An Experimental Study of the Effect of Strontium Pre-Treatment on Calcium Release From Carious and Non-Carious Teeth

The administration of strontium salt is known to be beneficial for bones in preventing calcium loss and osteoporosis. Therefore, we decided to study if strontium treatment affects calcium release from teeth in vitro. Extracted carious as well as non-carious teeth were washed, cleaned, and dried. These were individually immersed in 25 ml of 1% lactic acid at 37oC for 24 h, and the amount of calcium released was measured. The rate of calcium release from these teeth was again determined after their exposure to M/4 strontium chloride for 1 month at 37°C. It was found that: (1) the rate of calcium release from non-carious teeth was significantly higher than carious teeth, possibly because there was more calcium present, (2) the rate of calcium release was almost halved after strontium treatment in both groups of teeth, (3) the Vicker’s microhardness of non-carious teeth was higher than those of carious teeth, and (4) strontium treatment did not affect hardness. Strontium treatment may be beneficial in reducing loss of calcium from intact teeth—non-carious as well as carious—and this beneficial effect of strontium is unrelated to change in teeth hardness.     

On the extinction of the Dune Shearwater (Puffinus holeae) from the Canary Islands

Insular ecosystems have been subjected to severe hardship during the last millennia. Large numbers of insular bird species have undergone local disappearances and full extinctions, and a high number of insular birds are currently categorised as endangered species. In most of these cases, extinction—or endangerment—is in direct relation to the arrival of ‘aboriginal’ and/or imperialist waves of human settlement. Insular bird extinction events have been documented to have occurred at times corresponding to aboriginal settlement at many archipelagos and isolated islands, such as the Hawaiian Islands, New Zealand, the West Indies or the tropical Pacific Islands. However, no bird extinctions could be attributed to the first settlers of the Canary Islands—until now. The first accelerator mass spectrometer radiocarbon (¹⁴C) dating of collagen from a bone of the Dune Shearwater Puffinus holeae (3395 ± 30 year BP), an extinct bird from the Canary Islands, indicates a late Holocene extinction event. This relatively recent date, together with some features of this bird (large body size, breeding areas situated at very accessible places) and the absence of its bones from the entire archaeological record suggests that the extinction occurred close to the time that the first human settlement occurred on the islands.     

Pore Formation by S. aureus α-toxin in Liposomes and Planar Lipid Bilayers: Effects of Nonelectrolytes

Nonelectrolytes such as polyethylene glycols (PEG) and dextrans (i) promote the association of S. aureus α-toxin with liposomes (shown by Coomassie staining) and (ii) enhance the rate and extent of calcein leakage from calcein-loaded liposomes; such leakage is inhibited by H⁺, Zn²⁺ and Ca²⁺ to the same extent as that of nonPEG-treated liposomes. Incubation of liposomes treated with α-toxin in the presence of PEG with the hydrophobic photo-affinity probe 3-(trifluoromethyl)-3-m-[¹²⁵I]iodophenyl)diazirine(¹²⁵I-TID) labels monomeric and—predominantly—hexameric forms of liposome-associated α-toxin; in the absence of PEG little labeling is apparent. At high concentrations of H⁺ and Zn²⁺ but not of Ca²⁺—all of which inhibit calcein leakage—the distribution of label between hexamer and monomer is perturbed in favor of the latter. In α-toxin-treated planar lipid bilayers from which excess toxin has been washed away, PEGs and dextrans strongly promote the appearance of ion-conducting pores. The properties of such pores are similar in most regards to pores induced in the absence of nonelectrolytes; they differ only in being more sensitive to ``closure' by voltage (as are pores induced in cells). In both systems, the stimulation by nonelectrolytes increases with concentration and with molecular mass up to a maximum around 2,000 Da. We conclude (i) that most of the α toxin that becomes associated with liposome or planar lipid bilayers does not form active pores and (ii) that the properties of α-toxin-induced pores in lipid bilayers can be modulated to resemble those in cells. Received: 2 October 1995/Revised: 3 November 1995     

Large-amplitude ion acoustic solitons in a bi-ion plasma

A gas-dynamic model is used to study the conditions for the existence of large-amplitude ion acoustic solitons in a plasma with negative ions. It is shown that the limiting Mach number—the upper boundary of the region of existence of compression solitons—depends nonmonotonically on the temperature of the positive ions. The result is that, for certain fixed densities of the negative ions, there are one or two temperature boundaries between the regions where solitons can and cannot exist. It is found that, for rarefaction solitons, it is fundamentally important to take into account electron inertia and that the Mach number of such solitary waves is restricted not by the complete decompression of electrons within the wave (as thought previously), but by the fact that the electrons at the center of the wave reach the acoustic speed, above which the thermal-pressure-induced action cannot be transferred back to the electron flow and smooth continuous solutions are impossible.     

