation of this hybrid.     

Eighteen years of saturation tagging data reveal a significant increase in nesting hawksbill sea turtles (Eretmochelys imbricata) on Long Island, Antigua

Hawksbill sea turtle Eretmochelys imbricata nesting on Long Island, Antigua, West Indies (also known as Jumby Bay) has been monitored since 1987. Although the numbers of nesting females remained relatively constant for the first 11 survey seasons (1987–1997), inclusion of more recent data (1998–2004) in the analysis reveals a statistically significant upward trend. In particular, neophytes have shown a significant upturn in numbers, whereas the remigrant subpopulation has remained stationary. This indicates that recruitment is driving the upward trend in the total number of nesters. Predictive models based on the Poisson distribution suggest that the neophyte subpopulation will continue to grow in size by an average of 10% per annum. Model-based predictions and their limitations are discussed. The Jumby Bay Hawksbill Project, which has monitored and protected nesting hawksbills and their eggs since the project's onset, is one among several factors that may contribute to the recent increase in nesting females.     

STATISTICAL METHODS FOR ESTIMATING NUMBERS OF CAPE FUR SEAL PUPS FROM AERIAL SURVEYS

The Cape fur seal Arctocephalus pusillus of South Africa and Namibia breeds in 23 colonies. Aerial surveys have been used to estimate numbers of pups during breeding seasons from December 1971 to December 1978, and the results have been presented by Shaughnessy (1987). In this paper we develop statistical methods for estimating these pup numbers, as well as variances of the estimates. We demonstrate a significant increase in numbers of seal pups between 1971 and 1976; the rate of increase is estimated to be 3.2% per annum.     

Survey of the year 2004: literature on applications of isothermal titration calorimetry

The market for commercially available isothermal titration calorimeters continues to grow as new applications and methodologies are developed. Concomitantly the number of users (and abusers) increases dramatically, resulting in a steady increase in the number of publications in which isothermal titration calorimetry (ITC) plays a role. In the present review, we will focus on areas where ITC is making a significant contribution and will highlight some interesting applications of the technique. This overview of papers published in 2004 also discusses current issues of interest in the development of ITC as a tool of choice in the determination of the thermodynamics of molecular recognition and interaction.     

Gravimetric biosensors based on acoustic waves in thin polymer films

Most gravimetric biosensors use thin piezoelectric quartz crystals, either as resonating crystals (quartz crystal microbalance, QCM), or as bulk/surface acoustic wave (SAW) devices. In the majority of these the mass response is inversely proportional to the crystal thickness which, at a limit of about 150 microns, gives inadequate sensitivity. A new system is described in which acoustic waves are launched in very thin (10 microns) tensioned polymer films to produce an oscillatory device. A theoretical equation for this system is almost identical to the well-known Sauerbrey equation used in the QCM method. Because the polymer films are so thin, a 30-fold increase in sensitivity is predicted and verified by adding known surface masses. Temperature sensitivity is a problem so a separate control sensor and careful temperature regulation are necessary. Preliminary results showing the real time binding of protein (IgG), a step towards immunosensor development, and the use of mass enhancing particles are presented. Inexpensive materials are used so disposable gravimetric biosensors may become feasible.