Synchronous fluorescence and UV–vis spectroscopic studies of interactions between the tetracycline antibiotic, aluminium ions and DNA with the aid of the Methylene Blue dye probe

Synchronous fluorescence spectroscopy (SFS) was applied for the investigation of interactions of the antibiotic, tetracycline (TC), with DNA in the presence of aluminium ions (Al3+). The study was facilitated by the use of the Methylene Blue (MB) dye probe, and the interpretation of the spectral data with the aid of the chemometrics method, parallel factor analysis (PARAFAC). Three-way synchronous fluorescence analysis extracted the important optimum constant wavelength differences, Δλ, and showed that for the TC–Al3+–DNA, TC–Al3+ and MB dye systems, the associated Δλ values were different (Δλ = 80, 75 and 30 nm, respectively). Subsequent PARAFAC analysis demonstrated the extraction of the equilibrium concentration profiles for the TC–Al3+, TC–Al3+–DNA and MB probe systems. This information is unobtainable by conventional means of data interpretation. The results indicated that the MB dye interacted with the TC–Al3+–DNA surface complex, presumably via a reaction intermediate, TC–Al3+–DNA–MB, leading to the displacement of the TC–Al3+ by the incoming MB dye probe.

The relationship between otolith increments and time for yellowfin and skipjack tuna marked with tetracycline

ENGLISH: The rate at which increments are deposited on the sagittal otoliths of yellowfin (Thunnus albacares) and skipjack (Katsuwonus p elamis) tunas is determined by a markrecapture experiment using tetracycline. During growth in fork length from 40 to 110 em, and for a period of up to 389 days, yellowfin of the Revillagigedo Islands- Baja California region deposit one increment per day in either the postrostrum or rostrum position of the otolith. For skipjack of the same region, rostrum increments underestimate time by approximately 24 percent during growth from 42 to 64 cm and over the maximum interval of 249 days. The growth rate of each species is estimated from the recapture fork length and the linear change in an otolith dimension following tetracycline injection. Over specific ranges in fork length the rates are 3.06 and 1.15 em per month for yellowfin and skipjack, respectively. SPANISH: La rapidez (tasa) en la que se depositan los incrementos en los otolitos sagitales del aleta amarilla (Thunnus albacares) y el barrilete (Katsuwonus pelamis) se determina mediante un experimento al recapturar los peces que han sido marcados con tetraciclina. Durante el crecimiento de la longitud de horquilla de 40 a 110 cm y por un período hasta de 389 días, se forma en el aleta amarilla de la región de las Islas Revillagigedo-Baja California, un incremento diario ya sea en el parte del postrostrum o rostrum de los otolitos. Con respecto al barrilete de la misma region los incrementos en el rostrum subestiman aproximadamente el tiempo en un 24 por ciento durante el crecimiento de 42 a 64 cm y sobre un intervalo máximo de 249 días. El índice de crecimiento de cada especie se estima en la recaptura según la longitud de horquilla y el cambio lineal en la dimensión de un otolito después de la inyección de tetraciclina. La variación específica sobre la longitud de horquilla de los índices son 3.06 y 1.15 cm por mes para el aleta amarilla y el barrilete, respectivamente. (PDF contains 54 pages.)

Validation of back-calculation equations for juvenile bluefish (Pomatomus saltatrix) with the use of tetracycline-marked otoliths