Tuning the cochlea: wave-mediated positive feedback between cells

Frequency analysis by the mammalian cochlea is traditionally thought to occur via a hydrodynamically coupled ‘travelling wave’ along the basilar membrane. A persistent difficulty with this picture is how sharp tuning can emerge. This paper proposes, and models, a supplementary or alternative mechanism: it supposes that the cochlea analyses sound by setting up standing waves between parallel rows of outer hair cells. In this scheme, multiple cells mutually interact through positive feedback of wave-borne energy. Analytical modelling and numerical evaluation presented here demonstrate that this can provide narrow-band frequency analysis. Graded cochlear tuning will then rely on the distance between rows becoming greater as distance from the base increases (as exhibited by the actual cochlea) and on the wave’s phase velocity becoming slower. In effect, tuning is now a case of varying the feedback delay between the rows, and a prime candidate for a wave exhibiting suitably graded phase velocity—a short-wavelength ‘squirting wave’—is identified and used in the modelling. In this way, resonance between rows could supply both amplification and high Q, characteristics underlying the ‘cochlear amplifier’—the device whose action has long been evident to auditory science but whose anatomical basis and mode of operation are still obscure.     

Epicatechin Inhibits Human Plasma Lipid Peroxidation Caused by Haloperidol In Vitro

Epicatechin belongs to flavonoids protecting cells against oxidative/nitrative stress. Oxidative/nitrative stress observed in schizophrenia may be caused partially by the treatment of patients with various antipsychotics. The aim of our study was to establish the effects of epicatechin and antipsychotics action (the first generation antipsychotic (FGA)—haloperidol and the second generation antipsychotic (SGA)—amisulpride) on peroxidation of plasma lipids in vitro. Lipid peroxidation in human plasma was measured by the level of thiobarbituric acid reactive species (TBARS). The properties of epicatechin were also compared with the action of a well characterized antioxidative commercial polyphenol—resveratrol (3,4′,5-trihydroxystilbene) and quercetin (3,5,7,3′,4′-pentahydroxyflavone). Amisulpride, contrary to haloperidol (after 1 and 24 h) does not significantly influence the increase of plasma TBARS level in comparison with control samples (P > 0.05). After incubation (1 and 24 h) of plasma with haloperidol in the presence of epicatechin we observed a significantly decreases the level of TBARS (P < 0.001, P < 0.001, respectively). In our other experiments, we found that epicatechin also decreased the amount of TBARS in human plasma treated with amisulpride. In conclusion, the presented results indicate that epicatechin—the major polyphenolic component of green tea reduced significantly human plasma lipid peroxidation caused by haloperidol. Moreover, epicatechin was found to be a more effective antioxidant, than the solution of pure resveratrol or quercetin.     

A proposal for re-defining the way the aetiology of schizophrenia and bipolar human psychiatric diseases is investigated

“The two big problems — the nature of development and the nature of the mind — are being subdued. I don’t know whether there will be beautiful, general theories to come out of this — something really nice like Watson and Crick’s double helix — or whether there will be an accumulation of more and more details. I’ll confess to a secret hope for the former” (Crow 2000).     

The comparison of gastroprotective properties of Semax and its metabolites

Semax (MEHFPGP) was shown to increase gastric mucosal homeostasis to the action of such ulcerogenic factors as ethanol and stress. In the case of the stress model of ulcer formation, Semax and its two metabolites—HFPGP and FPGP—at the wide range of doses (0.06–3.7 μmol/kg) have demonstrated protective antiulcerogenic properties. In the case of ethanol model of ulcer formation, only Semax in two used doses (0.06 and 0.37 μmol/kg) reported reliable protective antiulcerogenic property. It was supposed that Semax’s gastroprotective activity directed to peripheral mechanisms of ulcerogenesis did not depend on its metabolites’ activities. On the contrary, Semax’s gastroprotective activity directed to the central mechanisms of ulcerogenesis might be also caused by gastroprotective activities of HFPGP and FPGP metabolites.     

