Prevention of biofilm formation by dairy products and N-acetylcysteine on voice prostheses in an artificial throat

OBJECTIVE

To evaluate the preventive effect of buttermilk, Yakult Light fermented milk drink and N-acetylcysteine on biofilm formation on voice prostheses in vitro.

MATERIAL AND METHODS

Groningen button and Provox 2 voice prostheses were inoculated with a mixture of bacteria and yeasts isolated from previously explanted Groningen button voice prostheses. After 5 h, separate throats were flushed with buttermilk, Yakult Light fermented milk drink, N-acetylcysteine or phosphate-buffered saline, which served as a control. After 7 days, the microflora on each voice prosthesis was determined.

RESULTS

On Groningen button voice prostheses, buttermilk, Yakult Light fermented milk drink and N-acetylcysteine all reduced the amount of both bacteria and yeasts. On Provox 2 voice prostheses, buttermilk, Yakult Light fermented milk drink and N-acetylcysteine reduced the amount of bacteria but, conversely, increased the amount of yeasts.

CONCLUSION

These in vitro experiments demonstrate that biofilm formation on voice prostheses is reduced in an artificial throat by the use of buttermilk, Yakult Light fermented milk drink and N-acetylcysteine. However, the structural differences between the type of voice prostheses may influence the ultimate effects.

Physicochemical properties and mechanism of drug release from ethyl cellulose matrix tablets prepared by direct compression and hot-melt extrusion

The objective of this research project was to determine the physicochemical properties and investigate the drug release mechanism from ethyl cellulose (EC) matrix tablets prepared by either direct compression or hot-melt extrusion (HME) of binary mixtures of water soluble drug (guaifenesin) and the polymer. Ethyl cellulose was separated into "fine" or "coarse" particle size fractions corresponding to 325-80 and 80-30 mesh particles, respectively. Tablets containing 30% guaifenesin were prepared at 10, 30, or 50 kN compaction forces and extruded at processing temperatures of 80-90 and 90-110 degrees C. The drug dissolution and release kinetics were determined and the tablet pore characteristics, tortuosity, thermal properties and surface morphologies were studied using helium pycnometry, mercury porosimetry, differential scanning calorimetry and scanning electron microscopy. The tortuosity was measured directly by a novel technique that allows for the calculation of diffusion coefficients in three experiments. The Higuchi diffusion model, Percolation Theory and Polymer Free Volume Theory were applied to the dissolution data to explain the release properties of drug from the matrix systems. The release rate was shown to be dependent on the ethyl cellulose particle size, compaction force and extrusion temperature.

[Development of throat clearing herbal teas]

Medicinal herbs in tea for throat clearing are used from ancient times. Taking into consideration the bronchial mucus secretion stimulating and antispasmodic, antimicrobial, antiphlogistic and stimulating effect on the ciliated epithelium two new formulations of throat clearing herbal tea were originated. The first formulation consists of liquorice roots, sweet fennel and thyme, and the second one consists of pine gemmae, thyme and elder flowers. The methods for identification and assay of the active substances of the components were adapted. The purity of the mixtures was regulated by the limitation of the loss on drying, total ash, microbial contamination, contamination with radionuclides, heavy metals, pesticides and foreign matter. Expiry date of both throat clearing herbal teas was confirmed to be 2 years.

[Effects of fudosteine, a new cysteine derivative, on airway secretion in rabbits and rats]

We examined the effects of fudosteine [(-)-(R)-2-amino-3-(3-hydroxypropylthio) propionic acid], a new cysteine derivative, on airway secretion in rabbits and rats. Indirect measurement of airway secretion in rabbits, which was expressed by the amount of dye excreted into the respiratory tract, was carried out according to the Sakuno's method, with some modifications. Fudosteine (500 mg/kg, p.o.) significantly increased the amount of dye excreted into the respiratory tract. As a direct method of measurement of airway secretion, the modified Perry and Boyd's method was used to collect respiratory tract fluid (RTF) in rabbits. Fudosteine (500 mg/kg, p.o.) significantly augmented the output volume of RTF, but there was no difference from the control in protein and phosphatidylcholine (PC) contents into RTF. On the other hand, fudosteine increased chloride ion concentration in broncho-alveolar lavage of rats. Fudosteine did not stimulate PC secretion in a primary culture of rat type II pneumocytes, and it did not have a mucolytic effect against gastric mucin in vitro. From the results described above, it was concluded that fudosteine may be a new cysteine derivative which offers a serous secretion.