In recent years, a decrease in the abundance of bluefish (Pomatomus saltatrix) has been observed (Fahay et al., 1999; Munch and Conover, 2000) that has led to increased interest in a better understanding the life history of the species. Estimates of several young-of-the-year (YOY) life history characteristics, including the importance and use of estuaries as nursery habitat (Kendall and Walford, 1979) and size-dependant mortality (Hare and Cowen, 1997), are reliant upon the accuracy of growth determination. By using otoliths, it is possible to use back-calculation formulae (BCFs) to estimate the length at certain ages and stages of development for many species of fishes. Use of otoliths to estimate growth in this way can provide the same information as long-term laboratory experiments and tagging studies without the time and expense of rearing or recapturing fish. The difficulty in using otoliths in this way lies in validating that 1) there is constancy in the periodicity of the increment formation, and 2) there is no uncoupling of the relationship between somatic and otolith growth. To date there are no validation studies demonstrating the relationship between otolith growth and somatic growth for bluefish. Daily increment formation in otoliths has been documented for larval (Hare and Cowen, 1994) and juvenile bluefish (Nyman and Conover, 1988). Hare and Cowen (1995) found ageindependent variability in the ratio of otolith size to body length in early age bluefish, although these differences varied between ontogenetic stages. Furthermore, there have been no studies where an evaluation of back-calculation methods has been combined with a validation of otolithderived lengths for juvenile bluefish.

Diverse tetracycline resistant bacteria and resistance genes from coastal waters of Jiaozhou Bay

Environmental microbiology investigation was carried out in Jiaozhou Bay to determine the source and distribution of tetracycline-resistant bacteria and their resistance mechanisms. At least 25 species or the equivalent molecular phylogenetic taxa in 16 genera of resistant bacteria could be identified based on 16S ribosomal deoxyribonucleic acid sequence analysis. Enterobacteriaceae, Pseudomonadaceae, and Vibrionaceae constituted the majority of the typical resistant isolates. Indigenous estuarine and marine Halomonadaceae, Pseudoalteromonadaceae, Rhodobacteraceae, and Shewanellaceae bacteria also harbored tetracycline resistance. All the six resistance determinants screened, tet(A)-(E) and tet(G), could be detected, and the predominant genes were tet(A), tet(B), and tet(G). Both anthropogenic activity-related and indigenous estuarine or coastal bacteria might contribute to the tet gene reservoir, and resistant bacteria and their molecular determinants may serve as bioindicators of coastal environmental quality. Our work probably is the first identification of tet(E) in Proteus, tet(G) in Acinetobacter, tet(C) and tet(D) in Halomonas, tet(D) and tet(G) in Shewanella, and tet(B), tet(C), tet(E), and tet(G) in Roseobacter.

Formulation and characterisation of tetracycline-containing bioadhesive polymer networks designed for the treatment of periodontal disease.

This study described the drug release, rheological (dynamic and flow) and textural/mechanical properties of a series of formulations composed of 15% w/w polymethylvinylether-co-maleic anhydride (PMVE-MA), 0-9% w/w polyvinylpyrrolidone (PVP) and containing 1-5% w/w tetracycline hydrochloride, designed for the treatment of periodontal disease. All formulations exhibited pseudoplastic flow with minimal thixotropy. Increasing the concentration of PVP sequentially increased the zero-rate viscosity (derived from the Cross model) and the hardness and compressibility of the formulations (derived from texture profile analysis). These affects may be accredited to increased polymer entanglement and, in light of the observed synergy between the two polymers with respect to their textural and rheological properties, interaction between PVP and PMVE-MA. Increasing the concentration of PVP increased the storage and loss moduli yet decreased the loss tangent of all formulations, indicative of increased elastic behaviour. Synergy between the two polymers with respect to their viscoelastic properties was observed. Increased adhesiveness, associated with increased concentrations of PVP was ascribed to the increasing bioadhesion and tack of the formulations. The effect of increasing drug concentration on the rheological and textural properties was dependent on PVP concentration. At lower concentrations (0, 3% w/w) no effect was observed whereas, in the presence of 9% w/w PVP, increasing drug concentration increased formulation elasticity, zero rate viscosity, hardness and compressibility. These observations were ascribed to the greater mass of suspended drug in formulations containing the highest concentration of PVP. Drug release from formulations containing 6 and 9% PVP (and 5% w/w drug) was prolonged and swelling/diffusion controlled. Based on the drug release, rheological and textural properties, it is suggested that the formulation containing 15% w/w PMVE-MA, 6% w/w PVP and tetracycline hydrochloride (5% w/w) may be useful for the treatment of periodontal disease.