Influence of Methionine and Vitamin E on Fluoride Concentration in Bones and Teeth of Rats Exposed to Sodium Fluoride in Drinking Water

Increased exposure to fluorine-containing compounds leads to accumulation of fluorides in hard tissues of bones and teeth, which may result in numerous skeletal and dental disorders. This study evaluates the influence of methionine and vitamin E on fluoride concentration in bones and teeth of rats subjected to long-term exposure to sodium fluoride in drinking water. The study was conducted in 30 3-month-old female Wistar FL rats. The animals were divided into five groups, six rats per group. The control group consisted of rats receiving only distilled water as drinking water. All other groups received NaF in the amount of 10 mg/kg of body mass/day in their drinking water. In addition, respective animal groups received: NaF + Met group—10 mg of methionine/kg of body mass/day, NaF + Met + E group—10 mg of methionine/kg of body mass/day and 3 mg of vitamin E (tocopheroli acetas)/rat/day and NaF + E group—3 mg of vitamin E/rat/day. Femoral bones and incisor teeth were collected for the study, and the fluoride concentration was determined using a fluoride ion-selective electrode. Fluoride concentration in both bones and teeth was found to be higher in the NaF and NaF + Met groups compared to the control group. In groups NaF + Met + E and NaF + E, the study material contained much lower fluoride concentration compared to the NaF group, while the effect was more prominent in the NaF + E group. The results of the studies indicate that methionine and vitamin E have opposite effects on accumulation of fluorides in hard tissue in rats. By stimulating fluoride accumulation, methionine reduces the adverse effect of fluorides on soft tissue, while vitamin E, which prevents excessive accumulation of fluorides in bones and teeth, protects these tissues from fluorosis. Therefore, it seems that combined application of both compounds would be optimal for the prevention of the adverse effects of chronic fluoride intoxication.     

Cellulolytic bacteria from soils in harsh environments

It is believed that the exposure of organisms to harsh climate conditions may select for differential enzymatic activities, making the surviving organisms a very promising source for bioprospecting. Soil bacteria play an important role in degradation of organic matter, which is mostly due to their ability to decompose cellulose-based materials. This work focuses on the isolation and identification of cellulolytic bacteria from soil found in two environments with stressful climate conditions (Antarctica and the Brazilian semi-arid caatinga). Cellulolytic bacteria were selected using enrichments at high and low temperatures (4 or 60°C) in liquid media (trypic soy broth—TSB and minimum salt medium—MM) supplemented with cellulose (1%). Many of the isolates (119 out of 254—46.9%) displayed the ability to degrade carboxymethyl-cellulose, indicating the presence of endoglucolytic activity, while only a minority of these isolates (23 out of 254—9.1%) showed exoglucolytic activity (degradation of avicel). The obtained isolates revealed a preferential endoglucolytic activity according to the temperature of enrichments. Also, the identification of some isolates by partial sequencing of the 16S rRNA gene indicated that the Bacteroidetes (e.g., Pedobacter, Chryseobacterium and Flavobacterium) were the main phylum of cellulolytic bacteria isolated from soil in Antarctica; the Firmicutes (e.g., Bacillus) were more commonly isolated from samples from the caatinga; and Actinobacteria were found in both types of soil (e.g., Microbacterium and Arthrobacter). In conclusion, this work reports the isolation of bacteria able to degrade cellulose-based material from soil at very low or very high temperatures, a finding that should be further explored in the search for cellulolytic enzymes to be used in the bioenergy industry.     

Conditions Under Which Nitrogen Can Limit Steady-State Net Primary Production in a General Class of Ecosystem Models

Human activity is drastically altering global nitrogen (N) availability. The extent to which ecosystems absorb additional N—and with it, additional CO₂—depends on whether net primary production (NPP) is N-limited, so it is important to understand conditions under which N can limit NPP. Here I use a general dynamical model to show that N limitation at steady-state—such as in old-growth forests—depends on the balance of biotically controllable versus uncontrollable N inputs and losses. Steady-state N limitation is only possible when uncontrollable inputs (for example, atmospheric deposition) exceed controllable losses (for example, leaching of plant-available soil N), which is the same as when uncontrollable losses (for example, leaching of plant-unavailable soil N) exceed controllable inputs (biological N fixation). These basic results are robust to many model details, such as the number of plant-unavailable soil N pools and the number and type of N fixers. Empirical data from old-growth tropical (Hawai’i) and temperate (Oregon, Washington, Chile) forests support the model insights. Practically, this means that any N fixer—symbiotic or not—could overcome ecosystem N limitation, so understanding N limitation requires understanding controls on all N fixers. Further, comparing losses of plant-available N to abiotic inputs could offer a rapid diagnosis of whether ecosystems can be N-limited, although the applicability of this result is constrained to ecosystems with a steady-state N cycle such as old-growth forests largely devoid of disturbance.     