Studies in enzyme cytochemistry I. Principles of cytochemical staining methods

Advances that could accrue from the introduction of photometric methods into cytochemical staining practice include the investigation, by cytophotometry, of the mechanism of enzyme action in situ and the possible identification of closely similar enzymes by the direct determination of their Michaelis-Menten constants in the cell or tissue. After brief mention of the fundamental limitations of stain cytochemistry associated with (i) enzyme specificity, and (ii) the need for preliminary treatment such as fixation, a study is made of the theoretical basis of those staining methods which can be classified under the scheme substrate enzymic → reaction stain precursor 'capture reaction' → with developing agent stain. These are considered in relation to a radially symmetrical model in which the enzyme is taken to be uniformly distributed in a spherical site, selected as the simplest that approximates to many actual sites. The overall process is simplified, without undue error, by division into stages. A brief survey of substrate penetration is followed by detailed study of the production, diffusion, and chemical removal of the stain precursor. Little is known about the mechanism of stain immobilization, but on the assumption of non-diffusibility, the stain density patterns are given for various values of the (first order) velocity constant of the capture reaction, diffusion coefficient of the stain precursor, and enzyme-site radius. A localization factor (degree of localization, F ) is defined, which gives an indication of the intrinsic localization possibilities of any cytochemical method. This has value in both theoretical and experimental study. Values for F have been calculated, corresponding to the kinetic and geometrical parameters mentioned above. In order to satisfy the objective requirements that emerge from the theory, certain generalizations may be made concerning the properties of prospective substrates. The substrate itself should not associate with protein, except possibly the specific enzyme species, but it should yield a stain precursor and a stain, both of which should associate strongly with protein, i. e. be highly substantive molecules. Unless precursor-protein association occurs, extremely high capture reaction velocities are necessary for precise enzyme mapping in small sites.

Novel therapy for COPD

The incidence of chronic obstructive pulmonary disease (COPD) is increasing throughout the world. Much less is known about the pathogenesis of COPD than that of asthma and there is little response to current therapy. Most patients with COPD have acquired their lung disease through smoking cigarettes, and the major step in management is to minimise further damage by stopping this habit. A number of therapies are being developed for the treatment of COPD; including new bronchodilators such as tiotropium bromide, agents to block inflammation induced by neutrophils and macrophages, as well as strategies to combat proteases and oxidants. The long-term goal is to provide therapy that retards the accelerated loss of lung function occurring in COPD. Development of novel therapies for COPD requires reliable Phase II decision making before entering large scale Phase III studies. The patient with COPD is often overlooked compared to their asthmatic counterpart, who benefit from an urgent need to identify novel targets and better therapy.

III. Relationships between solubility, molecular association and structure in indigoid dyes

The bearing of lipid solubilities and substantivities of dyes on the results of cytochemical staining reactions is briefly discussed. Solubilities of indigoid dyes in various lipids are qualitatively similar to those in sym tetrachloroethane. Quantitative determinations made in this solvent indicate that, in general, indigo and its 5:5΄- and 6:6΄-substituted derivatives are sparingly soluble, whereas the corresponding 4:4΄- and 7:7΄-substituted dyes are relatively very soluble. The enhanced solubilities of the latter dyes are consistent with the hypothesis that the substituents interfere with edge-to-edge hydrogen-bonded association otherwise present in indigo and its 5:5΄- and 6:6΄-substituted derivatives. This hypothesis is supported by mutually consistent results given by solubility, melting point and infra-red spectrographic studies. Indigoid dyes possessing small substituents in the 4:4΄-position, such as 4:4΄-dichloro-indigo, are highly substantive and therefore potentially of great value when formed in cytochemical staining reactions.

[Effects of ambroxol HCl on the guinea pig tracheal mucous secretion and the rat pulmonary surfactant secretion]

The effects of orally administered ambroxol HCl (ambroxol) on guinea pig tracheal mucous secretion and rat pulmonary surfactant secretion were investigated histologically and biochemically. Ambroxol significantly increased the number of active goblet cells in guinea pig tracheal epithelium and total mucopolysaccharide level. Moreover, ambroxol significantly increased the neutral mucopolysaccharide level and PAS-positive substance in the guinea pig tracheal submucosal glands. Ambroxol did not show a significant effect on the content of the total phosphatidylcholine in rat lung lavage fluid, while ambroxol significantly increased the ratio of disaturated phosphatidylcholine to total phosphatidylcholine. From these results, it is suggested that ambroxol increases both the tracheal mucous secretion, especially the neutral mucopolysaccharide, and pulmonary surfactant secretion and these effects reflect part of the expectorant mechanism of the drug.