Design, characterisation and preliminary clinical evaluation of a novel mucoadhesive topical formulation containing tetracycline for the treatment of periodontal disease

This study describes the formulation, characterisation and preliminary clinical evaluation of mucoadhesive, semi-solid formulations containing hydroxyethylcellulose (HEC, 1-5%, w/w), polyvinylpyrrolidine (PVP, 2 or 3%, w/w), poly carbophil (PC, 1 or 3%, w/w) and tetracycline (5%, w/w, as the hydrochloride). Each formulation was characterised in terms of drug release, hardness, compressibility, adhesiveness (using a texture analyser in texture profile analysis mode), syringeability (using a texture analyser in compression mode) and adhesion to a mucin disc (measured as a detachment force using the texture analyser in tensile mode). The release exponent for the formulations ranged from 0.78+/-0.02 to 1.27+/-0.07, indicating that drug release was non-diffusion controlled. Increasing the concentrations of each polymeric component significantly increased the time required for 10 and 30% release of the original mass of tetracycline, due to both increased viscosity and, additionally, the unique swelling properties of the formulations. Increasing concentrations of each polymeric component also increased the hardness, compressibility, adhesiveness, syringeability and mucoadhesion of the formulations. The effects on product hardness, compressibility and syringeability may be due to increased product viscosity and, hence, increased resistance to compression. Similarly, the effects of these polymers on adhesiveness/mucoadhesion highlight their mucoadhesive nature and, importantly, the effects of polymer state (particularly PC) on these properties. Thus, in formulations where the neutralisation of PC was maximally suppressed, adhesiveness and mucoadhesion were also maximal. Interestingly, statistical interactions were primarily observed between the effects of HEC and PC on drug release, mechanical and mucoadhesive properties. These were explained by the effects of HEC on the physical state of PC, namely swollen or unswollen. In the preliminary clinical evaluation, a formulation was selected that offered an appropriate balance of the above physical properties and contained 3% HEC, 3% PVP and 1% PC, in addition to tetracycline 5% (as the hydrochloride). The clinical efficacy of this (test) formulation was compared to an identical tetracycline-devoid (control) formulation in nine periodontal pockets (greater than or equal to 5 mm depth). One week following administration of the test formulation, there was a significant improvement in periodontal health as identified by reduced numbers of sub-gingival microbial pathogens. Therefore, it can be concluded that, when used in combination with mechanical plaque removal, the tetracycline-containing semi-solid systems described in this study would augment such therapy by enhancing the removal of pathogens, thus improving periodontal health. (C) 2000 Elsevier Science B.V. All rights reserved.

Development and mechanical characterization of bioadhesive semi-solid, polymeric systems containing tetracycline for the treatment of periodontal diseases

Purpose. This study examined the mechanical characteristics and release of tetracycline from bioadhesive, semi-solid systems which were designed for the treatment of periodontal diseases.

In vitro studies on colonization resistance of the human gut microbiota to Candida albicans and the effects of tetracycline and Lactobacillus plantarum LPK

An anaerobic three-vessel continuous-flow culture system, which models the three major anatomical regions of the human colon, was used to study the persistence of Candida albicans in the presence of a faecal microbiota. During steady state conditions, overgrowth of C. albicans was prevented by commensal bacteria indigenous to the system. However antibiotics, such as tetracycline have the ability to disrupt the bacterial populations within the gut. Thus, colonization resistance can be compromised and overgrowth of undesirable microorganisms like C. albicans can then occur. In this study, growth of C. albicans was not observed in the presence of an established faecal microbiota. However, following the addition of tetracycline to the growth medium, significant growth of C. albicans occurred. A probiotic Lactobacillus plantarum LPK culture was added to the system to investigate whether this organism had any effects upon the Candida populations. Although C. albicans was not completely eradicated in the presence of this bacterium, cell counts were markedly reduced, indicating a compromised physiological function. This study shows that the normal gut flora can exert 'natural' resistance to C. albicans, however this may be diminished during antibiotic intake. The use of probiotics can help fortify natural resistance.