Dynamics of small autocatalytic reaction networks—II. Replication,mutation and catalysis

Mutation is introduced into autocatalytic reaction networks. The differential equations obtained are neither of repliator-type nor can they be transformed straightway into a linear equation. Examples of low dimensional dynamical systems —n=2, 3 and 4 — are discussed and complete qualitative analysis is presented. Error thresholds known from simple replication-mutation kinetics with frequency independent replication rates occur here as well. Instead of cooperative transitions or higher order phase transitions the thresholds appear here as supercritical or subcritical bifurcations being analogous to first-order phase transitions.     

Correction factors used for estimating prey biomass in the diet of American minkMustela vison

Feeding experiment on nine feral minkMustela vison Schreber, 1777 was carried out to find differences in digestibility of particular prey types. The values of correction factors (CF), which show the ratio between consumed prey biomass and undigested remains, were calculated for seven food types. The experiment revealed that results obtained by commonly used percentage of occurrence methods differed from the real intake of food. Food types which were intensively digested were underestimated by percentage of occurrence methods and prey which had hardly digestive elements of their body were overestimated. The calculated values of CF are as follows: crayfish — 14.8, fish — 30.8, frog — 61.3, small passerine bird — 17.2, chicken — 41.3, rodent — 17.3, egg — 687.5. The variability in CF values did not depend on mink individuals but could be explained by the mean weight of prey items eaten by mink. The positive correlation between the prey size and its digestibility was recorded for crayfish, fish and chicken. The biomass of frog, passerine and rodent remains was not related to the body mass of eaten prey. The use of evaluated correction factors enables more accurate estimates of the food composition of wild living mustelids.     

Genetic analysis of short term callus culture and morphogenesis in pearl millet,Pennisetum glaucum

Genetic analysis of five in vitro characters was made through a 5 × 5 diallel analysis using callus derived from immature inflorescence segments of pearl millet (Pennisetum glaucum). The characters studied were: — volume of total callus, — frequency of embryogenic calli, — embryogenic callus volume, — growth rate in terms of increase in fresh weight, and — frequency of regeneration. High heritability values and heterosis were noticed for all these characters except for E callus frequency. Additive gene action was predominant for callus growth rate and frequency of regeneration. Of the five inbreds, IP 1346 (= P5) was found to be the best genetic background for embryogenic callus volume, embryogenic growth rate and frequency of regeneration. This revised version was published online in June 2006 with corrections to the Cover Date.     

Dental Mold: A Novel Formulation to Treat Common Dental Disorders

Oral administration of antibiotics to treat dental problems mostly yields slow actions due to slow onset and hepatic “first-pass.” Again, commonly used dental paints are generally washed out by saliva within few hours of application. To overcome the challenges, polymeric molds to be placed on an affected tooth (during carries and gum problems) were prepared and evaluated in vitro for sustained drug release for prolonged local action. Here, amoxicillin trihydrate and lidocaine hydrochloride were used as model drugs. Dental molds were prepared using corn zein, carbopol 934 P, gum karaya powder, and poloxamer 407 by mixing and solvent evaporation technique. Different physicochemical evaluation studies such as tooth adhesion test, surface pH, swelling index, and drug-distribution pattern were carried out. Percentage swelling varied from 56% to 93%. Average tooth adhesion strength and mean initial surface pH of the formulations were 50 g and 6.5, respectively. As assessed by scanning electron microscopy, drug distribution was uniform throughout the matrix. Cumulative percentage release of lidocaine hydrochloride and amoxicillin trihydrate in simulated saliva were 98% and 50%, respectively. In vitro drug-release studies revealed the sustained-release patterns of the drugs in simulated saliva at least for 24 h. The stability study shows that the drugs were stable in the formulations following the conditions as per ICH guideline. The formulation is a novel approach to deliver the drug(s) for a prolonged period for local action upon its application on an affected tooth.     

Some views on the role of noise in “self”-organizing systems

This paper deals with information transfer from the environment and “self”-organization in open, nonlinear systems far from thermodynamic equilibrium — in the presence of either non-stationary phase jitter noise, or amplitude stationary noise. By “self”-organization we mean here the progressive formation within the system of sequential, ordered (coherent) relationships between appropriate dynamical variables-like for example, the phase differences between the oscillating components of the system. We take up (in Section II) the classical Laser as a specific example and examine in detail the influence of phase jitter noise in the mode (phase) locking process. We find—as expected—that phase fluctuations in the cavity cause degradation of the coherent behaviour (i.e. increase the entropy) of the system — which, however, levels off, or saturates with time. Further (in Section III) we examine systems where the number of self-sustained oscillating components may vary with time in such a way that the maximum entropy of the system increases faster than the overall instantaneous entropy. We put forth the hypothesis that in such cases — because of the increase of the redundancy — the system gets organized not just in spite of, but merely because of the presence of Noise. Possible applications in biological systems (especially concerning a model of cerebral organization) are briefly discussed. It is understood here, that the system has to display some preliminary dynamical structure before the organizing procedure takes over. What happens afterwards is the subject of this paper.     

New RAPD markers of tomato spotted wilt virus (TSWV) resistance in Lycopersicon esculentum Mill

The selection of TSWV resistant individuals can be facilitated by molecular markers. RAPD analysis was carried out on three forms (Stevens × Rodade — resistant; Rey de los Tempranos — moderately tolerant; Potentat — susceptible) with the use of 271 primers. Out of 271 primers 28 generated stable polymorphism and so they were tested for linkage to resistance gene. Bulk segregant analysis (BSA) was applied to F₂ segregating progeny developed from resistant × susceptible parents. As a result, 5 primers enabling us to distinguish between resistant and susceptible forms were detected. Only one of them had previously been reported by Chague et al. (1996). The analysis should be repeated on a larger population to confirm the results obtained.     

Mourning and Forgiveness as Sites of Reconciliation Pedagogies

This paper explores mourning and forgiveness not simply as sources of existential, political, or emotional meaning, but primarily as possible sites of reconciliation pedagogies. Reconciliation pedagogies are public and school pedagogical practices that examine how certain ideas can enrich our thinking and action toward reconciliation—not through a moralistic agenda but through an approach that views such ideas both constructively and critically. Mourning and forgiveness may constitute valuable points of departure for reconciliation pedagogies, if common pain is acknowledged as an important aspect of rehumanizing the “enemy-other.” This work is difficult and the wider society may be skeptical; however, such work is about assisting a “never again” mentality develop in schools and civil society.     

The role of low molecular weight proteins in exposure of blood to laser radiation and varying magnetic field

In this work we studied variations of oxygen-binding capacity of hemoglobin under the separate and joint action of a nanointegrator—a special device that provides a low-intensity laser radiation (LILR, 655 nm)—and an alternating magnetic field (AMF) on blood (erythrocytes and plasma) in the presence of low molecular weight proteins (LWP). The action of LILR and AMF is demonstrated to increase oxygen absorption by 50% and, in the presence of LWP, by 80–100%. LILR reduces the activity of a blood enzyme superoxide dismutase (SOD) by 60% and, in the presence of LWP, by 40%. The joint action of LILR and AMF first stimulates and, after 30 min, inhibits SOD activity. It is shown that LILR and AMF action not only changes the anti-oxidant status of blood, but also promotes oxygen uptake by erythrocytes. The effect of radiation is enhanced due to nanomolecular changes in LWP structure that boost the absorption of oxygen by cells.     

Development and Evaluation of Buccal Bioadhesive Tablet of an Anti-emetic Agent Ondansetron

The aim of the present study was to develop and evaluate a buccal adhesive tablet containing ondansetron hydrochloride (OH). Special punches and dies were fabricated and used while preparing buccal adhesive tablets. The tablets were prepared using carbopol (CP 934), sodium alginate, sodium carboxymethylcellulose low viscosity (SCMC LV), and hydroxypropylmethylcellulose (HPMC 15cps) as mucoadhsive polymers to impart mucoadhesion and ethyl cellulose to act as an impermeable backing layer. The formulations were prepared by direct compression and characterized by different parameters such as weight uniformity, content uniformity, thickness, hardness, swelling index, in vitro drug release studies, mucoadhesive strength, and ex vivo permeation study. As compared with the optimized formulation composed of OH—5 mg, CP 934—30 mg, SCMC LV—165 mg, PEG 6000—40 mg, lactose—5 mg, magnesium stearate—1.5 mg, and aspartame—2 mg, which gave the maximum release (88.15%), non-bitter (OH) that form namely ondansetron base and complexed ondansetron was used in order to make the selected formulation acceptable to human. The result of the in vitro release studies and permeation studies through bovine buccal mucosa revealed that complexed ondansetron gave the maximum release and permeation. The stability of drug in the optimized adhesive tablet was tested for 6 h in natural human saliva; both the drug and device were found to be stable in natural human saliva. Thus, buccal adhesive tablet of ondansetron could be an alternative route to bypass the hepatic first-pass metabolism and to improve the bioavailability of (OH).